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1

Fatigue reliability of wind turbine components  

NASA Astrophysics Data System (ADS)

Fatigue life estimates for wind turbine components can be extremely variable due to both inherently random and uncertain parameters. A structural reliability analysis is used to qualify the probability that the fatigue life will fall short of a selected target. Reliability analysis also produces measures of the relative importance of the various sources of uncertainty and the sensitivity of the reliability to each input parameter. The process of obtaining reliability estimates is briefly outlined. An example fatigue reliability calculation for a blade joint is formulated; reliability estimates, importance factors, and sensitivities are produced. Guidance in selecting distribution functions for the random variables used to model the random and uncertain parameters is also provided.

Veers, P. S.

2

225-kW Dynamometer for Testing Small Wind Turbine Components: Preprint  

SciTech Connect

This paper describes NREL's new 225-kW dynamometer facility that is suitable for testing a variety of components and subsystems for small wind turbines and discusses opportunities for industry partnerships with NREL for use of the facility.

Green, J.

2006-06-01

3

Wind turbine  

DOEpatents

A wind turbine of the type having an airfoil blade (15) mounted on a flexible beam (20) and a pitch governor (55) which selectively, torsionally twists the flexible beam in response to wind turbine speed thereby setting blade pitch, is provided with a limiter (85) which restricts unwanted pitch change at operating speeds due to torsional creep of the flexible beam. The limiter allows twisting of the beam by the governor under excessive wind velocity conditions to orient the blades in stall pitch positions, thereby preventing overspeed operation of the turbine. In the preferred embodiment, the pitch governor comprises a pendulum (65,70) which responds to changing rotor speed by pivotal movement, the limiter comprising a resilient member (90) which engages an end of the pendulum to restrict further movement thereof, and in turn restrict beam creep and unwanted blade pitch misadjustment.

Cheney, Jr., Marvin C. (Glastonbury, CT)

1982-01-01

4

Wind Turbine Bearing Failure Detection Using Generator Stator Current Homopolar Component  

E-print Network

Wind Turbine Bearing Failure Detection Using Generator Stator Current Homopolar Component Ensemble detection of the generator health degeneration, facilitating a proactive response, minimizing downtime on the homopolar component of the generator stator current and attempts to highlight the use of the Ensemble

Paris-Sud XI, Université de

5

Investigation of Data Fusion Applied to Health Monitoring of Wind Turbine Drive train Components  

NASA Technical Reports Server (NTRS)

The research described was performed on diagnostic tools used to detect damage to dynamic mechanical components in a wind turbine gearbox. Different monitoring technologies were evaluated by collecting vibration and oil debris data from tests performed on a "healthy" gearbox and a damaged gearbox in a dynamometer test stand located at the National Renewable Energy Laboratory. The damaged gearbox tested was removed from the field after experiencing component damage due to two losses of oil events and was retested under controlled conditions in the dynamometer test stand. Preliminary results indicate oil debris and vibration can be integrated to assess the health of the wind turbine gearbox.

Dempsey, Paula J.; Sheng, Shuangwen

2011-01-01

6

Wind turbine acoustics  

NASA Technical Reports Server (NTRS)

Available information on the physical characteristics of the noise generated by wind turbines is summarized, with example sound pressure time histories, narrow- and broadband frequency spectra, and noise radiation patterns. Reviewed are noise measurement standards, analysis technology, and a method of characterizing wind turbine noise. Prediction methods are given for both low-frequency rotational harmonics and broadband noise components. Also included are atmospheric propagation data showing the effects of distance and refraction by wind shear. Human perception thresholds, based on laboratory and field tests, are given. Building vibration analysis methods are summarized. The bibliography of this report lists technical publications on all aspects of wind turbine acoustics.

Hubbard, Harvey H.; Shepherd, Kevin P.

1990-01-01

7

Metallic wear debris sensors: promising developments in failure prevention for wind turbine gearsets and similar components  

NASA Astrophysics Data System (ADS)

Wind turbines are frequently located in remote, hard-to-reach locations, making it difficult to apply traditional oil analysis sampling of the machine's critical gearset at timely intervals. Metal detection sensors are excellent candidates for sensors designed to monitor machine condition in vivo. Remotely sited components, such as wind turbines, therefore, can be comfortably monitored from a distance. Online sensor technology has come of age with products now capable of identifying onset of wear in time to avoid or mitigate failure. Online oil analysis is now viable, and can be integrated with onsite testing to vet sensor alarms, as well as traditional oil analysis, as furnished by offsite laboratories. Controlled laboratory research data were gathered from tests conducted on a typical wind turbine gearbox, wherein total ferrous particle measurement and metallic particle counting were employed and monitored. The results were then compared with a physical inspection for wear experienced by the gearset. The efficacy of results discussed herein strongly suggests the viability of metallic wear debris sensors in today's wind turbine gearsets, as correlation between sensor data and machine trauma were very good. By extension, similar components and settings would also seem amenable to wear particle sensor monitoring. To our knowledge no experiments such as described herein, have previously been conducted and published.

Poley, Jack; Dines, Michael

2011-04-01

8

Damage predictions for wind turbine components using the LIFE2 computer code  

NASA Astrophysics Data System (ADS)

The LIFE2 computer code is a fatigue/fracture analysis code that is specialized to the analysis of wind turbine components. It is a PC-compatible FORTRAN code that is written in a top-down modular format. The service lifetime of a component can be divided into three phases: crack initiation, growth and coalescence of micro-cracks and growth of a macro-crack. In the LIFE2 formulation, a S-n fatigue analysis is used to describe the first two phases and a linear, da/dn fracture analysis is used to describe the third phase. The code is divided into five main sections. The first four describe the wind resource, the constitutive properties of the turbine material, the stress state in which the turbine operates and operational parameters for the turbine system. The fifth uses the data files written by the first four sections to calculate the service lifetime of a turbine component. In addition to the main sections, auxiliary sections are included to permit the storage of data and code calculations and to permit the plotting of results. This report describes the computational framework used in the LIFE2 code to evaluate the damage rules cited above. An example problem is presented here to illustrate the capabilities of the code.

Sutherland, Herbert J.

9

Turbulence descriptors for scaling fatigue loading spectra of wind turbine structural components  

SciTech Connect

The challenge for the designer in developing a new wind turbine is to incorporate sufficient strength in its components to safely achieve a 20- or 30-year service life. To accomplish this, the designer must understand the load and stress distributions (in a statistical sense at least) that the turbine is likely to encounter during its operating life. Sources of loads found in the normal operating environment include start/stop cycles, emergency shutdowns, the turbulence environment associated with the specific site and turbine location, and extreme or ``rare`` events that can challenge the turbine short-term survivability. Extreme events can result from an operational problem (e.g., controller failure) or violent atmospheric phenomena (tornadic circulations, strong gust fronts). For the majority of the operating time, however, the character of the turbulent inflow is the dominant source of the alternating stress distributions experienced by the structural components. Methods of characterizing or scaling the severity of the loading spectra (or the rate of fatigue damage accumulation) must be applicable to a wide range of turbulent inflow environments -- from solitary isolation to the complex flows associated with multi-row wind farms. The metrics chosen must be related to the properties of the turbulent inflow and independent of the nature of local terrain features.

Kelley, N.D.

1994-07-01

10

Floating wind turbine system  

NASA Technical Reports Server (NTRS)

A floating wind turbine system with a tower structure that includes at least one stability arm extending therefrom and that is anchored to the sea floor with a rotatable position retention device that facilitates deep water installations. Variable buoyancy for the wind turbine system is provided by buoyancy chambers that are integral to the tower itself as well as the stability arm. Pumps are included for adjusting the buoyancy as an aid in system transport, installation, repair and removal. The wind turbine rotor is located downwind of the tower structure to allow the wind turbine to follow the wind direction without an active yaw drive system. The support tower and stability arm structure is designed to balance tension in the tether with buoyancy, gravity and wind forces in such a way that the top of the support tower leans downwind, providing a large clearance between the support tower and the rotor blade tips. This large clearance facilitates the use of articulated rotor hubs to reduced damaging structural dynamic loads. Major components of the turbine can be assembled at the shore and transported to an offshore installation site.

Viterna, Larry A. (Inventor)

2009-01-01

11

Wind tower turbine  

Microsoft Academic Search

A wind powered turbine drive for an electric generator is disclosed in which both the generator and the turbine driving it are stationary and remain in a fixed position irrespective of wind direction. This turbine facilitates electric power generation by wind power in those higher power ranges where the greater generator and turbine weights otherwise make it difficult and costly

OHare

1981-01-01

12

EEMD-based wind turbine bearing failure detection using the generator stator current homopolar component  

NASA Astrophysics Data System (ADS)

Failure detection has always been a demanding task in the electrical machines community; it has become more challenging in wind energy conversion systems because sustainability and viability of wind farms are highly dependent on the reduction of the operational and maintenance costs. Indeed the most efficient way of reducing these costs would be to continuously monitor the condition of these systems. This allows for early detection of the generator health degeneration, facilitating a proactive response, minimizing downtime, and maximizing productivity. This paper provides then an assessment of a failure detection techniques based on the homopolar component of the generator stator current and attempts to highlight the use of the ensemble empirical mode decomposition as a tool for failure detection in wind turbine generators for stationary and non-stationary cases.

Amirat, Yassine; Choqueuse, Vincent; Benbouzid, Mohamed

2013-12-01

13

The LIFE computer code: Fatigue life prediction for vertical axis wind turbine components  

NASA Astrophysics Data System (ADS)

The LIFE computer code was originally written by Veers to analyze the fatigue life of a vertical axis wind turbine (VAWT) blade. The basic assumptions built into this analysis tool are: the fatigue life of a blade component is independent of the mean stress; the frequency distribution of the vibratory stresses may be described adequately by a Rayleigh probability density function; and damage accumulates linearly (Miner's Rule). Further, the yearly distribution of wind is assumed to follow a Rayleigh distribution. The original program has been updated to run in an interactive mode on a personal computer with a BASIC interpreter and 256K RAM. Additional capabilities included in this update include: the generalization of the Rayleigh function for the wind speed distribution to a Weibull function; the addition of two constitutive rules for the evaluation of the effects of mean stress on fatigue life; interactive data input; and the inclusion of a stress concentration factor into the analysis.

Sutherland, H. J.; Ashwill, T. D.; Slack, N.

1987-08-01

14

Airship-floated wind turbine  

SciTech Connect

A wind turbine, by use of a tethered airship for support, may be designed for the economical recovery of power at heights of 2,000 feet or more above ground, at which height power density in the wind is typically three times the power density available to a conventionally supported wind turbine. Means can be added to such an airship-floated wind turbine which will permit its generators to be used to meet load demand even during periods of little or no wind. Described to this end is a wind turbine system which combines, among other novel features: a novel tether line system which provides access for men and materials to the supporting airship while in active service, a novel system for providing additional buoyant lift at the nose of the turbine-supporting airship to offset the vertical component of tension induced in the tether line by the downwind force exerted by the turbine blades, a novel bearing assembly at the nose of the supporting airship which permits the airship to rotate as a unit with the turbine it supports without causing a similar rotation of the tether line, a novel turbine airship structure which handles concentrated loads from the turbine efficiently and also permits the safe use of hydrogen for buoyancy, a novel ''space frame'' structure which supports the turbine blades and greatly reduces blade weight, a novel system for controlling turbine blade angle of incidence and for varying blade incidene in synchrony with blade angular position abut the turbine axis to provide greater control over airship movement, a novel system for locating propellor-driven generators out at the wind turbine perimeter and for using lightweight, high-RPM generators to produce electrical energy at a power line frequency, which greatly reduces the weight required to convert turbine blade torque into useful power, and a novel system for incorporating compressed air storage and combustion turbine components into the wind turbine's generator drive systems.

Watson, W. K.

1985-01-01

15

Large wind turbine generators  

NASA Technical Reports Server (NTRS)

The development associated with large wind turbine systems is briefly described. The scope of this activity includes the development of several large wind turbines ranging in size from 100 kW to several megawatt levels. A description of the wind turbine systems, their programmatic status and a summary of their potential costs is included.

Thomas, R. L.; Donovon, R. M.

1978-01-01

16

Energy 101: Wind Turbines - 2014 Update  

ScienceCinema

See how wind turbines generate clean electricity from the power of wind. The video highlights the basic principles at work in wind turbines, and illustrates how the various components work to capture and convert wind energy to electricity. This updated version also includes information on the Energy Department's efforts to advance offshore wind power. Offshore wind energy footage courtesy of Vestas.

None

2014-06-05

17

Energy 101: Wind Turbines - 2014 Update  

SciTech Connect

See how wind turbines generate clean electricity from the power of wind. The video highlights the basic principles at work in wind turbines, and illustrates how the various components work to capture and convert wind energy to electricity. This updated version also includes information on the Energy Department's efforts to advance offshore wind power. Offshore wind energy footage courtesy of Vestas.

None

2014-05-06

18

Statistical and time domain signal analysis of the thermal behaviour of wind turbine drive train components under dynamic operation conditions  

NASA Astrophysics Data System (ADS)

Gearboxes and generators are fundamental components of all electrical machines and the backbone of all electricity generation. Since the wind energy represents one of the key energy sources of the future, the number of wind turbines installed worldwide is rapidly increasing. Unlike in the past wind turbines are more often positioned in arctic as well as in desert like regions, and thereby exposed to harsh environmental conditions. Especially the temperature in those regions is a key factor that defines the design and choice of components and materials of the drive train. To optimize the design and health monitoring under varying temperatures it is important to understand the thermal behaviour dependent on environmental and machine parameters. This paper investigates the behaviour of the stator temperature of the double fed induction generator of a wind turbine. Therefore, different scenarios such as start of the turbine after a long period of no load, stop of the turbine after a long period of full load and others are isolated and analysed. For each scenario the dependences of the temperature on multiple wind turbine parameters such as power, speed and torque are studied. With the help of the regression analysis for multiple variables, it is pointed out which parameters have high impact on the thermal behaviour. Furthermore, an analysis was done to study the dependences in the time domain. The research conducted is based on 10 months of data of a 2 MW wind turbine using an adapted data acquisition system for high sampled data. The results appear promising, and lead to a better understanding of the thermal behaviour of a wind turbine drive train. Furthermore, the results represent the base of future research of drive trains under harsh environmental conditions, and it can be used to improve the fault diagnosis and design of electrical machines.

Nienhaus, K.; Hilbert, M.; Baltes, R.; Bernet, C.

2012-05-01

19

User's manual for FAROW: Fatigue and reliability of wind turbine components, version 1.1  

NASA Astrophysics Data System (ADS)

FAROW is a Computer program that assists in the probabilistic analysis of the Fatigue and Reliability of wind turbines. The fatigue lifetime of wind turbine components is calculated using functional forms for important input quantities. Parameters of these functions are defined in an input file as either constants or random variables. The user can select from a library of random variable distribution functions. FAROW uses structural reliability techniques to calculate the mean time to failure, probability of failure before a target lifetime, relative importance of each of the random inputs, and the sensitivity of the reliability to all input parameters. Monte Carlo simulation is also available. This user's manual is intended to provide sufficient information to knowledgeably run the program and meaningfully interpret the results. The first chapter provides an overview of the approach and the results. Chapter 2 describes the formulation and assumptions used in the fatigue life calculations. Each of the input parameters is described in detail in Chapter 3 along with hints and warnings on usage. An explanation of the outputs is provided in Chapter 4. Two example problems are described and solved in Chapter 5, one for the case where extensive data are available and the other with limited data where the uncertainty is higher. A typical input file and the output files for the example problems are included in the appendices.

Veers, Paul S.; Winterstein, Steven R.; Lange, Clifford H.; Wilson, Tracy A.

1994-11-01

20

Wind Turbine Structural Dynamics  

NASA Technical Reports Server (NTRS)

A workshop on wind turbine structural dynamics was held to review and document current United States work on the dynamic behavior of large wind turbines, primarily of the horizontal-axis type, and to identify and discuss other wind turbine configurations that may have lower cost and weight. Information was exchanged on the following topics: (1) Methods for calculating dynamic loads; (2) Aeroelasticity stability (3) Wind loads, both steady and transient; (4) Critical design conditions; (5) Drive train dynamics; and (6) Behavior of operating wind turbines.

Miller, D. R. (editor)

1978-01-01

21

Wind Turbines Benefit Crops  

ScienceCinema

Ames Laboratory associate scientist Gene Takle talks about research into the effect of wind turbines on nearby crops. Preliminary results show the turbines may have a positive effect by cooling and drying the crops and assisting with carbon dioxide uptake.

Takle, Gene

2013-03-01

22

Wind Turbines Benefit Crops  

SciTech Connect

Ames Laboratory associate scientist Gene Takle talks about research into the effect of wind turbines on nearby crops. Preliminary results show the turbines may have a positive effect by cooling and drying the crops and assisting with carbon dioxide uptake.

Takle, Gene

2010-01-01

23

Advanced wind turbine design  

Microsoft Academic Search

Garrad Hassan have a project in progress funded by the U.K. Department of Trade and Industry (DTI) to assess the prospects and cost benefits of advanced wind turbine design. In the course of this work, a new concept, the coned rotor design, has been developed. This enables a wind turbine system to operate in effect with variable rotor diameter augmenting

P. M. Jamieson; A. Jaffrey

1997-01-01

24

On the Fatigue Analysis of Wind Turbines  

SciTech Connect

Modern wind turbines are fatigue critical machines that are typically used to produce electrical power from the wind. Operational experiences with these large rotating machines indicated that their components (primarily blades and blade joints) were failing at unexpectedly high rates, which led the wind turbine community to develop fatigue analysis capabilities for wind turbines. Our ability to analyze the fatigue behavior of wind turbine components has matured to the point that the prediction of service lifetime is becoming an essential part of the design process. In this review paper, I summarize the technology and describe the ''best practices'' for the fatigue analysis of a wind turbine component. The paper focuses on U.S. technology, but cites European references that provide important insights into the fatigue analysis of wind turbines.

Sutherland, Herbert J.

1999-06-01

25

Foundations for offshore wind turbines.  

PubMed

An important engineering challenge of today, and a vital one for the future, is to develop and harvest alternative sources of energy. This is a firm priority in the UK, with the government setting a target of 10% of electricity from renewable sources by 2010. A component central to this commitment will be to harvest electrical power from the vast energy reserves offshore, through wind turbines or current or wave power generators. The most mature of these technologies is that of wind, as much technology transfer can be gained from onshore experience. Onshore wind farms, although supplying 'green energy', tend to provoke some objections on aesthetic grounds. These objections can be countered by locating the turbines offshore, where it will also be possible to install larger capacity turbines, thus maximizing the potential of each wind farm location. This paper explores some civil-engineering problems encountered for offshore wind turbines. A critical component is the connection of the structure to the ground, and in particular how the load applied to the structure is transferred safely to the surrounding soil. We review previous work on the design of offshore foundations, and then present some simple design calculations for sizing foundations and structures appropriate to the wind-turbine problem. We examine the deficiencies in the current design approaches, and the research currently under way to overcome these deficiencies. Designs must be improved so that these alternative energy sources can compete economically with traditional energy suppliers. PMID:14667305

Byrne, B W; Houlsby, G T

2003-12-15

26

Build a Wind Turbine  

NSDL National Science Digital Library

Learners build a wind turbine and test it to see how much energy is created. Learners can build a variety of wind blades, test a variety of wind speeds and see what effect these have on the energy created. Adult supervision recommended.

Museum Of Science And Industry, Chicago

2012-01-01

27

Large, horizontal-axis wind turbines  

NASA Technical Reports Server (NTRS)

Development of the technology for safe, reliable, environmentally acceptable large wind turbines that have the potential to generate a significant amount of electricity at costs competitive with conventional electric generating systems are presented. In addition, these large wind turbines must be fully compatible with electric utility operations and interface requirements. There are several ongoing large wind system development projects and applied research efforts directed toward meeting the technology requirements for utility applications. Detailed information on these projects is provided. The Mod-O research facility and current applied research effort in aerodynamics, structural dynamics and aeroelasticity, composite and hybrid composite materials, and multiple system interaction are described. A chronology of component research and technology development for large, horizontal axis wind turbines is presented. Wind characteristics, wind turbine economics, and the impact of wind turbines on the environment are reported. The need for continued wind turbine research and technology development is explored. Over 40 references are sited and a bibliography is included.

Linscott, B. S.; Perkins, P.; Dennett, J. T.

1984-01-01

28

Wind Turbine Blade Design  

NSDL National Science Digital Library

Students go through the design process and the scientific method to test the effect of blade design on power output. There is an optional extension to use the data to create an optimal set of wind turbine blades.

Project, Kidwind

29

Vertical axis wind turbines  

DOEpatents

A vertical axis wind turbine is described. The wind turbine can include a top ring, a middle ring and a lower ring, wherein a plurality of vertical airfoils are disposed between the rings. For example, three vertical airfoils can be attached between the upper ring and the middle ring. In addition, three more vertical airfoils can be attached between the lower ring and the middle ring. When wind contacts the vertically arranged airfoils the rings begin to spin. By connecting the rings to a center pole which spins an alternator, electricity can be generated from wind.

Krivcov, Vladimir (Miass, RU); Krivospitski, Vladimir (Miass, RU); Maksimov, Vasili (Miass, RU); Halstead, Richard (Rohnert Park, CA); Grahov, Jurij (Miass, RU)

2011-03-08

30

Wind Turbine Blade Design  

NSDL National Science Digital Library

In this activity, learners design, build and test wind turbines. Learners go through the design process and use the scientific method to test important blade variables. Learners then use this data to create an optimal set of wind turbine blades. Educators can do the basic lesson in 3-4 class periods (about 3-4 hours) or extend the activity with a larger challenge that takes 5-7 class periods in total (about 5-7 hours).

Project, Kidwind

2006-01-01

31

Wind Turbine Blockset General Overview  

E-print Network

, optimize and design wind turbines". The report provides a quick overview of the Saber and then explainsWind Turbine Blockset in Saber General Overview and Description of the Models Florin Iov, Adrian Turbine Blockset in Saber Abstract. This report presents a new developed Saber Toolbox for wind turbine

32

Wind Turbine Acoustics  

NASA Technical Reports Server (NTRS)

Wind turbine generators, ranging in size from a few kilowatts to several megawatts, are producing electricity both singly and in wind power stations that encompass hundreds of machines. Many installations are in uninhabited areas far from established residences, and therefore there are no apparent environmental impacts in terms of noise. There is, however, the potential for situations in which the radiated noise can be heard by residents of adjacent neighborhoods, particularly those neighborhoods with low ambient noise levels. A widely publicized incident of this nature occurred with the operation of the experimental Mod-1 2-MW wind turbine, which is described in detail elsewhere. Pioneering studies which were conducted at the Mod-1 site on the causes and remedies of noise from wind turbines form the foundation of much of the technology described in this chapter.

Hubbard, Harvey H.; Shepherd, Kevin P.

2009-01-01

33

Wind tower augmentation of wind turbines  

Microsoft Academic Search

The operating principle of the 'Baud-Geers' wind towers traditionally used in Iran for ventilation and passive cooling of architectural structures is presently adapted to house a vertical axis wind turbine. Unlike annular diffuser-augmented, horizontal axis wind turbines, the 'wind tower' does not have to be trained into the wind and generates less noise. It may also be either free standing

M. N. Bahadori

1984-01-01

34

Design of wind turbine controller by using wind turbine codes  

Microsoft Academic Search

The wind turbine codes predict wind turbine loads and response in high accuracy and can be used in controller design with the development of the computer technologies. In this paper open source FAST code developed by NREL is studied. The wind turbine controller is designed in the Matlab\\/Simulink environment and the FAST code is modeled as an S-function. The simulation

Jianzhong Zhang; Ming Cheng; Zhe Chen

2008-01-01

35

Theory manual for FAROW version 1.1: A numerical analysis of the Fatigue And Reliability Of Wind turbine components  

SciTech Connect

Because the fatigue lifetime of wind turbine components depends on several factors that are highly variable, a numerical analysis tool called FAROW has been created to cast the problem of component fatigue life in a probabilistic framework. The probabilistic analysis is accomplished using methods of structural reliability (FORM/SORM). While the workings of the FAROW software package are defined in the user's manual, this theory manual outlines the mathematical basis. A deterministic solution for the time to failure is made possible by assuming analytical forms for the basic inputs of wind speed, stress response, and material resistance. Each parameter of the assumed forms for the inputs can be defined to be a random variable. The analytical framework is described and the solution for time to failure is derived.

WUBTERSTEUBMSTEVEB R.; VEERS,PAUL S.

2000-01-01

36

Wind Turbines on a Farm  

USGS Multimedia Gallery

Scientists have found that wind turbines are causing fatalities of certain species of migratory insect-eating bats, although a March 2011 study in Science suggests that solutions to reduce the impacts of wind turbines on bats may be possible....

37

Model Predictive Control Wind Turbines  

E-print Network

Model Predictive Control of Wind Turbines Martin Klauco Kongens Lyngby 2012 IMM-MSc-2012-65 #12;Summary Wind turbines are the biggest part of the green energy industry. Increasing interest control strategies. Control strategy has a significant impact on the wind turbine operation on many levels

38

Applied aerodynamics of wind turbines  

Microsoft Academic Search

This report covers hub fairings, Giromill, Darrieus Rotor, and the Super Induced (tipvanes). Hub fairings or spinners are frequently suggested for wind turbines for reasons of aesthetics or performance. While hub fairings rarely, if ever, decrease the appearance of a wind turbine, the effects of a nose fairing may actually decrease rather than increase wind turbine rotor performance. An analysis

R. E. Wilson; P. B. S. Lissaman; S. N. Walker; W. R. McKie

1977-01-01

39

Airborne Wind Turbine  

SciTech Connect

Broad Funding Opportunity Announcement Project: Makani Power is developing an Airborne Wind Turbine (AWT) that eliminates 90% of the mass of a conventional wind turbine and accesses a stronger, more consistent wind at altitudes of near 1,000 feet. At these altitudes, 85% of the country can offer viable wind resources compared to only 15% accessible with current technology. Additionally, the Makani Power wing can be economically deployed in deep offshore waters, opening up a resource which is 4 times greater than the entire U.S. electrical generation capacity. Makani Power has demonstrated the core technology, including autonomous launch, land, and power generation with an 8 meter wingspan, 20 kW prototype. At commercial scale, Makani Power aims to develop a 600 kW, 28 meter wingspan product capable of delivering energy at an unsubsidized cost competitive with coal, the current benchmark for low-cost power.

None

2010-09-01

40

Lightning protection system for a wind turbine  

DOEpatents

In a wind turbine (104, 500, 704) having a plurality of blades (132, 404, 516, 744) and a blade rotor hub (120, 712), a lightning protection system (100, 504, 700) for conducting lightning strikes to any one of the blades and the region surrounding the blade hub along a path around the blade hub and critical components of the wind turbine, such as the generator (112, 716), gearbox (708) and main turbine bearings (176, 724).

Costin, Daniel P. (Chelsea, VT); Petter, Jeffrey K. (Williston, VT)

2008-05-27

41

Tornado type wind turbines  

SciTech Connect

A tornado type wind turbine has a vertically disposed wind collecting tower with spaced apart inner and outer walls and a central bore. The upper end of the tower is open while the lower end of the structure is in communication with a wind intake chamber. An opening in the wind chamber is positioned over a turbine which is in driving communication with an electrical generator. An opening between the inner and outer walls at the lower end of the tower permits radially flowing air to enter the space between the inner and outer walls while a vertically disposed opening in the wind collecting tower permits tangentially flowing air to enter the central bore. A porous portion of the inner wall permits the radially flowing air to interact with the tangentially flowing air so as to create an intensified vortex flow which exits out of the top opening of the tower so as to create a low pressure core and thus draw air through the opening of the wind intake chamber so as to drive the turbine.

Hsu, Ch.-T.

1984-06-05

42

Wind turbine spoiler  

DOEpatents

An aerodynamic spoiler system for a vertical axis wind turbine includes spoilers on the blades initially stored near the rotor axis to minimize drag. A solenoid latch adjacent the central support tower releases the spoilers and centrifugal force causes the spoilers to move up the turbine blades away from the rotor axis, thereby producing a braking effect and actual slowing of the associated wind turbine, if desired. The spoiler system can also be used as an infinitely variable power control by regulated movement of the spoilers on the blades over the range between the undeployed and fully deployed positions. This is done by the use of a suitable powered reel and cable located at the rotor tower to move the spoilers.

Sullivan, William N. (Albuquerque, NM)

1985-01-01

43

Vertical axis wind turbines  

Microsoft Academic Search

A vertical axis wind turbine comprises one or more aerofoil section blades attached to a support structure. The blade has at least one part thereof which is acted on by centrifugal forces as the blade rotates with the support structure and thereby caused to increase its angle of inclination to the vertical axis when the speed of rotation increases beyond

Musgrove

1978-01-01

44

Vertical axis wind turbines  

Microsoft Academic Search

A vertical wind turbine having vertical blades, each blade being connected intermediate its ends by a hinge to a support arm having a hub that enables the blades to rotate around a vertical axis, a tie wire connected to the blade at positions spaced along the blade from the hinge, said tie wire engaging a spring-loaded pulley disposed inwardly of

P. E. Delgado; B. A. Holmes

1981-01-01

45

Advanced wind turbine conceptual study  

NASA Astrophysics Data System (ADS)

Objective was to develop improvements to an existing wind turbine that would make wind energy more competitive in 1993-1995, and to initiate studies of an advanced wind turbine configuration that would make wind energy competitive for bulk electricity generation by 1998-2000. Objective has been achieved.

1995-07-01

46

Build a Wind Turbine  

NSDL National Science Digital Library

This hands-on project provides step-by-step instructions for building a vertical axis wind turbine in secondary classrooms. The 17-page construction plans may be freely downloaded and are organized for first-time builders. Comprehensive background information on wind energy and renewable energy are provided. Registered teacher-users also have access to supporting lesson plans. All of the materials are readily available in hardware or grocery stores. This resource, which meets multiple national science standards, was developed to spark students' interest in learning more about renewable energy sources and the science and engineering principles that underlie the harnessing of renewable power. Editor's Note: Wind turbines work by using an internal generator to convert the mechanical energy of the spinning turbine shaft into electricity. This particular project is modeled after the Savonius rotor system, which uses uses drag -- not lift -- to capture energy for making electricity. Although it isn't as efficient as a conventional horizontal axis turbine, it is much easier to build.

2007-10-25

47

User`s manual for FAROW: Fatigue and reliability of wind turbine components: Version 1.1  

SciTech Connect

FAROW is a Computer program that assists in the probabilistic analysis of the Fatigue and Reliability of wind turbines. The fatigue lifetime of wind turbine components is calculated using functional forms for important input quantities. Parameters of these functions are defined in an input file as either constants or random variables. The user can select from a library of random variable distribution functions. FAROW uses structural reliability techniques to calculate the mean time to failure, probability of failure before a target lifetime, relative importance of each of the random inputs, and the sensitivity of the reliability to all input parameters. Monte Carlo simulation is also available. This user`s manual is intended to provide sufficient information to knowledgeably run the program and meaningfully interpret the results. The first chapter provides an overview of the approach and the results. Chapter 2 describes the formulation and assumptions used in the fatigue life calculations. Each of the input parameters is described in detail in Chapter 3 along with hints and warnings on usage. An explanation of the outputs is provided in Chapter 4. Two example problems are described and solved in Chapter 5, one for the case where extensive data are available and the other with limited data where the uncertainty is higher. A typical input file and the output files for the example problems are included in the appendices.

Veers, P.S. [Sandia National Labs., Albuquerque, NM (United States); Winterstein, S.R.; Lange, C.H. [Stanford Univ., Stanford, CA (United States). Dept. of Civil Engineering; Wilson, T.A. [New Mexico Univ., Albuquerque, NM (United States). Engineering Research Inst.

1994-11-01

48

Wind Turbine With Concentric Ducts  

NASA Technical Reports Server (NTRS)

Wind Turbine device is relatively compact and efficient. Converging inner and outer ducts increase pressure difference across blades of wind turbine. Turbine shaft drives alternator housed inside exit cone. Suitable for installation on such existing structures as water towers, barns, houses, and commercial buildings.

Muhonen, A. J.

1983-01-01

49

Wind turbine dynamics  

NASA Technical Reports Server (NTRS)

Recent progress in the analysis and prediction of the dynamic behavior of wind turbine generators is discussed. The following areas were addressed: (1) the adequacy of state of the art analysis tools for designing the next generation of wind power systems; (2) the use of state of the art analysis tools designers; and (3) verifications of theory which might be lacking or inadequate. Summaries of these informative discussions as well as the questions and answers which followed each paper are documented in the proceedings.

Thresher, R. W. (editor)

1981-01-01

50

The identification of inflow fluid dynamics parameters that can be used to scale fatigue loading spectra of wind turbine structural components  

SciTech Connect

We have recently shown that the alternating load fatigue distributions measured at several locations on a wind turbine operating in a turbulent flow can be described by a mixture of at least three parametric statistical models. The rainflow cycle counting of the horizontal and vertical inflow components results in a similar mixture describing the cyclic content of the wind. We believe such a description highlights the degree of non-Gaussian characteristics of the flow. We present evidence that the severity of the low-cycle, high-amplitude alternating stress loads seen by wind turbine components are a direct consequence of the degree of departure from normality in the inflow. We have examined the details of the turbulent inflow associated with series large loading events that took place on two adjacent wind turbines installed in a large wind park in San Gorgonio Pass, California. In this paper, we describe what we believe to be the agents in the flow that induced such events. We also discuss the atmospheric mechanisms that influence the low-cycle, high-amplitude range loading seen by a number of critical wind turbine components. We further present results that can be used to scale the specific distribution shape as functions of measured inflow fluid dynamics parameters.

Kelley, N.D.

1993-11-01

51

Airfoils for wind turbine  

DOEpatents

Airfoils are disclosed for the blade of a wind turbine wherein each airfoil is characterized by a thickness in a range from 16%-24% and a maximum lift coefficient designed to be largely insensitive to roughness effects. The airfoils include a family of airfoils for a blade 15 to 25 meters in length, a family of airfoils for a blade 1 to 5 meters in length, and a family of airfoils for a blade 5 to 10 meters in length. 10 figs.

Tangler, J.L.; Somers, D.M.

1996-10-08

52

Airfoils for wind turbine  

DOEpatents

Airfoils for the blade of a wind turbine wherein each airfoil is characterized by a thickness in a range from 16%-24% and a maximum lift coefficient designed to be largely insensitive to roughness effects. The airfoils include a family of airfoils for a blade 15 to 25 meters in length, a family of airfoils for a blade 1 to 5 meters in length, and a family of airfoils for a blade 5 to 10 meters in length.

Tangler, James L. (Boulder, CO); Somers, Dan M. (State College, PA)

1996-01-01

53

Sandhill Cranes Near Wind Turbines  

USGS Multimedia Gallery

Sandhill Cranes fly in close proximity to wind turbines near Horicon National Wildlife Refuge in east-central Wisconsin, but to date no crane mortality has been associated with turbines in this area....

54

Make Your Own Wind Turbine  

NSDL National Science Digital Library

In this activity, learners create a wind turbine model using a simple pattern, a thumbtack, and a pencil with an eraser. After constructing the model, learners blow on the wind turbine to simulate the wind. Use this activity to introduce alternative energy and electricity generation.

History, National M.

2012-06-26

55

Wind Turbine Contingency Control Through Generator De-Rating  

NASA Technical Reports Server (NTRS)

Maximizing turbine up-time and reducing maintenance costs are key technology drivers for wind turbine operators. Components within wind turbines are subject to considerable stresses due to unpredictable environmental conditions resulting from rapidly changing local dynamics. In that context, systems health management has the aim to assess the state-of-health of components within a wind turbine, to estimate remaining life, and to aid in autonomous decision-making to minimize damage to the turbine. Advanced contingency control is one way to enable autonomous decision-making by providing the mechanism to enable safe and efficient turbine operation. The work reported herein explores the integration of condition monitoring of wind turbines with contingency control to balance the trade-offs between maintaining system health and energy capture. The contingency control involves de-rating the generator operating point to achieve reduced loads on the wind turbine. Results are demonstrated using a high fidelity simulator of a utility-scale wind turbine.

Frost, Susan; Goebel, Kai; Balas, Mark

2013-01-01

56

Wind Power! Designing a Wind Turbine  

NSDL National Science Digital Library

Students learn how engineers transform wind energy into electrical energy by building their own miniature wind turbines and measuring the electrical current it produces. They explore how design and position affect the electrical energy production.

Integrated Teaching And Learning Program

57

Wind response characteristics of horizontal axis wind turbines  

NASA Technical Reports Server (NTRS)

It was the objective of the work reported here, and in the companion paper 1 . A broader examination of wind turbine dynamic response to turbulence, and attempts to ascertain the features of turbulence that wind turbines are most sensitive to were made. A statistical description of the wind input including all three wind components and allowing linear wind gradients across the rotor disk, was used together with quasi-static aerodynamic theory and an elementary structural model involving only a few degrees of freedom. The idea was to keep the turbine model simple and show the benefits of this type of statistical wind representation before attempting to use a more complex turbine model. As far as possible, the analysis was kept in the simplest form, while still preserving key physical responses.

Thresher, R. W.; Holley, W. E.; Jafarey, N.

1981-01-01

58

Lightning protection of wind turbines  

NASA Technical Reports Server (NTRS)

Possible damages to wind turbine components due to lightning strikes are discussed and means to prevent the damage are presented. A low resistance path to the ground is noted to be essential for any turbine system, including metal paths on nonmetal blades to conduct the strike. Surge arrestors are necessary to protect against overvoltages both from utility lines in normal operation and against lightning damage to control equipment and contactors in the generator. MOS structures are susceptible to static discharge injury, as are other semiconductor devices, and must be protected by the presence of static protection circuitry. It is recommended that the electronics be analyzed for the circuit transient response to a lightning waveform, to induced and dc current injection, that input/output leads be shielded, everything be grounded, and lightning-resistant components be chosen early in the design phase.

Dodd, C. W.

1982-01-01

59

Large-scale wind turbine structures  

NASA Technical Reports Server (NTRS)

The purpose of this presentation is to show how structural technology was applied in the design of modern wind turbines, which were recently brought to an advanced stage of development as sources of renewable power. Wind turbine structures present many difficult problems because they are relatively slender and flexible; subject to vibration and aeroelastic instabilities; acted upon by loads which are often nondeterministic; operated continuously with little maintenance in all weather; and dominated by life-cycle cost considerations. Progress in horizontal-axis wind turbines (HAWT) development was paced by progress in the understanding of structural loads, modeling of structural dynamic response, and designing of innovative structural response. During the past 15 years a series of large HAWTs was developed. This has culminated in the recent completion of the world's largest operating wind turbine, the 3.2 MW Mod-5B power plane installed on the island of Oahu, Hawaii. Some of the applications of structures technology to wind turbine will be illustrated by referring to the Mod-5B design. First, a video overview will be presented to provide familiarization with the Mod-5B project and the important components of the wind turbine system. Next, the structural requirements for large-scale wind turbines will be discussed, emphasizing the difficult fatigue-life requirements. Finally, the procedures used to design the structure will be presented, including the use of the fracture mechanics approach for determining allowable fatigue stresses.

Spera, David A.

1988-01-01

60

Wind tunnel investigation on wind turbine wakes and wind farms  

NASA Astrophysics Data System (ADS)

The interaction between atmospheric boundary layer and wind farms leads to flow modifications, which need to be deeply characterized in order to relate them to wind farm performance. The wake flow produced from a wind farm is the result of a strong interaction between multiple turbine wakes, so that the wind farm configuration turns out to be one of the dominant features to enhance power production. For the present work a wind tunnel investigation was carried out with hot-wire anemometry and velocity measurements performed with multi-hole pressure probes. The tested wind farms consist of miniature three-bladed wind turbine models. Preliminarily, the wake flow generated from a single wind turbine is surveyed, which is characterized by a strong velocity defect lying in proximity of the wind turbine hub height. The wake gradually recovers by moving downstream; the characteristics of the incoming boundary layer and wind turbulence intensity can strongly affect the wake recovery, and thus performance of following wind turbines. An increased turbulence level is typically detected downstream of each wind turbine for heights comparable to the wind turbine blade top-tip. These wake flow fluctuations produce increased fatigue loads on the following wind turbines within a wind farm, which could represent a significant hazard for real wind turbines. Dynamics of vorticity structures present in wind turbine wakes are also investigated; particular attention is paid to the downstream evolution of the tip helicoidal vortices and to oscillations of the hub vortex. The effect of wind farm layout on power production is deeply investigated. Particular emphasis is placed on studying how the flow adjusts as it moves inside the wind farm and can affect the power production. Aligned and staggered wind farm configurations are analysed, also with varying separation distances in the streamwise and spanwise directions. The present experimental results are being used to test and guide the development of improved parameterizations of wind turbines in high-resolution numerical models, such as large-eddy simulations (LES).

Iungo, G. V.; Coëffé, J.; Porté-Agel, F.

2012-04-01

61

Wind Turbines Adaptation to the Variability of the Wind Field  

NASA Astrophysics Data System (ADS)

WIND TURBINES ADAPTATION TO THE VARIABILITY OF THE WIND FIELD The subject of our scientific research is wind power turbines (WPT) with the horizontal axis which were now common in the world. Efficient wind turbines work is largely determined by non-stationarity of the wind field, expressed in its gustiness, the presence of vertical and horizontal shifts of wind speed and direction. At critical values of the wind parameters WPT has aerodynamic and mechanical overload, leading to breakdowns, premature wear and reduce the life of the wind turbine. To prevent accidents at the peak values of wind speed it is used the regulatory system of windwheels. WPT control systems provide a process orientation of the wind turbine rotor axis in the line of the mean wind. Wind turbines are also equipped with braking device used to protect against breakdowns when a significant increase in the wind. In general, all these methods of regulation are not always effective. Thus, in practice there may be situations when the wind speed is many times greater than the stated limit. For example, if there are microbursts in the atmospheric boundary layer, low-level wind shears caused by its gust front, storms, etc. It is required for a wind power turbine adaptation to intensive short-term wind impulses and considerable vertical wind shifts that the data about them shall be obtained ahead of time. To do this it is necessary to have the information on the real structure of the wind field in the area of the blade sweep for the minimum range against the wind that is determined by the mean speed and the system action time. The implementation of acoustic and laser traditional wind sounding systems is limited by ambient acoustic noise, by heavy rain, snowfall and by fog. There are free of these disadvantages the inclined radioacoustic sounding (IRASS) technique which works for a system of remote detection and control of wind gusts. IRASS technique is realized as low-potential Doppler pulse radar including combined RF-acoustic antenna installed coaxially with the gondola of the wind power turbine. The work of the technique is synchronized with rotation of blades to eliminate their shielding action. Dangerous in terms of dynamic strength is the wind load pulse, the rise time which is comparable with the period of the natural frequency of the wind turbine elements (blade, tower, rotor, etc.). The amplitude decay of resonant vibrations at critical values of the speed of rotation can be realized through the use of mechanical elastic supports with nonlinear artificial dampers. They have a high coefficient of resistance, but may cause self-excited oscillations. We propose the way to deal with raised vibration of wind turbine elements at the expense of short-term increase of damping in the range of critical rotary axis speeds or during impulsive effects of wind loadings (wind gusts). This is possible through the use of non-linear electromagnetic dampers or active magnetic bearings. Their feature is the possibility of varying the mechanical stiffness and damping properties by changing the electrical parameters of electromagnets. The controlling of these parameters is carried out by the control system (CS) with the information feedback on the spatial-temporal structure of the wind field obtained from IRASS. In the composition of the CS can also be included the rotational speed sensor of the WPT rotor. This approach to the adaptation of wind turbines will allow to reduce vibration and to perform early compensation of the load on their components, which arise under the wind gusts. In addition, corrections about the wind field obtained with IRASS, would increase the mean power of WPT.

Ulianov, Yuriy; Martynenko, Gennadii; Misaylov, Vitaliy; Soliannikova, Iuliia

2010-05-01

62

PowerJet Wind Turbine Project  

SciTech Connect

PROJECT OBJECTIVE The PowerJet wind turbine overcomes problems characteristic of the small wind turbines that are on the market today by providing reliable output at a wide range of wind speeds, durability, silent operation at all wind speeds, and bird-safe operation. Prime Energy�s objective for this project was to design and integrate a generator with an electrical controller and mechanical controls to maximize the generation of electricity by its wind turbine. The scope of this project was to design, construct and test a mechanical back plate to control rotational speed in high winds, and an electronic controller to maximize power output and to assist the base plate in controlling rotational speed in high winds. The test model will continue to operate beyond the time frame of the project, with the ultimate goal of manufacturing and marketing the PowerJet worldwide. Increased Understanding of Electronic & Mechanical Controls Integrated With Electricity Generator The PowerJet back plate begins to open as wind speed exceeds 13.5 mps. The pressure inside the turbine and the turbine rotational speed are held constant. Once the back plate has fully opened at approximately 29 mps, the controller begins pulsing back to the generator to limit the rotational speed of the turbine. At a wind speed in excess of 29 mps, the controller shorts the generator and brings the turbine to a complete stop. As the wind speed subsides, the controller releases the turbine and it resumes producing electricity. Data collection and instrumentation problems prevented identification of the exact speeds at which these events occur. However, the turbine, controller and generator survived winds in excess of 36 mps, confirming that the two over-speed controls accomplished their purpose. Technical Effectiveness & Economic Feasibility Maximum Electrical Output The output of electricity is maximized by the integration of an electronic controller and mechanical over-speed controls designed and tested during the course of this project. The output exceeds that of the PowerJet�s 3-bladed counterparts (see Appendix). Durability All components of the PowerJet turbine assembly�including the electronic and mechanical controls designed, manufactured and field tested during the course of this project�proved to be durable through severe weather conditions, with constant operation and no interruption in energy production. Low Cost Materials for the turbine, generator, tower, charge controllers and ancillary parts are available at reasonable prices. Fabrication of these parts is also readily available worldwide. The cost of assembling and installing the turbine is reduced because it has fewer parts and requires less labor to manufacture and assemble, making it competitively priced compared with turbines of similar output manufactured in the U.S. and Europe. The electronic controller is the unique part to be included in the turbine package. The controllers can be manufactured in reasonably-sized production runs to keep the cost below $250 each. The data logger and 24 sensors are for research only and will be unnecessary for the commercial product. Benefit To Public The PowerJet wind-electric system is designed for distributed wind generation in 3 and 4 class winds. This wind turbine meets DOE�s requirements for a quiet, durable, bird-safe turbine that eventually can be deployed as a grid-connected generator in urban and suburban settings. Results As described more fully below and illustrated in the Appendices, the goals and objectives outlined in 2060 SOPO were fully met. Electronic and mechanical controls were successfully designed, manufactured and integrated with the generator. The turbine, tower, controllers and generators operated without incident throughout the test period, surviving severe winter and summer weather conditions such as extreme temperatures, ice and sustained high winds. The electronic controls were contained in weather-proof electrical boxes and the elec

Bartlett, Raymond J

2008-11-30

63

Wind turbine rotor aileron  

DOEpatents

A wind turbine has a rotor with at least one blade which has an aileron which is adjusted by an actuator. A hinge has two portions, one for mounting a stationary hinge arm to the blade, the other for coupling to the aileron actuator. Several types of hinges can be used, along with different actuators. The aileron is designed so that it has a constant chord with a number of identical sub-assemblies. The leading edge of the aileron has at least one curved portion so that the aileron does not vent over a certain range of angles, but vents if the position is outside the range. A cyclic actuator can be mounted to the aileron to adjust the position periodically. Generally, the aileron will be adjusted over a range related to the rotational position of the blade. A method for operating the cyclic assembly is also described.

Coleman, Clint (Warren, VT); Kurth, William T. (Warren, VT)

1994-06-14

64

Vertical axis wind turbines  

SciTech Connect

A vertical wind turbine having vertical blades, each blade being connected intermediate its ends by a hinge to a support arm having a hub that enables the blades to rotate around a vertical axis, a tie wire connected to the blade at positions spaced along the blade from the hinge, said tie wire engaging a spring-loaded pulley disposed inwardly of the blades, the arrangement being such that when the angle of inclination of the blades to the vertical axis alters under the action of centrifugal force the tie wire exerts a force on the pulley opposing the spring force whereby as the turbine speeds up the blades will remain at a predetermined angle of inclination until the force exerted by the wire exceeds the force of the spring. One end of the tie wire can be connected to a position on one blade and connected to another position on another blade so that all of the blades adopt the same angle of inclination to the vertical axis.

Delgado, P.E.; Holmes, B.A.

1981-06-23

65

SERI advanced wind turbine blades  

SciTech Connect

The primary goal of the Solar Energy Research Institute`s (SERI) advanced wind turbine blades is to convert the kinetic energy in the wind into mechanical energy in an inexpensive and efficient manner. To accomplish this goal, advanced wind turbine blades have been developed by SERI that utilize unique airfoil technology. Performance characteristics of the advanced blades were verified through atmospheric testing on fixed-pitch, stall-regulated horizontal-axis wind turbines (HAWTs). Of the various wind turbine configurations, the stall-regulated HAWT dominates the market because of its simplicity and low cost. Results of the atmospheric tests show that the SERI advanced blades produce 10% to 30% more energy than conventional blades. 6 refs.

Tangler, J.; Smith, B.; Jager, D.

1992-02-01

66

SERI advanced wind turbine blades  

SciTech Connect

The primary goal of the Solar Energy Research Institute's (SERI) advanced wind turbine blades is to convert the kinetic energy in the wind into mechanical energy in an inexpensive and efficient manner. To accomplish this goal, advanced wind turbine blades have been developed by SERI that utilize unique airfoil technology. Performance characteristics of the advanced blades were verified through atmospheric testing on fixed-pitch, stall-regulated horizontal-axis wind turbines (HAWTs). Of the various wind turbine configurations, the stall-regulated HAWT dominates the market because of its simplicity and low cost. Results of the atmospheric tests show that the SERI advanced blades produce 10% to 30% more energy than conventional blades. 6 refs.

Tangler, J.; Smith, B.; Jager, D.

1992-02-01

67

Effective Lightning Protection For Wind Turbine Generators  

Microsoft Academic Search

A wind turbine generator is the most exposed of all types of generators connected to electric utility systems. Wind turbines are most often erected in hostile lightning environments. Lightning damage to wind turbines is costly in terms of repair and replacement of equipment. Lightning damage is the single largest cause of unplanned downtime in wind turbines, and that downtime is

Bruce Glushakow

2007-01-01

68

Fatigue and reliability analyses for wind turbines  

NASA Astrophysics Data System (ADS)

This paper presents a summary of two areas of research into the fatigue of wind turbine components at Sandia National Laboratories. The first area is the fatigue analysis of turbine components and the second is reliability analysis. For the former, current work is addressing the examination of experimental data in the time and frequency domain. Emphasis in this paper is directed at the determination of the 'high-stress' tail of the cycle count distribution. For the reliability analysis, research is quantifying the uncertainties and the inherent randomness associated with turbine performance and the prediction of service lifetimes. Both research areas are highlighted with typical results.

Sutherland, H. J.

69

Analysis of the Environmental Impact on Remanufacturing Wind Turbines  

NASA Astrophysics Data System (ADS)

To deliver clean energy the use of wind turbines is essential. In June 2011 there was an installed wind capacity equivalent to 211,000MW world-wide (WWEA, 2011). By the end of the year 2009 the U.S. had 35,100MW of wind energy installed capacity to generate electricity (AWEA, 2010). This industry has grown in recent years and is expected to grow even more in the future. The environmental impacts that will arise from the increased number of wind turbines and their end-of-life should be addressed, as large amounts of resources will be required to satisfy the current and future market demands for wind turbines. Since future 10MW wind turbines are expected to be as heavy as 1000 tons each, the study of the environmental response of profitable retirement strategies, such as remanufacturing for these machines, must be considered. Because of the increased number of wind turbines and the materials used, this study provides a comparison between the environmental impacts from remanufacturing the components installed inside the nacelle of multi-megawatt wind turbines and wind turbines manufactured using new components. The study methodology is the following: • Describe the life-cycle and the materials and processes employed for the manufacture and remanufacturing for components inside the nacelle. • Identify remanufacturing alternatives for the components inside the nacelle at the end of the expected life-time service of wind turbines. • Evaluate the environmental impacts from the remanufactured components and compare the results with the impacts of the manufacturing of new components using SimaPro. • Conduct sensitivity analysis over the critical parameters of the life cycle assessment • Propose the most environmentally friendly options for the retirement of each major component of wind turbines. After an analysis of the scenarios the goal of the study is to evaluate remanufacturing as an end-of-life option from an environmental perspective for commercial multi-megawatt wind turbines targeted for secondary wind turbine markets.

Sosa Skrainka, Manuel R.

70

Parametric design of floating wind turbines  

E-print Network

As the price of energy increases and wind turbine technology matures, it is evident that cost effective designs for floating wind turbines are needed. The next frontier for wind power is the ocean, yet development in near ...

Tracy, Christopher (Christopher Henry)

2007-01-01

71

Wind Turbine Certification and Type Certification Guideline for the Certification of Wind Turbines, Edition 2003 with Supplement 2004  

Microsoft Academic Search

Certification of wind turbines or components is state-of-the-art and a must in most places around the world. Furthermore certification to harmonised requirements is an active support of export. Therefore it is important for manufacturers, banks and insurances of wind turbines and components to know the different certification processes as well as guidelines. The procedures to obtain Type and Project Certificates

Mike Woebbeking; Christian Nath; Germanischer Lloyd

72

Sprayed skin turbine component  

DOEpatents

Fabricating a turbine component (50) by casting a core structure (30), forming an array of pits (24) in an outer surface (32) of the core structure, depositing a transient liquid phase (TLP) material (40) on the outer surface of the core structure, the TLP containing a melting-point depressant, depositing a skin (42) on the outer surface of the core structure over the TLP material, and heating the assembly, thus forming both a diffusion bond and a mechanical interlock between the skin and the core structure. The heating diffuses the melting-point depressant away from the interface. Subsurface cooling channels (35) may be formed by forming grooves (34) in the outer surface of the core structure, filling the grooves with a fugitive filler (36), depositing and bonding the skin (42), then removing the fugitive material.

Allen, David B

2013-06-04

73

MOD-2 wind turbine development  

NASA Technical Reports Server (NTRS)

The development of the Mod-2 turbine, designed to achieve a cost of electricity for the 100th production unit that will be competitive with conventional electric power generation is discussed. The Mod-2 wind turbine system (WTS) background, project flow, and a chronology of events and problem areas leading to Mod-2 acceptance are addressed. The role of the participating utility during site preparation, turbine erection and testing, remote operation, and routine operation and maintenance activity is reviewed. The technical areas discussed pertain to system performance, loads, and controls. Research and technical development of multimegawatt turbines is summarized.

Gordon, L. H.; Andrews, J. S.; Zimmerman, D. K.

1983-01-01

74

Unavailability of wind turbines due to wind-induced accelerations  

Microsoft Academic Search

The malfunctioning of acceleration-sensitive equipment in wind turbines has the potential to affect their annual failure rates during normal operating conditions. Current protective measures for wind turbines are triggered by wind speed. However, this option neglects the structural response of the wind turbines, and limits the possibility of effectively controlling accelerations at the top of the wind towers. In this

Leonardo Dueñas-Osorio; Biswajit Basu

2008-01-01

75

Vertical axis wind turbine motor  

Microsoft Academic Search

A wind power conversion turbine motor has a body supported to rotate about a vertical axis and carrying a plurality of substantially upright vanes substantially spaced from the vertical axis and circumferentially spaced from one another so that wind thrusting propulsively against outer sides of the vanes can move across the space circumscribed by the vanes and thrust propulsively against

Rumsey

1977-01-01

76

the risk issue of wind measurement for wind turbine operation  

E-print Network

-related issues on wind turbine operation 3/31/2011 2 #12;WIND MEASUREMENT IN METEOROLOGY & WIND FARM DESIGN 3the risk issue of wind measurement for wind turbine operation Po-Hsiung Lin Dept. of Atmospheric Sciences, National Taiwan University #12;outline · Wind measurement in meteorology and wind farm design

Leu, Tzong-Shyng "Jeremy"

77

Sandia Wind Turbine Loads Database  

DOE Data Explorer

The Sandia Wind Turbine Loads Database is divided into six files, each corresponding to approximately 16 years of simulation. The files are text files with data in columnar format. The 424MB zipped file containing six data files can be downloaded by the public. The files simulate 10-minute maximum loads for the NREL 5MW wind turbine. The details of the loads simulations can be found in the paper: “Decades of Wind Turbine Loads Simulations”, M. Barone, J. Paquette, B. Resor, and L. Manuel, AIAA2012-1288 (3.69MB PDF). Note that the site-average wind speed is 10 m/s (class I-B), not the 8.5 m/s reported in the paper.

78

Fast Wind Turbine Design via Geometric Programming  

E-print Network

Fast Wind Turbine Design via Geometric Programming Warren Hoburg and Pieter Abbeel UC Berkeley the application of GP to large wind turbine design problems a promising approach. Nomenclature (·)a, (·)t axial the wind sector's annual turnover of $65 Billion, optimal design of wind turbines is a problem of great

Abbeel, Pieter

79

Wind turbine reliability : understanding and minimizing wind turbine operation and maintenance costs.  

SciTech Connect

Wind turbine system reliability is a critical factor in the success of a wind energy project. Poor reliability directly affects both the project's revenue stream through increased operation and maintenance (O&M) costs and reduced availability to generate power due to turbine downtime. Indirectly, the acceptance of wind-generated power by the financial and developer communities as a viable enterprise is influenced by the risk associated with the capital equipment reliability; increased risk, or at least the perception of increased risk, is generally accompanied by increased financing fees or interest rates. Cost of energy (COE) is a key project evaluation metric, both in commercial applications and in the U.S. federal wind energy program. To reflect this commercial reality, the wind energy research community has adopted COE as a decision-making and technology evaluation metric. The COE metric accounts for the effects of reliability through levelized replacement cost and unscheduled maintenance cost parameters. However, unlike the other cost contributors, such as initial capital investment and scheduled maintenance and operating expenses, costs associated with component failures are necessarily speculative. They are based on assumptions about the reliability of components that in many cases have not been operated for a complete life cycle. Due to the logistical and practical difficulty of replacing major components in a wind turbine, unanticipated failures (especially serial failures) can have a large impact on the economics of a project. The uncertainty associated with long-term component reliability has direct bearing on the confidence level associated with COE projections. In addition, wind turbine technology is evolving. New materials and designs are being incorporated in contemporary wind turbines with the ultimate goal of reducing weight, controlling loads, and improving energy capture. While the goal of these innovations is reduction in the COE, there is a potential impact on reliability whenever new technologies are introduced. While some of these innovations may ultimately improve reliability, in the short term, the technology risks and the perception of risk will increase. The COE metric used by researchers to evaluate technologies does not address this issue. This paper outlines the issues relevant to wind turbine reliability for wind turbine power generation projects. The first sections describe the current state of the industry, identify the cost elements associated with wind farm O&M and availability and discuss the causes of uncertainty in estimating wind turbine component reliability. The latter sections discuss the means for reducing O&M costs and propose O&M related research and development efforts that could be pursued by the wind energy research community to reduce COE.

Not Available

2004-11-01

80

Wind Turbines and Human Health  

PubMed Central

The association between wind turbines and health effects is highly debated. Some argue that reported health effects are related to wind turbine operation [electromagnetic fields (EMF), shadow flicker, audible noise, low-frequency noise, infrasound]. Others suggest that when turbines are sited correctly, effects are more likely attributable to a number of subjective variables that result in an annoyed/stressed state. In this review, we provide a bibliographic-like summary and analysis of the science around this issue specifically in terms of noise (including audible, low-frequency noise, and infrasound), EMF, and shadow flicker. Now there are roughly 60 scientific peer-reviewed articles on this issue. The available scientific evidence suggests that EMF, shadow flicker, low-frequency noise, and infrasound from wind turbines are not likely to affect human health; some studies have found that audible noise from wind turbines can be annoying to some. Annoyance may be associated with some self-reported health effects (e.g., sleep disturbance) especially at sound pressure levels >40?dB(A). Because environmental noise above certain levels is a recognized factor in a number of health issues, siting restrictions have been implemented in many jurisdictions to limit noise exposure. These setbacks should help alleviate annoyance from noise. Subjective variables (attitudes and expectations) are also linked to annoyance and have the potential to facilitate other health complaints via the nocebo effect. Therefore, it is possible that a segment of the population may remain annoyed (or report other health impacts) even when noise limits are enforced. Based on the findings and scientific merit of the available studies, the weight of evidence suggests that when sited properly, wind turbines are not related to adverse health. Stemming from this review, we provide a number of recommended best practices for wind turbine development in the context of human health. PMID:24995266

Knopper, Loren D.; Ollson, Christopher A.; McCallum, Lindsay C.; Whitfield Aslund, Melissa L.; Berger, Robert G.; Souweine, Kathleen; McDaniel, Mary

2014-01-01

81

An examination of loads and responses of a wind turbine undergoing variable-speed operation  

Microsoft Academic Search

The National Renewable Energy Laboratory has recently developed the ability to predict turbine loads and responses for machines undergoing variable-speed operation. The wind industry has debated the potential benefits of operating wind turbine sat variable speeds for some time. Turbine system dynamic responses (structural response, resonance, and component interactions) are an important consideration for variable-speed operation of wind turbines. The

A. D. Wright; M. L. Jr. Buhl; G. S. Bir

1996-01-01

82

Wind turbine reliability :understanding and minimizing wind turbine operation and maintenance costs.  

SciTech Connect

Wind turbine system reliability is a critical factor in the success of a wind energy project. Poor reliability directly affects both the project's revenue stream through increased operation and maintenance (O&M) costs and reduced availability to generate power due to turbine downtime. Indirectly, the acceptance of wind-generated power by the financial and developer communities as a viable enterprise is influenced by the risk associated with the capital equipment reliability; increased risk, or at least the perception of increased risk, is generally accompanied by increased financing fees or interest rates. This paper outlines the issues relevant to wind turbine reliability for wind turbine power generation projects. The first sections describe the current state of the industry, identify the cost elements associated with wind farm O&M and availability and discuss the causes of uncertainty in estimating wind turbine component reliability. The latter sections discuss the means for reducing O&M costs and propose O&M related research and development efforts that could be pursued by the wind energy research community to reduce cost of energy.

Walford, Christopher A. (Global Energy Concepts. Kirkland, WA)

2006-03-01

83

Towards Data-Driven Control for Modern Wind Turbines  

Microsoft Academic Search

Further developments in data-driven control techniques for the load reduction of modern wind turbines can achieve an increased lifetime of components and make the scaling to larger rotor diameters possible, and therefore improve the cost effectiveness of modern wind turbines. Also the success of future rotor designs will heavily depend for their operation on new developments in active control technologies.

I. Houtzager

2011-01-01

84

Vertical axis wind turbine airfoil  

DOEpatents

A vertical axis wind turbine airfoil is described. The wind turbine airfoil can include a leading edge, a trailing edge, an upper curved surface, a lower curved surface, and a centerline running between the upper surface and the lower surface and from the leading edge to the trailing edge. The airfoil can be configured so that the distance between the centerline and the upper surface is the same as the distance between the centerline and the lower surface at all points along the length of the airfoil. A plurality of such airfoils can be included in a vertical axis wind turbine. These airfoils can be vertically disposed and can rotate about a vertical axis.

Krivcov, Vladimir; Krivospitski, Vladimir; Maksimov, Vasili; Halstead, Richard; Grahov, Jurij Vasiljevich

2012-12-18

85

Optimizing wind turbine control system parameters  

SciTech Connect

The impending expiration of the levelized period in the Interim Standard Offer Number 4 (ISO4) utility contracts for purchasing wind-generated power in California mandates, more than ever, that windplants be operated in a cost-effective manner. Operating plans and approaches are needed that maximize the net revenue from wind parks--after accounting for operation and maintenance costs. This paper describes a design tool that makes it possible to tailor a control system of a wind turbine (WT) to maximize energy production while minimizing the financial consequences of fatigue damage to key structural components. Plans for code enhancements to include expert systems and fuzzy logic are discussed, and typical results are presented in which the code is applied to study the controls of a generic Danish 15-m horizontal axis wind turbine (HAWT).

Schluter, L.L. [Sandia National Labs., Albuquerque, NM (United States); Vachon, W.A. [Vachon (W.A.) and Associates, Inc., Manchester, MA (United States)

1993-08-01

86

Vertical axis wind turbine foundation parameter study  

NASA Astrophysics Data System (ADS)

The foundation/anchor requirements for the Vertical Axis Wind Turbine are identified. Information is supplied concerning the selection, design, and cost estimates for the geologic conditions which may be encountered at potential wind turbine sites.

Ludde, P. F.

1980-07-01

87

Wind turbine emulator using wind turbine model based on blade element momentum theory  

Microsoft Academic Search

This paper presents the wind turbine emulator using the wind turbine model based on blade element momentum theory. The lift coefficient cl and drag coefficient cd of designed blade shape are calculated with the fluid analysis. Therefore the proposed wind turbine emulator can emulate the new designed windmill without manufacturing. Also the wind turbine model considers the mechanical model and

K. Ohyama; T. Nakashima

2010-01-01

88

Wind Turbine Drivetrain Condition Monitoring - An Overview (Presentation)  

SciTech Connect

High operation and maintenance costs still hamper the development of the wind industry despite its quick growth worldwide. To reduce unscheduled downtime and avoid catastrophic failures of wind turbines and their components have been and will be crucial to further raise the competitiveness of wind power. Condition monitoring is one of the key tools for achieving such a goal. To enhance the research and development of advanced condition monitoring techniques dedicated to wind turbines, we present an overview of wind turbine condition monitoring, discuss current practices, point out existing challenges, and suggest possible solutions.

Sheng, S.; Yang, W.

2013-07-01

89

A Fatigue Approach to Wind Turbine Control  

E-print Network

. Therefore, fatigue damage is a major consideration when designing wind turbines. The control scheme applied University of Denmark. The thesis deals with wind turbine controller design taking into account fatigue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.2 Wind turbine design . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.3 Thesis structure . . . . . . . . . . . . . . . . . . . .

90

Wind Turbine Blockset in Matlab/Simulink  

E-print Network

to model, optimize and design wind turbines" and it has been used as a general developer tool for otherWind Turbine Blockset in Matlab/Simulink General Overview and Description of the Models Florin Iov, Anca Daniela Hansen, Poul Sørensen, Frede Blaabjerg Aalborg University March 2004 #12;22 Wind Turbine

91

Wind turbine testing. Final report  

SciTech Connect

Los Alamos National Laboratory (LANL) is investigating concepts for removing heat from nuclear material storage units. One method which has been suggested is the use of wind turbine ventilators on the roofs of the units. An advantage of these devices is that it would require no power to operate them, and in this sense the system would be fail safe. The internal heat in the storage units would naturally cause air to rise through the ventilators and the usually prevailing winds which average about 5 mph would combine with the buoyancy to exhaust the air from the units. However, it was not known whether these type of ventilators can deliver a sufficient air flow through the High Efficiency Particulate Air (HEPA) filters which must be an integral part of the ventilation system in a nuclear storage facility. Therefore, this study was undertaken to answer that question. In this report we will discuss the experiments which were run on two wind turbine ventilators, one with a one foot diameter inlet duct and one with a two foot diameter inlet duct. The wind turbines were supplied by LANL and tested in the New Mexico State University/LANL wind binnel housed in the Mechanical Engineering Department on the Las Cruces Campus of NMSU. The experiments were run at a nominal wind speed of 5 mph, with and without heating below the ventilator inlet and with and without resistance elements at the ventilator inlet.

Smith, P.R.

1995-01-01

92

Electromagnetic interference from wind turbines  

Microsoft Academic Search

Summary form only given. During the late nineteen seventies and eighties the University of Michigan Radiation Laboratory, under sponsorship from the US Department of Energy, studied theoretically and experimentally the effects of wind turbines (WTs) on the performance of various electromagnetic systems. The article summarizes selected portions of the fundamental work carried out and techniques developed under the program which

D. L. Sengupta

1999-01-01

93

Probabilistic fatigue methodology and wind turbine reliability  

SciTech Connect

Wind turbines subjected to highly irregular loadings due to wind, gravity, and gyroscopic effects are especially vulnerable to fatigue damage. The objective of this study is to develop and illustrate methods for the probabilistic analysis and design of fatigue-sensitive wind turbine components. A computer program (CYCLES) that estimates fatigue reliability of structural and mechanical components has been developed. A FORM/SORM analysis is used to compute failure probabilities and importance factors of the random variables. The limit state equation includes uncertainty in environmental loading, gross structural response, and local fatigue properties. Several techniques are shown to better study fatigue loads data. Common one-parameter models, such as the Rayleigh and exponential models are shown to produce dramatically different estimates of load distributions and fatigue damage. Improved fits may be achieved with the two-parameter Weibull model. High b values require better modeling of relatively large stress ranges; this is effectively done by matching at least two moments (Weibull) and better by matching still higher moments. For this purpose, a new, four-moment {open_quotes}generalized Weibull{close_quotes} model is introduced. Load and resistance factor design (LRFD) methodology for design against fatigue is proposed and demonstrated using data from two horizontal-axis wind turbines. To estimate fatigue damage, wind turbine blade loads have been represented by their first three statistical moments across a range of wind conditions. Based on the moments {mu}{sub 1}{hor_ellipsis}{mu}{sub 3}, new {open_quotes}quadratic Weibull{close_quotes} load distribution models are introduced. The fatigue reliability is found to be notably affected by the choice of load distribution model.

Lange, C.H. [Stanford Univ., CA (United States)

1996-05-01

94

On the biological plausibility of Wind Turbine Syndrome.  

PubMed

An emerging environmental health issue relates to potential ill-effects of wind turbine noise. There have been numerous suggestions that the low-frequency acoustic components in wind turbine signals can cause symptoms associated with vestibular system disorders, namely vertigo, nausea, and nystagmus. This constellation of symptoms has been labeled as Wind Turbine Syndrome, and has been identified in case studies of individuals living close to wind farms. This review discusses whether it is biologically plausible for the turbine noise to stimulate the vestibular parts of the inner ear and, by extension, cause Wind Turbine Syndrome. We consider the sound levels that can activate the semicircular canals or otolith end organs in normal subjects, as well as in those with preexisting conditions known to lower vestibular threshold to sound stimulation. PMID:25295915

Harrison, Robert V

2014-10-01

95

Advanced controls for floating wind turbines  

E-print Network

Floating Offshore Wind Turbines (FOWT) is a technology that stands to spearhead the rapid growth of the offshore wind energy sector and allow the exploration of vast high quality wind resources over coastal and offshore ...

Casanovas, Carlos (Casanovas Bermejo)

2014-01-01

96

A Dynamic Wind Turbine Simulator of the Wind Turbine Generator System  

Microsoft Academic Search

To study dynamic performances of wind turbine generator system (WTGS), and to determine the control structures in laboratory. The dynamic torque generated by wind turbine (WT) must be simulated. In there paper, a dynamic wind turbine emulator (WTE) is designed, which consider wind shear and tower shadow effect, and a dynamic torque compensation scheme is also developed to compensate the

Lei Lu; Zhen Xie; Xing Zhang; Shuying Yang; Renxian Cao

2012-01-01

97

Modern control design for flexible wind turbines  

Microsoft Academic Search

Control can improve energy capture and reduce dynamic loads in wind turbines. In the 1970s and 1980s wind turbines used classical control designs to regulate power and speed. The methods used, however, were not always successful. These systems often had bandwidths large enough to destabilize low-damped flexible modes leading to high dynamic load fatigue failures. Modern turbines are larger, mounted

Alan Duane Wright

2003-01-01

98

Chapter 14: Wind Turbine Control Systems  

SciTech Connect

Wind turbines are complex, nonlinear, dynamic systems forced by gravity, stochastic wind disturbances, and gravitational, centrifugal, and gyroscopic loads. The aerodynamic behavior of wind turbines is nonlinear, unsteady, and complex. Turbine rotors are subjected to a complicated three-dimensional turbulent wind inflow field that drives fatigue loading. Wind turbine modeling is also complex and challenging. Accurate models must contain many degrees of freedom (DOF) to capture the most important dynamic effects. The rotation of the rotor adds complexity to the dynamics modeling. Designs of control algorithms for wind turbines must account for these complexities. Algorithms must capture the most important turbine dynamics without being too complex and unwieldy. Off-the-shelf commercial soft ware is seldom adequate for wind turbine dynamics modeling. Instead, specialized dynamic simulation codes are usually required to model all the important nonlinear effects. As illustrated in Figure 14-1, a wind turbine control system consists of sensors, actuators and a system that ties these elements together. A hardware or software system processes input signals from the sensors and generates output signals for actuators. The main goal of the controller is to modify the operating states of the turbine to maintain safe turbine operation, maximize power, mitigate damaging fatigue loads, and detect fault conditions. A supervisory control system starts and stops the machine, yaws the turbine when there is a significant yaw misalignment, detects fault conditions, and performs emergency shut-downs. Other parts of the controller are intended to maximize power and reduce loads during normal turbine operation.

Wright, A. D.

2009-01-01

99

WindFloat: A floating foundation for offshore wind turbines  

Microsoft Academic Search

This manuscript summarizes the feasibility study conducted for the WindFloat technology. The WindFloat is a three-legged floating foundation for multimegawatt offshore wind turbines. It is designed to accommodate a wind turbine, 5 MW or larger, on one of the columns of the hull with minimal modifications to the nacelle and rotor. Potential redesign of the tower and of the turbine

Dominique Roddier; Christian Cermelli; Alexia Aubault; Alla Weinstein

2010-01-01

100

Wind turbine performance under icing conditions  

Microsoft Academic Search

The effects of rime ice on horizontal axis wind turbine performance were estimated. For typical supercooled fog conditions found in cold northern regions, four rime ice accretions on the S809 wind turbine airfoil were predicted using the NASA LEWICE code. The resulting airfoil\\/ice profile combinations were wind tunnel tested to obtain the lift, drag, and pitching moment characteristics over the

W. J. Jasinski; S. C. Noe; M. S. Selig; M. B. Bragg

1998-01-01

101

Small Wind Research Turbine: Final Report  

SciTech Connect

The Small Wind Research Turbine (SWRT) project was initiated to provide reliable test data for model validation of furling wind turbines and to help understand small wind turbine loads. This report will familiarize the user with the scope of the SWRT test and support the use of these data. In addition to describing all the testing details and results, the report presents an analysis of the test data and compares the SWRT test data to simulation results from the FAST aeroelastic simulation model.

Corbus, D.; Meadors, M.

2005-10-01

102

Wind Turbine Acoustic Noise A white paper  

E-print Network

Wind Turbine Acoustic Noise A white paper Prepared by the Renewable Energy Research Laboratory......................................................................................................................... 3 Noise and Sound Fundamentals.......................................................................................... 4 Sound and Noise

Massachusetts at Amherst, University of

103

Wind profiles for large wind turbines  

NASA Astrophysics Data System (ADS)

The 12MW project aimed to describe wind profiles and turbulence at levels high in the atmosphere where large wind turbines operate. During the project observations up to 180 m above sea level were collected using mast and lidar offshore in the North Sea at the Horns Rev wind farm in 2006. Later also land-based observations were collected at the coastal station Høvsøre at the North Sea coast of Jutland, Denmark. The most recent observations include wind profiles up to 300 m above ground. In addition, ceilometers observations were collected. Based on the observations results have been obtained and published. Some of the interesting findings are that the atmospheric planetary boundary layer (PBL) often is rather shallow, and as the logarithmic wind profile is only valid in the lower 10% of the PBL, other scaling parameters than roughness is needed. It has been shown that the height of the PBL is an important scaling parameter. Other results include variations in the wind profile as a function of stability, and in particular, for stable stratification the results deviate much from the simple profile equation. The observations and the new profile equations and the results will be presented. Part of the work in the 12MW project has been to compare mast observations to lidar observations, and the results are good indeed. This has given a basis to merge the observations into profiles using mast data at the lower levels and lidar data at the higher levels, thus extending the wind profiles up to high levels in the atmosphere.

Hasager, C. B.; Peña, A.; Gryning, S.-E.; Mikkelsen, T.; Courtney, M.

2009-04-01

104

Installation and initial operation of a 4100 watt wind turbine  

NASA Technical Reports Server (NTRS)

The results are presented of 211 days of operation of the 4.1 kilowatt wind turbine, which was the largest commercially available wind turbine. The wind turbine, electric controls and load bank, and the pivoted tower are described.

Tryon, H. B.; Richards, T.

1975-01-01

105

Investigation on installation of offshore wind turbines  

NASA Astrophysics Data System (ADS)

Wind power has made rapid progress and should gain significance as an energy resource, given growing interest in renewable energy and clean energy. Offshore wind energy resources have attracted significant attention, as, compared with land-based wind energy resources, offshore wind energy resources are more promising candidates for development. Sea winds are generally stronger and more reliable and with improvements in technology, the sea has become a hot spot for new designs and installation methods for wind turbines. In the present paper, based on experience building offshore wind farms, recommended foundation styles have been examined. Furthermore, wave effects have been investigated. The split installation and overall installation have been illustrated. Methods appropriate when installing a small number of turbines as well as those useful when installing large numbers of turbines were analyzed. This investigation of installation methods for wind turbines should provide practical technical guidance for their installation.

Wang, Wei; Bai, Yong

2010-06-01

106

Collected Papers on Wind Turbine Technology  

NASA Technical Reports Server (NTRS)

R and D projects on electricity generating wind turbines were conducted at the NASA Lewis Research Center from 1973 to 1988. Most projects were sponsored by the U.S. Department of Energy (DOE), a major element of its Federal Wind Energy Program. Another large wind turbine project was by the Bureau of Reclamation of the U.S. Department of Interior (DOI). From 1988 to 1995, NASA wind energy activities have been directed toward the transfer of technology to commercial and academic organizations. As part of these technology transfer activities, previously unpublished manuscripts have been assembled and presented here to share the wind turbine research results with the wind energy community. A variety of wind turbine technology topics are discussed: Wind and wake models; Airfoil properties; Structural analysis and testing; Control systems; Variable speed generators; and acoustic noise. Experimental and theoretical results are discussed.

Spera, David A. (editor)

1995-01-01

107

Diffuser Augmented Wind Turbine Analysis Code  

E-print Network

Wind Energy is becoming a significant source of energy throughout the world. This ever increasing field will potentially reach the limit of availability and practicality with the wind farm sites and size of the turbine ...

Carroll, Jonathan

2014-05-31

108

Noise measurements around the Nibe (Denmark) wind turbines and the Windane 31 wind turbine  

NASA Astrophysics Data System (ADS)

Noise around the two 640 kW wind turbines, and a 300 kW wind turbine at various distances and wind velocities was measured. The results are stated partly as the energy equivalent, A-weighted sound pressure level as a function of the wind velocity, partly as frequency analyses based on tape recordings of the A-weighted sound pressure level. A subjective evaluation of the noise emission from the wind turbines is given.

Kristensen, J.

109

Designing Drive Trains for the Next Generation of Wind Turbines (FloDesign Wind Turbine Corporation)  

Microsoft Academic Search

Today's wind turbines have nearly reached their maximum possible efficiency and are limited to sites with a narrow profile of wind patterns. The patent-pending Mixer Ejector Wind Turbine (MEWT) concept proposed by FloDesign promises to outperform existing wind turbines by a factor of three or more in a much wider range of wind resources. Olin College’s FloDesign SCOPE team was

Mateen Abdul; Kelcy Adamec; Gavin Boggs; Matthew Crawford; Kevin Sihlanick; Russell Torres

2009-01-01

110

Mixer-Ejector Wind Turbine: Breakthrough High Efficiency Shrouded Wind Turbine  

SciTech Connect

Broad Funding Opportunity Announcement Project: FloDesign Wind Turbine’s innovative wind turbine, inspired by the design of jet engines, could deliver 300% more power than existing wind turbines of the same rotor diameter by extracting more energy over a larger area. FloDesign Wind Turbine’s unique shrouded design expands the wind capture area, and the mixing vortex downstream allows more energy to flow through the rotor without stalling the turbine. The unique rotor and shrouded design also provide significant opportunity for mass production and simplified assembly, enabling mid-scale turbines (approximately 100 kW) to produce power at a cost that is comparable to larger-scale conventional turbines.

None

2010-02-22

111

Wind Turbine Generator System Power Performance Test Report for the ARE442 Wind Turbine  

SciTech Connect

This report summarizes the results of a power performance test that NREL conducted on the ARE 442 wind turbine. This test was conducted in accordance with the International Electrotechnical Commission's (IEC) standard, Wind Turbine Generator Systems Part 12: Power Performance Measurements of Electricity Producing Wind Turbines, IEC 61400-12-1 Ed.1.0, 2005-12. However, because the ARE 442 is a small turbine as defined by IEC, NREL also followed Annex H that applies to small wind turbines. In these summary results, wind speed is normalized to sea-level air density.

van Dam, J.; Jager, D.

2010-02-01

112

Microprocessor control of a wind turbine generator  

NASA Technical Reports Server (NTRS)

A microprocessor based system was used to control the unattended operation of a wind turbine generator. The turbine and its microcomputer system are fully described with special emphasis on the wide variety of tasks performed by the microprocessor for the safe and efficient operation of the turbine. The flexibility, cost and reliability of the microprocessor were major factors in its selection.

Gnecco, A. J.; Whitehead, G. T.

1978-01-01

113

Sustainable Energy Solutions Task 2.0: Wind Turbine Reliability and Maintainability Enhancement through System-wide Structure Health Monitoring and Modifications to Rotating Components  

SciTech Connect

EXECUTIVE SUMARRY An evaluation of nondestructive structural health monitoring methods was completed with over 132 documents, 37 specifically about wind turbines, summarized into a technology matrix. This matrix lists the technology, what can be monitored with this technology, and gives a short summary of the key aspects of the technology and its application. Passive and active acoustic emission equipment from Physical Acoustics Corp. and Acellent Technologies have been evaluated and selected for use in experimental state loading and fatigue tests of composite wind turbine blade materials. Acoustic Emission (AE) and Active Ultrasonic Testing (AUT), were applied to composite coupons with both simulated and actual damage. The results found that, while composites are more complicated in nature, compared to metallic structures, an artificial neural network analysis could still be used to determine damage. For the AE system, the failure mode could be determined (i.e. fiber breakage, delamination, etc.). The Acellent system has been evaluated to work well with composite materials. A test-rig for reliability testing of the rotating components was constructed. The research on the types of bearings used in the wind turbines indicated that in most of the designs, the main bearings utilized to support the shaft are cylindrical roller bearings. The accelerated degradation testing of a population of bearings was performed. Vibration and acoustic emission data was collected and analyzed in order to identify a representative degradation signal for each bearing to identify the initiation of the degradation process in the bearings. Afterwards, the RMS of the vibration signal from degradation initiation up to the end of the useful life of the bearing was selected to predict the remaining useful life of the bearing. This step included fitting Autoregressive Moving Average (ARMA) models to the degradation signals and approximating the probability distribution function (PDF) of remaining useful life based on the results of Monte-Carlo simulation of the ARMA models. This step was performed for different percentages of the degradation signal of each bearing. The accuracy of the proposed approach then was assessed by comparing the actual life of the bearing and the estimated life of the bearing from the developed models. The results were impressive and indicated that the accuracy of the models improved as more data was utilized in developing the ARMA models (we get closer to the end of the life of the bearing).

Janet M Twomey, PhD

2010-04-30

114

Ris-R-1111(EN) Ultimate Loading of Wind Turbines  

E-print Network

analysis as well as a wind turbine reliability study. In the wind climate analysis, the distribution partial safety factors for design of such components against this failure mode, structural reliability ISBN 87-550-2536-6 ISBN 87-550-2537-4 (Internet) ISSN 0106-2840 Information Service Department, Risø

115

Aerodynamic interference between two Darrieus wind turbines  

SciTech Connect

The effect of aerodynamic interference on the performance of two curved bladed Darrieus-type vertical axis wind turbines has been calculated using a vortex/lifting line aerodynamic model. The turbines have a tower-to-tower separation distance of 1.5 turbine diameters, with the line of turbine centers varying with respect to the ambient wind direction. The effects of freestream turbulence were neglected. For the cases examined, the calculations showed that the downwind turbine power decrement (1) was significant only when the line of turbine centers was coincident with the ambient wind direction, (2) increased with increasing tipspeed ratio, and (3) is due more to induced flow angularities downstream than to speed deficits near the downstream turbine.

Schatzle, P.R.; Klimas, P.C.; Spahr, H.R.

1981-04-01

116

Superconductivity for Large Scale Wind Turbines  

SciTech Connect

A conceptual design has been completed for a 10MW superconducting direct drive wind turbine generator employing low temperature superconductors for the field winding. Key technology building blocks from the GE Wind and GE Healthcare businesses have been transferred across to the design of this concept machine. Wherever possible, conventional technology and production techniques have been used in order to support the case for commercialization of such a machine. Appendices A and B provide further details of the layout of the machine and the complete specification table for the concept design. Phase 1 of the program has allowed us to understand the trade-offs between the various sub-systems of such a generator and its integration with a wind turbine. A Failure Modes and Effects Analysis (FMEA) and a Technology Readiness Level (TRL) analysis have been completed resulting in the identification of high risk components within the design. The design has been analyzed from a commercial and economic point of view and Cost of Energy (COE) calculations have been carried out with the potential to reduce COE by up to 18% when compared with a permanent magnet direct drive 5MW baseline machine, resulting in a potential COE of 0.075 $/kWh. Finally, a top-level commercialization plan has been proposed to enable this technology to be transitioned to full volume production. The main body of this report will present the design processes employed and the main findings and conclusions.

R. Fair; W. Stautner; M. Douglass; R. Rajput-Ghoshal; M. Moscinski; P. Riley; D. Wagner; J. Kim; S. Hou; F. Lopez; K. Haran; J. Bray; T. Laskaris; J. Rochford; R. Duckworth

2012-10-12

117

Aeroelastic stability of wind turbine blades  

NASA Technical Reports Server (NTRS)

The second degree nonlinear aeroelastic equations for a flexible, twisted, nonuniform wind turbine blade were developed using Hamilton's principle. The derivation of these equations has its basis in the geometric nonlinear theory of elasticity. These equations with periodic coefficients are suitable for determining the aeroelastic stability and response of large wind turbine blades. Methods for solving these equations are discussed.

Kaza, K. R. V.

1928-01-01

118

Vertical axis wind turbine development: Executive summary  

Microsoft Academic Search

Information is presented concerning (1) the numerical solution of the aerodynamics of cross-flow wind turbines; (2) boundary layer considerations for a vertical axis wind turbine (VAWT); (3) VAWT outdoor test model; (4) low solidity blade tests; (5) high solidity blade design; (6) cost analysis of the VAWT test model; (7) structural parametric analysis of VAWT blades; and (8) cost study

R. E. Walters; J. B. Fanucci; P. W. Hill; P. G. Migliore

1979-01-01

119

Design evolution of large wind turbine generators  

NASA Technical Reports Server (NTRS)

During the past five years, the goals of economy and reliability have led to a significant evolution in the basic design--both external and internal--of large wind turbine systems. To show the scope and nature of recent changes in wind turbine designs, development of three types are described: (1) system configuration developments; (2) computer code developments; and (3) blade technology developments.

Spera, D. A.

1979-01-01

120

Wind Turbine Certification and Type Certification IEC WT 01: IEC System for Conformity Testing and Certification of Wind Turbines, 2001-04  

Microsoft Academic Search

Certification of wind turbines or components is state-of-the-art and a must in most places around the world. Furthermore certification to harmonised requirements is an active support of export. Therefore it is important for manufacturers, banks and insurances of wind turbines and components to know the different certification processes as well as guidelines. The procedures to obtain Type and Project Certificates

Mike Woebbeking; Axel Andreä; Axel Dombrowski; Germanischer Lloyd

121

Coated superalloy gas turbine components  

Microsoft Academic Search

A gas turbine component is described consisting of a non-symmetrical body made of material selected from the group consisting of nickel-base superalloy, cobalt-base superalloy and iron-base superalloy and an alloy coating metallurgically bonded by an interdiffusion zone and providing the outer surface for the coated body. The composition of the coating consists essentially of (in weight percent) about 43% chromium;

Luthra

1987-01-01

122

Atmospheric and Wake Turbulence Impacts on Wind Turbine Fatigue Loadings  

SciTech Connect

Large-eddy simulations of atmospheric boundary layers under various stability and surface roughness conditions are performed to investigate the turbulence impact on wind turbines. In particular, the aeroelastic responses of the turbines are studied to characterize the fatigue loading of the turbulence present in the boundary layer and in the wake of the turbines. Two utility-scale 5-MW turbines that are separated by seven rotor diameters are placed in a 3 km by 3 km by 1 km domain. They are subjected to atmospheric turbulent boundary layer flow and data is collected on the structural response of the turbine components. The surface roughness was found to increase the fatigue loads while the atmospheric instability had a small influence. Furthermore, the downstream turbines yielded higher fatigue loads indicating that the turbulent wakes generated from the upstream turbines have significant impact.

Lee, S.; Churchfield, M.; Moriarty, P.; Jonkman, J.; Michalakes, J.

2012-01-01

123

1Design limits and solutions for very large wind turbines Design limits and solutions for very large wind turbines  

E-print Network

#12;#12;1Design limits and solutions for very large wind turbines UpWind Design limits Photo:Nordex #12;3Design limits and solutions for very large wind turbines Contents 1. UpWind: Summary and solutions for very large wind turbines A 20 MW turbine is feasible March 2011 Supported by: #12;March 20112

Leu, Tzong-Shyng "Jeremy"

124

Meteorological aspects of siting large wind turbines  

SciTech Connect

This report, which focuses on the meteorological aspects of siting large wind turbines (turbines with a rated output exceeding 100 kW), has four main goals. The first is to outline the elements of a siting strategy that will identify the most favorable wind energy sites in a region and that will provide sufficient wind data to make responsible economic evaluations of the site wind resource possible. The second is to critique and summarize siting techniques that were studied in the Department of Energy (DOE) Wind Energy Program. The third goal is to educate utility technical personnel, engineering consultants, and meteorological consultants (who may have not yet undertaken wind energy consulting) on meteorological phenomena relevant to wind turbine siting in order to enhance dialogues between these groups. The fourth goal is to minimize the chances of failure of early siting programs due to insufficient understanding of wind behavior.

Hiester, T.R.; Pennell, W.T.

1981-01-01

125

Wind Turbine Performance Under Icing Conditions  

Microsoft Academic Search

The effects of rime ice on horizontal axis wind turbine performance were estimated. For typical supercooled fog conditions found in cold northern regions, four rime ice accretions on the S809 wind turbine airfoil were predicted using the NASA LEWICE code. The resulting airfoil\\/ice profile combinations were wind-tunnel tested to obtain the lift, drag, and pitching moment characteristics over the Reynolds

William J. Jasinski; Urbana Shawn; C. Noe

1998-01-01

126

Wind turbine control system modeling capabilities  

SciTech Connect

At the National Renewable Energy Laboratory`s (NREL`s) National Wind Technology Center the authors are continuing to make progress in their ability to model complete wind turbine systems. An ADAMS{reg_sign} model of the NREL variable speed test bed turbine was developed to determine whether wind turbine control systems could be simulated and to investigate other control strategies for this turbine. Model simulations are compared with data from the operating turbine using the current mode of operation. In general, the simulations show good agreement with test data. Having established confidence in their ability to model the physical machine, the authors evaluated two other control methods. The methods studied are a generalized predictive control method and a bias estimation method. Simulation results using these methods are compared to simulation results of the current mode of operation of the turbine.

Pierce, K.; Fingersh, L.J.

1998-04-01

127

Numerical investigation of wind turbine and wind farm aerodynamics  

NASA Astrophysics Data System (ADS)

A numerical method based on the solution of Reynolds Averaged Navier Stokes equations and actuator disk representation of turbine rotor is developed and implemented in the OpenFOAM software suite for aerodynamic analysis of horizontal axis wind turbines (HAWT). The method and the implementation are validated against the 1-D momentum theory, the blade element momentum theory and against experimental data. The model is used for analyzing aerodynamics of a novel dual rotor wind turbine concept and wind farms. Horizontal axis wind turbines suffer from aerodynamic inefficiencies in the blade root region (near the hub) due to several non-aerodynamic constraints (e.g., manufacturing, transportation, cost, etc.). A new dual-rotor wind turbine (DRWT) concept is proposed that aims at mitigating these losses. A DRWT is designed using an existing turbine rotor for the main rotor (Risoe turbine and NREL 5 MW turbine), while the secondary rotor is designed using a high lift to drag ratio airfoil (the DU 96 airfoil from TU Delft). The numerical aerodynamic analysis method developed as a part of this thesis is used to optimize the design. The new DRWT design gives an improvement of about 7% in aerodynamic efficiency over the single rotor turbine. Wind turbines are typically deployed in clusters called wind farms. HAWTs also suffer from aerodynamic losses in a wind farm due to interactions with wind turbine wakes. An interesting mesoscale meteorological phenomenon called "surface flow convergence" believed to be caused by wind turbine arrays is investigated using the numerical method developed here. This phenomenon is believed to be caused by the pressure gradient set up by wind turbines operating in close proximity in a farm. A conceptual/hypothetical wind farm simulation validates the hypothesis that a pressure gradient is setup in wind farms due to turbines and that it can cause flow veering of the order of 10 degrees. Simulations of a real wind farm (Story County) are also conducted which give qualitatively correct flow direction change, however quantitative agreement with data is only moderately acceptable.

Selvaraj, Suganthi

128

Active load control techniques for wind turbines.  

SciTech Connect

This report provides an overview on the current state of wind turbine control and introduces a number of active techniques that could be potentially used for control of wind turbine blades. The focus is on research regarding active flow control (AFC) as it applies to wind turbine performance and loads. The techniques and concepts described here are often described as 'smart structures' or 'smart rotor control'. This field is rapidly growing and there are numerous concepts currently being investigated around the world; some concepts already are focused on the wind energy industry and others are intended for use in other fields, but have the potential for wind turbine control. An AFC system can be broken into three categories: controls and sensors, actuators and devices, and the flow phenomena. This report focuses on the research involved with the actuators and devices and the generated flow phenomena caused by each device.

van Dam, C.P. (University of California, Davis, CA); Berg, Dale E.; Johnson, Scott J. (University of California, Davis, CA)

2008-07-01

129

The 200-kilowatt wind turbine project  

NASA Technical Reports Server (NTRS)

The three 200 kilowatt wind turbines described, compose the first of three separate systems. Proposed wind turbines of the two other systems, although similar in design, are larger in both physical size and rated power generation. The overall objective of the project is to obtain early operation and performance data while gaining initial experience in the operation of large, horizontal-axis wind turbines in typical utility environments. Several of the key issues addressed include the following: (1) impact of the variable power output (due to varying wind speeds) on the utility grid (2) compatibility with utility requirements (voltage and frequency control of generated power) (3) demonstration of unattended, fail-safe operation (4) reliability of the wind turbine system (5) required maintenance and (6) initial public reaction and acceptance.

1978-01-01

130

Data Analytics Methods in Wind Turbine Design and Operations  

E-print Network

wind turbine. The extreme load is the highest stress level that the turbine structure would experience during its service lifetime. A wind turbine should be designed to resist such a high load to avoid catastrophic structural failures. To assess...

Lee, Giwhyun

2013-05-22

131

Effect of hub fairings on wind turbine rotor performance  

Microsoft Academic Search

Hub fairings or spinners are frequently suggested for wind turbines for reasons of aesthetics or performance. While hub fairings rarely, if ever, decrease the appearance of a wind turbine, the effects of a nose fairing may actually decrease rather than increase wind turbine rotor performance. Analysis of hub fairings effects on wind turbine performance is presented.

1978-01-01

132

Horizontal axis wind turbine systems: optimization using genetic algorithms  

NASA Astrophysics Data System (ADS)

A method for the optimization of a grid-connected wind turbine system is presented. The behaviour of the system components is coupled in a non-linear way, and optimization must take into account technical and economical aspects of the complete system design. The annual electrical energy cost is estimated using a cost model for the wind turbine rotor, nacelle and tower and an energy output model based on the performance envelopes of the power coefficient of the rotor, CP, on the Weibull parameters k and c and on the power law coefficient of the wind profile. In this study the site is defined with these three parameters and the extreme wind speed Vmax. The model parameters vary within a range of possible values. Other elements of the project (foundation, grid connection, financing cost, etc.) are taken into account through coefficients. The optimal values of the parameters are determined using genetic algorithms, which appear to be efficient for such a problem. These optimal values were found to be very different for a Mediterranean site and a northern European site using our numerical model. Optimal wind turbines at the Mediterranean sites considered in this article have an excellent profitability compared with reference northern European wind turbines. Most of the existing wind turbines appear to be well designed for northern European sites but not for Mediterranean sites.

Diveux, T.; Sebastian, P.; Bernard, D.; Puiggali, J. R.; Grandidier, J. Y.

2001-10-01

133

Measurements on a wind turbine wake: 3D effects and bluff body vortex shedding  

Microsoft Academic Search

The velocity field in the wake of a two-bladed wind turbine model (diameter 180 mm) has been studied under different conditions using a two-component hot wire. All three velocity components were measured both for the turbine rotor normal to the oncoming flow as well as with the turbine inclined to the freestream direction (the yaw angle was varied from 0°

D. Medici; P. H. Alfredsson

2006-01-01

134

Improving Wind Turbine Efficiency with Plasma Actuators  

NASA Astrophysics Data System (ADS)

As increasing the efficiency of modern wind turbines becomes more difficult, the use of active flow control now represents a more attractive means of possible improvement. This ongoing study examines utilizing single dielectric barrier discharge (SDBD) plasma actuators on wind turbine rotors to increase power generation. Blade element momentum (BEM) theory is used to identify regimes with the greatest potential for improvement and to estimate possible gains. Wind tunnel tests are conducted with plasma actuators to determine the amount of aerodynamic control achievable. In addition, the scope of a new "Laboratory for Enhanced Wind Energy Design" is outlined. Most critically, this resource includes two full-scale wind turbines to balance the known limitations of existing theory and wind tunnel testing by providing the capability to test novel blade designs and control strategies in the field.

Cooney, John; Corke, Thomas; Nelson, Robert

2010-11-01

135

The new Wind Technology Test Center is the only facility in the nation capable of testing wind turbine blades up to  

E-print Network

turbine blades up to 90 meters in length. A critical factor to wind turbine design and development is the ability to test new designs, components, and materials. In addition, wind turbine blade manufacturers Energy Center (MassCEC) to design, construct, and operate the Wind Technology Center (WTTC) in Boston

136

LES investigation of infinite staggered wind-turbine arrays  

NASA Astrophysics Data System (ADS)

The layouts of turbines affect the turbine wake interactions and thus the wind farm performance. The wake interactions in infinite staggered wind-turbine arrays are investigated and compared with infinite aligned turbine arrays in this paper. From the numerical results we identify three types of wake behaviours, which are significantly different from wakes in aligned wind-turbine arrays. For the first type, each turbine wake interferes with the pair of staggered downstream turbine wakes and the aligned downstream turbine. For the second type, each turbine wake interacts with the first two downstream turbine wakes but does not show significant interference with the second aligned downstream turbine. For the third type, each turbine wake recovers immediately after passing through the gap of the first two downstream turbines and has little interaction with the second downstream turbine wakes The extracted power density and power efficiency are also studied and compared with aligned wind-turbine arrays.

Yang, Xiaolei; Sotiropoulos, Fotis

2014-12-01

137

Structural analysis considerations for wind turbine blades  

NASA Technical Reports Server (NTRS)

Approaches to the structural analysis of wind turbine blade designs are reviewed. Specifications and materials data are discussed along with the analysis of vibrations, loads, stresses, and failure modes.

Spera, D. A.

1979-01-01

138

Wind Turbine Drivetrain Condition Monitoring - An Overview  

SciTech Connect

This paper provides an overview of wind turbine drivetrain condition monitoring based on presentations from a condition monitoring workshop organized by the National Renewable Energy Laboratory in 2009 and on additional references.

Sheng, S; Veers, P.

2011-10-01

139

Diffuser for augmenting a wind turbine  

DOEpatents

A diffuser for augmenting a wind turbine having means for energizing the boundary layer at several locations along the diffuser walls is improved by the addition of a short collar extending radially outward from the outlet of the diffuser.

Foreman, Kenneth M. (North Bellmore, NY); Gilbert, Barry L. (Westbury, NY)

1984-01-01

140

Microprocessor based control for wind turbines  

SciTech Connect

This paper will discuss the design of a microprocessor based control system for a Vertical Axis Wind Turbine (VAWT). A control philosophy is developed and the reasons for a microprocessor control are discussed. 5 refs.

Absi, M.; Dodd, C.

1980-01-01

141

Vertical Axis Wind Turbine Foundation parameter study  

SciTech Connect

The dynamic failure criterion governing the dimensions of prototype Vertical Axis Wind Turbine Foundations is treated as a variable parameter. The resulting change in foundation dimensions and costs is examined.

Lodde, P.F.

1980-07-01

142

Advanced control strategies for wind turbines  

NASA Astrophysics Data System (ADS)

As wind turbines become more complex and begin to incorporate variable speed operation, control algorithms that enable the wind turbine to operate as efficiently as possible will become more complicated. Also, most current control strategies do not take into account factors such as wake effects from upstream turbines and the fact that different turbine sites can have significantly different wind regimes. To aid a windfarm operator in developing appropriate control strategies, a computer code entitled ASYM has been developed at Sandia National Laboratories. ASYM is a wind turbine simulation program that can be used to evaluate different control strategies. This paper briefly describes ASYM and presents results from the code when used for evaluating control options for both variable-speed and constant-speed control. The code synthesizes dynamic wind speeds on a second-by-second basis in the time domain that conforms to a predetermined spectral content governed by the surface roughness length scale and the hourly average wind speed. The simulated wind speeds then drive a series of wind turbine (WT) control algorithms that predict key WT operational parameters such as number of annual starts and stops, annual energy production, and annual fatigue damage at a critically stressed joint on the WT. This paper also discusses future plans to improve and validate ASYM and to incorporate a comprehensive economics model and advanced control strategies such as fuzzy control, adaptive control, and expert systems. It has been shown that processes using fuzzy control algorithms operate more smoothly and more efficiently than processes that are controlled using classical methods. Fuzzy control is briefly explained and an example of its application to a wind turbine is given. The future plans include a continuing involvement with active wind plant operators who can provide feedback regarding the usefulness of the analytical tool and the validity of findings.

Schluter, L. L.; Vachon, William A.

143

Wind turbine rotor speed control system  

Microsoft Academic Search

A wind turbine rotor speed control for ensuring a constant rotational speed within tight tolerances includes a self-sufficient rotor incorporating aerodynamic and mechanical devices to provide the control. There is a fixed turbine blade adapted to be mounted on a shaft for rotation therewith, the fixed blade having pivotal blade tips at its respective ends. The pitch control of the

Kisovec

1982-01-01

144

Modeling of battery charging wind turbines  

Microsoft Academic Search

Small scale wind turbines are typically used in battery charging systems in off-grid and remote applications to provide electric power to small load locations such as homes, cabins and instrumentation stations. This paper is devoted to presenting the results from the modeling case-study of such a turbine. Analytical models, computer simulations and experimental results are presented.

Justin Reed; Giri Venkataramanan; Jonathan Rose

2007-01-01

145

The Design of Automatic Control System for Wind Turbine  

Microsoft Academic Search

According to the special form and structure of concentrated wind energy turbine, and based on the idea of largely use of wind energy, the author designed an automatic control system, which can control the wind facing of wind turbine and change bladepsilas pitch angle. Under the control this system, the concentrated wind energy turbine can not only meet the demand

Weixuan Li; Daoyong Sun

2009-01-01

146

Modelling of a chaotic load of wind turbines drivetrain  

NASA Astrophysics Data System (ADS)

The purpose of this paper is to present a model of the load of the wind turbine gears for simulation of real, varying operational conditions for modelling of wind turbine vibration. The characteristics of the wind, which generates chaotically varying loads on the drivetrain components generating load in teeth and bearings of gears during torque transfer, are discussed. A generator of variable load of wind turbines drivetrain is proposed. Firstly, the module for generation of wind speed is designed. It is based on the approach in which the wind speed was considered as a time series approximated by the Weierstrass function. Secondly, the rotational speed of the main shaft is proposed as a function of the wind speed value. The function depends on a few parameters that are fitted by using a genetic algorithm. Finally, the model of torque of the main shaft is introduced. This model has been created by using a multi-layer artificial neural network. The results show that the proposed approach yields a very good fit for the experimental data. The fit brings about the proper reproducing of all the aspects of the load that are crucial for causing fatigue and, as a consequence, damaging of gears of the wind turbines.

Bielecki, Andrzej; Barszcz, Tomasz; Wójcik, Mateusz

2015-03-01

147

Investigation of Wind Turbine Rotor Concepts for Offshore Wind Farms  

NASA Astrophysics Data System (ADS)

Current plans in offshore wind energy developments call for further reduction of cost of energy. In order to contribute to this goal, several wind turbine rotor concepts have been investigated. Assuming the future offshore wind turbines will operate only in the offshore wind farms, the rotor concepts are not only evaluated for their stand-alone performances and their potential in reducing the loads, but also for their performance in an offshore wind farm. In order to do that, the 10MW reference wind turbine designed in Innwind.EU project is chosen as baseline. Several rotor parameters have been modified and their influences are investigated for offshore wind turbine design purposes. This investigation is carried out as a conceptual parametrical study. All concepts are evaluated numerically with BOT (Blade optimisation tool) software in wind turbine level and with Farmflow software in wind farm level for two wind farm layouts. At the end, all these concepts are compared with each other in terms of their advantages and disadvantages.

Ceyhan, Özlem; Grasso, Francesco

2014-06-01

148

Wind Turbine Safety and Function Test Report for the Mariah Windspire Wind Turbine  

SciTech Connect

This test was conducted as part of the U.S. Department of Energy's (DOE) Independent Testing project. This project was established to help reduce the barriers to wind energy expansion by providing independent testing results for small wind turbines (SWT). In total, five turbines were tested at the National Wind Technology Center (NWTC) as a part of this project. Safety and function testing is one of up to five tests performed on the turbines, including power performance, duration, noise, and power-quality tests. NWTC testing results provide manufacturers with reports that may be used to meet part of small wind turbine certification requirements. The test equipment includes a Mariah Windspire wind turbine mounted on a monopole tower. L&E Machine manufactured the turbine in the United States. The inverter was manufactured separately by Technology Driven Products in the United States. The system was installed by the NWTC site operations group with guidance and assistance from Mariah Power.

Huskey, A.; Bowen, A.; Jager, D.

2010-07-01

149

Passively cooled direct drive wind turbine  

DOEpatents

A wind turbine is provided that passively cools an electrical generator. The wind turbine includes a plurality of fins arranged peripherally around a generator house. Each of the fins being oriented at an angle greater than zero degrees to allow parallel flow of air over the fin. The fin is further tapered to allow a constant portion of the fin to extend beyond the air stream boundary layer. Turbulence initiators on the nose cone further enhance heat transfer at the fins.

Costin, Daniel P. (Chelsea, VT)

2008-03-18

150

Coupled Dynamic Modeling of Floating Wind Turbine Systems: Preprint  

SciTech Connect

This article presents a collaborative research program that the Massachusetts Institute of Technology (MIT) and the National Renewable Energy Laboratory (NREL) have undertaken to develop innovative and cost-effective floating and mooring systems for offshore wind turbines in water depths of 10-200 m. Methods for the coupled structural, hydrodynamic, and aerodynamic analysis of floating wind turbine systems are presented in the frequency domain. This analysis was conducted by coupling the aerodynamics and structural dynamics code FAST [4] developed at NREL with the wave load and response simulation code WAMIT (Wave Analysis at MIT) [15] developed at MIT. Analysis tools were developed to consider coupled interactions between the wind turbine and the floating system. These include the gyroscopic loads of the wind turbine rotor on the tower and floater, the aerodynamic damping introduced by the wind turbine rotor, the hydrodynamic damping introduced by wave-body interactions, and the hydrodynamic forces caused by wave excitation. Analyses were conducted for two floater concepts coupled with the NREL 5-MW Offshore Baseline wind turbine in water depths of 10-200 m: the MIT/NREL Shallow Drafted Barge (SDB) and the MIT/NREL Tension Leg Platform (TLP). These concepts were chosen to represent two different methods of achieving stability to identify differences in performance and cost of the different stability methods. The static and dynamic analyses of these structures evaluate the systems' responses to wave excitation at a range of frequencies, the systems' natural frequencies, and the standard deviations of the systems' motions in each degree of freedom in various wind and wave environments. This article in various wind and wave environments. This article explores the effects of coupling the wind turbine with the floating platform, the effects of water depth, and the effects of wind speed on the systems' performance. An economic feasibility analysis of the two concepts was also performed. Key cost components included the material and construction costs of the buoy; material and installation costs of the tethers, mooring lines, and anchor technologies; costs of transporting and installing the system at the chosen site; and the cost of mounting the wind turbine to the platform. The two systems were evaluated based on their static and dynamic performance and the total system installed cost. Both systems demonstrated acceptable motions, and have estimated costs of $1.4-$1.8 million, not including the cost of the wind turbine, the power electronics, or the electrical transmission.

Wayman, E. N.; Sclavounos, P. D.; Butterfield, S.; Jonkman, J.; Musial, W.

2006-03-01

151

Wind Turbine Safety and Function Test Report for the Gaia-Wind 11-kW Wind Turbine  

SciTech Connect

This test was conducted as part of the U.S. Department of Energy's (DOE) Independent Testing project. This project was established to help reduce the barriers to wind energy expansion by providing independent testing results for small wind turbines (SWT). In total, four turbines were tested at the National Wind Technology Center (NWTC) as a part of this project. Safety and function testing is one of up to five tests performed on the turbines, including power performance, duration, noise, and power-quality tests. The results of the testing provide the manufacturers with reports that can be used for small wind turbine certification. The test equipment includes a Gaia-Wind 11-kW wind turbine mounted on an 18-m monopole tower. Gaia-Wind Ltd. manufactured the turbine in Denmark. The system was installed by the NWTC site operations group with guidance and assistance from Gaia-Wind.

Huskey, A.; Bowen, A.; Jager, D.

2010-01-01

152

Preliminary wind tunnel tests on the pedal wind turbine  

NASA Astrophysics Data System (ADS)

High solidity-low speed wind turbines are relatively simple to construct and can be used advantageously in many developing countries for such direct applications as water pumping. Established designs in this class, such as the Savonius and the American multiblade rotors, have the disadvantage that their moving surfaces require a rigid construction, thereby rendering large units uneconomical. In this respect, the pedal wind turbine recently reported by the author and which incorporates sail type rotors offers a number of advantages. This note reports preliminary results from a series of wind tunnel tests which were carried out to assess the aerodynamic torque and power characteristics of the turbine.

Vinayagalingam, T.

1980-06-01

153

Wind direction change criteria for wind turbine design  

Microsoft Academic Search

A method is presented for estimating the root mean square (rms) value of the wind direction change, Delta Theta (tau) = theta (tau + tau) - Theta (tau), that occurs over the swept area of wind turbine rotor systems. An equation is also given for the rms value of the wind direction change that occurs at a single point in

W. C. Cliff

1979-01-01

154

Behavior of bats at wind turbines  

PubMed Central

Wind turbines are causing unprecedented numbers of bat fatalities. Many fatalities involve tree-roosting bats, but reasons for this higher susceptibility remain unknown. To better understand behaviors associated with risk, we monitored bats at three experimentally manipulated wind turbines in Indiana, United States, from July 29 to October 1, 2012, using thermal cameras and other methods. We observed bats on 993 occasions and saw many behaviors, including close approaches, flight loops and dives, hovering, and chases. Most bats altered course toward turbines during observation. Based on these new observations, we tested the hypotheses that wind speed and blade rotation speed influenced the way that bats interacted with turbines. We found that bats were detected more frequently at lower wind speeds and typically approached turbines on the leeward (downwind) side. The proportion of leeward approaches increased with wind speed when blades were prevented from turning, yet decreased when blades could turn. Bats were observed more frequently at turbines on moonlit nights. Taken together, these observations suggest that bats may orient toward turbines by sensing air currents and using vision, and that air turbulence caused by fast-moving blades creates conditions that are less attractive to bats passing in close proximity. Tree bats may respond to streams of air flowing downwind from trees at night while searching for roosts, conspecifics, and nocturnal insect prey that could accumulate in such flows. Fatalities of tree bats at turbines may be the consequence of behaviors that evolved to provide selective advantages when elicited by tall trees, but are now maladaptive when elicited by wind turbines. PMID:25267628

Cryan, Paul. M.; Gorresen, P. Marcos; Hein, Cris D.; Schirmacher, Michael R.; Diehl, Robert H.; Huso, Manuela M.; Hayman, David T. S.; Fricker, Paul D.; Bonaccorso, Frank J.; Johnson, Douglas H.; Heist, Kevin; Dalton, David C.

2014-01-01

155

Behavior of bats at wind turbines  

USGS Publications Warehouse

Wind turbines are causing unprecedented numbers of bat fatalities. Many fatalities involve tree-roosting bats, but reasons for this higher susceptibility remain unknown. To better understand behaviors associated with risk, we monitored bats at three experimentally manipulated wind turbines in Indiana, United States, from July 29 to October 1, 2012, using thermal cameras and other methods. We observed bats on 993 occasions and saw many behaviors, including close approaches, flight loops and dives, hovering, and chases. Most bats altered course toward turbines during observation. Based on these new observations, we tested the hypotheses that wind speed and blade rotation speed influenced the way that bats interacted with turbines. We found that bats were detected more frequently at lower wind speeds and typically approached turbines on the leeward (downwind) side. The proportion of leeward approaches increased with wind speed when blades were prevented from turning, yet decreased when blades could turn. Bats were observed more frequently at turbines on moonlit nights. Taken together, these observations suggest that bats may orient toward turbines by sensing air currents and using vision, and that air turbulence caused by fast-moving blades creates conditions that are less attractive to bats passing in close proximity. Tree bats may respond to streams of air flowing downwind from trees at night while searching for roosts, conspecifics, and nocturnal insect prey that could accumulate in such flows. Fatalities of tree bats at turbines may be the consequence of behaviors that evolved to provide selective advantages when elicited by tall trees, but are now maladaptive when elicited by wind turbines.

Cryan, Paul; Gorresen, Marcos; Hine, Cris D.; Schirmacher, Michael; Diehl, Robert H.; Huso, Manuela M.; Hayman, David T.S.; Fricker, Paul D.; Bonaccorso, Frank J.; Johnson, Douglas H.; Heist, Kevin; Dalton, David C.

2014-01-01

156

Tribological advancements for reliable wind turbine performance.  

PubMed

Wind turbines have had various limitations to their mechanical system reliability owing to tribological problems over the past few decades. While several studies show that turbines are becoming more reliable, it is still not at an overall acceptable level to the operators based on their current business models. Data show that the electrical components are the most problematic; however, the parts are small, thus easy and inexpensive to replace in the nacelle, on top of the tower. It is the tribological issues that receive the most attention as they have higher costs associated with repair or replacement. These include the blade pitch systems, nacelle yaw systems, main shaft bearings, gearboxes and generator bearings, which are the focus of this review paper. The major tribological issues in wind turbines and the technological developments to understand and solve them are discussed within. The study starts with an overview of fretting corrosion, rolling contact fatigue, and frictional torque of the blade pitch and nacelle yaw bearings, and references to some of the recent design approaches applied to solve them. Also included is a brief overview into lubricant contamination issues in the gearbox and electric current discharge or arcing damage of the generator bearings. The primary focus of this review is the detailed examination of main shaft spherical roller bearing micropitting and gearbox bearing scuffing, micropitting and the newer phenomenon of white-etch area flaking. The main shaft and gearbox are integrally related and are the most commonly referred to items involving expensive repair costs and downtime. As such, the latest research and developments related to the cause of the wear and damage modes and the technologies used or proposed to solve them are presented. PMID:20855322

Kotzalas, Michael N; Doll, Gary L

2010-10-28

157

Modified Adaptive Control for Region 3 Operation in the Presence of Wind Turbine Structural Modes  

NASA Technical Reports Server (NTRS)

Many challenges exist for the operation of wind turbines in an efficient manner that is reliable and avoids component fatigue and failure. Turbines operate in highly turbulent environments resulting in aerodynamic loads that can easily excite turbine structural modes, possibly causing component fatigue and failure. Wind turbine manufacturers are highly motivated to reduce component fatigue and failure that can lead to loss of revenue due to turbine down time and maintenance costs. The trend in wind turbine design is toward larger, more flexible turbines that are ideally suited to adaptive control methods due to the complexity and expense required to create accurate models of their dynamic characteristics. In this paper, we design an adaptive collective pitch controller for a high-fidelity simulation of a utility-scale, variable-speed horizontal axis wind turbine operating in Region 3. The objective of the adaptive pitch controller is to regulate generator speed, accommodate wind gusts, and reduce the excitation of structural modes in the wind turbine. The control objective is accomplished by collectively pitching the turbine blades. The adaptive collective pitch controller for Region 3 was compared in simulations with a baseline classical Proportional Integrator (PI) collective pitch controller. The adaptive controller will demonstrate the ability to regulate generator speed in Region 3, while accommodating gusts, and reducing the excitation of certain structural modes in the wind turbine.

Frost, Susan Alane; Balas, Mark J.; Wright, Alan D.

2010-01-01

158

Analysis of Counter-Rotating Wind Turbines  

NASA Astrophysics Data System (ADS)

This paper presents a study on the performance of a wind turbine with two counter-rotating (CRWT) rotors. The characteristics of the two counter-rotating rotors are on a 3-bladed Nordtank 500 kW rotor. The analysis has been carried out by using an Actuator Line technique implemented in the Navier-Stokes code EllipSys3D. The analysis shows that the Annual Energy Production can be increased to about 43.5 %, as compared to a wind turbine with a single rotor. In order to determine the optimal settings of the CRWT turbine, parameters such as distance between two rotors and rotational speed have been studied.

Shen, W. Z.; Zakkam, V. A. K.; Sørensen, J. N.; Appa, K.

2007-07-01

159

Vertical axis wind turbine designed aerodynamically at Tokai University  

Microsoft Academic Search

The advantages of the vertical axis wind turbine over conventional propeller-type wind turbines are listed, among them the fact that the turbine is free from the gyroscopic loading accompanied by wind direction tracking. Special attention is given to the straight-wing type vertical axis turbine, which is thought to be particularly advantageous. Also discussed are the characteristics of the blade. It

Y. Kato; K. Seki; Y. Shimizu

1981-01-01

160

Low frequency noise from MW wind turbines --mechanisms of generation  

E-print Network

Low frequency noise from MW wind turbines -- mechanisms of generation and its modeling Helge MW wind turbines -- mechanisms of generation and its modeling Department: Department of Wind Energy on this turbine a number of important turbine design parameters with influence on the LFN have been identified

161

Nation's tallest VAWT (Vertical Axis Wind Turbine) turning out the watts. [Vertical Axis Wind Turbine  

Microsoft Academic Search

This article describes the development of the tallest and most powerful windmill of its kind in the U.S. Known as a Vertical Axis Wind Turbine (VAWT), the machine is meant for testing new concepts in vertical axis turbine design. As part of its overall testing program, the turbine will supply electricity to automated water pumps used in irrigation research at

1988-01-01

162

Jet spoiler arrangement for wind turbine  

DOEpatents

An air jet spoiler arrangement is provided for a Darrieus-type vertical axis wind-powered turbine. Air is drawn into hollow turbine blades through air inlets at the ends thereof and is ejected in the form of air jets through small holes or openings provided along the lengths of the blades. The air jets create flow separation at the surfaces of the turbine blades, thereby inducing stall conditions and reducing the output power. A feedback control unit senses the power output of the turbine and controls the amount of air drawn into the air inlets accordingly.

Cyrus, Jack D. (Corrales, NM); Kadlec, Emil G. (Albuquerque, NM); Klimas, Paul C. (Albuquerque, NM)

1985-01-01

163

Jet spoiler arrangement for wind turbine  

DOEpatents

An air jet spoiler arrangement is provided for a Darrieus-type vertical axis wind-powered turbine. Air is drawn into hollow turbine blades through air inlets at the end thereof and is ejected in the form of air jets through small holes or openings provided along the lengths of the blades. The air jets create flow separation at the surfaces of the turbine blades, thereby including stall conditions and reducing the output power. A feedback control unit senses the power output of the turbine and controls the amount of air drawn into the air inlets accordingly.

Cyrus, J.D.; Kadlec, E.G.; Klimas, P.C.

1983-09-15

164

Infrasound emission generated by wind turbines  

NASA Astrophysics Data System (ADS)

Aerodynamic noise emissions from the continuously growing number of wind turbines in Germany are creating increasing problems for infrasound recording systems. Such systems are equipped with highly sensitive micro pressure sensors, which are accurately measuring acoustic signals in a frequency range inaudible to humans. At infrasound station IGADE, north of Bremen, a constantly increasing background noise has been observed throughout the years since its installation in 2005. The spectral peaks are reflecting well the blade passing harmonics, which vary with prevailing wind speeds. Overall, a decrease is noted for the infrasound array's detection capability. This aspect is particularly important for the other two sites of the German infrasound stations I26DE in the Bavarian Forest and I27DE in Antarctica, because plans for installing wind turbines near these locations are being under discussion. These stations are part of the International Monitoring System (IMS) verifying compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT), and have to meet stringent specifications with respect to infrasonic background noise. Therefore data obtained during a field experiment with mobile micro-barometer stations for measuring the infrasonic pressure level of a single horizontal-axis wind turbine have been revisited. The results of this experiment successfully validate a theoretical model which estimates the generated sound pressure level of wind turbines and makes it possible to specify the minimum allowable distance between wind turbines and infrasound stations for undisturbed recording. Since the theoretical model also takes wind turbine design parameters into account, suitable locations for planned infrasound stations outside the determined disturbance range can be found, which will be presented; and vice versa, the model calculations' results for fixing the minimum distance for wind turbines planned for installation in the vicinity of an existing infrasound array.

Ceranna, Lars; Pilger, Christoph

2014-05-01

165

Tutorial of Wind Turbine Control for Supporting Grid Frequency through Active Power Control: Preprint  

SciTech Connect

As wind energy becomes a larger portion of the world's energy portfolio and wind turbines become larger and more expensive, wind turbine control systems play an ever more prominent role in the design and deployment of wind turbines. The goals of traditional wind turbine control systems are maximizing energy production while protecting the wind turbine components. As more wind generation is installed there is an increasing interest in wind turbines actively controlling their power output in order to meet power setpoints and to participate in frequency regulation for the utility grid. This capability will be beneficial for grid operators, as it seems possible that wind turbines can be more effective at providing some of these services than traditional power plants. Furthermore, establishing an ancillary market for such regulation can be beneficial for wind plant owner/operators and manufacturers that provide such services. In this tutorial paper we provide an overview of basic wind turbine control systems and highlight recent industry trends and research in wind turbine control systems for grid integration and frequency stability.

Aho, J.; Buckspan, A.; Laks, J.; Fleming, P.; Jeong, Y.; Dunne, F.; Churchfield, M.; Pao, L.; Johnson, K.

2012-03-01

166

Vertical axis wind turbine control strategy  

SciTech Connect

Early expensive in automatic operation of the Sandia 17-m vertical axis research wind turbine (VAWT) has demonstrated the need for a systematic study of control algorithms. To this end, a computer model has been developed that uses actual wind time series and turbine performance data to calculate the power produced by the Sandia 17-m VAWT operating in automatic control. The model has been used to investigate the influence of starting algorithms on annual energy production. The results indicate that, depending on turbine and local wind characteristics, a bad choice of a control algorithm can significantly reduce overall energy production. The model can be used to select control algorithms and threshold parameters that maximize long-term energy production. An attempt has been made to generalize these results from local site and turbine characteristics to obtain general guidelines for control algorithm design.

McNerney, G.M.

1981-08-01

167

Investigation of Various Wind Turbine Drivetrain Condition Monitoring Techniques  

SciTech Connect

The wind industry has experienced premature turbine component failures during the past years. With the increase in turbine size, these failures, especially those found in the major drivetrain components, i.e. main shaft, gearbox, and generator, have become extremely costly. Given that the gearbox is the most costly component in the drivetrain to fix, the National Renewable Energy Laboratory (NREL) initiated the Gearbox Reliability Collaborative (GRC) to determine the causes for premature gearbox failures and subsequently, recommend improvements to gearbox design, manufacture, and operational practices. The GRC has two identical test gearboxes, which are planned for a dynamometer and a field test, respectively.

Sheng, S.; Oyague, F.; Butterfield, S.

2010-08-01

168

CFD Simulations on Interference Effects between Offshore Wind Turbines  

NASA Astrophysics Data System (ADS)

This paper presents results of detailed 3D CFD simulations of two 5MW wind turbines sited in the German wind farm Alpha Ventus which are located behind each other at half-wake conditions. The focus of interest in this study is put on wake - turbine interaction, in order to derive the main shadow effects and their influence on blade loads and power response of the downstream turbine. For this purpose, Detached Eddy Simulations (DES) were performed using the flow solver FLOWer from DLR (German Aerospace Center). To consider all relevant aerodynamic effects, the main turbine components are represented as direct model with resolved boundary layers. Measurement-based turbulent inflow conditions are prescribed to realistically account for the atmospheric boundary layer. In order to analyze the flow conditions in front of the downstream turbine, wake propagation and velocity spectra are evaluated and compared with the undisturbed atmospheric boundary layer. Their impact on loads and power production and their corresponding fluctuations is discussed by comparing these with the upstream turbine. It was found, that fatigue loads occurring at half-wake conditions are significantly higher for the downstream turbine, since blade load fluctuations are highly amplified by the unsteady wake of the upstream turbine.

Weihing, P.; Meister, K.; Schulz, C.; Lutz, Th; Krämer, E.

2014-06-01

169

On the power regulation of small wind turbines based on experience with small Danish wind turbines  

Microsoft Academic Search

The state of development of the small wind turbines on the Danish market covering a range of 10 to 55 kW, of which approximately 500 are in operation is discussed. A typical feature of Danish small wind turbines is the regulation of the power output by stalling of the rotor blades. The merits of the stall regulation are discussed with

P. Lundsager

1981-01-01

170

Innovative wind turbines. Circulation controlled vertical axis wind turbine. Progress report, March 1December 31, 1976  

Microsoft Academic Search

Theoretical and experimental research efforts in evaluating an innovative concept for vertical axis wind turbines (VAWT) are described. The concept is that of using straight blades composed of circulation controlled airfoil sections. The theoretical analysis has been developed to determine the unsteady lift and moment characteristics of multiple-blade cross-flow wind turbines. To determine the drag data needed as input to

R. E. Walters; J. B. Fanucci; P. W. Hill; P. G. Migliore; W. Squire; T. L. Waltz

1978-01-01

171

Load attenuating passively adaptive wind turbine blade  

Microsoft Academic Search

A method and apparatus for improving wind turbine performance by alleviating loads and controlling the rotor. The invention employs the use of a passively adaptive blade that senses the wind velocity or rotational speed, and accordingly modifies its aerodynamic configuration. The invention exploits the load mitigation prospects of a blade that twists toward feather as it bends. The invention includes

Paul S. Veers; Donald W. Lobitz

2003-01-01

172

Multilevel converters for 10 MW Wind Turbines  

Microsoft Academic Search

Several promising multi-level converter configurations for 10 MW Wind Turbines both with direct drive and one-stage gear box drive using Permanent Magnet Synchronous Generator (PMSG) are proposed, designed and compared. Reliability is a crucial indicator for large scale wind power converters, therefore the evaluations are mainly focused on the power device thermal performances, which are closely related to the life

Ke Ma; Frede Blaabjerg

2011-01-01

173

Torque ripple in a Darrieus, vertical axis wind turbine  

SciTech Connect

Interaction between a steady wind and a rotating, Darrieus, vertical axis wind turbine produces time periodic aerodynamic loads which cause time dependent torque variations, referred to as torque ripple, to occur in the mechanical link between the turbine and the electrical generator. There is concern for the effect of torque ripple upon fatigue life of drive train components and upon power quality. An analytical solution characterizing the phenomenon of torque ripple has been obtained which is based upon a Fourier expansion of the time dependent features of the problem. Numerical results for torque ripple, some experimental data, determination of acceptable levels and methods of controlling it, are presented and discussed.

Reuter, R.C. Jr.

1980-09-01

174

How to protect a wind turbine from lightning  

NASA Technical Reports Server (NTRS)

Techniques for reducing the chances of lightning damage to wind turbines are discussed. The methods of providing a ground for a lightning strike are discussed. Then details are given on ways to protect electronic systems, generating and power equipment, blades, and mechanical components from direct and nearby lightning strikes.

Dodd, C. W.; Mccalla, T., Jr.; Smith, J. G.

1983-01-01

175

How to protect a wind turbine from lightning  

SciTech Connect

This book discusses techniques for reducing the chances of lightning damage to wind turbines. The methods of providing a ground for a lightning strike are discussed. Then details are given on ways to protect electronic systems, generating and power equipment, blades, and mechanical components from direct and nearby lightning strikes.

Dodd, C.W.; McCalla, T. Jr.; Smith, J.G.

1983-09-01

176

Lightning protection for wind turbine electronics  

NASA Astrophysics Data System (ADS)

Preventive measures for the protection of wind turbines from lightning strike damage are outlined. Lightning can dissipate up to a billion joules in less than a second while electronic components have tolerances in the microjoule range. Structural members may also suffer damage by mechanical stresses due to parallel conductance of lightning amperage; millions of volts are capable of causing flashovers or ionized arcing through air or poor insulation. Studies are cited to indicate that semiconductor device failures are dependent on pulse duration and amplitude. A solution is offered in the form of lightning ground rods, counterpoises, and interconnections which route lightning strike currents away from all electronics; additional shielding of the central electronics is also suggested. Various layers of protective measures are diagrammed, and the use of a transient suppressor to short excess current to ground is recommended.

Begley, D. L.; Dodd, C. W.; McCalla, T. M., Jr.

1981-12-01

177

Large, low cost composite wind turbine blades  

NASA Technical Reports Server (NTRS)

A woven roving E-glass tape, having all of its structural fibers oriented across the tape width was used in the manufacture of the spar for a wind turbine blade. Tests of a 150 ft composite blade show that the transverse filament tape is capable of meeting structural design requirements for wind turbine blades. Composite blades can be designed for interchangeability with steel blades in the MOD-1 wind generator system. The design, analysis, fabrication, and testing of the 150 ft blade are discussed.

Gewehr, H. W.

1979-01-01

178

Large Horizontal-Axis Wind Turbines  

NASA Technical Reports Server (NTRS)

The proceedings of a workshop held in Cleveland, July 28-30, 1981 are described. The workshop emphasized recent experience in building and testing large propeller-type wind turbines, expanding upon the proceedings of three previous DOE/NASA workshops at which design and analysis topics were considered. A total of 41 papers were presented on the following subjects: current and advanced large wind turbine systems, rotor blade design and manufacture, electric utility activities, research and supporting technology, meteorological characteristics for design and operation, and wind resources assessments for siting.

Thresher, R. W. (editor)

1982-01-01

179

Large horizontal axis wind turbine development  

NASA Technical Reports Server (NTRS)

An overview of the NASA activities concerning ongoing wind systems oriented toward utility application is presented. First-generation-technology large wind turbines were designed and are in operation at selected utility sites. In order to make a significant energy impact, costs of 2 to 3 cents per kilowatt hour must be achieved. The federal program continues to fund the development by industry of wind turbines which can meet the cost goals of 2 to 3 cents per kilowatt hour. Lower costs are achieved through the incorporation of new technology and innovative system design to reduce weight and increase energy capture.

Robbins, W. H.; Thomas, R. L.

1979-01-01

180

Load attenuating passively adaptive wind turbine blade  

DOEpatents

A method and apparatus for improving wind turbine performance by alleviating loads and controlling the rotor. The invention employs the use of a passively adaptive blade that senses the wind velocity or rotational speed, and accordingly modifies its aerodynamic configuration. The invention exploits the load mitigation prospects of a blade that twists toward feather as it bends. The invention includes passively adaptive wind turbine rotors or blades with currently preferred power control features. The apparatus is a composite fiber horizontal axis wind-turbine blade, in which a substantial majority of fibers in the blade skin are inclined at angles of between 15 and 30 degrees to the axis of the blade, to produces passive adaptive aeroelastic tailoring (bend-twist coupling) to alleviate loading without unduly jeopardizing performance.

Veers, Paul S. (Albuquerque, NM); Lobitz, Donald W. (Albuquerque, NM)

2003-01-01

181

Wind Turbine Micropitting Workshop: A Recap  

SciTech Connect

Micropitting is a Hertzian fatigue phenomenon that affects many wind turbine gearboxes, and it affects the reliability of the machines. With the major growth and increasing dependency on renewable energy, mechanical reliability is an extremely important issue. The U.S. Department of Energy has made a commitment to improving wind turbine reliability and the National Renewable Energy Laboratory (NREL) has started a gearbox reliability project. Micropitting as an issue that needed attention came to light through this effort. To understand the background of work that had already been accomplished, and to consolidate some level of collective understanding of the issue by acknowledged experts, NREL hosted a wind turbine micropitting workshop, which was held at the National Wind Technology Center in Boulder, Colorado, on April 15 and 16, 2009.

Sheng, S.

2010-02-01

182

Quantifying the hurricane risk to offshore wind turbines  

E-print Network

Quantifying the hurricane risk to offshore wind turbines Stephen Rosea , Paulina Jaramilloa,1. Turbine tower buckling has been observed in typhoons, but no offshore wind turbines have yet been built be destroyed by hurricanes in an offshore wind farm. We apply this model to estimate the risk to offshore wind

Jaramillo, Paulina

183

A Simplified Morphing Blade for Horizontal Axis Wind Turbines  

E-print Network

is known and the wind speed follows a Rayleigh distribution, the annual energy production of wind turbines energy production of the wind turbine containing morphing blades is 24.5 % to 69.7 % higher than the annual energy production of the wind turbine containing pitch fixed blades. Likewise, the annual energy

Recanati, Catherine

184

Trailing Edge Noise Model Applied to Wind Turbine Airfoils  

E-print Network

Trailing Edge Noise Model Applied to Wind Turbine Airfoils Franck Bertagnolio Risø-R-1633(EN) Risø Bertagnolio Title: Trailing Edge Noise Model Applied to Wind Turbine Airfoils Department: Wind Energy generation that are relevant to wind turbine technology with focus on trailing edge noise. Secondly, the so

185

IMPLEMENTATION OF WIND TURBINE CONTROLLERS W.E.Leithead  

E-print Network

. The standard commercial design of wind turbine is a horizontal-axis grid-connected up-wind machine of wind turbines, which are presently being developed, will include large-scale designs with a ratingIMPLEMENTATION OF WIND TURBINE CONTROLLERS D.J.Leith W.E.Leithead Department of Electronic

Duffy, Ken

186

Grid integration impacts on wind turbine design and development  

Microsoft Academic Search

This paper presents an overall perspective on contemporary issues like wind power plants and grid integration. The purpose is to present and discuss the impacts of emerging new grid connection requirements on modern wind turbines. The grid integration issue has caused several new challenges to the wind turbine design and development. The survival of different wind turbine concepts and controls

A. D. Hansen; N. A. Cutululis; P. Sorensen; F. Iov

2009-01-01

187

ACOUSTIC STUDY OF THE UD / GAMESA WIND TURBINE PROJECT  

E-print Network

/s). Maximum sound power is first produced by the wind turbine at the design wind speed. The study average sound levels are in the range of 34 to 56 dBA. · The maximum wind turbine sound level under design turbine sound level under design wind conditions at the closest university receivers (Class B noise zone

Firestone, Jeremy

188

Parametric evaluation of wind turbine noise  

SciTech Connect

In lieu of large single wind turbine installations, US Windpower, Burlington, Massachusetts is promoting the wind farm concept for wind power generation. A wind farm is an array of several small machines which are used to produce the equipment power of a single, large wind turbine. The smaller 50 KW machines manufactured by US Windpower, when used in an array to produce a large quantity of power, minimize the incidence of annoying infrasonic pulsing, nevertheless, the production of low frequency sound by wind farms still occurs. Measurements and theory clearly demonstrate that blade passage through the tower wake produces a sound pressure level frequency spectra consisting of harmonics of the blade passage frequency. The chief purpose of this work is to identify the importance of various tower and blade parameters that control blade passage noise generation.

Tocci, G.C.; Marcus, E.N.

1982-01-01

189

Active robust control of wind turbines  

NASA Astrophysics Data System (ADS)

The research work conducted in this thesis focuses on robustness of wind energy conversion system with respect to faults in pitch actuator in order to prevent unnecessary emergency shutdown, and keep the turbine operational without significant inefficiency in its overall performance. The objective is to investigate the feasibility of using a fault estimator and a light detection and ranging (LIDAR) system as additional sensors to design a suitable control system for wind turbines. Robust control technique is used to address these issues. Three controllers are proposed in this work that try to address sources of inaccuracy in wind turbine operation: An active fault tolerant controller is first designed using a fault estimator. It is shown that a set of locally robust controllers with respect to the fault, together with a suitable smooth mixing approach, manages to overcome the problem of faults in the pitch actuator. To address the wind-dependent behavior of turbines, a second controller is designed using the LIDAR sensor. In this configuration, LIDAR provides the look ahead wind information and generates a smooth scheduling signal to provide active robustness with respect to the changes in wind speed. Lastly, utilizing both the fault estimator and LIDAR, a 2-dimensional wind-dependent active fault tolerant controller is developed to control the wind turbine in region 3 of operation. The feasibility of the proposed ideas is verified in simulation. For this purpose, the US National Renewable Energy Laboratory's FAST code is used to model the 3-balded controls advanced research turbine. A discussion on practical considerations and ideas for future work are also presented.

Rezaei, Vahid

190

Atmospheric stability affects wind turbine power collection  

NASA Astrophysics Data System (ADS)

The power generated by a wind turbine largely depends on the wind speed. During time periods with identical hub-height wind speeds but different shapes to the wind profile, a turbine will produce different amounts of power. This variability may be induced by atmospheric stability, which affects profiles of mean wind speed, direction and turbulence across the rotor disk. Our letter examines turbine power generation data, segregated by atmospheric stability, in order to investigate power performance dependences at a West Coast North American wind farm. The dependence of power on stability is clear, regardless of whether time periods are segregated by three-dimensional turbulence, turbulence intensity or wind shear. The power generated at a given wind speed is higher under stable conditions and lower under strongly convective conditions: average power output differences approach 15%. Wind energy resource assessment and day ahead power forecasting could benefit from increased accuracy if atmospheric stability impacts were measured and appropriately incorporated in power forecasts, e.g., through the generation of power curves based on a range of turbulence regimes.

Wharton, Sonia; Lundquist, Julie K.

2012-03-01

191

A cross flow wind turbine  

Microsoft Academic Search

A theoretical analysis is presented of the operation of a type of crossflow turbine that depends for its action on angular momentum conversion rather than aerodynamic lift. Experimental results confirm the theoretical predictions to a satisfactory degree. These are, that while the turbine does develop a starting torque and has a stable torque-speed characteristic, it runs at low velocity ratio

M. J. Holgate

1977-01-01

192

Comparison of transient and quasi-steady aeroelastic analysis of wind turbine blade in steady wind conditions  

NASA Astrophysics Data System (ADS)

In the preliminary design stage of wind turbine blade, faster and simpler methods are preferred to predict the aeroelastic response of the blades in order to get an idea about the appropriateness of the blade stiffness. Therefore, in the present study, applicability of the quasi-steady aeroelastic analysis of wind turbine blade is investigated in terms of how accurately the quasi-steady aeroelastic analysis predicts the deformed state of the blade at certain azimuthal positions. For this purpose, comparative study of transient and quasi-steady aeroelastic analysis of a composite wind turbine blade in steady wind conditions is conducted. To perform the transient analysis, a multi-body wind turbine model is generated with almost rigid components except for the dynamic superelement blade that is inverse designed. Transient analysis of the multi body wind turbine system is performed by imposing constant rotational speed to the main shaft and bypassing the controller. Quasi-steady aeroelastic analysis of the same composite wind turbine blade is performed, by coupling a structural finite element solver with a blade element momentum tool, in steady wind conditions at different azimuthal positions including the effect of the centrifugal and gravitational forces. Results show that for the wind turbine system taken as the case study, reasonably good agreement is obtained between the tip deflections and flapwise root shear forces determined by the transient aeroelastic analysis of the wind turbine and quasi-steady aeroelastic analysis of the blade only.

Sargin, H.; Kayran, A.

2014-06-01

193

Wind Turbine Generator System Duration Test Report for the Mariah Power Windspire Wind Turbine  

SciTech Connect

This test was conducted as part of the U.S. Department of Energy's (DOE) Independent Testing project to help reduce the barriers of wind energy expansion by providing independent testing results for small turbines. In total, five turbines are being tested at the National Wind Technology Center (NWTC) as a part of the first round of this project. Duration testing is one of up to five tests that may be performed on the turbines. Other tests include power performance, safety and function, noise, and power quality tests. NWTC testing results provide manufacturers with reports that may be used to meet part of small wind turbine certification requirements. This duration test report focuses on the Mariah Power Windspire wind turbine.

Huskey, A.; Bowen, A.; Jager, D.

2010-05-01

194

Feature extraction method of wind turbine based on adaptive Morlet wavelet and SVD  

Microsoft Academic Search

Analyzing the vibration signals of wind turbine usually requires feature extraction. However, in many cases, to extract feature components becomes challenging and the applicability of information drops down due to the large amount of noise. In this paper, a new denoising method based on adaptive Morlet wavelet and singular value decomposition (SVD) is applied to feature extraction for wind turbine

Yonghua Jiang; Baoping Tang; Yi Qin; Wenyi Liu

2011-01-01

195

Wavelet-Based Signal Processing Method for Detecting Ice Accretion on Wind Turbines  

Microsoft Academic Search

This paper presents the performances of a new method for detecting ice accumulation on wind turbines. The presented method is based on constructing a multiresolution analysis (MRA) to extract frequency components present in the electric currents flowing out of an electric generator driven by a wind turbine. The foundations of the proposed ice detection method are established based on the

S. A. Saleh; R. Ahshan; C. R. Moloney

2012-01-01

196

Mathematical model for the analysis of wind-turbine wakes  

NASA Astrophysics Data System (ADS)

The concept of wind farms with clustered wind turbines at a given site seems to offer an attractive means for extracting wind power on a large scale. Techniques for minimizing the effect of upstream wind-turbine wakes on downstream wind turbines are needed to optimize overall performance of the wind-turbine array. A numerical model for prediction of the interaction of the wind turbine with the prevailing wind flow is described. The model is based on a numerical solution of the three-dimensional Navier-Stokes equations for the planetary boundary layer with the hydrostatic approximation. Three different hypothetical wind-turbine configurations are analyzed to demonstrate the utility of this model. Model predictions from the present study compare favorably with the basic characteristics of measured wind-turbine wakes.

Liu, M.-K.; Yocke, M. A.; Myers, T. C.

1983-02-01

197

A review of large wind turbine systems  

NASA Astrophysics Data System (ADS)

Research areas in the design and operation of large wind turbines in the U.S. and Europe are detailed, with attention given to current and completed programs. Theoretical work in the U.S. is focused on aerodynamics of blades, structural dynamics, control systems, and safety through safe life design, redundancy, and quality assurance. Work is continuing on wind characteristics over the rotor disk and design criteria with regard to cost/benefits and tradeoffs involving various configurations and materials for the rotor blades, placement, pitch control, blade articulation, the tower, the drive train, the gear box, a quill shaft, generator type, and reliability and maintenance. Costing models are being developed. Test experience has been gained through the manufacture and operation of the five Mod 0A, one Mod-1, four Mod-2, and one WTS-4 wind turbines. The European work on blade loading, wind turbine dimensioning, materials, wind structure, environmental impacts, and economics are reviewed, together with the operational experience with the Gedser, two Nibe, the Tvind, and Growian machines. Several countries are also testing smaller wind turbines manufactured indigenously or imported.

Selzer, H.; Lerner, J. I.

198

Mars Technologies Spawn Durable Wind Turbines  

NASA Technical Reports Server (NTRS)

To develop and test wind power technology for use on Mars, Ames Research Center turned to Northern Power Systems (NPS), based in Barre, Vermont. Ames awarded NPS an SBIR contract so the company could enhance their turbine’s function. Today, over 200 NASA-derived Northern Power 100s are in operation on Earth and have reduced carbon emissions by 50,000 tons annually.

2014-01-01

199

Wind tunnel tests of a free yawing downwind wind turbine  

NASA Astrophysics Data System (ADS)

This research paper presents preliminary results on a behavioural study of a free yawing downwind wind turbine. A series of wind tunnel tests was performed at the TU Delft Open Jet Facility with a three bladed downwind wind turbine and a rotor radius of 0.8 meters. The setup includes an off the shelf three bladed hub, nacelle and generator on which relatively flexible blades are mounted. The tower support structure has free yawing capabilities provided at the base. A short overview on the technical details of the experiment is given as well as a brief summary of the design process. The discussed test cases show that the turbine is stable while operating in free yawing conditions. Further, the effect of the tower shadow passage on the blade flapwise strain measurement is evaluated. Finally, data from the experiment is compared with preliminary simulations using DTU Wind Energy's aeroelastic simulation program HAWC2.

Verelst, D. R. S.; Larsen, T. J.; van Wingerden, J. W.

2014-12-01

200

Methods of making wind turbine rotor blades  

DOEpatents

A method of manufacturing a root portion of a wind turbine blade includes, in an exemplary embodiment, providing an outer layer of reinforcing fibers including at least two woven mats of reinforcing fibers, providing an inner layer of reinforcing fibers including at least two woven mats of reinforcing fibers, and positioning at least two bands of reinforcing fibers between the inner and outer layers, with each band of reinforcing fibers including at least two woven mats of reinforcing fibers. The method further includes positioning a mat of randomly arranged reinforcing fibers between each pair of adjacent bands of reinforcing fibers, introducing a polymeric resin into the root potion of the wind turbine blade, infusing the resin through the outer layer, the inner layer, each band of reinforcing fibers, and each mat of random reinforcing fibers, and curing the resin to form the root portion of the wind turbine blade.

Livingston, Jamie T. (Pensacola, FL); Burke, Arthur H. E. (Gulf Breeze, FL); Bakhuis, Jan Willem (Nijverdal, NL); Van Breugel, Sjef (Enschede, NL); Billen, Andrew (Daarlerveen, NL)

2008-04-01

201

The NASA Lewis large wind turbine program  

NASA Technical Reports Server (NTRS)

The program is directed toward development of the technology for safe, reliable, environmentally acceptable large wind turbines that have the potential to generate a significant amount of electricity at costs competitive with conventional electric generation systems. In addition, these large wind turbines must be fully compatible with electric utility operations and interface requirements. Advances are made by gaining a better understanding of the system design drivers, improvements in the analytical design tools, verification of design methods with operating field data, and the incorporation of new technology and innovative designs. An overview of the program activities is presented and includes results from the first and second generation field machines (Mod-OA, -1, and -2), the design phase of the third generation wind turbine (Mod-5) and the advanced technology projects. Also included is the status of the Department of Interior WTS-4 machine.

Thomas, R. L.; Baldwin, D. H.

1981-01-01

202

A doubly-fed permanent magnet generator for wind turbines  

E-print Network

Optimum extraction of energy from a wind turbine requires that turbine speed vary with wind speed. Existing solutions to produce constant-frequency electrical output under windspeed variations are undesirable due to ...

Thomas, Andrew J. (Andrew Joseph), 1981-

2004-01-01

203

Intimate Emptiness: The Flint Hills Wind Turbine Controversy  

E-print Network

, in the Flint Hills region of Kansas. The study is primarily concerned with the proposed introduction of wind turbines in Wabaunsee County, Kansas and examines the County's consideration of wind turbine projects between 2002 and 2004. The controversy...

Graham, Howard Russell

2008-07-28

204

Reduced Order Structural Modeling of Wind Turbine Blades  

E-print Network

Conventional three dimensional structural analysis methods prove to be expensive for the preliminary design of wind turbine blades. However, wind turbine blades are large slender members with complex cross sections. They can be accurately modeled...

Jonnalagadda, Yellavenkatasunil

2011-10-21

205

Multi-hazard Reliability Assessment of Offshore Wind Turbines  

E-print Network

A probabilistic framework is developed to assess the structural reliability of offshore wind turbines. Probabilistic models are developed to predict the deformation, shear force and bending moment demands on the support structure of wind turbines...

Mardfekri Rastehkenari, Maryam 1981-

2012-12-04

206

OUT Success Stories: Advanced Airfoils for Wind Turbines  

SciTech Connect

New airfoils have substantially increased the aerodynamic efficiency of wind turbines. It is clear that these new airfoils substantially increased energy output from wind turbines. Virtually all new blades built in this country today use these advanced airfoil designs.

Jones, J.; Green, B.

2000-08-31

207

Advanced wind turbine design studies: Advanced conceptual study  

Microsoft Academic Search

In conjunction with the US Department of Energy and the National Renewable Energy Laboratory's Advanced Wind Turbine Program, the Atlantic Orient Corporation developed preliminary designs for the next generation of wind turbines. These 50 kW and 350 kW turbines are based upon the concept of simplicity. By adhering to a design philosophy that emphasizes simplicity, we project that these turbines

P. Hughes; R. Sherwin

1994-01-01

208

Structural responses and power output of a wind turbine are strongly affected by the wind field acting on the wind turbine. Knowledge about the wind field and its  

E-print Network

ABSTRACT Structural responses and power output of a wind turbine are strongly affected by the wind affect the power output and structural responses of a wind turbine. Wind field characteristics are conventionally described by time averaged features, such as mean wind speed, turbulence intensity and power

Stanford University

209

Dynamic stall on wind turbine blades  

SciTech Connect

Dynamic loads must be predicted accurately in order to estimate the fatigue life of wind turbines operating in turbulent environments. Dynamic stall contributes to increased dynamic loads during normal operation of all types of horizontal-axis wind turbine (HAWTs). This report illustrates how dynamic stall varies throughout the blade span of a 10 m HAWT during yawed and unyawed operating conditions. Lift, drag, and pitching moment coefficients during dynamics stall are discussed. Resulting dynamic loads are presented, and the effects of dynamic stall on yaw loads are demonstrated using a yaw loads dynamic analysis (YAWDYN). 12 refs., 22 figs., 1 tab.

Butterfield, C.P.; Simms, D.; Scott, G. [National Renewable Energy Lab., Golden, CO (United States)] [National Renewable Energy Lab., Golden, CO (United States); Hansen, A.C. [Utah Univ., Salt Lake City, UT (United States)] [Utah Univ., Salt Lake City, UT (United States)

1991-12-01

210

Amplitude modulation of wind turbine noise  

E-print Network

Due to swish and thump amplitude modulation, the noise of wind turbines cause more annoyance than other environmental noise of the same average level. The wind shear accounts for the thump modulation (van den Berg effect). Making use of the wind speed measurements at the hub height, as well as at the top and the bottom of the rotor disc (Fig.1), the non-standard wind profile is applied. It causes variations in the A-weighted sound pressure level, LpA. The difference between the maximum and minimum of LpA characterizes thump modulation (Fig.2).

Makarewicz, Rufin

2013-01-01

211

RESEARCH ARTICLE Dynamic wind loads and wake characteristics of a wind turbine  

E-print Network

design of the wind turbines operating in atmospheric boundary layer winds. 1 Introduction With the oilRESEARCH ARTICLE Dynamic wind loads and wake characteristics of a wind turbine model of the unsteady vortex and turbulent flow structures in the near wake of a horizontal axis wind turbine model

Hu, Hui

212

Shear and Turbulence Estimates for Calculation of Wind Turbine Loads and Responses Under Hurricane Strength Winds  

NASA Astrophysics Data System (ADS)

Schwartz et al. (2010) recently reported that the total gross energy-generating offshore wind resource in the United States in waters less than 30m deep is approximately 1000 GW. Estimated offshore generating capacity is thus equivalent to the current generating capacity in the United States. Offshore wind power can therefore play important role in electricity production in the United States. However, most of this resource is located along the East Coast of the United States and in the Gulf of Mexico, areas frequently affected by tropical cyclones including hurricanes. Hurricane strength winds, associated shear and turbulence can affect performance and structural integrity of wind turbines. In a recent study Rose et al. (2012) attempted to estimate the risk to offshore wind turbines from hurricane strength winds over a lifetime of a wind farm (i.e. 20 years). According to Rose et al. turbine tower buckling has been observed in typhoons. They concluded that there is "substantial risk that Category 3 and higher hurricanes can destroy half or more of the turbines at some locations." More robust designs including appropriate controls can mitigate the risk of wind turbine damage. To develop such designs good estimates of turbine loads under hurricane strength winds are essential. We use output from a large-eddy simulation of a hurricane to estimate shear and turbulence intensity over first couple of hundred meters above sea surface. We compute power spectra of three velocity components at several distances from the eye of the hurricane. Based on these spectra analytical spectral forms are developed and included in TurbSim, a stochastic inflow turbulence code developed by the National Renewable Energy Laboratory (NREL, http://wind.nrel.gov/designcodes/preprocessors/turbsim/). TurbSim provides a numerical simulation including bursts of coherent turbulence associated with organized turbulent structures. It can generate realistic flow conditions that an operating turbine would encounter under hurricane strength winds. These flow fields can be used to estimate wind turbine loads and responses with AeroDyn (http://wind.nrel.gov/designcodes/simulators/aerodyn/) and FAST (http://wind.nrel.gov/designcodes/simulators/fast/) codes also developed by NREL.

Kosovic, B.; Bryan, G. H.; Haupt, S. E.

2012-12-01

213

Modal testing of a rotating wind turbine  

NASA Astrophysics Data System (ADS)

A testing technique was developed to measure the modes of vibration of a rotating vertical-axis wind turbine. This technique was applied to the Sandia Two-Meter Turbine, where the changes in individual modal frequencies as a function of the rotational speed were tracked from 0 rpm (parked) to 600 rpm. During rotational testing, the structural response was measured using a combination of strain gages and accelerometers, passing the signals through slip rings. Excitation of the turbine structure was provided by a scheme which suddenly released a pretensioned cable, thus plucking the turbine as it was rotating at a set speed. In addition to calculating the real modes of the parked turbine, the modes of the rotating turbine were also determined at several rotational speeds. The modes of the rotating system proved to be complex due to centrifugal and Coriolis effects. The modal data for the parked turbine were used to update a finite-element model. Also, the measured modal parameters for the rotating turbine were compared to the analytical results, thus verifying the analytical procedures used to incorporate the effects of the rotating coordinate system.

Carne, T. G.; Nord, A. R.

1982-11-01

214

Scour around an offshore wind turbine W.F. Louwersheimer  

E-print Network

Scour around an offshore wind turbine MSc Thesis W.F. Louwersheimer January, 2007 Delft University #12;Scour around an offshore wind turbine Delft University of Technology Ballast Nedam - Egmond iii Scour around an offshore wind turbine W.F. Louwersheimer Student number 1067419 January, 2007

Langendoen, Koen

215

RELIABILITY COMPARISON MODELS FOR OFFSHORE WIND TURBINES (OWT)  

E-print Network

RELIABILITY COMPARISON MODELS FOR OFFSHORE WIND TURBINES (OWT) Yizhou Lu, T. M. Delorm, A. Christou of survivor functions R(t) of drive-trains, after 1 year of operation, between Offshore Wind Turbine (OWT) vs of the reliability of these 5 Types Surrogate failure rate data Onshore wind turbines (OT) 1-1.5MW CONCLUSIONS

Bernstein, Joseph B.

216

Initialization of wind turbine models in power system dynamics simulations  

Microsoft Academic Search

As a result of increasing environmental concern, increasing amounts of electricity are generated from renewable sources. One way of generating electricity from renewable sources is to use wind turbines. A tendency to erect more wind turbines can be observed. As a result of this, in the near future wind turbines may start to influence the behavior of electrical power systems.

J. G. Slootweg; H. Polinder; W. L. Kling

2001-01-01

217

On wind turbine power performance measurements at inclined airflow  

Microsoft Academic Search

The average airflow inclination in complex terrain may be substantial. The airflow inclination affects wind turbine performance and also affects the cup anemometer being used in power performance measurements. In this article the overall dependence of the power curve on inclined airflow is analysed for its influence on both the wind turbine and the cup anemometer. The wind turbine performance

T. F. Pedersen

2004-01-01

218

Control of Wind Turbines for Power Regulation and  

E-print Network

Control of Wind Turbines for Power Regulation and Load Reduction Juan Jose Garcia Quirante Kongens regulation and load reduction and their ensemble in a variable-speed wind turbine. The power regulation aspects of mathematical modelling of wind turbines, and especially the control methods suited for power

219

Study on Lightning Protection Methods for Wind Turbine Blades  

Microsoft Academic Search

Lightning protection measures for wind turbines are becoming important as the use of wind turbines is increasing rapidly along with its capacity and height. In order to understand the manner of lightning attachment to wind turbine blades, experiments with various types of blade samples were conducted. Experimental studies revealed following issues. Regarding a non-conductive blade sample, the 50% flashover voltage

Takehiro Naka; Nilesh J. Vasa; Shigeru Yokoyama; Atsushi Wada; Akira Asakawa; Hideki Honda; Kazuhisa Tsutsumi; Shinji Arinaga

2005-01-01

220

Modelling of transient wind turbine loads during pitch motion  

E-print Network

In connection with the design of wind turbines and their control algorithms, the transient loads, especially the conditions experienced in connection with helicopters. First of all, wind turbines are designed for powerModelling of transient wind turbine loads during pitch motion Niels.N. Sørensen, Helge Aa. Madsen

221

AIAA-2001-0047 PARAMETRIC MODELS FOR ESTIMATING WIND TURBINE  

E-print Network

AIAA-2001-0047 1 PARAMETRIC MODELS FOR ESTIMATING WIND TURBINE FATIGUE LOADS FOR DESIGN Lance. INTRODUCTION Design constraints for wind turbine structures fall into either extreme load or fatigue categories 94305-4020 ABSTRACT International standards for wind turbine certification depend on finding long

Sweetman, Bert

222

Design Loads for Wind Turbines using the Environmental Contour Method  

E-print Network

Design Loads for Wind Turbines using the Environmental Contour Method Korn Saranyasoontorn, TX 78712 When interest is in establishing ultimate design loads for wind turbines such that a service probabilistic design approaches for design of wind turbines against extreme limit states. Several different

Manuel, Lance

223

Vortex Lattice Modelling of Winglets on Wind Turbine Blades  

E-print Network

vortex lattice code and a fast design algorithm for a horizontal axis wind turbine under steady and a fast design algorithm for a horizontal axis wind turbine under steady conditions has been developed. 2Vortex Lattice Modelling of Winglets on Wind Turbine Blades Mads Døssing Risø-R-1621(EN) Risø

224

PARAMETRIC MODELS FOR ESTIMATING WIND TURBINE FATIGUE LOADS FOR DESIGN  

E-print Network

1 PARAMETRIC MODELS FOR ESTIMATING WIND TURBINE FATIGUE LOADS FOR DESIGN Lance Manuel1 Paul S loads. #12;2 INTRODUCTION Design constraints for wind turbine structures fall into either extreme load-4020 ABSTRACT International standards for wind turbine certification depend on finding long-term fatigue load

Sweetman, Bert

225

Ris-R-1352(EN) Models for Wind Turbines  

E-print Network

it possible to identify such stability problems already in the design phase of a wind turbine structureRisø-R-1352(EN) Models for Wind Turbines ­ a Collection Andreas Baumgart Gunner C. Larsen, Morten H is to supply new approaches to stability investigations of wind turbines. The author's opinion

226

Ris R1024EN Design of the Wind Turbine  

E-print Network

Ris R1024EN Design of the Wind Turbine Airfoil Family RIS AXX Kristian S. Dahl, Peter Fuglsang Ris National Laboratory, Roskilde, Denmark December 1998 #12;Abstract A method for design of wind turbine Wind turbine airfoil characteristics 6 3 Design method 7 3.1 Design algorithm 7 3.2 Geometry

227

Experimental characterization of vertical-axis wind turbine noise.  

PubMed

Vertical-axis wind turbines are wind-energy generators suitable for use in urban environments. Their associated noise thus needs to be characterized and understood. As a first step, this work investigates the relative importance of harmonic and broadband contributions via model-scale wind-tunnel experiments. Cross-spectra from a pair of flush-mounted wall microphones exhibit both components, but further analysis shows that the broadband dominates at frequencies corresponding to the audible range in full-scale operation. This observation has detrimental implications for noise-prediction reliability and hence also for acoustic design optimization. PMID:25618090

Pearson, C E; Graham, W R

2015-01-01

228

Flow separation on wind turbines blades  

Microsoft Academic Search

In the year 2000, 15GW of wind power was installed throughout the world, producing 100PJ\\u000aof energy annually. This contributes to the total electricity demand by only 0.2%. Both the\\u000ainstalled power and the generated energy are increasing by 30% per year world-wide. If the\\u000aairflow over wind turbine blades could be controlled fully, the generation efficiency and thus\\u000athe

G. P. Corten

2001-01-01

229

Built-Environment Wind Turbine Roadmap  

SciTech Connect

Although only a small contributor to total electricity production needs, built-environment wind turbines (BWTs) nonetheless have the potential to influence the public's consideration of renewable energy, and wind energy in particular. Higher population concentrations in urban environments offer greater opportunities for project visibility and an opportunity to acquaint large numbers of people to the advantages of wind projects on a larger scale. However, turbine failures will be equally visible and could have a negative effect on public perception of wind technology. This roadmap provides a framework for achieving the vision set forth by the attendees of the Built-Environment Wind Turbine Workshop on August 11 - 12, 2010, at the U.S. Department of Energy's National Renewable Energy Laboratory. The BWT roadmap outlines the stakeholder actions that could be taken to overcome the barriers identified. The actions are categorized as near-term (0 - 3 years), medium-term (4 - 7 years), and both near- and medium-term (requiring immediate to medium-term effort). To accomplish these actions, a strategic approach was developed that identifies two focus areas: understanding the built-environment wind resource and developing testing and design standards. The authors summarize the expertise and resources required in these areas.

Smith, J.; Forsyth, T.; Sinclair, K.; Oteri, F.

2012-11-01

230

On damage detection in wind turbine gearboxes using outlier analysis  

NASA Astrophysics Data System (ADS)

The proportion of worldwide installed wind power in power systems increases over the years as a result of the steadily growing interest in renewable energy sources. Still, the advantages offered by the use of wind power are overshadowed by the high operational and maintenance costs, resulting in the low competitiveness of wind power in the energy market. In order to reduce the costs of corrective maintenance, the application of condition monitoring to gearboxes becomes highly important, since gearboxes are among the wind turbine components with the most frequent failure observations. While condition monitoring of gearboxes in general is common practice, with various methods having been developed over the last few decades, wind turbine gearbox condition monitoring faces a major challenge: the detection of faults under the time-varying load conditions prevailing in wind turbine systems. Classical time and frequency domain methods fail to detect faults under variable load conditions, due to the temporary effect that these faults have on vibration signals. This paper uses the statistical discipline of outlier analysis for the damage detection of gearbox tooth faults. A simplified two-degree-of-freedom gearbox model considering nonlinear backlash, time-periodic mesh stiffness and static transmission error, simulates the vibration signals to be analysed. Local stiffness reduction is used for the simulation of tooth faults and statistical processes determine the existence of intermittencies. The lowest level of fault detection, the threshold value, is considered and the Mahalanobis squared-distance is calculated for the novelty detection problem.

Antoniadou, Ifigeneia; Manson, Graeme; Dervilis, Nikolaos; Staszewski, Wieslaw J.; Worden, Keith

2012-04-01

231

Flutter of Darrieus wind turbine blades  

NASA Technical Reports Server (NTRS)

The testing of Darrieus wind turbines has indicated that under certain conditions, serious vibrations of the blades can occur, involving flatwise bending, torsion, and chordwise bending. A theoretical method of predicting the aeroelastic stability of the coupled bending and torsional motion of such blades with a view to determining the cause of these vibrations, and a means of suppressing them was developed.

Ham, N. D.

1978-01-01

232

Optimization method for wind turbine rotors  

Microsoft Academic Search

This paper presents a recently developed numerical multi-disciplinary optimization method for design of horizontal axis wind turbines. The method allows multiple constraints. The objective was minimum cost of energy, determined by the design giving fatigue and extreme loads and the annual production of energy. Time domain aeroelastic calculations and Rainflow counting provided the life time equivalent fatigue loads. A semi-empirical

P. Fuglsang; H. A. Madsen

1999-01-01

233

PARAMETRIC STUDY FOR LARGE WIND TURBINE BLADES  

Microsoft Academic Search

Abstract This report presents the results of a study of various wind turbine blade design parameters as a function of blade length in the range from 30 meters to 70 meters The results have been summarized in dimensional and non - dimensional formats to aid in interpretation The parametric review estimated peak power and annual energy capture for megawatt scale

Tpi Composites

2001-01-01

234

LOAD DATA ANALYSIS FOR WIND TURBINE GEARBOXES  

Microsoft Academic Search

Gearboxes for wind turbines have to ensure highest reliability over a period of approximately 20 years, withstanding high dynamic loads. At the same time lightweight design and cost minimization are required. These demands can only be met by a thought-out design, high-quality materials, high production quality and maintenance. In order to design a reliable and lightweight gearbox it is necessary

Bernd Niederstucke; Andreas Anders; Peter Dalhoff; Rainer Grzybowski; Germanischer Lloyd

235

Infrasound from Wind Turbines Could Affect Humans  

ERIC Educational Resources Information Center

Wind turbines generate low-frequency sounds that affect the ear. The ear is superficially similar to a microphone, converting mechanical sound waves into electrical signals, but does this by complex physiologic processes. Serious misconceptions about low-frequency sound and the ear have resulted from a failure to consider in detail how the ear…

Salt, Alec N.; Kaltenbach, James A.

2011-01-01

236

Infrasound From Wind Turbines Could Affect Humans  

Microsoft Academic Search

Wind turbines generate low-frequency sounds that affect the ear. The ear is superficially similar to a microphone, converting mechanical sound waves into electrical signals, but does this by complex physiologic processes. Serious misconceptions about low-frequency sound and the ear have resulted from a failure to consider in detail how the ear works. Although the cells that provide hearing are insensitive

Alec N. Salt; James A. Kaltenbach

2011-01-01

237

Wooden wind turbine blade manufacturing process  

DOEpatents

A wooden wind turbine blade is formed by laminating wood veneer in a compression mold having the exact curvature needed for one side of the blade, following which the other side of the blade is ground flat along its length but twisted with respect to the blade axis.

Coleman, Clint (Warren, VT)

1986-01-01

238

Wind turbine performance under icing conditions  

SciTech Connect

The effects of rime ice on horizontal axis wind turbine performance were estimated. For typical supercooled fog conditions found in cold northern regions, four rime ice accretions on the S809 wind turbine airfoil were predicted using the NASA LEWICE code. The resulting airfoil/ice profile combinations were wind tunnel tested to obtain the lift, drag, and pitching moment characteristics over the Reynolds number range 1--2 {times} 10{sup 6}. These data were used in the PROPID wind turbine performance prediction code to predict the effects of rime ice on a 450-kW rated-power, 28.7-m diameter turbine operated under both stall-regulated and variable-speed/variable-pitch modes. Performance losses on the order of 20% were observed for the variable-speed/variable-pitch rotor. For the stall-regulated rotor, however, a relatively small rime ice profile yielded significantly larger performance losses. For a larger 0.08c-long rime ice protrusion, however, the rated peak power was exceeded by 16% because at high angles the rime ice shape acted like a leading edge flap, thereby increasing the airfoil C{sub l,max} and delaying stall.

Jasinski, W.J.; Noe, S.C.; Selig, M.S.; Bragg, M.B. [Univ. of Illinois, Urbana, IL (United States). Dept. of Aeronautical and Astronautical Engineering

1998-02-01

239

Fuzzy PID Controller for Wind Turbines  

Microsoft Academic Search

PID and fuzzy PID controller are applied into the wind turbine with nonlinear mathematical model. PID control has simple principle and its parameters setting are rather easy. Fuzzy control need not to establish the mathematical of the control system and has strong robustness. Fuzzy PID control is combined with PID control and fuzzy control. The advantages of fuzzy PID control

Xiao Cheng; Zhang Lei; Yan Junqiu

2009-01-01

240

Evaluation of airfoils for small wind turbines  

Technology Transfer Automated Retrieval System (TEKTRAN)

A new set of blades have been designed, fabricated, and tested at the United States Department of Agriculture-Agricultural Research Service-Conservation and Production Research Laboratory in Bushland, Texas in an attempt to improve the overall performance of small (1-10 kilowatt) wind turbines. The ...

241

Mod-2 wind turbine loads test correlations  

SciTech Connect

The Boeing Company, under contract to the Electric Power Research Institute (EPRI), has completed a test program on the Mod-2 wind turbines at Goodnoe Hills, Washington. The objectives were to update fatigue load spectra for different sites, to measure vortex generator effects, and to evaluate rotational sampling techniques. This paper presents the results of these tests and assesses the adequacy of prediction techniques.

Zimmerman, D.K.; Shipley, S.A.

1986-02-01

242

Wind Turbine Tribology Seminar - A Recap  

SciTech Connect

Tribology is the science and engineering of interacting surfaces in relative motion. It includes the study and application of the principles of friction, lubrication, and wear. It is an important phenomenon that not only impacts the design and operation of wind turbine gearboxes, but also their subsequent maintenance requirements and overall reliability. With the major growth and increasing dependency on renewable energy, mechanical reliability is an extremely important issue. The Wind Turbine Tribology Seminar was convened to explore the state-of-the-art in wind turbine tribology and lubricant technologies, raise industry awareness of a very complex topic, present the science behind each technology, and identify possible R&D areas. To understand the background of work that had already been accomplished, and to consolidate some level of collective understanding of tribology by acknowledged experts, the National Renewable Energy Laboratory (NREL), Argonne National Laboratory (ANL), and the U.S. Department of Energy (DOE) hosted a wind turbine tribology seminar. It was held at the Renaissance Boulder Flatiron Hotel in Broomfield, Colorado on November 15-17, 2011. This report is a summary of the content and conclusions. The presentations given at the meeting can be downloaded. Interested readers who were not at the meeting may wish to consult the detailed publications listed in the bibliography section, obtain the cited articles in the public domain, or contact the authors directly.

Errichello, R.; Sheng, S.; Keller, J.; Greco, A.

2012-02-01

243

Latest wind turbine designs bolster industry confidence  

Microsoft Academic Search

This article describes a new generation of turbine designs, along with government incentives and support, that are prompting windpower projects with projected performance and economics that seem to satisfy the financiers. Wind-energy powerplants have been struggling to enter that promised land of commercially acceptable electric generation options for almost a decade. Ironically, some environmental groups, once ardent supporters of the

Makansi

1994-01-01

244

A Gust Model for Wind Turbine Design  

Microsoft Academic Search

A new method, so called constrained stochastic simulation, has been developed in order to generate extreme gust time series, to be used to calculate the extreme loading of wind turbines. A constrained simulation corresponds to the addition, in a special manner, of turbulence and a deterministic part (which resembles the auto correlation function of turbulence). The stochastic gusts produced in

Wim Bierbooms

2004-01-01

245

Optimization of wind turbine design for SWECS  

Microsoft Academic Search

Current research to optimize wind turbine designs centers on the most important parameter, the useful lifetime of the rotor assembly. A rotor design which promises to extend the lifetime of the full rotor assembly is discussed. That design improvement includes the integration of a teetered rotor hub and a delta-3 angle. This design concept was proven in helicopter and rotor

P. J. Bryant

1983-01-01

246

Power Performance Test Report for the SWIFT Wind Turbine  

SciTech Connect

This report summarizes the results of a power performance test that NREL conducted on the SWIFT wind turbine. This test was conducted in accordance with the International Electrotechnical Commission's (IEC) standard, Wind Turbine Generator Systems Part 12: Power Performance Measurements of Electricity Producing Wind Turbines, IEC 61400-12-1 Ed.1.0, 2005-12. However, because the SWIFT is a small turbine as defined by IEC, NREL also followed Annex H that applies to small wind turbines. In these summary results, wind speed is normalized to sea-level air density.

Mendoza, I.; Hur, J.

2012-12-01

247

The Mod-2 wind turbine development project  

NASA Technical Reports Server (NTRS)

A major phase of the Federal Wind Energy Program, the Mod-2 wind turbine, a second-generation machine developed by the Boeing Engineering and Construction Co. for the U.S. Department of Energy and the Lewis Research Center of the National Aeronautics and Space Administration, is described. The Mod-2 is a large (2.5-MW power rating) horizontal-axis wind turbine designed for the generation of electrical power on utility networks. Three machines were built and are located in a cluster at Goodnoe Hills, Washington. All technical aspects of the project are described: design approach, significant innovation features, the mechanical system, the electrical power system, the control system, and the safety system.

Linscott, B. S.; Dennett, J. T.; Gordon, L. H.

1981-01-01

248

Effects of Changing Atmospheric Conditions on Wind Turbine Performance (Poster)  

SciTech Connect

Multi-megawatt, utility-scale wind turbines operate in turbulent and dynamic winds that impact turbine performance in ways that are gradually becoming better understood. This poster presents a study made using a turbulent flow field simulator (TurbSim) and a Turbine aeroelastic simulator (FAST) of the response of a generic 1.5 MW wind turbine to changing inflow. The turbine power output is found to be most sensitive to wind speed and turbulence intensity, but the relationship depends on the wind speed with respect to the turbine's rated wind speed. Shear is found to be poorly correlated to power. A machine learning method called 'regression trees' is used to create a simple model of turbine performance that could be used as part of the wind resource assessment process. This study has used simple flow fields and should be extended to more complex flows, and validated with field observations.

Clifton, A.

2012-12-01

249

Performance characteristics of aerodynamically optimum turbines for wind energy generators  

NASA Technical Reports Server (NTRS)

This paper presents a brief discussion of the aerodynamic methodology for wind energy generator turbines, an approach to the design of aerodynamically optimum wind turbines covering a broad range of design parameters, some insight on the effect on performance of nonoptimum blade shapes which may represent lower fabrication costs, the annual wind turbine energy for a family of optimum wind turbines, and areas of needed research. On the basis of the investigation, it is concluded that optimum wind turbines show high performance over a wide range of design velocity ratios; that structural requirements impose constraints on blade geometry; that variable pitch wind turbines provide excellent power regulation and that annual energy output is insensitive to design rpm and solidity of optimum wind turbines.

Rohrbach, C.; Worobel, R.

1975-01-01

250

Mod-2 wind turbine field operations experiment  

NASA Technical Reports Server (NTRS)

The three-machine, 7.5 MW Goodnoe Hills located near Goldendale, Washington and is now in a research/experimental operations phase that offers a unique opportunity to study the effects of single and multiple wind turbines interacting with each other, the power grid; and the environment. Following a brief description of the turbine and project history, this paper addresses major problem areas and research and development test results. Field operations, both routine and nonroutine, are discussed. Routine operation to date has produced over 13,379,000 KWh of electrical energy during 11,064 hr of rotation. Nonroutine operation includes suspended activities caused by a crack in the low speed shaft that necessitated a redesign and reinstallation of this assembly on all three turbines. With the world's largest cluster back in full operation, two of the turbines will be operated over the next years to determine their value as energy producer. The third unit will be used primarily for conducting research tests requiring configuration changes to better understand the wind turbine technology. Technical areas summarized pertain to system performance and enhancements. Specific research tests relating to acoustics, TV interference, and wake effects conclude the paper.

Gordon, L. H.

1985-01-01

251

Mod-2 wind turbine field operations experiment  

NASA Astrophysics Data System (ADS)

The three-machine, 7.5 MW Goodnoe Hills located near Goldendale, Washington and is now in a research/experimental operations phase that offers a unique opportunity to study the effects of single and multiple wind turbines interacting with each other, the power grid; and the environment. Following a brief description of the turbine and project history, this paper addresses major problem areas and research and development test results. Field operations, both routine and nonroutine, are discussed. Routine operation to date has produced over 13,379,000 KWh of electrical energy during 11,064 hr of rotation. Nonroutine operation includes suspended activities caused by a crack in the low speed shaft that necessitated a redesign and reinstallation of this assembly on all three turbines. With the world's largest cluster back in full operation, two of the turbines will be operated over the next years to determine their value as energy producer. The third unit will be used primarily for conducting research tests requiring configuration changes to better understand the wind turbine technology. Technical areas summarized pertain to system performance and enhancements. Specific research tests relating to acoustics, TV interference, and wake effects conclude the paper.

Gordon, L. H.

1985-12-01

252

Power control of a wind farm with active stall wind turbines and AC grid connection  

E-print Network

Power control of a wind farm with active stall wind turbines and AC grid connection Anca D. Hansen1 on the wind farm level. The ability of active stall wind farms with AC grid connection to regulate the power. Keywords: wind farm control, active stall wind turbine, power system control 1 Introduction The recent

253

Modern control design for flexible wind turbines  

NASA Astrophysics Data System (ADS)

Control can improve energy capture and reduce dynamic loads in wind turbines. In the 1970s and 1980s wind turbines used classical control designs to regulate power and speed. The methods used, however, were not always successful. These systems often had bandwidths large enough to destabilize low-damped flexible modes leading to high dynamic load fatigue failures. Modern turbines are larger, mounted on taller towers, and are more dynamically active than their predecessors. Control systems to regulate turbine power and maintain stable closed-loop behavior in the presence of turbulent wind inflow will be critical for these designs. New advanced control approaches and paradigms must account for low-damped flexible modes in order to reduce structural dynamic loading and achieve the 20--25 year operational life required of today's machines. This thesis applies modern state-space control design methods to a two-bladed teetering hub upwind machine located at the National Wind Technology Center. The design objective is to regulate turbine speed and enhance damping in several low-damped flexible modes of the turbine. Starting with simple control algorithms based on linear models, complexity is added incrementally until the desired performance is firmly established. The controls approach is based on the Disturbance Accommodating Control (DAC) method and provides accountability for wind-speed fluctuations. First, controls are designed using the single control input rotor collective pitch to stabilize the 1st drive-train torsion as well as the tower 1st fore-aft bending modes. Generator torque is then incorporated as an additional control input. This reduces some of the demand placed on the rotor collective pitch control system and enhances 1st drive train torsion mode damping. Individual blade pitch control is then used to attenuate wind disturbances having spatial variation over the rotor and effectively reduces blade flap deflections due to wind shear. Finally, results from these modern controls are compared to results from simpler classical controls in order to assess modern controller performance. These modern controls are shown to more effectively mitigate tower fore-aft motion, drive-train shaft torsion moments, and blade root flap bending moments when compared to the classical control approaches.

Wright, Alan Duane

254

Augmented Adaptive Control of a Wind Turbine in the Presence of Structural Modes  

NASA Technical Reports Server (NTRS)

Wind turbines operate in highly turbulent environments resulting in aerodynamic loads that can easily excite turbine structural modes, potentially causing component fatigue and failure. Two key technology drivers for turbine manufacturers are increasing turbine up time and reducing maintenance costs. Since the trend in wind turbine design is towards larger, more flexible turbines with lower frequency structural modes, manufacturers will want to develop methods to operate in the presence of these modes. Accurate models of the dynamic characteristics of new wind turbines are often not available due to the complexity and expense of the modeling task, making wind turbines ideally suited to adaptive control. In this paper, we develop theory for adaptive control with rejection of disturbances in the presence of modes that inhibit the controller. We use this method to design an adaptive collective pitch controller for a high-fidelity simulation of a utility-scale, variable-speed wind turbine operating in Region 3. The objective of the adaptive pitch controller is to regulate generator speed, accommodate wind gusts, and reduce the interference of certain structural modes in feedback. The control objective is accomplished by collectively pitching the turbine blades. The adaptive pitch controller for Region 3 is compared in simulations with a baseline classical Proportional Integrator (PI) collective pitch controller.

Frost, Susan A.; Balas, Mark J.; Wright, Alan D.

2010-01-01

255

Analysis of the Flicker Level Produced by a Fixed-Speed Wind Turbine  

NASA Astrophysics Data System (ADS)

In this article, the analysis of the flicker emission during continuous operation of a mid-scale fixed-speed wind turbine connected to a distribution system is presented. Flicker emission is investigated based on simulation results, and the dependence of flicker emission on short-circuit capacity, grid impedance angle, mean wind speed, and wind turbulence is analyzed. The simulations were conducted in different programs in order to provide a more realistic wind emulation and detailed model of mechanical and electrical components of the wind turbine. Such aim is accomplished by using FAST (Fatigue, Aerodynamics, Structures, and Turbulence) to simulate the mechanical parts of the wind turbine, Simulink/MatLab to simulate the electrical system, and TurbSim to obtain the wind model. The results show that, even for a small wind generator, the flicker level can limit the wind power capacity installed in a distribution system.

Suppioni, Vinicius; P. Grilo, Ahda

2013-10-01

256

Lightning discharges produced by wind turbines  

NASA Astrophysics Data System (ADS)

observations with a 3-D Lightning Mapping Array and high-speed video are presented and discussed. The first set of observations shows that under certain thunderstorm conditions, wind turbine blades can produce electric discharges at regular intervals of ~3 s in relation to its rotation, over periods of time that range from a few minutes up to hours. This periodic effect has not been observed in static towers indicating that the effect of rotation is playing a critical role. The repeated discharges can occur tens of kilometers away from electrically active thunderstorm areas and may or may not precede a fully developed upward lightning discharge from the turbine. Similar to rockets used for triggering lightning, the fast movement of the blade tip plays an important role on the initiation of the discharge. The movement of the rotor blades allows the tip to "runaway" from the generated corona charge. The second observation is an uncommon upward/downward flash triggered by a wind turbine. In that flash, a negative upward leader was initiated from a wind turbine without preceding lightning activity. The flash produced a negative cloud-to-ground stroke several kilometers from the initiation point. The third observation corresponds to a high-speed video record showing simultaneous upward positive leaders from a group of wind turbines triggered by a preceding intracloud flash. The fact that multiple leaders develop simultaneously indicates a poor shielding effect among them. All these observations provide some special features on the initiation of lightning by nonstatic and complex tall structures.

Montanyà, Joan; Velde, Oscar; Williams, Earle R.

2014-02-01

257

Advanced CFD methods for wind turbine analysis  

NASA Astrophysics Data System (ADS)

Horizontal-axis wind turbines operate in a complex, inherently unsteady aerodynamic environment. Even when the rotor is not stalled, the flow over the blades is dominated by three-dimensional (3-D) effects. Stall is accompanied by massive flow separation and vortex shedding over the suction surface of the blades. Under yawed conditions, dynamic stall may be present as well. In all operating conditions, there is bluff-body shedding from the turbine nacelle and support structure which interacts with the rotor wake. In addition, the high aspect ratios of wind turbine blades make them very flexible, leading to substantial aeroelastic deformation of the blades, altering the aerodynamics. Finally, when situated in a wind farm, turbines must operate in the unsteady wake of upstream neighbors. Though computational fluid dynamics (CFD) has made significant inroads as a research tool, simple, inexpensive methods, such as blade element momentum (BEM) theory, are still the workhorses in wind turbine design and aeroelasticity applications. These methods generally assume a quasi-steady flowfield and use two-dimensional aerodynamic approximations with very limited empirical 3-D corrections. As a result, they are unable to accurately predict rotor loads near the edges of the operating envelope. CFD methods make very few limiting assumptions about the flowfield, and thus have much greater potential for predicting these flows. In this work, a range of unstructured grid CFD techniques for predicting wind turbine loads and aeroelasticity has been developed and applied to a wind turbine configuration of interest. First, a nearest neighbor search algorithm based on a k-dimensional tree data structure was used to improve the computational efficiency of an approximate unsteady actuator blade method. This method was then shown to predict root and tip vortex locations and strengths similar to an overset method on the same background mesh, but without the computational expense of modeling the blade surfaces. A hybrid Reynolds-averaged Navier-Stokes / Large Eddy Simulation (HRLES) turbulence model, previously developed for structured grids, was extended to an unstructured framework. It was demonstrated to improve predictions of unsteady loading and shedding frequency in massively separated cases. The sensitivity of the model to highly stretched grid topologies was also explored. For aeroelastic predictions, a methodology for tight coupling between an unstructured CFD solver and a computational structural dynamics tool was developed. Due to the lack of experimental data pertaining to a flexible turbine, the coupling algorithm was validated for a helicopter rotor, but the method is sufficiently general that it can be immediately applied to a wind turbine when suitable correlation data becomes available in the future. Finally, time-accurate overset rotor simulations of a complete turbine---blades, nacelle, and tower---were conducted using both RANS and HRLES turbulence models. The HRLES model was able to accurately predict rotor loads when stalled. In yawed flow, excellent correlations of mean blade loads with experimental data were obtained across the span, and wake asymmetry and unsteadiness were also well-predicted.

Lynch, C. Eric

2011-12-01

258

Wind Turbine Control for Load Reduction  

NASA Astrophysics Data System (ADS)

This article reviews techniques for the control of wind turbines during power production. Pitch control is used primarily to limit power in high winds, but it also has an important effect on structural loads. Particularly as turbines become larger, there is increasing interest in designing controllers to mitigate loads as far as possible. Torque control in variable-speed turbines is used primarily to maximize energy capture below rated wind speed, and to limit the torque above rated, but it can also be used to reduce certain loads. The design of the control algorithms is clearly of prime importance. Additional sensors such as accelerometers and load sensors can also help the controller to achieve its objectives more effectively. By controlling the pitch of each blade independently, it is also possible to achieve important further reductions in loading. It is important to be able to quantify the benefits of any new controller. Although computer simulations are useful, field trials are also vital. The variability of the real wind means that particular care is needed in the design of the trials.

Bossanyi, E. A.

2003-07-01

259

Mod-2 wind turbine system development. Volume 2: Detailed report  

NASA Technical Reports Server (NTRS)

Progress in the design, fabrication, and testing of a wind turbine system is reported. The development of the MOD-2 wind turbine through acceptance testing and initial operational evaluation is documented. The MOD-2 project intends to develop early commercialization of wind energy. The first wind turbine farm (three MOD-2 units) are now being operated at the Bonneville Power Administration site near Goldendale, Washington.

1982-01-01

260

A vertical-axis wind turbine  

NASA Astrophysics Data System (ADS)

Formulas are derived for the driving moment of a turbine rotor, which make it possible to determine the start-up torque for different blade profiles and arbitrary wind directions; this makes it possible to investigate the changing of angles of attack with the aim of attaining the highest start-up torque. Power, flow, and torque relationships are obtained, which can be used to determine required generator power curves. The solution of the equation of motion of the rotor makes it possible to investigate the time dependence of the kinematic variables and power. A design diagram is discussed, which can be used to determine the mean turbine-shaft horsepower as a function of shaft geometry and velocity, and wind velocity.

Slavik, S.

261

Baseline Design of a Hurricane-Resilient Wind Turbine (Poster)  

SciTech Connect

Under U.S. Department of Energy-sponsored research FOA 415, the National Renewable Energy Laboratory led a team of research groups to produce a complete design of a large wind turbine system to be deployable in the western Gulf of Mexico region. As such, the turbine and its support structure would be subjected to hurricane-loading conditions. Among the goals of this research was the exploration of advanced and innovative configurations that would help decrease the levelized cost of energy (LCOE) of the design, and the expansion of the basic IEC design load cases (DLCs) to include hurricane environmental conditions. The wind turbine chosen was a three-bladed, downwind, direct-drive, 10-MW rated machine. The rotor blade was optimized based on an IEC load suite analysis. The drivetrain and nacelle components were scaled up from a smaller sized turbine using industry best practices. The tubular steel tower was sized using ultimate load values derived from the rotor optimization analysis. The substructure is an innovative battered and raked jacket structure. The innovative turbine has also been modeled within an aero-servo-hydro-elastic tool, and future papers will discuss results of the dynamic response analysis for select DLCs. Although multiple design iterations could not be performed because of limited resources in this study, and are left to future research, the obtained data will offer a good indication of the expected LCOE for large offshore wind turbines to be deployed in subtropical U.S. waters, and the impact design innovations can have on this value.

Damiani, R.; Robertson, A.; Schreck, S.; Maples, B.; Anderson, M.; Finucane, Z.; Raina, A.

2014-10-01

262

Utility Scale Wind turbine Demonstration Project  

SciTech Connect

The purpose of the Three Affiliated Tribes proposing to Department of Energy was nothing new to Denmark. National Meteorological Studies have proved that North Dakota has some of the most consistence wind resources in the world. The Three Affiliated Tribes wanted to assess their potential and become knowledgeable to developing this new and upcoming resource now valuable. By the Tribe implementing the Utility-scale Wind Turbine Project on Fort Berthold, the tribe has proven the ability to complete a project, and has already proceeded in a feasibility studies to developing a large-scale wind farm on the reservation due to tribal knowledge learned, public awareness, and growing support of a Nation wanting clean renewable energy. The tribe is working through the various measures and regulations with the want to be self-sufficient, independent, and marketable with 17,000 times the wind energy needed to service Fort Berthold alone.

Terry Fredericks

2006-03-31

263

Development and testing of wavelet packet transform-based detector for ice accretion on wind turbines  

Microsoft Academic Search

This paper introduces a novel method for detecting ice accumulation on wind turbines. The proposed detection method is based on utilizing a multi-resolution analysis to extract specific frequency components present in the direct and quadrature components of the electric current flowing out of a wind generator. The basis of the proposed method lies in the fact that ice accumulation leads

S. A. Saleh; C. R. Moloney

2011-01-01

264

Wear Analysis of Wind Turbine Gearbox Bearings  

SciTech Connect

The objective of this effort was to investigate and characterize the nature of surface damage and wear to wind turbine gearbox bearings returned from service in the field. Bearings were supplied for examination by S. Butterfield and J. Johnson of the National Wind Technology Center (NREL), Boulder, Colorado. Studies consisted of visual examination, optical and electron microscopy, dimensional measurements of wear-induced macro-scale and micro-scale features, measurements of macro- and micro-scale hardness, 3D imaging of surface damage, studies of elemental distributions on fracture surfaces, and examinations of polished cross-sections of surfaces under various etched and non-etched conditions.

Blau, Peter Julian [ORNL; Walker, Larry R [ORNL; Xu, Hanbing [ORNL; Parten, Randy J [ORNL; Qu, Jun [ORNL; Geer, Tom [ORNL

2010-04-01

265

Root region airfoil for wind turbine  

DOEpatents

A thick airfoil is described for the root region of the blade of a wind turbine. The airfoil has a thickness in a range from 24%--26% and a Reynolds number in a range from 1,000,000 to 1,800,000. The airfoil has a maximum lift coefficient of 1.4--1.6 that has minimum sensitivity to roughness effects. 3 Figs.

Tangler, J.L.; Somers, D.M.

1995-05-23

266

Case Study #8: Wind Turbine Control Design  

Microsoft Academic Search

\\u000a In Chap. 13, HSSPFC is used to develop a new nonlinear\\/adaptive power flow control strategy for below-rated power control\\u000a of variable speed wind turbines. Fundamentally, the new controller is designed to optimize both stability and performance\\u000a criteria. Numerical results demonstrate that the nonlinear\\/adaptive power flow control increases efficiency, extracting more\\u000a power when compared to a conventional control strategy. In addition, the

Rush Robinett; David Wilson

267

Wind Turbine Generator System Duration Test Report for the Gaia-Wind 11 kW Wind Turbine  

SciTech Connect

This test was conducted as part of the U.S. Department of Energy's (DOE) Independent Testing project. This project was established to help reduce the barriers of wind energy expansion by providing independent testing results for small turbines. In total, five turbines are being tested at the National Renewable Energy Laboratory's (NRELs) National Wind Technology Center (NWTC) as a part of this project. Duration testing is one of up to five tests that may be performed on the turbines, including power performance, safety and function, noise, and power quality tests. The results of the testing will provide the manufacturers with reports that may be used for small wind turbine certification. The test equipment includes a Gaia-Wind 11 kW wind turbine mounted on an 18 m monopole tower. Gaia-Wind Ltd. manufactured the turbine in Denmark, although the company is based in Scotland. The system was installed by the NWTC Site Operations group with guidance and assistance from Gaia-Wind.

Huskey, A.; Bowen, A.; Jager, D.

2010-09-01

268

Flow separation on wind turbines blades  

NASA Astrophysics Data System (ADS)

In the year 2000, 15GW of wind power was installed throughout the world, producing 100PJ of energy annually. This contributes to the total electricity demand by only 0.2%. Both the installed power and the generated energy are increasing by 30% per year world-wide. If the airflow over wind turbine blades could be controlled fully, the generation efficiency and thus the energy production would increase by 9%. Power Control To avoid damage to wind turbines, they are cut out above 10 Beaufort (25 m/s) on the wind speed scale. A turbine could be designed in such a way that it converts as much power as possible in all wind speeds, but then it would have to be to heavy. The high costs of such a design would not be compensated by the extra production in high winds, since such winds are rare. Therefore turbines usually reach maximum power at a much lower wind speed: the rated wind speed, which occurs at about 6 Beaufort (12.5 m/s). Above this rated speed, the power intake is kept constant by a control mechanism. Two different mechanisms are commonly used. Active pitch control, where the blades pitch to vane if the turbine maximum is exceeded or, passive stall control, where the power control is an implicit property of the rotor. Stall Control The flow over airfoils is called "attached" when it flows over the surface from the leading edge to the trailing edge. However, when the angle of attack of the flow exceeds a certain critical angle, the flow does not reach the trailing edge, but leaves the surface at the separation line. Beyond this line the flow direction is reversed, i.e. it flows from the trailing edge backward to the separation line. A blade section extracts much less energy from the flow when it separates. This property is used for stall control. Stall controlled rotors always operate at a constant rotation speed. The angle of attack of the flow incident to the blades is determined by the blade speed and the wind speed. Since the latter is variable, it determines the angle of attack. The art of designing stall rotors is to make the separated area on the blades extend in such a way, that the extracted power remains precisely constant, independent of the wind speed, while the power in the wind at cut-out exceeds the maximum power of the turbine by a factor of 8. Since the stall behaviour is influenced by many parameters, this demand cannot be easily met. However, if it can be met, the advantage of stall control is its passive operation, which is reliable and cheap. Problem Definition In practical application, stall control is not very accurate and many stall-controlled turbines do not meet their specifications. Deviations of the design-power in the order of tens of percent are regular. In the nineties, the aerodynamic research on these deviations focussed on: profile aerodynamics, computational fluid dynamics, rotational effects on separation and pressure measurements on test turbines. However, this did not adequately solve the actual problems with stall turbines. In this thesis, we therefore formulated the following as the essential question: "Does the separated blade area really extend with the wind speed, as we predict?" To find the answer a measurement technique was required, which 1) was applicable on large commercial wind turbines, 2) could follow the dynamic changes of the stall pattern, 3) was not influenced by the centrifugal force and 4) did not disturb the flow. Such a technique was not available, therefore we decided to develop it. Stall Flag Method For this method, a few hundred indicators are fixed to the rotor blades in a special pattern. These indicators, called "stall flags" are patented by the Netherlands Energy Research Foundation (ECN). They have a retro-reflective area which, depending on the flow direction, is or is not covered. A powerful light source in the field up to 500m behind the turbine illuminates the swept rotor area. The uncovered reflectors reflect the light to the source, where a digital video camera records the dynamic stall patterns. The images are analyse

Corten, G. P.

2001-01-01

269

Estimation of turbulence level and scale for wind turbine applications  

SciTech Connect

A simplified method is presented for estimating onsite turbulence variance within the wind turbine layer for horizontal wind speed. The method is based principally on estimating the probability distribution of wind speed and assigning a variance to each mean wind speed based on surface roughness estimates. The model is not proposed as an alternative to onsite measurement and analysis, but rather as an adjunct to such a program. A revision of the Kaimal neutral u-component spectrum is suggested to apply to the mix of the stabilities occurring during operational winds. Values of integral length scale calculated from data analysis are shown to contradict the length scale model implicit in turbulence power spectra. Also, these calculated values are shown to be extremely sensitive to the length of the time series and the detrending method used. The analysis and modeling are extended to the rotational frame of reference for a horizontal-axis wind turbine by modeling the ratios of harmonic spike variances (1P, 2P, etc.) in the rotational spectrum to the Eulerian turbulence variance. 15 refs., 11 figs., 3 tabs.

Powell, D.C.

1988-11-01

270

Reconstruction of effective wind speed for fixed-speed wind turbines based on frequency data fusion  

Microsoft Academic Search

The rotator of the wind turbine is subject to a spatially and temporally distributed wind field, the wind speed will vary significantly at different point over the blades plane. This makes a direct measurement of effective wind speed impossible. This paper analyzes the spectrum of the measurement of the anemometer and generator power of a wind turbine, and points out

Zhiqiang Xu; Mehrdad Ehsani

2010-01-01

271

Disturbance Accommodating Adaptive Control with Application to Wind Turbines  

NASA Technical Reports Server (NTRS)

Adaptive control techniques are well suited to applications that have unknown modeling parameters and poorly known operating conditions. Many physical systems experience external disturbances that are persistent or continually recurring. Flexible structures and systems with compliance between components often form a class of systems that fail to meet standard requirements for adaptive control. For these classes of systems, a residual mode filter can restore the ability of the adaptive controller to perform in a stable manner. New theory will be presented that enables adaptive control with accommodation of persistent disturbances using residual mode filters. After a short introduction to some of the control challenges of large utility-scale wind turbines, this theory will be applied to a high-fidelity simulation of a wind turbine.

Frost, Susan

2012-01-01

272

Siting guidelines for utility application of wind turbines. Final report  

SciTech Connect

Utility-oriented guidelines are described for identifying viable sites for wind turbines. Topics and procedures are also discussed that are important in carrying out a wind turbine siting program. These topics include: a description of the Department of Energy wind resource atlases; procedures for predicting wind turbine performance at potential sites; methods for analyzing wind turbine economics; procedures for estimating installation and maintenance costs; methods for anlayzing the distribution of wind resources over an area; and instrumentation for documenting wind behavior at potential sites. The procedure described is applicable to small and large utilities. Although the procedure was developed as a site-selection tool, it can also be used by a utility who wishes to estimate the potential for wind turbine penetration into its future generation mix.

Pennell, W.T.

1983-01-01

273

An overview of DOE's wind turbine development programs  

NASA Astrophysics Data System (ADS)

The development of technologically advanced, higher efficiency wind turbines continues to be a high priority of the US wind industry. The United States Department of Energy (DOE) is conducting and sponsoring a range of programs aimed at assisting the wind industry with system design, development, and testing. The overall goal is to develop systems that can compete with conventional electric generation at $0.05/kWh at 5.8 m/s (13 mph sites) by the mid-1990s, and with fossil-fuel-based generators $0.04/kWh at 5.8 m/s sites by the year 2000. These goals will be achieved through several programs. The Value Engineered Turbine (VET) Program will promote the rapid development of US capability to manufacture wind turbines to take advantage of near-term market opportunities. These value-engineered turbines will stem from units with known and well-documented records of performance. The Advanced Wind Turbine Program will assist US industry to develop and integrate advanced technologies into utility-grade wind turbines for the near term (1993-1995), and to develop a new generation of innovative turbines for the year 2000. The Utility Wind Turbine Performance Verification Program, a collaborative agreement between the Electric Power Research Institute (EPRI) and DOE, will deploy and evaluate commercial-prototype wind turbines in typical utility operating environments to provide a bridge from development programs currently under way to commercial purchases of utility-grade wind turbines.

Laxson, A. S.; Hock, S. M.; Musial, W. D.; Goldman, P. R.

1992-12-01

274

CFD-based design load analysis of 5MW offshore wind turbine  

NASA Astrophysics Data System (ADS)

The structure and aerodynamic loads acting on NREL 5MW reference wind turbine blade are calculated and analyzed based on advanced Computational Fluid Dynamics (CFD) and unsteady Blade Element Momentum (BEM). A detailed examination of the six force components has been carried out (three force components and three moment components). Structure load (gravity and inertia load) and aerodynamic load have been obtained by additional structural calculations (CFD or BEM, respectively,). In CFD method, the Reynolds Average Navier-Stokes approach was applied to solve the continuity equation of mass conservation and momentum balance so that the complex flow around wind turbines was modeled. Written in C programming language, a User Defined Function (UDF) code which defines transient velocity profile according to the Extreme Operating Gust condition was compiled into commercial FLUENT package. Furthermore, the unsteady BEM with 3D stall model has also adopted to investigate load components on wind turbine rotor. The present study introduces a comparison between advanced CFD and unsteady BEM for determining load on wind turbine rotor. Results indicate that there are good agreements between both present methods. It is importantly shown that six load components on wind turbine rotor is significant effect under Extreme Operating Gust (EOG) condition. Using advanced CFD and additional structural calculations, this study has succeeded to construct accuracy numerical methodology to estimate total load of wind turbine that compose of aerodynamic load and structure load.

Tran, T. T.; Ryu, G. J.; Kim, Y. H.; Kim, D. H.

2012-11-01

275

WindPACT Turbine Rotor Design Study: June 2000--June 2002 (Revised)  

SciTech Connect

This report presents the results of the turbine rotor study completed by Global Energy Concepts (GEC) as part of the U.S. Department of Energy's WindPACT (Wind Partnership for Advanced Component Technologies) project. The purpose of the WindPACT project is to identify technology improvements that will enable the cost of energy from wind turbines to fall to a target of 3.0 cents/kilowatt-hour in low wind speed sites. The study focused on different rotor configurations and the effect of scale on those rotors.

Malcolm, D. J.; Hansen, A. C.

2006-04-01

276

DOE/NASA Mod-0A wind turbine performance  

NASA Technical Reports Server (NTRS)

Design and operation of a large wind turbine at Clayton, New Mexico is reported. This is the first of three identical 200 kW wind turbines to be operated on electric utility networks. A comparison between its predicted and measured power versus wind speed performance is presented.

Richards, T. R.; Neustadter, H. E.

1978-01-01

277

Extreme Loads for an Offshore Wind Turbine using Statistical  

E-print Network

Extreme Loads for an Offshore Wind Turbine using Statistical Extrapolation from Limited Field Data,itiscommontoeithercarry out extensive simulation studies or undertake a field measurement campaign. At the Blyth offshore wind here is to estimate extreme loads for an offshore wind turbine for which the environmental and load

Manuel, Lance

278

Wave Models for Offshore Wind Turbines Puneet Agarwal  

E-print Network

Wave Models for Offshore Wind Turbines Puneet Agarwal§ and Lance Manuely Department of Civil. These wave modeling assumptions do not adequately represent waves in shallow waters where most offshore wind for estimating loads on the support structure (monopile) of an offshore wind turbine. We use a 5MW utility

Manuel, Lance

279

Offshore Series Wind Turbine Variable Hub heights & rotor diameters  

E-print Network

3.6MW Offshore Series Wind Turbine GE Energy #12;Feature Variable Hub heights & rotor diameters-savings feature, considering the rigors of offshore power generation. The 3.6 MW offshore wind turbine also, for both on and offshore use. Special features include... As the world's first commercially available wind

Firestone, Jeremy

280

Dynamic wind turbine models in power system simulation tool  

E-print Network

Dynamic wind turbine models in power system simulation tool DIgSILENT Anca D. Hansen, Florin Iov models in power system simulation tool DIgSILENT Department: Wind Energy Department Risø-R-1400(ed.2)(EN system simulation tool PowerFactory DIgSILENT for different wind turbine concepts. It is the second

281

Cambridge Danehy Park Wind Turbine Preliminary Project Assessment  

E-print Network

Cambridge Danehy Park Wind Turbine Preliminary Project Assessment Overview MIT Wind Energy Projects in Action (WEPA) Project Team: Cy Chan, Pamela Silva, Chao Zhang Wind Resource Assessment Environmental Impact Community Impact Financial Analysis Turbine Evaluation Set For the full report, please visit: http

282

Power curve control in micro wind turbine design  

Microsoft Academic Search

In this work, a micro wind turbine will be designed and built for a series of wind tunnel tests (rotor dynamics and Wind Turbine (WT) start-up velocity). Its design stems from an original numerical code, developed by the authors, based on the Blade Element Momentum (BEM) Theory.From classic design criteria, having evaluated all the geometric characteristics, an innovative methodology will

R. Lanzafame; M. Messina

2010-01-01

283

Wind turbine design codes: A comparison of the structural response  

Microsoft Academic Search

The National Wind Technology Center (NWTC) of the National Renewable Energy Laboratory is continuing a comparison of several computer codes used in the design and analysis of wind turbines. The second part of this comparison determined how well the programs predict the structural response of wind turbines. In this paper, the authors compare the structural response for four programs: ADAMS,

M. L. Jr. Buhl; A. D. Wright; K. G. Pierce

2000-01-01

284

Advanced wind turbine design studies: Advanced conceptual study. Final report  

Microsoft Academic Search

In conjunction with the US Department of Energy and the National Renewable Energy Laboratory`s Advanced Wind Turbine Program, the Atlantic Orient Corporation developed preliminary designs for the next generation of wind turbines. These 50 kW and 350 kW turbines are based upon the concept of simplicity. By adhering to a design philosophy that emphasizes simplicity, we project that these turbines

P. Hughes; R. Sherwin

1994-01-01

285

Fatigue life variability and reliability analysis of a wind turbine blade  

NASA Astrophysics Data System (ADS)

Wind turbines must withstand harsh environments that induce many stress cycles into their components. A numerical analysis package is used to illustrate the sobering variability in predicted fatigue life with relatively small changes in inputs. The variability of the input parameters is modeled to obtain estimates of the fatigue reliability of the turbine blades.

Veers, P. S.; Sutherland, H. J.; Ashwill, T. D.

286

Radar-cross-section reduction of wind turbines. part 1.  

SciTech Connect

In recent years, increasing deployment of large wind-turbine farms has become an issue of growing concern for the radar community. The large radar cross section (RCS) presented by wind turbines interferes with radar operation, and the Doppler shift caused by blade rotation causes problems identifying and tracking moving targets. Each new wind-turbine farm installation must be carefully evaluated for potential disruption of radar operation for air defense, air traffic control, weather sensing, and other applications. Several approaches currently exist to minimize conflict between wind-turbine farms and radar installations, including procedural adjustments, radar upgrades, and proper choice of low-impact wind-farm sites, but each has problems with limited effectiveness or prohibitive cost. An alternative approach, heretofore not technically feasible, is to reduce the RCS of wind turbines to the extent that they can be installed near existing radar installations. This report summarizes efforts to reduce wind-turbine RCS, with a particular emphasis on the blades. The report begins with a survey of the wind-turbine RCS-reduction literature to establish a baseline for comparison. The following topics are then addressed: electromagnetic model development and validation, novel material development, integration into wind-turbine fabrication processes, integrated-absorber design, and wind-turbine RCS modeling. Related topics of interest, including alternative mitigation techniques (procedural, at-the-radar, etc.), an introduction to RCS and electromagnetic scattering, and RCS-reduction modeling techniques, can be found in a previous report.

Brock, Billy C.; Loui, Hung; McDonald, Jacob J.; Paquette, Joshua A.; Calkins, David A.; Miller, William K.; Allen, Steven E.; Clem, Paul Gilbert; Patitz, Ward E.

2012-03-05

287

Remote monitoring and nondestructive evaluation of wind turbine towers  

NASA Astrophysics Data System (ADS)

Wind turbine towers are in need of condition monitoring so as to lower the cost of unexpected maintenance. Wind loading from turbulence and gusts can cause damage in horizontal axis wind turbines even the supporting towers. Monitoring of wind turbines in service using embedded data sensor arrays usually is not targeted at the turbine-tower interaction from the perspective of structural dynamics. In this study the remote monitoring of the tower supporting a horizontal-axis wind turbine was attempted using a microwave interferometer. The dominant frequency of one tower was found to be decreased by more than 20% in 16 months. Numerical modeling using spectral finite elements is in progress and should provide further information regarding frequency shift due to stiffness variation and added mass. Expected outcome will contribute to remote monitoring procedures and nondestructive evaluation techniques for local wind turbine structures during operation.

Chiang, Chih-Hung; Yu, Chih-Peng; Hsu, Keng-Tsang; Cheng, Chia-Chi; Ke, Ying-Tzu; Shih, Yi-Ru

2014-03-01

288

Recent results from data analysis of dynamic stall on wind turbine blades  

SciTech Connect

Wind turbines are subjected to dynamic loading from a variety of different sources. Wind shear and turbulence cause time-varying inflow that results in unsteady airloads. Tower shadow, upwind turbine wakes, and yaw angles also introduce unsteady inflow to wind turbine rotors. Wind turbine designers must predict these loads accurately in order to adequately design blades, hubs, and the remaining support structure to achieve a 30-year life. Structural analysts have not been able to predict mean or dynamic loads accurately enough to predict the fatigue life of major wind turbine components with confidence. Part of the problem is due to uncertainty in the stochastic wind environments as mentioned earlier. Another important part of the problem is the lack of basic knowledge of rotary wing airfoil stall performance. There is mounting evidence that dynamic stall may be related to dynamic loads that are greater than predictions. This paper describes some results of investigations of unsteady aerodynamic loads measured on a wind turbine blade. The objective of the investigation is to understand the steady and unsteady stall behavior of wind turbine blades. 13 refs.

Butterfield, C P; Simms, D [National Renewable Energy Lab., Golden, CO (United States); Huyer, S [Colorado Univ., Boulder, CO (United States)

1992-01-01

289

Wind turbine inspection tests at UCSD  

NASA Astrophysics Data System (ADS)

The wind energy industry is rapidly growing in order to meet the increasing world energy demands as well as the need for clean and renewable energy sources. With the goal to explore new technologies and innovations which could help potentially improve the efficiency and effectiveness of wind energy, the NDE/SHM laboratory at UCSD acquired a unique wind turbine blade that will be used for performing several research projects related to wind turbine blade technology and non-destructive inspection techniques. The blade was built using the CX-100 design developed by TPI Composites, Inc. and Sandia National Laboratory (SNL). The 9-m blade was constructed with several embedded defects that represent the most common manufacturing defects typically found, such as out-of-plane waviness, composite delamination, and adhesive disbond. The defects were embedded during the manufacturing process by using similar methods developed by both TPI and SNL for simulating actual defect characteristics. Though the blade is small in comparison to the average utility sized blade of around 40 meters, the blade features similar materials and manufacturing methods, allowing for several inspections techniques to be studied on a representative platform. The inspection techniques include advanced infrared thermography and other guided wave techniques.

Tippmann, Jeffery D.; Manohar, Arun; Lanza di Scalea, Francesco

2012-04-01

290

Wind flow characteristics in the wakes of large wind turbines. Volume 1: Analytical model development  

NASA Technical Reports Server (NTRS)

A computer program to calculate the wake downwind of a wind turbine was developed. Turbine wake characteristics are useful for determining optimum arrays for wind turbine farms. The analytical model is based on the characteristics of a turbulent coflowing jet with modification for the effects of atmospheric turbulence. The program calculates overall wake characteristics, wind profiles, and power recovery for a wind turbine directly in the wake of another turbine, as functions of distance downwind of the turbine. The calculation procedure is described in detail, and sample results are presented to illustrate the general behavior of the wake and the effects of principal input parameters.

Eberle, W. R.

1981-01-01

291

Matching wind turbine rotors and loads: Computational methods for designers  

NASA Astrophysics Data System (ADS)

A comprehensive method for matching wind energy conversion system (WECS) rotors with the load characteristics of common electrical and mechanical applications was reported. A method was developed to convert the data into useful results: (1) from turbine efficiency and load torque characteristics, turbine power is predicted as a function of windspeed; (2) it is decided how turbine power is to be governed to insure safety of all components; (3) mechanical conversion efficiency comes into play to predict how useful delivered power varies with windspeed; (4) wind statistics are used to predict longterm energy output. Most systems are approximated by a graph and calculator approach. The method leads to energy predictions, and to insight into modeled processes. A computer program provides more sophisticated calculations where a highly unusual system is to be modeled, where accuracy is at a premium, or where error analysis is required. The analysis is fleshed out with in depth case studies for induction generator and inverter utility systems; battery chargers; resistance heaters; positive displacement pumps; including three different load compensation strategies; and centrifugal pumps with unregulated electric power transmission from turbine to pump.

Seale, J. B.

1983-04-01

292

Development of Fully Coupled Aeroelastic and Hydrodynamic Models for Offshore Wind Turbines: Preprint  

SciTech Connect

Aeroelastic simulation tools are routinely used to design and analyze onshore wind turbines, in order to obtain cost effective machines that achieve favorable performance while maintaining structural integrity. These tools employ sophisticated models of wind-inflow; aerodynamic, gravitational, and inertial loading of the rotor, nacelle, and tower; elastic effects within and between components; and mechanical actuation and electrical responses of the generator and of control and protection systems. For offshore wind turbines, additional models of the hydrodynamic loading in regular and irregular seas, the dynamic coupling between the support platform motions and wind turbine motions, and the dynamic characterization of mooring systems for compliant floating platforms are also important. Hydrodynamic loading includes contributions from hydrostatics, wave radiation, and wave scattering, including free surface memory effects. The integration of all of these models into comprehensive simulation tools, capable of modeling the fully coupled aeroelastic and hydrodynamic responses of floating offshore wind turbines, is presented.

Jonkman, J. M.; Sclavounos, P. D.

2006-01-01

293

An examination of loads and responses of a wind turbine undergoing variable-speed operation  

SciTech Connect

The National Renewable Energy Laboratory has recently developed the ability to predict turbine loads and responses for machines undergoing variable-speed operation. The wind industry has debated the potential benefits of operating wind turbine sat variable speeds for some time. Turbine system dynamic responses (structural response, resonance, and component interactions) are an important consideration for variable-speed operation of wind turbines. The authors have implemented simple, variable-speed control algorithms for both the FAST and ADAMS dynamics codes. The control algorithm is a simple one, allowing the turbine to track the optimum power coefficient (C{sub p}). The objective of this paper is to show turbine loads and responses for a particular two-bladed, teetering-hub, downwind turbine undergoing variable-speed operation. The authors examined the response of the machine to various turbulent wind inflow conditions. In addition, they compare the structural responses under fixed-speed and variable-speed operation. For this paper, they restrict their comparisons to those wind-speed ranges for which limiting power by some additional control strategy (blade pitch or aileron control, for example) is not necessary. The objective here is to develop a basic understanding of the differences in loads and responses between the fixed-speed and variable-speed operation of this wind turbine configuration.

Wright, A.D.; Buhl, M.L. Jr.; Bir, G.S.

1996-11-01

294

NREL Establishes a 1.5-MW Wind Turbine Test Platform for Research Partnerships (Fact Sheet)  

SciTech Connect

Research turbine supports sustained technology development. For more than three decades, engineers at the National Renewable Energy Laboratory's (NREL) National Wind Technology Center (NWTC) have worked with the U.S. Department of Energy (DOE) Wind Program and industry partners to advance wind energy technology, improve wind turbine performance, and reduce the cost of energy. Although there have been dramatic increases in performance and drops in the cost of wind energy-from $0.80 per kilowatt-hour to between $0.06 and $0.08 per kilowatt-hour-the goal of the DOE Wind Program is to further increase performance and reduce the cost of energy for land-based systems so that wind energy can compete with natural gas by 2020. In support of the program's research and development (R and D) efforts, NREL has constructed state-of-the-art facilities at the NWTC where industry partners, universities, and other DOE laboratories can conduct tests and experiments to further advance wind technology. The latest facility to come online is the DOE-GE 1.5-MW wind turbine test platform. Working with DOE, NREL purchased and installed a GE 1.5-MW wind turbine at the NWTC in 2009. Since then, NREL engineers have extensively instrumented the machine, conducted power performance and full-system modal tests, and collected structural loads measurements to obtain baseline characterization of the turbine's power curve, vibration characteristics, and fatigue loads in the uniquely challenging NWTC inflow environment. By successfully completing a baseline for the turbine's performance and structural response, NREL engineers have established a test platform that can be used by industry, university, and DOE laboratory researchers to test wind turbine control systems and components. The new test platform will also enable researchers to acquire the measurements needed to develop and validate wind turbine models and improve design codes.

Not Available

2012-03-01

295

RIS0-M-2432 SIMPLIFIED LAWS OF SIMIALRITY FOR WIND TURBINE ROTORS  

E-print Network

turbine, in order to improve the machine, optimize or adapt it to another wind climate than originally operation. The optimization of a stall-regulated wind turbine to different wind climates by variation-SPEED OPERATION OF A WIND TURBINE 16 6. OPTIMIZATION OF A STALL-REGULATED WIND TURBINE TO DIFFERENT WIND CLIMATES

296

66 APRIL | 2010 The FuTure oF Wind Turbine  

E-print Network

66 APRIL | 2010 The FuTure oF Wind Turbine diagnosTics Wind energy is undergoing expansion in the form of large-scale wind farms, wind energy cooperatives, wind turbines owned by indi- vidual investors of errors encoun- tered by the system. Knowledge of wind turbine pa- rameters and their impact on turbine

Kusiak, Andrew

297

Actuator control of edgewise vibrations in wind turbine blades  

NASA Astrophysics Data System (ADS)

Edgewise vibrations with low aerodynamic damping are of particular concern in modern multi-megawatt wind turbines, as large amplitude cyclic oscillations may significantly shorten the life-time of wind turbine components, and even lead to structural damages or failures. In this paper, a new blade design with active controllers is proposed for controlling edgewise vibrations. The control is based on a pair of actuators/active tendons mounted inside each blade, allowing a variable control force to be applied in the edgewise direction. The control forces are appropriately manipulated according to a prescribed control law. A mathematical model of the wind turbine equipped with active controllers has been formulated using an Euler-Lagrangian approach. The model describes the dynamics of edgewise vibrations considering the aerodynamic properties of the blade, variable mass and stiffness per unit length and taking into account the effect of centrifugal stiffening, gravity and the interaction between the blades and the tower. Aerodynamic loads corresponding to a combination of steady wind including the wind shear and the effect of turbulence are computed by applying the modified Blade Element Momentum (BEM) theory. Multi-Blade Coordinate (MBC) transformation is applied to an edgewise reduced order model, leading to a linear time-invariant (LTI) representation of the dynamic model. The LTI description obtained is used for the design of the active control algorithm. Linear Quadratic (LQ) regulator designed for the MBC transformed system is compared with the control synthesis performed directly on an assumed nominal representation of the time-varying system. The LQ regulator is also compared against vibration control performance using Direct Velocity Feedback (DVF). Numerical simulations have been carried out using data from a 5-MW three-bladed Horizontal-Axis Wind Turbine (HAWT) model in order to study the effectiveness of the proposed active controlled blade design in reducing edgewise vibrations. Results show that the use of the proposed control scheme significantly improves the response of the blade and promising performances can be achieved. Furthermore, under the conditions considered in this study quantitative comparisons of the LQ-based control strategies reveal that there is a marginal improvement in the performances obtained by applying the MBC transformation on the time-varying edgewise vibration model of the wind turbine.

Staino, A.; Basu, B.; Nielsen, S. R. K.

2012-03-01

298

77 FR 32497 - Grant of Authority for Subzone Status; Mitsubishi Power Systems Americas, Inc. (Wind Turbine...  

Federal Register 2010, 2011, 2012, 2013

...Status; Mitsubishi Power Systems Americas, Inc. (Wind Turbine Nacelles...special-purpose subzone at the wind turbine nacelle...facility of Mitsubishi Power Systems Americas...manufacturing of wind turbine nacelles...at the Mitsubishi Power Systems...

2012-06-01

299

Assessment and Optimization of Lidar Measurement Availability for Wind Turbine Control: Preprint  

SciTech Connect

Turbine-mounted lidars provide preview measurements of the incoming wind field. By reducing loads on critical components and increasing the potential power extracted from the wind, the performance of wind turbine controllers can be improved [2]. As a result, integrating a light detection and ranging (lidar) system has the potential to lower the cost of wind energy. This paper presents an evaluation of turbine-mounted lidar availability. Availability is a metric which measures the proportion of time the lidar is producing controller-usable data, and is essential when a wind turbine controller relies on a lidar. To accomplish this, researchers from Avent Lidar Technology and the National Renewable Energy Laboratory first assessed and modeled the effect of extreme atmospheric events. This shows how a multirange lidar delivers measurements for a wide variety of conditions. Second, by using a theoretical approach and conducting an analysis of field feedback, we investigated the effects of the lidar setup on the wind turbine. This helps determine the optimal lidar mounting position at the back of the nacelle, and establishes a relationship between availability, turbine rpm, and lidar sampling time. Lastly, we considered the role of the wind field reconstruction strategies and the turbine controller on the definition and performance of a lidar's measurement availability.

Davoust, S.; Jehu, A.; Bouillet, M.; Bardon, M.; Vercherin, B.; Scholbrock, A.; Fleming, P.; Wright, A.

2014-05-01

300

Wind Turbine Generator System Power Performance Test Report for the Gaia-Wind 11-kW Wind Turbine  

SciTech Connect

This test was conducted as part of the U.S. Department of Energy's (DOE) Independent Testing project. It is a power performance test that the National Renewable Energy Laboratory (NREL) conducted on the Gaia-Wind 11-kW small wind turbine.

Huskey, A.; Bowen, A.; Jager, D.

2009-12-01

301

Wind turbines in icing conditions: performance and prediction  

NASA Astrophysics Data System (ADS)

Wind farms in cold climate regions have an estimated installed capacity of 3 GW which constantly increases, e.g., in Scandinavia, the Alpine region, and North America. One significant problem in cold climate regions is icing. Icing on wind turbines causes a variety of problems: reduction of power production, overloading due to delayed stall, increased fatigue of components and risk of ice throw. Thus, power forecasts considering icing are important to optimize performance and to minimize risks. The present study aims at investigating how well the effect of icing can be included in power predictions. Studies concentrate on in-cloud icing - the most frequent reason for atmospheric icing on structures in most countries. Wind power production is predicted using the weather forecast model WRF coupled with a Kalman filter and an icing algorithm. The icing algorithm calculates ice load based on temperature, wind, cloud and rain water content from the WRF results. In previous studies, the model system demonstrated the ability to predict icing events. Forecasts will be simulated for a test site in complex terrain in Switzerland. It consists of two wind turbines equipped with wind, temperature, humidity and longwave radiation sensors. Additional equipment with regard to icing are two webcams monitoring icing on blades and anemometers and an icing sensor. LIDAR measurements were carried out in January 2010 to measure an undisturbed vertical wind profile. During winter 2009/2010 longer icing periods of a total length of 9 days and several shorter icing periods were observed. These icing events are used to evaluate the wind power forecasts under icing conditions.

Dierer, S.; Oechslin, R.; Cattin, R.

2010-09-01

302

Rotationally sampled wind characteristics and correlations with MOD-OA wind turbine response  

SciTech Connect

This report presents results of a comprehensive wind and wind turbine measurement program: the Clayton, New Mexico, vertical plane array/MOD-OA project. In this experiment, the turbulent wind was measured for a large array of fixed anemometers located two blade diameters upwind of a 200-kW horizontal-axis wind turbine (HAWT). Simultaneously, key wind turbine response parameters were also measured. The first of two major objectives of this experiment was to determine the turbulent wind, rotationally sampled to emulate the motion of the wind turbine blade, for the range of different wind speeds and stability classes actually experienced by the wind turbine. The second major objective was to correlate this rotationally sampled wind with the wind turbine blade stress and power, in order to assess the usefulness of the wind measurements for wind turbine loads testing a prediction. Time series of rotationally sampled winds and wind turbine blade bending moments and power were converted to frequency spectra using Fourier transform techniques. These spectra were used as the basis for both qualitative and quantitative comparisons among the various cases. A quantitative comparison between the rotationally sampled wind input and blade bending response was made, using the Fourier spectra to estimate the blade transfer function. These transfer functions were then used to calculate an approximate damping coefficient for the MOD-OA fiberglass blade.

George, R.L.; Connell, J.R.

1984-09-01

303

Chances in wind energy: a probalistic approach to wind turbine fatigue design  

Microsoft Academic Search

Wind is becoming an ever more important source of renewable energy: installed wind turbine power now stands at 60,000 MW worldwide, providing 0.6% of world electricity demand. Still it is important that the cost of wind energy is brought down further, which means that wind turbines must be designed to be exactly as strong as necessary, but no stronger. Hence

Herman Frederik Veldkamp

2006-01-01

304

Wind Turbines Make Waves: Why Some Residents near Wind Turbines Become Ill  

ERIC Educational Resources Information Center

People who live near wind turbines complain of symptoms that include some combination of the following: difficulty sleeping, fatigue, depression, irritability, aggressiveness, cognitive dysfunction, chest pain/pressure, headaches, joint pain, skin irritations, nausea, dizziness, tinnitus, and stress. These symptoms have been attributed to the…

Havas, Magda; Colling, David

2011-01-01

305

Multi-piece wind turbine rotor blades and wind turbines incorporating same  

DOEpatents

A multisection blade for a wind turbine includes a hub extender having a pitch bearing at one end, a skirt or fairing having a hole therethrough and configured to mount over the hub extender, and an outboard section configured to couple to the pitch bearing.

Moroz; Emilian Mieczyslaw (San Diego, CA) [San Diego, CA

2008-06-03

306

NREL Software Aids Offshore Wind Turbine Designs (Fact Sheet)  

SciTech Connect

NREL researchers are supporting offshore wind power development with computer models that allow detailed analyses of both fixed and floating offshore wind turbines. While existing computer-aided engineering (CAE) models can simulate the conditions and stresses that a land-based wind turbine experiences over its lifetime, offshore turbines require the additional considerations of variations in water depth, soil type, and wind and wave severity, which also necessitate the use of a variety of support-structure types. NREL's core wind CAE tool, FAST, models the additional effects of incident waves, sea currents, and the foundation dynamics of the support structures.

Not Available

2013-10-01

307

Preliminary results of the large experimental wind turbine phase of the national wind energy program  

NASA Technical Reports Server (NTRS)

The preliminary results of two projects in the development phase of reliable wind turbines designed to supply cost-competitive electrical energy were discussed. An experimental 100 kW wind turbine design and its status are first reviewed. The results of two parallel design studies for determining the configurations and power levels for wind turbines with minimum energy costs are also discussed. These studies predict wind energy costs of 1.5 to 7 cents per kW-h for wind turbines produced in quantities of 100 to 1000 per year and located at sites having average winds of 12 to 18 mph.

Thomas, R. L.; Sholes, T.; Sholes, J. E.

1975-01-01

308

VDMA Forschungsprojekt: Ermittlung von Ermüdungslasten an großen Windenergieanlagen VDMA Research Project: Monitoring Fatigue Loads at Large Wind Turbines  

Microsoft Academic Search

SUMMARY Wind turbines show a potential for enhanced economy with growing size. Exploiting this potential forces engineers to design wind turbine components closer to their limits. At the same time the present level of safety must be maintained. However, in practice the fatigue community has not quite cut the edge of the problem how to estimate fatigue loads con- servative

Henry Seifert

309

Controlled Velocity Testing of an 8-kW Wind Turbine  

SciTech Connect

This paper describes a case study of the controlled-velocity test of an 8-kW wind turbine. The turbine was developed in response to the U.S. Department of Energy's small wind turbine program. As background, the prototype development is discussed. The turbine mechanical and electrical components are described. The turbine was tested on a flatbed truck and driven down an airfield runway at constant relative wind speed. Horizontal furling was used to control over-speed. Various parameters were changed to determine their effects on furling. The testing showed that the machine had insufficient rotor offset for adequate furling. Also, a rotor resonance problem was discovered and remedied. Problems associated with taking the measurements made it difficult to determine if the truck test was a suitable method for code validation. However, qualitative observations gleaned from the testing justified the effort.

Larwood, S.; Sencenbaugh, J.; Acker, B.

2001-07-31

310

Wind tunnel simulation of a wind turbine wake in neutral, stable and unstable wind flow  

NASA Astrophysics Data System (ADS)

Measurements of mean velocity, Reynolds stresses, temperature and heat flux have been made in the wake of a model wind turbine in the EnFlo meteorology wind tunnel, for three atmospheric boundary layer states: the base-line neutral case, stable and unstable. The full-to-model scale is approximately 300:1. Primary instrumentation is two-component LDA combine with cold-wire thermometry to measure heat flux. In terms of surface conditions, the stratified cases are weak, but there is a strong 'imposed' condition in the stable case. The measurements were made between 0.5D and 10D, where D is the turbine disk diameter. In the stable case the velocity deficit decreases more slowly; more quickly in the unstable case. Heights at which quantities are maximum or minimum are greater in the unstable case and smaller in the stable case. In the stable case the wake height is suppressed but the width is increased, while in the unstable case the height is increased and the width (at hub height) reaches a maximum and then decreases. The turbulence in the wake behaves in a complex way. Further work needs to be done, to cover stronger levels of surface condition, requiring more extensive measurements to properly capture the wake development.

Hancock, P. E.; Zhang, S.; Pascheke, F.; Hayden, P.

2014-12-01

311

Turbulence within variable-size wind turbine arrays  

NASA Astrophysics Data System (ADS)

A wind tunnel experiment was performed to study turbulence processes within a model wind turbine array of 3 by 8 model wind turbines of alternating sizes placed aligned with the mean flow. The model wind farm was placed in a boundary layer developed over both smooth and rough surfaces under neutrally stratified conditions. Turbulence statistics, TKE budget terms, and the spectral structure of the turbulence generated within and above the wind farm reveal relevant information about the processes modulating the turbulent energy transfer from the boundary layer to the turbines. The results of the experiment suggest that heterogeneity in turbine size within a wind farm introduce complex flow interactions not seen in a homogeneous farm, and may have positive effects on turbulent loading on the turbines and turbulent exchange with the atmosphere. In general, large scale motions are heavily dampened behind the first row of turbines but a portion of such structures are generated far inside the wind farm, and the scale of the most energetic eddy motions was relatively consistent at different elevations. Overall, the experiment revealed the possibility that heterogeneity of wind turbine size within wind farms have the potential to change the overall potential to harvest energy from the wind, and alter the economics of a project.

Chamorro, L. P.; Arndt, R. E. A.; Sotiropoulos, F.

2014-12-01

312

Fluid-Structure Interaction Analysis of Wind Turbines  

NASA Astrophysics Data System (ADS)

Countries around the world are putting substantial effort into the development of wind energy technologies. The urgent need of renewable energy puts pressure on the wind energy industry research and development to enhance the current wind generation capabilities and decrease the associated costs. Currently most wind turbine aerodynamics and aeroelasticity simulations are performed using low-fidelity methods. These methods are simple to implement and fast to execute; however, the cases involving important features, such as unsteady flow, turbulence, and details of the wind turbine geometry, are beyond their range of applicability. In this dissertation, we introduce a paradigm shift in wind turbine analysis by developing 3D, complex geometry, time-dependent, multi-physics modeling procedures for wind turbine fluid-structure interaction (FSI). The proposed framework consists of a collection of numerical methods combined into a single framework for FSI modeling and simulation of wind turbines at full scale. The use of the Navier-Stokes equations of incompressible flows for wind turbine aerodynamics is validated against experimental data. The structural modeling of the composite blades is based on the Kirchhoff-Love thin shell theory discretized using isogeometric analysis. The coupled FSI formulation is derived using the augmented Lagrangian approach and accommodates non-matching fluid-structure interface discretizations. The challenges of fluid-structural coupling and the handling of computational domains in relative motion are discussed, and the FSI computations of a 5 MW offshore baseline wind turbine are shown.

Hsu, Ming-Chen

313

Passive load control for large wind turbines.  

SciTech Connect

Wind energy research activities at Sandia National Laboratories focus on developing large rotors that are lighter and more cost-effective than those designed with current technologies. Because gravity scales as the cube of the blade length, gravity loads become a constraining design factor for very large blades. Efforts to passively reduce turbulent loading has shown significant potential to reduce blade weight and capture more energy. Research in passive load reduction for wind turbines began at Sandia in the late 1990's and has moved from analytical studies to blade applications. This paper discusses the test results of two Sandia prototype research blades that incorporate load reduction techniques. The TX-100 is a 9-m long blade that induces bend-twist coupling with the use of off-axis carbon in the skin. The STAR blade is a 27-m long blade that induces bend-twist coupling by sweeping the blade in a geometric fashion.

Ashwill, Thomas D.

2010-05-01

314

Wind turbine generator with improved operating subassemblies  

DOEpatents

A wind turbine includes a yaw spring return assembly to return the nacelle from a position to which it has been rotated by yawing forces, thus preventing excessive twisting of the power cables and control cables. It also includes negative coning restrainers to limit the bending of the flexible arms of the rotor towards the tower, and stop means on the rotor shaft to orient the blades in a vertical position during periods when the unit is upwind when the wind commences. A pendulum pitch control mechanism is improved by orienting the pivot axis for the pendulum arm at an angle to the longitudinal axis of its support arm, and excessive creep is of the synthetic resin flexible beam support for the blades is prevented by a restraining cable which limits the extent of pivoting of the pendulum during normal operation but which will permit further pivoting under abnormal conditions to cause the rotor to stall.

Cheney, Jr., Marvin C. (24 Stonepost Rd., Glastonbury, CT 06033)

1985-01-01

315

(Construction of a wind turbine). Final report  

SciTech Connect

A wind powered electrical generator was built by industrial arts students working in electricity, woodworking, and metal technology facilities. The blades were originally aluminum frames covered with sailcloth. These were replaced with hand-carved laminated basswood blades. Original plans called for a bullet and downwind propeller, but this was replaced with an upwind propeller and an aft-mounted tailfin. A V-belt and pulley drive transmits power from the turbine and a motorcycle brake stops the machine during high winds and/or for safe servicing. The original 13 volt, 105 amp alternator was replaced by a 12 volt, 100 amp dc generator. Publicity and dissemination events are listed as well as expenditures. (LEW)

Devine, L.E.

1982-03-22

316

Control of Wind Turbines: Past, Present, and Future  

SciTech Connect

We review the objectives and techniques used in the control of horizontal axis wind turbines at the individual turbine level, where controls are applied to the turbine blade pitch and generator. The turbine system is modeled as a flexible structure operating in the presence of turbulent wind disturbances. Some overview of the various stages of turbine operation and control strategies used to maximize energy capture in below rated wind speeds is given, but emphasis is on control to alleviate loads when the turbine is operating at maximum power. After reviewing basic turbine control objectives, we provide an overview of the common basic linear control approaches and then describe more advanced control architectures and why they may provide significant advantages.

Laks, J. H.; Pao, L. Y.; Wright, A. D.

2009-01-01

317

LIGHTNING EXPOSURE OF WIND TURBINES University of Toronto  

E-print Network

LIGHTNING EXPOSURE OF WIND TURBINES Dale Dolan University of Toronto e-mail: dale@ecf.utoronto.ca Abstract This paper applies the electrogeometric model of lightning exposure to a wind turbine to compute its risk of damage due to a direct lightning strike in an area of known lightning flash density

Lehn, Peter W.

318

Wind turbine load reduction by rejecting the periodic load disturbances  

Microsoft Academic Search

For the cost per kilowatt hour to be decreased, the trend in offshore wind turbines is to increase the rotor diameter as much as possible. The increasing dimensions have led to a relative increase of the loads on the wind turbine structure; thus, it is necessary to react to disturbances in a more detailed way, e.g. each blade separately. The

I. Houtzager; Jan-Willem van Wingerden; Michel Verhaegen

2012-01-01

319

Wind turbines emulating inertia and supporting primary frequency control  

Microsoft Academic Search

The increasing penetration of variable-speed wind turbines in the electricity grid will result in a reduction of the number of connected conventional power plants. This will require changes in the way the grid frequency is controlled. In this letter, a method is proposed to let variable-speed wind turbines emulate inertia and support primary frequency control. The required power is obtained

Johan Morren; Sjoerd W. H. de Haan; Wil L. Kling; J. A. Ferreira

2006-01-01

320

General review of the MOSTAS computer code for wind turbines  

NASA Technical Reports Server (NTRS)

The MOSTAS computer code for wind turbine analysis is reviewed, and techniques and methods used in its analyses are described. Impressions of its strengths and weakness, and recommendations for its application, modification, and further development are made. Basic techniques used in wind turbine stability and response analyses for systems with constant and periodic coefficients are reviewed.

Dungundji, J.; Wendell, J. H.

1981-01-01

321

Combined high density solar panels and vertical wind turbines  

Microsoft Academic Search

The combined high density solar panels and vertical wind turbines consist of multiple solar panels with closely spaced solar cells on both sides which are supported by an open framework and vertical posts. The adoption of an elevated, rooftop solar panel array, supported by vertical posts makes the basic structure attractive for the inclusion of multiple vertical wind turbines, as

1978-01-01

322

Lightning protection for wind turbine blades and bearings  

Microsoft Academic Search

The protection of wind turbines from lightning damage is increasingly important as they increase in size and are placed in locations where access to carry out repairs may be difficult. As blades are the most common attachment point of lightning, they must be adequately protected. In addition, the passage of lightning current through wind turbine bearings introduces a risk of

Ian Cotton; Nick Jenkins; Krishnan Pandiaraj

2001-01-01

323

Full Scale Testing for Investigation of Wind Turbine Seismic Response  

Microsoft Academic Search

The earthquake response of wind turbines is a topic of interest, relevant to installations in seismic regions. In recent years, researchers and practitioners have approached this problem through application of existing code for building structures as well as numerical and analytical modeling of wind turbines. The Network for Earthquake Engineering Simulation Large High Performance Outdoor Shake Table at the University

Ian Prowell; Marc Veletzos; Ahmed Elgamal

324

Wind turbine design codes: A preliminary comparison of the aerodynamics  

Microsoft Academic Search

The National Wind Technology Center of the National Renewable Energy Laboratory is comparing several computer codes used to design and analyze wind turbines. The first part of this comparison is to determine how well the programs predict the aerodynamic behavior of turbines with no structural degrees of freedom. Without general agreement on the aerodynamics, it is futile to try to

Marshall L. Buhl; Alan D. Wright; James L. Tangler

1997-01-01

325

Using partial safety factors in wind turbine design and testing  

Microsoft Academic Search

This paper describes the relationship between wind turbine design and testing in terms of the certification process. An overview of the current status of international certification is given along with a description of limit-state design basics. Wind turbine rotor blades are used to illustrate the principles discussed. These concepts are related to both International Electrotechnical Commission and Germanischer Lloyd design

W. D. Musial; C. Butterfield

1997-01-01

326

DOE/NASA Lewis large wind turbine program  

NASA Technical Reports Server (NTRS)

An overview of the large wind turbine activities managed by NASA is given. These activities include resuls from the first and second generation field machines (Mod-0A, -1, and -2), the status of the Department of Interior WTS-4 machine for which NASA is responsible for technical management, and the design phase of the third generation wind turbines (Mod-5).

Thomas, R. L.

1982-01-01

327

DIRECT-COUPLED PERMANENT MAGNET WIND TURBINE DESIGN CONSIDERATIONS  

Microsoft Academic Search

The paper presents the design procedure of a permanent magnet generator for a 20 kW wind turbine prototype. This work has been developed in the frame of a research project funded by the General Secretariat for Research and Technology of Greece concerning the design and construction of a gear-less wind turbine for both autonomous and interconnected operation with the electrical

S. A. Papathanassiou; A. G. Kladas; M. P. Papadopoulos

328

Structural design and fabrication of the Sandia 34-meter Vertical Axis Wind Turbine  

NASA Astrophysics Data System (ADS)

The Wind Energy Research Division of Sandia National Laboratories has been funded by the Wind/Ocean Technology Division of the Department of Energy (DOE) to design and build a 34-meter diameter Vertical Axis Wind Turbine (VAWT). The turbine design incorporates the results of recent VAWT research in aerodynamics and structural dynamics. Initial system concept studies identified several blade options that met the required power rating of 500 kW. The final blade and rotor configurations were chosen based on finite element calculations that determined the turbine modes of response, their frequency of vibration, and stress levels. Parked survival turbine components were designed to withstand the loading of a 150 mph (67.0 m/s) wind coupled with maximum cable tensions. Specific areas of design discussed include the rotor, cables, bearings, brakes, and foundations.

Ashwill, T. D.

1987-01-01

329

Incorporating Irregular Nonlinear Waves in Coupled Simulation of Offshore Wind Turbines  

E-print Network

, and Environmental Engineering The University of Texas, Austin, TX 78712 Design of an offshore wind turbine requires for design of offshore wind turbines. Response of an offshore wind turbine to the input wind and waves, bothIncorporating Irregular Nonlinear Waves in Coupled Simulation of Offshore Wind Turbines Puneet

Manuel, Lance

330

innovati nNREL Innovations Contribute to an Award-Winning Small Wind Turbine  

E-print Network

blade design that makes the wind turbine more efficient and quieter than most. Small wind turbines is engineered to quietly and efficiently produce power from low-speed winds. The turbine was designedinnovati nNREL Innovations Contribute to an Award-Winning Small Wind Turbine The Skystream 3.7 wind

331

An Induction Motor Based Wind Turbine Emulator  

NASA Astrophysics Data System (ADS)

The authors present a small-scale wind turbine emulator based on the AC drive system and discuss the methods for power coefficient calculation. In the work, the experimental set-up consisting of an AC induction motor, a frequency converter, a synchronous permanent magnet generator, a DC-DC boost converter and DC load was simulated and tested using real-life equipment. The experimentally obtained wind turbine power and torque diagrams using the emulator are in a good agreement with the theoretical ones. Šaj? rakst? par?d?ta mazas jaudas v?ja turb?nas emulatora izveide ar mai?str?vas piedzi?as sist?mu, k? ar? analiz?tas vair?kas turb?nas jaudas koeficienta anal?tisk?s apr??ina metodes. V?ja turb?nas emulatora eksperiment?lais stends, kas sast?v no asinhron? elektromotora, frekven?u p?rveidot?ja, sinhron? past?v?go magn?tu ?eneratora, l?dzstr?vas paaugstinoš? p?rveidot?ja un slodzes, tika p?rbaud?ts gan simul?šanas vid?, gan uz re?l?m iek?rt?m. Eksperiment?li ieg?t?s v?ja turb?nas emulatora jaudas un momenta diagrammas ir sal?dzin?tas ar teor?tiskaj?m.

Sokolovs, A.; Grigans, L.; Kamolins, E.; Voitkans, J.

2014-04-01

332

Duration Test Report for the Ventera VT10 Wind Turbine  

SciTech Connect

This project was established to help reduce the barriers of wind energy expansion by providing independent testing results for small wind turbines. Five turbines were tested at the National Wind Technology Center (NWTC) at the National Renewable Energy Laboratory (NREL) as a part of round one of this project. Duration testing is one of up to five tests that may be performed on the turbines, including power performance, safety and function, noise, and power quality. Test results will provide manufacturers with reports that can be used to fulfill part of the requirements for small wind turbine certification. The test equipment included a grid-connected Ventera Energy Corporation VT10 wind turbine mounted on an 18.3-m (60-ft) self-supporting lattice tower manufactured by Rohn.

Smith, J.; Huskey, A.; Jager, D.; Hur, J.

2013-06-01

333

Wind turbine control applications of turbine-mounted LIDAR  

NASA Astrophysics Data System (ADS)

In recent years there has been much interest in the possible use of LIDAR systems for improving the performance of wind turbine controllers, by providing preview information about the approaching wind field. Various potential benefits have been suggested, and experimental measurements have sometimes been used to claim surprising gains in performance. This paper reports on an independent study which has used detailed analytical methods for two main purposes: firstly to try to evaluate the likely benefits of LIDAR-assisted control objectively, and secondly to provide advice to LIDAR manufacturers about the characteristics of LIDAR systems which are most likely to be of value for this application. Many different LIDAR configurations were compared: as a general conclusion, systems should be able to sample at least 10 points every second, reasonably distributed around the swept area, and allowing a look-ahead time of a few seconds. An important conclusion is that the main benefit of the LIDAR will be to enhance of collective pitch control to reduce thrust-related fatigue loads; there is some indication that extreme loads can also be reduced, but this depends on other considerations which are discussed in the paper. LIDAR-assisted individual pitch control, optimal Cp tracking and yaw control were also investigated, but the benefits over conventional methods are less clear.

Bossanyi, E. A.; Kumar, A.; Hugues-Salas, O.

2014-12-01

334

Atmospheric and Wake Turbulence Impacts on Wind Turbine Fatigue Loadings  

Microsoft Academic Search

Large-eddy simulations of atmospheric boundary layers under various stability and surface roughness conditions are performed to investigate the turbulence impact on wind turbines. In particular, the aeroelastic responses of the turbines are studied to characterize the fatigue loading of the turbulence present in the boundary layer and in the wake of the turbines. Two utility-scale 5-MW turbines that are separated

S. Lee; M. Churchfield; P. Moriarty; J. Jonkman; J. Michalakes

2012-01-01

335

CgWind: A high-order accurate simulation tool for wind turbines and wind farms  

SciTech Connect

CgWind is a high-fidelity large eddy simulation (LES) tool designed to meet the modeling needs of wind turbine and wind park engineers. This tool combines several advanced computational technologies in order to model accurately the complex and dynamic nature of wind energy applications. The composite grid approach provides high-quality structured grids for the efficient implementation of high-order accurate discretizations of the incompressible Navier-Stokes equations. Composite grids also provide a natural mechanism for modeling bodies in relative motion and complex geometry. Advanced algorithms such as matrix-free multigrid, compact discretizations and approximate factorization will allow CgWind to perform highly resolved calculations efficiently on a wide class of computing resources. Also in development are nonlinear LES subgrid-scale models required to simulate the many interacting scales present in large wind turbine applications. This paper outlines our approach, the current status of CgWind and future development plans.

Chand, K K; Henshaw, W D; Lundquist, K A; Singer, M A

2010-02-22

336

Atmospheric and Wake Turbulence Impacts on Wind Turbine Fatigue Loading: Preprint  

SciTech Connect

Large-eddy simulations of atmospheric boundary layers under various stability and surface roughness conditions are performed to investigate the turbulence impact on wind turbines. In particular, the aeroelastic responses of the turbines are studied to characterize the fatigue loading of the turbulence present in the boundary layer and in the wake of the turbines. Two utility-scale 5 MW turbines that are separated by seven rotor diameters are placed in a 3 km by 3 km by 1 km domain. They are subjected to atmospheric turbulent boundary layer flow and data is collected on the structural response of the turbine components. The surface roughness was found to increase the fatigue loads while the atmospheric instability had a small influence. Furthermore, the downstream turbines yielded higher fatigue loads indicating that the turbulent wakes generated from the upstream turbines have significant impact.

Lee, S.; Churchfield, M.; Moriarty, P.; Jonkman, J.; Michalakes, J.

2011-12-01

337

Annoyance, detection and recognition of wind turbine noise.  

PubMed

Annoyance, recognition and detection of noise from a single wind turbine were studied by means of a two-stage listening experiment with 50 participants with normal hearing abilities. In-situ recordings made at close distance from a 1.8-MW wind turbine operating at 22 rpm were mixed with road traffic noise, and processed to simulate indoor sound pressure levels at LAeq 40 dBA. In a first part, where people were unaware of the true purpose of the experiment, samples were played during a quiet leisure activity. Under these conditions, pure wind turbine noise gave very similar annoyance ratings as unmixed highway noise at the same equivalent level, while annoyance by local road traffic noise was significantly higher. In a second experiment, listeners were asked to identify the sample containing wind turbine noise in a paired comparison test. The detection limit of wind turbine noise in presence of highway noise was estimated to be as low as a signal-to-noise ratio of -23 dBA. When mixed with local road traffic, such a detection limit could not be determined. These findings support that noticing the sound could be an important aspect of wind turbine noise annoyance at the low equivalent levels typically observed indoors in practice. Participants that easily recognized wind-turbine(-like) sounds could detect wind turbine noise better when submersed in road traffic noise. Recognition of wind turbine sounds is also linked to higher annoyance. Awareness of the source is therefore a relevant aspect of wind turbine noise perception which is consistent with previous research. PMID:23624007

Van Renterghem, Timothy; Bockstael, Annelies; De Weirt, Valentine; Botteldooren, Dick

2013-07-01

338

ERCOT's Dynamic Model of Wind Turbine Generators: Preprint  

SciTech Connect

By the end of 2003, the total installed wind farm capacity in the Electric Reliability Council of Texas (ERCOT) system was approximately 1 gigawatt (GW) and the total in the United States was about 5 GW. As the number of wind turbines installed throughout the United States increases, there is a greater need for dynamic wind turbine generator models that can properly model entire power systems for different types of analysis. This paper describes the ERCOT dynamic models and simulations of a simple network with different types of wind turbine models currently available.

Muljadi, E.; Butterfield, C. P.; Conto, J.; Donoho, K.

2005-08-01

339

Using machine learning to predict wind turbine power output  

NASA Astrophysics Data System (ADS)

Wind turbine power output is known to be a strong function of wind speed, but is also affected by turbulence and shear. In this work, new aerostructural simulations of a generic 1.5 MW turbine are used to rank atmospheric influences on power output. Most significant is the hub height wind speed, followed by hub height turbulence intensity and then wind speed shear across the rotor disk. These simulation data are used to train regression trees that predict the turbine response for any combination of wind speed, turbulence intensity, and wind shear that might be expected at a turbine site. For a randomly selected atmospheric condition, the accuracy of the regression tree power predictions is three times higher than that from the traditional power curve methodology. The regression tree method can also be applied to turbine test data and used to predict turbine performance at a new site. No new data are required in comparison to the data that are usually collected for a wind resource assessment. Implementing the method requires turbine manufacturers to create a turbine regression tree model from test site data. Such an approach could significantly reduce bias in power predictions that arise because of the different turbulence and shear at the new site, compared to the test site.

Clifton, A.; Kilcher, L.; Lundquist, J. K.; Fleming, P.

2013-06-01

340

Model predictive control of a wind turbine modelled in Simpack  

NASA Astrophysics Data System (ADS)

Wind turbines (WT) are steadily growing in size to increase their power production, which also causes increasing loads acting on the turbine's components. At the same time large structures, such as the blades and the tower get more flexible. To minimize this impact, the classical control loops for keeping the power production in an optimum state are more and more extended by load alleviation strategies. These additional control loops can be unified by a multiple-input multiple-output (MIMO) controller to achieve better balancing of tuning parameters. An example for MIMO control, which has been paid more attention to recently by wind industry, is Model Predictive Control (MPC). In a MPC framework a simplified model of the WT is used to predict its controlled outputs. Based on a user-defined cost function an online optimization calculates the optimal control sequence. Thereby MPC can intrinsically incorporate constraints e.g. of actuators. Turbine models used for calculation within the MPC are typically simplified. For testing and verification usually multi body simulations, such as FAST, BLADED or FLEX5 are used to model system dynamics, but they are still limited in the number of degrees of freedom (DOF). Detailed information about load distribution (e.g. inside the gearbox) cannot be provided by such models. In this paper a Model Predictive Controller is presented and tested in a co-simulation with SlMPACK, a multi body system (MBS) simulation framework used for detailed load analysis. The analysis are performed on the basis of the IME6.0 MBS WT model, described in this paper. It is based on the rotor of the NREL 5MW WT and consists of a detailed representation of the drive train. This takes into account a flexible main shaft and its main bearings with a planetary gearbox, where all components are modelled flexible, as well as a supporting flexible main frame. The wind loads are simulated using the NREL AERODYN v13 code which has been implemented as a routine to SlMPACK. This modeling approach allows to investigate the nonlinear behavior of wind loads and nonlinear drive train dynamics. Thereby the MPC's impact on specific loads and effects not covered by standard simulation tools can be assessed and investigated. Keywords. wind turbine simulation, model predictive control, multi body simulation, MIMO, load alleviation

Jassmann, U.; Berroth, J.; Matzke, D.; Schelenz, R.; Reiter, M.; Jacobs, G.; Abel, D.

2014-06-01

341

Dissipation of Turbulence in the Wake of a Wind Turbine  

NASA Astrophysics Data System (ADS)

The wake of a wind turbine is characterized by increased turbulence and decreased wind speed. Turbines are generally deployed in large groups in wind farms, and so the behaviour of an individual wake as it merges with other wakes and propagates downwind is critical in assessing wind-farm power production. This evolution depends on the rate of turbulence dissipation in the wind-turbine wake, which has not been previously quantified in field-scale measurements. In situ measurements of winds and turbulence dissipation from the wake region of a multi-MW turbine were collected using a tethered lifting system (TLS) carrying a payload of high-rate turbulence probes. Ambient flow measurements were provided from sonic anemometers on a meteorological tower located near the turbine. Good agreement between the tower measurements and the TLS measurements was established for a case without a wind-turbine wake. When an operating wind turbine is located between the tower and the TLS so that the wake propagates to the TLS, the TLS measures dissipation rates one to two orders of magnitude higher in the wake than outside of the wake. These data, collected between two and three rotor diameters downwind of the turbine, document the significant enhancement of turbulent kinetic energy dissipation rate within the wind-turbine wake. These wake measurements suggest that it may be useful to pursue modelling approaches that account for enhanced dissipation. Comparisons of wake and non-wake dissipation rates to mean wind speed, wind-speed variance, and turbulence intensity are presented to facilitate the inclusion of these measurements in wake modelling schemes.

Lundquist, J. K.; Bariteau, L.

2015-02-01

342

Site matching of wind turbine generators: A case study  

SciTech Connect

Site matching of wind turbine generators is investigated based on appropriate selection of statistical models and means of wind speed data. The wind speed means are computed using arithmetic mean, root mean square and cubic mean cuberoot. Wind Speed frequency distributions are modeled using Weibull and Rayleigh probability density functions. Wind speed data of an existing wind power station, located at Kappadagudda, Karnataka, India, is used for computational purposes. The analytically obtained capacity factors are validated by comparing with the actual capacity factors obtained at Kappadagudda. It is observed that the capacity factors computed from the Weibull statistical model using cubic mean of wind speed data fairly match the actual capacity factors obtained from Kappadagudda wind power station. Various commercially available wind turbine generators are used for site matching study. The model described in the paper is useful for planning of wind power stations as it can be applied for accurate assessment of wind power potential at a site.

Jangamshetti, S.H.; Rau, V.G.

1999-12-01

343

Large wind turbine generators. [NASA program status and potential costs  

NASA Technical Reports Server (NTRS)

The large wind turbine portion of the Federal Wind Energy Program consists of two major project efforts: (1) the Mod-0 test bed project for supporting research technology, and (2) the large experimental wind turbines for electric utility applications. The Mod-0 has met its primary objective of providing the entire wind energy program with early operations and performance data. The large experimental wind turbines to be tested in utility applications include three of the Mod-0A (200 kW) type, one Mod-1 (2000 kW), and possibly several of the Mod-2 (2500 kW) designs. This paper presents a description of these wind turbine systems, their programmatic status, and a summary of their potential costs.

Thomas, R. L.; Donovon, R. M.

1978-01-01

344

Turbine Inflow Characterization at the National Wind Technology Center  

SciTech Connect

Utility-scale wind turbines operate in dynamic flows that can vary significantly over timescales from less than a second to several years. To better understand the inflow to utility-scale turbines, two inflow towers were installed and commissioned at the National Renewable Energy Laboratory's (NREL) National Wind Technology Center near Boulder, Colorado, in 2011. These towers are 135 m tall and instrumented with a combination of sonic anemometers, cup anemometers, wind vanes, and temperature measurements to characterize the inflow wind speed and direction, turbulence, stability and thermal stratification to two utility-scale turbines. Herein, we present variations in mean and turbulent wind parameters with height, atmospheric stability, and as a function of wind direction that could be important for turbine operation as well as persistence of turbine wakes. Wind speed, turbulence intensity, and dissipation are all factors that affect turbine performance. Our results show that these all vary with height across the rotor disk, demonstrating the importance of measuring atmospheric conditions that influence wind turbine performance at multiple heights in the rotor disk, rather than relying on extrapolation from lower levels.

Clifton, A.; Schreck, S.; Scott, G.; Kelley, N.; Lundquist, J. K.

2012-01-01

345

Turbine Inflow Characterization at the National Wind Technology Center: Preprint  

SciTech Connect

Utility-scale wind turbines operate in dynamic flows that can vary significantly over timescales from less than a second to several years. To better understand the inflow to utility-scale turbines, two inflow towers were installed and commissioned at the National Renewable Energy Laboratory's (NREL) National Wind Technology Center near Boulder, Colorado, in 2011. These towers are 135 m tall and instrumented with a combination of sonic anemometers, cup anemometers, wind vanes, and temperature measurements to characterize the inflow wind speed and direction, turbulence, stability and thermal stratification to two utility-scale turbines. Herein, we present variations in mean and turbulent wind parameters with height, atmospheric stability, and as a function of wind direction that could be important for turbine operation as well as persistence of turbine wakes. Wind speed, turbulence intensity, and dissipation are all factors that affect turbine performance. Our results shown that these all vary with height across the rotor disk, demonstrating the importance of measuring atmospheric conditions that influence wind turbine performance at multiple heights in the rotor disk, rather than relying on extrapolation from lower levels.

Clifton, A.; Schreck, S.; Scott, G.; Kelley, N.; Lundquist, J.

2012-01-01

346

Thermal barrier coatings for turbine components  

DOEpatents

A turbine component, such as a turbine blade having a metal substrate (22) is coated with a metal MCrAlY alloy layer (24) and then a thermal barrier layer (20) selected from LaAlO.sub.3, NdAlO.sub.3, La.sub.2 Hf.sub.2 O.sub.7, Dy.sub.3 Al.sub.5 O.sub.12, HO.sub.3 Al.sub.3 O.sub.12, ErAlO.sub.3, GdAlO.sub.3, Yb.sub.2 Ti.sub.2 O.sub.7, LaYbO.sub.3, Gd.sub.2 Hf.sub.2 O.sub.7 or Y.sub.3 Al.sub.5 O.sub.12.

Subramanian, Ramesh (Oviedo, FL); Sabol, Stephen M. (Orlando, FL); Goedjen, John G. (Oviedo, FL); Sloan, Kelly M. (Bethesda, MD); Vance, Steven J. (Orlando, FL)

2002-01-01

347

Operating wind turbines in strong wind conditions by using feedforward-feedback control  

NASA Astrophysics Data System (ADS)

Due to the increasing penetration of wind energy into power systems, it becomes critical to reduce the impact of wind energy on the stability and reliability of the overall power system. In precedent works, Shen and his co-workers developed a re-designed operation schema to run wind turbines in strong wind conditions based on optimization method and standard PI feedback control, which can prevent the typical shutdowns of wind turbines when reaching the cut-out wind speed. In this paper, a new control strategy combing the standard PI feedback control with feedforward controls using the optimization results is investigated for the operation of variable-speed pitch-regulated wind turbines in strong wind conditions. It is shown that the developed control strategy is capable of smoothening the power output of wind turbine and avoiding its sudden showdown at high wind speeds without worsening the loads on rotor and blades.

Feng, Ju; Sheng, Wen Zhong

2014-12-01

348

AGGREGATED MODELLING OF WIND PARKS WITH VARIABLE SPEED WIND TURBINES IN POWER SYSTEM DYNAMICS SIMULATIONS  

Microsoft Academic Search

More and more wind turbines are made part of electrical power systems, in order to reduce the adverse environmental impact of conventional electrical power generation. A tendency to erect these turbines in wind parks, that are connected to the high voltage transmission grid can be observed. To facilitate the investigation of the impact of a wind park on the dynamics

J. G. Slootweg; S. W. H. de Haan; H. Polinder; W. L. Kling

2002-01-01

349

Composite rotor blades for wind turbine generators  

NASA Astrophysics Data System (ADS)

The materials, techniques, and methods used to construct a 150 ft test blade, two 31 ft blades for a 40 kW WECS, and rotor blades for the Mod-1 wind turbine are described. Considerations of strength, stiffness, and mass distributions, as well as cost, led to the choice of filament wound fiberglass/epoxy material using transverse filament tape which has structural fibers running across the width of the tape. A number of 90 deg windings were added to the rotor after tape winding to provide compaction and hoop strength. Curing comprised five hours at 180 F. The Mod-1 blades were required to match the steel blades in weight, stiffness, deflection, and frequencies. The finished product weighed 20,000 lb and featured a metal tip cap and braided wire trailing edge strap for lightning protection. The 40 kW was a NACA 23018 in the center and 23012 at the tip, while the Mod-1 blade was a NACA 23025 in the center and 23015 at the tip.

Weigel, W. D.

350

Application of dynamic inflow theory to wind turbine rotors  

NASA Astrophysics Data System (ADS)

Dynamic inflow models originally developed for rotorcraft applications were modified for calculation of the aerodynamic loads on wind turbine rotors. The dynamic inflow models used in this study include the simple Pitt and Peters model, the generalized dynamic wake (GDW) model and a newly developed annular section version of Pitt and Peters (P&P) model. The annular section model divides the rotor plane into ring-shaped sections and applies the Pitt and Peters model to each section separately. The dynamic inflow models were compared with the blade element and momentum (BEM) model and field measurement data from the Tjaereborg Turbine in Denmark that were published by The Netherlands Energy Research Foundation. It was shown that the computer models predicted similar results in the calculation of rotor power. The wake skew angle of the GDW model was modified to add directional sensitivity to the model in both the vertical and horizontal directions. This enabled the model to perform correctly with any wake skew angle. The time constant for the changes of induced velocity was reviewed for wind turbine rotor application. The time constant was estimated from the measurement data on the Tjaereborg Turbine. However, the field measurement data could not conclusively support the prediction on the time constant, because only an insufficient number of reliable field measurement data were available. The dynamic inflow models predicted the blade loads far better than the BEM model during yawed operations. Even when the wind condition was steady, the yaw error induced dynamic effects on the blade load and significant dynamic inflow effects. Both the annular section model and the original P&P model predicted the variation of the blade load well. However, only the GDW model predicted the 3P components of the variation in the blade flap bending moment. The dynamic stall effect was found to have limited influence in the tested cases, because of the large size of the test turbine and its associated long time scale of load fluctuation due to the yaw error. The dynamic inflow models experienced instability at very low wind speeds during the transition between the windmill state and propeller state.

Suzuki, Akihiro

2000-10-01

351

Duration Test Report for the SWIFT Wind Turbine  

SciTech Connect

This test was conducted as part of the U.S. Department of Energy's (DOE) Independent Testing project. This project was established to help reduce the barriers of wind energy expansion by providing independent testing results for small turbines. Three turbines where selected for testing at the National Wind Technology Center (NWTC) as a part of round two of the Small Wind Turbine Independent Testing project. Duration testing is one of up to 5 tests that may be performed on the turbines. Other tests include power performance, safety and function, noise, and power quality. The results of the testing will provide the manufacturers with reports that may be used for small wind turbine certification.

Mendoza, I.; Hur, J.

2013-01-01

352

Safety and Function Test Report for the SWIFT Wind Turbine  

SciTech Connect

This test was conducted as part of the U.S. Department of Energy's (DOE) Independent Testing project. This project was established to help reduce the barriers of wind energy expansion by providing independent testing results for small turbines. Three turbines where selected for testing at the National Wind Technology Center (NWTC) as a part of round two of the Small Wind Turbine Independent Testing project. Safety and Function testing is one of up to 5 tests that may be performed on the turbines. Other tests include power performance, duration, noise, and power quality. The results of the testing will provide the manufacturers with reports that may be used for small wind turbine certification.

Mendoza, I.; Hur, J.

2013-01-01

353

A simple method of estimating wind turbine blade fatigue at potential wind turbine sites  

SciTech Connect

This paper presents a technique of estimating blade fatigue damage at potential wind turbine sites. The cornerstone of this technique is a simple model for the blade`s root flap bending moment. The model requires as input a simple set of wind measurements which may be obtained as part of a routine site characterization study. By using the model to simulate a time series of the root flap bending moment, fatigue damage rates may be estimated. The technique is evaluated by comparing these estimates with damage estimates derived from actual bending moment data; the agreement between the two is quite good. The simple connection between wind measurements and fatigue provided by the model now allows one to readily discriminate between damaging and more benign wind environments.

Barnard, J.C.; Wendell, L.L.

1995-06-01

354

Active disturbance rejection based pitch control of variable speed wind turbine  

Microsoft Academic Search

Pitch system is a complicated nonlinear system disturbed by many uncertainties and is a key part of wind turbine system. When wind speed exceeds rated cut-in speed, pitch angle is changed to control wind power conversion efficiency, thus capturing rated power from wind and protecting wind turbine from damage. In this paper, based on the analysis of wind turbine aerodynamic,

Wenjing Zhang; Hongze Xu

2011-01-01

355

Turbine layout effects on the turbulent flow structure in (nearly) fully developed wind farms  

NASA Astrophysics Data System (ADS)

Understanding the complex turbulent processes between the atmospheric boundary layer and wind farms with different layouts is essential for improving the energy production of the different turbines in a wind farm. In this study we investigate the turbulent structure of the flow inside and above a large model wind farm (approximately in fully developed conditions). The large array of turbines consisted of several columns spaced three abreast in an aligned configuration. The length of the wind farm was over one order of magnitude of the boundary layer thickness. Turbine spacing of 6, 8, 10 and 12 rotor diameters were considered for analysis. Full characterization of the turbulent flow was obtained between two rows of turbines far inside the wind farm in a vertical plane parallel to the direction of the flow; two spanwise-vertical planes were also included. A cross-wire anemometer was used to obtain high resolution measurements of streamwise and vertical velocity components at various locations at 10 KHz for a sampling period of 120 s at each location. Particle Image Velocimetry (PIV) was used at selected locations in the wind turbine array to better understand the transport processes. Turbulence statistics, scale-to-scale interaction and TKE budget terms are evaluated to determine the role of the turbine layout on the turbulent dynamics of the flow.

Chamorro, L. P.; Arndt, R.; Sotiropoulos, F.

2011-12-01

356

Development tests for the 2.5 megawatt Mod-2 wind turbine generator  

NASA Technical Reports Server (NTRS)

The 2.5 megawatt MOD-2 wind turbine generator test program is discussed. The development of the 2.5 megawatt MOD-2 wind turbine generator included an extensive program of testing which encompassed verification of analytical procedures, component development, and integrated system verification. The test program was to assure achievement of the thirty year design operational life of the wind turbine system as well as to minimize costly design modifications which would otherwise have been required during on site system testing. Computer codes were modified, fatigue life of structure and dynamic components were verified, mechanical and electrical component and subsystems were functionally checked and modified where necessary to meet system specifications, and measured dynamic responses of coupled systems confirmed analytical predictions.

Andrews, J. S.; Baskin, J. M.

1982-01-01

357

Aeroelastic analysis of the Darrieus wind turbine  

SciTech Connect

The stability of small oscillations of the troposkein-shaped blade used on Darrieus wind turbines is investigated. The blade is assumed to be attached to a perfectly rigid rotor shaft and spinning in still air. Linear equations of motion are derived which include the effects of inplane, out-of-plane, and torsional stiffness, mass and aerodynamic center offsets, and the aerodynamic wake. Results presented include the free-vibration characteristics of the rotating blade, stability of the blade rotating in air, and the effects of mass density, mass center offset, and stiffness parameters on the flutter rotation rates. All results are presented in dimensionless form, hence apply to a family of blades.

Meyer, E.E.

1982-01-01

358

An overview of DOE`s wind turbine development programs  

SciTech Connect

The development of technologically advanced, higher efficiency wind turbines continues to be a high priority activity of the US wind industry. The United States Department of Energy (DOE) is conducting and sponsoring a range of programs aimed at assisting the wind industry with system design, development, and testing. The overall goal is to develop systems that can compete with conventional electric generation for $.05/kWh at 5.8 m/s (13 mph sites) by the mid-1990s and with fossil-fuel-based generators for $.04/kWh at 5.8 m/s sites by the year 2000. These goals will be achieved through several programs. The Value Engineered Turbine Program will promote the rapid development of US capability to manufacture wind turbines with known and well documented records of performance, cost, and reliability, to take advantage of near-term market opportunities. The Advanced Wind Turbine Program will assist US industry to develop and integrate innovative technologies into utility-grade wind turbines for the near-term (mid 1990s) and to develop a new generation of turbines for the year 2000. The collaborative Electric Power Research Institute (EPRI)/DOE Utility Wind Turbine Performance Verification Program will deploy and evaluate commercial-prototype wind turbines in typical utility operating environments, to provide a bridge between development programs currently underway and commercial purchases of utility-grade wind turbines. A number of collaborative efforts also will help develop a range of small systems optimized to work in a diesel hybrid environment to provide electricity for smaller non-grid-connected applications.

Laxson, A; Dodge, D; Flowers, L [National Renewable Energy Lab., Golden, CO (United States); Loose, R; Goldman, P [Dept. of Energy, Washington, DC (United States)

1993-09-01

359

Panel resonant behavior of wind turbine blades.  

SciTech Connect

The principal design drivers in the certification of wind turbine blades are ultimate strength, fatigue resistance, adequate tip-tower clearance, and buckling resistance. Buckling resistance is typically strongly correlated to both ultimate strength and fatigue resistance. A composite shell with spar caps forms the airfoil shape of a blade and reinforcing shear webs are placed inside the blade to stiffen the blade in the flap-wise direction. The spar caps are dimensioned and the shear webs are placed so as to add stiffness to unsupported panel regions and reduce their length. The panels are not the major flap-wise load carrying element of a blade; however, they must be designed carefully to avoid buckling while minimizing blade weight. Typically, buckling resistance is evaluated by consideration of the load-deflection behavior of a blade using finite element analysis (FEA) or full-scale static testing of blades under a simulated extreme loading condition. The focus of this paper is on the use of experimental modal analysis to measure localized resonances of the blade panels. It can be shown that the resonant behavior of these panels can also provide a means to evaluate buckling resistance by means of analytical or experimental modal analysis. Further, panel resonances have use in structural health monitoring by observing changes in modal parameters associated with panel resonances, and use in improving panel laminate model parameters by correlation with test data. In recent modal testing of wind turbine blades, a set of panel modes were measured. This paper will report on the findings of these tests and accompanying numerical and analytical modeling efforts aimed at investigating the potential uses of panel resonances for blade evaluation, health monitoring, and design.

Paquette, Joshua A.; Griffith, Daniel Todd

2010-03-01

360

Wind Energy and Climate: Modeling the Atmospheric Impacts of Wind Energy Turbines  

Microsoft Academic Search

The size and number of wind farms is growing across the globe. Wind energy provides the climatic benefit of producing energy without emitting CO2, however wind energy also produces unintended impacts. Large wind farms directly influence the atmospheric boundary layer by (1.) reducing wind speeds, (2.) generating blade scale turbulence in the wake of the turbines, and (3.) generating shear

A. S. Adams; D. W. Keith

2007-01-01

361

SAR-BASED WIND CLIMATOLOGY FOR WIND TURBINES Merete Bruun Christiansen(1)  

E-print Network

) , Donald Thompson(2) , Lars Boye Hansen(3) (1) Wind Energy Department, Risø National Laboratory, Technical of interest. 1. OFFSHORE WIND ENERGY Wind turbines are being installed at offshore locations in several impact is low, as wind farms are typically placed some 10-20 km from the shoreline. The installed wind

362

Integrated numerical method for the prediction of wind turbine noise and the long range propagation  

Microsoft Academic Search

Characteristics of noise propagation from wind turbine have been studied by using the integrated numerical methods based on Ray theory. There are two numerical approaches in this paper. Those are constructing noise sources of wind turbine and computing the noise level on the ground. First of all, the flow fields around the wind turbine blade are calculated using Wind Turbine

Eunkuk Son; Hyunjung Kim; Hogeon Kim; Wooyoung Choi; Soogab Lee

2010-01-01

363

The Potential Health Impact of Wind Turbines Chief Medical Officer of Health (CMOH) Report  

E-print Network

The Potential Health Impact of Wind Turbines Chief Medical Officer of Health (CMOH) Report May 2010 on the potential health impact of wind turbines in collaboration and consultation with a technical working group is available on the potential health impacts of wind turbines? · What is the relationship between wind turbine

Firestone, Jeremy

364

Market penetration of wind turbine concepts over the years Anca D. Hansen1  

E-print Network

strategies. Wind turbine design objectives have thus changed over the years from being conventional becoming larger, wind turbine design concepts have been progressing from fixed speed, stall commonly applied wind turbine designs in the industry today can be categorized into four main wind turbine

365

PERFORMANCE ENHANCEMENT OF WIND TURBINE POWER REGULATION BY SWITCHED LINEAR CONTROL  

E-print Network

there has been rapid development of wind turbine technology. The standard commercial design of turbinePERFORMANCE ENHANCEMENT OF WIND TURBINE POWER REGULATION BY SWITCHED LINEAR CONTROL D.J.Leith W Power regulation of horizontal-axis grid-connected up-wind constant-speed pitch-regulated wind turbines

Duffy, Ken

366

Voltage grid support of DFIG wind turbines during grid faults Anca D. Hansen1  

E-print Network

) wind turbines address primarily the design of DFIG wind turbine control with special focus on power and the wind turbine grid support capability. Fault ride-through capability addresses primarily the design. This paper addresses the design of the DFIG wind turbine voltage control and protection strategy, which

367

Ris-R-1000(EN) Cost Optimization of Wind Turbines for  

E-print Network

contains a preliminary investigation of site specific design of off- shore wind turbines for a large off using a design tool for wind turbines that involve numerical optimization and aeroelastic calculations carried out to find the optimum overall off-shore wind turbine design. A wind turbine for the off- shore

368

Turbine engine component with cooling passages  

DOEpatents

A component for use in a turbine engine including a first member and a second member associated with the first member. The second member includes a plurality of connecting elements extending therefrom. The connecting elements include securing portions at ends thereof that are received in corresponding cavities formed in the first member to attach the second member to the first member. The connecting elements are constructed to space apart a first surface of the second member from a first surface of the first member such that at least one cooling passage is formed between adjacent connecting elements and the first surface of the second member and the first surface of the first member.

Arrell, Douglas J. (Oviedo, FL); James, Allister W. (Orlando, FL)

2012-01-17

369

Quantifying the hurricane risk to offshore wind turbines  

PubMed Central

The U.S. Department of Energy has estimated that if the United States is to generate 20% of its electricity from wind, over 50 GW will be required from shallow offshore turbines. Hurricanes are a potential risk to these turbines. Turbine tower buckling has been observed in typhoons, but no offshore wind turbines have yet been built in the United States. We present a probabilistic model to estimate the number of turbines that would be destroyed by hurricanes in an offshore wind farm. We apply this model to estimate the risk to offshore wind farms in four representative locations in the Atlantic and Gulf Coastal waters of the United States. In the most vulnerable areas now being actively considered by developers, nearly half the turbines in a farm are likely to be destroyed in a 20-y period. Reasonable mitigation measures—increasing the design reference wind load, ensuring that the nacelle can be turned into rapidly changing winds, and building most wind plants in the areas with lower risk—can greatly enhance the probability that offshore wind can help to meet the United States’ electricity needs. PMID:22331894

Rose, Stephen; Jaramillo, Paulina; Small, Mitchell J.; Grossmann, Iris; Apt, Jay

2012-01-01

370

Quantifying the hurricane risk to offshore wind turbines.  

PubMed

The U.S. Department of Energy has estimated that if the United States is to generate 20% of its electricity from wind, over 50 GW will be required from shallow offshore turbines. Hurricanes are a potential risk to these turbines. Turbine tower buckling has been observed in typhoons, but no offshore wind turbines have yet been built in the United States. We present a probabilistic model to estimate the number of turbines that would be destroyed by hurricanes in an offshore wind farm. We apply this model to estimate the risk to offshore wind farms in four representative locations in the Atlantic and Gulf Coastal waters of the United States. In the most vulnerable areas now being actively considered by developers, nearly half the turbines in a farm are likely to be destroyed in a 20-y period. Reasonable mitigation measures--increasing the design reference wind load, ensuring that the nacelle can be turned into rapidly changing winds, and building most wind plants in the areas with lower risk--can greatly enhance the probability that offshore wind can help to meet the United States' electricity needs. PMID:22331894

Rose, Stephen; Jaramillo, Paulina; Small, Mitchell J; Grossmann, Iris; Apt, Jay

2012-02-28

371

Fatigue case study and reliability analyses for wind turbines  

SciTech Connect

Modern wind turbines are fatigue critical machines used to produce electrical power. To insure long term, reliable operation, their structure must be optimized if they are to be economically viable. The fatigue and reliability projects in Sandia`s Wind Energy Program are developing the analysis tools required to accomplish these design requirements. The first section of the paper formulates the fatigue analysis of a wind turbine using a cumulative damage technique. The second section uses reliability analysis for quantifying the uncertainties and the inherent randomness associated with turbine performance and the prediction of service lifetimes. Both research areas are highlighted with typical results.

Sutherland, H.J.; Veers, P.S.

1994-12-31

372

Assessing Novel Foundation Options for Offshore Wind Turbines  

E-print Network

Assessing Novel Foundation Options for Offshore Wind Turbines B.W. Byrne, BE(Hons), BCom, MA, DPhil G.T. Houlsby, MA, DSc, FREng, FICE Oxford University, UK SYNOPSIS Offshore wind farms, and of these wind power is the only one to be exploited on a commercial scale at present. Three major offshore

Byrne, Byron

373

Evaluation of a wind turbine electric power generator  

NASA Astrophysics Data System (ADS)

A technical assessment of the aerodynamic performance of the wind wheel turbine (WWT) is reported. The potential of the WWT in utilizing wind as an alternate power source was evaluated. Scaling parameters were developed to predict the aerodynamic performance of WWT prototype sized to produce 3, 9, 30, and 100 kw outputs in a 6.7 m/sec wind.

Swim, W. B.

1981-10-01

374

Mars Technologies Spawn Durable Wind Turbines  

NASA Technical Reports Server (NTRS)

Sometimes referred to as regenerative life support systems, the concept includes an enclosed self-sufficient habitat that can independently support life for years on end. Such a system aims not only to produce its own food and water but to purify air and convert waste into useful byproducts. In the early 1990s, NASA was planning for an extended stay on Mars, and Bubenheim and his Ames colleagues were concentrating efforts on creating a complete ecological system to sustain human crewmembers during their time on the Red Planet. The main barrier to developing such a system, he says, is energy. Mars has no power plants, and a regenerative system requires equipment that runs on electricity to do everything from regulating humidity in the atmosphere to monitoring the quality of recycled water. The Ames group started looking at how to best make power on a planet that is millions of miles away from Earth and turned to a hybrid concept combining wind and solar power technologies. The reason was that Mars experiences frequent dust storms that can block nearly all sunlight. When theres a dust storm and the wind is blowing, the wind system could be the dominant power source. When the wind is not blowing and the sun is out, photovoltaics could be the dominant source, says Bubenheim.To develop and test the wind power technology, Ames turned to a remote, harsh environment here on Earth: the South Pole. The South Pole was a really good analog for Mars, says Bubenheim. The technology features for going to Mars were the same technology features needed to make something work at the South Pole.Around the same time that NASA started investigating energy technologies for the Red Planet, the National Science Foundation (NSF) was working on a redesign of their station at the South Pole. To power its operations, NSF used fuel that it flew to the remote location, but the Foundation recognized the benefits of also using onsite renewable energy technologies. In the winter they have small crews and their power requirements are less, says Bubenheim. In the summers, they bring in larger groups and photovoltaics could supply a lot of power. Using renewable energy technology could be a way of reducing the amount of fuel they have to fly in.Technology TransferTo advance wind turbine technology to meet the requirements of extremely harsh environments like that on Mars, Ames partnered with NSF and the Department of Energy. It was clear that a lot of the same features were also desirable for the cold regions of the Earth, says Bubenheim. NASA took the leadership on the team because we had the longest-term technology a Mars turbine. Years before, NSF had worked with a company called Northern Power Systems (NPS), based in Barre, Vermont, to deploy a 3-kilowatt wind turbine on Black Island off the coast of Antarctica.Sometimes referred to as regenerative life support systems, the concept includes an enclosed self-sufficient habitat that can independently support life for years on end. Such a system aims not only to produce its own food and water but to purify air and convert waste into useful byproducts. In the early 1990s, NASA was planning for an extended stay on Mars, and Bubenheim and his Ames colleagues were concentrating efforts on creating a complete ecological system to sustain human crewmembers during their time on the Red Planet. The main barrier to developing such a system, he says, is energy. Mars has no power plants, and a regenerative system requires equipment that runs on electricity to do everything from regulating humidity in the atmosphere to monitoring the quality of recycled water. The Ames group started looking at how to best make power on a planet that is millions of miles away from Earth and turned to a hybrid concept combining wind and solar power technologies. The reason was that Mars experiences frequent dust storms that can block nearly all sunlight. When there's a dust storm and the wind is blowing, the wind system could be the dominant power source. When the wind is not blowing and the sun is out, photovoltaics could be the domina

Bubenheim, David L.

2013-01-01

375

Assessing the representativeness of wind data for wind turbine site evaluation  

NASA Technical Reports Server (NTRS)

Once potential wind turbine sites (either for single installations or clusters) are identified through siting procedures, actual evaluation of the sites must commence. This evaluation is needed to obtain estimates of wind turbine performance and to identify hazards to the machine from the turbulence component of the atmosphere. These estimates allow for more detailed project planning and for preliminary financing arrangements to be secured. The site evaluation process can occur in two stages: (1) utilizing existing nearby data, and (2) establishing and monitoring an onsite measurement program. Since step (2) requires a period of at least 1 yr or more from the time a potential site has been identified, step (1) is often an essential stage in the preliminary evaluation process. Both the methods that have been developed and the unknowns that still exist in assessing the representativeness of available data to a nearby wind turbine site are discussed. How the assessment of the representativeness of available data can be used to develop a more effective onsite meteorological measurement program is also discussed.

Renne, D. S.; Corotis, R. B.

1982-01-01

376

Cost Study for Large Wind Turbine Blades  

SciTech Connect

The cost study for large wind turbine blades reviewed three blades of 30 meters, 50 meters, and 70 meters in length. Blade extreme wind design loads were estimated in accordance with IEC Class I recommendations. Structural analyses of three blade sizes were performed at representative spanwise stations assuming a stressed shell design approach and E-glass/vinylester laminate. A bill of materials was prepared for each of the three blade sizes using the laminate requirements prepared during the structural analysis effort. The labor requirements were prepared for twelve major manufacturing tasks. TPI Composites developed a conceptual design of the manufacturing facility for each of the three blade sizes, which was used for determining the cost of labor and overhead (capital equipment and facilities). Each of the three potential manufacturing facilities was sized to provide a constant annual rated power production (MW per year) of the blades it produced. The cost of the production tooling and overland transportation was also estimated. The results indicate that as blades get larger, materials become a greater proportion of total cost, while the percentage of labor cost is decreased. Transportation costs decreased as a percentage of total cost. The study also suggests that blade cost reduction efforts should focus on reducing material cost and lowering manufacturing labor, because cost reductions in those areas will have the strongest impact on overall blade cost.

ASHWILL, THOMAS D.

2003-05-01

377

Yaw dynamics of horizontal axis wind turbines  

SciTech Connect

Designers of a horizontal axis wind turbine yaw mechanism are faced with a difficult decision. They know that if they elect to use a yaw- controlled rotor then the system will suffer increased initial cost and increased inherent maintenance and reliability problems. On the other hand, if they elect to allow the rotor to freely yaw they known they will have to account for unknown and random, though bounded, yaw rates. They will have a higher-risk design to trade-off against the potential for cost savings and reliability improvement. The risk of a yaw-free system could be minimized if methods were available for analyzing and understanding yaw behavior. The complexity of yaw behavior has, until recently, discouraged engineers from developing a complete yaw analysis method. The objectives of this work are to (1) provide a fundamental understanding of free-yaw mechanics and the design concepts most effective at eliminating yaw problems, and (2) provide tested design tools and guidelines for use by free-yaw wind systems manufacturers. The emphasis is on developing practical and sufficiently accurate design methods.

Hansen, A.C. (Utah Univ., Salt Lake City, UT (United States))

1992-05-01

378

Comparison of three methods for wind turbine capacity factor estimation.  

PubMed

Three approaches to calculating capacity factor of fixed speed wind turbines are reviewed and compared using a case study. The first "quasiexact" approach utilizes discrete wind raw data (in the histogram form) and manufacturer-provided turbine power curve (also in discrete form) to numerically calculate the capacity factor. On the other hand, the second "analytic" approach employs a continuous probability distribution function, fitted to the wind data as well as continuous turbine power curve, resulting from double polynomial fitting of manufacturer-provided power curve data. The latter approach, while being an approximation, can be solved analytically thus providing a valuable insight into aspects, affecting the capacity factor. Moreover, several other merits of wind turbine performance may be derived based on the analytical approach. The third "approximate" approach, valid in case of Rayleigh winds only, employs a nonlinear approximation of the capacity factor versus average wind speed curve, only requiring rated power and rotor diameter of the turbine. It is shown that the results obtained by employing the three approaches are very close, enforcing the validity of the analytically derived approximations, which may be used for wind turbine performance evaluation. PMID:24587755

Ditkovich, Y; Kuperman, A

2014-01-01

379

Impact of wind turbine noise in the Netherlands.  

PubMed

The Dutch government aims at an increase of wind energy up to 6 000 MW in 2020 by placing new wind turbines on land or offshore. At the same time, the existing noise legislation for wind turbines is being reconsidered. For the purpose of establishing a new noise reception limit value expressed in L den , the impact of wind turbine noise under the given policy targets needs to be explored. For this purpose, the consequences of different reception limit values for the new Dutch noise legislation have been studied, both in terms of effects on the population and regarding sustainable energy policy targets. On the basis of a nation-wide noise map containing all wind turbines in The Netherlands, it is calculated that 3% of the inhabitants of The Netherlands are currently exposed to noise from wind turbines above 28 dB(A) at the fa?ade. Newly established dose-response relationships indicate that about 1500 of these inhabitants are likely to be severely annoyed inside their dwellings. The available space for new wind turbines strongly depends on the noise limit value that will be chosen. This study suggests an outdoor A-weighted reception limit of L den = 45 dB as a trade-off between the need for protection against noise annoyance and the feasibility of national targets for renewable energy. PMID:22122963

Verheijen, Edwin; Jabben, Jan; Schreurs, Eric; Smith, Kevin B

2011-01-01

380

Investigation of the effect of bending twisting coupling on the loads in wind turbines with superelement blade definition  

NASA Astrophysics Data System (ADS)

Bending-twisting coupling in the composite blades is exploited for load alleviation in the whole turbine system. For the purpose of the study, inverse design of a reference blade is performed such that sectional beam properties of the 3D blade design approximately match the sectional beam properties of NREL's 5MW turbine blade. In order to appropriately account for the bending-twisting coupling effect, dynamic superelement of the blade is created and introduced into the multi-body dynamic model of the wind turbine system. Initially, a comparative study is conducted on the performance of wind turbines which have blades defined as superelements and geometrically nonlinear beams, and conclusions are inferred with regard to the appropriateness of the use of superelement blade definition in the transient analysis of the 5MW wind turbine system that is set up in the present study. Multi-body dynamic simulations of the wind turbine system are performed for the power production load case with the constant wind and the normal turbulence model as external wind loadings. For the internal loads, fatigue damage equivalent load is used as the metric to assess the effect of bending-twisting coupling on the load alleviation in the whole wind turbine system. Results show that in the overall, through the bending-twisting coupling induced with the use of off-axis plies in the main spar caps of the blade, damage equivalent loads associated with the critical load components can be reduced in the wind turbine system.

Gözcü, M. O.; Kayran, A.

2014-06-01

381

Turbine layout effects on the flow structure inside an above large wind farms  

NASA Astrophysics Data System (ADS)

An understanding of the role of the wind farm layout on the vertical momentum transport above a wind farm is essential to improve energy production of the different turbines. We investigate the turbulent structure of the flow inside and above a large model wind farm (roughly in fully developed conditions). The large array of turbines consisted of several columns of turbines spaced three abreast in an aligned configuration. The length of the wind farm was over fifteen boundary layer thicknesses. Turbine spacing of 6, 8, 10 and 12 rotor diameter was considered for the analysis. Full characterization of the turbulent flow was obtained between two rows of turbines far inside the wind farms in a vertical plane parallel to the direction of the flow and two spanwise-vertical planes were also included. A cross-wire anemometer was used to obtain high resolution measurements of streamwise and vertical velocity components at various locations at 10 KHz for a sampling period of 120 s at each location. Turbulence statistics, scale-to-scale interaction and TKE budget terms are evaluated to determine the role of the turbine layout on the turbulent dynamics of the flow.

Chamorro, Leonardo; Arndt, Roger; Sotiropoulos, Fotis

2011-11-01

382

Design of a wind turbine-generator system considering the conformability to wind velocity fluctuations  

SciTech Connect

The conformability of the rated power output of the wind turbine-generator system and of the wind turbine type to wind velocity fluctuations are investigated with a simulation model. The authors examine three types of wind turbines: the Darrieus-Savonius hybrid, the Darrieus proper and the Propeller. These systems are mainly operated at a constant tip speed ratio, which refers to a maximum power coefficient points. As a computed result of the net extracting power, the Darrieus turbine proper has little conformability to wind velocity fluctuations because of its output characteristics. As for the other turbines, large-scale systems do not always have an advantage over small-scale systems as the effect of its dynamic characteristics. Furthermore, it is confirmed that the net extracting power of the Propeller turbine, under wind direction fluctuation, is much reduced when compared with the hybrid wind turbine. Thus, the authors conclude that the appropriate rated power output of the system exists with relation to the wind turbine type for each wind condition.

Wakui, Tetsuya; Hashizume, Takumi; Outa, Eisuke

1999-07-01

383

Aeroelastic stability analysis of a Darrieus wind turbine  

SciTech Connect

An aeroelastic stability analysis has been developed for predicting flutter instabilities on vertical axis wind turbines. The analytical model and mathematical formulation of the problem are described as well as the physical mechanism that creates flutter in Darrieus turbines. Theoretical results are compared with measured experimental data from flutter tests of the Sandia 2 Meter turbine. Based on this comparison, the analysis appears to be an adequate design evaluation tool.

Popelka, D.

1982-02-01

384

Aeroelastic stability analysis of a Darrieus wind turbine  

NASA Astrophysics Data System (ADS)

An aeroelastic stability analysis was developed for predicting flutter instabilities on vertical axis wind turbines. The analytical model and mathematical formulation of the problem are described as well as the physical mechanism that creates flutter in Darrieus turbines. Theoretical results are compared with measured experimental data from flutter tests of the Sandia 2 Meter turbine. Based on this comparison, the analysis appears to be an adequate design evaluation tool.

Popelka, D.

1982-02-01

385

Design of wind turbines with Ultra-High Performance Concrete  

E-print Network

Ultra-High Performance Concrete (UHPC) has proven an asset for bridge design as it significantly reduces costs. However, UHPC has not been applied yet to wind turbine technology. Design codes do not propose any recommendations ...

Jammes, François-Xavier

2009-01-01

386

Mod-2 wind turbine system development. Volume 1: Executive summary  

NASA Technical Reports Server (NTRS)

The development of the MOD-2 wind turbine through acceptance testing and initial operational evaluation is documented. Pitch control hydraulic system, yaw control system, drive train, electrical power station, control system, operations and maintenance experience, and availability are discussed.

1982-01-01

387

Fuzzy-polar control of wind-turbine generator  

SciTech Connect

This paper presents a wind-turbine blade pitch angle controller based on fuzzy polar technique. the technique takes advantage of fuzzy-linguistic modeling in expressing the natural non-linearity or imprecision of the wind-turbine system in determining pitch angles for speed and power regulation. The fuzzy-polar method presents wind-turbine state in the phase-plane in terms of its rotational speed deviation and acceleration. The state vectors thus derived serve as an indicator of the magnitude of departure from the nominal operating point. In order to shift operating state back to the phase plane origin, an acceleration or deceleration control is applied through the pitch-angle adjustment mechanism as defined by the fuzzy-linguistic control law. The performance of the pitch control design method is demonstrated on a simulated wind-turbine-driven synchronous generator.

Idowu, P. [Penn State Univ., Middletown, PA (United States)

1995-12-31

388

The influence of thunderstorm downbursts on wind turbine design.  

E-print Network

??The International Electrotechnical Commission (IEC) standard 61400-1 for the design of wind turbines does not explicitly address site-specific conditions associated with anomalous atmospheric events or… (more)

Nguyen, Hieu Huy, 1980-

2012-01-01

389

Coupled Dynamic Analysis of Multiple Unit Floating Offshore Wind Turbine  

E-print Network

In the present study, a numerical simulation tool has been developed for the rotor-floater-tether coupled dynamic analysis of Multiple Unit Floating Offshore Wind Turbine (MUFOWT) in the time domain including aero-blade-tower dynamics and control...

Bae, Yoon Hyeok

2013-04-23

390

Performance Study and Optimization of the Zephergy Wind Turbine  

E-print Network

There are many problems associated with small wind turbines, such as small Reynolds number and poor starting performance, that make them much more expensive than the large ones per unit power. New technologies are needed to improve the quality...

Soodavi, Moein

2013-12-04

391

Basic Integrative Models for Offshore Wind Turbine Systems  

E-print Network

This research study developed basic dynamic models that can be used to accurately predict the response behavior of a near-shore wind turbine structure with monopile, suction caisson, or gravity-based foundation systems. The marine soil conditions...

Aljeeran, Fares

2012-07-16

392

Variable speed generator technology options for wind turbine generators  

NASA Technical Reports Server (NTRS)

The electrical system options for variable speed operation of a wind turbine generator are treated in this paper. The key operating characteristics of each system are discussed and the major advantages and disadvantages of each are identified

Lipo, T. A.

1995-01-01

393

The General Electric MOD-1 wind turbine generator program  

NASA Technical Reports Server (NTRS)

The design, fabrication, installation and checkout of MOD-1, a megawatt class wind turbine generator which generates utility grade electrical power, is described. A MOD-1/MOD-1A tradeoff study is discussed.

Poor, R. H.; Hobbs, R. B.

1979-01-01

394

Superconducting generators for large off shore wind turbines   

E-print Network

This thesis describes four novel superconducting machine concepts, in the pursuit of finding a suitable design for large offshore wind turbines. The designs should be reliable, modular and light-weight. The main novelty ...

Keysan, Ozan

2014-06-30

395

Optimal tuning for a classical wind turbine controller  

NASA Astrophysics Data System (ADS)

Fine tuning of controllers for pitch-torque regulated wind turbines is an opportunity to improve the wind turbine performances and reduce the cost of energy without applying any changes to the design. For this purpose, a method for automatically tune a classical controller based on numerical optimization is developed and tested. To have a better understanding of the problem a parametric analysis of the wind turbine performances due to changes in the controller parameters is first performed. Thereafter results obtained with the automatic tuning show that is possible to identify a finer controller tuning that improves the wind turbine performances. For the case study selected in this work, a 2% cost function reduction is achieved with seven iterations.

Tibaldi, C.; Hansen, M. H.; Henriksen, L. C.

2014-12-01

396

"Design of Offshore Wind Turbines for Hurricane Resilience" Graduate Seminar  

E-print Network

"Design of Offshore Wind Turbines for Hurricane Resilience" Graduate Seminar Thursday, December 5 of designing a Convention Center Hotel in an Urban Setting " Undergraduate Seminar Tuesday October 08, 2013, 12

Connor, Ed

397

Wind Turbine Lightning Protection Project: 1999-2001  

SciTech Connect

A lightning protection research and support program was instituted by NREL to help minimize lightning damage to wind turbines in the United States. This paper provides the results of a field test program, an evaluation of protection on selected turbines, and a literature search as well as the dissemination of the accumulated information.

McNiff, B.

2002-05-01

398

Low cost Darrieus vertical-axis wind turbine design  

Microsoft Academic Search

The main objective of a low cost Darrieus type wind turbine design effort carried out for the U.S. Department of Energy is to obtain realistic fabrication cost data based on current technology. An existing 17 m Sandia research turbine served as a background machine for development of the Low Cost design. Different design aspects of the 17 m Low Cost

D. K. Ai

1979-01-01

399

Thermal stress minimized, two component, turbine shroud seal  

NASA Technical Reports Server (NTRS)

In a turbine machine, a two-component shroud seal which maximizes insulation and sealing around the rotating turbine blades, and is made by independently fabricating each of the two components then joining them together, is disclosed. The two components may be joined together at room temperature. The resulting shroud seal provides greater engine efficiency and thrust.

Handschuh, Robert F. (inventor)

1988-01-01

400

Comparison of Wake Model Simulations with Offshore Wind Turbine Wake Profiles Measured by Sodar  

E-print Network

to be gained from accurate modeling of wind turbine wakes in wind farm design to minimize both power lossesComparison of Wake Model Simulations with Offshore Wind Turbine Wake Profiles Measured by Sodar R of most of the commonly used models for predicting wind speed decrease (wake) downstream of a wind turbine

Pryor, Sara C.

401

58:164 Fundamentals of Wind Turbines (ME:4164:0001)  

E-print Network

will be emphasized: wind energy conversion to useful work; wind turbine aerodynamics; performance; design of wind.10 Aerodynamic Performance Assessment 6 - Conceptual Design of Horizontal Axis Wind Turbines 6.1 Introduction 658:164 ­ Fundamentals of Wind Turbines (ME:4164:0001) Syllabus P. Barry Butler 111 Jessup Hall

Kusiak, Andrew

402

FAROW: A tool for fatigue and reliability of wind turbines  

NASA Astrophysics Data System (ADS)

FAROW is a computer program that evaluates the fatigue and reliability of wind turbine components using structural reliability methods. A deterministic fatigue life formulation is based on functional forms of three basic parts of wind turbine fatigue calculation: (1) the loading environment, (2) the gross level of structural response given the load environment, and (3) the local failure criterion given both load environment and gross stress response. The calculated lifetime is compared with a user specific target lifetime to assess probabilities of premature failure. The parameters of the functional forms can be defined as either constants or random variables. The reliability analysis uses the deterministic lifetime calculation as the limit state function of a FORM/SORM (first and second order reliability methods) calculation based on techniques developed by Rackwitz. Besides probability of premature failure, FAROW calculates the mean lifetime, the relative importance of each of the random variables, and the sensitivity of the results to all of the input parameters, both constant inputs and the parameters that define the random variable inputs. The ability to check the probability of failure with Monte Carlo simulation is included as an option.

Veers, P. S.; Lange, C. H.; Winterstein, S. R.

403

FAROW: A tool for fatigue and reliability of wind turbines  

SciTech Connect

FAROW is a computer program that evaluates the fatigue and reliability of wind turbine components using structural reliability methods. A deterministic fatigue life formulation is based on functional forms of three basic parts of wind turbine fatigue calculation: (1) the loading environment, (2) the gross level of structural response given the load environment, and (3) the local failure criterion given both load environment and gross stress response. The calculated lifetime is compared with a user specific target lifetime to assess probabilities of premature failure. The parameters of the functional forms can be defined as either constants or random variables. The reliability analysis uses the deterministic lifetime calculation as the limit state function of a FORM/SORM (first and second order reliability methods) calculation based on techniques developed by Rackwitz. Besides probability of premature failure, FAROW calculates the mean lifetime, the relative importance of each of the random variables, and the sensitivity of the results to all of the input parameters, both constant inputs and the parameters that define the random variable inputs. The ability to check the probability of failure with Monte Carlo simulation is included as an option.

Veers, P.S. [Sandia National Labs., Albuquerque, NM (US); Lange, C.H.; Winterstein, S.R. [Stanford Univ., CA (US). Civil Engineering Dept.

1993-07-01

404

Analysis of internal drive train dynamics in a wind turbine  

NASA Astrophysics Data System (ADS)

Three types of multibody models are presented for the investigation of the internal dynamics of a drive train in a wind turbine. The first approach is limited to the analysis of torsional vibrations only. Then a rigid multibody model is presented with special focus on the representation of the bearings and gears in the drive train. The generic model implementation can be used for parallel as well as planetary gear stages with both helical and spur gears. Examples for different gear stages describe the use of the presented formulations. Furthermore, the influence of the helix angle and the flexibility of the bearings on the results of eigenmode calculations are discussed. The eigenmodes of a planetary stage are classified as rotational, translational or out-of-plane modes. Thirdly, the extension to a flexible multibody model is presented as a method to include directly the drive train components' flexibilities. Finally, a comparison of two different modelling techniques is discussed for a wind turbine's drive train with a helical parallel gear stage and two planetary gear stages. In addition, the response calculation for a torque input at the generator demonstrates which eigenmodes can be excited through this path. Copyright

Peeters, Joris L. M.; Vandepitte, Dirk; Sas, Paul

2006-01-01

405

Development of the WTS-4 wind turbine design  

NASA Astrophysics Data System (ADS)

Design features, developmental aspects, and financial projections for the WTS-4 4 MW wind turbine are presented. The WTS-4 is a horizontal axis, downwind, two-bladed, variable pitch machine. Start-up is at 7 m/s, rated power is reached at 15 m/s, and shut-down is set at 27 m/s, with all controls operating in a stand-alone mode by means of microprocessors. Each blade is 125 ft long, constructed of filament wound fiberglass reinforced epoxy, and attached at the root to a teetered steel alloy hub, which compensates for the shear caused by the tower shadow. Pitch is controlled by an electrohydraulic mechanism, and can be effected at a rate of 5 deg/s. Details of the nacelle components and costruction are provided, together with features of the system controller and design trade-offs. Cost comparisons with utility scale coal and oil baseload generation plants indicate that wind turbines will become cost competitive by 1985 and are favored thereafter.

Hasbrouck, T. M.; Divalentin, E.

406

Wind turbine acoustics research bibliography with selected annotation  

NASA Technical Reports Server (NTRS)

Citations of documents are included, which represent the state-of-the-art of technology in each of the following acoustics subject areas: Prediction of Wind Turbine Noise; Acoustic Measurements for Wind Tunnels; Effect of Wind Turbine Noise on Building Structures, People and Communities; Atmospheric Propagation; and Measurement Technology Including Wind Screens. Documents are listed in chronological order in each section of the paper, with key documents and associated annotation listed first. The sources are given along with acquisition numbers, when available, to expedite the acquisition of copies of the documents.

Hubbard, Harvey H.; Shepherd, Kevin P.

1988-01-01

407

Analysis of the electrical characteristics of a Westinghouse variable speed generating system for wind turbine applications  

NASA Astrophysics Data System (ADS)

Variable speed electric generating technology can enhance the general use of wind energy in electric utility applications. This enhancement results from two characteristic properties of variable speed wind turbine generators: an improvement in drive train damping characteristics, which results in reduced structural loading on the entire wind turbine system, and an improvement in the overall efficiency by using a more sophisticated electrical generator. Electronic converter systems are the focus of this investigation, particularly the properties of a Westinghouse variable-speed, constant-frequency system with wound-rotor induction generator and a cycloconverter. Experience with solid-state converter systems in large wind turbines is extremely limited. This report presents measurements of electrical performances of the Westinghouse system and is limited to the terminal characteristics of the system. Variable speed generating systems working effectively in utility applications will require a satisfactory interface between the turbine-generator pair and the utility network. The electrical testing described herein focuses largely on the interface characteristics of the generating system. A MOD-0 wind turbine was connected to a very strong system; thus, the voltage distortion was low and the total harmonic distortion in the utility voltage was less than 3 percent (within the 5 percent limit required by most utilities). The largest voltage component of a frequency below 60 Hz was 40 dB down from the 60-Hz component.

Herrera, J. I.; Reddoch, T. W.

1988-02-01

408

Stochastic analysis of wind stream and turbine power  

NASA Astrophysics Data System (ADS)

Stochastic analysis of a high-frequency wind data tape has been performed. The tape includes wind speed and direction as well as wind-turbine-generated power. In an attempt to correlate wind speed with turbine power, data were sampled every 2 s from a United States Department of Energy demonstration 200 kW wind turbine installation. Wind speeds were recorded from three heights on a meteorological tower and from the wind-driven generator. Auto-correlation and spectral density functions were found for both the wind speed and the turbine power. Spatial and temporal averaging was performed, and time-lagged spatial cross-correlations, cross-spectral density functions and coherence functions were computed. A time-lagging technique was used to translate meteorological tower data to the turbine. Nonstationarity in the mean and standard deviation were investigated. These analyses form the bases for data collection procedures for initial site evaluation and for full-scale machine power predictions.

Lou, J.-J.; Corotis, R. B.

1985-01-01

409

Structural Analysis and Design of the Composite Wind Turbine Blade  

Microsoft Academic Search

The wind turbine blade sustains various kinds of loadings during the operation and parking state. Due to the increasing size\\u000a of the wind turbine blade, it is important to arrange the composite materials in a sufficient way to reach the optimal utilization\\u000a of the material strength. Most of the composite blades are made of glass fibers composites while carbon fibers

Wen-Hsiang Wu; Wen-Bin Young

2011-01-01

410

Evaluation of the vertical axis wind turbine at DREO  

Microsoft Academic Search

A Vertical Axis Wind Turbine-Battery Storage System was installed at the Defence Research Establishment Ottawa (DREO) in December 1975 and was operated for three years. The system was instrumented to control and monitor its operation and performance. This report deals with an evaluation study of a Vertical Axis Wind Turbine-Battery Storage System for a low-power unattended power source. The System's

H. R. Braun; D. J. Bristow; S. J. Wake

1980-01-01

411

Post stall airfoil data for wind turbines: wind tunnel test results  

SciTech Connect

Wind turbine blades operate over a wide angle of attack range. Unlike aircraft, a wind turbine's angle of attack range extends deep into stall where the three dimensional performance characteristics of airfoils are not generally known. Peak power predictions upon which wind turbine components are sized depend on a good understanding of a blade's post stall characteristics. The purpose of this wind tunnel study is to characterize the performance characteristics of a blade in stall as a function of its aspect ratio, airfoil thickness and Reynolds number. This report documents results of the wind tunnel investigation of constant chord blades having four aspect ratios, with NACA 44XX series airfoil sections, at angles of attack ranging from -10 to 110/sup 0/. Tests were conducted at Reynolds number ranging from one-quarter million to one million. The thickness ratios studied were 0.18, 0.15, 0.12 and 0.09. The aspect ratios were 6, 9, 12 and infinity. Results of force and pitching moment measurements, over the angle of attack range, for all combinations of Reynolds numbers, thickness and aspect ratios, and the effects of boundary layer tripping, have been presented. Both initial and secondary stall are presented. The maximum drag coefficient is found to occur at an angle of attack of 90/sup 0/. The pitching moment is unstable beyond stall. The lift and post-stall drag coefficients decrease with decreasing aspect ratio. The lift coefficient decreases with decreasing thickness ratio, while the drag coefficient increases. The boundary layer tripping is observed to decrease the lift curve slope and stalling angle of attack. The drag coefficient (with tripping) is significantly affected only at low aspect ratio.

Ostowari, C.; Naik, D.

1984-07-01

412

Operational behavior of a double-fed permanent magnet generator for wind turbines  

E-print Network

Greater efficiency in wind turbine systems is achieved by allowing the rotor to change its rate of rotation as the wind speed changes. The wind turbine system is decoupled from the utility grid and a variable speed operation ...

Reddy, Sivananda Kumjula

2005-01-01

413

Control strategy of a variable speed wind turbine with multipole permanent magnet synchronous generator  

E-print Network

Control strategy of a variable speed wind turbine with multipole permanent magnet synchronous magnet syn- chronous generator (PMSG) and full scale IGBT power converter. A comprehensive dynamical values. Keywords: permanent magnet synchronous generator, variable speed wind turbine, direct driven wind

414

DOE/SNL-TTU scaled wind farm technology facility : research opportunities for study of turbine-turbine interaction.  

SciTech Connect

The proposed DOE/Sandia Scaled Wind Farm Technology Facility (SWiFT) hosted by Texas Tech University at Reese Technology Center in Lubbock, TX, will provide a facility for experimental study of turbine-turbine interaction and complex wind farm aerodynamics. This document surveys the current status of wind turbine wake and turbine-turbine interaction research, identifying knowledge and data gaps that the proposed test site can potentially fill. A number of turbine layouts is proposed, allowing for up to ten turbines at the site.

Barone, Matthew Franklin; White, Jonathan

2011-09-01

415

The role of turbulent mixing in wind turbine wake recovery and wind array performance  

NASA Astrophysics Data System (ADS)

The effect of wind turbine wakes in large offshore wind energy arrays can be a substantial factor in affecting the performance of turbines inside the array. Turbulent mixing plays a key role in the wake recovery, having a significant effect on the length over which the wake is strong enough to affect the performance other turbines significantly. We aim to highlight how turbulence affects wind turbine wakes, first by examining a high resolution CFD model of a single turbine wake validated by LIDAR measurements [1], and secondly with a much larger CFD simulation of Lillgrund offshore wind farm, validated with SCADA data [2]. By comparing the decay rates behind single turbines in environments of different surrounding surface features, ranging from ideal free-slip wind tunnels to mixed-vegetation hills, we suggest that the decay rate of turbine wakes are enhanced by free-stream turbulence, created by topography and ground features. In the context of Lillgrund wind farm, observations and computational results suggest that the wakes created by the turbines in the leading row facing the wind decay much slower than those in second row, or further into the turbine array. This observation can be explained by the diffusive action of upwind turbulence breaking up the wake generated by a turbine rotor. Angus CW Creech, Wolf-Gerrit Früh, Peter Clive (2012). Actuator volumes and hradaptive methods for threedimensional simulation of wind turbine wakes and performance. Wind Energy Vol.15, 847 - 863. Angus C.W. Creech, Wolf-Gerrit Früh, A. Eoghan Maguire (2013). High-resolution CFD modelling of Lillgrund Wind farm. Renewable Energies and Power Quality Journal, Vol. 11

Fruh, Wolf-Gerrit; Creech, Angus; Maguire, Eoghan

2014-05-01

416

Preliminary results of the large experimental wind turbine phase of the national wind energy program  

NASA Technical Reports Server (NTRS)

A major phase of the wind energy program is the development of reliable wind turbines for supplying cost-competitive electrical energy. This paper discusses the preliminary results of two projects in this phase of the program. First an experimental 100 kW wind turbine design and its status are reviewed. Also discussed are the results of two parallel design studies for determining the configurations and power levels for wind turbines with minimum energy costs. These studies show wind energy costs of 7 to 1.5 c/kWH for wind turbines produced in quantities of 100 to 1000 a year and located at sites having average winds of 12 to 18 mph.

Thomas, R. L.; Sholes, J. E.

1975-01-01

417

Gain-scheduled Linear Quadratic Control of Wind Turbines Operating at High Wind Speed  

Microsoft Academic Search

This paper addresses state estimation and linear quadratic (LQ) control of variable speed variable pitch wind turbines. On the basis of a nonlinear model of a wind turbine, a set of operating conditions is identified and a LQ controller is designed for each operating point. The controller gains are then interpolated linearly to get a control law for the entire

K. Z. Ostergaard; Per Brath; Jakob Stoustrup

2007-01-01

418

A wind tunnel investigation of wind turbine wakes: Boundary-layer turbulence and surface roughness effects  

Microsoft Academic Search

Wind turbine wakes are known to have an important effect on power generation and fatigue loads in wind energy parks. Wake characteristics are expected to depend on the incoming atmospheric boundary layer flow statistics (mean velocity and turbulence levels). Here, results are presented from a wind tunnel experiment carried out at the St. Anthony Falls Laboratory atmospheric boundary layer wind

L. Chamorro; F. Porte-Agel

2008-01-01

419

Applications of the Equivalent Wind Method for the Aggregation of DFIG Wind Turbines  

Microsoft Academic Search

Recently wind energy has developed at a fast pace, and it is necessary to develop equivalent models to represent dynamic behaviors of wind farms on power system. This paper investigates the applications of the equivalent wind method for the aggregation of DFIG wind turbines. Simulations in a practical power system have been used to verify the effectiveness of the aggregation.

Z. J. Meng; F. Xue

2011-01-01

420

Reference wind speed distributions and height profiles for wind turbine design and performance evaluation applications. [USA  

Microsoft Academic Search

The purpose of this report is to provide a set of reference or standard values of wind profiles, wind speed distributions and their effects on wind turbine performance for engineering design applications. Based on measured Weibull distribution parameters, representative average, low, and high variance data are given for height profiles of mean, 25 percentile, and 75 percentile wind speeds; and

C. G. Justus; W. R. Hargraves; A. Mikhail

1976-01-01

421

On wind turbine power performance measurements at inclined airflow  

NASA Astrophysics Data System (ADS)

The average airflow inclination in complex terrain may be substantial. The airflow inclination affects wind turbine performance and also affects the cup anemometer being used in power performance measurements. In this article the overall dependence of the power curve on inclined airflow is analysed for its influence on both the wind turbine and the cup anemometer. The wind turbine performance analysis is based on results of measurements and theoretical calculations with the aeroelastic code HAWC coupled to a 3D actuator disc model for varying yaw angle. The cup anemometer analysis at inclined flow is based on an averaging of measured angular characteristics in a wind tunnel with the distribution of airflow inclination angles over time. The relative difference in annual energy production in terrain with inclined airflow compared with flat terrain is simulated for cup anemometers with theoretical optimal angular characteristics for two different definitions of wind speed, as well as for five commercial cup anemometers with measured angular characteristics. Copyright

Pedersen, T. F.

2004-07-01

422

An integrated dynamic model of a flexible wind turbine  

NASA Astrophysics Data System (ADS)

A model to study the dynamic behavior of flexible wind turbines was developed. The different subsystems of the wind turbine are individually modeled with about the same degree of accuracy. The aerodynamic part describes wind shear, gravity effects, unsteady effects, and dynamic inflow. The rotor blades are provided with degrees of freedom in lag and flap directions. The tower construction is modeled including the first bending mode. The first torsional mode of the transmission is included in the model. The model of synchronous generator with dc link consists of a nonlinear fourth order model, including saturation effects. The different models of the subsystems are coupled into one integrated dynamic model which is implemented as simulation code in the DUWECS (Delf University Wind Energy Converter Simulation Package) program. The DUWECS program is developed in such a manner that it is an easy to handle tool for the study of the dynamic features of wind turbine systems.

Bongers, Peter M. M.; Bierbooms, Wim A. A.; Dijkstra, Sjoerd; Vanholten, Theo

1990-06-01

423

Fatigue analysis and testing of wind turbine blades  

NASA Astrophysics Data System (ADS)

This thesis focuses on fatigue analysis and testing of large, multi MW wind turbine blades. The blades are one of the most expensive components of a wind turbine, and their mass has cost implications for the hub, nacelle, tower and foundations of the turbine so it is important that they are not unnecessarily strong. Fatigue is often an important design driver, but fatigue of composites is poorly understood and so large safety factors are often applied to the loads. This has implications for the weight of the blade. Full scale fatigue testing of blades is required by the design standards, and provides manufacturers with confidence that the blade will be able to survive its service life. This testing is usually performed by resonating the blade in the flapwise and edgewise directions separately, but in service these two loads occur at the same time.. A fatigue testing method developed at Narec (the National Renewable Energy Centre) in the UK in which the flapwise and edgewise directions are excited simultaneously has been evaluated by comparing the Palmgren-Miner damage sum around the blade cross section after testing with the damage distribution caused by the service life. A method to obtain the resonant test configuration that will result in the optimum mode shapes for the flapwise and edgewise directions was then developed, and simulation software was designed to allow the blade test to be simulated so that realistic comparisons between the damage distributions after different test types could be obtained. During the course of this work the shortcomings with conventional fatigue analysis methods became apparent, and a novel method of fatigue analysis based on multi-continuum theory and the kinetic theory of fracture was developed. This method was benchmarked using physical test data from the OPTIDAT database and was applied to the analysis of a complete blade. A full scale fatigue test method based on this new analysis approach is also discussed..

Greaves, Peter Robert

424

Testing basic performance of a very small wind turbine designed for multi-purposes  

Microsoft Academic Search

A very small wind turbine system for multi-purposes was developed and its performance was reported in this paper. The rotor diameter of the turbine is 500mm. The tests of the energy output, turbine speed, power coefficient, and torque of turbine were carried out for a wide rage of free stream velocity. The flow around the wind turbine and the influence

Hiroyuki Hirahara; M. Zakir Hossain; Masaaki Kawahashi; Yoshitami Nonomura

2005-01-01

425

Strategies for Refining IEC 61400-2: Wind Turbine Generator Systems - Part 2: Safety of Small Wind Turbines: Preprint  

Microsoft Academic Search

This paper provides a status of the changes currently being made by IEC Maintenance Team 02 (MT02) to the existing IEC 61400-2 ''Safety of small wind turbines.'' In relation to the work done by IEC MT02, work has been done by NREL and Windward Engineering under the DOE\\/NREL Small Wind Turbine (SWT) Project. Aeroelastic models were built and measurements taken

J. J. D. van Dam; T. L. Forsyth; A. C. Hansen

2001-01-01

426

Is a wind turbine a point source? (L).  

PubMed

Measurements show that practically all noise of wind turbine noise is produced by turbine blades, sometimes a few tens of meters long, despite that the model of a point source located at the hub height is commonly used. The plane of rotating blades is the critical location of the receiver because the distances to the blades are the shortest. It is shown that such location requires certain condition to be met. The model is valid far away from the wind turbine as well. PMID:21361413

Makarewicz, Rufin

2011-02-01

427

Proposed Wind Turbine Aeroelasticity Studies Using Helicopter Systems Analysis  

NASA Technical Reports Server (NTRS)

Advanced systems for the analysis of rotary wing aeroelastic structures (helicopters) are being developed at NASA Ames by the Rotorcraft Aeromechanics Branch, ARA. The research has recently been extended to the study of wind turbines, used for electric power generation Wind turbines play an important role in Europe, Japan & many other countries because they are non polluting & use a renewable source of energy. European countries such as Holland, Norway & France have been the world leaders in the design & manufacture of wind turbines due to their historical experience of several centuries, in building complex wind mill structures, which were used in water pumping, grain grinding & for lumbering. Fossil fuel cost in Japan & in Europe is two to three times higher than in the USA due to very high import taxes. High fuel cost combined with substantial governmental subsidies, allow wind generated power to be competitive with the more traditional sources of power generation. In the USA, the use of wind energy has been limited mainly because power production from wind is twice as expensive as from other traditional sources. Studies conducted at the National Renewable Energy Laboratories (NREL) indicate that the main cost in the production of wind turbines is due to the materials & the labor intensive processes used in the construction of turbine structures. Thus, for the US to assume world leadership in wind power generation, new lightweight & consequently very flexible wind turbines, that could be economically mass produced, would have to be developed [4,5]. This effort, if successful, would result in great benefit to the US & the developing nations that suffer from overpopulation & a very high cost of energy.

Ladkany, Samaan G.

1998-01-01

428

Effects of incoming surface wind conditions on the wake characteristics and dynamic wind loads acting on a wind turbine model  

NASA Astrophysics Data System (ADS)

An experimental investigation was conducted to examine the effects of incoming surface wind conditions on the wake characteristics and dynamic wind loads acting on a wind turbine model. The experimental study was performed in a large-scale wind tunnel with a scaled three-blade Horizontal Axial Wind Turbine model placed in two different types of Atmospheric Boundary Layer (ABL) winds with distinct mean and turbulence characteristics. In addition to measuring dynamic wind loads acting on the model turbine by using a force-moment sensor, a high-resolution Particle Image Velocimetry system was used to achieve detailed flow field measurements to characterize the turbulent wake flows behind the model turbine. The measurement results reveal clearly that the discrepancies in the incoming surface winds would affect the wake characteristics and dynamic wind loads acting on the model turbine dramatically. The dynamic wind loads acting on the model turbine were found to fluctuate much more significantly, thereby, much larger fatigue loads, for the case with the wind turbine model sited in the incoming ABL wind with higher turbulence intensity levels. The turbulent kinetic energy and Reynolds stress levels in the wake behind the model turbine were also found to be significantly higher for the high turbulence inflow case, in comparison to those of the low turbulence inflow case. The flow characteristics in the turbine wake were found to be dominated by the formation, shedding, and breakdown of various unsteady wake vortices. In comparison with the case with relatively low turbulence intensities in the incoming ABL wind, much more turbulent and randomly shedding, faster dissipation, and earlier breakdown of the wake vortices were observed for the high turbulence inflow case, which would promote the vertical transport of kinetic energy by entraining more high-speed airflow from above to re-charge the wake flow and result in a much faster recovery of the velocity deficits in the turbine wake.

Tian, Wei; Ozbay, Ahmet; Hu, Hui

2014-12-01

429

The History and State of the Art of Variable-Speed Wind Turbine Technology  

Microsoft Academic Search

Early wind turbines used for performing mechanical work (pumping, grinding and cutting) optimized aerodynamics by being allowed to run at variable speed. Some of the earliest DC electric wind turbines were allowed to run at variable speed. With the advent of grid-connected AC turbines, rotational speeds were limited in order to control the wind turbine AC frequency output to equal

P. W. Carlin; A. S. Laxson; E. B. Muljadi

2003-01-01

430

ENERGY FOR SUSTAINABILITY: HIGHLY COMPLIANT FLOATING OFFSHORE WIND TURBINES: FEASIBILITY ASSESSMENT THROUGH THEORY, SIMULATION AND DESIGN  

E-print Network

ASSESSMENT THROUGH THEORY, SIMULATION AND DESIGN Hundreds of wind turbines have been installed in the oceans turbine. Development of a new simulation method is necessary because conventional wind turbine design, and the result could be a dramatic shift in the design philosophy for floating wind turbines. In addition t

Sweetman, Bert

431

Ris-R-1392(EN) Full scale testing of wind turbine blade  

E-print Network

of some of the work that was carried out in a project called "Improved design for large wind turbine-R-1390(EN) "Fundamentals for improved design of large wind turbine blade of fibre com- posites basedRisø-R-1392(EN) Full scale testing of wind turbine blade to failure - flapwise loading Erik R

432

Advanced Wind Turbine Program Next Generation Turbine Development Project: June 17, 1997--April 30, 2005  

SciTech Connect

This document reports the technical results of the Next Generation Turbine Development Project conducted by GE Wind Energy LLC. This project is jointly funded by GE and the U.S. Department of Energy's National Renewable Energy Laboratory.The goal of this project is for DOE to assist the U.S. wind industry in exploring new concepts and applications of cutting-edge technology in pursuit of the specific objective of developing a wind turbine that can generate electricity at a levelized cost of energy of $0.025/kWh at sites with an average wind speed of 15 mph (at 10 m height).

GE Wind Energy, LLC

2006-05-01

433

Study of composite wind turbine spars  

NASA Astrophysics Data System (ADS)

This report presents a theoretical, numerical and experimental study of composite wind turbine spars under bending loads. Spars were made from commercially available glass/ carbon fiber material. The spars were composed of uniaxial (0°) flanges and biaxial (+/-45°) shear webs. Items of particular study were co-block polymer additives in vinyl ester resins, a presumably new spar design, and using carbon fiber pultrusions for spar caps (flanges). Composites are very strong and thus tend to be thin, which exacerbates the problem of buckling. Further, fibers also buckle at the micro level, leading to lower effective compression strength than tensile strength of a composite. Many structures tend to buckle in out of plane direction which can cause early and abrupt failure. A 3-point bend test rig was manufactured in-house for experimentally testing composite spars. The experiments indicated abrupt failure without any sign or other form of damage. Limited number of spars was made with slightly different construction. All spars were subjected to same testing environment. Finite element analyses were performed in order to shed light on the failure mechanisms leading to catastrophic failure. The FE code Ansys was used for the analyses. 3D models were developed, loads were applied, and linear elastic static as well as buckling analyses were performed. The results obtained from analysis were in reasonable agreement with the experimental tests.

Zafar, Syed Shahrukh

434

Aerodynamic models for a Darrieus wind turbine  

NASA Astrophysics Data System (ADS)

Various models proposed for the aerodynamics of Darrieus wind turbines are reviewed. The magnitude of the L/D ratio for a Darrieus rotor blade is dependent on the profile, the Re, boundary layer characteristics, and the three-dimensional flow effects. The aerodynamic efficiency is theoretically the Betz limit, and the interference of one blade with another is constrained by the drag force integrated over all points on the actuator disk. A single streamtube model can predict the power available in a Darrieus, but the model lacks definition of the flow structure and the cyclic stresses. Techniques for calculating the velocity profiles and the consequent induced velocity at the blades are presented. The multiple streamtube theory has been devised to account for the repartition of the velocity in the rotor interior. The model has been expanded as the double multiple streamtube theory at Sandia Laboratories. Futher work is necessary, however, to include the effects of dynamic decoupling at high rotation speeds and to accurately describe blade behavior.

Fraunie, P.; Beguier, C.; Paraschivoiu, I.; Delclaux, F.

1982-11-01

435

a Mathematical Model for Wind Turbine Blades  

NASA Astrophysics Data System (ADS)

A mathematical model for an elastic wind turbine blade mounted on a rigid test stand is derived and compared with experimental results. The linear equations of motion describe small rotations of the test stand, blade lateral deflections and rotation of the chord. Warping, extension and tilt of the cross-sections are slaved to the dependent minimal co-ordinates in order to reduce the number of state variables. Using the principle of virtual work, a procedure is employed which combines the volume discretization of general “solid”, or shell-type finite elements (FE), with the approach of global form functions (stretching over the whole blade length). The equations of motion are solved as an eigenvalue problem and the results are compared with an experimental modal analysis of a 19 m long blade. The computed eigenfrequencies fit well, but the mathematical model underestimates the pitch motion of the blade chord. Parameter studies show the effect of warping. Despite the few degrees of freedom and uncertainties in the model parameters, the mathematical model approximates the measured blade dynamics well.

BAUMGART, A.

2002-03-01

436

Advanced wind turbine design studies: Advanced conceptual study. Final report  

SciTech Connect

In conjunction with the US Department of Energy and the National Renewable Energy Laboratory`s Advanced Wind Turbine Program, the Atlantic Orient Corporation developed preliminary designs for the next generation of wind turbines. These 50 kW and 350 kW turbines are based upon the concept of simplicity. By adhering to a design philosophy that emphasizes simplicity, we project that these turbines will produce energy at extremely competitive rates which will unlock the potential of wind energy domestically and internationally. The program consisted of three distinct phases. First, we evaluated the operational history of the Enertech 44 series wind turbines. As a result of this evaluation, we developed, in the second phase, a preliminary design for a new 50 kW turbine for the near-term market. In the third phase, we took a clean-sheet-of-paper approach to designing a 350 kW turbine focused on the mid-1990s utility market that incorporated past experience and advanced technology.

Hughes, P.; Sherwin, R. [Atlantic Orient Corp., Norwich, VT (United States)] [Atlantic Orient Corp., Norwich, VT (United States)

1994-08-01

437

Advanced wind turbine design studies: Advanced conceptual study  

NASA Astrophysics Data System (ADS)

In conjunction with the US Department of Energy and the National Renewable Energy Laboratory's Advanced Wind Turbine Program, the Atlantic Orient Corporation developed preliminary designs for the next generation of wind turbines. These 50 kW and 350 kW turbines are based upon the concept of simplicity. By adhering to a design philosophy that emphasizes simplicity, we project that these turbines will produce energy at extremely competitive rates which will unlock the potential of wind energy domestically and internationally. The program consisted of three distinct phases. First, we evaluated the operational history of the Enertech 44 series wind turbines. As a result of this evaluation, we developed, in the second phase, a preliminary design for a new 50 kW turbine for the near-term market. In the third phase, we took a clean-sheet-of-paper approach to designing a 350 kW turbine focused on the mid-1990s utility market that incorporated past experience and advanced technology.

Hughes, P.; Sherwin, R.

1994-08-01

438

Wind Turbine Blade Design System - Aerodynamic and Structural Analysis  

NASA Astrophysics Data System (ADS)

The ever increasing need for energy and the depletion of non-renewable energy resources has led to more advancement in the "Green Energy" field, including wind energy. An improvement in performance of a Wind Turbine will enhance its economic viability, which can be achieved by better aerodynamic designs. In the present study, a design system that has been under development for gas turbine turbomachinery has been modified for designing wind turbine blades. This is a very different approach for wind turbine blade design, but will allow it to benefit from the features inherent in the geometry flexibility and broad design space of the presented system. It starts with key overall design parameters and a low-fidelity model that is used to create the initial geometry parameters. The low-fidelity system includes the axisymmetric solver with loss models, T-Axi (Turbomachinery-AXIsymmetric), MISES blade-to-blade solver and 2D wing analysis code XFLR5. The geometry parameters are used to define sections along the span of the blade and connected to the CAD model of the wind turbine blade through CAPRI (Computational Analysis PRogramming Interface), a CAD neutral API that facilitates the use of parametric geometry definition with CAD. Either the sections or the CAD geometry is then available for CFD and Finite Element Analysis. The GE 1.5sle MW wind turbine and NERL NASA Phase VI wind turbine have been used as test cases. Details of the design system application are described, and the resulting wind turbine geometry and conditions are compared to the published results of the GE and NREL wind turbines. A 2D wing analysis code XFLR5, is used for to compare results from 2D analysis to blade-to-blade analysis and the 3D CFD analysis. This kind of comparison concludes that, from hub to 25% of the span blade to blade effects or the cascade effect has to be considered, from 25% to 75%, the blade acts as a 2d wing and from 75% to the tip 3D and tip effects have to be taken into account for design considerations. In addition, the benefits of this approach for wind turbine design and future efforts are discussed.

Dey, Soumitr

2011-12-01

439

Measurements on a wind turbine wake: 3D effects and bluff body vortex shedding  

NASA Astrophysics Data System (ADS)

The velocity field in the wake of a two-bladed wind turbine model (diameter 180 mm) has been studied under different conditions using a two-component hot wire. All three velocity components were measured both for the turbine rotor normal to the oncoming flow as well as with the turbine inclined to the freestream direction (the yaw angle was varied from 0° to 20°). The measurements showed, as expected, a wake rotation in the opposite direction to that of the turbine. A yawed turbine is found to clearly deflect the wake flow to the side, showing the potential of controlling the wake by yawing the turbine. An unexpected feature of the flow was that spectra from the time signals showed the appearance of a low-frequency fluctuation both in the wake and in the flow outside the wake. This fluctuation was found both with and without freestream turbulence and also with a yawed turbine. The frequency expressed as a Strouhal number was shown to be independent of the freestream velocity or turbulence level, but the low frequency was only observed when the tip speed ratio (or equivalently the drag coefficient) was high. The shedding frequency changed also with the yaw angle. This is in agreement with the idea that the turbine sheds structures as a bluff body. The phenomenon, noticeable in all the velocity components, was further investigated using two-point cross-correlations of the velocity signals. Copyright

Medici, D.; Alfredsson, P. H.

2006-05-01

440

Effects of structure flexibility on horizontal axis wind turbine performances  

NASA Astrophysics Data System (ADS)

This work illustrates the effects of flexibility of rotor blades and turbine tower on the performances of an horizontal axis wind turbine (HAWT) designed by our ADAG research group, by means of several example applied on a recent project for a active pitch controlled upwind 60 kW HAWT. The influence of structural flexibility for blade only, tower only and blade coupled with tower configuration is investigated using an aero-elastic computer-aided engineering (CAE) tool for horizontal axis wind turbines named FAST developed at National Renewable Energy Laboratory (NREL) of USA. For unsteady inflow conditions in front of the isolated HAWT the performances in rigid and flexible operation mode are computed and compared in order to illustrate the limitation included within a classical rigid body approach to wind turbine simulation.

Coiro, D. P.; Daniele, E.; Scherillo, F.

2013-10-01

441

Characterizing wind turbine system response to lightning activity  

SciTech Connect

A lightning protection research program was instituted by National Renewable Energy Laboratory to minimize lightning damage to wind turbines and to further the understanding of effective damage mitigation techniques. To that end, a test program is under way to observe lightning activity, protection system response, and damage at a wind power plant in the Department of Energy (DOE) and Electric Power Research Institute (EPRI) Turbine Verification Program. The authors installed Lightning activated surveillance cameras along with a special storm tracking device to observe the activity in the wind plant area. They instrumented the turbines with lightning and ground current detection devices to log direct and indirect strike activity at each unit. They installed a surge monitor on the utility interface to track incoming activity from the transmission lines. Maintenance logs are used to verify damage and determine downtime and repair costs. Actual strikes to turbines were recorded on video and ancillary devices. The test setup and some results are discussed in this paper.

McNiff, B.; LaWhite, N. [McNiff Light Industry, Harborside, ME (United States); Muljadi, E. [National Renewable Energy Lab., Golden, CO (United States)

1998-07-01

442

Optimization of Wind Turbine Airfoils/Blades and Wind Farm Layouts  

NASA Astrophysics Data System (ADS)

Shape optimization is widely used in the design of wind turbine blades. In this dissertation, a numerical optimization method called Genetic Algorithm (GA) is applied to address the shape optimization of wind turbine airfoils and blades. In recent years, the airfoil sections with blunt trailing edge (called flatback airfoils) have been proposed for the inboard regions of large wind-turbine blades because they provide several structural and aerodynamic performance advantages. The FX, DU and NACA 64 series airfoils are thick airfoils widely used for wind turbine blade application. They have several advantages in meeting the intrinsic requirements for wind turbines in terms of design point, off-design capabilities and structural properties. This research employ both single- and multi-objective genetic algorithms (SOGA and MOGA) for shape optimization of Flatback, FX, DU and NACA 64 series airfoils to achieve maximum lift and/or maximum lift to drag ratio. The commercially available software FLUENT is employed for calculation of the flow field using the Reynolds-Averaged Navier-Stokes (RANS) equations in conjunction with a two-equation Shear Stress Transport (SST) turbulence model and a three equation k-kl-o turbulence model. The optimization methodology is validated by an optimization study of subsonic and transonic airfoils (NACA0012 and RAE 2822 airfoils). In this dissertation, we employ DU 91-W2-250, FX 66-S196-V1, NACA 64421, and Flat-back series of airfoils (FB-3500-0050, FB-3500-0875, and FB-3500-1750) and compare their performance with S809 airfoil used in NREL Phase II and III wind turbines; the lift and drag coefficient data for these airfoils sections are available. The output power of the turbine is calculated using these airfoil section blades for a given B and lambda and is compared with the original NREL Phase II and Phase III turbines using S809 airfoil section. It is shown that by a suitable choice of airfoil section of HAWT blade, the power generated by the turbine can be significantly increased. Parametric studies are also conducted by varying the turbine diameter. In addition, a simplified dynamic inflow model is integrated into the BEM theory. It is shown that the improved BEM theory has superior performance in capturing the instantaneous behavior of wind turbines due to the existence of wind turbine wake or temporal variations in wind velocity. The dissertation also considers the Wind Farm layout optimization problem using a genetic algorithm. Both the Horizontal --Axis Wind Turbines (HAWT) and Vertical-Axis Wind Turbines (VAWT) are considered. The goal of the optimization problem is to optimally position the turbines within the wind farm such that the wake effects are minimized and the power production is maximized. The reasonably accurate modeling of the turbine wake is critical in determination of the optimal layout of the turbines and the power generated. For HAWT, two wake models are considered; both are found to give similar answers. For VAWT, a very simple wake model is employed. Finally, some preliminary investigation of shape optimization of 3D wind turbine blades at low Reynolds numbers is conducted. The optimization employs a 3D straight untapered wind turbine blade with cross section of NACA 0012 airfoils as the geometry of baseline blade. The optimization objective is to achieve maximum Cl/Cd as well as maximum Cl. The multi-objective genetic algorithm is employed together with the commercially available software FLUENT for calculation of the flow field using the Reynolds-Averaged Navier-Stokes (RANS) equations in conjunction with a one-equation Sparlart-Allmaras turbulence model. The results show excellent performance of the optimized wind turbine blade and indicate the feasibility of optimization on real wind turbine blades with more complex shapes in the future. (Abstract shortened by UMI.)

Chen, Xiaomin

443

Analytical expressions for maximum wind turbine average power in a Rayleigh wind regime  

SciTech Connect

Average or expectation values for annual power of a wind turbine in a Rayleigh wind regime are calculated and plotted as a function of cut-out wind speed. This wind speed is expressed in multiples of the annual average wind speed at the turbine installation site. To provide a common basis for comparison of all real and imagined turbines, the Rayleigh-Betz wind machine is postulated. This machine is an ideal wind machine operating with the ideal Betz power coefficient of 0.593 in a Rayleigh probability wind regime. All other average annual powers are expressed in fractions of that power. Cases considered include: (1) an ideal machine with finite power and finite cutout speed, (2) real machines operating in variable speed mode at their maximum power coefficient, and (3) real machines operating at constant speed.

Carlin, P.W.

1996-12-01

444

Health effects and wind turbines: A review of the literature  

PubMed Central

Background Wind power has been harnessed as a source of power around the world. Debate is ongoing with respect to the relationship between reported health effects and wind turbines, specifically in terms of audible and inaudible noise. As a result, minimum setback distances have been established world-wide to reduce or avoid potential complaints from, or potential effects to, people living in proximity to wind turbines. People interested in this debate turn to two sources of information to make informed decisions: scientific peer-reviewed studies published in scientific journals and the popular literature and internet. Methods The purpose of this paper is to review the peer-reviewed scientific literature, government agency reports, and the most prominent information found in the popular literature. Combinations of key words were entered into the Thomson Reuters Web of KnowledgeSM and the internet search engine Google. The review was conducted in the spirit of the evaluation process outlined in the Cochrane Handbook for Systematic Reviews of Interventions. Results Conclusions of the peer reviewed literature differ in some ways from those in the popular literature. In peer reviewed studies, wind turbine annoyance has been statistically associated with wind turbine noise, but found to be more strongly related to visual impact, attitude to wind turbines and sensitivity to noise. To date, no peer reviewed articles demonstrate a direct causal link between people living in proximity to modern wind turbines, the noise they emit and resulting physiological health effects. If anything, reported health effects are likely attributed to a number of environmental stressors that result in an annoyed/stressed state in a segment of the population. In the popular literature, self-reported health outcomes are related to distance from turbines and the claim is made that infrasound is the causative factor for the reported effects, even though sound pressure levels are not measured. Conclusions What both types of studies have in common is the conclusion that wind turbines can be a source of annoyance for some people. The difference between both types is the reason for annoyance. While it is acknowledged that noise from wind turbines can be annoying to some and associated with some reported health effects (e.g., sleep disturbance), especially when found at sound pressure levels greater than 40 db(A), given that annoyance appears to be more strongly related to visual cues and attitude than to noise itself, self reported health effects of people living near wind turbines are more likely attributed to physical manifestation from an annoyed state than from wind turbines themselves. In other words, it appears that it is the change in the environment that is associated with reported health effects and not a turbine-specific variable like audible noise or infrasound. Regardless of its cause, a certain level of annoyance in a population can be expected (as with any number of projects that change the local environment) and the acceptable level is a policy decision to be made by elected officials and their government representatives where the benefits of wind power are weighted against their cons. Assessing the effects of wind turbines on human health is an emerging field and conducting further research into the effects of wind turbines (and environmental changes) on human health, emotional and physical, is warranted. PMID:21914211

2011-01-01

445

Review of Wind Turbine Wake Models and Future Directions (Presentation)  

SciTech Connect

This presentation gives a brief overview to wind turbine wake modeling, ranging from models used in the 1980s up to the present. The presentation shows the strengths and weaknesses of various models and discusses the needs of the wind energy industry and research sectors. Both power production and loads analysis are discussed.

Churchfield, M. J.

2013-08-01

446

Danehy Park Wind Turbine Project Preliminary Assessment Report  

E-print Network

Danehy Park Wind Turbine Project Preliminary Assessment Report Danehy Park Project Group Wind Energy Projects in Action (WEPA) Massachusetts Institute of Technology Cy Chan Project Lead, Resource, Jack Clarke and Jean Rogers for their guidance with the environmental and community impact assessment

447

Vibration and Structural Response of Hybrid Wind Turbine Blades  

E-print Network

sources. Wind energy is capable of providing 72 TW (TW = 10^12 W) of electric power, which is approximately four and half times the world energy consumption of 15.8 TW as reported in 2006. Since power output extracted from wind turbines is proportional...

Nanami, Norimichi

2011-02-22

448

Application of a genetic algorithm to wind turbine design  

Microsoft Academic Search

This paper presents an optimization method for stall-regulated horizontal-axis wind turbines. A hybrid approach is used that combines the advantages of a genetic algorithm with an inverse design method. This method is used to determine the optimum blade pitch and blade chord and twist distributions that maximize the annual energy production. To illustrate the method, a family of 25 wind

M. S. Selig; V. L. Coverstone-Carroll

1996-01-01

449

The economic optimisation of horizontal axis wind turbine design  

Microsoft Academic Search

A method for determining the optimum design parameters for horizontal axis wind turbines was developed and tested. These design parameters were the rotor diameter, rated power and tower height. The optimum values were found to be dependent on site wind regime. The results of the study indicated that it was, however, only the optimisation of the relative combination of rotor

G. R. Collecutt; R. G. J. Flay

1996-01-01

450

Optimizing the NW off-shore wind turbine design  

Microsoft Academic Search

This paper provides a solution to address one of the requirements identified in the US Northwest 6th Power Plan, specifically, meeting an increase in the forecasted Pacific Northwest demand with renewable generation. A model is presented which evaluates one source of renewable generation, off-shore wind energy. The model analyzes different wind turbine design characteristics, assigns significance to potential synergistic effects

Tugrul U. Daim; Elvan Bayraktaroglu; Judith Estep; Dong Joon Lim; Jubin Upadhyay; Jiting Yang

451

Reliable, Lightweight Transmissions For Off-Shore, Utility Scale Wind Turbines  

SciTech Connect

The objective of this project was to reduce the technical risk for a hydrostatic transmission based drivetrain for high-power utility-size wind turbines. A theoretical study has been performed to validate the reduction of cost of energy (CoE) for the wind turbine, identify risk mitigation strategies for the drive system and critical components, namely the pump, shaft connection and hydrostatic transmission (HST) controls and address additional benefits such as reduced deployment costs, improved torque density and improved mean time between repairs (MTBR).

Jean-Claude Ossyra

2012-10-25

452

Dynamic Characteristic of the Drive Train of DFIG Wind Turbines during Grid Faults  

Microsoft Academic Search

During a grid voltage drop, a problem is resonances in the drive-train shaft between the wind turbine and induction generator. Disadvantageous effects caused by this are noticeable vibrations and high mechanical stresses due to torque oscillations. The oscillations can be damped using the drive train damper, which is used to mitigate fatigue loading of drive train components, controller consisting of

Yao Xingjia; Liang Lizhe; Xing Zuoxia

2009-01-01

453

Robust Gain Scheduling Controller for Pitch Regulated Variable Speed Wind Turbine  

Microsoft Academic Search

The paper deals with the design of a control system for a variable-speed pitch-regulated wind turbine. The control objectives of such system are mostly to ensure a good energy conversion performances and to reduce the mechanical stresses of the plant components. For the different operating areas of the plant, the non linear behavior of the system is described by a

Fabien Lescher; Jing Yun Zhao; Pierre Borne

2005-01-01

454

Model OA Wind Turbine Generator FEMA (Failure Modes and Effects Analysis)  

Microsoft Academic Search

This report presents the results of Failure Modes and Effects Analysis (FMEA) conducted for the Wind Turbine Generators. The FMEA was performed for the functional modes of each system, subsystem, or component. The single-point failures were eliminated for most of the systems. The blade system was the only exception. The qualitative probability of a blade separating was estimated at Level

W. E. Klein; V. R. Lalli

1989-01-01

455

Cold Weather Wind Turbines: A Joint NASA/NSF/DOE Effort in Technology Transfer and Commercialization  

NASA Technical Reports Server (NTRS)

Renewable energy sources and their integration with other power sources to support remote communities is of interest for Mars applications as well as Earth communities. The National Science Foundation (NSF), NASA, and the Department of Energy (DOE) have been jointly supporting development of a 100 kW cold weather wind turbine through grants and SBIRs independently managed by each agency but coordinated by NASA. The NSF grant addressed issues associated with the South Pole application and a 3 kW direct drive unit is being tested there in anticipation of the 100 kW unit operation. The DOE-NREL contract focused on development of the 100 kW direct drive generator. The NASA SBIR focused on the development of the 100 kW direct drive wind turbine. The success of this effort has required coordination and team involvement of federal agencies and the industrial partners. Designs of the wind turbine and component performance testing results will be presented. Plans for field testing of wind turbines, based on this design, in village energy systems in Alaska and in energy production at the South Pole Station will be discussed. Also included will be a discussion of terrestrial and space use of hybrid energy systems, including renewable energy sources, such as the wind turbine, to support remote communities.

Flynn, Michael; Bubenheim, David; Chiang, Erick; Goldman, Peter; Kohout, Lisa; Norton, Gary; Kliss, Mark (Technical Monitor)

1997-01-01

456

Structural Load Analysis of a Wind Turbine under Pitch Actuator and Controller Faults  

NASA Astrophysics Data System (ADS)

In this paper, we investigate the characteristics of a wind turbine under blade pitch angle and shaft speed sensor faults as well as pitch actuator faults. A land-based NREL 5MW variable speed pitch reg- ulated wind turbine is considered as a reference. The conventional collective blade pitch angle controller strategy with independent pitch actuators control is used for load reduction. The wind turbine class is IEC-BII. The main purpose is to investigate the severity of end effects on structural loads and responses and consequently identify the high-risk components according to the type and amplitude of fault using a servo-aero-elastic simulation code, HAWC2. Both transient and steady state effects of faults are studied. Such information is useful for wind turbine fault detection and identification as well as system reliability analysis. Results show the effects of faults on wind turbine power output and responses. Pitch sensor faults mainly affects the vibration of shaft main bearing, while generator power and aerodynamic thrust are not changed significantly, due to independent pitch actuator control of three blades. Shaft speed sensor faults can seriously affect the generator power and aerodynamic thrust. Pitch actuator faults can result in fully pitching of the blade, and consequently rotor stops due to negative aerodynamic torque.

Etemaddar, Mahmoud; Gao, Zhen; Moan, Torgeir

2014-12-01

457

Effect of Geometric Uncertainties on the Aerodynamic Characteristic of Offshore Wind Turbine Blades  

NASA Astrophysics Data System (ADS)

Offshore wind turbines operate in a complex unsteady flow environment which causes unsteady aerodynamic loads. The unsteady flow environment is characterized by a high degree of uncertainty. In addition, geometry variations and material imperfections also cause uncertainties in the design process. Probabilistic design methods consider these uncertainties in order to reach acceptable reliability and safety levels for offshore wind turbines. Variations of the rotor blade geometry influence the aerodynamic loads which also affect the reliability of other wind turbine components. Therefore, the present paper is dealing with geometric uncertainties of the rotor blades. These can arise from manufacturing tolerances and operational wear of the blades. First, the effect of geometry variations of wind turbine airfoils on the lift and drag coefficients are investigated using a Latin hypercube sampling. Then, the resulting effects on the performance and the blade loads of an offshore wind turbine are analyzed. The variations of the airfoil geometry lead to a significant scatter of the lift and drag coefficients which also affects the damage-equivalent flapwise bending moments. In contrast to that, the effects on the power and the annual energy production are almost negligible with regard to the assumptions made.

Ernst, Benedikt; Schmitt, Henning; Seume, Jörg R.

2014-12-01

458

The 100 kW experimental wind turbine generator project  

NASA Technical Reports Server (NTRS)

The Energy Research and Development Administration and the NASA Lewis Research Center engaged jointly in a Wind Energy Program which included the design and erection of a 100 kW wind turbine generator. This test machine consists of a rotor turbine, transmission, shaft, alternator, and tower. The rotor, measuring 125 feet in diameter and consisting of two variable pitch blades, operates at 40 rpm and generates 100 kW of electrical power at a wind velocity of 18 mph. The entire assembly is placed on top of a tower 100 feet above ground level. The machine was scheduled to be ready for operation in August, 1975.

Puthoff, R. L.; Sirocky, P.

1975-01-01

459

Fuzzy regulator design for wind turbine yaw control.  

PubMed

This paper proposes the development of an advanced fuzzy logic controller which aims to perform intelligent automatic control of the yaw movement of wind turbines. The specific fuzzy controller takes into account both the wind velocity and the acceptable yaw error correlation in order to achieve maximum performance efficacy. In this way, the proposed yaw control system is remarkably adaptive to the existing conditions. In this way, the wind turbine is enabled to retain its power output close to its nominal value and at the same time preserve its yaw system from pointless movement. Thorough simulation tests evaluate the proposed system effectiveness. PMID:24693237

Theodoropoulos, Stefanos; Kandris, Dionisis; Samarakou, Maria; Koulouras, Grigorios

2014-01-01

460

Variable Speed Wind Turbine Generator with Zero-sequence Filter  

DOEpatents

A variable speed wind turbine generator system to convert mechanical power into electrical power or energy and to recover the electrical power or energy in the form of three phase alternating current and return the power or energy to a utility or other load with single phase sinusoidal waveform at sixty (60) hertz and unity power factor includes an excitation controller for generating three phase commanded current, a generator, and a zero sequence filter. Each commanded current signal includes two components: a positive sequence variable frequency current signal to provide the balanced three phase excitation currents required in the stator windings of the generator to generate the rotating magnetic field needed to recover an optimum level of real power from the generator; and a zero frequency sixty (60) hertz current signal to allow the real power generated by the generator to be supplied to the utility. The positive sequence current signals are balanced three phase signals and are prevented from entering the utility by the zero sequence filter. The zero sequence current signals have zero phase displacement from each other and are prevented from entering the generator by the star connected stator windings. The zero sequence filter allows the zero sequence current signals to pass through to deliver power to the utility.

Muljadi, Eduard (Golden, CO)

1998-08-25