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1

Fatigue reliability of wind turbine components  

Microsoft Academic Search

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

P. S. Veers

1990-01-01

2

A stochastic DEVS wind turbine component model for wind farm simulation  

Microsoft Academic Search

Wind farms use several wind turbines to generate electricity and provide a renewable source of energy. However, due to large forces as a result of hourly and seasonal variations in wind speed and direction, wind turbines experience stochastic loading that often lead to failures of wind turbine components such as the gearbox and generator. Wind turbine failures result in costly

Eduardo Pérez; Lewis Ntaimo; Eunshin Byon; Yu Ding

2010-01-01

3

Fatigue reliability of wind turbine components  

SciTech Connect

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. 5 refs., 9 figs., 1 tab.

Veers, P.S.

1990-01-01

4

Modal analysis of pre-loaded wind turbine structural components  

Microsoft Academic Search

The modal behaviour of wind turbine support structures can be assessed using the techniques of Rayleigh [10] and Stodola [11]. Guyed wind turbines are lighter and therefore cheaper than free-standing ones. Guyed structures are in a permanent state of stress due to the pre-tension in the cables. Further, wind turbines are subject to a large horizontal force during normal generation

M. Johnston; J. W. Twidell; G. M. Chapman

1998-01-01

5

75 FR 2159 - In the Matter of Certain Variable Speed Wind Turbines and Components Thereof; Termination of...  

Federal Register 2010, 2011, 2012, 2013

...337-TA-641] In the Matter of Certain Variable Speed Wind Turbines and Components Thereof; Termination of Investigation With...United States after importation of certain variable speed wind turbines and components thereof that infringe claims 121-125 of...

2010-01-14

6

Multi-component wind measurements of wind turbine wakes performed with three LiDARs  

NASA Astrophysics Data System (ADS)

Field measurements of the wake flow produced from the interaction between atmospheric boundary layer and a wind turbine are performed with three wind LiDARs. The tested wind turbine is a 2 MW Enercon E-70 located in Collonges, Switzerland. First, accuracy of mean values and frequency resolution of the wind measurements are surveyed as a function of the number of laser rays emitted for each measurement. Indeed, measurements performed with one single ray allow maximizing sampling frequency, thus characterizing wake turbulence. On the other hand, if the number of emitted rays is increased accuracy of mean wind is increased due to the longer sampling period. Subsequently, two-dimensional measurements with a single LiDAR are carried out over vertical sections of the wind turbine wake and mean wake flow is obtained by averaging 2D measurements consecutively performed. The high spatial resolution of the used LiDAR allows characterizing in details velocity defect present in the central part of the wake and its downstream recovery. Single LiDAR measurements are also performed by staring the laser beam at fixed directions for a sampling period of about ten minutes and maximizing the sampling frequency in order to characterize wake turbulence. From these tests wind fluctuation peaks are detected in the wind turbine wake at blade top-tip height for different downstream locations. The magnitude of these turbulence peaks is generally reduced by moving downstream. This increased turbulence level at blade top-tip height observed for a real wind turbine has been already detected from previous wind tunnel tests and Large Eddy simulations, thus confirming the presence of a source of dangerous fatigue loads for following wind turbines within a wind farm. Furthermore, the proper characterization of wind fluctuations through LiDAR measurements is proved by the detection of the inertial subrange from spectral analysis of these velocity signals. Finally, simultaneous measurements with two LiDARs are performed over the mean vertical symmetry plane of the wind turbine wake, while a third LiDAR measures the incoming wind over a vertical plane parallel to the mean wind direction and lying outside of the wake. One LiDAR is placed in proximity of the wind turbine location and measures pointing downstream, whereas a second LiDAR is located along the mean wind direction at a downstream distance of 6.5 diameters and measures pointing upstream. For these measurements axial and vertical velocity components are retrieved only for measurement points where the two laser beams result to be roughly orthogonal. Statistics of the two velocity components show in the near wake at hub height strong flow fluctuations with magnitudes about 30% of the mean value, and a gradual reduction for downstream distances larger than three rotor diameters.

Iungo, G. V.; Wu, Y.-T.; Porté-Agel, F.

2012-04-01

7

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

Microsoft Academic Search

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

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

1994-01-01

8

Wind turbine  

Microsoft Academic Search

A wind turbine of the type having an airfoil blade mounted on a flexible beam and a pitch governor which selectively, torsionally twists the flexible beam in response to wind turbine speed thereby setting blade pitch, is provided with a limiter which restricts unwanted pitch change at operating speeds due to torsional creep of the flexible beam. The limiter allows

1982-01-01

9

Wind turbine  

Microsoft Academic Search

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

Marvin C

1982-01-01

10

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

11

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

Microsoft Academic Search

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

N. D. Kelley

1994-01-01

12

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

13

Wind turbine  

SciTech Connect

A wind turbine of the type having an airfoil blade mounted on a flexible beam and a pitch governor which selectively, torsionally twists the flexible beam in response to wind turbine speed thereby setting blade pitch, is provided with a limiter 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 which responds to changing rotor speed by pivotal movement, the limiter comprising a resilient member which engages an end of the pendulum to restrict further movement thereof, and in turn restrict beam creep and unwanted blade pitch misadjustment.

Cheney, M.C.

1982-10-05

14

Wind turbine acoustics  

NASA Astrophysics Data System (ADS)

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.

1990-12-01

15

The effects of variable speed and drive train component efficiencies on wind turbine energy capture  

SciTech Connect

A wind turbine rotor achieves optimal aerodynamic efficiency at a single tip-speed ratio (TSR). To maintain that optimal TSR and maximize energy capture in the stochastic wind environment, it is necessary to employ variable-speed operation. Conventional constant-speed wind turbines have, in the past, been converted into variable-speed turbines by attaching power electronics to the conventional induction generator and gearbox drive train. Such turbines have shown marginal, if any, improvement in energy capture over their constant-speed counterparts. These discrepancies have been shown to be the result of drive train components that are not optimized for variable-speed operation. Traditional drive trains and power electronic converters are designed to achieve maximum efficiency at full load and speed. However, the main energy producing winds operate the turbine at light load for long periods of time. Because of this, significant losses to efficiency occur. This investigation employs a quasi-static model to demonstrate the dramatic effect that component efficiency curves can have on overall annual energy capture.

Fingersh, L.J.; Robinson, M.C.

1998-05-01

16

Reliability of Wind Turbine components — Solder elements fatigue failure  

Microsoft Academic Search

The physics of failure for electrical components due to temperature loading is described. The main focus is on crack propagation in solder joints and damage accumulation models based on the Miner's rule. Two models are proposed that describe the initial accumulated plastic strain depending on the temperature mean and temperature range. Constant terms and model errors are estimated. The proposed

Erik E. Kostandyan; John D. Sorensen

2012-01-01

17

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

18

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

NASA Astrophysics Data System (ADS)

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

19

225-kW Dynamometer for Testing Small Wind Turbine Components (Poster)  

SciTech Connect

The National Wind Technology Center at NREL has commissioned a 225-kW dynamometer to facilitate the development of advanced generators, gearboxes, and power electronics to reduce the cost and improve the reliability of small wind turbines.

Green, J.

2006-01-01

20

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

21

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

Microsoft Academic Search

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

WUBTERSTEUBMSTEVEB R; PAUL S. VEERS

2000-01-01

22

A component mode synthesis algorithm for multibody dynamics of wind turbines  

NASA Astrophysics Data System (ADS)

A system reduction scheme related to a multibody formulation of wind turbine dynamics is devised. Each substructure is described in its own frame of reference, which is moving freely in the vicinity of the moving substructure, in principle without any constraints to the rigid body part of the motion of the substructure. The system reduction is based on a component mode synthesis method, where the response of the internal degrees of freedom of the substructure is described as the quasi-static response induced by the boundary degrees of freedom via the constraint modes superimposed in combination to a dynamic component induced by inertial effects and internal loads. The latter component is modelled by a truncated modal expansion in fixed interface undamped eigenmodes. The selected modal vector base for the internal dynamics ensures that the boundary degrees of freedom account for the rigid-body dynamics of the substructure, and explicitly represent the coupling degrees of freedom at the interface to the adjacent substructures. The method has been demonstrated for a blade structure, which has been modelled as two substructures. Two modelling methods have been examined where the first is by use of fixed-fixed eigenmodes for the innermost substructure and fixed-free eigenmodes for the outermost substructure. The other approach is by use of fixed-free eigenmodes for both substructures. The fixed-fixed method shows good correspondence with the full FE model which is not the case for the fixed-free method due to incompatible displacements and rotations at the interface between the two substructures. Moreover, the results from the reduced model by use of constant constraint modes and constant fixed interface modes over a large operating area for the wind turbine blade are almost identical to the full FE model.

Holm-Jørgensen, K.; Nielsen, S. R. K.

2009-10-01

23

Small Wind Turbine Testing and Applications Development  

SciTech Connect

Small wind turbines offer a promising alternative for many remote electrical uses where there is a good wind resource. The National Wind Technology Center (NWTC) of the National Renewable Energy Laboratory helps further the role that small turbines can play in supplying remote power needs. The NWTC tests and develops new applications for small turbines. The NWTC also develops components used in conjunction with wind turbines for various applications. This paper describes wind energy research at the NWTC for applications including battery charging stations, water desalination/purification, and health clinics. Development of data acquisition systems and tests on small turbines are also described.

Corbus, D.; Baring-Gould, I.; Drouilhet, S.; Gevorgian, V.; Jimenez, T.; Newcomb, C.; Flowers, L.

1999-09-14

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

Wind Turbine Technology  

SciTech Connect

This book reviews advances in aerodynamics, structural dynamics and fatigue, wind characteristics, acoustic and electromagnetic emissions, commercial wind power applications, and utility power systems that use wind power plants. The book examines the choices made by inventors, designers, and builders of turbines; absorb their practical lessons; and presents the experience of a wide range of wind-energy professionals. Included are sources of technical information, side-by-side comparisons of commercial wind turbines, technical data on wind turbines of various sizes and types, and fundamental equations for engineers designing and analyzing systems. This book would be useful to practicing engineers, designers, meteorologists, researchers, utility project managers and planners, wind power plant developers, and equipment manufacturers, as well as students and teachers.

Spera, D.A. (ed.)

1994-01-01

26

Aeroacoustics of large wind turbines  

Microsoft Academic Search

This paper reviews published information on aerodynamically generated noise from large horizontal axis wind turbines operated for electric power generation. Methods are presented for predicting both the discrete frequency rotational noise components and the broadband noise components, and results are compared with measurements. Refraction effects that result in the formation of high-frequency shadow zones in the upwind direction and channeling

Harvey H. Hubbard; Kevin P. Shepherd

1991-01-01

27

Direct Drive Wind Turbine.  

National Technical Information Service (NTIS)

A wind turbine is provided that minimizes the size of the drive train and nacelle while maintaining the power electronics and transformer at the top of the tower. The turbine includes a direct drive generator having an integrated disk brake positioned rad...

C. Bevington D. Costin G. Bywaters J. Stowell W. Banforth

2004-01-01

28

Superconducting wind turbine generators  

Microsoft Academic Search

We have examined the potential of 10 MW superconducting direct drive generators to enter the European offshore wind power market and estimated that the production of about 1200 superconducting turbines until 2030 would correspond to 10% of the EU offshore market. The expected properties of future offshore turbines of 8 and 10 MW have been determined from an up-scaling of

A. B. Abrahamsen; N. Mijatovic; E. Seiler; T. Zirngibl; C. Træholt; P. B. Nørgård; N. F. Pedersen; N. H. Andersen; J. Østergård

2010-01-01

29

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

30

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

31

Wind turbine system  

SciTech Connect

A wind turbine system utilizes a bicycle wheel type turbine having airfoils mounted on various spoke pairs. The vertical yaw axis lies in the horizontal projection of the airfoils to offer better control of the system; for example, automatic stowage in the case of excessive wind is provided since the superstructure of the turbine provides a torque around the vertical yaw axis which moves the wheel into a stowed position. At the same time, the wheel diameter can be made larger and thus heavier since the drive connection to the generator also helps support the weight of the wheel, since it is a rim drive. Greater electrical generation is also provided since an air scoop facing into the wind allows the effective generator capacity to be increased with air velocity. Lastly, the radial rate of change of the angle of the airfoils can be closely controlled.

Smith, O.J.

1982-05-18

32

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

33

Wind turbine rotor  

Microsoft Academic Search

A fixed pitch wind turbine rotor is teeter mounted onto a low speed input shaft which is connected to the input of a step-up transmission. The output of the transmission is connected to a rotary pole amplitude modulated induction machine which is operable as a generator at a plurality of discreet speeds of rotation and is also operable as a

J. M. Baskin; G. E. Miller; W. Wiesner

1985-01-01

34

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

35

Fatigue and reliability analyses for wind turbines  

Microsoft Academic Search

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

H. J. Sutherland

1992-01-01

36

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

37

Stability Simulation of Wind Turbine Systems  

Microsoft Academic Search

A simulation and digital computer modeling effort is described in which a wind turbine-generator system is adapted for stability evaluation using a large scale transient stability computer program. Component models of the MOD-2 wind generator system are described and their digital model equations are provided. A versatile wind velocity model is described, which provides the capability of simulating a wide

P. M. Anderson; Anjan Bose

1983-01-01

38

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

39

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

40

Smart structure for small wind turbine blade  

NASA Astrophysics Data System (ADS)

Wind energy is seen as a viable alternative energy option for future energy demand. The blades of wind turbines are generally regarded as the most critical component of the wind turbine system. Ultimately, the blades act as the prime mover of the whole system which interacts with the wind flow during the production of energy. During wind turbine operation the wind loading cause the deflection of the wind turbine blade which can be significant and affect the turbine efficiency. Such a deflection in wind blade not only will result in lower performance in electrical power generation but also increase of material degradation due high fatigue life and can significantly shorten the longevity for the wind turbine material. In harnessing stiffness of the blade will contribute massive weight factor and consequently excessive bending moment. To overcome this excessive deflection due to wind loading on the blade, it is feasible to use shape memory alloy (SMA) wires which has ability take the blade back to its optimal operational shape. This paper details analytical and experimental work being carried out to minimize blade flapping deflection using SMA.

Supeni, E. E.; Epaarachchi, J. A.; Islam, M. M.; Lau, K. T.

2013-08-01

41

Wind turbine acoustic standards  

NASA Astrophysics Data System (ADS)

A program is being conducted to develop noise standards for wind turbines which minimize annoyance and which can be used to design specifications. The approach consists of presenting wind turbine noise stimuli to test subjects in a laboratory listening chamber. The responses of the subjects are recorded for a range of stimuli which encompass the designs, operating conditions, and ambient noise levels of current and future installations. Results to date have established the threshold of detectability for a range of impulsive stimuli of the type associated with blade/tower wake interactions. The status of the ongoing psychoacoustic tests, the subjective data, and the approach to the development of acoustic criteria/standards are described.

Stephens, D. G.; Shepherd, K. P.; Grosveld, F.

1981-05-01

42

Optimum propeller wind turbines  

SciTech Connect

The Prandtl-Betz-Theodorsen theory of heavily loaded airscrews has been adapted to the design of propeller windmills which are to be optimized for maximum power coefficient. It is shown that the simpler, light-loading, constant-area wake assumption can generate significantly different ''optimum'' performance and geometry, and that it is therefore not appropriate to the design of propeller wind turbines when operating in their normal range of high-tip-speed-to-wind-speed ratio. Design curves for optimum power coefficient are presented and an example of the design of a typical two-blade optimum rotor is given.

Sanderson, R.J.; Archer, R.D.

1983-11-01

43

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

44

Vertical axis wind turbine  

Microsoft Academic Search

A vertical axis wind turbine is provided based on the co-pending application ser. No. 890,998, filed Mar. 28, 1978, now U.S. Pat. No. 4,204,805. In this improved system the centrifugal forces of rotation produce no bending moments in the air foil spars. Also, the center of mass, the center of useful aerodynamic pressure and the center of main bearing supported

Bolie

1981-01-01

45

Small Wind Turbine Technology Assessment.  

National Technical Information Service (NTIS)

The result of the study carried out under the scope of the ATYCA project Test Plant of Wind Systems for Isolated Applications, about the state of art of the small wind turbine technology (wind turbines with swept area smaller than 40 m''2) is presented. T...

F. Avia Aranda I. Cruz Cruz

1999-01-01

46

Wind response characteristics of horizontal axis wind turbines  

NASA Astrophysics Data System (ADS)

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.

1981-05-01

47

Wind turbine-generator  

SciTech Connect

A wind-turbine generator system is described which transforms the rotational energy of a wind driven turbine blade into rotation in opposite directions of a rotor and a stator of a dynamoelectric machine to generate electrical power. A bevel gear rotating with the turbine blade drives two pinion gears and associated concentric shafts in opposite directions. The two shafts combine with a planetary gear set to provide the desired oppositely directed rotation. One of the shafts is associated with a ring carrier and drives a ring gear in one rotational direction. The other shaft drives a planet carrier in the opposite rotational direction. The planetary gear set is arranged such that a sun gear is driven in the direction opposite to that of the ring gear. A rotor is affixed to the sun gear by a spider support structure, and a stator, affixed to rotate with the ring gear, surrounds the rotor. The rotor and stator are thus rotated in opposite, mechanically and electrically additive, directions.

Kirschbaum, H.S.

1981-09-22

48

Towers for Offshore Wind Turbines  

NASA Astrophysics Data System (ADS)

Increasing energy demand coupled with pollution free production of energy has found a viable solution in wind energy. Land based windmills have been utilized for power generation for more than two thousand years. In modern times wind generated power has become popular in many countries. Offshore wind turbines are being used in a number of countries to tap the energy from wind over the oceans and convert to electric energy. The advantages of offshore wind turbines as compared to land are that offshore winds flow at higher speed than onshore winds and the more available space. In some land based settings, for better efficiency, turbines are separated as much as 10 rotor diameters from each other. In offshore applications where only two wind directions are likely to predominate, the distances between the turbines arranged in a line can be shortened to as little as two or four rotor diameters. Today, more than a dozen offshore European wind facilities with turbine ratings of 450 kw to 3.6 MW exist offshore in very shallow waters of 5 to 12 m. Compared to onshore wind turbines, offshore wind turbines are bigger and the tower height in offshore are in the range of 60 to 80 m. The water depths in oceans where offshore turbines can be located are within 30 m. However as the distance from land increases, the costs of building and maintaining the turbines and transmitting the power back to shore also increase sharply. The objective of this paper is to review the parameters of design for the maximum efficiency of offshore wind turbines and to develop types offshore towers to support the wind turbines. The methodology of design of offshore towers to support the wind turbine would be given and the environmental loads for the design of the towers would be calculated for specific cases. The marine corrosion on the towers and the methods to control the corrosion also would be briefly presented. As the wind speeds tend to increase with distance from the shore, turbines build father offshore will be able to capture more wind energy. Currently two types of towers are considered. Cylindrical tubular structures and truss type structures. But truss type structures have less weight and flexibility in design. The construction of the offshore towers to harness the wind energy is also presented. The results will include the calculation of wind and wave forces on the tower and the design details for the tower.

Kurian, V. J.; Narayanan, S. P.; Ganapathy, C.

2010-06-01

49

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

50

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

51

Blade pitch angle control for a wind turbine generator  

Microsoft Academic Search

A blade pitch angle control for a wind turbine-generator establishing an optimum power or torque reference signal which, when operating conditions so warrant, is not limited by the nominal torque or power ratings of various turbine generator components. The reference signal is indicative of a maximum blade angle setting for safe operation of the wind turbine. An integral or lag

K. I. Harner; J. M. Kos; J. P. Patrick

1982-01-01

52

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

53

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

54

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

55

Towers for Offshore Wind Turbines  

Microsoft Academic Search

Increasing energy demand coupled with pollution free production of energy has found a viable solution in wind energy. Land based windmills have been utilized for power generation for more than two thousand years. In modern times wind generated power has become popular in many countries. Offshore wind turbines are being used in a number of countries to tap the energy

V. J. Kurian; S. P. Narayanan; C. Ganapathy

2010-01-01

56

Wind turbines and environment management  

NASA Astrophysics Data System (ADS)

The environment protection and management aspects of small and large scale wind turbines are examined. Legal aspects on municipal level are discussed. The relation with regional and national management is illustrated by investigations for a planned wind energy park. It is argued that because of environment effects and long term management procedures, the establishment of wind energy generators causes many problems.

Vaneck, P.; Koekebakker, P.

1983-05-01

57

Using of Composite Material in Wind Turbine Blades  

Microsoft Academic Search

The turbines manufactured from the mid 1980s until the late 1990s were mainly constructed using standard components. After that period, special components started being designed and manufactured for turbine use only. One of the best solutions is using composite materials in wind turbine. Most composites are made up of just two materials. One material (the matrix or binder) binds together

Bulent Eker; Aysegul Akdogan; Ali Vardar

2006-01-01

58

Rotationally sampled wind and MOD-2 wind turbine response  

NASA Astrophysics Data System (ADS)

In an effort to learn more about how wind behaves near wind turbines, researchers rotationally sampled winds by attaching sensors to the blades of a MOD-2 wind turbine. This fieldwork demonstrates the feasibility of a blade-mounted measuring technique and provides new data on the winds encountered by a rotating turbine blade.

Connell, J. R.; George, R. L.; Morris, V. R.; Sandborn, V. A.

1985-11-01

59

Mode changing stability of wind turbine in an integrated wind turbine and rechargeable battery system  

Microsoft Academic Search

Power generated by wind turbines changes due to variation in wind speed that is independent of the load power. Rechargeable batteries could be used as a reserve power source to alleviate unbalance between the load power and power generated by wind turbines. A supervisory controller is proposed for an integrated wind turbine-battery system (wind turbine electrically connected to a rechargeable

Christine A. Mecklenborg; Dushyant Palejiya; John F. Hall; Dongmei Chen

2011-01-01

60

Wind turbine noise workshop. Proceedings.  

National Technical Information Service (NTIS)

Noise generated by wind turbines is an environmental constraint on the exploitation of wind energy. It is a major consideration when seeking planning consent for the siting of machines due to the high population density in the UK and low levels of backgro...

M. Legerton

1993-01-01

61

Lightning protection for wind turbine electronics  

Microsoft Academic Search

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

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

1981-01-01

62

Wind turbine blade pitch control system  

Microsoft Academic Search

Wind turbine blade pitch control system including hydraulic actuators which pivotally drive the blades about the longitudinal axis thereof to adjust the blade pitch. The actuators are supplied with hydraulic fluid from independent sources thereof for normal blade pitch adjustment and feathering. Means are provided which, during feathering, isolate the pressurization and drain of the actuators from certain system components,

1982-01-01

63

Harmonisation of European Wind Turbine Certification.  

National Technical Information Service (NTIS)

The present situation in wind turbine certification-characterized by a co-existence of different wind turbine certification systems-o-hampers the trade of wind turbines in Europe. This situation has many negative implications on the implementation of wind...

F. J. L. Hulle C. Nath P. H. Jensen C. Eriksson P. Vionis

2001-01-01

64

Operation of a third generation wind turbine  

Microsoft Academic Search

A modern wind turbine was installed on May 26, 1982, at the USDA Conservation and Production Research Laboratory, Bushland, Texas. This wind machine was used to provide electrical energy for irrigation pumping and other agricultural loads. The wind turbine purchased for this research is an Enertech Model 44, manufactured by Enertech Corporation, Norwich, Vermont. The horizontal-axis wind turbine has a

F. C. Vosper; R. N. Clark

1983-01-01

65

AEROELASTIC STUDY OF WIND TURBINE BLADE  

Microsoft Academic Search

In the upper latitudes, wind turbines provide an effective means to generate wind power. However, owing to the fact that wind speeds are almost half in the tropical regions, wind turbines are yet to make significant penetration in tropical countries. Even 500 kW turbines tend to be large and slender. Such structures are known to be quite flexible. It is

Rajendrakumar A. Savanur; Vidyadhar Y. Mudkavi

2008-01-01

66

FAROW: A tool for fatigue and reliability of wind turbines  

Microsoft Academic Search

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

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

1993-01-01

67

Optimizing wind turbine control system parameters  

NASA Astrophysics Data System (ADS)

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, Larry L.; Vachon, William A.

1993-05-01

68

Large band simulation of the wind speed for real time wind turbine simulators  

Microsoft Academic Search

In this paper, the authors propose two modeling procedures for wind speed simulation. These procedures could be implemented on the structure of a wind turbine simulator during studies concerning stand-alone or hybrid wind systems. The evolution of a horizontal wind speed has been synthesized taking into account two components. The medium- and long-term component is described by a power spectrum

Cristian Nichita; Dragos Luca; Brayima Dakyo; Emil Ceanga

2002-01-01

69

Statistical variation of wind turbine fatigue loads.  

National Technical Information Service (NTIS)

The objective of this investigations is to quantify the statistical variation associated with fatigue loads for wind turbines. Based on aeroelastic calculations for a 1.5 MW stall regulated wind turbine, the variation is quantified, and parameters of impo...

K. Thomsen

1998-01-01

70

Vertical axis wind turbine airfoil  

SciTech Connect

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

71

Reliability analysis in wind turbine engineering  

Microsoft Academic Search

Wind turbines are being designed in accordance with deterministic design rules. As wind turbines increase in size and power, these rules may not be adequate to ascertain a safe and well balanced design. Wind turbine industry can take advantage of the safety and reliability practices in e.g. aerospace, nuclear and offshore industry. These practices include System Reliability (such as FMECA,

A. J. Seebregts; L. W. M. M. Rademakers; B. A. van den Horn

1995-01-01

72

Dynamics and Stability of Wind Turbine Generators  

Microsoft Academic Search

This paper describes the dynamic and stability properties of wind turbine generators connected to power systems. Both synchronous and induction generators are considered. A comparison is made between wind turbines, steam, and hydro units. The unusual phenomena associated with wind turbines are emphasized. The general control requirements are discussed, as well as various schemes for torsional damping such as speed

E. N. Hinrichsen; P. J. Nolan

1982-01-01

73

Wind turbine productivity considering electrical subassembly reliability  

Microsoft Academic Search

This paper proposes a reliability model for the electrical subassemblies of geared wind turbine systems with induction generators. The model is derived considering the failure of main subassemblies and their parameters are calculated. A productivity comparison is performed between the selected wind turbine systems including reliability issues.Two methods of modification for variable-speed wind turbines with Doubly Fed Induction Generators (DFIG)

H. Arabian-Hoseynabadi; H. Oraee; P. J. Tavner

2010-01-01

74

Evaluation of different turbine concepts for wind power  

Microsoft Academic Search

Every year the number of installed wind power plants in the world increases. The horizontal axis wind turbine is the most common type of turbine but there exist other types. Here, three different wind turbines are considered; the horizontal axis wind turbine and two different concepts of vertical axis wind turbines; the Darrieus turbine and the H-rotor. This paper aims

Sandra Eriksson; Hans Bernhoff; Mats Leijon

2008-01-01

75

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

76

Wind Turbine Siting: Wildlife Concerns  

NSDL National Science Digital Library

The Advanced Technology Environmental and Energy Center (ATEEC) provides this document on wildlife concerns in relation to the siting of wind turbines. The material includes individual student activities and a list of web resources intended to help teachers. Users must download this resource for viewing, which requires a free log-in. There is no cost to download the item.

Everhart, Roger; Lawton, Wendy

2012-11-21

77

Innovatory designs for ducted wind turbines  

Microsoft Academic Search

Designs for conventional ducted wind turbines usually include a large inlet for more absorption of the airflow. However, the most efficient solution should be increasing the speed of wind. In this paper, a bucket-shape ducted wind turbine is proposed and studies show that a sucking effect can be produced according to the Bernoulli's principle, and this significantly increases the wind

Ssu-Yuan Hua; Jung-Ho Cheng

2008-01-01

78

Optimum siting of wind turbine generators  

Microsoft Academic Search

This paper investigates optimum siting of wind turbine generators from the viewpoint of site and wind turbine generator selection. The methodology of analysis is based on the accurate assessment of wind power potential of various sites. The analytical computations of annual and monthly capacity factors are done using the Weibull statistical model using cubic mean cube root of wind speeds.

Suresh H. Jangamshetti; V. G. Ran

2001-01-01

79

Optimization of wind turbine vane manufacture based on queuing theory  

Microsoft Academic Search

Wind turbine vane is the key components of wind power generators effectively capture the wind. RTM is a manufacture technology of advanced composite materials, low cost, medium batch blade. Some random factors often lead to the production schedule can not be predetermined program normally. It can help reduce production costs that with the start-up costs were study of production scheduling

Qing-hui Dai; Sha Li

2011-01-01

80

Aerodynamics of Horizontal Axis Wind Turbines  

Microsoft Academic Search

\\u000a This chapter reviews the aerodynamic characteristics of horizontal axis wind turbines (HAWTs). While the aerodynamics of wind\\u000a turbine are relatively complicated in detail, the fundamental operational principle of a HAWT is that the action of the blowing\\u000a wind produces aerodynamic forces on the turbine blades to rotate them, thereby capturing the kinetic energy contained in the\\u000a wind and converting this

J. Gordon Leishman

81

Wind or fluid current turbine  

SciTech Connect

A turbine responsive to a moving fluid, which can be wind or another fluid, wherein a rotatable central shaft supports at least one radial arm with a blade assembly at the free end of the radial arm. The blade assembly includes a rocking arm pivotted on the radial arm, a blade member attached to the rocking arm, or a part thereof, and a counterweight attached to the blade. The blade assembly articulates with respect to the radial arm in response to the interaction between the moving fluid and the blade. The turbine is self starting and self controlling in response to excessive moving fluid velocity.

Sharp, P.A.

1982-06-15

82

Effect of Wind Speed on Wind Turbine Power Converter Reliability  

Microsoft Academic Search

Wind turbine power converter system (WTPCS) is a crucial device in a wind energy conversion system. This paper presents the new failure rate models and a reliability evaluation technique for the (WTPCS) considering effects of wind speeds, which can be named by the multistate probability analysis method. The case studies on the WTPCS of a 2 MW wind turbine with

Kaigui Xie; Zefu Jiang; Wenyuan Li

2012-01-01

83

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

84

A variable speed wind turbine power control  

Microsoft Academic Search

To optimize the power in a wind turbine, the speed of the turbine should be able to vary with the wind speed. A simple control scheme is proposed that will allow an induction motor to run a turbine at its maximum power coefficient. The control uses a standard V\\/Hz converter and controls the frequency to achieve the desired power at

Andrew Miller; Edward Muljadi; Donald S. Zinger

1997-01-01

85

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

86

Wind turbine reliability : a database and analysis approach.  

SciTech Connect

The US wind Industry has experienced remarkable growth since the turn of the century. At the same time, the physical size and electrical generation capabilities of wind turbines has also experienced remarkable growth. As the market continues to expand, and as wind generation continues to gain a significant share of the generation portfolio, the reliability of wind turbine technology becomes increasingly important. This report addresses how operations and maintenance costs are related to unreliability - that is the failures experienced by systems and components. Reliability tools are demonstrated, data needed to understand and catalog failure events is described, and practical wind turbine reliability models are illustrated, including preliminary results. This report also presents a continuing process of how to proceed with controlling industry requirements, needs, and expectations related to Reliability, Availability, Maintainability, and Safety. A simply stated goal of this process is to better understand and to improve the operable reliability of wind turbine installations.

Linsday, James (ARES Corporation); Briand, Daniel; Hill, Roger Ray; Stinebaugh, Jennifer A.; Benjamin, Allan S. (ARES Corporation)

2008-02-01

87

Understanding Trends in Wind Turbine Prices Over the Past Decade  

SciTech Connect

Taking a bottom-up approach, this report examines seven primary drivers of wind turbine prices in the United States, with the goal of estimating the degree to which each contributed to the doubling in turbine prices from 2002 through 2008, as well as the subsequent decline in prices through 2010 (our analysis does not extend into 2011 because several of these drivers are best gauged on a full-year basis due to seasonality issues). The first four of these drivers can be considered, at least to some degree, endogenous influences – i.e., those that are largely within the control of the wind industry – and include changes in: 1) Labor costs, which have historically risen during times of tight turbine supply; 2) Warranty provisions, which reflect technology performance and reliability, and are most often capitalized in turbine prices; 3) Turbine manufacturer profitability, which can impact turbine prices independently of costs; and 4) Turbine design, which for the purpose of this analysis is principally manifested through increased turbine size. The other three drivers analyzed in this study can be considered exogenous influences, in that they can impact wind turbine costs but fall mostly outside of the direct control of the wind industry. These exogenous drivers include changes in: 5) Raw materials prices, which affect the cost of inputs to the manufacturing process; 6) Energy prices, which impact the cost of manufacturing and transporting turbines; and 7) Foreign exchange rates, which can impact the dollar amount paid for turbines and components imported into the United States.

Bolinger, Mark; Wiser, Ryan

2011-10-26

88

Wind turbine generator  

Microsoft Academic Search

A wind-powered prime mover comprising a platform, a power shaft rotatably carried by the platform, a horizontal turn table rotatably supported atop the platform, a pair of elongate laterally spaced vertical columns projecting up from the turn table, a pair of elongate vertical rotors about and rotatably carried by the pair of columns and defining a vertically extending forwardly and

1986-01-01

89

Wind Turbine Manufacturing Process Monitoring  

SciTech Connect

To develop a practical inline inspection that could be used in combination with automated composite material placement equipment to economically manufacture high performance and reliable carbon composite wind turbine blade spar caps. The approach technical feasibility and cost benefit will be assessed to provide a solid basis for further development and implementation in the wind turbine industry. The program is focused on the following technology development: (1) Develop in-line monitoring methods, using optical metrology and ultrasound inspection, and perform a demonstration in the lab. This includes development of the approach and performing appropriate demonstration in the lab; (2) Develop methods to predict composite strength reduction due to defects; and (3) Develop process models to predict defects from leading indicators found in the uncured composites.

Waseem Faidi; Chris Nafis; Shatil Sinha; Chandra Yerramalli; Anthony Waas; Suresh Advani; John Gangloff; Pavel Simacek

2012-04-26

90

Reduced model of DFIGs wind farms using aggregation of wind turbines and equivalent wind  

Microsoft Academic Search

In this paper, a new reduced model of wind farms with doubly-fed induction generators wind turbines is proposed for representing all the wind turbines of a wind farm by one single equivalent wind turbine. The simulation results demonstrate the effectiveness of the proposed reduced model to represent the collective response of a wind farm in the point of common coupling

L. M. Fernandez; C. A. Garcia; J. R. Saenz; F. Jurado

2006-01-01

91

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

92

Frequency control and wind turbine technologies  

Microsoft Academic Search

Increasing levels of wind generation has resulted in an urgent need for the assessment of their impact on frequency control of power systems. Whereas increased system inertia is intrinsically linked to the addition of synchronous generation to power systems, due to differing electromechanical characteristics, this inherent link is not present in wind turbine generators. Regardless of wind turbine technology, the

Gillian Lalor; Alan Mullane; Mark O'Malley

2005-01-01

93

Estimating Wind Turbine–Caused Bird Mortality  

Microsoft Academic Search

Mortality estimates are needed of birds and bats killed by wind turbines because wind power generation is rapidly expanding worldwide. A mortality estimate is based on the number of fatalities assumed caused by wind turbines and found during periodic searches, plus the estimated number not found. The 2 most commonly used estimators adjust mortality estimates by rates of searcher detection

K. SHAWN SMALLWOOD

2007-01-01

94

Impedance-based structural health monitoring of wind turbine blades  

NASA Astrophysics Data System (ADS)

Wind power is a fast-growing source of non-polluting, renewable energy with vast potential. However, current wind turbine technology must be improved before the potential of wind power can be fully realized. Wind turbine blades are one of the key components in improving this technology. Blade failure is very costly because it can damage other blades, the wind turbine itself, and possibly other wind turbines. A successful damage detection system incorporated into wind turbines could extend blade life and allow for less conservative designs. A damage detection method which has shown promise on a wide variety of structures is impedance-based structural health monitoring. The technique utilizes small piezoceramic (PZT) patches attached to a structure as self-sensing actuators to both excite the structure with high-frequency excitations, and monitor any changes in structural mechanical impedance. By monitoring the electrical impedance of the PZT, assessments can be made about the integrity of the mechanical structure. Recently, advances in hardware systems with onboard computing, including actuation and sensing, computational algorithms, and wireless telemetry, have improved the accessibility of the impedance method for in-field measurements. This paper investigates the feasibility of implementing such an onboard system inside of turbine blades as an in-field method of damage detection. Viability of onboard detection is accomplished by running a series of tests to verify the capability of the method on an actual wind turbine blade section from an experimental carbon/glass/balsa composite blade developed at Sandia National Laboratories.

Pitchford, Corey; Grisso, Benjamin L.; Inman, Daniel J.

2007-05-01

95

Characterization and Impact of Low Frequency Wind Turbine Noise Emissions  

NASA Astrophysics Data System (ADS)

Wind turbine noise is a complex issue that requires due diligence to minimize any potential impact on quality of life. This study enhances existing knowledge of wind turbine noise through focused analyses of downwind sound propagation, directionality, and the low frequency component of the noise. Measurements were conducted at four wind speeds according to a design of experiments at incremental distances and angles. Wind turbine noise is shown to be highly directional, while downwind sound propagation is spherical with limited ground absorption. The noise is found to have a significant low frequency component that is largely independent of wind speed over the 20-250 Hz range. The generated low frequency noise is shown to be audible above 40 Hz at the MOE setback distance of 550 m. Infrasound levels exhibit higher dependency on wind speed, but remain below audible levels up to 15 m/s.

Finch, James

96

Wind Turbine Generator System Safety and Function Test Report for the Ventera VT10 Wind Turbine.  

National Technical Information Service (NTIS)

This report summarizes the results of a safety and function test that NREL conducted on the Ventera VT10 wind turbine. This test was conducted in accordance with the International Electrotechnical Commissions' (IEC) standard, Wind Turbine Generator System...

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

2012-01-01

97

Wind Turbine Generator System Safety and Function Test Report for the Entegrity EW50 Wind Turbine.  

National Technical Information Service (NTIS)

This report summarizes the results of a safety and function test that NREL conducted on the Entegrity EW50 wind turbine. This test was conducted in accordance with the International Electrotechnical Commissions' (IEC) standard, Wind Turbine Generator Syst...

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

2012-01-01

98

Wind turbine aerodynamics research needs assessment  

NASA Astrophysics Data System (ADS)

A prioritized list is developed for wind turbine aerodynamic research needs and opportunities which could be used by the Department of Energy program management team in detailing the DOE Five-Year Wind Turbine Research Plan. The focus of the Assessment was the basic science of aerodynamics as applied to wind turbines, including all relevant phenomena, such as turbulence, dynamic stall, three-dimensional effects, viscosity, wake geometry, and others which influence aerodynamic understanding and design. The study was restricted to wind turbines that provide electrical energy compatible with the utility grid, and included both horizontal axis wind turbines (HAWT) and vertical axis wind turbines (VAWT). Also, no economic constraints were imposed on the design concepts or recommendations since the focus of the investigation was purely scientific.

Stoddard, F. S.; Porter, B. K.

1986-01-01

99

3D MODELLING OF A WIND TURBINE USING CFD  

Microsoft Academic Search

Turbine efficiency remains a critical component of the overall economic justification for a potential wind farm. There is therefore a requirement for prediction methodologies that are capable of addressing the in-situ performance of multiple turbine installations within a specific local environment and operating in a range of conditions. The work presented here is the first stage in a programme of

David Hartwanger; Andrej Horvat

2008-01-01

100

Wind turbine testing in the NREL dynamometer test bed  

SciTech Connect

A new facility has recently been completed at the National Renewable Energy Laboratory that allows full-scale dynamometer testing of wind turbine components, from generators to complete wind turbines. This facility is equipped with a 2.5 MW motor, gearbox, and variable speed drive system to deliver shaft torque. To simulate other aspects of wind turbine loading an MTS fatigue-rated loading system is fully integrated into the facility. This will allow actuators to cyclically load the structure in a variety of ways. Enron [formally Zond] Wind Corporation has installed the first test article in the facility to help mature the Z-750 series wind turbine design. Tests include brake and control system tuning, endurance testing of gear elements and bearings, and structural testing. Some aspects of the power converter will also be tested. This paper describes the Dynamometer Test Bed and its capabilities. Also, an overview of the Zond testing program is presented.

Musial, W.; McNiff, B.

2000-06-29

101

Using generic wind turbine models to compare inertial response of wind turbine technologies  

Microsoft Academic Search

This paper describes the use of generic wind turbine models to study the comparative inertial response of wind turbine technologies, that is, their response to a frequency event on the grid such as loss of generation. The dynamic models are manufacturer-independent and portable to any dynamic modeling software. Four dominant types of wind turbine technology are modeled; the basic fixed-speed

Mohit Singh; Mithun Vyas; Surya Santoso

2010-01-01

102

Modeling Smart Structure of Wind Turbine Blade  

NASA Astrophysics Data System (ADS)

With the increasing size of wind turbine blades, the need for more sophisticated load control techniques has induced the interest for aerodynamic control systems with build-in intelligence on the blades. The paper aims to provide a way for modeling the adaptive wind turbine blades and analyze its ability for vibration suppress. It consists of the modeling of the adaptive wind turbine blades with the wire of piezoelectric material embedded in blade matrix, and smart sandwich structure of wind turbine blade. By using this model, an active vibration method which effectively suppresses the vibrations of the smart blade is designed.

Qiao, Yin-hu; Han, Jiang; Zhang, Chun-yan; Chen, Jie-ping

2012-06-01

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

Wind turbine blade tip comparison using CFD  

NASA Astrophysics Data System (ADS)

The effect of wind turbine blade tip geometry is numerically analysed using Computational Fluid Dynamics (CFD). Three different rotating blade tips are compared for attached flow conditions and the flow physics around the geometries are analysed. To this end, the pressure coefficient (Cp) is defined based on the stagnation pressure rather than on the inflow dynamic pressure. The tip geometry locally modifies the angles of attack (AOA) and the inflow dynamic pressure at each of the studied sections. However not all 3D effects could be reduced to a change of these two variables. An increase in loadings (particularly the normal force) towards the tip seem to be associated to a spanwise flow component present for the swept-back analysed tip. Integrated loads are ranked to asses wind turbine tip overall performance. It results from the comparison that a better tip shape that produced better torque to thrust ratios in both forces and moments is a geometry that has the end tip at the pitch axis. The work here presented shows that CFD may prove to be useful to complement 2D based methods on the design of new wind turbine blade tips.

Ferrer, E.; Munduate, X.

2007-07-01

105

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.

106

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

107

Wind data requirements for wind turbine generator design  

Microsoft Academic Search

The statistical methods of wind modeling for the design of tall masts, buildings, towers, and bridges are shown to be effective for the analysis of wind loads on wind turbine generators (WTG). The wind velocity profile and turbulence is defined as the instantaneous deviations from the short term mean wind speed, and is capable of reducing the fatigue life of

U. Hassan

1980-01-01

108

Dynamic Wind Loads and Vortex Structures in the Wake of a Wind Turbine  

NASA Astrophysics Data System (ADS)

We report an experimental study to characterize the dynamic wind loads and evolution of wake vortex flow structures downstream of a horizontal axis wind turbine (HAWT). The experiments were conducted in a wind tunnel with a wind turbine model placed in a boundary layer flow developed over rough and smooth surfaces in order to study the effects of roughness and the resulting velocity and turbulence fields on the wake characteristics and fatigue loads acting on the wind turbine. In addition to measuring dynamic wind loads (both aerodynamic forces and moments) acting on the wind turbine model using a six-component load cell, a high-resolution Particle Image Velocimetry (PIV) system was used to make phase-locked flow field measurements to quantify the time-evolution of the wake vortex and turbulence flow structures shedding from wind turbine blades. The detailed flow field measurements were correlated with the wind load measurements to elucidate the underlying physics associated with turbine power generation and fatigue loads acting on wind turbines.

Hu, Hui; Yang, Zifeng; Sarkar, Partha

2010-11-01

109

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

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

Heat & Flux - Enabling the Wind Turbine Controller  

Microsoft Academic Search

Heat & Flux refers to a recently invented and patented farm control concept to increase production and to reduce loads in wind farms without causing drawbacks. This is achieved by reducing the axial induction of wind turbines at the windward side of the farm. In previous works ECN proved this concept for scaled wind farms in a boundary layer wind

P. Schaak

112

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

113

Scaling wind characteristics for designing small and large wind turbines  

SciTech Connect

Since rotationally sampled wind speed spectra are required to explain the turbulence experienced by rotating wind-turbine blades, methods of estimating the shape and magnitude of the rotationally sampled wind-speed spectra for different sizes of turbines have been developed. The primary model used in this paper, called STRS-2, is an empirical one that processes turbulence measurements from a single meteorologial tower at any chosen site. The secondary model used is based upon homogeneous, isotropic turbulence theory. Several examples of direct measurement of rotationally sampled wind velocity for small turbines are used to complement the two models. Several comparisons of the estimates of turbulence experienced by different sizes of turbines indicate that all turbines will experience previously unanticipated turublence in the higher-frequency region. Further, the character and intensity of rotational sampled wind are shown to vary with the variation of turbine diameter, hub height, and rotation rate in a predictable manner.

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

1983-05-01

114

VOLTAGE QUALITY OF GRID CONNECTED WIND TURBINES  

Microsoft Academic Search

Grid connected wind turbines may cause voltage quality problems, such as voltage variation and flicker. This paper discusses the voltage variation and flicker emission of grid connected wind turbines with doubly-fed induction generators. A method to compensate flicker by using a voltage source converter (VSC) based STATCOM (Static Synchronous Compensator) is presented, which shows it is an efficient mean to

Trinh Trong Chuong

115

AN AEROACOUSTIC ANALYSIS OF WIND TURBINES  

Microsoft Academic Search

This paper describes computational aeroacoustic methods that are being applied to predict the noise radiated by wind turbines. Since the wind turbine noise problem is very challenging, only some of the important noise sources and mechanisms are being considered. These are airfoil self-noise, the effects of blade rotation, and the propagation of sound over large distances. Two aspects of airfoil

Philip J. Morris; Lyle N. Long; Kenneth S. Brentner

2004-01-01

116

OUT Success Stories: Wind Turbine Development.  

National Technical Information Service (NTIS)

Cost-shared projects with the U.S. Department of Energy and the wind industry have produced new, commercially available turbines that generate power at low costs. Advanced wind turbine technologies will be instrumental for the United States and other coun...

J. Jones B. Green

1998-01-01

117

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

118

Airfoil treatments for vertical axis wind turbines  

SciTech Connect

Sandia National Laboratories (SNL) has taken three airfoil related approaches to decreasing the cost of energy of vertical axis wind turbine (VAWT) systems; airfoil sections designed specifically for VAWTs, vortex generators (VGs), and ''pumped spoiling.'' SNL's blade element airfoil section design effort has led to three promising natural laminar flow (NLF) sections. One section is presently being run on the SNL 17-m turbine. Increases in peak efficiency and more desirable dynamic stall regulation characteristics have been observed. Vane-type VGs were fitted on one DOE/Alcoa 100 kW VAWT. With approximately 12% of span having VGs, annual energy production increased by 5%. Pumped spoiling utilizes the centrifugal pumping capabilities of hollow blades. With the addition of small perforations in the surface of the blades and valves controlled by windspeed at the ends of each blade, lift spoiling jets may be generated inducing premature stall and permitting lower capacity, lower cost drivetrain components. SNL has demonstrated this concept on its 5-m turbine and has wind tunnel tested perforation geometries on one NLF section.

Klimas, P.C.

1985-01-01

119

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

120

Streamwise development of the wind turbine boundary layer over a model wind turbine array  

NASA Astrophysics Data System (ADS)

The streamwise development of turbulence statistics and mean kinetic energy in a model wind farm consisting of 3 × 5 wind turbines is studied experimentally in a wind tunnel. The analysis uses planar Particle Image Velocimetry data obtained at the centerline plane of the wind farm, covering the inflow as well as four planes in between five downstream wind turbines. The data analysis is organized by dividing these measurement planes into three regions: the above-rotor, rotor-swept, and below-rotor regions. For each field, flow development is quantified using a properly defined relative difference norm based on an integration over each of the regions. Using this norm, it is found that the mean streamwise velocity approaches a fully developed state most rapidly, whereas the flow development is more gradual for the second-order statistics. The vertical entrainment flux of the mean kinetic energy by the Reynolds shear stress, , is observed to develop at a rate similar to that of the Reynolds shear stress rather than the mean streamwise velocity component. Its development is slowest in the layer nearest to the ground. Analysis of various terms in the mean kinetic energy equation shows that the wind turbine boundary layer has not yet reached fully developed conditions by the fifth turbine but that it is approaching such conditions. By comparing the vertical entrainment flux with the horizontal flux due to the mean flow, it is found that the former increases, whereas the latter decreases, as function of downstream distance, but that the former is already an important contributor in the developing region.

Newman, Jensen; Lebron, Jose; Meneveau, Charles; Castillo, Luciano

2013-08-01

121

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

122

Development of the Risø wind turbine airfoils  

Microsoft Academic Search

This paper presents the wind turbine airfoil development at Risø. The design method is described together with our target characteristics for wind turbine airfoils. The use of the CFD code Ellipsys2D for prediction of final target characteristics is described together with the VELUX wind tunnel testing setup. Three airfoil families were developed; Risø-A1, Risø-P and Risø-B1. The Risø-A1 airfoil family

Peter Fuglsang; Christian Bak

2004-01-01

123

Synthetic Turbulence Models for Wind Turbine Applications  

Microsoft Academic Search

Wind energy converters such as wind turbines permanently work in the atmospheric boundary layer. For the modelling of the\\u000a dynamics and for the optimisation of design and material of wind turbines synthetic models for atmospheric turbulence are\\u000a applied already for a long time. The main purpose of these models is to provide fast and efficient methods for numerical simulation\\u000a of

D. Kleinhans; R. Friedrich; A. P. Schaffarczyk; J. Peinke

2009-01-01

124

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

125

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

Microsoft Academic Search

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

A. Huskey; A. Bowen; D. Jager

2010-01-01

126

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

127

Blade pitch control of a wind turbine  

Microsoft Academic Search

A control system is described for adjusting the pitch of variable-pitch angle blades in a wind turbine generating electric power and for maintaining dynamic stability under all conditions. At low wind speeds the control system maintains the pitch of the blades at an angle close to the value providing maximum torque, and at high wind speeds the control system adjusts

Quynn

1986-01-01

128

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

129

Maximizing the wind power production of DFIG-based wind turbines at low wind speed operation  

Microsoft Academic Search

This paper introduces an improved strategy to increase the power production of wind turbines equipped with doubly fed induction generators (DFIGs) at low wind speed operation. The performance of DFIG-based wind turbines at low wind speeds, close to the cut in speed, is investigated. A modified control to extend the concept of maximum wind power tracking to cover the low

Ali H. Kasem; Ehab F. El-Saadany; H. H. El-Tamaly; Mohamed A. A. Wahab

2008-01-01

130

WindPACT Turbine Design Scaling Studies Technical Area 2: Turbine, Rotor and Blade Logistics  

SciTech Connect

Through the National Renewable Energy Laboratory (NREL), the United States Department of Energy (DOE) implemented the Wind Partnership for Advanced Component Technologies (WindPACT) program. This program will explore advanced technologies that may reduce the cost of energy (COE) from wind turbines. The initial step in the WindPACT program is a series of preliminary scaling studies intended to determine the optimum sizes for future turbines, help define sizing limits for certain critical technologies, and explore the potential for advanced technologies to contribute to reduced COE as turbine scales increase. This report documents the results of Technical Area 2-Turbine Rotor and Blade Logistics. For this report, we investigated the transportation, assembly, and crane logistics and costs associated with installation of a range of multi-megawatt-scale wind turbines. We focused on using currently available equipment, assembly techniques, and transportation system capabilities and limitations to hypothetically transport and install 50 wind turbines at a facility in south-central South Dakota.

Smith, K.

2001-07-16

131

Nonlinear control of variable speed wind turbines for power regulation  

Microsoft Academic Search

A nonlinear controller has been designed for variable speed wind turbines electric power regulation. The efficiency and reliability of wind power is shown to be depending on the applied control strategy of the wind turbine. Up to now, classical regulation is implemented only. However, under sudden wind profile variations, the wind turbine performance decrease which may cause troubles in the

Boubekeur Boukhezzar; Houria Siguerdidjane

2005-01-01

132

Dual-speed wind turbine generation  

SciTech Connect

Induction generator has been used since the early development of utility-scale wind turbine generation. An induction generator is the generator of choice because of its ruggedness and low cost. With an induction generator, the operating speed of the wind turbine is limited to a narrow range (almost constant speed). Dual- speed operation can be accomplished by using an induction generator with two different sets of winding configurations or by using a dual output drive train to drive two induction generators with two different rated speeds. With single-speed operation, the wind turbine operates at different power coefficients (Cp) as the wind speed varies. Operation at maximum Cp can occur only at a single wind speed. However, if the wind speed.varies across a wider range, the operating Cp will vary significantly. Dual-speed operation has the advantage of enabling the wind turbine to operate at near maximum Cp over a wider range of wind speeds. Thus, annual energy production can be increased. The dual-speed mode may generate less energy than a variable-speed mode; nevertheless, it offers an alternative which captures more energy than single-speed operation. In this paper, dual-speed operation of a wind turbine is investigated. Annual energy production is compared between single-speed and dual-speed operation. One type of control algorithm for dual-speed operation is proposed. Some results from a dynamic simulation will be presented to show how the control algorithm works as the wind turbine is exposed to varying wind speeds.

Muljadi, E.; Butterfield, C.P. [National Renewable Energy Lab., Golden, CO (United States); Handman, D. [Flowind Corp., San Rafael, CA (United States)

1996-10-01

133

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

134

Wind pattern recognition in neural fuzzy wind turbine control system  

Microsoft Academic Search

This paper introduces a new approach utilizing a fuzzy classifier and a modular temporal neural network to predict wind speed and direction for advanced wind turbine control systems. The fuzzy classifier estimates wind patterns and then assigns weights accordingly to each module of the temporal neural network. The finite-duration impulse response multiple-layer structure of the temporal network makes it possible

Guangdian G. Wu; Zhijie Dou

1994-01-01

135

Assessment and prediction of wind turbine noise.  

National Technical Information Service (NTIS)

The significance of basic aerodynamic noise sources for wind turbine noise are assessed, using information on the aero-acoustic mechanisms of other rotors, which have been studied in depth for many years. From the analysis, areas of potential improvement ...

M. V. Lowson

1993-01-01

136

Review of Aerodynamics for Wind Turbines  

NASA Astrophysics Data System (ADS)

This article reviews the state of the art of wind turbine rotor aerodynamics. It addresses present uncertainties in rotor design and load calculations, recent modelling efforts to reduce these uncertainties, and validation activities regarding the modelling and results thereof.

Snel, Herman

2003-07-01

137

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

138

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

139

Environmental effect of large wind turbines  

SciTech Connect

Because a wind turbine blade reflects electromagnetic radiation, it can produce ghost images and jitter on television. From simulation experiments using different strengths and time delays of the secondary signals relative to the primary signal at the receiver, a criterion has been established for interference that is unacceptable for extended periods of viewing. For a given TV transmission and given wind turbine, the interference zone can be computed by considering the propagation conditions. Small wind turbines of a few kilowatts capacity are found to produce interference with zones extending only a few tens of feet. The effect of a large wind turbine on other electromagnetic systems has been investigated, including aircraft navigational radars and Loran-C, which are relatively insensitive to interference. (LEW)

Senior, T.B.A.; Sengupta, D.L.

1981-08-01

140

Dynamically Reconfigurable Wind Turbine Blade Assembly.  

National Technical Information Service (NTIS)

A dynamically reconfigurable wind turbine blade assembly includes a plurality of reconfigurable blades mounted on a hub, an actuator fixed to each of the blades and adapted to effect the reconfiguration thereof, and an actuator power regulator for regulat...

C. H. Beauchamp S. A. Huyer S. J. Plunkett

2002-01-01

141

Fatigue of fiberglass wind turbine blade materials.  

National Technical Information Service (NTIS)

Fatigue behavior for a variety of generic materials used in wind turbine blades has been explored. Coupon testing was carried out under constant amplitude tensile fatigue loading to beyond 10(sup 7) cycles for most materials. Unidirectional materials perf...

J. F. Mandell R. M. Reed D. D. Samborsky

1992-01-01

142

Smoothing effects of distributed wind turbines. Part 1. Coherence and smoothing effects at a wind farm  

Microsoft Academic Search

Recently there has been a marked increase in wind power generation. From a power system point of view, because a wind turbine is an intermittent generator with large output fluctuation, any increase in the number of wind turbines gives rise to concerns about the adverse effects of wind turbines on power quality. The smoothing effects of wind turbine output fluctuation

Toshiya Nanahara; Masahiro Asari; Takamitsu Sato; Koji Yamaguchi; Masaaki Shibata; Tsutomu Maejima

2004-01-01

143

Modeling stochastic wind loads on vertical axis wind turbines  

NASA Astrophysics Data System (ADS)

The Vertical Axis Wind Turbine (VAWT) is a machine which extracts energy from the wind. Since random turbulence is always present, the effect of this turbulence on the wind turbine fatigue life must be evaluated. This problem is approached by numerically simulating the turbulence and calculating, in the time domain, the aerodynamic loads on the turbine blades. These loads are reduced to the form of power and cross spectral densities which can be used in standard linear structural analysis codes. The relative importance of the turbulence on blade loads is determined.

Veers, P. S.

144

Modeling stochastic wind loads on vertical axis wind turbines  

SciTech Connect

The Vertical Axis Wind Turbine (VAWT) is a machine which extracts energy from the wind. Since random turbulence is always present, the effect of this turbulence on the wind turbine fatigue life must be evaluated. This problem is approached by numerically simulating the turbulence and calculating, in the time domain, the aerodynamic loads on the turbine blades. These loads are reduced to the form of power and cross spectral densities which can be used in standard linear structural analysis codes. The relative importance of the turbulence on blade loads is determined.

Veers, P.S.

1984-01-01

145

Modeling stochastic wind loads on vertical axis wind turbines  

SciTech Connect

The Vertical Axis Wind Turbine (VAWT) is a machine which extracts energy from the wind. Since random turbulence is always present, the effect of this turbulence on the wind turbine fatigue life must be evaluated. This problem is approached by numerically simulating the turbulence and calculating, in the time domain, the aerodynamic loads on the turbine blades. These loads are reduced to the form of power and cross spectral densities which can be used in standard linear structural analysis codes. The relative importance of the turbulence on blade loads is determined.

Veers, P.S.

1984-09-01

146

SUSTAINABLE CONCRETE FOR WIND TURBINE FOUNDATIONS  

Microsoft Academic Search

The use of wind power to generate electricity continues to grow, especially given commitments by various countries throughout the world to ensure that a significant percentage of energy comes from renewable sources. In order to meet such objectives, increasingly larger turbines with higher capacity are being developed. The engineering aspects of larger turbine development tend to focus on design and

M. L. Berndt

2004-01-01

147

Wind turbine blade pitch control system  

Microsoft Academic Search

A pitch control system for a multibladed variable pitch wind turbine is described. Each of the turbine blades is pivotally driven about the longitudinal axis thereof independently of the other blades by at least a pair of hydraulic actuators. The actuators are supplied with pressurized hydraulic fluid from a first source thereof under conditions of normal pitch change adjustment. Under

P. E. Barnes; M. G. Mayo; R. Sherman

1982-01-01

148

Wave Models for Offshore Wind Turbines  

Microsoft Academic Search

In the design of wind turbines—onshore or offshore—the prediction of extreme loads as- sociated with a target (long) return period requires statistical extrapolation from available loads data. The data required for such extrapolation are obtained by stochastic time- domain simulation of the inflow turbulence and of the turbine response. Prediction of accurate loads depends on assumptions made in the simulation

Puneet Agarwal; Lance Manuely

2008-01-01

149

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

Microsoft Academic Search

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

J. Kristensen

1984-01-01

150

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

151

Control of wind turbines: Past, present, and future  

Microsoft Academic Search

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

Jason H. Laks; Lucy Y. Pao; Alan D. Wright

2009-01-01

152

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

153

Wind Turbine Generator System Acoustic Noise Test Report for the ARE 442 Wind Turbine  

Microsoft Academic Search

This test was conducted on the ARE 442 as part of the U.S. Department of Energy's (DOE's) 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 Wind Technology Center (NWTC) as a part of this

A. Huskey; J. van Dam

2010-01-01

154

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

Microsoft Academic Search

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

A. Huskey; A. Bowen; D. Jager

2010-01-01

155

Wind Turbine Safety and Function Test Report for the ARE 442 Wind Turbine  

Microsoft Academic Search

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, four turbines were tested at the National Wind Technology Center (NWTC) as a part of this project. Safety and function testing

J. van Dam; D. Baker; D. Jager

2010-01-01

156

Research and development for shrouded wind turbines  

NASA Astrophysics Data System (ADS)

A special shroud, designed for enclosing a wind turbine in order to exploit wind power as economically as possible, is presented. Several geometries, including the short diffuser shroud and the circular wing shroud, are discussed, and it is shown that a significant power augmentation can be achieved with a fairly compact shroud. Up to an 80% improvement in the shroud power augmentation has been obtained by the use of a ring-shaped flap, and proper bleeding of the shroud's external flow into its inner rear part increased its power augmentation by about 25%. The design and performance of an axial flow turbine, most suitable for the proposed shrouds, are presented, and it was shown that the turbine produces a fairly stable output for varying wind speeds while exhibiting a fairly high efficiency. The design and preliminary test results are presented of a pilot plant producing 1 hp at 5 m/s with a 3 m diameter turbine.

Igra, O.

157

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

158

The Research and Development Platform for Wind Energy System Used Induction Motor Replacing Wind Turbine  

Microsoft Academic Search

A research platform for wind energy system is developed in this paper. An inverter fed induction motor drive the wind generator replacing a real wind turbine. The power-speed characteristics of a wind turbine are physically implemented by an induction motor drive. For a given wind turbine characteristics, the shaft torque of induction motor is calculated by the given wind speed

Ming Qiao; Fei Lin; Ruixiang Hao; Xiaojie You; Trillion Q Zheng

2007-01-01

159

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.

1980-01-01

160

Subhourly wind forecasting techniques for wind turbine operations  

SciTech Connect

Three models for making automated forecasts of subhourly wind and wind power fluctuations were examined to determine the models' appropriateness, accuracy, and reliability in wind forecasting for wind turbine operation. Such automated forecasts appear to have value not only in wind turbine control and operating strategies, but also in improving individual wind turbine control and operating strategies, but also in improving individual wind turbine operating strategies (such as determining when to attempt startup). A simple persistence model, an autoregressive model, and a generalized equivalent Markhov (GEM) model were developed and tested using spring season data from the WKY television tower located near Oklahoma City, Oklahoma. The three models represent a pure measurement approach, a pure statistical method and a statistical-dynamical model, respectively. Forecasting models of wind speed means and measures of deviations about the mean were developed and tested for all three forecasting techniques for the 45-meter level and for the 10-, 30- and 60-minute time intervals. The results of this exploratory study indicate that a persistence-based approach, using onsite measurements, will probably be superior in the 10-minute time frame. The GEM model appears to have the most potential in 30-minute and longer time frames, particularly when forecasting wind speed fluctuations. However, several improvements to the GEM model are suggested. In comparison to the other models, the autoregressive model performed poorly at all time frames; but, it is recommended that this model be upgraded to an autoregressive moving average (ARMA or ARIMA) model. The primary constraint in adapting the forecasting models to the production of wind turbine cluster power output forecasts is the lack of either actual data, or suitable models, for simulating wind turbine cluster performance.

Wegley, H.L.; Kosorok, M.R.; Formica, W.J.

1984-08-01

161

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

162

Power electronics converters for wind turbine systems  

Microsoft Academic Search

The steady growth of installed wind power which reached 200 GW capacity in 2010, together with the up-scaling of the single wind turbine power capability - 7 MW's has been announced by manufacturers - has pushed the research and development of power converters towards full scale power conversion, lowered cost pr kW, and increased power density and the need for

F. Blaabjerg; M. Liserre; K. Ma

2011-01-01

163

Stability analysis of parked wind turbine blades  

Microsoft Academic Search

Wind turbine blades in parked position can experience extremely high flow angles of attack in the region of ±90 o , depending on the direction of the incoming wind. Under such conditions the flow is massively separated over the entire blade span and therefore stall induced vibrations are likely to occur with obvious implications on loads and stability. The present

E. S. Politis; P. K. Chaviaropoulos; V. A. Riziotis; S. G. Voutsinas

164

Modelling Wind Turbine Wakes in Complex Terrain  

Microsoft Academic Search

Existing engineering-type models for wakes have been developed and calibrated for flat terrain applications. However to consider the effects of the atmospheric boundary layer in a complex terrain environment, including flow separation and wind rose narrowing, requires the application of advanced methods. A method of modeling the wind turbine wakes using a Navier-Stokes solver along with the k-? turbulence model

J. M. Prospathopoulos; E. S Politis; P. K. Chaviaropoulos

165

Capacity development and profitability of wind turbines  

Microsoft Academic Search

The main objectives of the paper are to analyse and describe the driving forces behind the wind power capacity development, with Denmark as the specific case. Is it possible to establish a relation between turbine economy and the capacity expansion that could be used for regulatory purposes in reaching a specific policy-determined target for the deployment of wind power? Such

P. E. Morthorst

1999-01-01

166

Tailored airfoils for Vertical Axis Wind Turbines*  

SciTech Connect

The evolution of a family of airfoil sections designed to be used as blade elements of a vertical axis wind turbine (VAWT) is described. This evolution consists of extensive computer simulation, wind tunnel testing and field testing. The process reveals that significant reductions in system cost-ofenergy and increases in fatigue lifetime may be expected for VAWT systems using these blade elements.

Klimas, P.C.

1984-08-01

167

Tailored airfoils for vertical axis wind turbines  

SciTech Connect

The evolution of a family of airfoil sections designed to be used as blade elements of a vertical axis wind turbine (VAWT) is described. This evolution consists of extensive computer simulation, wind tunnel testing and field testing. The process reveals that significant reductions in system costs-of-energy and increases in fatigue lifetime may be expected for VAWT systems using these blade elements.

Klimas, P.C.

1984-01-01

168

Tailored airfoils for vertical axis wind turbines  

SciTech Connect

The evolution of a family of airfoil sections designed to be used as blade elements of a vertical axis wind turbine (VAWT) is described. This evolution consists of extensive computer simulation, wind tunnel testing and field testing. The process reveals that significant reductions in system costs-of-energy and increases in fatigue lifetime may be expected for VAWT systems using these blade elements.

Klimas, P.C.

1984-11-01

169

Practical aspects for small wind turbine applications  

Microsoft Academic Search

SUMMARY Low power wind turbines (WTs) are less widely applied compared to medium and high power systems. These WTs are suitable for decentralized applications and can provide electricity to residential buildings, hotels, greenhouses, etc. These WTs can be of horizontal or vertical rotor axis, must be of low cut-in wind speed and flexible in installation and operation, considering their limits

Y. Tripanagnostopoulos; A. Christodoulou; S. Tselepis; M. Souliotis; J. K. Tonui

170

Status of the 4 MW WTS-4 wind turbine  

NASA Astrophysics Data System (ADS)

The WTS-4 is a four megawatt, horizontal axis wind turbine. The specifications, characteristics and features of the WTS-4 are discussed. The major component such as rotor, nacelle and tower are described and their status in the fabrication phase is presented.

Bussolari, R. J.

171

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

Microsoft Academic Search

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

A. Huskey; A. Bowen; D. Jager

2010-01-01

172

Optimization of Wind Turbine Performance With Data-Driven Models  

Microsoft Academic Search

This paper presents a multiobjective optimization model of wind turbine performance. Three different objectives, wind power output, vibration of drive train, and vibration of tower, are used to evaluate the wind turbine performance. Neural network models are developed to capture dynamic equations modeling wind turbine performance. Due to the complexity and nonlinearity of these models, an evolutionary strategy algorithm is

Andrew Kusiak; Zijun Zhang; Mingyang Li

2010-01-01

173

Laboratory set-up for wind turbine emulation  

Microsoft Academic Search

This paper presents a laboratory set-up to be used as wind turbine emulator. The emulator can be used for research applications to drive an electrical generator in a similar way as a wind turbine, by reproducing the torque developed by a wind turbine for a given wind velocity. Also, it can be used as an educational tool to teach the

M. Chinchilla; S. Arnaltes; J. L. Rodriguez-Amenedo

2004-01-01

174

Blade number effect for a ducted wind turbine  

Microsoft Academic Search

Ducted wind turbine with multiple blades installed was believed to have a good wind power energy conversion effect. However,\\u000a little information was available on how to design a good ducted wind turbine. In this paper the effects of blade number on\\u000a a ducted wind turbine performance is studied. Numerical studies using CFD method to simulate the wind turbine performance\\u000a were

Sheng-Huan Wang; Shih-Hsiung Chen

2008-01-01

175

Optimal control of wind turbine using neural networks  

Microsoft Academic Search

Variable-speed, fixed-pitch wind turbines are required to optimize power output performance without the aerodynamic controls. In steady-state, a wind turbine generator system is operated such that the optimum points of wind rotor curve and electrical generator curve coincide. In order to obtain maximum power output of a wind turbine generator system, it is necessary to drive the wind turbine at

Mahinsasa Narayana; Ghanim Putrus

2010-01-01

176

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

177

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

178

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

179

Wind-Induced Response Analysis of Wind Turbine System  

Microsoft Academic Search

In this paper, the dynamic response of wind turbine system under wind action is numerically investigated. First, the random Fourier spectrum and rotating Fourier spectrum are proposed in this paper. These dynamic excitation models are built by starting with the point of view of random function and combining the understanding of the physical mechanism of the random excitations. Then a

GuangLing He; Jie Li

2009-01-01

180

Fatigue loading parameter identification of a wind turbine operating in complex terrain  

Microsoft Academic Search

An analytic tool is introduced for the evaluation of the fatigue loading of a wind turbine operating in complex terrain, from large scale experimental data. The fatigue loading magnitudes quantified by the equivalent load ranges of the different wind turbine components, namely blade, main shaft and tower, are modelled using multiple regression analysis in order to identify the fatigue inducing

F Mouzakis; E Morfiadakis; P Dellaportas

1999-01-01

181

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

182

A fatigue approach to wind turbine control  

NASA Astrophysics Data System (ADS)

Conventional design of wind turbine controllers is focused on speed and produced electric power. As fatigue loads is an important design consideration, the resulting design is evaluated also with respect to the fatigue loads inflicted on the turbine structure. This is normally done by performing simulations using tools like FLEX, HAWC or FAST, followed by rainflow counting in the resulting time series. This procedure constitutes an iterative design procedure involving realisations of the stress processes in order to obtain the time series needed for fatigue estimates. The focus of this paper is the elimination of the need for process realisation. To this end, known techniques for approximative fatigue load assesment based on the spectral moments of the inflicted stress histories are applied. Assuming a linearised system model, we present a novel scheme for efficient computation of these spectral moments. The scheme is applied to obtain rapid evaluation of cost functions including fatigue loads, hereby allowing efficient numerical optimisation of the controller. Three different controller design examples are given, all defined directly in terms of component life times.

Hammerum, K.; Brath, P.; Poulsen, N. K.

2007-07-01

183

Wind tunnel simulations of wind turbine wake interactions in neutral and stratified wind flow.  

NASA Astrophysics Data System (ADS)

A second programme of work is about to commence as part of a further four years of funding for the UK-EPSRC SUPERGEN-Wind large-wind-farm consortium. The first part of the initial programme at Surrey was to establish and set up appropriate techniques for both on- and off-shore boundary layers (though with an emphasis on the latter) at a suitable scale, and to build suitable rotating model wind turbines. The EnFlo wind tunnel, a UK-NCAS special facility, is capable of creating scaled neutral, stable and unstable boundary layers in its 20m long working section. The model turbines are 1/300-scale of 5MW-size, speed controlled with phase-lock measurement capability, and the blade design takes into account low Reynolds-number effects. Velocity measurements are primarily made using two-component LDA, combined with a ‘cold-wire' probe in order to measure the local turbulent heat flux. Simulation of off-shore wakes is particularly constrained because i) at wind tunnel scale the inherently low surface roughness can be below that for fully rough conditions, ii) the power required to stratify the flow varies as the square of the flow speed, and could easily be impractically large, iii) low blade Reynolds number. The boundary layer simulations, set up to give near-equilibrium conditions in terms of streamwise development, and the model turbines have been designed against these constraints, but not all constraints can be always met simultaneously in practice. Most measurements so far have been made behind just one or two turbines in neutral off- and on-shore boundary layers, at stations up to 12 disk diameters downstream. These show how, for example, the wake of a turbine affects the development of the wake of a downwind turbine that is laterally off-set by say half or one diameter, and how the unaffected part from the first turbine merges with the affected wake of the second. As expected a lower level of atmospheric turbulence causes the wakes to develop and fill-in more slowly compared with the on-shore case. A turbine can also suppress the level of atmospheric turbulence below hub height. In neutral flow, the wakes grow in width and height. However, even in mild stable stratification the vertical development of the wake deficit can be completely inhibited; at least some reduction would be expected arising from the stabilizing influence on vertical fluctuations. The width in contrast develops at about the same rate. As anticipated, the wake development is slower still in the stable case because of the lower level ambient turbulence. The maximum deficit is at a lower height than it is for neutral flow. Various aspects of the turbulence in the wake have been investigated. Second-phase work will examine a larger number of wake-turbine and wake-wake interactions, make a more detailed study of how turbines alter the atmospheric turbulence, and examine more cases of stratification. Work is also in hand related to turbines in or near forested regions, and it is expected that aspects of the physics will have links with the effect a large wind farm will have on the ABL and on the wind resource for a downwind farm. The work will produce a series of test cases to assist in the development of better wake and wind resource prediction models as well as a better understanding of wake physics.

Hancock, P. E.; Pascheke, F.

2010-09-01

184

Wind Speed Estimation Based Sensorless Output Maximization Control for a Wind Turbine Driving a DFIG  

Microsoft Academic Search

This paper proposes a wind speed estimation based sensorless maximum wind power tracking control for variable-speed wind turbine generators (WTGs). A specific design of the proposed control algorithm for a wind turbine equipped with a doubly fed induction generator (DFIG) is presented. The aerodynamic characteristics of the wind turbine are approximated by a Gaussian radial basis function network based nonlinear

Wei Qiao; Wei Zhou; JosÉ M. Aller; Ronald G. Harley

2008-01-01

185

Alternative Design Study Report: WindPACT Advanced Wind Turbine Drive Train Designs Study; November 1, 2000 -- February 28, 2002  

SciTech Connect

This report presents the Phase I results of the National Renewable Energy Laboratory's (NREL's) WindPACT (Wind Partnership for Advanced Component Technologies) Advanced Wind Turbine Drive Train Designs Study. Global Energy Concepts, LLC performed this work under a subcontract with NREL. The purpose of the WindPACT project is to identify technology improvements that will enable the cost of energy (COE) from wind turbines to be reduced. Other parts of the WindPACT project have examined blade and logistics scaling, balance-of-station costs, and rotor design. This study was designed to investigate innovative drive train designs.

Poore, R.; Lettenmaier, T.

2003-08-01

186

Investigation on wind turbine wakes: wind tunnel tests and field experiments with LIDARs  

NASA Astrophysics Data System (ADS)

An investigation on the interaction between atmospheric boundary layer flow and wind turbines is carried out with wind tunnel and LIDAR measurements. The former were carried out using hot-wire anemometry and multi-hole pressure probes in the wake of a three-bladed miniature wind turbine. The wind turbine wake is characterized by a strong velocity defect in the proximity of the rotor, and its recovery is found to depend on the characteristics of the incoming atmospheric boundary layer (mean velocity and turbulence intensity profiles). Field experiments were performed using three wind LIDARs. Bi-dimensional scans are performed in order to analyse the wake wind field with different atmospheric boundary layer conditions. Furthermore, simultaneous measurements with two or three LIDARs allow the reconstruction of multi-component velocity fields. Both LIDAR and wind tunnel measurements highlight an increased turbulence level at the wake boundary for heights comparable to the top-tip of the blades; this flow feature can produce dangerous fatigue loads on following wind turbines.

Valerio Iungo, Giacomo; Wu, Ting; Cöeffé, Juliette; Porté-Agel, Fernando

2011-11-01

187

Wind Energy Technology: Generating Power from the Wind; (USA)  

Microsoft Academic Search

Wind Energy Technology: Generating Power from the Wind (WET) announces on a biomonthly basis the current worldwide information available on wind turbine concepts and design, including the basic science of wind turbine dynamics as well as advanced components and systems research; wind turbine performance; ancillary wind turbine equipment, including system protection and interconnection devices; wind resource identification; wind turbine project

M. H. Raridon; S. C. Hicks

1991-01-01

188

TurbSim: Reliability-based wind turbine simulator  

Microsoft Academic Search

Wind turbine farms are an effective generator of electricity in windy parts of the world, with prices progressing to levels competitive with other sources. Choosing the correct turbine for a given installation requires significant engineering and the current trend leads towards groups of large horizontal axis turbines. Unfortunately, large wind turbines have to contend with large forces and other sources

Joseph T. Foley; Timothy G. Gutowski

2008-01-01

189

Wind shear climatology for large wind turbine generators  

SciTech Connect

Climatological wind shear analyses relevant to the design and operation of multimegawatt wind turbines are provided. Insight is provided for relating the wind experienced by a rotating blade in a shear flow to the analysis results. A simple analysis of the wind experienced by a rotating blade for three types of wind shear profiles under steady-state conditions is presented in graphical form. Comparisons of the magnitude and frequency of the variations in 1) the wind sensed by a single blade element, 2) the sum, and 3) the difference of the winds sensed by opposite blade elements show strong sensitivity to profile shape. These three items represent forcing functions that can be related to 1) flatwise bending moment, 2) torque on the shaft, and 3) teeter angle. A computer model was constructed to simulate rotational sampling of 10-s sampled winds from a tall tower for three different types of large wind turbines. Time series produced by the model indicated that the forcing functions on a rotating blade vary according to the shear profile encountered during each revolution as opposed to a profile derived from average wind conditions, e.g., hourly average winds. An analysis scheme was developed to establish a climatology of wind shear profiles derived from 10-s sampled winds and hourly average winds measured over a one-year period at several levels on a tall tower. Because of the sensitivity of the forcing function variability to profile shape, the analyses performed and presented are in the form of joint frequency distributions of velocity differences of the the top-to-hub versus the hub-to-bottom portion of disks of rotation for the three turbine configurations.

Elliott, D.L.; Wendell, L.L.; Heflick, S.K.

1982-10-01

190

Wind turbine on line in Hawaii  

NASA Astrophysics Data System (ADS)

The largest wind machine in the United States started generating electricity in late July in Hawaii. The Mod-5B wind-powered turbine, located on the northern tip of the island of Oahu, is rated at 3.2 megawatts and is expected to generate enough clean electricity to supply the needs of 1300 homes. The machine was developed at the National Aeronautics and Space Administration (NASA) Lewis Research Center in Cleveland, Ohio, and paid for by the Department of Energy.The turbine is based on new technology that allows its 320-ft (˜100-m) rotor to operate at variable speeds to suit changing wind conditions. It is the result of 15 years of federally sponsored research at NASA-Lewis. Conventional turbines operate at a fixed speed. After 6 months of tests, Mod-5B will be taken over and operated by the Hawaiian Electric Company, under a sales agreement with NASA. The turbine was located at the northend of Oahu primarily because of the high incidence of steady trade winds in that part of the Hawaiian chain. Renewable energy sources like the turbine are also desirable in Hawaii because of the high cost of electricity on the islands, which is principally the result of the need to import all diesel fuel and a prohibition on nuclear power plants in the state.

Maggs, William Ward

191

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

1991-12-01

192

Error analysis in wind turbine field testing  

SciTech Connect

In wind turbine field testing, one of the most important issues is understanding and accounting for data errors. Extended dynamic testing of wind turbines requires a thorough uncertainty analysis and a regimen of quality assurance steps in order to preserve accuracy. Test objectives need to be identified to determine the accuracy requirements of any data measurement, collection, and analysis process. Frequently, the uncertainty analysis reveals that the major sources of error can be allowed for with careful calibration and signal drift tracking procedures. This paper offers a basis for the discussion and development of a repeatable and accurate process to track errors and account for them in data processing.

McNiff, B [McNiff Light Industries, Carlisle, MA (United States); Simms, D [National Renewable Energy Lab., Golden, CO (United States)

1994-08-01

193

Dynamic performance analysis of a hybrid wind turbine generator system  

Microsoft Academic Search

The dynamic performances of a hybrid wind turbine generator system using a shaft generator system are investigated. The hybrid system consists of a wind turbine and generator, a rectifier, a current-source thyristor inverter, a synchronous generator driven by a prime mover and a duplex reactor. The configuration of the hybrid wind turbine generator system is explained first, and a dynamic

Yuutaro Fujii; Chihiro Hasegawa; Fujio Tatsuta; Shoji Nishikata

2008-01-01

194

Optimization Real Time Parametric Simulation of Light Wind Turbine  

Microsoft Academic Search

This article for the purpose in here is to discuss optimization of the whole light wind turbine system design and analysis of the comparison results with physical wind turbine in Yangmingshan, Taipei (460 m height Yangming Mountain) and simulate data. Using pseudo-measurement technique will be loaded and verified with the data from the real wind turbine. Other part in this

Ho-ling Fu; Jen-chieh Su

2009-01-01

195

Horizontal-Axis Research Wind Turbine at Risoe National Laboratory.  

National Technical Information Service (NTIS)

In order to obtain more accurate data for the forces on a wind turbine the Test Station for Windmills, Risoe has developed a horizontal axis test wind turbine as a standard experimental research model. The wind turbine is of a very flexible design. The ti...

J. Krogsgaard

1985-01-01

196

Wind turbine availability analysis based on statistical data  

Microsoft Academic Search

Availability is an important performance index for wind turbines. To predict wind turbine availability, failure rate and repair rate have to be known. There are some sources of wind turbine failure data that can be used to estimate parameters of the failure rate function and the repair rate. With repair rate assumed to be constant, this paper first presents maximum

Haitao Guo; Xianhui Yang; Jianping Xiang; Simon Watson

2009-01-01

197

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

198

Modeling of wind turbines for power system studies  

Microsoft Academic Search

In this paper, the modeling of wind turbines for power system studies is investigated. Complexities of various parts of a wind turbine model, such as aerodynamic conversion, drive train, and generator representation, are analyzed. The results are verified by field measurements made on a stall-regulated fixed-speed wind turbine. The modeling focuses on deriving a representation that is suitable for use

Tomas Petru; Torbjörn Thiringer

2002-01-01

199

Modeling wind turbines in power system dynamics simulations  

Microsoft Academic Search

In this panel contribution, the modeling of wind turbines in power systems dynamics simulations is discussed. First the three most important actual wind turbine concepts are described. Then, various classes of wind turbine models are introduced and it will be discussed which model type can be integrated in power system dynamics simulation software. To conclude, it will be argued that

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

2001-01-01

200

Climate change drives wind turbines  

Microsoft Academic Search

The development and prospects for wind power resources, technologies, investment, financing and banking, incentive policies, and operation and maintenance have become popular issues in wind power industry. An exhibition in May 2007 in Milan, Italy (EWEC 2007), with 229 stands on wind power technologies and techniques coinciding with the Conference, confirmed the popularity of these issues. Governments, International organisations, NGOs,

Ming Yang

2007-01-01

201

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

SciTech Connect

This report details the power quality test on the Gaia Wind 11-kW Wind Turbine as part of the U.S. Department of Energy's Independent Testing Project. In total five turbines are being tested as part of the project. Power quality testing is one of up to five test that may be performed on the turbines including power performance, safety and function, noise, and duration tests. The results of the testing provide manufacturers with reports that may be used for small wind turbine certification.

Curtis, A.; Gevorgian, V.

2011-07-01

202

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

Microsoft Academic Search

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

A. Huskey; A. Bowen; D. Jager

2010-01-01

203

The Sandia 34-meter VAWT (Vertical Axis Wind Turbine) test bed  

SciTech Connect

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) incorporating the results of recent research in VAWT aerodynamics and structural dynamics. The design and fabrication of all turbine parts has been completed, and construction of the turbine is now nearing completion, with preliminary testing underway. Turbine design and construction are reviewed and the major components of the system are summarized in this paper. 12 refs., 7 figs.

Ashwill, T.D.; Berg, D.E.; Gallo, L.R.; Grover, R.D.; Klimas, P.C.; Ralph, M.E.; Rumsey, M.A.; Stephenson, W.A.; Sutherland, H.J.

1987-10-01

204

Wind turbine mechanical characteristics and grid parameters influence on the transient voltage stability of a fixed speed wind turbine  

Microsoft Academic Search

This paper describes the effect of wind turbine mechanical characteristic of construction and grid parameters on the transient voltage stability of a fixed speed wind turbine (FSWT) connected to a simple grid. The model of FSWT has been developed in Matlab\\/Simulink. Using this model, a three-phase fault is applied close to the wind turbine (WT) and cleared by disconnecting the

L. Dusonchet; F. Massaro; E. Telaretti

2008-01-01

205

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

Microsoft Academic Search

This report details the power quality test on the Gaia Wind 11-kW Wind Turbine as part of the U.S. Department of Energy's Independent Testing Project. In total five turbines are being tested as part of the project. Power quality testing is one of up to five test that may be performed on the turbines including power performance, safety and function,

A. Curtis; V. Gevorgian

2011-01-01

206

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

SciTech Connect

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 the Research Laboratory in Bushland, Texas. Excess power will go to the Southwestern Public Service Company for the area power system.

Miller, S.

1988-05-01

207

Wind Turbine Generator System Duration Test Report for the ARE 442 Wind Turbine  

Microsoft Academic Search

This test is being 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, four turbines are being tested at the NWTC as a part of this project. Duration testing is one of up

J. van Dam; D. Baker; D. Jager

2010-01-01

208

Frequency of Upward Lightning Hits to Wind Turbines in Winter  

NASA Astrophysics Data System (ADS)

In recent years, frequent damages of wind turbines by winter lightning have been reported in the region along the Sea of Japan. It is a serious finding that lightning hits concentrate on wind turbines in this region. The authors investigated the rate of increased frequency of lightning hits on wind turbines due to its construction by using LLS (Lightning Location System) data. As a result, an experimental formula to estimate the increase rate of the frequency of lightning hits on wind turbines as a function of parameters related to the construction condition, namely the height of wind turbines, the height above the sea level and the latitude, is proposed.

Saito, Mikihisa; Ishii, Masaru; Ohnishi, Atsushi; Fujii, Fumiyuki; Matsui, Michihiro; Natsuno, Daisuke

209

Machine and Converter Reliabilities in Wind Turbines  

Microsoft Academic Search

Electrical Machine\\/Converter combinations are used in a variety of applications, from powers of Watts to MegaWatts. Some applications, such as propulsion and generation, have high reliability & availability requirements. Modern large wind turbines incorporate variable pitch blades and a variable speed Generator, which feeds the Grid through a Converter and have a need for high reliability & availability. There are

P J Tavner; G J W van Bussel; F Spinato

210

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

211

Dynamic stall model for wind turbine airfoils  

Microsoft Academic Search

A model is presented for aerodynamic lift of wind turbine profiles under dynamic stall. The model combines memory delay effects under attached flow with reduced lift due to flow separation under dynamic stall conditions. The model is based on a backbone curve in the form of the static lift as a function of the angle of attack. The static lift

J. W. Larsen; S. R. K. Nielsen; S. Krenk

2007-01-01

212

Turbulence characteristics in wind-turbine wakes  

Microsoft Academic Search

An analysis of the evolution of turbulence characteristics in wind-turbine wakes has been carried out. Based on experimental results and on numerical results obtained with a CFD code, complemented with some theoretical considerations, simple analytical expressions are proposed for the estimation of the turbulent kinetic energy, k, and its dissipation rate, ?. To obtain the turbulence spectra in the wake

A. Crespo; J. Herna´ndez

1996-01-01

213

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

214

Darrieus wind-turbine airfoil configurations  

Microsoft Academic Search

The purpose was to determine what aerodynamic performance improvement, if any, could be achieved by judiciously choosing the airfoil sections for Darrieus wind turbine blades. Ten different airfoils, having thickness to chord ratios of twelve, fifteen and eighteen percent, were investigated. Performance calculations indicated that the NACA 6-series airfoils yield peak power coefficients at least as great as the NACA.

P. G. Migliore; J. R. Fritschen

1982-01-01

215

Root region airfoil for wind turbine  

DOEpatents

A thick airfoil 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.

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

1995-01-01

216

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

217

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 ...

218

Motion responsive wind turbine tower damping  

Microsoft Academic Search

An accelerometer disposed on the support tower of a wind turbine electric generating system in the vicinity of the rotor thereof provides a signal indicative of acceleration of the tower in the direction of the rotor rotational axis. The signal is passed through a band-pass filter for summation with a torque\\/power controlled blade pitch angle reference rate signal the integral

J. M. Kos; K. I. Harner; J. P. Patrick

1983-01-01

219

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

220

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

221

Improved Diffuser for Augmenting a Wind Turbine.  

National Technical Information Service (NTIS)

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. (ERA citation 0...

K. M. Foreman B. L. Gilbert

1983-01-01

222

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

223

Hydrogen Storage in Wind Turbine Towers  

SciTech Connect

Low-cost hydrogen storage is recognized as a cornerstone of a renewables-hydrogen economy. Modern utility-scale wind turbine towers are typically conical steel structures that, in addition to supporting the rotor, could be used to store hydrogen. This study has three objectives: (1) Identify the paramount considerations associated with using a wind turbine tower for hydrogen storage; (2)Propose and analyze a cost-effective design for a hydrogen-storing tower; and (3) Compare the cost of storage in hydrogen towers to the cost of storage in conventional pressure vessels. The paramount considerations associated with a hydrogen tower are corrosion (in the form of hydrogen embrittlement) and structural failure (through bursting or fatigue life degradation). Although hydrogen embrittlement (HE) requires more research, it does not appear to prohibit the use of turbine towers for hydrogen storage. Furthermore, the structural modifications required to store hydrogen in a tower are not cost prohibitive.

Kottenstette, R.; Cotrell, J.

2003-09-01

224

Observations of wind turbine wakes and surface roughness effects on wind flow variability  

Microsoft Academic Search

Wind data collected at nine meteorological towers at the Goodnoe Hills MOD-2 wind turbine site were analyzed to characterize the wind flow over the site both in the absence and presence of wind turbine wakes. Free-flow characteristics examined were the variability of wind speed and turbulence intensity across the site as a function of wind direction and surface roughness. The

D. L. Elliott; J. C. Barnard

1990-01-01

225

Development of the Risø wind turbine airfoils  

NASA Astrophysics Data System (ADS)

This paper presents the wind turbine airfoil development at Risø. The design method is described together with our target characteristics for wind turbine airfoils. The use of the CFD code Ellipsys2D for prediction of final target characteristics is described together with the VELUX wind tunnel testing setup. Three airfoil families were developed; Risø-A1, Risø-P and Risø-B1. The Risø-A1 airfoil family was developed for rotors of 600 kW and larger. Wind tunnel testing and field testing showed that this airfoil family is well suited for stall and active stall control. However, sensitivity to roughness was higher than expected. Field tests of a 600 kW active stall wind turbine showed an estimated reduction in blade fatigue loading of up to 15% at the same annual energy yield and at the same time reduced blade weight and blade solidity. The Risø-P airfoils were developed to replace the Risø-A1 airfoils for use on pitch controlled wind turbines. Improved design objectives should reduce the sensitivity to roughness, but measurements are not yet available. The Risø-B1 airfoil family was developed for variable speed operation with pitch control of large megawatt sized rotors. Wind tunnel testing verified the high maximum lift for these airfoils, and the airfoils were found to be very insensitive to leading edge roughness. Performance with vortex generators and Gurney flaps in combination was found to be attractive for the blade root part. Field testing of a 1.5 MW rotor is in progress. Copyright

Fuglsang, Peter; Bak, Christian

2004-04-01

226

Procedures for Modeling Wind-Turbine Performance from Site Wind Data.  

National Technical Information Service (NTIS)

A key problem in wind turbine siting is predicting how a given wind turbine will perform at a given site. Solving this problem requires a model for converting wind information from a site into simulations of how a wind turbine installed at that site would...

W. T. Pennell A. H. Miller

1981-01-01

227

Fundamental time–domain wind turbine models for wind power studies  

Microsoft Academic Search

One critical task in any wind power interconnection study involves the modelling of wind turbines. This paper provides the most basic yet comprehensive time–domain wind turbine model upon which more sophisticated models along with their power and speed control mechanisms, can be developed. For this reason, this paper concentrates on the modelling of a fixed-speed wind turbine. The model includes

Surya Santoso; Ha Thu Le

2007-01-01

228

Nonlinear model identification of wind turbine with a neural network  

Microsoft Academic Search

A nonlinear model of wind turbine based on a neural network (NN) is described for the estimation of wind turbine output power. The proposed nonlinear model uses the wind speed average, the standard deviation and the past output power as input data. An anemometer with a sampling rate of one second provides the wind speed data. The NN identification process

Sousso Kélouwani; Kodjo Agbossou

2004-01-01

229

Vertical wind turbine power generating tower  

SciTech Connect

The tower comprises a base supported on a framework which mounts a wind powered turbine having a vertical axis of rotation. Air is channeled to the turbine rotor to cause counterclockwise rotation thereof by upper and lower wind deflectors. The wind deflectors include channels which cause the oncoming air to swirl in a counterclockwise motion into the rotor transmitting energy thereto. The vertical struts of the framework are also configured so as to deflect the oncoming air into the rotor in a counterclockwise direction. The rotor itself comprises columns of vertically spaced, radially extending scoops and radially extending curved blades to ensure highly efficient energy conversion. The rotor is formed with no center shaft to allow free flow of air therethrough.

Retz, P.

1982-12-28

230

Wind Energy Technology: Generating Power from the Wind  

Microsoft Academic Search

Wind Energy Technology (WET) announces on a bimonthly basis the current worldwide information available on wind turbine concepts and design, including the basic science of wind turbine dynamics as well as advanced components and systems research; wind turbine performance; ancillary wind turbine equipment, including system protection and interconnection devices; wind resource identification; wind turbine project planning and development; legal-institutional implications

B. C. Steele; G. Harman; J. Pitsenbarger

1996-01-01

231

Dynamic Models for Wind Turbines and Wind Power Plants  

SciTech Connect

The primary objective of this report was to develop universal manufacturer-independent wind turbine and wind power plant models that can be shared, used, and improved without any restrictions by project developers, manufacturers, and engineers. Manufacturer-specific models of wind turbines are favored for use in wind power interconnection studies. While they are detailed and accurate, their usages are limited to the terms of the non-disclosure agreement, thus stifling model sharing. The primary objective of the work proposed is to develop universal manufacturer-independent wind power plant models that can be shared, used, and improved without any restrictions by project developers, manufacturers, and engineers. Each of these models includes representations of general turbine aerodynamics, the mechanical drive-train, and the electrical characteristics of the generator and converter, as well as the control systems typically used. To determine how realistic model performance is, the performance of one of the models (doubly-fed induction generator model) has been validated using real-world wind power plant data. This work also documents selected applications of these models.

Singh, M.; Santoso, S.

2011-10-01

232

Dynamic behavior of variable speed wind turbines under stochastic wind  

Microsoft Academic Search

It is recognized that the most important advantage of the variable speed wind turbines (VS WTs) over the conventional constant speed (CS) machines are the improved dynamic characteristics, resulting in the reduction of the drive train mechanical stresses and output power fluctuations. In this paper alternative configurations of the electrical part of a VS WT are considered, using a squirrel

S. A. Papathanassiou; M. P. Papadopoulos

1999-01-01

233

Simple method of estimating wind turbine blade fatigue at potential wind turbine sites.  

National Technical Information Service (NTIS)

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...

J. C. Barnard L. L. Wendell

1995-01-01

234

Effect of control algorithms on fixed pitch wind turbine generators  

SciTech Connect

The effect of control upon wind turbine performance is described using actual wind speed data from a wind farm in California. The algorithms studied are currently in use by some turbine manufacturers. The algorithms were studied using a computer model of a fixed pitch, utility connected wind turbine with an induction generator. The algorithm efficiency was found to be robust over a wide range of parameters. However, the number of start/stops varied greatly with different algorithms and parameters.

Rizzi, M.P. (Measurex Corp., Cupertino, CA (USA)); Auslander, D.M. (California Univ., Berkeley, CA (USA))

1990-08-01

235

Roof mounting site analysis for micro-wind turbines  

Microsoft Academic Search

Building-integrated micro-wind turbines are promising low-cost renewable energy devices. However, the take-up of micro-wind turbines in high density suburban environments is still very limited due to issues such as: a) low wind speeds; b) high turbulence intensity; and c) the perception of potentially high levels of aerodynamic noise generated by the turbines. The wind flow field above the roof of

L. Ledo; P. B. Kosasih; P. Cooper

2011-01-01

236

The application of pulsed thermography in the inspection of wind turbine blades  

NASA Astrophysics Data System (ADS)

Wind power is a very promising source of environmentally safe, renewable, and the fast-growing energy source over the past several years. The blades of a wind turbine are considered to be an important component in wind turbine generator. Currently, bigger and more powerful wind blades are being built to increase the swept area of the turbine and extract more energy from the wind. Correspondingly, more capital cost is invested in manufacture and service. In order to reduce damage possibility and extend the wind turbine blades life, there are increasing demands for the inspection of wind turbine blades in the manufacturing factory and on site inspection. The regular inspections of wind turbine blades are done normally by using visual inspection and tapping test. To improve the safety of wind turbine blades, nondestructive testing technique using pulsed thermography is being investigated in this study. This technique utilized an active pulsed heating source that is applied on the outer surface of wind turbine blades, and an infrared camera to monitor the surface temperature distribution controlled by a computer. Reflective pulsed thermography was directly applied on several full scale wind blades, surface and subsurface defects, such as air bubbles, pin holes, edge bonding, etc. were clearly detected. Several specimens were intentionally manufactured to simulate the glue faults between supporting spars and glass fiber reinforced plastic (GFRP) shells with different thickness. Afterwards they were inspected by using pulsed thermography in laboratory. The current test results indicated that pulsed thermography has the potential for the detection of glue faults at least about 15mm thickness GFRP shell. It is shown that pulsed thermography maybe provide a powerful non-contacting technique for the inspection of wind turbine blades as well in the workshop just after the production or in the field that before and after installation of the wind blades and during reparation.

Tao, Ning; Zeng, Zhi; Feng, Lichun; Li, Xiaoli; Li, Yeshu; Zhang, Cunlin

2011-06-01

237

Site matching of wind turbine generators: a case study  

Microsoft Academic Search

Site matching of wind turbine generators is investigated based on the 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 modelled using Weibull and Rayleigh probability density functions. Wind speed data of an existing wind power station,

S. H. Jangamshetti; V. G. Rau

1999-01-01

238

Wind shear at turbine rotor heights from Doppler lidar measurements  

Microsoft Academic Search

As the capacity and size of modern wind turbines increase to take advantage of stronger winds at higher elevations, the confidence in wind resource assessment by ``extrapolation method'', routinely used in the wind energy industry, decreases. Error in wind resource approximation at elevated heights can lead to substantial uncertainty in power production and wind farm economics. Remote sensing measurements of

Y. Pichugina; R. M. Banta; N. Kelley; A. Brewer; S. Sandberg

2009-01-01

239

Predicted motion wind turbine tower damping  

SciTech Connect

Damping of the primary bending mode of a tower (12) mounting a wind turbine having a control (36) for providing a pitch blade angle reference signal (40) to modulate the pitch of the turbine blades (1) through a pitch change mechanism (38) for constant power is provided by generating the pitch blade angle reference signal as the integral (104) of the summation (266) of a torque/power controlling blade pitch angle reference rate signal (98) with an estimated acceleration signal (255) generated by filtering (250, 252, 254) the blade pitch angle reference signal (40) with the following transfer function

Harner, K. I.; Kos, J. M.; Patrick, J. P.

1984-03-06

240

Wind shear for large wind turbine generators at selected tall tower sites  

SciTech Connect

The objective of the study described in this report is to examine the nature of wind shear profiles and their variability over the height of large horizontal-axis wind turbines and to provide information on wind shear relevant to the design and opertion of large wind turbines. Wind turbine fatigue life and power quality are related through the forcing functions on the blade to the shapes of the wind shear profiles and their fluctuations over the disk of rotation.

Elliott, D.L.

1984-04-01

241

The EPRI\\/DOE Utility Wind Turbine Performance Verification Program  

Microsoft Academic Search

In 1992, the Electric Power Research Institute (EPRI) and the US Department of Energy (DOE) initiated the Utility Wind Turbine Performance Verification Program (TVP). This paper provides an overview of the TVP, its purpose and goals, and the participating utility projects. Improved technology has significantly reduced the cost of energy from wind turbines since the early 1980s. In 1992, turbines

S. Calvert; P. Goldman; E. DeMeo; C. McGowin; B. Smith; K. Tromly

1997-01-01

242

Wind Turbine Tower Optimization Method Using a Genetic Algorithm  

Microsoft Academic Search

A wind turbine tower optimization program was developed, using a genetic algorithm. This allowed a rational analysis to reduce the mass of turbine tower, by considering, for example, the distributions of diameter and wall thickness, and the positions of flanges and access ports to navigation lights. Both extreme and fatigue loads were calculated, based on wind turbine design requirements and

Shigeo Yoshida

2006-01-01

243

Causes of Bat Fatalities at Wind Turbines: Hypotheses and Predictions  

Microsoft Academic Search

Thousands of industrial-scale wind turbines are being built across the world each year to meet the growing demand for sustainable energy. Bats of certain species are dying at wind turbines in unprecedented numbers. Species of bats consistently affected by turbines tend to be those that rely on trees as roosts and most migrate long distances. Although considerable progress has been

Paul M. Cryan; Robert M. R. Barclay

2009-01-01

244

Investigation on wind power potential on Hong Kong islands—an analysis of wind power and wind turbine characteristics  

Microsoft Academic Search

This paper discusses the potential for electricity generation on Hong Kong islands through an analysis of the local weather data and typical wind turbine characteristics. An optimum wind speed, uop, is proposed to choose an optimal type of wind turbine for different weather conditions. A simulation model has been established to describe the characteristics of a particular wind turbine. A

Lin Lu; Hongxing Yang; John Burnett

2002-01-01

245

Wind ripple in vertical-axis wind turbines  

SciTech Connect

The aerodynamically induced fluctuations in the output of a VAWT have often been considered a disadvantage of such systems. The fluctuations observed in the output of a VAWT are composed of contributions due to aerodynamic effects, incident turbulence, and in some cases, mechanical resonances. In order to quantitatively assess these effects, experimental techniques have been developed which allow analysis of full-scale performance of wind turbines with particular emphasis on the effects caused by turbulence in the incident wind. These methods have been used to monitor the performance of the DOE/Sandia 17-m VAWT. Results are presented which provide an indication of the effects of incident turbulence intensity on the fluctuations in output of the turbine. Trends which relate the fluctuations in output to the fluctuations in incident wind are identified and discussed.

Akins, R.E.

1981-01-01

246

Estimating Wind Turbine Inflow Using Sparse Wind Data  

NASA Astrophysics Data System (ADS)

An accurate spatially and temporally resolved estimation of the wind inflow under various atmospheric boundary layer stability conditions is useful for several applications relevant to wind turbines. Estimations of a wind inflow plane in a neutrally stable boundary layer using sparse data (temporally resolved but spatially sparse, and spatially resolved but temporally sparse) has shown good agreement with the original data provided by a Large Eddy Simulation. A complementary Proper Orthogonal Decomposition-Linear Stochastic Estimation (POD-LSE) approach has been used for the estimation in which the POD identifies the energetic modes of the flow that are then used in estimating the time dependent flow-field using LSE. The applicability of such an approach is considered by simulating the estimation of the wind inflow using data collected in the field. Modern remote measurement approaches, such as Lidar (Light detection and ranging), can sample the wind at the multiple locations, but cannot sufficiently resolve the inflow in space in time that is required for many wind turbine applications. Since inflow estimations using the POD-LSE approach can simultaneously provide spatial and temporal behavior, the use of the approach with field data for better understanding the characteristics of the wind inflow at a particular site under different atmospheric conditions is demonstrated.

Rai, Raj; Naughton, Jonathan

2011-11-01

247

Stationary turbine component with laminated skin  

SciTech Connect

A stationary turbine engine component, such as a turbine vane, includes a internal spar and an external skin. The internal spar is made of a plurality of spar laminates, and the external skin is made of a plurality of skin laminates. The plurality of skin laminates interlockingly engage the plurality of spar laminates such that the external skin is located and held in place. This arrangement allows alternative high temperature materials to be used on turbine engine components in areas where their properties are needed without having to make the entire component out of such material. Thus, the manufacturing difficulties associated with making an entire component of such a material and the attendant high costs are avoided. The skin laminates can be made of advanced generation single crystal superalloys, intermetallics and refractory alloys.

James, Allister W. (Orlando, FL)

2012-08-14

248

Mean wind and turbulence characteristics due to induction effects near wind turbine rotors  

Microsoft Academic Search

The objective of this study was to place a model wind turbine into a wind tunnel and measure the wind characteristics in the vicinity of the spinning rotor for a variety of flow conditions. A 0.53 meter diameter model wind turbine was placed in the Meteorological Wind Tunnel facility at Colorado State University. Four different approach flow conditions were studied.

David E. Neff; Robert N. Meroney

1997-01-01

249

A continuous bivariate model for wind power density and wind turbine energy output estimations  

Microsoft Academic Search

The wind power probability density function is useful in both the design process of a wind turbine and in the evaluation process of the wind resource available at a potential site. The continuous probability models used in the scientific literature to estimate the wind power density distribution function and wind turbine energy output assume that air density is independent of

José Antonio Carta; Dunia Mentado

2007-01-01

250

Masking of wind turbine noise by wind noise  

NASA Astrophysics Data System (ADS)

Wind noise produced in tree and building measurements was measured in two areas to judge to what extent noise from wind turbines is masked by wind noise. The first place corresponds to a rural area. Buildings are low and thinly scattered. The trees are principally high hardwood. The second place is a suburb with large gardens. The vegetation consists of hedges, bushes, fruit trees, and high hardwoods. The wind speed varies in the range of 3 to 10 m/sec at a height of 7 m. It is not possible to draw conclusions about the shape of the frequency spectrum of the external wind noise in the low frequency region, below 250 Hz. For higher frequencies 1/3 octave band spectra are reliable and are almost independent of frequency; a slight decrease with frequency of 1 dB/octave can be observed in the frequency range of 250 to 4000 Hz.

Bennerhult, O.

251

Wind Turbine Reliability Database Update.  

National Technical Information Service (NTIS)

This report documents the status of the Sandia National Laboratories' Wind Plant Reliability Database. Included in this report are updates on the form and contents of the Database, which stems from a five-step process of data partnerships, data definition...

J. A. Stinebaugh P. S. Veers R. R. Hill V. A. Peters

2009-01-01

252

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

253

Pitch control of wind turbine blades in noisy and unstable wind conditions  

Microsoft Academic Search

In this paper, a new approach for control of the pitch angle of the wind turbine is represented in an unstable and noisy circumstance. Moreover, it is demonstrated that output power of the wind turbine can be efficiently controlled by the proposed control system. This method enhances (amends) the stability of the wind turbine. Besides, it improves the regulation of

Mohsen Faridi; Roghaiyeh Ansari; Seyed Ali Mousavi; Mahsa Dodman

2010-01-01

254

A robust wind turbine control using a Neural Network based wind speed estimator  

Microsoft Academic Search

Modern wind turbines are capable to work in variable speed operations. These wind turbines are provided with adjustable speed generators, like the double feed induction generator. One of the main advantage of adjustable speed generators is that they improve the system efficiency compared to fixed speed generators because turbine speed is adjusted as a function of wind speed to maximize

Oscar Barambones

2010-01-01

255

Simulation model of wind turbine 3p torque oscillations due to wind shear and tower shadow  

Microsoft Academic Search

To determine the control structures and possible power quality issues, the dynamic torque generated by the blades of a wind turbine must be represented. This paper presents an analytical formulation of the generated aerodynamic torque of a three-bladed wind turbine including the effects of wind shear and tower shadow. The comprehensive model includes turbine-specific parameters such as radius, height, and

Dale S. L. Dolan; Peter W. Lehn

2006-01-01

256

Numerical prediction of wind turbine noise  

Microsoft Academic Search

This paper develops and validates the first principle based numerical method for predicting the noise radiated from the rotating Horizontal-Axis Wind Turbine (HAWT) blades. The noise radiated to the far-field was predicted by the code based on Ffowcs Williams–Hawkings (FW–H) equation, using both original non-permeable formulation and permeable formulation. A commercially available CFD solver, ANSYS CFX 11.0, was used to

A. Tadamasa; M. Zangeneh

2011-01-01

257

Composite rotor blades for wind turbine generators  

Microsoft Academic Search

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

W. D. Weigel

1981-01-01

258

Wind Turbine Acoustics Research Bibliography with Selected Annotation.  

National Technical Information Service (NTIS)

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 St...

H. H. Hubbard K. P. Shepherd

1988-01-01

259

Investigations of a building-integrated ducted wind turbine module  

Microsoft Academic Search

So far, wind energy has not played a major role in the group of technologies for embedded generation in the built environment. However, the wind flow around conventional tall buildings generates differential pressures, which may cause an enhanced mass flow through a building-integrated turbine. As a first step, a prototype of a small-scale ducted wind turbine has been developed and

Robert K. W. Dannecker; Andrew D. Grant

2002-01-01

260

Demonstration of the Ability of RCAS to Model Wind Turbines  

Microsoft Academic Search

In recent years, the wind industry has sponsored the development, verification, and validation of comprehensive aeroelastic simulators, which are used for wind turbine design, certification, and research. Unfortunately, as wind turbines continue to grow in size and sometimes exhibit unconventional design characteristics, the existing codes do not always support the additional analysis features required for proper design. The development history,

J. Jonkman; J. Cotrell

2003-01-01

261

Using neural networks to estimate wind turbine power generation  

Microsoft Academic Search

This paper uses data collected at Central and South West Services Fort Davis wind farm (USA) to develop a neural network based prediction of power produced by each turbine. The power generated by electric wind turbines changes rapidly because of the continuous fluctuation of wind speed and direction. It is important for the power industry to have the capability to

Shuhui Li; Donald C. Wunsch; Edgar A. O'Hair; Michael G. Giesselmann

2001-01-01

262

On Pitch Control of Horizontal-Axis Large Wind Turbines  

Microsoft Academic Search

ó Most commercial large wind turbines use blade pitch action to mitigate structural loads in high wind velocity conditions. In this paper, we study the linearized dynamics of the map from blade pitch to tower top fore-aft deection in horizontal-axis wind turbines. We show that the mass and stiffness distribution of the blades at certain operating conditions determine the presence

Shashikanth Suryanarayanan; Amit Dixit

263

Stability Improvement of Wind Turbine Systems by STATCOM  

Microsoft Academic Search

The development of renewable energy based generation technologies attracts more and more attention. In particularly large number of wind turbines are being installed and connected to power system. In some countries or networks, the penetration level of wind power is significant high so as to affect the power system operation and control. Consequently, the stable operation of wind turbine systems

Z. Chen; F. Blaabjerg; Y. Hu

2006-01-01

264

Distribution of extreme gust loads of wind turbines  

Microsoft Academic Search

Extreme gust loading of wind turbines has been treated deterministically as prescribed in the design codes, without taking into account the stochastic property of the wind turbulence. In this paper a rational approach to quantify the variability of the gust loading of a wind turbine is presented and a new approach on the simulation of the extreme gusts with constrained

P. W Cheng; W. A. A. M Bierbooms

2001-01-01

265

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

266

Coordinate Control of Wind Turbine and Battery in Wind Turbine Generator System  

NASA Astrophysics Data System (ADS)

Battery is installed for with wind power generator to level the output power fluctuations, since output power fluctuations of wind power generator are large. However, if large battery is installed in wind turbine generator, the capital cost for wind power system will increase. Hence, the smallest size of battery should be preferable to save the capital cost. In this paper, we propose a methodology for controlling combined system output power and storage energy capacity of battery system. The system consists of wind turbine generator and battery energy storage system. The generated power fluctuation in low and high frequency range are smoothed by pitch angle control and battery charge or discharge. This coordinated control reduces the rated battery capacity and windmill blade stress. In our proposed method, we apply H? control theory to achieve good response and robustness. The effectiveness of the proposed control system is simulated.

Senjyu, Tomonobu; Kikunaga, Yasuaki; Tokudome, Motoki; Uehara, Akie; Yona, Atsushi; Funabashi, Toshihisa

267

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

SciTech Connect

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. For parked survival turbine components were designed to with stand 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. Construction of the turbine is in progress at this time and anticipated completion of the project is late spring of 1987.

Ashwill, T.D.

1987-01-01

268

Wind Energy Technology: Generating power from the wind: A current awareness bulletin  

Microsoft Academic Search

Wind Energy Technology: Generating Power from the Wind (WET) announces on a bimonthly basis the current worldwide information available on wind turbine concepts and design, including the basic science of wind turbine dynamics, as well as advanced components and systems research; wind turbine performance; ancillary wind turbine equipment, including system protection and interconnection devices; wind resource identification; wind turbine project

L. Smith; B. C. Steele

2008-01-01

269

Wind Energy Technology: Generating power from the wind, a current awareness bulletin  

Microsoft Academic Search

Wind Energy Technology: Generating Power from the Wind (WET) announces on a bimonthly basis the current worldwide information available on wind turbine concepts and design, including the basic science of wind turbine dynamics, as well as advanced components and systems research; wind turbine performance; ancillary wind turbine equipment, including system protection and interconnection devices; wind resource identification; wind turbine project

L. Smith; B. C. Steele

1988-01-01

270

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

271

Introduction of a new index for evaluating the effect of wind dynamics on the power of variable speed wind turbines  

Microsoft Academic Search

The instantaneous wind speed variations are ignored in the wind turbine power curves. Hence, the output power of the wind turbines becomes a function of only the average wind speed. In the variable-speed wind turbines, the output power is a function of wind speed as well as the wind dynamics because in order to extract the maximum amount of electrical

M. H. Zamani; G. H. Riahy; R. Z. Foroushani

2008-01-01

272

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

273

Wind turbine generator trends for site-specific tailoring  

NASA Astrophysics Data System (ADS)

Turbine optimization for specific wind regimes and climate conditions is becoming more common as the market expands into new territories (offshore, low-wind regimes) and as technology matures. Tailoring turbines for specific sites by varying rotor diameter, tower height and power electronics may be a viable technique to make wind energy more economic and less intermittent. By better understanding the wind resource trends and evaluating important wind turbine performance parameters such as specific power (ratio of rated power and rotor swept area), developers and operators can optimize plant output and better anticipate operational impacts. This article presents a methodology to evaluate site-specific wind data for turbine tailoring. Wind characteristics for the Tehachapi wind resource area in California were utilized for this study. These data were used to evaluate the performance of a range of wind turbine configurations. The goal was to analyse the variations in wind power output for the area, assess the changes in these levels with the time of day and season and determine how turbine configuration affects the output. Wind turbine output was compared with California statewide system electrical demand to evaluate the correlation of the wind resource site with local peak demand loads. A comparison of the commercial value of electricity and corresponding wind generation is also presented using a time-dependent valuation methodology. Copyright

Jackson, K.; van Dam, C. P.; Yen-Nakafuji, D.

2005-10-01

274

Wind turbine and method for power generation  

SciTech Connect

A wind turbine for generation of electricity is described comprising a large, lightweight wheel attached to a fixed vertical central pylon and oriented to rotate in a vertical plane around a boom having an axis that is substantially horizontal, and pivoted at one end to the pylon. The wind wheel is supported at its rim by a carriage assembly that is constrained to move in a circular horizontal path about the central pylon. The wheel has a cylindrical outer rim and may include one or more perimeter frame structures. The outer surface of the rim is essentially flat in cross section and presents a traction surface for the takeoff of energy from the rim of the wheel. The wheel has a plurality of uniformly spaced radial spindles on which are rolled sails (Soft airfoils), which when unfurled catch the wind to provide the rotational motion to the wheel. The carriage assembly may be moved around the pylon by driver means to accommodate for changes in wind direction, or the wind wheel as a whole can be allowed to move freely to assume the preferred wind direction in the manner of a weather vane. The wheel and frame structure are secured to and supports the horizontal boom which lies colinear with the axis of the wheel and projects longitudinally in both directions from the central plane of the wheel. The entire boom structure is supported by means of stays from the perimeter of the rim to the ends of the boom. Detailed rigging and traveler assemblies for control and operation of the wind turbine are disclosed.

Cook, G.E.

1982-09-21

275

Dynamic modeling of doubly fed induction generator wind turbines  

Microsoft Academic Search

It is now recognized that many large wind farms will employ doubly fed induction generator (DFIG) variable speed wind turbines. A number of such wind farms are already in operation and more are planned or under construction. With the rising penetration of wind power into electricity networks, increasingly comprehensive studies are required to identify the interaction between the wind farm(s)

Janaka B. Ekanayake; Lee Holdsworth; XueGuang Wu; Nicholas Jenkins

2003-01-01

276

Investigating Interactions Between Wind Turbines and the Atmosphere  

NASA Astrophysics Data System (ADS)

With wind energy gaining in popularity and wind farms being developed faster than ever, it is important to quantify any effect these farms have on the atmosphere. Knowing these effects will assist in site selection as well as in optimizing array efficiency. Previous studies have looked at atmosphere-wind farm interaction using models at coarse resolutions. This study goes down to resolutions as fine as 15 m in order to resolve the turbine blades themselves. A simple wind turbine model based on the Blade Element Momentum method is used to determine the forces exerted by the turbine blades onto the incoming air flow. The turbine model results are validated against three different wind turbines - the NREL/NASA Ames UAE turbine, an LM Glasfiber turbine, and a Tjaereborg turbine. Once validated, parameters from the model are used to estimate the wind velocity in the wake of a turbine. The energy lost in a single wake is extrapolated to get a rough estimate of how much energy is lost from the atmosphere from large wind farms. The next step will be to apply the forces from the turbine model into a 3D atmospheric model which will couple the blade forces into the atmospheric flow field. The coupled model will be used to examine turbine wake development and how this feeds back into atmospheric processes.

Sta Maria, M. V.; Jacobson, M. Z.

2008-12-01

277

State of the art in wind turbine aerodynamics and aeroelasticity  

NASA Astrophysics Data System (ADS)

A comprehensive review of wind turbine aeroelasticity is given. The aerodynamic part starts with the simple aerodynamic Blade Element Momentum Method and ends with giving a review of the work done applying CFD on wind turbine rotors. In between is explained some methods of intermediate complexity such as vortex and panel methods. Also the different approaches to structural modelling of wind turbines are addressed. Finally, the coupling between the aerodynamic and structural modelling is shown in terms of possible instabilities and some examples.

Hansen, M. O. L.; Sørensen, J. N.; Voutsinas, S.; Sørensen, N.; Madsen, H. Aa.

2006-06-01

278

Study on power control of doubly fed wind turbine  

Microsoft Academic Search

This paper firstly introduces the system model of wind turbine. According to the input mechanical energy and the power curve of wind turbine, we study the Steady-state Characteristics, relationship of the power and turque. Then the power output characteristic of the wind turbine is simulated by MATLAB.The simulation result shows that the Double-Fed Induction Generator(DFIG) system can realize optimal power

Xingjia Yao; Jun Liu; Zuoxia Xing; Yanjun Jing; Guangbo Li

2008-01-01

279

Wind Turbine Generator System Safety and Function Test Report for the Southwest Windpower H40 Wind Turbine  

Microsoft Academic Search

The objective of this test was to evaluate the safety and function characteristics of the Whisper H40 wind turbine. The general requirements of wind turbine safety and function tests are defined in the IEC standard WT01. The testing was conducted in accordance with the National Wind Technology Center (NWTC) Quality Assurance System, including the NWTC Certification Team Certification Quality Manual

J. van Dam; H. Link; M. Meadors; J. Bianchi

2002-01-01

280

An introduction to the small wind turbine project  

SciTech Connect

Small wind turbines are typically used for the remote or rural areas of the world including: a village in Chile; a cabin dweller in the U.S.; a farmer who wants to water his crop; or a utility company that wants to use distributed generation to help defer building new transmission lines and distribution facilities. Small wind turbines can be used for powering communities, businesses, homes, and miscellaneous equipment to support unattended operation. This paper covers the U.S. Department of Energy/National Renewable Energy Laboratory Small Wind Turbine project, its specifications, its applications, the subcontractors and their small wind turbines concepts. 4 refs., 4 figs.

Forsyth, T.L.

1997-07-01

281

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

282

Probabilistic characterization of wind turbine blades via aeroelasticity and spinning finite element formulation  

NASA Astrophysics Data System (ADS)

Wind energy is an increasingly important component of this nation's renewable energy portfolio, however safe and economical wind turbine operation is a critical need to ensure continued adoption. Safe operation of wind turbine structures requires not only information regarding their condition, but their operational environment. Given the difficulty inherent in SHM processes for wind turbines (damage detection, location, and characterization), some uncertainty in conditional assessment is expected. Furthermore, given the stochastic nature of the loading on turbine structures, a probabilistic framework is appropriate to characterize their risk of failure at a given time. Such information will be invaluable to turbine controllers, allowing them to operate the structures within acceptable risk profiles. This study explores the characterization of the turbine loading and response envelopes for critical failure modes of the turbine blade structures. A framework is presented to develop an analytical estimation of the loading environment (including loading effects) based on the dynamic behavior of the blades. This is influenced by behaviors including along and across-wind aero-elastic effects, wind shear gradient, tower shadow effects, and centrifugal stiffening effects. The proposed solution includes methods that are based on modal decomposition of the blades and require frequent updates to the estimated modal properties to account for the time-varying nature of the turbine and its environment. The estimated demand statistics are compared to a code-based resistance curve to determine a probabilistic estimate of the risk of blade failure given the loading environment.

Velazquez, Antonio; Swartz, R. Andrew

2012-03-01

283

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

Federal Register 2010, 2011, 2012, 2013

...Power Systems Americas, Inc. (Wind Turbine Nacelles and Generating Sets) Fort Smith...special-purpose subzone at the wind turbine nacelle and generating set manufacturing...activity related to the manufacturing of wind turbine nacelles and generating sets at the...

2012-06-01

284

76 FR 54481 - Wind Turbine Guidelines Advisory Committee; Announcement of Public Meeting and Webcast  

Federal Register 2010, 2011, 2012, 2013

...94300-1122-0000-Z2] RIN 1018-AX45 Wind Turbine Guidelines Advisory Committee; Announcement...Service (Service), will host a Wind Turbine Guidelines Advisory Committee (Committee...Alternate Designated Federal Officer, Wind Turbine Guidelines Advisory Committee. [FR...

2011-09-01

285

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

286

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

287

Wind tunnel investigation of the wake structure within small wind turbine farms.  

National Technical Information Service (NTIS)

The primary aim of the work reported here was to obtain comprehensive data on the mean and turbulent flow within wind farms of horizontal axis wind turbines. Wakes within wind farms of 15 wind turbine models have been investigated in some detail in the la...

U. Hassan

1993-01-01

288

Rotationally Sampled Wind and MOD-2 Wind Turbine Response. Final Report.  

National Technical Information Service (NTIS)

In an effort to learn more about how wind behaves hear wind turbines, researchers rotationally sampled winds by attaching sensors to the blades of a MOD-2 wind turbine. This fieldwork demonstrates the feasibility of a blade-mounted measuring technique and...

J. R. Connell R. L. George V. R. Morris V. A. Sandborn

1985-01-01

289

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

290

Abrasive flow machining of turbine engine components  

Microsoft Academic Search

A technique used for improving the performance and durability of aircraft turbine engines by flowing abrasive media through critical components is described. The process is abrasive only where the flow is restricted: the extrusion area (the process is also known as extrusion honing). Process parameters including extrusion pressure and the volume of flow are presented, and the tooling and media

Rhoades

1990-01-01

291

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

292

A shape adaptive airfoil for a wind turbine blade  

NASA Astrophysics Data System (ADS)

The loads on wind turbine components are primarily from the blades. It is important to control these blade loads in order to avoid damaging the wind turbine. Rotor control technology is currently limited to controlling the rotor speed and the pitch of the blades. As blades increase in length it becomes less desirable to pitch the entire blade as a single rigid body, but instead there is a requirement to control loads more precisely along the length of the blade. This can be achieved with aerodynamic control devices such as flaps. Morphing technologies are good candidates for wind turbine flaps because they have the potential to create structures that have the conflicting abilities of being load carrying, light-weight and shape adaptive. A morphing flap design with a highly anisotropic cellular structure is presented which is able to undergo large deflections and high strains without a large actuation penalty. An aeroelastic analysis couples the work done by aerodynamic loads on the flap, the flap strain energy and the required actuation work to change shape. The morphing flap is experimentally validated with a manufactured demonstrator and shown to have reduced actuation requirements compared to a conventional hinged flap.

Daynes, Stephen; Weaver, Paul M.

2011-03-01

293

Wind Turbine Reliability: A Database and Analysis Approach.  

National Technical Information Service (NTIS)

The US wind Industry has experienced remarkable growth since the turn of the century. At the same time, the physical size and electrical generation capabilities of wind turbines has also experienced remarkable growth. As the market continues to expand, an...

A. S. Benjamin D. Briand J. Linsday J. A. Stinebaugh R. R. Hill

2008-01-01

294

Certification for Small Wind Turbine Installers: What's the Hang Up.  

National Technical Information Service (NTIS)

Several programs have been implemented to support the advancement of a professional, mature small wind industry and to ensure that this industry moves forward in a sustainable direction. The development of a standard for small wind turbine systems and the...

F. Oteri K. Sinclair

2012-01-01

295

Data Analysis Method for Wind Turbine Dynamic Response Testing.  

National Technical Information Service (NTIS)

The Wind Research Branch at the Solar Energy Research Institute (SERI) has developed an efficient data analysis package for personal computer use in response to growing needs of the wind turbine industry and SERI's Cooperative Field Test Program. This new...

T. L. Olsen S. M. Hock

1989-01-01

296

Comparison and analysis of non-destructive testing techniques suitable for delamination inspection in wind turbine blades  

Microsoft Academic Search

Wind turbine blades are one of the key components of a complete wind turbine system due to their significant effect in the overall performance of the system. They are fabricated with composite materials with polymeric matrices and the current manufacturing processes are still highly manual resulting in different types of defects. Thus, non-destructive testing (NDT) techniques that provide surface and

I. Amenabar; A. Mendikute; A. López-Arraiza; M. Lizaranzu; J. Aurrekoetxea

2011-01-01

297

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

298

Wind Turbine Safety and Function Test Report for the ARE 442 Wind Turbine.  

National Technical Information Service (NTIS)

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, ...

D. Baker D. Jager J. V. Dam

2010-01-01

299

Dynamic simulation of dual-speed wind turbine generation  

SciTech Connect

Induction generators have been used since the early development of utility-scale wind turbine generation. An induction generator is the generator of choice because of its ruggedness, and low cost. With an induction generator, the operating speed of the wind turbine is limited to a narrow range (almost constant speed). Dual- speed operation can be accomplished by using an induction generator with two different sets of winding configurations or by using two induction generators with two different rated speeds. With single- speed operation, the wind turbine operates at different power coefficients (Cp) as the wind speed varies. The operation at maximum Cp can occur only at a single wind speed. However, if the wind speed varies across a wider range, the operating Cp will vary significantly. Dual-speed operation has the advantage of enabling the wind turbine to operate at near maximum Cp over a wider range of wind-speeds. Thus, annual energy production can be increased. The dual-speed mode may generate less energy than a variable-speed mode; nevertheless, it offers an alternative to capture more energy than single-speed operation. In this paper, dual-speed operation of a wind turbine will be investigated. One type of control algorithm for dual- speed operation is proposed. Results from a dynamic simulation will be presented to show how the control algorithm works and how power, current and torque of the system vary as the wind turbine is exposed to varying wind speeds.

Muljadi, E.; Butterfield, C.P.

1996-10-01

300

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

Microsoft Academic Search

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

J. M. Jonkman; P. D. Sclavounos

2006-01-01

301

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

302

Tip loss corrections for wind turbine computations  

NASA Astrophysics Data System (ADS)

As an essential ingredient in the blade element momentum theory, the tip loss effect of rotors plays an important role in the prediction of wind turbine performance. Various tip loss corrections based on the Prandtl tip loss function are analysed in the article. Comparisons with measurements and theoretical analyses show that existing tip loss correction models are inconsistent and fail to predict correctly the physical behaviour in the proximity of the tip. A new tip loss correction model is proposed that remedies the inconsistency. Comparisons between numerical and experimental data show that the new model results in much better predictions of the loading in the tip region. Copyright

Shen, Wen Zhong; Mikkelsen, Robert; Nørkær Sørensen, Jens; Bak, Christian

2005-10-01

303

Effects of Capacitor Bank on Fault Ride Through Capability of Induction Generator Based Wind Turbines  

Microsoft Academic Search

Wind turbine installation is increasing rapidly. In some networks, wind power penetration is significantly high and the performance of wind turbine plays an important role in power system operation and control. Especially, the behavior of wind turbines during a power system disturbance would affect power system stability and supply security. Some existing wind turbines are still based on fixed speed

Y. Hu; Z. Chen

2010-01-01

304

The statistical smoothing of power delivered to utilities by multiple wind turbines  

Microsoft Academic Search

A relationship for estimating the spectrum of the power delivered from multiple wind turbines from the spectrum of the power delivered by a single wind turbine is derived. It is assumed in the derivation that the wind power time series of each wind turbine is stationary and can be related to time series or neighboring wind turbines by a spatial

G. McNerney; R. Richardson

1992-01-01

305

Fully Coupled Dynamic Analysis of a Floating Wind Turbine System.  

National Technical Information Service (NTIS)

The use of wind power is in a period of rapid growth worldwide and wind energy systems have emerged as a promising technology for utilizing offshore wind resources for the large scale generation of electricity Drawing upon the maturity of wind turbine and...

J. E. Withee

2004-01-01

306

Testing Small Wind Turbines at NREL's NWTC (Presentation)  

Microsoft Academic Search

Reducing barriers to wind energy expansion, stabilizing the market, and expanding the number of small wind turbine (SWT) systems installed in the United States are important goals for the Department of Energy's (DOE) Wind and Hydropower Technologies Program. One of the barriers for the distributed wind market is the lack of SWT systems that are independently tested and certified. The

Sinclair

2008-01-01

307

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

308

Aeroelastic Instabilities of Large Offshore and Onshore Wind Turbines  

Microsoft Academic Search

Offshore turbines are gaining attention as means to capture the immense and relatively calm wind resources available over deep waters. This paper examines the aeroelastic stability of a three-bladed 5MW conceptual wind turbine mounted atop a floating barge with catenary moorings. The barge platform was chosen from the possible floating platform concepts, because it is simple in design and easy

Gunjit Bir; Jason Jonkman

2007-01-01

309

Wind turbine modeling, LVRT field test and certification  

Microsoft Academic Search

The need to validate wind turbine models for the use in grid integration studies is addressed in an increasing number of grid codes. In several countries (Spain, Australia, UK, Germany) requirements for simulation models are now required for the grid access of wind turbines. In Germany, triggered by the new renewable energy law (EEG), a guideline for validating electrical simulation

Jens Fortmann; Lijun Cai; Stephan Engelhardt; Jorg Kretschmann

2011-01-01

310

State of the art in wind turbine aerodynamics and aeroelasticity  

Microsoft Academic Search

A comprehensive review of wind turbine aeroelasticity is given. The aerodynamic part starts with the simple aerodynamic Blade Element Momentum Method and ends with giving a review of the work done applying CFD on wind turbine rotors. In between is explained some methods of intermediate complexity such as vortex and panel methods. Also the different approaches to structural modelling of

M. O. L. Hansen; J. N. Sørensen; S. Voutsinas; N. Sørensen; H. Aa. Madsen

2006-01-01

311

Active and Passive Lift Force Augmentation Techniques on Wind Turbines  

Microsoft Academic Search

The paper presents a short review of active and passive lift force augmentation concepts for wind turbines. The few models presented were analyzed using CFD to determine their potential in terms of improved performance of wind turbines. There will also be presented and computational aspects related to modeling active and passive control systems. Numerical simulations are based on RANS (Reynolds

F. Frunzulica; H. Dumitrescu; R. Mahu; O. Preotu

2011-01-01

312

How I Home-Built an Electricity Producing Wind Turbine  

NSDL National Science Digital Library

This site has step-by-step instructions on how to build a wind turbine with parts you can purchase from the hardware store and e-bay. The website includes photographs and text which illustrate how to build the wind turbine.

Davis, Michael

2010-10-20

313

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

314

Representing wind turbine electrical generating systems in fundamental frequency simulations  

Microsoft Academic Search

Increasing numbers of wind turbines are being erected. In the near future, they may start to influence the dynamics of electrical power systems by interacting with conventional generation equipment and with loads. The impact of wind turbines on the dynamics of electrical power systems therefore becomes an important subject, studied by means of power system dynamics simulations. Various types of

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

2003-01-01

315

Wind turbines---low level noise sources interfering with restoration?  

Microsoft Academic Search

Wind turbines generate a low level noise and would thus not be expected to cause annoyance and disturb rest. In a society where people are being exposed to an increasing noise load, moderate and low level noise sources may also be perceived as annoying and hence inhibit restoration. This article presents an analysis of two socio-acoustic studies of wind turbine

Eja Pedersen; Kerstin Persson Waye

2008-01-01

316

Terrain induced loads on pitch regulated wind turbines.  

National Technical Information Service (NTIS)

This paper discusses the loads for pitch-regulated wind turbines in different types of terrain. Its objective is to identify the important load-generating mechanisms in complex terrain in order to be able to predict the loads for wind turbines erected in ...

K. Thomsen S. Markkilde Petersen J. Thirstrup Petersen S. Oeye M. Friedrich

1996-01-01

317

Failure Modes and Effects Analysis (FMEA) for wind turbines  

Microsoft Academic Search

The Failure Modes and Effects Analysis (FMEA) method has been used to study the reliability of many different power generation systems. This paper now applies that method to a wind turbine (WT) system using a proprietary software reliability analysis tool. Comparison is made between the quantitative results of an FMEA and reliability field data from real wind turbine systems and

H. Arabian-Hoseynabadi; H. Oraee; P. J. Tavner

2010-01-01

318

Application of Damage Detection Techniques Using Wind Turbine Modal Data.  

National Technical Information Service (NTIS)

As any structure ages, its structural characteristics will also change. The goal of this work was to determine if modal response data fkom a wind turbine could be used in the detection of damage. The input stimuli to the wind turbine were from traditional...

E. Gross M. Rumsey T. Simmermacher R. I. Zadoks

1998-01-01

319

Wind turbine test Nordtank NTK 500/37. System test.  

National Technical Information Service (NTIS)

The report describes measurements carried out on the Nordtank NTK 500/37 wind turbine during the period from September 1992 to September 1993. The measurements were carried out at Risoe located near Roskilde Fjord. The test site, the wind turbine, the dat...

S. Markkilde Petersen

1994-01-01

320

Coupled Dynamic Modeling of Floating Wind Turbine Systems: Preprint  

Microsoft Academic Search

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

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

2006-01-01

321

Maximum Power Point Tracking of a Microprocessor - Controlled Wind Turbine.  

National Technical Information Service (NTIS)

A wind turbine adaptative control has been designed and optimized. The horizontal axis wind turbine and its mechanical regulation device is first described. An impedance matching is shown to be necessary and is obtained with a direct-direct static convert...

C. Kraif

1984-01-01

322

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

323

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

324

(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

325

Wind turbine generator with improved operating subassemblies  

SciTech Connect

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., M. C.

1985-10-08

326

Spatial mapping and attribution of Wyoming wind turbines  

USGS Publications Warehouse

This Wyoming wind-turbine data set represents locations of wind turbines found within Wyoming as of August 1, 2009. Each wind turbine is assigned to a wind farm. For each turbine, this report contains information about the following: potential megawatt output, rotor diameter, hub height, rotor height, land ownership, county, wind farm power capacity, the number of units currently associated with its wind farm, the wind turbine manufacturer and model, the wind farm developer, the owner of the wind farm, the current purchaser of power from the wind farm, the year the wind farm went online, and the status of its operation. Some attributes are estimates based on information that was obtained through the American Wind Energy Association and miscellaneous online reports. The locations are derived from August 2009 true-color aerial photographs made by the National Agriculture Imagery Program; the photographs have a positional accuracy of approximately ?5 meters. The location of wind turbines under construction during the development of this data set will likely be less accurate than the location of turbines already completed. The original purpose for developing the data presented here was to evaluate the effect of wind energy development on seasonal habitat used by greater sage-grouse. Additionally, these data will provide a planning tool for the Wyoming Landscape Conservation Initiative Science Team and for other wildlife- and habitat-related projects underway at the U.S. Geological Survey's Fort Collins Science Center. Specifically, these data will be used to quantify disturbance of the landscape related to wind energy as well as quantifying indirect disturbances to flora and fauna. This data set was developed for the 2010 project 'Seasonal predictive habitat models for greater sage-grouse in Wyoming.' This project's spatially explicit seasonal distribution models of sage-grouse in Wyoming will provide resource managers with tools for conservation planning. These specific data are being used for assessing the effect of disturbance resulting from wind energy development within Wyoming on sage-grouse populations.

O'Donnell, Michael S.; Fancher, Tammy S.

2010-01-01

327

Design of a miniature wind turbine for powering wireless sensors  

NASA Astrophysics Data System (ADS)

In this paper, a miniature wind turbine (MWT) system composed of commercially available off-the-shelf components was designed and tested for harvesting energy from ambient airflow to power wireless sensors. To make MWT operate at very low air flow rates, a 7.6 cm thorgren plastic Propeller blade was adopted as the wind turbine blade. A sub watt brushless DC motor was used as generator. To predict the performance of the MWT, an equivalent circuit model was employed for analyzing the output power and the net efficiency of the MWT system. In theory, the maximum net efficiency 14.8% of the MWT system was predicted. Experimental output power of the MWT versus resistive loads ranging from 5 ohms to 500 ohms under wind speeds from 3 m/s to 4.5 m/s correlates well with those from the predicted model, which means that the equivalent circuit model provides a guideline for optimizing the performance of the MWT and can be used for fulfilling the design requirements by selecting specific components for powering wireless sensors.

Xu, F. J.; Yuan, F. G.; Hu, J. Z.; Qiu, Y. P.

2010-03-01

328

Input Turbulence Features at a Megawatt-Size Wind Turbine, Medicine Bow, Wyoming.  

National Technical Information Service (NTIS)

In response to recent observations that wind turbulence has a strong effect on wind turbine fatigue life, measurements of turbulent wind velocity profiles have been made at the Medicine Bow, Wyoming, WTS-4 wind turbine site. These measurements were taken ...

J. R. Connell V. R. Morris M. E. Hinchee

1986-01-01

329

Locations and attributes of wind turbines in Colorado, 2011  

USGS Publications Warehouse

This dataset represents an update to U.S. Geological Survey Data Series 597. Locations and attributes of wind turbines in Colorado, 2009 (available at http://pubs.usgs.gov/ds/597/). This updated Colorado wind turbine Data Series provides geospatial data for all 1,204 wind turbines established within the State of Colorado as of September 2011, an increase of 297 wind turbines from 2009. Attributes specific to each turbine include: turbine location, manufacturer and model, rotor diameter, hub height, rotor height, potential megawatt output, land ownership, county, and development status of the wind turbine. Wind energy facility data for each turbine include: facility name, facility power capacity, number of turbines associated with each facility to date, facility developer, facility ownership, and year the facility went online. The locations of turbines are derived from 1-meter true-color aerial photographs produced by the National Agriculture Imagery Program (NAIP); the photographs have a positional accuracy of about ±5 meters. Locations of turbines constructed during or prior to August 2009 are based on August 2009 NAIP imagery and turbine locations constructed after August 2009 were based on September 2011 NAIP imagery. The location of turbines under construction during September 2011 likely will be less accurate than the location of existing turbines. This data series contributes to an Online Interactive Energy Atlas developed by the U.S. Geological Survey (http://my.usgs.gov/eerma/). The Energy Atlas synthesizes data on existing and potential energy development in Colorado and New Mexico and includes additional natural resource data layers. This information may be used by decisionmakers to evaluate and compare the potential benefits and tradeoffs associated with different energy development strategies or scenarios. Interactive maps, downloadable data layers, comprehensive metadata, and decision-support tools also are included in the Energy Atlas. The format of the Energy Atlas is designed to facilitate the integration of information about energy with key terrestrial and aquatic resources for evaluating resource values and minimizing risks from energy development.

Carr, Natasha B.; Diffendorfer, James E.; Fancher, Tammy; Hawkins, Sarah J.; Latysh, Natalie; Leib, Kenneth J.; Matherne, Anne Marie

2013-01-01

330

Locations and attributes of wind turbines in New Mexico, 2011  

USGS Publications Warehouse

This dataset represents an update to U.S. Geological Survey Data Series 596. Locations and attributes of wind turbines in New Mexico, 2009 (available at http://pubs.usgs.gov/ds/596/).This updated New Mexico wind turbine Data Series provides geospatial data for all 562 wind turbines established within the State of New Mexico as of June 2011, an increase of 155 wind turbines from 2009. Attributes specific to each turbine include: turbine location, manufacturer and model, rotor diameter, hub height, rotor height, potential megawatt output, land ownership, county, and development status of wind turbine. Wind energy facility data for each turbine include: facility name, facility power capacity, number of turbines associated with each facility to date, facility developer, facility ownership, and year the facility went online. The locations of turbines are derived from 1-meter true-color aerial photographs produced by the National Agriculture Imagery Program (NAIP); the photographs have a positional accuracy of about ±5 meters. The locations of turbines constructed during or prior to August 2009 are based on August 2009 NAIP imagery and turbine locations constructed after August 2009 were based June 2011 NAIP imagery. The location of turbines under construction during June 2011 likely will be less accurate than the location of existing turbines. This data series contributes to an Online Interactive Energy Atlas developed by the U.S. Geological Survey (http://my.usgs.gov/eerma/). The Energy Atlas synthesizes data on existing and potential energy development in Colorado and New Mexico and includes additional natural resource data layers. This information may be used by decisionmakers to evaluate and compare the potential benefits and tradeoffs associated with different energy development strategies or scenarios. Interactive maps, downloadable data layers, comprehensive metadata, and decision-support tools also are included in the Energy Atlas. The format of the Energy Atlas is designed to facilitate the integration of information about energy with key terrestrial and aquatic resources for evaluating resource values and minimizing risks from energy development.

Carr, Natasha B.; Diffendorfer, James B.; Fancher, Tammy; Hawkins, Sarah J.; Latysh, Natalie; Leib, Kenneth J.; Matherne, Anne Marie

2013-01-01

331

Improving wind turbine availability by reliability based maintenance  

Microsoft Academic Search

2) Ingenieurgesellschaft Zuverlässigkeit und Prozessmodellierung (IZP) (Engineering Company for Reliability and Process Simulation), Stauffenbergallee 4, D-01099 DresdenTel.: +49 351 8040-327 • Fax.: -326, h.jung@izp.de Synopsis Modern wind turbines have an availability rate of approx. 98%, smaller wind turbines suffering operational inter- ruptions due to unforeseen causes only once a year on average, whereas larger turbines suffer such operational disturbances more

Berthold Hahn; Harald Jung

332

Measurements of mechanical torque acting on a model wind turbine  

NASA Astrophysics Data System (ADS)

A high precision torque converter is developed and calibrated to measure torques on model wind-turbine generators (small DC motor). By multiplying the measured torque and rotor angular velocity, a direct measurement of the extracted power from the wind turbine can be obtained. This direct method is more advantageous compared to the electrical power measured from the model generator, since it avoids contamination by internal friction, and electric and magnetic losses. The torque converter is mounted on a model wind turbine in a 3 by 3 array (3 rows by 3 columns) of wind turbines in the Corrsin wind tunnel. The power coefficients are obtained as a function of the tip speed ratio. Significant difference between the electrical and mechanical powers is observed, which emphasizes on the importance in using the direct mechanical power measurement. Also, the extracted power by the model turbine is found to be comparable with the power estimated from the kinetic energy flux measured using SPIV.

Kang, Hyung-Suk; Cal, Raul B.; Lebron-Bosques, Jose; Castillo, Luciano; Meneveau, Charles

2009-11-01

333

Wind turbines: is there a human health risk?  

PubMed

The term "Wind Turbine Syndrome" was coined in a recently self-published book, which hypothesized that a multitude of symptoms such as headache and dizziness resulted from wind turbines generating low frequency sound (LFS). The objective of this article is to provide a summary of the peer-reviewed literature on the research that has examined the relationship between human health effects and exposure to LFS and sound generated from the operation of wind turbines. At present, a specific health condition has not been documented in the peer-reviewed literature that has been classified as a disease caused by exposure to sound levels and frequencies generated by the operation of wind turbines. Communities are experiencing a heightened sense of annoyance and fear from the development and siting of wind turbine farms. High-quality research and effective risk communication can advance this course from one of panic to one of understanding and exemplification for other environmental advancements. PMID:23621051

Roberts, Jennifer D; Roberts, Mark A

2013-04-01

334

Aerodynamic Sizing of Vertical-Axis Wind Turbines for Wind Farms.  

National Technical Information Service (NTIS)

This study addresses the issue of whether a large number of small turbines or a small number of large turbines will generate the most total power on a given wind farm. The effects of atmospheric boundary layer, turbine pedestal height, and turbine Reynold...

J. K. Cole

1981-01-01

335

Darrieus wind-turbine airfoil configurations  

SciTech Connect

The purpose of this study was to determine what aerodynamic performance improvement, if any, could be achieved by judiciously choosing the airfoil sections for Darrieus wind turbine blades. Analysis was limited to machines using two blades of infinite aspect ratio, having rotor solidites from seven to twenty-one percent, and operating at maximum Reynolds numbers of approximately three million. Ten different airfoils, having thickness to chord ratios of twelve, fifteen and eighteen percent, were investigated. Performance calculations indicated that the NACA 6-series airfoils yield peak power coefficients at least as great as the NACA four-digit airfoils which have historically been chosen for Darrieus turbines. Furthermore, the power coefficient-tip speed ratio curves were broader and flatter for the 6-series airfoils. Sample calculations for an NACA 63/sub 2/-015 airfoil showed an annual energy output increase of 17 to 27% depending upon rotor solidity, compared to an NACA 0015 airfoil. An attempt was made to account for the flow curvature effects associated with Darrieus turbines by transforming the NACA 63/sub 2/-015 airfoil to an appropriate shape.

Migliore, P.G.; Fritschen, J.R.

1982-06-01

336

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

337

Status of the 4 MW WTS-4 wind turbine  

NASA Astrophysics Data System (ADS)

The WTS-4 is a four-megawatt, horizontal-axis wind turbine presently being fabricated for the U.S. Department of Interior, Bureau of Reclamation, by United Technologies' Hamilton Standard division. This unit, called the System Verification Unit (SVU) will be installed at Medicine Bow, Wyoming, early next spring. The specifications, characteristics and features of the WTS-4 are discussed. The major components-such as rotor, nacelle and tower-are described and their status in the fabrication phase is presented.

Bussolari, R. J.

338

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

2013-04-24

339

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

340

Wind turbine power tracking using an improved multimodel quadratic approach.  

PubMed

In this paper, an improved multimodel optimal quadratic control structure for variable speed, pitch regulated wind turbines (operating at high wind speeds) is proposed in order to integrate high levels of wind power to actively provide a primary reserve for frequency control. On the basis of the nonlinear model of the studied plant, and taking into account the wind speed fluctuations, and the electrical power variation, a multimodel linear description is derived for the wind turbine, and is used for the synthesis of an optimal control law involving a state feedback, an integral action and an output reference model. This new control structure allows a rapid transition of the wind turbine generated power between different desired set values. This electrical power tracking is ensured with a high-performance behavior for all other state variables: turbine and generator rotational speeds and mechanical shaft torque; and smooth and adequate evolution of the control variables. PMID:20434153

Khezami, Nadhira; Benhadj Braiek, Naceur; Guillaud, Xavier

2010-07-01

341

Danish standard wind turbine concept in wind/diesel applications. Draft.  

National Technical Information Service (NTIS)

It is assumed that the Wind Turbines for Wind/Diesel applications fulfil the Danish Standard Wind Turbine Concept for grid connection (see App. A) and that they are provided with stall controlled power regulation and a (simple) interface for external cont...

P. Noergaard

1989-01-01

342

Development of a wind turbine simulator for wind energy conversion systems  

Microsoft Academic Search

A wind turbine simulator for wind energy conversion systems is developed with a view to design, evaluate and implement an actual wind turbine controller. The simulator consists of a 125 hp induction motor which drives a low speed generator and is driven by a 112 kW variable speed drive inverter, and real time control software

L. Chang; R. Doraiswami; T. Boutot; H. Kojabadi

2000-01-01

343

Modelling of Offshore Wind Turbine Wakes with the Wind Farm Program FLaP  

Microsoft Academic Search

The wind farm layout program FLaP estimates the wind speed at any point in a wind farm and the power output of the turbines. The ambient flow conditions and the properties of the turbines and the farm are used as input. The core of the program is an axisymmetric wake model describing the wake behind one rotor. Here an approach

Bernhard Lange; Hans-Peter Waldl; Algert Gil Guerrero; Detlev Heinemann; Rebecca J. Barthelmie

2003-01-01

344

Statistical analysis of wind characteristics at candidate wind-turbine sites  

Microsoft Academic Search

Accurate prediction for a wind turbine facility performance is dependent on appropriate wind characteristics data. This report presents preliminary recommendations of appropriate data recording procedures for initial site evaluation and for large machine performance evaluation. Conclusions are based on autocorrelation, autospectrum persistence, cross-correlation, and coherence analysis of a limited sample of wind speed and turbine power data collected at the

Corotis

1982-01-01

345

A flexible turbine blade for passive blade pitch control in wind turbines  

Microsoft Academic Search

We present a flexible wind turbine blade that effectively pitches itself according to variable wind loading. In contrast to rigid turbine blades, where active controls are often required to pitch blades, the flexible or morphing blade adjusts its geometry passively, eliminating the need for costly electromechanical systems. We analyze the airfoil using a robust and accurate fluid-structure interaction routine, and

David MacPhee; Asfaw Beyene

2011-01-01

346

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

347

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

348

Fault ride through and voltage regulation for grid connected wind turbine  

Microsoft Academic Search

High penetration of wind generation challenges wind turbine operators to supply reliable power and extract optimum power from the wind. Hence, the fault ride through (FRT) capability of wind turbine together with the optimum power tracking and regulation of wind turbine output voltage due to fluctuating nature of the wind becomes essential. In this paper, a method is proposed to

Min Min Kyaw; V. K. Ramachandaramurthy

2011-01-01

349

Grid code requirements concerning connection and operation of wind turbines in Germany  

Microsoft Academic Search

This paper discusses issues of German grid codes relating to wind turbines. With the high utilization of wind power a simultaneous loss of several thousand MW wind generation became a realistic scenario in the German power system. Therefore, the main requirements concern the fault ride through capability of wind turbines. Accordingly, disconnection of wind turbines and wind farms above 15

I. Erlich; U. Bachmann

2005-01-01

350

Electrical\\/mechanical options for variable speed wind turbines  

Microsoft Academic Search

The use of variable speed wind turbines, especially in large-scale utility electricity generating systems, offers a potential improvement in the cost effectiveness of wind energy systems. This paper presents a review of the potential options (including mechanical, electrical\\/mechanical, electrical, and electrical\\/power electronic) open for variable speed wind turbine design and gives some of the advantages and disadvantages of these design

J. F. Manwell; J. G. McGowan; B. H. Bailey

1991-01-01

351

Gas turbine engine component cooling system  

SciTech Connect

In a gas turbine engine including a compressor supported in an annular frame, the frame having a front frame portion extending upstream of the compressor, the front frame having radially inner and outer surfaces, the inner surface defining a flowpath to the compressor, a system is described for cooling an engine component which consists of: the front frame including an aperture extending therethrough; a housing for mounting the engine component therein, including a plurality of heat transfer fins extending outwardly therefrom; and the housing being mounted to the radially outer surface of the front frame so that the heat transfer fins extend through the aperture and into the flowpath.

Colman, M.E.; Goeller, R.E.

1986-09-02

352

Synergistic Effects of Turbine Wakes and Atmospheric Stability on Power Production at an Onshore Wind Farm  

Microsoft Academic Search

This report examines the complex interactions between atmospheric stability and turbine-induced wakes on downwind turbine wind speed and power production at a West Coast North American multi-MW wind farm. Wakes are generated when the upwind flow field is distorted by the mechanical movement of the wind turbine blades. This has two consequences for downwind turbines: (1) the downwind turbine encounters

S Wharton; J K Lundquist; N Marjanovic

2012-01-01

353

Wind Characteristics Analyses and Determination of Appropriate Wind Turbine for Amasra—Black Sea Region, Turkey  

Microsoft Academic Search

In this study, wind characteristics of Amasra were analyzed with hourly wind data collected between 1997 and 2006. Wind characteristics such as monthly average mean speeds, power densities, turbulence intensities, maximum gust, and prevailing wind directions were identified. Weibull distribution model was used to determine energy output of thirty commercial wind turbines ranging from 335 to 3000 kW. Estimated mean

S. A. Akda?; Ö. Güler

2010-01-01

354

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

355

WIND TURBINE DRIVETRAIN TEST FACILITY DATA ACQUISITION SYSTEM  

SciTech Connect

The Wind Turbine Drivetrain Test Facility (WTDTF) is a state-of-the-art industrial facility used for testing wind turbine drivetrains and generators. Large power output wind turbines are primarily installed for off-shore wind power generation. The facility includes two test bays: one to accommodate turbine nacelles up to 7.5 MW and one for nacelles up to 15 MW. For each test bay, an independent data acquisition system (DAS) records signals from various sensors required for turbine testing. These signals include resistance temperature devices, current and voltage sensors, bridge/strain gauge transducers, charge amplifiers, and accelerometers. Each WTDTF DAS also interfaces with the drivetrain load applicator control system, electrical grid monitoring system and vibration analysis system.

Mcintosh, J.

2012-01-03

356

Dynamic characteristics analysis of the offshore wind turbine blades  

NASA Astrophysics Data System (ADS)

The topic of offshore wind energy is attracting more and more attention as the energy crisis heightens. The blades are the key components of offshore wind turbines, and their dynamic characteristics directly determine the effectiveness of offshore wind turbines. With different rotating speeds and blade length, the rotating blades generate various centrifugal stiffening effects. To directly analyze the centrifugal stiffening effect of blades, the Rayleigh energy method (REM) was used to derive the natural frequency equation of the blade, including the centrifugal stiffening effect and the axial force calculation formula. The axial force planes and the first to third order natural frequency planes which vary with the rotating speed and length were calculated in three-dimensional coordinates. The centrifugal stiffening coefficient was introduced to quantitatively study the relationship between the centrifugal stiffening degree and the rotating speed, and then the fundamental frequency correction formula was built based on the rotating speed and the blade length. The analysis results show that the calculation results of the fundamental frequency correction formula agree with the theoretical calculation results. The error of calculation results between them is less than 0.5%.

Li, Jing; Chen, Jianyun; Chen, Xiaobo

2011-03-01

357

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

358

Axial flux, modular, permanent-magnet generator with a toroidal winding for wind turbine applications  

Microsoft Academic Search

Permanent-magnet generators have been used for wind turbines for many years. Many small wind turbine manufacturers use direct-drive permanent-magnet generators. For wind turbine generators, the design philosophy must cover the following characteristics: low cost; light weight; low speed; high torque; and variable speed generation. The generator is easy to manufacture and the design can be scaled up for a larger

E. Muljadi; C. P. Butterfield; Yih-Huei Wan

1998-01-01

359

A Study on the Matching between the Straight Wing Non-articulated Vertical Axis Wind Turbine and the New Wind Turbine Generator  

NASA Astrophysics Data System (ADS)

In the current wind turbine generation system, there are substantial problems such as the maximum power of the wind turbine cannot be obtained under the fluctuating wind speed, high in cost and low in annual net electricity production (due to mismatch between a generator and a wind turbine). A new wind turbine generator optimized for the wind turbine output is presented in order to solve such problems. This wind turbine generator consists of a permanent magnet generator, a reactor and a rectifier, and uses neither a control circuit which requires standby electricity nor a PWM converter having a switching element. By selecting most appropriate combination of the permanent magnet generator having multiple windings and the reactor connected in series with each winding, the maximum output of the wind turbine can be obtained without using a control circuit. The new wind turbine generator was directly coupled with the straight wing non-articulated vertical axis wind turbine (SW-VAWT), and matching of the generator with the wind turbine was examined through field tests. From the test result and review, it has been confirmed that the new wind turbine generator is highly matched with the wind turbine under the fluctuating wind speed.

Siota, Takasi; Isaka, Tsutomu; Sano, Takashi; Seki, Kazuichi

360

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.

361

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

362

Investigating of wind turbines affects on recloser operation in distribution networks  

Microsoft Academic Search

Wind turbines are normally installed on distribution networks and reclosers are one of the main parts of that. Recloser operations are well known in traditional network, but they need more investigations when wind turbines are connected on the other side of the recloser. Existences of wind turbines produce mal-functions of reclosers. In this paper, the affects of the wind turbines

H. Kazemi Karegar; S. Saberi

2010-01-01

363

SYSTEMIC ASSESSMENT AND ANALYSIS OF FACTORS AFFECT THE RELIABILITY OF A WIND TURBINE  

Microsoft Academic Search

Nowadays, the availability of wind turbines usually approaches the 98%. The objective is to increase the turbines availability, by improving the wind turbine reliability especially for offshore plants. The wind turbines reliability is a pivotal factor in the successfully function of a wind power plant. High reliability can be achieved by understanding and minimizing the failures of the system. Maintenance

Pantelis N. Botsaris; D. Pitsa

2012-01-01

364

Design and construction of a simple blade pitch measurement system for small wind turbines  

Microsoft Academic Search

For small wind turbines to be reliable they must have in place good mechanisms to protect themselves against very high winds or sudden removal of load. One common protection method in small wind turbines is that of blade feathering. It is important that the blade feathering mechanism of a small wind turbine is tested before the turbine is installed in

Jonathan Whale

2009-01-01

365

A geographic analysis of wind turbine placement in Northern California  

Microsoft Academic Search

The development of new wind energy projects requires a significant consideration of land use issues. An analytic framework using a Geographic Information System (GIS) was developed to evaluate site suitability for wind turbines and to predict the locations and extent of land available for feasible wind power development. The framework uses rule-based spatial analysis to evaluate different scenarios. The suitability

Laura C. Rodman; Ross K. Meentemeyer

2006-01-01

366

Wind turbine data acquisition and analysis system  

SciTech Connect

Under Department of Energy (DOE) sponsorship, Sandia Laboratories has implemented a program to develop vertical-axis wind turbine (VAWT) systems. One aspect of this program has been the development of an instrumented test site adjacent to Sandia Laboratories' Technical Area I on Kirtland Air Force Base. Three VAWTs are now in operation on this test site. This paper describes the data acquisition and analyses system developed to meet the needs of the VAWT test site. The system employs a 16-bit work-length minicomputer as the major element in a stand-alone configuration. A variety of peripheral devices perform the required data acquisition functions and provide for data display and analysis. Included is a disk-based software operating system that supports a mass storage-file system, high-level language, and auxiliary software procedures.

Stiefeld, B.

1978-07-01

367

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

368

Wind turbine rotor hub and teeter joint  

DOEpatents

A rotor hub is provided for coupling a wind turbine rotor blade and a shaft. The hub has a yoke with a body which is connected to the shaft, and extension portions which are connected to teeter bearing blocks, each of which has an aperture. The blocks are connected to a saddle which envelops the rotor blade by one or two shafts which pass through the apertures in the bearing blocks. The saddle and blade are separated by a rubber interface which provides for distribution of stress over a larger portion of the blade. Two teeter control mechanisms, which may include hydraulic pistons and springs, are connected to the rotor blade and to the yoke at extension portions. These control mechanisms provide end-of-stroke damping, braking, and stiffness based on the teeter angle and speed of the blade.

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

1994-10-11

369

Structural health monitoring of wind turbines  

SciTech Connect

To properly determine what is needed in a structural health monitoring system, actual operational structures need to be studied. We have found that to effectively monitor the structural condition of an operational structure four areas must be addressed: determination of damage-sensitive parameters, test planning, information condensation, and damage identification techniques. In this work, each of the four areas has been exercised on an operational structure. The structures studied were all be wind turbines of various designs. The experiments are described and lessons learned will be presented. The results of these studies include a broadening of experience in the problems of monitoring actual structures as well as developing a process for implementing such monitoring systems.

Simmermacher, T.; James, G.H. III.; Hurtado, J.E.

1997-09-01

370

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

371

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

372

Locations and attributes of wind turbines in Colorado, 2009  

USGS Publications Warehouse

The Colorado wind-turbine data series provides geospatial data for all wind turbines established within the State as of August 2009. Attributes specific to each turbine include: turbine location, manufacturer and model, rotor diameter, hub height, rotor height, potential megawatt output, land ownership, and county. Wind energy facility data for each turbine include: facility name, facility power capacity, number of turbines associated with each facility to date, facility developer, facility ownership, year the facility went online, and development status of wind facility. Turbine locations were derived from August 2009 1-meter true-color aerial photographs produced by the National Agriculture Imagery Program; the photographs have a positional accuracy of about + or - 5 meters. The location of turbines under construction during August 2009 likely will be less accurate than the location of existing turbines. This data series contributes to an Online Interactive Energy Atlas currently (2011) in development by the U.S. Geological Survey. The Energy Atlas will synthesize data on existing and potential energy development in Colorado and New Mexico and will include additional natural resource data layers. This information may be used by decisionmakers to evaluate and compare the potential benefits and tradeoffs associated with different energy development strategies or scenarios. Interactive maps, downloadable data layers, comprehensive metadata, and decision-support tools will be included in the Energy Atlas. The format of the Energy Atlas will facilitate the integration of information about energy with key terrestrial and aquatic resources for evaluating resource values and minimizing risks from energy development.

Carr, Natasha B.; Diffendorfer, Jay E.; Fancher, Tammy S.; Latysh, Natalie E.; Leib, Kenneth J.; Matherne, Anne-Marie; Turner, Christine

2011-01-01

373

Locations and attributes of wind turbines in New Mexico, 2009  

USGS Publications Warehouse

The New Mexico wind-turbine data series provides geospatial data for all wind turbines established within the State as of August 2009. Attributes specific to each turbine include: turbine location, manufacturer and model, rotor diameter, hub height, rotor height, potential megawatt output, land ownership, and county. Wind energy facility data for each turbine include: facility name, facility power capacity, number of turbines associated with each facility to date, facility developer, facility ownership, year the facility went online, and development status of wind facility. Turbine locations were derived from 1-meter August 2009 true-color aerial photographs produced by the National Agriculture Imagery Program; the photographs have a positional accuracy of about + or - 5 meters. The location of turbines under construction during August 2009 likely will be less accurate than the location of existing turbines. This data series contributes to an Online Interactive Energy Atlas currently (2011) in development by the U.S. Geological Survey. The Energy Atlas will synthesize data on existing and potential energy development in Colorado and New Mexico and will include additional natural resource data layers. This information may be used by decisionmakers to evaluate and compare the potential benefits and tradeoffs associated with different energy development strategies or scenarios. Interactive maps, downloadable data layers, comprehensive metadata, and decision-support tools will be included in the Energy Atlas. The format of the Energy Atlas will facilitate the integration of information about energy with key terrestrial and aquatic resources for evaluating resource values and minimizing risks from energy development.

Carr, Natasha B.; Diffendorfer, Jay E.; Fancher, Tammy S.; Latysh, Natalie E.; Leib, Kenneth J.; Matherne, Anne-Marie; Turner, Christine

2011-01-01

374

Midwest Consortium for Wind Turbine Reliability and Optimization  

SciTech Connect

This report provides an overview of the efforts aimed to establish a student focused laboratory apparatus that will enhance Purdue's ability to recruit and train students in topics related to the dynamics, operations and economics of wind turbines. The project also aims to facilitate outreach to students at Purdue and in grades K-12 in the State of Indiana by sharing wind turbine operational data. For this project, a portable wind turbine test apparatus was developed and fabricated utilizing an AirX 400W wind energy converter. This turbine and test apparatus was outfitted with an array of sensors used to monitor wind speed, turbine rotor speed, power output and the tower structural dynamics. A major portion of this project included the development of a data logging program used to display real-time sensor data and the recording and creation of output files for data post-processing. The apparatus was tested in an open field to subject the turbine to typical operating conditions and the data acquisition system was adjusted to obtain desired functionality to facilitate use for student projects in existing courses offered at Purdue University and Indiana University. Data collected using the data logging program is analyzed and presented to demonstrate the usefulness of the test apparatus related to wind turbine dynamics and operations.

Scott R. Dana; Douglas E. Adams; Noah J. Myrent

2012-05-11

375

Output Power Control of Wind Turbine Generator by Pitch Angle Control using Minimum Variance Control  

NASA Astrophysics Data System (ADS)

In recent years, there have been problems such as exhaustion of fossil fuels, e. g., coal and oil, and environmental pollution resulting from consumption. Effective utilization of renewable energies such as wind energy is expected instead of the fossil fuel. Wind energy is not constant and windmill output is proportional to the cube of wind speed, which cause the generated power of wind turbine generators (WTGs) to fluctuate. In order to reduce fluctuating components, there is a method to control pitch angle of blades of the windmill. In this paper, output power leveling of wind turbine generator by pitch angle control using an adaptive control is proposed. A self-tuning regulator is used in adaptive control. The control input is determined by the minimum variance control. It is possible to compensate control input to alleviate generating power fluctuation with using proposed controller. The simulation results with using actual detailed model for wind power system show effectiveness of the proposed controller.

Senjyu, Tomonobu; Sakamoto, Ryosei; Urasaki, Naomitsu; Higa, Hiroki; Uezato, Katsumi; Funabashi, Toshihisa

376

Wind turbine gearbox health monitoring using time-frequency features from multiple sensors  

NASA Astrophysics Data System (ADS)

As wind energy plays an increasingly important role in the US and world electricity supply, maintenance of wind turbines emerges as a critical issue. Because of the remote nature of wind turbines, autonomous and robust health monitoring techniques are necessary. Detecting faults in complex systems such as wind turbine gearboxes remains challenging, even with the recently significant advancement of sensing and signal processing technologies. In this paper, we collect time domain signals from a gearbox test bed on which either a healthy or a faulty gear is installed. Then a harmonic wavelet based method is used to extract time-frequency features. We also develop a speed profile masking technique to account for tachometer readings and gear meshing relationship. Features from multiple sources are then fused together through a statistical weighting approach based on principal component analysis. Using the fused timefrequency features, we demonstrate that different gear faults can be effectively identified through a simple decision making algorithm.

Lu, Y.; Tang, J.

2011-03-01

377

Dynamics modeling and loads analysis of an offshore floating wind turbine  

Microsoft Academic Search

The vast deepwater wind resource represents a potential to use offshore floating wind turbines to power much of the world with renewable energy. Many floating wind turbine concepts have been proposed, but dynamics models, which account for the wind inflow, aerodynamics, elasticity, and controls of the wind turbine, along with the incident waves, sea current, hydrodynamics, and platform and mooring

Jason Mark Jonkman

2007-01-01

378

Dynamics of offshore floating wind turbines-model development and verification  

Microsoft Academic Search

The vast deepwater wind resource represents a potential to use offshore floating wind turbines to power much of the world with renewable energy. Many floating wind turbine concepts have been proposed, but dynamics models, which account for the wind inflow, aerodynamics, elasticity and controls of the wind turbine, along with the incident waves, sea current, hydrodynamics, and platform and mooring

Jason M. Jonkman

2009-01-01

379

Development of a New Procedure for Reliability Modeling of Wind Turbine Generators  

Microsoft Academic Search

A method for determining the impact of wind generation on system reliability is developed. This method combines the effects of wind turbine forced outage rates and varying power output due to wind speed variations. Since individual wind turbines on a windfarm all have an output related to wind speed, each turbine's output cannot be assumed to be independent random variables.

Paul Giorsetto; Kent F. Utsurogi

1983-01-01

380

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

381

The Load Level of Modern Wind Turbines according to IEC 61400-1  

NASA Astrophysics Data System (ADS)

The paper describes some effects on the load level of state-of-the art multi megawatt wind turbines introduced by the new edition of the standard IEC 61400-1:2005 "Wind Turbines - Part 1: Design requirements". Compared to the previous edition, especially the extreme load determination has been modified by applying stochastic and statistical analyses. Within this paper the effect on the overall load level of wind turbines is demonstrated and occurring problems are discussed. Load simulations have been carried out for four state-of-the-art multi-megawatt wind turbines of different design concepts and from different manufacturers. The blade root bending moments and tip deflection have been determined by applying different extrapolation methods. Advantages and disadvantages of these methods and tail fittings for different load components and wind turbine technologies are discussed and interpreted. Further on, the application of the extreme turbulence model is demonstrated. The dependence of the load level on the turbulence intensity and control system, as well as the interaction with extrapolated loads is discussed and limitations outlined. The obtained load level is compared to the overall load level of the turbines according to the previous edition of the standard, IEC 61400-1:1999.

Freudenreich, K.; Argyriadis, K.

2007-07-01

382

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

383

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

384

Evaluatie van de brochure Windturbinegeluid. (Evaluation of the brochure 'Wind turbine noise').  

National Technical Information Service (NTIS)

The brochure 'Windturbinegeluid' (Wind turbine noise) was compiled by Holland Windturbine in cooperation with Lichtveld, Buis and Partners. It contains simple formulas by which noise levels of the rotor, the nacelle of a wind turbine and of the total wind...

J. D. Van der Toorn

1989-01-01

385

Sudden loss of rotor blade from wind power turbine - Calculation of maximax response spectra  

Microsoft Academic Search

The maximum response of a linear one-degree-of-freedom system to a transient phase-shifted truncated sinusoidal load is studied. The system represents the nacelle, tower and foundation of a horizontal axis wind power turbine. The load is the horizontal component of the unbalanced centrifugal force from the remaining blade of the turbine rotor when one blade has suddenly broken off (close to

B. Akesson; S. Sandstrom

1982-01-01

386

Investigation of materials and manufacturing methods for wind turbine blades.  

National Technical Information Service (NTIS)

There is little consensus within the wind turbine industry about the best materials and methods for blade manufacture. The main material used has been glass fibre polyester (GRP) although this material has shown many limitations in the field. Other materi...

D. Corbet

1993-01-01

387

Variable speed generator technology options for wind turbine generators  

NASA Astrophysics Data System (ADS)

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.

1995-05-01

388

Investigation of Excitation Control for Wind-Turbine Generator Stability.  

National Technical Information Service (NTIS)

High speed horizontal axis wind turbine generators with blades on the downwind side of the support tower require special design considerations to handle disturbances introduced by the flow wake behind the tower. Experiments and analytical analyses were ma...

V. D. Gebben

1977-01-01

389

Predicting aerodynamic characteristic of typical wind turbine airfoils using CFD.  

National Technical Information Service (NTIS)

An investigation was conducted into the capabilities and accuracy of a representative computational fluid dynamics code to predict the flow field and aerodynamic characteristics of typical wind-turbine airfoils. Comparisons of the computed pressure and ae...

W. P. Wolfe S. S. Ochs

1997-01-01

390

Matching Wind Turbine Rotors and Loads: Computational Methods for Designers.  

National Technical Information Service (NTIS)

This report provides a comprehensive method for matching wind energy conversion system (WECS) rotors with the load characteristics of common electrical and mechanical applications. The user must supply: (1) turbine aerodynamic efficiency as a function of ...

J. B. Seale

1983-01-01

391

Fatigue Evaluation of WTS-3 Wind Turbine Blade and Retention.  

National Technical Information Service (NTIS)

The WTS-3 wind turbine blade and retention computed stress levels are compared to material properties, and potentially fatigue critical areas are identified. For the blade, these are flatwise spar stresses, and blade shell flatwise stresses. It is not pos...

A. I. Gustavsson A. F. Blom

1987-01-01

392

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

393

Wind turbine acoustics research bibliography with selected annotation  

NASA Astrophysics Data System (ADS)

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

394

Investigation of Various Wind Turbine Drivetrain Condition Monitoring Techniques (Presentation)  

SciTech Connect

This presentation was given at the 2011 Wind Turbine Reliability Workshop sponsored by Sandia National Laboratories in Albuquerque, NM on August 2-3, 2011. It discusses work for the Gearbox Reliability Collaborative including downtime caused by turbine subsystems, annual failure frequency of turbine subsystems, cost benefits of condition monitoring (CM), the Gearbox Reliability Collaborative's condition monitoring approach and rationale, test setup, and results and observations.

Sheng, S.

2011-08-01

395

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

396

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.

397

A Variable Speed Wind Turbine Control Strategy to Meet Wind Farm Grid Code Requirements  

Microsoft Academic Search

This paper presents a new operational strategy for a small scale wind farm which is composed of both fixed and variable speed wind turbine generator systems (WTGS). Fixed speed wind generators suffer greatly from meeting the requirements of new wind farm grid code, because they are largely dependent on reactive power. Integration of flexible ac transmission systems (FACTS) devices is

S. M. Muyeen; Rion Takahashi; Toshiaki Murata; Junji Tamura

2010-01-01

398

Comparative study of the behavior of wind-turbines in a wind farm  

Microsoft Academic Search

The Sotavento wind farm is an experimental wind farm which has different types of wind turbines. It is located in an area whose topography is moderately complex, and where wake effects can be significant. One of the objectives of Sotavento wind farm is to compare the performances of the different machines; particularly regarding power production, maintenance and failures. However, because

Emilio Migoya; Antonio Crespo; Javier García; Fermín Moreno; Fernando Manuel; Ángel Jiménez; Alexandre Costa

2007-01-01

399

A neural network based wind speed estimator for a wind turbine control  

Microsoft Academic Search

Variable speed wind generation systems are more attractive than fixed-speed systems because of the more efficient energy production improved power quality, and improved dynamic performance during grid disturbances. In this sense, to implement maximum wind power extraction, most controller designs of the variable-speed wind turbine generators employ anemometers to measure wind speed in order to derive the desired optimal shaft

Oscar Barambones; Jose Maria Gonzalez de Durana; Enrique Kremers

2010-01-01

400

An Assessment of Wind Turbine Characteristics and Wind Energy Characteristics for Electricity Production  

Microsoft Academic Search

This work is an analysis of wind turbine characteristics and wind energy characteristics of four regions around Elazig, Turkey, namely Maden, Agin Elazig and Keban. Wind speed data and wind direction in measured hourly time-series format is statistically analyzed based on 6 years between 1998 and 2003. The probability density distributions are derived from time-series data and distributional parameters are

E. Kavak Akpinar; S. Akpinar

2006-01-01

401

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

402

An evaluation of wind turbine blade cross section analysis techniques.  

SciTech Connect

The blades of a modern wind turbine are critical components central to capturing and transmitting most of the load experienced by the system. They are complex structural items composed of many layers of fiber and resin composite material and typically, one or more shear webs. Large turbine blades being developed today are beyond the point of effective trial-and-error design of the past and design for reliability is always extremely important. Section analysis tools are used to reduce the three-dimensional continuum blade structure to a simpler beam representation for use in system response calculations to support full system design and certification. One model simplification approach is to analyze the two-dimensional blade cross sections to determine the properties for the beam. Another technique is to determine beam properties using static deflections of a full three-dimensional finite element model of a blade. This paper provides insight into discrepancies observed in outputs from each approach. Simple two-dimensional geometries and three-dimensional blade models are analyzed in this investigation. Finally, a subset of computational and experimental section properties for a full turbine blade are compared.

Paquette, Joshua A.; Griffith, Daniel Todd; Laird, Daniel L.; Resor, Brian Ray

2010-03-01

403

Performance optimization of a dual-rotor wind turbine system  

Microsoft Academic Search

We are building an efficient and smart wind turbine system. The significant features of this turbine are its dual rotor blade system which is positioned horizontally at upwind and downwind locations, its drive train which is installed horizontally inside the tower with a new efficient induction generator, and its control and safety systems. The project focuses mainly on the methodology

Riadh W. Y. Habash; Voicu Groza; Pierre Guillemette

2010-01-01

404

Active and Passive Lift Force Augmentation Techniques on Wind Turbines  

NASA Astrophysics Data System (ADS)

The paper presents a short review of active and passive lift force augmentation concepts for wind turbines. The few models presented were analyzed using CFD to determine their potential in terms of improved performance of wind turbines. There will also be presented and computational aspects related to modeling active and passive control systems. Numerical simulations are based on RANS (Reynolds averaged Navier-Stokes) equations model supplemented with a suitable turbulence model; in our case turbulence models used were k-? and k-? SST.

Frunzulic?, F.; Dumitrescu, H.; Mahu, R.; Preotu, O.

2011-09-01

405

Insect attraction to wind turbines: does colour play a role?  

Microsoft Academic Search

The phenomenon of wildlife mortality at wind turbine installations has been generating increasing concern, both for the continued\\u000a development of the wind industry and for local ecology. While an increase in aerial insectivore activity in the vicinity resulting\\u000a from insect attraction to turbines remains a strong possibility, little research exists on the possible causes for such events.\\u000a In this paper,

C. V. Long; J. A. Flint; P. A. Lepper

2011-01-01

406

The Influence of Wind Characteristic on Aeroelastic Stability for Wind Turbine Blades  

Microsoft Academic Search

Modern wind turbine blades become larger and larger. Careful analysis in the blade development is needed to avoid unstable vibration of the blade. In this paper, a numerical model is developed for investigating the aeroelastic response of a single wind turbine blade. The structural dynamic model is developed based on the Hamilton variation principle combining with FEM. Each element is

Hong Liangyou; Jiang Dongxiang

2009-01-01

407

Remote sensing of the wind and turbulence characteristics at the heights of modern wind turbines  

Microsoft Academic Search

Remote sensing estimates of wind resource potential and turbulence structure of the boundary layer at the heights of turbine rotors is very important as the height reached by commercial turbines increases up to 200- 250 m to take advantage of stronger wind speeds at higher altitudes. The fine temporal and spatial resolution of Doppler lidar observations can provide near-continuous information

Y. L. Pichugina; R. M. Banta; N. D. Kelley; W. A. Brewer

2008-01-01

408

Active aerodynamic load control on wind turbines: Aeroservoelastic modeling and wind tunnel  

Microsoft Academic Search

This thesis investigates particular concepts and technologies that can alleviate fatigue loads on wind turbines by using distributed active aerodynamic devices on the blades, a concept briefly referred to as `smart blades'. Firstly, published research work on smart control devices is reviewed, and the pros and cons for the application on wind turbines is discussed. Then an introduction to the

A. Barlas

2011-01-01

409

Adaptive torque control of variable speed wind turbines  

NASA Astrophysics Data System (ADS)

Wind is a clean, renewable resource that has become more popular in recent years due to numerous advances in technology and public awareness. Wind energy is quickly becoming cost competitive with fossil fuels, but further reductions in the cost of wind energy are necessary before it can grow into a fully mature technology. One reason for higher-than-necessary cost of the wind energy is uncertainty in the aerodynamic parameters, which leads to inefficient controllers. This thesis explores an adaptive control technique designed to reduce the negative effects of this uncertainty. The primary focus of this work is a new adaptive controller that is designed to resemble the standard non-adaptive controller used by the wind industry. The standard controller was developed for variable speed wind turbines operating below rated power. The new adaptive controller uses a simple, highly intuitive gain adaptation law intended to seek out the optimal gain for maximizing the turbine's energy capture. It is designed to work even in real, time-varying winds. The adaptive controller has been tested both in simulation and on a real turbine, with numerous experimental results provided in this work. Simulations have considered the effects of erroneous wind measurements and time-varying turbine parameters, both of which are concerns on the real turbine. The adaptive controller has been found to operate as desired under realistic operating conditions, and energy capture has increased on the real turbine as a result. Theoretical analyses of the standard and adaptive controllers were performed, as well, providing additional insight into the system. Finally, a few extensions were made with the intent of making the adaptive control idea even more appealing in the commercial wind turbine market.

Johnson, Kathryn E.

410

Using a new characterization of turbulent wind for accurate correlation of wind turbine response with wind speed  

SciTech Connect

The turbulence encountered by a point on a rotating wind turbine blade has characteristics that in some important respects are different from those measured by a stationary anemometer. The conventional one-peaked continuous spectrum becomes, broadly, a two-peaked spectrum that in addition contains a set of narrow-band spikes of turbulence energy, one centered on the frequency of rotor rotation and the others centered on multiples of that frequency. The rotational sampling effect on wind spectra is quantified using measurements of wind velocity by anemometers on stationary crosswind circular arrays. Characteristics of fluctuating wind are compared to measured fluctuations of bending moments of the rotor blades and power output fluctuations of a horizontal-axis wind turbine at the same site. The wind characteristics and the correlations between wind fluctuations and wind turbine fluctuations provide a basis for improving turbine design, siting, and control. 6 refs., 11 figs., 1 tab.

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

1987-09-01

411

Influence of wind turbine flexibility on loads and power production  

NASA Astrophysics Data System (ADS)

Most aeroelastic codes used today assume small blade deflections and application of loads on the undeflected structure. However, with the design of lighter and more flexible wind turbines, this assumption is not obvious. By scaling the system mass and stiffness properties equally, it is possible to compare wind turbines of different degrees of slenderness and at the same time keep system frequencies the same in an undeformed state. The developed model uses the commercial finite element system MSC. Marc, focused on non-linear design and analysis, to predict the structural response. The aerodynamic model AERFORCE, used to transform the wind to loads on the blades, is a blade element momentum model. A comparison is made between different slenderness ratios in three wind conditions below rated wind speed. The results show that large blade deflections have a major influence on power production and the resulting structural loads and must be considered in the design of very slender turbines. Copyright

Ahlström, Anders

2006-05-01

412

The inception of OMA in the development of modal testing technology for wind turbines  

Microsoft Academic Search

Wind turbines are immense, flexible structures with aerodynamic forces acting on the rotating blades at harmonics of the turbine rotational frequency. These harmonics are comparable to the modal frequencies of the structure. Predicting and experimentally measuring the modal frequencies of wind turbines have been important to their successful design and operation. Performing modal tests on wind turbine structures over 100

Thomas G. Carne; George H. James

2010-01-01

413

The inception of OMA in the development of modal testing technology for wind turbines  

Microsoft Academic Search

Wind turbines are immense, flexible structures with aerodynamic forces acting on the rotating blades at harmonics of the turbine rotational frequency. These harmonics are comparable to the modal frequencies of the structure. Predicting and experimentally measuring the modal frequencies of wind turbines have been important to their successful design and operation. Performing modal tests on wind turbine structures over 100m

Thomas G. Carne; George H. James III

2010-01-01

414

Study of the turbulent characteristics of the near-wake field of a medium-sized wind turbine operating in high wind conditions  

SciTech Connect

The near-wake turbulent structure that is downwind of a medium-sized, horizontal axis wind turbine at a distance of one rotor diameter is discussed. The experimental site is the Samos Island Wind Park comprising nine wind turbines installed on the top of a 400 m-high saddle. The analysis is based on experimental data obtained mainly under strong wind conditions by two masts erected upstream and downstream of a wind turbine. The field of wind turbulence is examined both in integral and spectral form. Consideration of the perturbation produced by the tower construction is crucial in the interpretation of results. Observations show that the turbulent field varies from the edge to the center of the wake and strongly depends on the incident wind speed. Increased turbulent levels are observed near the blade tips, with evidence of a similar trend around the hub height for all wind speeds. Decreases of wind turbulence are observed in mid frequencies inside the wake due to the reduced shear associated with the flat crosswind velocity profile. This effect seems to dominate in the variation of the integral values of the longitudinal wind component variance. The low frequency portion of wind spectra reverses behavior in high wind speeds, i.e., an increase in energy relative to background values is observed. This is probably due to the shape of the turbine characteristic power curve. Cross-wind profiles of turbulent shear stresses at the lower boundary of the wake are also discussed. 15 refs., 15 figs., 4 tabs.

Papadopoulos, K.H.; Helmis, C.G.; Soilemes, A.T.; Papageorgas, P.G.; Asimakopoulos, D.N. [Lab. of Meteorology, Athens (Greece)

1995-07-01

415

Applying canopy flow model for estimation of wind turbine wake  

NASA Astrophysics Data System (ADS)

For the planning of large offshore wind farm the optimal spatial placing of wind turbines as well as wind farms relatively to each other is highly important to reduce the wake losses of energy. Conventional instrumental investigations of airflow characteristics around and inside an offshore wind farm aimed at understanding of far-wake behavior are very difficult and expensive. Computational fluid dynamic (CFD) models can provide the information on spatial patterns of wind and turbulence and thus, help to develop the optimal wind farm design. With limited level of model resolution, however, there is still a problem of how to describe the effect of a wind turbine itself on air flow. Having this problem solved the joint effects of a given number of wind turbines could be easily estimated. In present work, to describe the influence of a wind turbine on the flow a coupled canopy-atmospheric boundary-layer model SCADIS is implemented. It has been shown that this model, based on two-equation closure and modified to account for plant drag, is able to simulate airflow through a wide range of vegetation reasonably. In the numerical experiment with SCADIS the turbine's rotor was replaced by a disk of limited thickness, with diameter (D) and location of real rotor but with properties of vegetation. Aerodynamic drag values for this rotor with some 'plant' surface density can be derived from the trust coefficient Cp of the wind turbine of interest. Model results were compared with measurements from the Danish offshore wind farm Vindeby consisted of 11 Bonus 450 kW turbines (hub height and rotor diameter are 38 m and 35 m, respectively). The comparison show that the approach can describe well the single- and double-wake cases (at distance 9.6D behind the last turbine), and quintuple-wake case (at distance 8.6D). Taking in account relatively low the computing time demands of the approach, it is a promising tool for further studies of wakes of offshore wind turbines of any size and composition.

Sogachev, A.; Joergensen, H. E.; Mann, J.; Frandsen, S.; Ott, S.

2008-12-01

416

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

417

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

418

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

419

Influence of wind–waves energy transfer on the impulsive hydrodynamic loads acting on offshore wind turbines  

Microsoft Academic Search

This paper draws some preliminary considerations about the direct wind effects on the kinematics and dynamics of steep extreme waves propagating near offshore wind turbines. Most of the hydrodynamic load models currently employed in designing offshore wind turbines take into account only indirectly the role of the wind. In fact, once the sea severity upon a certain wind speed is

Enzo Marino; Claudio Borri; Claudio Lugni

2011-01-01

420

LES investigation of turbine spacing effects in wind farms  

NASA Astrophysics Data System (ADS)

We study turbine spacing and layout effects in large wind farms using large-eddy simulation (LES) with the actuator disk model to represent individual turbines. The actuator disk model is implemented in our second-order accurate immersed boundary finite-difference solver using the discrete delta functions to interpolate the velocities on the disk and distribute the body forces to the surrounding fluid points. For aligned wind farms, the effects of the streamwise and spanwise spacings on the extracted power and turbulence intensities in the vicinity of the turbines are systematically studied. A model for the effective roughness length is also developed based on the present numerical results. As part of our future work, the effect of turbine spacing in staggered wind farms will be investigated.

Yang, Xiaolei; Sotiropoulos, Fotis

2011-11-01

421

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

422

Nonlinear parametric instability of wind turbine wings  

NASA Astrophysics Data System (ADS)

Nonlinear rotor dynamic is characterized by parametric excitation of both linear and nonlinear terms caused by centrifugal and Coriolis forces when formulated in a moving frame of reference. Assuming harmonically varying support point motions from the tower, the nonlinear parametric instability of a wind turbine wing has been analysed based on a two-degrees-of-freedom model with one modal coordinate representing the vibrations in the blade direction and the other vibrations in edgewise direction. The functional basis for the eigenmode expansion has been taken as the linear undamped fixed-base eigenmodes. It turns out that the system becomes unstable at certain excitation amplitudes and frequencies. If the ratio between the support point motion and the rotational frequency of the rotor is rational, the response becomes periodic, and Floquet theory may be used to determine instability. In reality the indicated frequency ratio may be irrational in which case the response is shown to be quasi-periodic, rendering the Floquet theory useless. Moreover, as the excitation frequency exceeds the eigenfrequency in the edgewise direction, the response may become chaotic. For this reason stability of the system has in all cases been evaluated based on a Lyapunov exponent approach. Stability boundaries are determined as a function of the amplitude and frequency of the support point motion, the rotational speed, damping ratios and eigenfrequencies in the blade and edgewise directions.

Larsen, J. W.; Nielsen, S. R. K.

2007-01-01

423

Modifying power curve of Variable Speed Wind Turbines by Performance Evaluation of Pitch-Angle and Rotor Speed Controllers  

Microsoft Academic Search

The Power curve of wind turbine ignores the dynamic behavior of the wind and represents the wind turbine power as a function of the average wind speed. Power curve is not an adequate tool for estimating the power of variable speed wind turbines. Because, in addition to average wind speed, the output power of these turbines is highly dependent on

M. H. Zamani; G. H. Riahy; A. J. Ardakani

2007-01-01

424

Analysis of the effects of integrating wind turbines into a conventional utility: a case study. Revised final report  

Microsoft Academic Search

The impact on a utility incorporating wind turbine generation due to wind speed sampling frequency, wind turbine performance model, and wind speed forecasting accuracy is examined. The utility analyzed in this study was the Los Angeles Department of Water and Power, and the wind turbine assumed was the MOD-2. The sensitivity of the economic value of wind turbine generation to

M. K. Goldenblatt; H. L. Wegley; A. H. Miller

1983-01-01

425

Analysis of the effects of integrating wind turbines into a conventional utility: a case study. Final report  

Microsoft Academic Search

The impact on a utility incorporating wind turbine generation due to wind speed sampling frequency, wind turbine performance model, and wind speed forecasting accuracy is examined. The utility analyzed in the study was the Los Angeles Department of Water and Power and the wind turbine assumed was the MOD-2. The sensitivity of the economic value of wind turbine generation to

M. K. Goldenblatt; H. L. Wegley; A. H. Miller

1982-01-01

426

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

427

Smoothing Output Power of a Doubly Fed Wind Turbine with an Energy Storage System  

Microsoft Academic Search

Wind energy sources are characterized by irregularity and unpredictability. In normal operation, random properties of wind and blade rotational turbulence can produce unwanted fluctuation on the voltage and power supplied into the system. Power output of a wind turbine is a function of wind speed. Wind turbine is a source of power fluctuations due to the nature of wind speed.

M. Aktarujjaman; M. A. Kashem; M. Negnevitsky; G. Ledwich

428

Fatigue case study and reliability analyses for wind turbines  

Microsoft Academic Search

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

Herbert J. Sutherland; Paul S. Veers

1994-01-01

429

Wind turbines in icing conditions: performance and prediction  

Microsoft Academic Search

Icing on structures is an important issue for wind energy developments in many regions of the world. Unfortunately, information about icing conditions is mostly rare due to a lack of measurements. Additionally, there is not much known about the operation of wind turbines in icing conditions. It is the aim of the current study to investigate the effect of icing

S. Dierer; R. Oechslin; R. Cattin

2011-01-01

430

Adaptive Torque Control of Variable Speed Wind Turbines.  

National Technical Information Service (NTIS)

The primary focus of this work is a new adaptive controller that is designed to resemble the standard non-adaptive controller used by the wind industry for variable speed wind turbines below rated power. This adaptive controller uses a simple, highly intu...

K. E. Johnson

2004-01-01

431

Exploration of the vortex wake behind of wind turbine rotor  

Microsoft Academic Search

The present paper describes a wind tunnel study of flow downstream a small horizontal axis wind turbine (HAWT). The experimental investigations were carried out with the use of particle image velocimetry (PIV). To obtain the flow field in the rotating frame of reference, the phase-locked technique was applied. Explorations were carried out in azimuth planes with different angles. The 3D

F Massouh; I Dobrev

2007-01-01

432

Model for simulating rotational data for wind turbine applications  

NASA Astrophysics Data System (ADS)

This document describes a wind simulation model to be used in relation to wind turbine operations. The model is a computer code written in FORTRAN 77. The model simulates turbulence and mean wind effects as they are experienced at a rotating point on the blade of either a horizontal-axis wind turbine (HAWT) or a vertical-axis wind turbine (VAWT). The model is fast, requiring 15 to 120 seconds of VAX execution time to produce a simulation and related statistics. The model allows the user to set a number of wind parameters so that he may evaluate the uncertainty of model results as well as their typical values. When this capability is combined with short execution time, the user can quickly produce a number of simulations based on reasonable variation of input parameters and can use these simulations to obtain a range of wind turbine responses to the turbulence. This ability is important because some of the wind parameters that cannot be precisely evaluated should be prescribed over a range of values. This document is essentially a user's guide. Its features include theoretical derivations, samples of output, comparisons of measured and modeled results, a listing of the FORTRAN code, a glossary for the code, and the input and output of a sample run.

Powell, D. C.; Connell, J. R.

1986-04-01

433

Pitch-controlled variable-speed wind turbine generation  

Microsoft Academic Search

This paper covers the operation of variable-speed wind turbines with pitch control. The system the authors considered is controlled to generate maximum energy while minimizing loads. The maximization of energy was only carried out on a static basis and only drive train loads were considered as a constraint. In low to medium wind speeds, the generator and the power converter

Eduard Muljadi; C. P. Butterfield

2001-01-01

434

A 34-meter VAWT (Vertical Axis Wind Turbine) point design  

Microsoft Academic Search

The Wind Energy Division at Sandia National Laboratories recently completed a point design based on the 34-m Vertical Axis Wind Turbine (VAWT) Test Bed. The 34-m Test Bed research machine incorporates several innovations that improve Darrieus technology, including increased energy production, over previous machines. The point design differs minimally from the Test Bed; but by removing research-related items, its estimated

T. D. Ashwill; D. E. Berg; H. M. Dodd; M. A. Rumsey; H. J. Sutherland; P. S. Veers

1991-01-01

435

Predicting aerodynamic characteristic of typical wind turbine airfoils using CFD  

Microsoft Academic Search

An investigation was conducted into the capabilities and accuracy of a representative computational fluid dynamics code to predict the flow field and aerodynamic characteristics of typical wind-turbine airfoils. Comparisons of the computed pressure and aerodynamic coefficients were made with wind tunnel data. This work highlights two areas in CFD that require further investigation and development in order to enable accurate

W. P. Wolfe; S. S. Ochs

1997-01-01

436

Predicting Aerodynamic Characteristics of Typical Wind Turbine Airfoils Using CFD  

Microsoft Academic Search

An investigation was conducted into the capabilities and accuracy of a representa- tive computational fluid dynamics code to predict the flow field and aerodynamic characteristics of typical wind-turbine airfoils. Comparisons of the computed pres- sure and aerodynamic coefficients were made with wind tunnel data. This work highlights two areas in CFD that require further investigation and development in order to

Walter P. Wolfe

1997-01-01

437

Blade pitch angle control for large wind turbines  

Microsoft Academic Search

This patent describes a blade pitch angle control system for a wind turbine generator comprising a rotor having variable pitch airfoil blades fixed thereto and driving an electric generator through a drive train. The blade pitch angle control system includes control means providing a reference signal indicative of desired blade pitch angle at less than rated wind speed conditions. The

K. I. Harner; F. R. Niessen; R. Sherman

1987-01-01

438

Yawing of wind turbines with blade cyclic-pitch variation  

Microsoft Academic Search

The control system horizontal axis wind turbine is discussed. It incorporates two features: the application of blade cyclic pitch variation adopted from rotorcraft technology, and the use of yaw angle control, not only for wind direction following, but also for rotor speed or torque control. Cyclic pitch variation in a two-bladed rotor relieves the blades of all the gyroscopic and

K. H. Hohenemser; A. H. P. Swift; D. A. Peters

1981-01-01

439

Pareto distribution for extreme loads on wind turbines  

Microsoft Academic Search

Extreme loads from 50-years wind and gusts play an important role in the design of wind turbines. Normally these loads are derived from simulated time series by identifying the absolute extreme values, leaving a high amount of uncertainty and chance in these design parameters. Here we describe a method to determine statistically well founded extreme loads on the basis of

M. Hänler; U. Ritschel; I. Warnke

440

Abrasive flow machining of turbine engine components  

SciTech Connect

A technique used for improving the performance and durability of aircraft turbine engines by flowing abrasive media through critical components is described. The process is abrasive only where the flow is restricted: the extrusion area (the process is also known as extrusion honing). Process parameters including extrusion pressure and the volume of flow are presented, and the tooling and media are covered. The abrasive grains are mostly made of silicon carbide, although boron carbide, aluminum oxide, and diamond may also be used. Some abrasive-flow machining applications in aerospace involve removal of the thermal recast layer in the lasered cooling holes of blades and disks, deburring fuel spray nozzles, and polishing cast surfaces of blades, compressor wheels, and impellers. 6 refs.

Rhoades, L.J. (Extrude Hone Corp., Irwin, PA (USA))

1990-01-01

441

Mechanical Stresses in Fixed-Speed Wind Turbines Due to Network Disturbances  

Microsoft Academic Search

Electrical faults and other network disturbances generate transients of the generator electromagnetic torque, which result in significant stresses for the wind turbine (WT) mechanical system and may also have a detrimental effect on the fatigue life of important drive train components, such as the gearbox. In this paper the effect of faults and other disturbances, common in rural medium voltage

S. A. Papathanassiou; M. P. Papadopoulous

2001-01-01

442

Optimizing the Annual Energy Production of Doubly-Fed Induction Generator Based Wind Turbines  

Microsoft Academic Search

This paper presents a detailed methodology for the estimation and optimization of the annualized performances of wind turbines equipped with doubly-fed induction generators (DFIG). The method takes into account the losses and ratings of different system components : gearbox, DFIG, and power converters. The influence of the DC-bus voltage limit of the power converters on the annual energy yield reduction

D. Aguglia; R. Wamkeue; P. Viarouge; J. Cros

2007-01-01

443

Model 0A Wind Turbine Generator FMEA (Failure Modes and Effects Analysis).  

National Technical Information Service (NTIS)

The results of Failure Modes and Effects Analysis (FMEA) conducted for the Wind Turbine Generators are presented. The FMEA was performed for the functional modes of each system, subsystem, or component. The single-point failures were eliminated for most o...

W. E. Klein V. R. Lalli

1989-01-01

444

Mechanical stresses in fixed-speed wind turbines due to network disturbances  

Microsoft Academic Search

Electrical faults and other network disturbances generate transients of the generator electromagnetic torque which result in significant stresses for the wind turbine (WT) mechanical system and may also have a detrimental effect on the fatigue life of important drive train components, such as the gearbox. In this paper, the effect of faults and other disturbances, common in rural medium voltage

Stavros A. Papathanassiou; Michael P. Papadopoulos

2001-01-01

445

Television Interference due to Electromagnetic Scattering by the MOD2 Wind Turbine Generators  

Microsoft Academic Search

The characterization and identification of electromagnetic interference created by the slowly rotating blade of a MOD-2 wind turbine generator (WTG) is investigated. Field measurement data supports the thesis that at ground level the near field scattered component is an amplitude modulated secondary signal. A prediction methodology to define zones of interference to television broadcast reception is presented.

K. H. Cavcey; L. Y. Lee; M. A. Reynolds

1984-01-01

446

Power quality measurements performed on a low-voltage grid equipped with two wind turbines  

Microsoft Academic Search

The power quality of a low-voltage grid with two wind turbines is investigated. Slow voltage variations as well as transients and harmonics are measured and analysed. Furthermore, the spectrum of the power is determined so that the presence of periodic power components can be investigated. Although periodic power fluctuations reaching 10% of the rated power are registered, voltage variations are

T. Thiringer

1996-01-01

447

Television Interference Due to Electromagnetic Scattering by the MOD2 Wind Turbine Generators  

Microsoft Academic Search

The characterization and identification of electromagnetic interference created by the slowly rotating blade of a MOD-2 wind turbine generator (WTG) is investigated. Field measurement data supports the thesis that at ground level the near field scattered component is an amplitude modulated secondary signal. A prediction methodology to define zones of interference to television broadcast reception is presented.

K. H. Cavcey; L. Y. Lee; M. A. Reynolds

1984-01-01

448

Modeling and control of variable-speed wind-turbine drive-system dynamics  

Microsoft Academic Search

When designing control for variable-speed wind turbines, one deals with highly resonant, nonlinear dynamic systems subject to random excitation, i.e., wind turbulence. This requires good knowledge of the dynamics to be controlled, particularly when combined with the increasingly common “soft” concept of lightweight, flexible constructional components; it creates cost advantages compared to more material-consuming rigid constructions, but also results in

P. Novak; T. Ekelund; I. Jovik; B. Schmidtbauer

1995-01-01

449

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.

2011-01-01

450

A comparative calculation of the wind turbines capacities on the basis of the L– ? criterion  

Microsoft Academic Search

Usually, wind sites are equipped with fast-running Horizontal Axis Wind Turbines of the airscrew type, which has a high efficiency. In this article, the argument is put forward that the choice of a wind turbine must not be based only on high efficiency. We propose a comparative criterion adapted to the comparison of a horizontal axis wind turbine with a

Jean-Luc Menet; Laurent-Charles Valdès; Bruno Ménart

2001-01-01

451

The disturbance accommodating control for variable-pitch variable-speed wind turbine speed regulation  

Microsoft Academic Search

A disturbance regulation feedback loop is added to state space controller in order to adapt the wind disturbances for wind turbine control systems, and a robust wind turbine speed controller is designed. The dynamic performance of wind turbine speed regulation is improved and mechanical loads are alleviated by proper design of the state-space feedback and DAC feedback parameters. The simulation

Shitao Wang; Xiaoguang Jin; Dehua Zhang; Zhengyu Lu

2010-01-01

452

Voltage dip ride-through control of direct-drive wind turbines  

Microsoft Academic Search

With an increasing amount of wind energy installed, the behaviour of wind turbines during grid disturbances becomes more important. Grid operators require that wind turbines stay connected to the grid during voltage dips. This contribution presents a controller that can be used to keep direct-drive wind turbines with permanent magnet generator connected to the grid during voltage disturbances. The behaviour

Johan Morren; Jan T. G. Pierik; S. W. H. de Haan

2004-01-01

453

DC bus control of variable speed wind turbine using a buck-boost converter  

Microsoft Academic Search

For most of the peak power extraction methods in wind turbine generation system described in the current literature, it is necessary to know the wind turbine's maximum power curve and the wind speed measurement. These methods used the maximum power curve obtained via simulations or tests for individual wind turbines. This makes these methods difficult and expensive to implement in

T. Tafticht; K. Agbossou; A. Cheriti

2006-01-01

454

Design of a wind turbine pitch angle controller for power system stabilisation  

Microsoft Academic Search

The design of a PID pitch angle controller for a fixed speed active-stall wind turbine, using the root locus method is described in this paper. The purpose of this controller is to enable an active-stall wind turbine to perform power system stabilisation. For the purpose of controller design, the transfer function of the wind turbine is derived from the wind

Clemens Jauch; Syed M. Islam; Poul Sørensen; Birgitte Bak Jensen

2007-01-01

455

Performance of a 3 kW wind turbine generator with variable pitch control system  

Microsoft Academic Search

A prototype 3kW horizontal upwind type wind turbine generator of 4m in diameter has been designed and examined under real wind conditions. The machine was designed based on the concept that even small wind turbines should have a variable pitch control system just as large wind turbines, especially in Japan where typhoons occur at least once a year. A characteristic

Baku M. Nagai; Kazumasa Ameku; Jitendro Nath Roy

2009-01-01

456

An assessment of the economic impact of the wind turbine supply chain in Illinois  

SciTech Connect

The enormous growth of wind energy in Illinois and around the country has led to a shortage of wind turbines. Turbine manufacturers have sold out their capacity into 2010. To the extent that Illinois manufacturing can integrate itself into the wind turbine supply chain, Illinois can enjoy the economic benefits from both having wind farms and supplying the parts to build them. (author)

Carlson, J. Lon; Loomis, David G.; Payne, James

2010-08-15

457

Indirect effects of lightning on wind turbines using EMTP-RV  

Microsoft Academic Search

This paper is concerned with the protection of wind turbines against the indirect effects of lightning. Lightning damages involving wind turbines have come to be regarded with increasing concern. The wind power generation is rapidly growing in Portugal, but still there are few studies regarding the lightning protection of wind turbines using models of the Electro-Magnetic Transients Program (EMTP). Hence,

R. B. Rodrigues; V. M. F. Mendes; J. P. S. Catalao

2011-01-01

458

Utility Operational Experience on the NASA/DOE MOD-0A 200-kw Wind Turbine.  

National Technical Information Service (NTIS)

The Mod-0A 200 wind turbine was designed and fabricated as part of the Federal Wind Energy Program. Early wind turbine operation and performance data were obtained while gaining initial experience in the operation of large, horizontal axis wind turbines i...

J. C. Glasgow W. H. Robbins

1979-01-01

459

Electric power from vertical-axis wind turbines  

NASA Astrophysics Data System (ADS)

Significant advancements have occurred in vertical axis wind turbine (VAWT) technology for electrical power generation over the last decade; in particular, well-proven aerodynamic and structural analysis codes have been developed for Darrieus-principle wind turbines. Machines of this type have been built by at least three companies, and about 550 units of various designs are currently in service in California wind farms. Attention is presently given to the aerodynamic characteristics, structural dynamics, systems engineering, and energy market-penetration aspects of VAWTs.

Touryan, K. J.; Strickland, J. H.; Berg, D. E.

1987-12-01

460

Modeling and Control of Wind Turbine Tower Vibrations  

NASA Astrophysics Data System (ADS)

Developed is a model for studying the vibrations of a wind turbine tower subjected to random wind loadings. The tower is modeled as an elastic Euler-Bernoulli beam, viscously damped and fixed at the bottom. The concentrated mass of the turbine is located at the top of the tower where also the wind loading is applied as a step function. The partial differential equation of the model is managed by the method of separation of variables and along with the applied modal analysis produces an efficient numerical-analytic solution algorithm. Demonstrated is the ability for dissipating the vibrations through a properly designed controller. Numerical results are provided.

Genov, J.; Gilev, B.; Slavchev, Y.; Venkov, G.

2010-10-01

461

Causes of bat fatalities at wind turbines: Hypotheses and predictions  

USGS Publications Warehouse

Thousands of industrial-scale wind turbines are being built across the world each year to meet the growing demand for sustainable energy. Bats of certain species are dying at wind turbines in unprecedented numbers. Species of bats consistently affected by turbines tend to be those that rely on trees as roosts and most migrate long distances. Although considerable progress has been made in recent years toward better understanding the problem, the causes of bat fatalities at turbines remain unclear. In this synthesis, we review hypothesized causes of bat fatalities at turbines. Hypotheses of cause fall into 2 general categoriesproximate and ultimate. Proximate causes explain the direct means by which bats die at turbines and include collision with towers and rotating blades, and barotrauma. Ultimate causes explain why bats come close to turbines and include 3 general types: random collisions, coincidental collisions, and collisions that result from attraction of bats to turbines. The random collision hypothesis posits that interactions between bats and turbines are random events and that fatalities are representative of the bats present at a site. Coincidental hypotheses posit that certain aspects of bat distribution or behavior put them at risk of collision and include aggregation during migration and seasonal increases in flight activity associated with feeding or mating. A surprising number of attraction hypotheses suggest that bats might be attracted to turbines out of curiosity, misperception, or as potential feeding, roosting, flocking, and mating opportunities. Identifying, prioritizing, and testing hypothesized causes of bat collisions with wind turbines are vital steps toward developing practical solutions to the problem. ?? 2009 American Society of Mammalogists.

Cryan, P. M.; Barclay, R. M. R.

2009-01-01

462

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. 14 figs.

Muljadi, E.

1998-08-25

463

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)

1998-01-01

464

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

465

A Summary of the Fatigue Properties of Wind Turbine Materials  

SciTech Connect

Modern wind turbines are fatigue critical machines that are typically used to produce electrical power from the wind. The materials used to construct these machines are subjected to a unique loading spectrum that contains several orders of magnitude more cycles than other fatigue critical structures, e.g., an airplane. To facilitate fatigue designs, a large database of material properties has been generated over the past several years that is specialized to materials typically used in wind turbines. In this paper, I review these fatigue data. Major sections are devoted to the properties developed for wood, metals (primarily aluminum) and fiberglass. Special emphasis is placed on the fiberglass discussion because this material is current the material of choice for wind turbine blades. The paper focuses on the data developed in the U.S., but cites European references that provide important insights.

SUTHERLAND, HERBERT J.

1999-10-07

466

Application of Damage Detection Techniques Using Wind Turbine Modal Data  

SciTech Connect

As any structure ages, its structural characteristics will also change. The goal of this work was to determine if modal response data fkom a wind turbine could be used in the detection of damage. The input stimuli to the wind turbine were from traditional modal hammer input and natural wind excitation. The structural response data was acquired using accelerometers mounted on the rotor of a parked and undamaged horizontal-axis wind turbine. The bolts at the root of one of the three blades were then loosened to simulate a damaged blade. The structural response data of the rotor was again recorded. The undamaged and damage-simulated datasets were compared using existing darnage detection algorithms. Also, a novel algorithm for combining the results of different damage detection algorithms was utilized in the assessment of the data. This paper summarizes the code development and discusses some preliminary damage detection results.

Gross, E.; Rumsey, M.; Simmermacher, T.; Zadoks, R.I.

1998-12-17

467

Exploration of the vortex wake behind of wind turbine rotor  

NASA Astrophysics Data System (ADS)

The present paper describes a wind tunnel study of flow downstream a small horizontal axis wind turbine (HAWT). The experimental investigations were carried out with the use of particle image velocimetry (PIV). To obtain the flow field in the rotating frame of reference, the phase-locked technique was applied. Explorations were carried out in azimuth planes with different angles. The 3D velocity field was reconstituted by processing the images resulting from the explored azimuth planes. In addition to PIV investigations, hot-wire measurements were also carried out immediately behind the wind turbine rotor at different radial and axial distances. The obtained results are very useful to analyze wind turbine wake and to constitute a reference for CFD computation.

Massouh, F.; Dobrev, I.

2007-07-01

468

Large-eddy simulation of flow past wind turbine rotors  

NASA Astrophysics Data System (ADS)

Understanding the effects of atmospheric turbulence and terrain- specific flow phenomena on the aerodynamic performance of wind turbine rotors is critical perquisite for improving blade designs, developing effective flow control strategies and improving wind farm layouts. We develop a high resolution numerical method capable of carrying out large-eddy simulation of wind turbine flows in arbitrarily complex terrains. The method employs the curvilinear immersed boundary method coupled with overset grids and the governing equations can be solved both in the inertial and non- inertial frames. The method is validated by applying it to simulate the flow for the NREL phase VI wind turbine rotor for various operating points. In addition to LES, inviscid and unsteady RANS simulations are also carried out for all cases. The results from the different models are compared against each other and the experimental data and analyzed to provide turbulence statistics and the 3D flow structure in the rotor wake.

Borazjani, Iman; Sotiropoulos, Fotis

2010-11-01

469

76 FR 10328 - Grant of Authority for Subzone Status; Vestas Nacelles America, Inc. (Wind Turbine Nacelles, Hubs...  

Federal Register 2010, 2011, 2012, 2013

...Vestas Nacelles America, Inc. (Wind Turbine Nacelles, Hubs, Blades and Towers...special-purpose subzone at the wind turbine nacelle, hub, blade and tower manufacturing...manufacturing and warehousing of wind turbine nacelles, hubs, blades and towers...

2011-02-24

470

A new concept in horizontal axis wind turbine rotors  

NASA Astrophysics Data System (ADS)

A new concept for horizontal axis wind turbine rotors was developed at the University of Florida. The main feature of this concept is a 'segmented' blade design using uniform airfoil sections separated by thin aerodynamic fences. The fences allow the individual segments to have different orientations to provide desired twist and pitch. Several prototypes have been built and tested and a wind machine using this concept was the overall winner in the wind division of the ERA II SCORE competition in 1977.

Roan, V. P.

471

Methods and apparatus for cooling wind turbine generators  

DOEpatents

A wind turbine generator includes a stator having a core and a plurality of stator windings circumferentially spaced about a generator longitudinal axis. A rotor is rotatable about the generator longitudinal axis, and the rotor includes a plurality of magnetic elements coupled to the rotor and cooperating with the stator windings. The magnetic elements are configured to generate a magnetic field and the stator windings are configured to interact with the magnetic field to generate a voltage in the stator windings. A heat pipe assembly thermally engaging one of the stator and the rotor to dissipate heat generated in the stator or rotor.

Salamah, Samir A. (Niskayuna, NY); Gadre, Aniruddha Dattatraya (Rexford, NY); Garg, Jivtesh (Schenectady, NY); Bagepalli, Bharat Sampathkumaran (Niskayuna, NY); Jansen, Patrick Lee (Alplaus, NY); Carl, Jr., Ralph James (Clifton Park, NY)

2008-10-28

472

Southern California Wind Power Sensitivity to Turbine Hub Height, Rotor Radius and Rated Power  

NASA Astrophysics Data System (ADS)

Using hourly output from a 6km resolution mesoscale model and hypothetical wind turbine power curves, we quantify the sensitivity of wind power throughout Southern California to three key attributes of wind turbines: hub height, rotor radius and rated power. Changes in rotor diameter influence power in the variable speed region of the turbine power curve (wind speeds between the cut-in and rated speeds). For most Southern California regions, the bulk (>50%) of the wind speed distribution is contained between these two speeds. Rated power changes affect wind power for winds between the rated and cut-out speeds. Only offshore and mountain pass regions contain >40% of the wind speed distribution affected by rated power changes. Hub height changes can result in a wind distribution shift to the right, the magnitude of the shift dependent upon vertical wind shear. Thus, well-mixed boundary layer regions including offshore are less sensitive to hub height changes. All of these sensitivities fluctuate diurnally and seasonally with the amplitude dependent upon location. Using a turbine component cost scaling model, we compute total cost increments associated with each of the three turbine attribute changes. Among the three turbine characteristics explored, rotor radius provides the largest wind power change per dollar cost increment. Area averaged and maximum power change per dollar cost increment for rotor radius is 1.42 and 2.73 Watts/dollar, respectively. Although area averaged power change per dollar cost increment for rated power and hub height are similar (0.23 and 0.24 Watts/dollar), spatial variability of power sensitivity to rated power is greater. As much as 1 Watt/dollar cost increment in rated power is gained for offshore and mountain regions. Regions most insensitive to all three turbine characteristic changes include the coastal basin (Los Angeles to San Diego) and the southern San Joaquin Valley. Mountain passes are most sensitive to rated power and rotor radius changes. As expected, offshore regions are least sensitive to hub height changes because of reduced vertical wind shear relative to onshore.

Capps, S. B.; Hall, A. D.; Hughes, M. R.

2010-12-01