Science.gov

Sample records for grid connected integrated

  1. Power-based control with integral action for wind turbines connected to the grid

    NASA Astrophysics Data System (ADS)

    Peña, R. R.; Fernández, R. D.; Mantz, R. J.; Battaiotto, P. E.

    2015-10-01

    In this paper, a power shaping control with integral action is employed to control active and reactive powers of wind turbines connected to the grid. As it is well known, power shaping allows finding a Lyapunov function which ensures stability. In contrast to other passivity-based control theories, the power shaping controller design allows to use easily measurable variables, such as voltages and currents which simplify the physical interpretation and, therefore, the controller synthesis. The strategy proposed is evaluated in the context of severe operating conditions, such as abrupt changes in the wind speed and voltage drops.

  2. Integration of plug-in hybrid electric vehicles (PHEV) with grid connected residential photovoltaic energy systems

    NASA Astrophysics Data System (ADS)

    Nagarajan, Adarsh; Shireen, Wajiha

    2013-06-01

    This paper proposes an approach for integrating Plug-In Hybrid Electric Vehicles (PHEV) to an existing residential photovoltaic system, to control and optimize the power consumption of residential load. Control involves determining the source from which residential load will be catered, where as optimization of power flow reduces the stress on the grid. The system built to achieve the goal is a combination of the existing residential photovoltaic system, PHEV, Power Conditioning Unit (PCU), and a controller. The PCU involves two DC-DC Boost Converters and an inverter. This paper emphasizes on developing the controller logic and its implementation in order to accommodate the flexibility and benefits of the proposed integrated system. The proposed controller logic has been simulated using MATLAB SIMULINK and further implemented using Digital Signal Processor (DSP) microcontroller, TMS320F28035, from Texas Instruments

  3. Discrete-Time Integral Sliding Mode Control with Disturbances Compensation and Reduced Chattering for Pv Grid-Connected Inverter

    NASA Astrophysics Data System (ADS)

    Meo, Santolo; Sorrentino, Vincenzo

    2015-03-01

    In the paper a new discrete-time integral sliding mode control (DISMC) with disturbances compensation and reduced chattering for grid-connected inverter is proposed for active and reactive power regulation. Differently by many SMC proposed in literature that have a time-continuous formulation in spite have been implemented with digital processor, the proposed DISMC is fully formulated in discrete-time, taking into account the effects introduced by a microprocessor-based implementation. As will be demonstrated such approach consents to reduce the chattering about the sliding manifold within a boundary layer of O(T2) thickness instead of O(T) (being T the sampling period of the control algorithm). Moreover it introduces a correction of the control vector which eliminates the influence of modeling error and external disturbances improving stability and robustness of the controlled system. Constant converter switching frequency is achieved by using space vector modulation, which eases the design of the ac harmonic filter. In the paper, after a detailed formalization of the proposed control algorithm, several numerical and experimental results on a three-phase grid-connected inverter prototype are shown, proving the effectiveness of the control strategy.

  4. Smart Grid Integration Laboratory

    SciTech Connect

    Troxell, Wade

    2011-12-22

    The initial federal funding for the Colorado State University Smart Grid Integration Laboratory is through a Congressionally Directed Project (CDP), DE-OE0000070 Smart Grid Integration Laboratory. The original program requested in three one-year increments for staff acquisition, curriculum development, and instrumentation all which will benefit the Laboratory. This report focuses on the initial phase of staff acquisition which was directed and administered by DOE NETL/ West Virginia under Project Officer Tom George. Using this CDP funding, we have developed the leadership and intellectual capacity for the SGIC. This was accomplished by investing (hiring) a core team of Smart Grid Systems engineering faculty focused on education, research, and innovation of a secure and smart grid infrastructure. The Smart Grid Integration Laboratory will be housed with the separately funded Integrid Laboratory as part of CSU's overall Smart Grid Integration Center (SGIC). The period of performance of this grant was 10/1/2009 to 9/30/2011 which included one no cost extension due to time delays in faculty hiring. The Smart Grid Integration Laboratory's focus is to build foundations to help graduate and undergraduates acquire systems engineering knowledge; conduct innovative research; and team externally with grid smart organizations. Using the results of the separately funded Smart Grid Workforce Education Workshop (May 2009) sponsored by the City of Fort Collins, Northern Colorado Clean Energy Cluster, Colorado State University Continuing Education, Spirae, and Siemens has been used to guide the hiring of faculty, program curriculum and education plan. This project develops faculty leaders with the intellectual capacity to inspire its students to become leaders that substantially contribute to the development and maintenance of Smart Grid infrastructure through topics such as: (1) Distributed energy systems modeling and control; (2) Energy and power conversion; (3) Simulation of

  5. On automating domain connectivity for overset grids

    NASA Technical Reports Server (NTRS)

    Chiu, Ing-Tsau

    1994-01-01

    An alternative method for domain connectivity among systems of overset grids is presented. Reference uniform Cartesian systems of points are used to achieve highly efficient domain connectivity, and form the basis for a future fully automated system. The Cartesian systems are used to approximated body surfaces and to map the computational space of component grids. By exploiting the characteristics of Cartesian Systems, Chimera type hole-cutting and identification of donor elements for intergrid boundary points can be carried out very efficiently. The method is tested for a range of geometrically complex multiple-body overset grid systems.

  6. On automating domain connectivity for overset grids

    NASA Technical Reports Server (NTRS)

    Chiu, Ing-Tsau; Meakin, Robert L.

    1995-01-01

    An alternative method for domain connectivity among systems of overset grids is presented. Reference uniform Cartesian systems of points are used to achieve highly efficient domain connectivity, and form the basis for a future fully automated system. The Cartesian systems are used to approximate body surfaces and to map the computational space of component grids. By exploiting the characteristics of Cartesian systems, Chimera type hole-cutting and identification of donor elements for intergrid boundary points can be carried out very efficiently. The method is tested for a range of geometrically complex multiple-body overset grid systems. A dynamic hole expansion/contraction algorithm is also implemented to obtain optimum domain connectivity; however, it is tested only for geometry of generic shapes.

  7. High-efficiency grid-connected photovoltaic module integrated converter system with high-speed communication interfaces for small-scale distribution power generation

    SciTech Connect

    Choi, Woo-Young; Lai, Jih-Sheng

    2010-04-15

    This paper presents a high-efficiency grid-connected photovoltaic (PV) module integrated converter (MIC) system with reduced PV current variation. The proposed PV MIC system consists of a high-efficiency step-up DC-DC converter and a single-phase full-bridge DC-AC inverter. An active-clamping flyback converter with a voltage-doubler rectifier is proposed for the step-up DC-DC converter. The proposed step-up DC-DC converter reduces the switching losses by eliminating the reverse-recovery current of the output rectifying diodes. To reduce the PV current variation introduced by the grid-connected inverter, a PV current variation reduction method is also suggested. The suggested PV current variation reduction method reduces the PV current variation without any additional components. Moreover, for centralized power control of distributed PV MIC systems, a PV power control scheme with both a central control level and a local control level is presented. The central PV power control level controls the whole power production by sending out reference power signals to each individual PV MIC system. The proposed step-up DC-DC converter achieves a high-efficiency of 97.5% at 260 W output power to generate the DC-link voltage of 350 V from the PV voltage of 36.1 V. The PV MIC system including the DC-DC converter and the DC-AC inverter achieves a high-efficiency of 95% with the PV current ripple less than 3% variation of the rated PV current. (author)

  8. Solar energy grid integration systems "SEGIS"

    SciTech Connect

    None, None

    2007-10-01

    The inevitable transformation of the electrical grid to a more distributed generation configuration requires solar system capabilities well beyond simple net-metered, grid-connected approaches. Time-of-use and peak-demand rate structures will require more sophisticated systems designs that integrate energy management and/or energy storage into the system architecture. Controlling power flow into and from the utility grid will be required to ensure grid reliability and power quality. Alternative protection strategies will also be required to accommodate large numbers of distributed energy sources. This document provides an overview of the R&D needs and describes some pathways to promising solutions. The solutions will, in many cases, require R&D of new components, innovative inverter/controllers, energy management systems, innovative energy storage and a suite of advanced control algorithms, technical methodologies, protocols and the associated communications. It is expected that these solutions will help to push the “advanced integrated system” and “smart grid” evolutionary processes forward in a faster but focused manner.

  9. Current control loop of 3-phase grid-connected inverter

    NASA Astrophysics Data System (ADS)

    Jabbar, A. F.; Mansor, M.

    2013-06-01

    This paper presents a comparative study of current control loop in 3-phase inverter which is used to control the active and reactive output power. Generally, current control loop, power control loop and phase lock-loop are the conventional parameters that can be found in an inverter system controlled by the conventional linear control type, for instance proportional (P), integral (I) and derivative (D). If the grid remains stable throughout the day, PID control can be use. However variation of magnitude, frequency, voltage dips, transient, and other related power quality issues occur in a 3-phase grid often affects the control loop. This paper aims to provide an overall review on the available current control techniques used in grid connected system.

  10. The CMS integration grid testbed

    SciTech Connect

    Graham, Gregory E.

    2004-08-26

    The CMS Integration Grid Testbed (IGT) comprises USCMS Tier-1 and Tier-2 hardware at the following sites: the California Institute of Technology, Fermi National Accelerator Laboratory, the University of California at San Diego, and the University of Florida at Gainesville. The IGT runs jobs using the Globus Toolkit with a DAGMan and Condor-G front end. The virtual organization (VO) is managed using VO management scripts from the European Data Grid (EDG). Gridwide monitoring is accomplished using local tools such as Ganglia interfaced into the Globus Metadata Directory Service (MDS) and the agent based Mona Lisa. Domain specific software is packaged and installed using the Distribution After Release (DAR) tool of CMS, while middleware under the auspices of the Virtual Data Toolkit (VDT) is distributed using Pacman. During a continuous two month span in Fall of 2002, over 1 million official CMS GEANT based Monte Carlo events were generated and returned to CERN for analysis while being demonstrated at SC2002. In this paper, we describe the process that led to one of the world's first continuously available, functioning grids.

  11. Grid Integration Studies: Data Requirements, Greening the Grid

    SciTech Connect

    Katz, Jessica

    2015-06-01

    A grid integration study is an analytical framework used to evaluate a power system with high penetration levels of variable renewable energy (VRE). A grid integration study simulates the operation of the power system under different VRE scenarios, identifying reliability constraints and evaluating the cost of actions to alleviate those constraints. These VRE scenarios establish where, how much, and over what timeframe to build generation and transmission capacity, ideally capturing the spatial diversity benefits of wind and solar resources. The results help build confidence among policymakers, system operators, and investors to move forward with plans to increase the amount of VRE on the grid.

  12. Development of a low-cost integrated 20-kW ac solar tracking sub- array for grid-connected PV power system applications. Phase 1, Annual technical report, 11 July 1995--31 July 1996

    SciTech Connect

    Stern, M.; West, R.; Fourer, G.; Whalen, W.; Van Loo, M.; Duran, G.

    1997-06-01

    The overall goal of this effort is to reduce the installed cost of utility scale grid connected photovoltaic power systems. The focus of the effort is on ``BOS`` (Balance-Of-System) component manufacturing technology, which essentially involves all PV power system engineering, manufacturing, assembly and construction tasks from the receipt of a PV module to the deliver of grid connected electricity.

  13. Task 4 completion report for 40 Kilowatt grid connected modification contract

    NASA Technical Reports Server (NTRS)

    Vogt, J. H.

    1983-01-01

    Startup, operation in grid connect mode, shutdown from grid connects, operation in isolated mode, shutdown from isolated mode, steady state operation, mode transfers, and voltage disconnects are addressed.

  14. High-performance inverters for grid-connected PV applications

    SciTech Connect

    Heide, F.J. ter; Wanner, J.

    1994-12-31

    In a few years time Mastervolt has become one of the leading European manufacturers of stand-alone inverters for marine and mobile applications. The application of photovoltaics in this area is well on its way. Based on this experience the development of grid-connected inverters evolved naturally within the context of the effort for development of grid-connected photovoltaic systems in the Netherlands. Technical description and applications are given for the Sunmaster 1800 and 300.

  15. Scaling Up Renewable Energy Generation: Aligning Targets and Incentives with Grid Integration Considerations, Greening The Grid

    SciTech Connect

    Katz, Jessica; Cochran, Jaquelin

    2015-05-27

    Greening the Grid provides technical assistance to energy system planners, regulators, and grid operators to overcome challenges associated with integrating variable renewable energy into the grid. This document, part of a Greening the Grid toolkit, provides power system planners with tips to help secure and sustain investment in new renewable energy generation by aligning renewable energy policy targets and incentives with grid integration considerations.

  16. Domain connectivity among systems of overset grids

    NASA Technical Reports Server (NTRS)

    Meakin, Robert L.

    1993-01-01

    This progress report describes research performed to achieve algorithmic improvements in the use of overset grids for the computation of unsteady flowfields about geometrically complex and moving component configurations. A hole-map computational method is detailed that reduces computational demand and corresponding demand on human resources. Results indicate that the method is both efficient and flexible for use in complex simulation cases. Tests were performed on shuttle orbiter/external tank, wing/store, and V-22 tilt-rotor configurations. The number of simulated points and the corresponding time on a SGI 4D-210 workstation are presented.

  17. Correlations and Functional Connections in a Population of Grid Cells

    PubMed Central

    Roudi, Yasser

    2015-01-01

    We study the statistics of spike trains of simultaneously recorded grid cells in freely behaving rats. We evaluate pairwise correlations between these cells and, using a maximum entropy kinetic pairwise model (kinetic Ising model), study their functional connectivity. Even when we account for the covariations in firing rates due to overlapping fields, both the pairwise correlations and functional connections decay as a function of the shortest distance between the vertices of the spatial firing pattern of pairs of grid cells, i.e. their phase difference. They take positive values between cells with nearby phases and approach zero or negative values for larger phase differences. We find similar results also when, in addition to correlations due to overlapping fields, we account for correlations due to theta oscillations and head directional inputs. The inferred connections between neurons in the same module and those from different modules can be both negative and positive, with a mean close to zero, but with the strongest inferred connections found between cells of the same module. Taken together, our results suggest that grid cells in the same module do indeed form a local network of interconnected neurons with a functional connectivity that supports a role for attractor dynamics in the generation of grid pattern. PMID:25714908

  18. TeraGrid's integrated information service.

    SciTech Connect

    Liming, L.; Navarro, J.-P.; Blau, E.; Brechin, J.; Catlett, C.; Dahan, M.; Diehl, D.; Dooley, R.; Dwyer, M.; Ericson, K.; Foster, I.; Hanna, E.; Hart, D. L.; Jordan, C.; Light, R.; Martin, S.; McGee, J.; Pearlman, L.; Reilly, J.; Scavo, T.; Shapiro, M.; Smallen, S.; Smith, W.; Wilkins-Diehr, N.

    2009-01-01

    The NSF TeraGrid project has designed and constructed a federated integrated information service (IIS) to serve its capability publishing and discovery needs. This service has also proven helpful in automating TeraGrid's operational activities. We describe the requirements that motivated this work; IIS's system architecture, information architecture, and information content; processes that IIS currently supports; and how various layers of the system architecture are being used. We also review motivating use cases that have not yet been satisfied by IIS and outline approaches for future work.

  19. Role of Smarter Grids in Variable Renewable Resource Integration (Presentation)

    SciTech Connect

    Miller, M.

    2012-07-01

    This presentation discusses the role of smarter grids in variable renewable resource integration and references material from a forthcoming ISGAN issue paper: Smart Grid Contributions to Variable Renewable Resource Integration, co-written by the presenter and currently in review.

  20. Solar cells having integral collector grids

    NASA Technical Reports Server (NTRS)

    Evans, J. C., Jr. (Inventor)

    1978-01-01

    A heterojunction or Schottky barrier photovoltaic device is described, comprising a conductive base metal layer. A back surface field region was formed at the interface between the device and the base metal layer, a transparent, conductive mixed metal oxide layer in integral contact with the n-type layer of the heterojunction or Schottky barrier device. A metal alloy grid network was included. An insulating layer prevented electrical contact between the conductive metal base layer and the transparent, conductive metal oxide layer.

  1. Four Federal Grid-Connected Photovoltaic Systems: Powering Our Nation's Capital with Solar

    SciTech Connect

    Plympton, P.; Kappaz, P.; Kroposki, B.; Stafford, B.; Thornton, J.

    2001-04-16

    One of the fastest growing markets for photovoltaics (PV) is the urban sector. Municipal planners have discovered that PV systems operate favorably in their urban areas, and can be aesthetically integrated into the urban landscape. The federal government has a long history of using PV in a variety of applications, but until recently few applications have been in urban environments. During the last five years, four grid-connected PV systems have been installed on federally owned or federally leased facilities in the Washington, D.C. area: (1) Earth Day Park, (2) U.S. Department of Energy Headquarters, (3) the Pentagon, and (4) Federal Energy Regulatory Commission Headquarters. This paper reviews these four urban, grid-connected systems-particularly the issues of siting, permitting, and grid interconnection.

  2. Integrating Renewable Electricity on the Grid

    NASA Astrophysics Data System (ADS)

    Crabtree, George; Misewich, Jim; Ambrosio, Ron; Clay, Kathryn; DeMartini, Paul; James, Revis; Lauby, Mark; Mohta, Vivek; Moura, John; Sauer, Peter; Slakey, Francis; Lieberman, Jodi; Tai, Humayun

    2011-11-01

    patchwork of conventional transmission lines would create an interstate highway system for electricity that moves large amounts of renewable electric power efficiently over long distances from source to load. Research and development is needed to identify the technical challenges associated with DC superconducting transmission and how it can be most effectively deployed. The challenge of variability can be met (i) by switching conventional generation capacity in or out in response to sophisticated forecasts of weather and power generation, (ii) by large scale energy storage in heat, pumped hydroelectric, compressed air or stationary batteries designed for the grid, or (iii) by national balancing of regional generation deficits and excesses using long distance transmission. Each of these solutions to variability has merit and each requires significant research and development to understand its capacity, performance, cost and effectiveness. The challenge of variability is likely to be met by a combination of these three solutions; the interactions among them and the appropriate mix needs to be explored. The long distances from renewable sources to demand centers span many of the grid's physical, ownership and regulatory boundaries. This introduces a new feature to grid structure and operation: national and regional coordination. The grid is historically a patchwork of local generation resources and load centers that has been built, operated and regulated to meet local needs. Although it is capable of sharing power across moderate distances, the arrangements for doing so are cumbersome and inefficient. The advent of renewable electricity with its enormous potential and inherent regional and national character presents an opportunity to examine the local structure of the grid and establish coordinating principles that will not only enable effective renewable integration but also simplify and codify the grid's increasingly regional and national character.

  3. Integrated geometry and grid generation system for complex configurations

    NASA Technical Reports Server (NTRS)

    Akdag, Vedat; Wulf, Armin

    1992-01-01

    A grid generation system was developed that enables grid generation for complex configurations. The system called ICEM/CFD is described and its role in computational fluid dynamics (CFD) applications is presented. The capabilities of the system include full computer aided design (CAD), grid generation on the actual CAD geometry definition using robust surface projection algorithms, interfacing easily with known CAD packages through common file formats for geometry transfer, grid quality evaluation of the volume grid, coupling boundary condition set-up for block faces with grid topology generation, multi-block grid generation with or without point continuity and block to block interface requirement, and generating grid files directly compatible with known flow solvers. The interactive and integrated approach to the problem of computational grid generation not only substantially reduces manpower time but also increases the flexibility of later grid modifications and enhancements which is required in an environment where CFD is integrated into a product design cycle.

  4. NWTC Transmission and Grid Integration (Revised) (Fact Sheet)

    SciTech Connect

    Not Available

    2010-04-01

    The rapid growth of alternative power sources, especially wind power, is creating challenges that affect the existing electric grid. To keep up with this rapid growth, researchers in the Transmission and Grid Integration Group provide scientific, engineering, and analytical expertise to help advance alternative energy and accelerate its integration into the nation's electrical grid. For example, we evaluate U.S. wind energy resources and collect and analyze data about the impact of wind development on the electrical grid. Researchers in the Transmission and Grid Integration Group offer assistance to utility industry partners in the following integration areas.

  5. Metrics for Assessment of Smart Grid Data Integrity Attacks

    SciTech Connect

    Annarita Giani; Miles McQueen; Russell Bent; Kameshwar Poolla; Mark Hinrichs

    2012-07-01

    There is an emerging consensus that the nation’s electricity grid is vulnerable to cyber attacks. This vulnerability arises from the increasing reliance on using remote measurements, transmitting them over legacy data networks to system operators who make critical decisions based on available data. Data integrity attacks are a class of cyber attacks that involve a compromise of information that is processed by the grid operator. This information can include meter readings of injected power at remote generators, power flows on transmission lines, and relay states. These data integrity attacks have consequences only when the system operator responds to compromised data by redispatching generation under normal or contingency protocols. These consequences include (a) financial losses from sub-optimal economic dispatch to service loads, (b) robustness/resiliency losses from placing the grid at operating points that are at greater risk from contingencies, and (c) systemic losses resulting from cascading failures induced by poor operational choices. This paper is focused on understanding the connections between grid operational procedures and cyber attacks. We first offer two examples to illustrate how data integrity attacks can cause economic and physical damage by misleading operators into taking inappropriate decisions. We then focus on unobservable data integrity attacks involving power meter data. These are coordinated attacks where the compromised data are consistent with the physics of power flow, and are therefore passed by any bad data detection algorithm. We develop metrics to assess the economic impact of these attacks under re-dispatch decisions using optimal power flow methods. These metrics can be use to prioritize the adoption of appropriate countermeasures including PMU placement, encryption, hardware upgrades, and advance attack detection algorithms.

  6. Simulation for Grid Connected Wind Turbines with Fluctuating

    NASA Astrophysics Data System (ADS)

    Ye, Ying; Fu, Yang; Wei, Shurong

    This paper establishes the whole dynamic model of wind turbine generator system which contains the wind speed model and DFIG wind turbines model .A simulation sample based on the mathematical models is built by using MATLAB in this paper. Research are did on the performance characteristics of doubly-fed wind generators (DFIG) which connected to power grid with three-phase ground fault and the disturbance by gust and mixed wind. The capacity of the wind farm is 9MW which consists of doubly-fed wind generators (DFIG). Simulation results demonstrate that the three-phase ground fault occurs on grid side runs less affected on the stability of doubly-fed wind generators. However, as a power source, fluctuations of the wind speed will run a large impact on stability of double-fed wind generators. The results also show that if the two disturbances occur in the meantime, the situation will be very serious.

  7. The development and performance of smud grid-connected photovoltaic projects

    SciTech Connect

    Osborn, D.E.; Collier, D.E.

    1995-11-01

    The utility grid-connected market has been identified as a key market to be developed to accelerate the commercialization of photovoltaics. The Sacramento Municipal Utility District (SMUD) has completed the first two years of a continuing commercialization effort based on two years of a continuing commercialization effort based on the sustained, orderly development of the grid-connected, utility PV market. This program is aimed at developing the experience needed to successfully integrate PV as distributed generation into the utility system and to stimulate the collaborative processes needed to accelerate the cost reductions necessary for PV to be cost-effective in these applications by the year 2000. In the first two years, SMUD has installed over 240 residential and commercial building, grid-connected, rooftop, {open_quotes}PV Pioneer{close_quotes} systems totaling over 1MW of capacity and four substation sited, grid-support PV systems totaling 600 kW bringing the SMUD distributed PV power systems to over 3.7 MW. The 1995 SMUD PV Program will add another approximately 800 kW of PV systems to the District`s distributed PV power system. SMUD also established a partnership with its customers through the PV Pioneer {open_quotes}green pricing{close_quotes} program to advance PV commercialization.

  8. Residential photovoltaic power conditioning technology for grid connected applications

    NASA Technical Reports Server (NTRS)

    Key, T. S.; Klein, J. W.

    1982-01-01

    Major advances in photovoltaic (PV) Power Conditioning (PC) with respect to performance and low-cost potential have been made. Solutions have been obtained to interface and control problems related to adapting available inverter designs to the grid-connected, residential photovoltaic experiments. A description is presented to contributing research and development activities. Attention is given to aspects of residential systems experience, conceptual design studies, questions of optimum topology development, and promising advanced designs for residential PV provided by development efforts of the private sector.

  9. Subsystem engineering and development of grid-connected photovoltaic systems

    SciTech Connect

    Burgess, E.L.; Post, H.N.; Key, T.S.

    1982-01-01

    The experience gained in fielding residential and intermediate sized photovoltaic application experiments is summarized. This experience is used to guide the engineering and development of array and power conditioning subsystems for grid-connected photovoltaic systems. A major consideration in this development effort is cost. Through innovative engineering, using a modular building block approach for the array subsystem, it is now possible to construct array fields, in moderate quantities, for about $52/m/sup 2/ excluding the photovoltaic modules. Similarly, results of power conditioning subsystem development indicate a projected cost of about $0.25/W/sub p/ for advanced units with conversion efficiencies in excess of 90%.

  10. GRID integration of oceanographic remote instrumentation

    NASA Astrophysics Data System (ADS)

    Salon, S.; Bolzon, G.; Mauri, E.; Poulain, P.-M.

    2009-04-01

    The observations provided by oceanographic remote instruments are essential for the purposes of the operational oceanography, nowadays a constantly growing and powerful tool to monitor, analyze and predict the state of the marine resources as well as the sustainable development of coastal areas [1]. Near real time (NRT) observations at the sea surface and in the water column, e.g., temperature and salinity (T/S) profiles, are of central importance for the operational forecasting system in the Mediterranean Sea. The management of the network of floats deployed in the Mediterranean Sea and handled by the MedArgo Regional Argo Centre at OGS [2][3] is a complex task that may be greatly supported by the fast developing ICT infrastructures. Such workflow includes the communication system, the data downloading and treatment, the post-processing and the visualization of the information gathered by the observations. GRID technology may greatly help in providing a remote control of the entire flow of information associated with the observational instruments, from the raw data measured by the sensor at sea (i.e. temperature, salinity, current velocity) to the data-processing software running on the researcher's laptop. In particular, interactive applications of the GRID technology could support the management of the complex workflow related to the instrument interconnections (i.e. buoys, floats, autonomous vehicles), to the eventual technical problems bound to appear intermittently and the subsequent NRT corrections and/or adjustments of the sensors. Moreover, the communication to operative structures such as the Civil Protection, Coast Guards or local/regional administrations represents a composite multi-task process that involves different actors and that could be successfully integrated in a GRID environment. We will present the activity done so far and planned in the framework of the DORII EU-FP7 project [4] concerning the GRID integration of the MedArgo floats managed by

  11. Connecting Your Solar Electric System to the Utility Grid: Better Buildings Series Solar Electric Fact Sheet

    SciTech Connect

    Not Available

    2002-07-01

    In recent years, the number of solar-powered homes connected to the local utility grid has increased dramatically. These''grid-connected'' buildings have solar electric panels or''modules'' that provide some or even most of their power, while still being connected to the local utility. This fact sheet provides information on connecting your solar electric system to the utility grid, including information on net metering.

  12. Comparative Study of Standards for Grid-Connected Wind Power Plant in China and the U.S.

    SciTech Connect

    Gao, Wenzhong; Tian, Tian; Muljadi, Eduard; Zhang, Yincheng; Miller, Mackay; Wang, Weisheng; Wang, Jing

    2015-10-06

    The rapid deployment of wind power has made grid integration and operational issues focal points in industry discussions and research. Compliance with grid connection standards for wind power plants (WPP) is crucial to ensuring the safe and stable operation of the electric power grid. The standards for grid-connected WPPs in China and the United States are compared in this paper to facilitate further improvements to the standards and enhance the development of wind power equipment. Detailed analyses in power quality, low-voltage ride-through capability, active power control, reactive power control, voltage control, and wind power forecasting are provided to enhance the understanding of grid codes in the two largest markets of wind power.

  13. 30 CFR 56.12023 - Guarding electrical connections and resistor grids.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... grids. 56.12023 Section 56.12023 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF... MINES Electricity § 56.12023 Guarding electrical connections and resistor grids. Electrical connections and resistor grids that are difficult or impractical to insulate shall be guarded, unless...

  14. 30 CFR 57.12023 - Guarding electrical connections and resistor grids.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Guarding electrical connections and resistor grids. 57.12023 Section 57.12023 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF... grids. Electrical connections and resistor grids that are difficult or impractical to insulate shall...

  15. Balancing Area Coordination: Efficiently Integrating Renewable Energy Into the Grid, Greening the Grid

    SciTech Connect

    Katz, Jessica; Denholm, Paul; Cochran, Jaquelin

    2015-06-01

    Greening the Grid provides technical assistance to energy system planners, regulators, and grid operators to overcome challenges associated with integrating variable renewable energy into the grid. Coordinating balancing area operation can promote more cost and resource efficient integration of variable renewable energy, such as wind and solar, into power systems. This efficiency is achieved by sharing or coordinating balancing resources and operating reserves across larger geographic boundaries.

  16. Mapping unstructured grid problems to the connection machine

    NASA Technical Reports Server (NTRS)

    Hammond, Steven W.; Schreiber, Robert

    1990-01-01

    We present a highly parallel graph mapping technique that enables one to solve unstructured grid problems on massively parallel computers. Many implicit and explicit methods for solving discretizated partial differential equations require each point in the discretization to exchange data with its neighboring points every time step or iteration. The time spent communicating can limit the high performance promised by massively parallel computing. To eliminate this bottleneck, we map the graph of the irregular problem to the graph representing the interconnection topology of the computer such that the sum of the distances that the messages travel is minimized. We show that, in comparison to a naive assignment of processors, our heuristic mapping algorithm significantly reduces the communication time on the Connection Machine, CM-2.

  17. Performance model for grid-connected photovoltaic inverters.

    SciTech Connect

    Boyson, William Earl; Galbraith, Gary M.; King, David L.; Gonzalez, Sigifredo

    2007-09-01

    This document provides an empirically based performance model for grid-connected photovoltaic inverters used for system performance (energy) modeling and for continuous monitoring of inverter performance during system operation. The versatility and accuracy of the model were validated for a variety of both residential and commercial size inverters. Default parameters for the model can be obtained from manufacturers specification sheets, and the accuracy of the model can be further refined using measurements from either well-instrumented field measurements in operational systems or using detailed measurements from a recognized testing laboratory. An initial database of inverter performance parameters was developed based on measurements conducted at Sandia National Laboratories and at laboratories supporting the solar programs of the California Energy Commission.

  18. RETHINKING THE FUTURE GRID: INTEGRATED NUCLEAR-RENEWABLE ENERGY SYSTEMS

    SciTech Connect

    S.M. Bragg-Sitton; R. Boardman

    2014-12-01

    integrate two or more energy resources to generate two or more products, one of which must be an energy commodity, such as electricity or transportation fuel. Subsystems would be integrated ‘‘behind’’ the electrical transmission bus and would be comprised of two or more energy conversion subsystems that have traditionally been separate or isolated. Energy flows would be dynamically apportioned as necessary to meet grid demand via a single, highly responsive connection to the grid that provides dispatchable electricity while capital-intensive generation assets operate at full capacity. Candidate region-specific hybrid energy systems selected for further study and figures of merit that will be used to assess system performance will be presented.

  19. Optimal reactive power control of grid connected photovoltaic resources

    NASA Astrophysics Data System (ADS)

    Trimble, Joshua Ryan

    As more photovoltaic distributed generation resources are installed on distribution power systems, selective control of the inverters connecting the DC power sources presents the opportunity to supply both real and reactive power at the point of common coupling. This thesis presents a simulated distribution system with individually controlled PV resources with the objective of minimizing total system losses while operating at the maximum power point and below the simulated rating of the associated inverters. The control strategy assumes the characteristics of the distribution system are known and solves for the optimal power flow operating point. The ability of each PV source to provide real and reactive power varies instantaneously as irradiance changes, so the operating point for each resource must be constantly recalculated and adjusted. The assumption of known system paramaters can be justified in a SmartGrid context, and a solution based on overall system power flow should be considered as a benchmark for any other state estimation or local control approaches.

  20. Multipurpose Power Converter for Non-Grid-Connected Microsystems

    NASA Astrophysics Data System (ADS)

    Vovos, Panagis N.; Georgakas, Konstantinos G.

    2015-04-01

    The aim of this paper is to present a multipurpose converter, appropriate for non-grid-connected microsystems, which are prone to harmonic distortion. The converter suppresses harmonics by injecting mirror harmonics in the modulation stage. An important property is that it continuously monitors and significantly reduces the harmonic content without the use of active or passive low-frequency filters. This is under constant switching frequency, no matter if the harmonics are mainly created by the source, the loads or even its own operation. The converter is regulating output voltage using typical fuzzy control. The two types of control (harmonic and voltage) do not seem to affect each other during operation. Furthermore, it can supply either dc or ac loads from a dc source. The versatility of the converter is a useful property for remote or mobile micropower systems, where neither sources nor loads are of a single type. The converter has been tested successfully for a combination of harmonic-injecting electric appliances and various load step changes.

  1. Aggregation server for grid-integrated vehicles

    SciTech Connect

    Kempton, Willett

    2015-05-26

    Methods, systems, and apparatus for aggregating electric power flow between an electric grid and electric vehicles are disclosed. An apparatus for aggregating power flow may include a memory and a processor coupled to the memory to receive electric vehicle equipment (EVE) attributes from a plurality of EVEs, aggregate EVE attributes, predict total available capacity based on the EVE attributes, and dispatch at least a portion of the total available capacity to the grid. Power flow may be aggregated by receiving EVE operational parameters from each EVE, aggregating the received EVE operational parameters, predicting total available capacity based on the aggregated EVE operational parameters, and dispatching at least a portion of the total available capacity to the grid.

  2. Market-Based Indian Grid Integration Study Options: Preprint

    SciTech Connect

    Stoltenberg, B.; Clark, K.; Negi, S. K.

    2012-03-01

    The Indian state of Gujarat is forecasting solar and wind generation expansion from 16% to 32% of installed generation capacity by 2015. Some states in India are already experiencing heavy wind power curtailment. Understanding how to integrate variable generation (VG) into the grid is of great interest to local transmission companies and India's Ministry of New and Renewable Energy. This paper describes the nature of a market-based integration study and how this approach, while new to Indian grid operation and planning, is necessary to understand how to operate and expand the grid to best accommodate the expansion of VG. Second, it discusses options in defining a study's scope, such as data granularity, generation modeling, and geographic scope. The paper also explores how Gujarat's method of grid operation and current system reliability will affect how an integration study can be performed.

  3. Interim Test Procedures for Evaluating Electrical Performance and Grid Integration of Vehicle-to-Grid Applications

    SciTech Connect

    Chakraborty, S.; Kramer, W.; Kroposki, B.; Martin, G.; McNutt, P.; Kuss, M.; Markel, T.; Hoke, A.

    2011-06-01

    The objective of this report is to provide a test plan for V2G testing. The test plan is designed to test and evaluate the vehicle's power electronics capability to provide power to the grid, and to evaluate the vehicle's ability to connect and disconnect from the utility according to a subset of the IEEE Std. 1547 tests.

  4. Physiological integration of connected balsam poplar ramets.

    PubMed

    Adonsou, Kokouvi Emmanuel; DesRochers, Annie; Tremblay, Francine

    2016-07-01

    Clonal integration between ramets can be an ecological advantage of clonal plant species in environments where resources are patchily distributed. We investigated physiological integration among Populus balsamifera L. ramets under drought stress in order to demonstrate water sharing between connected ramets. Pairs of connected ramets were grown in separate pots in the greenhouse where half of ramets had the parental root connection severed and half were left intact. Drought stress was applied to one ramet, and growth, specific leaf area (SLA), net photosynthesis, stomatal conductance, leaf water potential and carbon isotopic composition (δ(13)C) were measured after an 8-week growing period. Droughted ramets connected to watered ramets were able to maintain high gas exchange activity and water potential, similar to watered ramets. Leaf water potential and SLA results showed that the root connection was more beneficial for proximal compared with distal ramets. The parental root connection also allowed droughted ramets to discriminate more against (13)C compared with severed ramets. In conclusion, this study shows compelling evidence of physiological integration of connected P. balsamifera ramets through water sharing. PMID:26843209

  5. School Finance and Technology: A Case Study Using Grid and Group Theory to Explore the Connections

    ERIC Educational Resources Information Center

    Case, Stephoni; Harris, Edward L.

    2014-01-01

    Using grid and group theory (Douglas 1982, 2011), the study described in this article examined the intersections of technology and school finance in four schools located in districts differing in size, wealth, and commitment to technology integration. In grid and group theory, grid refers to the degree to which policies and role prescriptions…

  6. Integrating Variable Renewable Energy into the Grid: Key Issues, Greening the Grid

    SciTech Connect

    Katz, Jessica; Cochran, Jaquelin

    2015-05-01

    To foster sustainable, low-emission development, many countries are establishing ambitious renewable energy targets for their electricity supply. Because solar and wind tend to be more variable and uncertain than conventional sources, meeting these targets will involve changes to power system planning and operations. Grid integration is the practice of developing efficient ways to deliver variable renewable energy (VRE) to the grid. Good integration methods maximize the cost-effectiveness of incorporating VRE into the power system while maintaining or increasing system stability and reliability. When considering grid integration, policy makers, regulators, and system operators consider a variety of issues, which can be organized into four broad topics: New Renewable Energy Generation, New Transmission, Increased System Flexibility, Planning for a High RE Future.

  7. Role of Smart Grids in Integrating Renewable Energy

    SciTech Connect

    Speer, B.; Miller, M.; Schaffer, W.; Gueran, L.; Reuter, A.; Jang, B.; Widegren, K.

    2015-05-27

    This report was prepared for the International Smart Grid Action Network (ISGAN), which periodically publishes briefs and discussion papers on key topics of smart grid development globally. The topic of this report was selected by a multilateral group of national experts participating in ISGAN Annex 4, a working group that aims to produce synthesis insights for decision makers. This report is an update of a 2012 ISGAN Annex 4 report entitled “Smart Grid Contributions to Variable Renewable Resource Integration.” That report and other past publications of ISGAN Annexes can be found at www.iea-isgan.org and at www.cleanenergysolutions.org.

  8. API connection modification to improve pressure integrity

    SciTech Connect

    Chelette, K.D.; Bollfrass, C.A.

    1983-01-01

    The pressure sealing integrity of API Round Thread and Buttress pipe connections is established by variations in the nominal design conditions that result from the specified dimensional tolerances. Several coupling modifications and procedures are presented herein to improve the sealing integrity of API connections. This improved coupling design uses multiple thread tapers to increase internal pressure ratings by insuring the location of the sealing point, insure tensile performance by excluding pressure from the thread region, and developing proper thread interference by controlling the final assembly position.

  9. Economics of grid-connected small wind turbines in the domestic market

    SciTech Connect

    Forsyth, T.; Tu, P.; Gilbert, J.

    2000-06-29

    Exploitation of certain niche markets for small wind turbines is one strategy that could help speed the commercialization of grid-connected small turbines. The authors review the world's turbine manufacturers, the utility grid-connected applications and selected niche markets for grid-connected small wind systems (0.1 to 100 kilowatts). Wind turbine installation and purchase are handled under three different payment scenarios: paid in full up front, paid through a second mortgage, or paid as part of a first mortgage. The authors used a simple payback method to compare these scenarios and analyze the costs and energy produced for three different U.S. small wind turbines. When there is a buy-down program for the small wind turbine combined with other financial factors such as net metering, tax exemptions, and tax credits, a strong market incentive is created for the use of grid-connected small wind turbines.

  10. Modeling and Control of VSC Based DC Connection for Active Stall Wind Farms to Grid

    NASA Astrophysics Data System (ADS)

    Iov, Florin; Sørensen, Poul; Hansen, Anca Daniela; Blaabjerg, Frede

    Currently, there is an increasing trend to connect large MW wind farms to the transmission system. Therefore the power system becomes more vulnerable and dependent on the wind energy production. At the same time requirements that focus on the influence of the farms on the grid stability and power quality, and on the control capabilities of wind farms have already been established. The main trends of modern wind turbines/farms are clearly the variable speed operation and a grid connection through a power electronic interface, especially using doubly-fed induction generators. Using power electronics the control capabilities of these wind turbines/farms are extended and thus the grid requirements are fulfilled. However, the traditional squirrel-cage generators based wind turbines/wind farms directly connected to the grid does not have such control capabilities. They produce maximum possible power in continuous operation and are becoming disconnected in the case of a grid fault. Moreover, these wind turbines/farms cannot regulate their production and contribute to power system stability. A DC transmission system for connection of the active stall wind farms to the grid can be a solution to these problems. Such a system has special regulating properties e.g. decoupled control of active and reactive power, continuous AC voltage regulation, variable frequency control, black-start capability, etc. This paper focuses on the modeling of such systems and proposes a control method of a voltage source converter based DC transmission system for connecting active stall wind farms to the grid.

  11. Message passing for integrating and assessing renewable generation in a redundant power grid

    SciTech Connect

    Zdeborova, Lenka; Backhaus, Scott; Chertkov, Michael

    2009-01-01

    A simplified model of a redundant power grid is used to study integration of fluctuating renewable generation. The grid consists of large number of generator and consumer nodes. The net power consumption is determined by the difference between the gross consumption and the level of renewable generation. The gross consumption is drawn from a narrow distribution representing the predictability of aggregated loads, and we consider two different distributions representing wind and solar resources. Each generator is connected to D consumers, and redundancy is built in by connecting R {le} D of these consumers to other generators. The lines are switchable so that at any instance each consumer is connected to a single generator. We explore the capacity of the renewable generation by determining the level of 'firm' generation capacity that can be displaced for different levels of redundancy R. We also develop message-passing control algorithm for finding switch sellings where no generator is overloaded.

  12. GPCALMA: A Tool For Mammography With A GRID-Connected Distributed Database

    NASA Astrophysics Data System (ADS)

    Bottigli, U.; Cerello, P.; Cheran, S.; Delogu, P.; Fantacci, M. E.; Fauci, F.; Golosio, B.; Lauria, A.; Lopez Torres, E.; Magro, R.; Masala, G. L.; Oliva, P.; Palmiero, R.; Raso, G.; Retico, A.; Stumbo, S.; Tangaro, S.

    2003-09-01

    The GPCALMA (Grid Platform for Computer Assisted Library for MAmmography) collaboration involves several departments of physics, INFN (National Institute of Nuclear Physics) sections, and italian hospitals. The aim of this collaboration is developing a tool that can help radiologists in early detection of breast cancer. GPCALMA has built a large distributed database of digitised mammographic images (about 5500 images corresponding to 1650 patients) and developed a CAD (Computer Aided Detection) software which is integrated in a station that can also be used to acquire new images, as archive and to perform statistical analysis. The images (18×24 cm2, digitised by a CCD linear scanner with a 85 μm pitch and 4096 gray levels) are completely described: pathological ones have a consistent characterization with radiologist's diagnosis and histological data, non pathological ones correspond to patients with a follow up at least three years. The distributed database is realized throught the connection of all the hospitals and research centers in GRID tecnology. In each hospital local patients digital images are stored in the local database. Using GRID connection, GPCALMA will allow each node to work on distributed database data as well as local database data. Using its database the GPCALMA tools perform several analysis. A texture analysis, i.e. an automated classification on adipose, dense or glandular texture, can be provided by the system. GPCALMA software also allows classification of pathological features, in particular massive lesions (both opacities and spiculated lesions) analysis and microcalcification clusters analysis. The detection of pathological features is made using neural network software that provides a selection of areas showing a given "suspicion level" of lesion occurrence. The performance of the GPCALMA system will be presented in terms of the ROC (Receiver Operating Characteristic) curves. The results of GPCALMA system as "second reader" will also

  13. Energy efficiency design strategies for buildings with grid-connected photovoltaic systems

    NASA Astrophysics Data System (ADS)

    Yimprayoon, Chanikarn

    The building sector in the United States represents more than 40% of the nation's energy consumption. Energy efficiency design strategies and renewable energy are keys to reduce building energy demand. Grid-connected photovoltaic (PV) systems installed on buildings have been the fastest growing market in the PV industry. This growth poses challenges for buildings qualified to serve in this market sector. Electricity produced from solar energy is intermittent. Matching building electricity demand with PV output can increase PV system efficiency. Through experimental methods and case studies, computer simulations were used to investigate the priorities of energy efficiency design strategies that decreased electricity demand while producing load profiles matching with unique output profiles from PV. Three building types (residential, commercial, and industrial) of varying sizes and use patterns located in 16 climate zones were modeled according to ASHRAE 90.1 requirements. Buildings were analyzed individually and as a group. Complying with ASHRAE energy standards can reduce annual electricity consumption at least 13%. With energy efficiency design strategies, the reduction could reach up to 65%, making it possible for PV systems to meet reduced demands in residential and industrial buildings. The peak electricity demand reduction could be up to 71% with integration of strategies and PV. Reducing lighting power density was the best single strategy with high overall performances. Combined strategies such as zero energy building are also recommended. Electricity consumption reductions are the sum of the reductions from strategies and PV output. However, peak electricity reductions were less than their sum because they reduced peak at different times. The potential of grid stress reduction is significant. Investment incentives from government and utilities are necessary. The PV system sizes on net metering interconnection should not be limited by legislation existing in

  14. Optimal Wind Energy Integration in Large-Scale Electric Grids

    NASA Astrophysics Data System (ADS)

    Albaijat, Mohammad H.

    The major concern in electric grid operation is operating under the most economical and reliable fashion to ensure affordability and continuity of electricity supply. This dissertation investigates the effects of such challenges, which affect electric grid reliability and economic operations. These challenges are: 1. Congestion of transmission lines, 2. Transmission lines expansion, 3. Large-scale wind energy integration, and 4. Phaser Measurement Units (PMUs) optimal placement for highest electric grid observability. Performing congestion analysis aids in evaluating the required increase of transmission line capacity in electric grids. However, it is necessary to evaluate expansion of transmission line capacity on methods to ensure optimal electric grid operation. Therefore, the expansion of transmission line capacity must enable grid operators to provide low-cost electricity while maintaining reliable operation of the electric grid. Because congestion affects the reliability of delivering power and increases its cost, the congestion analysis in electric grid networks is an important subject. Consequently, next-generation electric grids require novel methodologies for studying and managing congestion in electric grids. We suggest a novel method of long-term congestion management in large-scale electric grids. Owing to the complication and size of transmission line systems and the competitive nature of current grid operation, it is important for electric grid operators to determine how many transmission lines capacity to add. Traditional questions requiring answers are "Where" to add, "How much of transmission line capacity" to add, and "Which voltage level". Because of electric grid deregulation, transmission lines expansion is more complicated as it is now open to investors, whose main interest is to generate revenue, to build new transmission lines. Adding a new transmission capacity will help the system to relieve the transmission system congestion, create

  15. Integrating Grid Services into the Cray XT4 Environment

    SciTech Connect

    NERSC; Cholia, Shreyas; Lin, Hwa-Chun Wendy

    2009-05-01

    The 38640 core Cray XT4"Franklin" system at the National Energy Research Scientific Computing Center (NERSC) is a massively parallel resource available to Department of Energy researchers that also provides on-demand grid computing to the Open Science Grid. The integration of grid services on Franklin presented various challenges, including fundamental differences between the interactive and compute nodes, a stripped down compute-node operating system without dynamic library support, a shared-root environment and idiosyncratic application launching. Inour work, we describe how we resolved these challenges on a running, general-purpose production system to provide on-demand compute, storage, accounting and monitoring services through generic grid interfaces that mask the underlying system-specific details for the end user.

  16. Smart Grid Integrity Attacks: Characterizations and Countermeasures

    SciTech Connect

    Annarita Giani; Eilyan Bitar; Miles McQueen; Pramod Khargonekar; Kameshwar Poolla

    2011-10-01

    Real power injections at loads and generators, and real power flows on selected lines in a transmission network are monitored, transmitted over a SCADA network to the system operator, and used in state estimation algorithms to make dispatch, re-balance and other energy management system [EMS] decisions. Coordinated cyber attacks of power meter readings can be arranged to be undetectable by any bad data detection algorithm. These unobservable attacks present a serious threat to grid operations. Of particular interest are sparse attacks that involve the compromise of a modest number of meter readings. An efficient algorithm to find all unobservable attacks [under standard DC load flow approximations] involving the compromise of exactly two power injection meters and an arbitrary number of power meters on lines is presented. This requires O(n2m) flops for a power system with n buses and m line meters. If all lines are metered, there exist canonical forms that characterize all 3, 4, and 5-sparse unobservable attacks. These can be quickly detected in power systems using standard graph algorithms. Known secure phase measurement units [PMUs] can be used as countermeasures against an arbitrary collection of cyber attacks. Finding the minimum number of necessary PMUs is NP-hard. It is shown that p + 1 PMUs at carefully chosen buses are sufficient to neutralize a collection of p cyber attacks.

  17. Suppression of zero-crossing distortion for single-phase grid-connected photovoltaic inverters with unipolar modulation

    NASA Astrophysics Data System (ADS)

    Zeng, Bin; Xu, Hong-bing; Chen, Kai; Chen, Jian-guo

    2013-10-01

    For single-phase grid-connected photovoltaic inverters, current-control with unipolar modulation can reduce the losses of power tubes and improve the efficiency compared with using the bipolar modulation. However, it suffers inherent zero-crossing distortion which is related to the grid current and voltage. In this paper, the reason for zero-crossing distortion is analyzed and simulated, also a novel current-control approach with commutating in advance is proposed to resolve this problem. This approach obtains a leading angle of the grid current by using the feedback of proportional-integral controller of the unipolar inverter, and then set the working mode of power tubes according to this angle through commutation.

  18. COMPARING UTILITY CONNECTED TO STAND ALONE MICRO-GRIDS: FROM THE VIEWPOINT OF A UTILITY ENGINEER

    SciTech Connect

    Hoffman, Michael G.; Russo, Bryan J.

    2011-06-23

    Project examples of grid connected micro grid & example of grid isolated micro grid: drivers – economic, environmental and financial tools to plan/design modeling software resource options, tools to plan/design generation types, fuel options and services to provide smooth transitions required equipment and software controls minimal expense to maximum functionality, real time operational interfaces, getting it built real world complications and advice. This paper is an attempt to present a broad overview of micro grids, project examples, modeling tools, technology options, practical and business insights to enable those interested in micro-grids to quickly come up to speed on the basics and potentially move forward on their own projects with the tools and resources presented. Knowledge and experience with electrical distribution systems will make such an effort easier.

  19. Redefining What's Possible for Renewable Energy: Grid Integration

    SciTech Connect

    Cochran, Jaquelin; Milligan, Michael; Bloom, Aaron; Lopez, Anthony; Mai, Trieu

    2015-01-22

    The Energy Department's National Renewable Energy Laboratory (NREL) is spearheading engineering innovations that will help optimize the entire energy system, and the lab's analysis capabilities complement that engineering work by identifying ways to integrate renewable energy effectively and economically. This 3-minute video shows how NREL research and analysis are redefining what’s possible for renewable energy on the grid.

  20. Analysis and experimental verification of new power flow control for grid-connected inverter with LCL filter in microgrid.

    PubMed

    Gu, Herong; Guan, Yajuan; Wang, Huaibao; Wei, Baoze; Guo, Xiaoqiang

    2014-01-01

    Microgrid is an effective way to integrate the distributed energy resources into the utility networks. One of the most important issues is the power flow control of grid-connected voltage-source inverter in microgrid. In this paper, the small-signal model of the power flow control for the grid-connected inverter is established, from which it can be observed that the conventional power flow control may suffer from the poor damping and slow transient response. While the new power flow control can mitigate these problems without affecting the steady-state power flow regulation. Results of continuous-domain simulations in MATLAB and digital control experiments based on a 32-bit fixed-point TMS320F2812 DSP are in good agreement, which verify the small signal model analysis and effectiveness of the proposed method. PMID:24672304

  1. Controlling of grid connected photovoltaic lighting system with fuzzy logic

    SciTech Connect

    Saglam, Safak; Ekren, Nazmi; Erdal, Hasan

    2010-02-15

    In this study, DC electrical energy produced by photovoltaic panels is converted to AC electrical energy and an indoor area is illuminated using this energy. System is controlled by fuzzy logic algorithm controller designed with 16 rules. Energy is supplied from accumulator which is charged by photovoltaic panels if its energy would be sufficient otherwise it is supplied from grid. During the 1-week usage period at the semester time, 1.968 kWh energy is used from grid but designed system used 0.542 kWh energy from photovoltaic panels at the experiments. Energy saving is determined by calculations and measurements for one education year period (9 months) 70.848 kWh. (author)

  2. Integrating heterogeneous rules-engine technologies with caGrid.

    PubMed

    Saltz, Joel H; Oster, Scott; Hastings, Shannon L; Langella, Stephen; Ervin, David; Payne, Philip R O

    2007-01-01

    The use of rules-engines spans multiple computational and biomedical domains. Within the NCIs caBIG program, the orchestration of grid-based computational workflow has used the BPEL standard. However, recent strategic planning within caBIG has raised questions about the applicability of BPEL for other rule definition and execution scenarios. In response, we have reviewed the current state of rules-engine technologies, and have formulated an architectural model for the integration of heterogeneous rules-engines with caGrid. PMID:18694196

  3. Robust path integration in the entorhinal grid cell system with hippocampal feed-back.

    PubMed

    Samu, Dávid; Eros, Péter; Ujfalussy, Balázs; Kiss, Tamás

    2009-07-01

    Animals are able to update their knowledge about their current position solely by integrating the speed and the direction of their movement, which is known as path integration. Recent discoveries suggest that grid cells in the medial entorhinal cortex might perform some of the essential underlying computations of path integration. However, a major concern over path integration is that as the measurement of speed and direction is inaccurate, the representation of the position will become increasingly unreliable. In this paper, we study how allothetic inputs can be used to continually correct the accumulating error in the path integrator system. We set up the model of a mobile agent equipped with the entorhinal representation of idiothetic (grid cell) and allothetic (visual cells) information and simulated its place learning in a virtual environment. Due to competitive learning, a robust hippocampal place code emerges rapidly in the model. At the same time, the hippocampo-entorhinal feed-back connections are modified via Hebbian learning in order to allow hippocampal place cells to influence the attractor dynamics in the entorhinal cortex. We show that the continuous feed-back from the integrated hippocampal place representation is able to stabilize the grid cell code. PMID:19381679

  4. Solar energy grid integration systems - Energy storage (SEGIS-ES)

    SciTech Connect

    Ton, Dan; Peek, Georgianne H.; Hanley, Charles; Boyes, John

    2008-05-01

    In late 2007, the U.S. Department of Energy (DOE) initiated a series of studies to address issues related to potential high penetration of distributed photovoltaic (PV) generation systems on our nation’s electric grid. This Renewable Systems Interconnection (RSI) initiative resulted in the publication of 14 reports and an Executive Summary that defined needs in areas related to utility planning tools and business models, new grid architectures and PV systems configurations, and models to assess market penetration and the effects of high-penetration PV systems. As a result of this effort, the Solar Energy Grid Integration Systems (SEGIS) program was initiated in early 2008. SEGIS is an industry-led effort to develop new PV inverters, controllers, and energy management systems that will greatly enhance the utility of distributed PV systems.

  5. Smart Energy Management and Control for Fuel Cell Based Micro-Grid Connected Neighborhoods

    SciTech Connect

    Dr. Mohammad S. Alam

    2006-03-15

    Fuel cell power generation promises to be an efficient, pollution-free, reliable power source in both large scale and small scale, remote applications. DOE formed the Solid State Energy Conversion Alliance with the intention of breaking one of the last barriers remaining for cost effective fuel cell power generation. The Alliance’s goal is to produce a core solid-state fuel cell module at a cost of no more than $400 per kilowatt and ready for commercial application by 2010. With their inherently high, 60-70% conversion efficiencies, significantly reduced carbon dioxide emissions, and negligible emissions of other pollutants, fuel cells will be the obvious choice for a broad variety of commercial and residential applications when their cost effectiveness is improved. In a research program funded by the Department of Energy, the research team has been investigating smart fuel cell-operated residential micro-grid communities. This research has focused on using smart control systems in conjunction with fuel cell power plants, with the goal to reduce energy consumption, reduce demand peaks and still meet the energy requirements of any household in a micro-grid community environment. In Phases I and II, a SEMaC was developed and extended to a micro-grid community. In addition, an optimal configuration was determined for a single fuel cell power plant supplying power to a ten-home micro-grid community. In Phase III, the plan is to expand this work to fuel cell based micro-grid connected neighborhoods (mini-grid). The economic implications of hydrogen cogeneration will be investigated. These efforts are consistent with DOE’s mission to decentralize domestic electric power generation and to accelerate the onset of the hydrogen economy. A major challenge facing the routine implementation and use of a fuel cell based mini-grid is the varying electrical demand of the individual micro-grids, and, therefore, analyzing these issues is vital. Efforts are needed to determine

  6. Integrated 3S Technology Used in Urban Grid Management

    NASA Astrophysics Data System (ADS)

    Zhao, H.; Wang, H.; Wu, W.; Wang, C.

    2014-11-01

    Sustainable development requires monitoring the state and changes of the city and providing the appropriate information to users anytime and anywhere. This paper takes Ningbo City as the research area, by utilizing two temporal (March 25, 2012 and November 25, 2013) ZY-3 satellite remote sensing data. 3S technology is used for urban grid management. The remote sensing information extraction of Ningbo City includes: extraction of building change information, extraction of green space change information, extraction of water information and analysis of eutrophication correspondingly. When extracting change information, we take "change information" as a special kind of "geographic information" to study the characteristics of different bands in multi-temporal data, and follow the first law of geography, namely adjacent similar principle. The extracted raster information is further converted into GIS vector format data as a basis for dynamic monitoring of Ningbo Urban Management systems: on the one hand, it can meet the demands of multi-source spatial data analysis (such as: overlay analysis, buffer analysis, etc.); on the other hand, it could meet the requirements of daily urban management. Dynamic monitoring system of Ningbo city management adopts the urban grid management mode. Based on GIS and GPS, grid management can satisfy the urban management mode -someone bear responsibility within the grid, somebody do the task under the supervision of the lattice, and at the same time play the role of remote sensing field surveying. To some extent, integrated 3S technology and urban grid management is a practical alternative of minimizing the uncertainty of remote sensing data and information extraction. With multi-scale and multi-dimensional remote sensing data, 3S integration and the urban grid management can monitor the urban state and its spatial-temporal changes. It's helpful for discovery and analysis of urban problems about resources, environment, ecology and disaster

  7. An integrated security framework for GOSS power grid analytics platform

    SciTech Connect

    Gibson, Tara D.; Ciraci, Selim; Sharma, Poorva; Allwardt, Craig H.; Rice, Mark J.; Akyol, Bora A.

    2014-06-23

    In power grid operations, security is an essential component for any middleware platform. Security protects data against unwanted access as well as cyber attacks. GridOpticsTM Software System (GOSS) is an open source power grid analytics platform that facilitates ease of access between applications and data sources and promotes development of advanced analytical applications. GOSS contains an API that abstracts many of the difficulties in connecting to various heterogeneous data sources. A number of applications and data sources have already been implemented to demonstrate functionality and ease of use. A security framework has been implemented which leverages widely accepted, robust JavaTM security tools in a way such that they can be interchanged as needed. This framework supports the complex fine-grained, access control rules identified for the diverse data sources already in GOSS. Performance and reliability are also important considerations in any power grid architecture. An evaluation is done to determine the overhead cost caused by security within GOSS and ensure minimal impact to performance.

  8. A model of grid cells involving extra hippocampal path integration, and the hippocampal loop.

    PubMed

    Gaussier, P; Banquet, J P; Sargolini, F; Giovannangeli, C; Save, E; Poucet, B

    2007-09-01

    In this paper, we present a model for the generation of grid cells and the emergence of place cells from multimodal input to the entorhinal cortex (EC). In this model, grid cell activity in the dorsocaudal medial entorhinal cortex (dMEC) [28] results from the operation of a long-distance path integration system located outside the hippocampal formation, presumably in retrosplenial and/or parietal cortex. If the connections between these structures and dMEC are organized as a modulo N operator, the resulting activity of dMEC neurons is a grid cell pattern. Furthermore, a robust high-resolution positional code can be built from a small set of different grid cells if the modulo factors are relatively prime. On the other hand, broad visual place cell activity in the MEC can result from the integration of visual information depending on the view-field of the visual input. The merging of entorhinal visual place cell information and grid cell information in the EC and/or in the dentate gyrus (DG) allows the building of precise and robust "place cells" (e.g., whose activity is maintained if light is suppressed for a short duration). Our model supports our previous proposition that hippocampal "place cell" activity code transitions between two successive states ("transition cells") rather than mere current locations. Furthermore, we discuss the possibility that the hippocampal loop participates in the emergence of grid cell activity but is not sufficient by itself. Finally, path integration at a short time scale (which is reset from one place to the next) would be merged in the subiculum with CA3/CA1 "transition cells" [22] to provide a robust feedback about current action to the deep layer of the entorhinal cortex in order to predict the recognition of the new animal location. PMID:17933021

  9. Decision making for best cogeneration power integration into a grid

    NASA Astrophysics Data System (ADS)

    Al Asmar, Joseph; Zakhia, Nadim; Kouta, Raed; Wack, Maxime

    2016-07-01

    Cogeneration systems are known to be efficient power systems for their ability to reduce pollution. Their integration into a grid requires simultaneous consideration of the economic and environmental challenges. Thus, an optimal cogeneration power are adopted to face such challenges. This work presents a novelty in selectinga suitable solution using heuristic optimization method. Its aim is to optimize the cogeneration capacity to be installed according to the economic and environmental concerns. This novelty is based on the sensitivity and data analysis method, namely, Multiple Linear Regression (MLR). This later establishes a compromise between power, economy, and pollution, which leads to find asuitable cogeneration power, and further, to be integrated into a grid. The data exploited were the results of the Genetic Algorithm (GA) multi-objective optimization. Moreover, the impact of the utility's subsidy on the selected power is shown.

  10. An Authentication Gateway for Integrated Grid and Cloud Access

    NASA Astrophysics Data System (ADS)

    Ciaschini, V.; Salomoni, D.

    2011-12-01

    The WNoDeS architecture, providing distributed, integrated access to both Cloud and Grid resources through virtualization technologies, makes use of an Authentication Gateway to support diverse authentication mechanisms. Three main use cases are foreseen, covering access via X.509 digital certificates, federated services like Shibboleth or Kerberos, and credit-based access. In this paper, we describe the structure of the WNoDeS authentication gateway.

  11. Connecting: Integrating Art across the Curriculum. [Multimedia Educational Kit].

    ERIC Educational Resources Information Center

    Unsworth, Jean Morman

    The idea of "connecting" is explored in this multimedia educational kit art for elementary schools. The Connecting series features a teacher's manual, six teacher's guides, and three videotapes based on six primary themes. These themes are: "Rhythms and Patterns"; "Change and Transformation"; "The World Our Minds Invent"; "Maps, Paths and Grids";…

  12. Multi-off-grid methods in multi-step integration of ordinary differential equations

    NASA Technical Reports Server (NTRS)

    Beaudet, P. R.

    1974-01-01

    Description of methods of solving first- and second-order systems of differential equations in which all derivatives are evaluated at off-grid locations in order to circumvent the Dahlquist stability limitation on the order of on-grid methods. The proposed multi-off-grid methods require off-grid state predictors for the evaluation of the n derivatives at each step. Progressing forward in time, the off-grid states are predicted using a linear combination of back on-grid state values and off-grid derivative evaluations. A comparison is made between the proposed multi-off-grid methods and the corresponding Adams and Cowell on-grid integration techniques in integrating systems of ordinary differential equations, showing a significant reduction in the error at larger step sizes in the case of the multi-off-grid integrator.

  13. Modeling Electric Vehicle Benefits Connected to Smart Grids

    SciTech Connect

    Stadler, Michael; Marnay, Chris; Mendes, Goncalo; Kloess, Maximillian; Cardoso, Goncalo; Mégel, Olivier; Siddiqui, Afzal

    2011-07-01

    Connecting electric storage technologies to smartgrids will have substantial implications in building energy systems. Local storage will enable demand response. Mobile storage devices in electric vehicles (EVs) are in direct competition with conventional stationary sources at the building. EVs will change the financial as well as environmental attractiveness of on-site generation (e.g. PV, or fuel cells). In order to examine the impact of EVs on building energy costs and CO2 emissions in 2020, a distributed-energy-resources adoption problem is formulated as a mixed-integer linear program with minimization of annual building energy costs or CO2 emissions. The mixed-integer linear program is applied to a set of 139 different commercial buildings in California and example results as well as the aggregated economic and environmental benefits are reported. The research shows that considering second life of EV batteries might be very beneficial for commercial buildings.

  14. GridOPTICS(TM) A Novel Software Framework for Integrating Power Grid Data Storage, Management and Analysis

    SciTech Connect

    Gorton, Ian; Yin, Jian; Akyol, Bora A.; Ciraci, Selim; Critchlow, Terence; Liu, Yan; Gibson, Tara D.; Purohit, Sumit; Sharma, Poorva; Vlachopoulou, Maria

    2013-01-09

    This paper describes the architecture and design of GridOPTICSTM, a novel software framework to integrate a collection of software tools developed by PNNL’s Future Power Grid Initiative (FPGI) into a coherent, powerful operations and planning tool for the power grid of the future. GridOPTICSTM enables plug-and-play of various analysis, modeling and visualization software tools for fast and accurate control of the power grid. To bridge the data access for different control purposes, GridOPTICSTM provides a scalable and thin layer of event processing that hides the complexity of data storage and management. The initial prototype of GridOPTICSTM was demonstrated with several use cases from PNNL’s FPGI.

  15. A generalized grid connectivity-based parameterization for subsurface flow model calibration

    NASA Astrophysics Data System (ADS)

    Bhark, Eric W.; Jafarpour, Behnam; Datta-Gupta, Akhil

    2011-06-01

    We develop a novel method of parameterization for spatial hydraulic property characterization to mitigate the challenges associated with the nonlinear inverse problem of subsurface flow model calibration. The parameterization is performed by the projection of the estimable hydraulic property field onto an orthonormal basis derived from the grid connectivity structure. The basis functions represent the modal shapes or harmonics of the grid, are defined by a modal frequency, and converge to special cases of the discrete Fourier series under certain grid geometries and boundary assumptions; therefore, hydraulic property updates are performed in the spectral domain and merge with Fourier analysis in ideal cases. Dependence on the grid alone implies that the basis may characterize any grid geometry, including corner point and unstructured, is model independent, and is constructed off-line and only once prior to flow data assimilation. We apply the parameterization in an adaptive multiscale model calibration workflow for three subsurface flow models. Several different grid geometries are considered. In each case the prior hydraulic property model is updated using a parameterized multiplier field that is superimposed onto the grid and assigned an initial value of unity at each cell. The special case corresponding to a constant multiplier is always applied through the constant basis function. Higher modes are adaptively employed during minimization of data misfit to resolve multiscale heterogeneity in the geomodel. The parameterization demonstrates selective updating of heterogeneity at locations and spatial scales sensitive to the available data, otherwise leaving the prior model unchanged as desired.

  16. Method for fabricating solar cells having integrated collector grids

    NASA Technical Reports Server (NTRS)

    Evans, J. C., Jr. (Inventor)

    1979-01-01

    A heterojunction or Schottky barrier photovoltaic device comprising a conductive base metal layer compatible with and coating predominately the exposed surface of the p-type substrate of the device such that a back surface field region is formed at the interface between the device and the base metal layer, a transparent, conductive mixed metal oxide layer in integral contact with the n-type layer of the heterojunction or Schottky barrier device having a metal alloy grid network of the same metal elements of the oxide constituents of the mixed metal oxide layer embedded in the mixed metal oxide layer, an insulating layer which prevents electrical contact between the conductive metal base layer and the transparent, conductive metal oxide layer, and a metal contact means covering the insulating layer and in intimate contact with the metal grid network embedded in the transparent, conductive oxide layer for conducting electrons generated by the photovoltaic process from the device.

  17. Rethinking the Future Grid: Integrated Nuclear Renewable Energy Systems: Preprint

    SciTech Connect

    Bragg-Sitton, S. M.; Boardman, R.; Ruth, M.; Zinaman, O.; Forsberg, C.

    2015-01-01

    The U.S. DOE is supporting research and development that could lead to more efficient utilization of clean energy generation sources, including renewable and nuclear options, to meet both grid demand and thermal energy needs in the industrial sector. One concept under consideration by the DOE-NE and DOE-EERE is tighter coupling of nuclear and renewable energy sources in a manner that better optimizes energy use for the combined electricity, industrial manufacturing, and transportation sectors. This integration concept has been referred to as a 'hybrid system' that is capable of apportioning thermal and electrical energy to first meet the grid demand (with appropriate power conversion systems), then utilizing excess thermal and, in some cases, electrical energy to drive a process that results in an additional product.

  18. Experiences of a grid connected solar array energy production

    NASA Astrophysics Data System (ADS)

    Hagymássy, Zoltán; Vántus, András

    2015-04-01

    Solar energy possibilities of Hungary are higher than in Central Europe generally. The Institute for Land Utilisation, Technology and Regional Development of the University of Debrecen installed a photovoltaic (PV) system. The PV system is structured into 3 subsystems (fields). The first subsystem has 24 pieces of Kyocera KC 120 W type modules, the second subsystem has 72 pieces of Siemens ST 40W, and the remaining has 72 pieces of Dunasolar DS 40W In order to be operable independently of each other three inverter modules (SB 2500) had been installed. The recorder can be connected directly to a desktop PC. Operating and meteorological dates are recorded by MS Excel every 15 minutes. The power plant is connected to a weather station, which contents a PT 100 type temperature and humidity combined measuring instrument, a CM 11 pyranometer, and a wind speed measuring instrument. The produced DC, and AC power, together with the produced energy are as well, and the efficiency can be determined for each used PV technology. The measured operating and meteorological dates are collected by Sunny Boy Control, produced by the SMA. The energy productions of the subsystems are measured continually and the subsystems are measured separately. As an expected, the produced energy of polycrystalline -Si PV module and monocrystalline -Si PV was higher than amorphous-Si PV module. It is well known that energy analysis is more suitable for energy balance when we design a system. The air temperature and the temperature of the panels and the global irradiation conditions were measured. In summertime the panel temperature reaches 60-80 degrees in a sunny day. The panel temperatures are in a spring sunny day approximately 30-40 degrees. It can be concluded that the global irradiation is a major impact feature to influence the amount of energy produced. The efficiency depends on several parameters (spectral distribution of the incoming light, temperature values, etc.). The energy efficiency

  19. Islanding detection technique using wavelet energy in grid-connected PV system

    NASA Astrophysics Data System (ADS)

    Kim, Il Song

    2016-08-01

    This paper proposes a new islanding detection method using wavelet energy in a grid-connected photovoltaic system. The method detects spectral changes in the higher-frequency components of the point of common coupling voltage and obtains wavelet coefficients by multilevel wavelet analysis. The autocorrelation of the wavelet coefficients can clearly identify islanding detection, even in the variations of the grid voltage harmonics during normal operating conditions. The advantage of the proposed method is that it can detect islanding condition the conventional under voltage/over voltage/under frequency/over frequency methods fail to detect. The theoretical method to obtain wavelet energies is evolved and verified by the experimental result.

  20. How to Integrate Variable Power Source into a Power Grid

    NASA Astrophysics Data System (ADS)

    Asano, Hiroshi

    This paper discusses how to integrate variable power source such as wind power and photovoltaic generation into a power grid. The intermittent renewable generation is expected to penetrate for less carbon intensive power supply system, but it causes voltage control problem in the distribution system, and supply-demand imbalance problem in a whole power system. Cooperative control of customers' energy storage equipment such as water heater with storage tank for reducing inverse power flow from the roof-top PV system, the operation technique using a battery system and the solar radiation forecast for stabilizing output of variable generation, smart charging of plug-in hybrid electric vehicles for load frequency control (LFC), and other methods to integrate variable power source with improving social benefits are surveyed.

  1. Integrating Gridded NASA Hydrological Data into CUAHSI HIS

    NASA Technical Reports Server (NTRS)

    Rui, Hualan; Teng, William; Vollmer, Bruce; Mocko, David M.; Beaudoing, Hiroko K.; Whiteaker, Tim; Valentine, David; Maidment, David; Hooper, Richard

    2011-01-01

    The amount of hydrological data available from NASA remote sensing and modeling systems is vast and ever-increasing;but, one challenge persists:increasing the usefulness of these data for, and thus their use by, end user communities. The Hydrology Data and Information Services Center (HDISC), part of the Goddard Earth Sciences DISC, has continually worked to better understand the hydrological data needs of different end users, to thus better able to bridge the gap between NASA data and end user communities. One effective strategy is integrating the data in to end user community tools and environments. There is an ongoing collaborative effort between NASA HDISC, NASA Hydrological Sciences Branch, and CUAHSI to integrate NASA gridded hydrology data in to the CUAHSI Hydrologic Information System (HIS).

  2. Implementation of fuzzy-sliding mode based control of a grid connected photovoltaic system.

    PubMed

    Menadi, Abdelkrim; Abdeddaim, Sabrina; Ghamri, Ahmed; Betka, Achour

    2015-09-01

    The present work describes an optimal operation of a small scale photovoltaic system connected to a micro-grid, based on both sliding mode and fuzzy logic control. Real time implementation is done through a dSPACE 1104 single board, controlling a boost chopper on the PV array side and a voltage source inverter (VSI) on the grid side. The sliding mode controller tracks permanently the maximum power of the PV array regardless of atmospheric condition variations, while The fuzzy logic controller (FLC) regulates the DC-link voltage, and ensures via current control of the VSI a quasi-total transit of the extracted PV power to the grid under a unity power factor operation. Simulation results, carried out via Matlab-Simulink package were approved through experiment, showing the effectiveness of the proposed control techniques. PMID:26243440

  3. Photovoltaic Grid-Connected Modeling and Characterization Based on Experimental Results

    PubMed Central

    Humada, Ali M.; Hojabri, Mojgan; Sulaiman, Mohd Herwan Bin; Hamada, Hussein M.; Ahmed, Mushtaq N.

    2016-01-01

    A grid-connected photovoltaic (PV) system operates under fluctuated weather condition has been modeled and characterized based on specific test bed. A mathematical model of a small-scale PV system has been developed mainly for residential usage, and the potential results have been simulated. The proposed PV model based on three PV parameters, which are the photocurrent, IL, the reverse diode saturation current, Io, the ideality factor of diode, n. Accuracy of the proposed model and its parameters evaluated based on different benchmarks. The results showed that the proposed model fitting the experimental results with high accuracy compare to the other models, as well as the I-V characteristic curve. The results of this study can be considered valuable in terms of the installation of a grid-connected PV system in fluctuated climatic conditions. PMID:27035575

  4. Photovoltaic Grid-Connected Modeling and Characterization Based on Experimental Results.

    PubMed

    Humada, Ali M; Hojabri, Mojgan; Sulaiman, Mohd Herwan Bin; Hamada, Hussein M; Ahmed, Mushtaq N

    2016-01-01

    A grid-connected photovoltaic (PV) system operates under fluctuated weather condition has been modeled and characterized based on specific test bed. A mathematical model of a small-scale PV system has been developed mainly for residential usage, and the potential results have been simulated. The proposed PV model based on three PV parameters, which are the photocurrent, IL, the reverse diode saturation current, Io, the ideality factor of diode, n. Accuracy of the proposed model and its parameters evaluated based on different benchmarks. The results showed that the proposed model fitting the experimental results with high accuracy compare to the other models, as well as the I-V characteristic curve. The results of this study can be considered valuable in terms of the installation of a grid-connected PV system in fluctuated climatic conditions. PMID:27035575

  5. Modular Cascaded H-Bridge Multilevel PV Inverter with Distributed MPPT for Grid-Connected Applications

    DOE PAGESBeta

    Xiao, Bailu; Hang, Lijun; Mei, Jun; Riley, Cameron; Tolbert, Leon M.; Ozpineci, Burak

    2014-09-04

    This paper presents a modular cascaded H-bridge multilevel photovoltaic (PV) inverter for single- or three-phase grid-connected applications. The modular cascaded multilevel topology helps to improve the efficiency and flexibility of PV systems. To realize better utilization of PV modules and maximize the solar energy extraction, a distributed maximum power point tracking (MPPT) control scheme is applied to both single-phase and three-phase multilevel inverters, which allows the independent control of each dc-link voltage. For three-phase grid-connected applications, PV mismatches may introduce unbalanced supplied power, leading to unbalanced grid current. To solve this issue, a control scheme with modulation compensation is alsomore » proposed. An experimental three-phase 7-level cascaded H-bridge inverter has been built utilizing 9 H-bridge modules (3 modules per phase). Each H-bridge module is connected to a 185 W solar panel. Simulation and experimental results are presented to verify the feasibility of the proposed approach.« less

  6. Modular Cascaded H-Bridge Multilevel PV Inverter with Distributed MPPT for Grid-Connected Applications

    SciTech Connect

    Xiao, Bailu; Hang, Lijun; Mei, Jun; Riley, Cameron; Tolbert, Leon M.; Ozpineci, Burak

    2014-09-04

    This paper presents a modular cascaded H-bridge multilevel photovoltaic (PV) inverter for single- or three-phase grid-connected applications. The modular cascaded multilevel topology helps to improve the efficiency and flexibility of PV systems. To realize better utilization of PV modules and maximize the solar energy extraction, a distributed maximum power point tracking (MPPT) control scheme is applied to both single-phase and three-phase multilevel inverters, which allows the independent control of each dc-link voltage. For three-phase grid-connected applications, PV mismatches may introduce unbalanced supplied power, leading to unbalanced grid current. To solve this issue, a control scheme with modulation compensation is also proposed. An experimental three-phase 7-level cascaded H-bridge inverter has been built utilizing 9 H-bridge modules (3 modules per phase). Each H-bridge module is connected to a 185 W solar panel. Simulation and experimental results are presented to verify the feasibility of the proposed approach.

  7. Dynamic analysis of combined photovoltaic source and synchronous generator connected to power grid

    NASA Astrophysics Data System (ADS)

    Mahabal, Divya

    In the world of expanding economy and technology, the energy demand is likely to increase even with the global efforts of saving and increasing energy efficiency. Higher oil prices, effects of greenhouse gases, and concerns over other environmental impacts gave way to Distributed Generation (DG). With adequate awareness and support, DG's can meet these rising energy demands at lower prices compared to conventional methods. Extensive research is taking place in different areas like fuel cells, photovoltaic cells, wind turbines, and gas turbines. DG's when connected to a grid increase the overall efficiency of the power grid. It is believed that three-fifth of the world's electricity would account for renewable energy by middle of 21st century. This thesis presents the dynamic analysis of a grid connected photovoltaic (PV) system and synchronous generator. A grid is considered as an infinite bus. The photovol-taic system and synchronous generator act as small scale distributed energy resources. The output of the photovoltaic system depends on the light intensity, temperature, and irradiance levels of sun. The maximum power point tracking and DC/AC converter are also modeled for the photovoltaic system. The PV system is connected to the grid through DC/AC system. Different combinations of PV and synchronous generator are modeled with the grid to study the dynamics of the proposed system. The dynamics of the test system is analyzed by subjecting the system to several disturbances under various conditions. All modules are individually modeled and con-nected using MATLAB/Simulink software package. Results from the study show that, as the penetration of renewable energy sources like PV increases into the power system, the dynamics of the system becomes faster. When considering cases such as load switching, PV cannot deliver more power as the performance of PV depends on environmental conditions. Synchronous generator in power system can produce the required amount of

  8. Solar Energy Grid Integration Systems -- Energy Storage (SEGIS-ES).

    SciTech Connect

    Hanley, Charles J.; Ton, Dan T.; Boyes, John D.; Peek, Georgianne Huff

    2008-07-01

    This paper describes the concept for augmenting the SEGIS Program (an industry-led effort to greatly enhance the utility of distributed PV systems) with energy storage in residential and small commercial applications (SEGIS-ES). The goal of SEGIS-ES is to develop electrical energy storage components and systems specifically designed and optimized for grid-tied PV applications. This report describes the scope of the proposed SEGIS-ES Program and why it will be necessary to integrate energy storage with PV systems as PV-generated energy becomes more prevalent on the nation's utility grid. It also discusses the applications for which energy storage is most suited and for which it will provide the greatest economic and operational benefits to customers and utilities. Included is a detailed summary of the various storage technologies available, comparisons of their relative costs and development status, and a summary of key R&D needs for PV-storage systems. The report concludes with highlights of areas where further PV-specific R&D is needed and offers recommendations about how to proceed with their development.

  9. Connections: A Model for Integrated Freshman Year Studies.

    ERIC Educational Resources Information Center

    Olds, Barbara M.; Miller, Ronald L.

    This document describes the development of a project called "Connections," at the Colorado School of Mines. "Connections" is an integrated series of active-learning courses and seminars that allow first-year engineering and science students to connect studies in engineering, physical science, social science, and humanities via a series of…

  10. Solar energy grid integration systems : final report of the Florida Solar Energy Center Team.

    SciTech Connect

    Ropp, Michael; Gonzalez, Sigifredo; Schaffer, Alan; Katz, Stanley; Perkinson, Jim; Bower, Ward Isaac; Prestero, Mark; Casey, Leo; Moaveni, Houtan; Click, David; Davis, Kristopher; Reedy, Robert; Kuszmaul, Scott S.; Sena-Henderson, Lisa; David, Carolyn; Akhil, Abbas Ali

    2012-03-01

    Initiated in 2008, the Solar Energy Grid Integration Systems (SEGIS) program is a partnership involving the U.S. DOE, Sandia National Laboratories, private sector companies, electric utilities, and universities. Projects supported under the program have focused on the complete-system development of solar technologies, with the dual goal of expanding utility-scale penetration and addressing new challenges of connecting large-scale solar installations in higher penetrations to the electric grid. The Florida Solar Energy Center (FSEC), its partners, and Sandia National Laboratories have successfully collaborated to complete the work under the third and final stage of the SEGIS initiative. The SEGIS program was a three-year, three-stage project that include conceptual design and market analysis in Stage 1, prototype development and testing in Stage 2, and moving toward commercialization in Stage 3. Under this program, the FSEC SEGIS team developed a comprehensive vision that has guided technology development that sets one methodology for merging photovoltaic (PV) and smart-grid technologies. The FSEC team's objective in the SEGIS project is to remove barriers to large-scale general integration of PV and to enhance the value proposition of photovoltaic energy by enabling PV to act as much as possible as if it were at the very least equivalent to a conventional utility power plant. It was immediately apparent that the advanced power electronics of these advanced inverters will go far beyond conventional power plants, making high penetrations of PV not just acceptable, but desirable. This report summarizes a three-year effort to develop, validate and commercialize Grid-Smart Inverters for wider photovoltaic utilization, particularly in the utility sector.

  11. PVUSA experience with power conversion for grid-connected photovoltaic systems

    SciTech Connect

    Stolte, W.

    1995-11-01

    The Photovoltaics for Utility Scale Application (PVUSA) project was established to demonstrate photovoltaic (PV) systems in grid-connected utility applications. One of PVUSA`s key objectives is to evaluate the performance, reliability, and cost of the PV balance of system (BOS). Power conditioning units (PCUs) are the interface between the dc PV arrays and the ac utility lines, and have proved to be the most critical element in grid-connected PV systems. There are five different models of PCUs at PVUSA`s Davis and Kerman sites. This report describes the design, testing, performance characteristics, and maintenance history of each of these PCUs. PVUSA required PCUs in the power range 25 kW to 500 kW which could operate automatically and reliably under changing conditions of sunlight and changing conditions on the utility grid. Although a number of manufacturers can provide PCUs in this power range, none of these PCUs have been produced in sufficient quantity to allow refinement of a particular model into the highly reliable unit needed for long-term, unattended operation. Factory tests were useful but limited by the inability to test under full power and changing power conditions. The inability to completely test PCUs at the factory resulted in difficulty during startup, field testing, and subsequent operation. PVUSA has made significant progress in understanding the requirements for PCUs in grid-connected PV applications and improving field performance. This record of PVUSA`s experience with a variety of PCUs is intended to help utilities and their suppliers identify and retain the good performance characteristics of PCUs, and to make improvements where necessary to meet the needs of utilities.

  12. Connectivity

    ERIC Educational Resources Information Center

    Grush, Mary, Ed.

    2006-01-01

    Connectivity has dramatically changed the landscape of higher education IT. From "on-demand" services for net-gen students and advanced eLearning systems for faculty, to high-performance computing grid resources for researchers, IT now provides more networked services than ever to connect campus constituents to each other and to the world.…

  13. Electricity storage for grid-connected household dwellings with PV panels

    SciTech Connect

    Mulder, Grietus; Six, Daan; Ridder, Fjo De

    2010-07-15

    Classically electricity storage for PV panels is mostly designed for stand-alone applications. In contrast, we focus in this article on houses connected to the grid with a small-scale storage to store a part of the solar power for postponed consumption within the day or the next days. In this way the house owner becomes less dependent on the grid and does only pay for the net shortage of his energy production. Local storage solutions pave the way for many new applications like omitting over-voltage of the line and bridging periods of power-line black-out. Since 2009 using self-consumption of PV energy is publicly encouraged in Germany, which can be realised by electric storage. This paper develops methods to determine the optimal storage size for grid-connected dwellings with PV panels. From measurements in houses we were able to establish calculation rules for sizing the storage. Two situations for electricity storage are covered: - the storage system is an optimum to cover most of the electricity needs; - it is an optimum for covering the peak power need of a dwelling. After these calculation rules a second step is needed to determine the size of the real battery. The article treats the aspects that should be taken into consideration before buying a specific battery like lead-acid and lithium-ion batteries. (author)

  14. Smart electric vehicle (EV) charging and grid integration apparatus and methods

    DOEpatents

    Gadh, Rajit; Mal, Siddhartha; Prabhu, Shivanand; Chu, Chi-Cheng; Sheikh, Omar; Chung, Ching-Yen; He, Lei; Xiao, Bingjun; Shi, Yiyu

    2015-05-05

    An expert system manages a power grid wherein charging stations are connected to the power grid, with electric vehicles connected to the charging stations, whereby the expert system selectively backfills power from connected electric vehicles to the power grid through a grid tie inverter (if present) within the charging stations. In more traditional usage, the expert system allows for electric vehicle charging, coupled with user preferences as to charge time, charge cost, and charging station capabilities, without exceeding the power grid capacity at any point. A robust yet accurate state of charge (SOC) calculation method is also presented, whereby initially an open circuit voltage (OCV) based on sampled battery voltages and currents is calculated, and then the SOC is obtained based on a mapping between a previously measured reference OCV (ROCV) and SOC. The OCV-SOC calculation method accommodates likely any battery type with any current profile.

  15. Coupling Electric Vehicles and Power Grid through Charging-In-Motion and Connected Vehicle Technology

    SciTech Connect

    Li, Jan-Mou; Jones, Perry T; Onar, Omer C; Starke, Michael R

    2014-01-01

    A traffic-assignment-based framework is proposed to model the coupling of transportation network and power grid for analyzing impacts of energy demand from electric vehicles on the operation of power distribution. Although the reverse can be investigated with the proposed framework as well, electricity flowing from a power grid to electric vehicles is the focus of this paper. Major variables in transportation network (including link flows) and power grid (including electricity transmitted) are introduced for the coupling. Roles of charging-in-motion technology and connected vehicle technology have been identified in the framework of supernetwork. A linkage (i.e. individual energy demand) between the two networks is defined to construct the supernetwork. To determine equilibrium of the supernetwork can also answer how many drivers are going to use the charging-in-motion services, in which locations, and at what time frame. An optimal operation plan of power distribution will be decided along the determination simultaneously by which we have a picture about what level of power demand from the grid is expected in locations during an analyzed period. Caveat of the framework and possible applications have also been discussed.

  16. Magnitude and Variability of Controllable Charge Capacity Provided by Grid Connected Plug-in Electric Vehicles

    SciTech Connect

    Scoffield, Don R; Smart, John; Salisbury, Shawn

    2015-03-01

    As market penetration of plug-in electric vehicles (PEV) increases over time, the number of PEVs charging on the electric grid will also increase. As the number of PEVs increases, their ability to collectively impact the grid increases. The idea of a large body of PEVs connected to the grid presents an intriguing possibility. If utilities can control PEV charging, it is possible that PEVs could act as a distributed resource to provide grid services. The technology required to control charging is available for modern PEVs. However, a system for wide-spread implementation of controllable charging, including robust communication between vehicles and utilities, is not currently present. Therefore, the value of controllable charging must be assessed and weighed against the cost of building and operating such as system. In order to grasp the value of PEV charge control to the utility, the following must be understood: 1. The amount of controllable energy and power capacity available to the utility 2. The variability of the controllable capacity from day to day and as the number of PEVs in the market increases.

  17. Detecting Functional Connectivity During Audiovisual Integration with MEG: A Comparison of Connectivity Metrics

    PubMed Central

    Carver, Frederick W.; Holroyd, Tom; Horwitz, Barry; Coppola, Richard

    2015-01-01

    Abstract In typical magnetoencephalography and/or electroencephalography functional connectivity analysis, researchers select one of several methods that measure a relationship between regions to determine connectivity, such as coherence, power correlations, and others. However, it is largely unknown if some are more suited than others for various types of investigations. In this study, the authors investigate seven connectivity metrics to evaluate which, if any, are sensitive to audiovisual integration by contrasting connectivity when tracking an audiovisual object versus connectivity when tracking a visual object uncorrelated with the auditory stimulus. The authors are able to assess the metrics' performances at detecting audiovisual integration by investigating connectivity between auditory and visual areas. Critically, the authors perform their investigation on a whole-cortex all-to-all mapping, avoiding confounds introduced in seed selection. The authors find that amplitude-based connectivity measures in the beta band detect strong connections between visual and auditory areas during audiovisual integration, specifically between V4/V5 and auditory cortices in the right hemisphere. Conversely, phase-based connectivity measures in the beta band as well as phase and power measures in alpha, gamma, and theta do not show connectivity between audiovisual areas. The authors postulate that while beta power correlations detect audiovisual integration in the current experimental context, it may not always be the best measure to detect connectivity. Instead, it is likely that the brain utilizes a variety of mechanisms in neuronal communication that may produce differential types of temporal relationships. PMID:25599264

  18. Detecting Functional Connectivity During Audiovisual Integration with MEG: A Comparison of Connectivity Metrics.

    PubMed

    Ard, Tyler; Carver, Frederick W; Holroyd, Tom; Horwitz, Barry; Coppola, Richard

    2015-08-01

    In typical magnetoencephalography and/or electroencephalography functional connectivity analysis, researchers select one of several methods that measure a relationship between regions to determine connectivity, such as coherence, power correlations, and others. However, it is largely unknown if some are more suited than others for various types of investigations. In this study, the authors investigate seven connectivity metrics to evaluate which, if any, are sensitive to audiovisual integration by contrasting connectivity when tracking an audiovisual object versus connectivity when tracking a visual object uncorrelated with the auditory stimulus. The authors are able to assess the metrics' performances at detecting audiovisual integration by investigating connectivity between auditory and visual areas. Critically, the authors perform their investigation on a whole-cortex all-to-all mapping, avoiding confounds introduced in seed selection. The authors find that amplitude-based connectivity measures in the beta band detect strong connections between visual and auditory areas during audiovisual integration, specifically between V4/V5 and auditory cortices in the right hemisphere. Conversely, phase-based connectivity measures in the beta band as well as phase and power measures in alpha, gamma, and theta do not show connectivity between audiovisual areas. The authors postulate that while beta power correlations detect audiovisual integration in the current experimental context, it may not always be the best measure to detect connectivity. Instead, it is likely that the brain utilizes a variety of mechanisms in neuronal communication that may produce differential types of temporal relationships. PMID:25599264

  19. Advances in Domain Connectivity for Overset Grids Using the X-Rays Approach

    NASA Technical Reports Server (NTRS)

    Chan, William M.; Kim, Noah; Pandya, Shishir A.

    2012-01-01

    Advances in automation and robustness of the X-rays approach to domain connectivity for overset grids are presented. Given the surface definition for each component that makes up a complex configuration, the determination of hole points with appropriate hole boundaries is automatically and efficiently performed. Improvements made to the original X-rays approach for identifying the minimum hole include an automated closure scheme for hole-cutters with open boundaries, automatic determination of grid points to be considered for blanking by each hole-cutter, and an adaptive X-ray map to economically handle components in close proximity. Furthermore, an automated spatially varying offset of the hole boundary from the minimum hole is achieved using a dual wall-distance function and an orphan point removal iteration process. Results using the new scheme are presented for a number of static and relative motion test cases on a variety of aerospace applications.

  20. Integration and validation of a data grid software

    NASA Astrophysics Data System (ADS)

    Carenton-Madiec, Nicolas; Berger, Katharina; Cofino, Antonio

    2014-05-01

    The Earth System Grid Federation (ESGF) Peer-to-Peer (P2P) is a software infrastructure for the management, dissemination, and analysis of model output and observational data. The ESGF grid is composed with several types of nodes which have different roles. About 40 data nodes host model outputs and datasets using thredds catalogs. About 25 compute nodes offer remote visualization and analysis tools. About 15 index nodes crawl data nodes catalogs and implement faceted and federated search in a web interface. About 15 Identity providers nodes manage accounts, authentication and authorization. Here we will present an actual size test federation spread across different institutes in different countries and a python test suite that were started in December 2013. The first objective of the test suite is to provide a simple tool that helps to test and validate a single data node and its closest index, compute and identity provider peer. The next objective will be to run this test suite on every data node of the federation and therefore test and validate every single node of the whole federation. The suite already implements nosetests, requests, myproxy-logon, subprocess, selenium and fabric python libraries in order to test both web front ends, back ends and security services. The goal of this project is to improve the quality of deliverable in a small developers team context. Developers are widely spread around the world working collaboratively and without hierarchy. This kind of working organization context en-lighted the need of a federated integration test and validation process.

  1. Artificial neural networks for control of a grid-connected rectifier/inverter under disturbance, dynamic and power converter switching conditions.

    PubMed

    Li, Shuhui; Fairbank, Michael; Johnson, Cameron; Wunsch, Donald C; Alonso, Eduardo; Proaño, Julio L

    2014-04-01

    Three-phase grid-connected converters are widely used in renewable and electric power system applications. Traditionally, grid-connected converters are controlled with standard decoupled d-q vector control mechanisms. However, recent studies indicate that such mechanisms show limitations in their applicability to dynamic systems. This paper investigates how to mitigate such restrictions using a neural network to control a grid-connected rectifier/inverter. The neural network implements a dynamic programming algorithm and is trained by using back-propagation through time. To enhance performance and stability under disturbance, additional strategies are adopted, including the use of integrals of error signals to the network inputs and the introduction of grid disturbance voltage to the outputs of a well-trained network. The performance of the neural-network controller is studied under typical vector control conditions and compared against conventional vector control methods, which demonstrates that the neural vector control strategy proposed in this paper is effective. Even in dynamic and power converter switching environments, the neural vector controller shows strong ability to trace rapidly changing reference commands, tolerate system disturbances, and satisfy control requirements for a faulted power system. PMID:24807951

  2. Roots and Connections: A Culturally Integrated Approach to EAL Instruction

    ERIC Educational Resources Information Center

    Apedaile, Sarah; Whitelaw, Cheryl

    2012-01-01

    This article describes a culturally integrated approach to teaching English as an Additional Language (EAL) through Roots and Connections: A Culturally Integrated ESL Curriculum for Community Orientation in Alberta. This was developed by the Centre for Intercultural Education to integrate intercultural sensitivity into English-language…

  3. Three Course Connections: Integrated Event Design

    ERIC Educational Resources Information Center

    Johnson, Corey W.; Pate, Joseph A.

    2013-01-01

    Integrated Event Design (IED) capitalizes on three distinct courses to achieve a blended course delivery: Event Management, Research and Evaluation (for undergraduate students), and Experiential Education (for graduate students). Through the use of an event management company metaphor that fully integrates the diverse curricular concepts, course…

  4. Automatic Integration Testbeds validation on Open Science Grid

    NASA Astrophysics Data System (ADS)

    Caballero, J.; Thapa, S.; Gardner, R.; Potekhin, M.

    2011-12-01

    A recurring challenge in deploying high quality production middleware is the extent to which realistic testing occurs before release of the software into the production environment. We describe here an automated system for validating releases of the Open Science Grid software stack that leverages the (pilot-based) PanDA job management system developed and used by the ATLAS experiment. The system was motivated by a desire to subject the OSG Integration Testbed to more realistic validation tests. In particular those which resemble to every extent possible actual job workflows used by the experiments thus utilizing job scheduling at the compute element (CE), use of the worker node execution environment, transfer of data to/from the local storage element (SE), etc. The context is that candidate releases of OSG compute and storage elements can be tested by injecting large numbers of synthetic jobs varying in complexity and coverage of services tested. The native capabilities of the PanDA system can thus be used to define jobs, monitor their execution, and archive the resulting run statistics including success and failure modes. A repository of generic workflows and job types to measure various metrics of interest has been created. A command-line toolset has been developed so that testbed managers can quickly submit "VO-like" jobs into the system when newly deployed services are ready for testing. A system for automatic submission has been crafted to send jobs to integration testbed sites, collecting the results in a central service and generating regular reports for performance and reliability.

  5. Analysis of grid connected induction generators driven by hydro/wind turbines under realistic system constraints

    SciTech Connect

    urthy, S.S.; Jha, C.S. ); Rao, P.S.N. )

    1990-03-01

    Results of an investigation dealing with the behavior of grid connected induction generators (GCIG) driven by typical prime movers such as mini-hydro/wind turbines are presented. Certain practical operational problems of such systems are identified. Analytical techniques are developed to study the behavior of such systems. The system consists of the induction generator (IG) feeding a 11 kV grid through a step up transformer and a transmission line. Terminal capacitors to compensate for the lagging VAR are included in the study. Computer simulation is carried out to predict the system performance at the given input power from the turbine. Effects of variations in grid voltage, frequency, input power and terminal capacitance on the machine and system performance are studied. Analysis of self excitation conditions on disconnection of supply has been carried out. Behavior of a 200 kW hydel system and 55/11 kW 22 kW wind driven system corresponding to actual field conditions are presented and discussed.

  6. Decentralized Energy Management System for Networked Microgrids in Grid-connected and Islanded Modes

    SciTech Connect

    Wang, Zhaoyu; Chen, Bokan; Wang, Jianhui; Kim, Jinho

    2015-06-17

    This paper proposes a decentralized energy management system (EMS) for the coordinated operation of networked Microgirds (MGs) in a distribution system. In the grid-connected mode, the distribution network operator (DNO) and each MG are considered as distinct entities with individual objectives to minimize their own operation costs. It is assumed that both dispatchable and renewable energy source (RES)-based distributed generators (DGs) exist in the distribution network and the networked MGs. In order to coordinate the operation of all entities, we apply a decentralized bi-level algorithm to solve the problem with the first level to conduct negotiations among all entities and the second level to update the non-converging penalties. In the islanded mode, the objective of each MG is to maintain a reliable power supply to its customers. In order to take into account the uncertainties of DG outputs and load consumption, we formulate the problems as two-stage stochastic programs. The first stage is to determine base generation setpoints based on the forecasts and the second stage is to adjust the generation outputs based on the realized scenarios. Case studies of a distribution system with networked MGs demonstrate the effectiveness of the proposed methodology in both grid-connected and islanded modes.

  7. A grid-connected photovoltaic power conversion system with single-phase multilevel inverter

    SciTech Connect

    Beser, Ersoy; Arifoglu, Birol; Camur, Sabri; Beser, Esra Kandemir

    2010-12-15

    This paper presents a grid-connected photovoltaic (PV) power conversion system based on a single-phase multilevel inverter. The proposed system fundamentally consists of PV arrays and a single-phase multilevel inverter structure. First, configuration and structural parts of the PV assisted inverter system are introduced in detail. To produce reference output voltage waves, a simple switching strategy based on calculating switching angles is improved. By calculated switching angles, the reference signal is produced as a multilevel shaped output voltage wave. The control algorithm and operational principles of the proposed system are explained. Operating PV arrays in the same load condition is a considerable point; therefore a simulation study is performed to arrange the PV arrays. After determining the number and connection types of the PV arrays, the system is configured through the arrangement of the PV arrays. The validity of the proposed system is verified through simulations and experimental study. The results demonstrate that the system can achieve lower total harmonic distortion (THD) on the output voltage and load current, and it is capable of operating synchronous and transferring power values having different characteristic to the grid. Hence, it is suitable to use the proposed configuration as a PV power conversion system in various applications. (author)

  8. Integrating grid-based and topological maps for mobile robot navigation

    SciTech Connect

    Thrun, S.; Buecken, A.

    1996-12-31

    Research on mobile robot navigation has produced two major paradigms for mapping indoor environments: grid-based and topological. While grid-based methods produce accurate metric maps, their complexity often prohibits efficient planning and problem solving in large-scale indoor environments. Topological maps, on the other hand, can be used much more efficiently, yet accurate and consistent topological maps are considerably difficult to learn in large-scale environments. This paper describes an approach that integrates both paradigms: grid-based and topological. Grid-based maps are learned using artificial neural networks and Bayesian integration. Topological maps are generated on top of the grid-based maps, by partitioning the latter into coherent regions. By combining both paradigms-grid-based and topological, the approach presented here gains the best of both worlds: accuracy/consistency and efficiency. The paper gives results for autonomously operating a mobile robot equipped with sonar sensors in populated multi-room environments.

  9. Making Connections: Intentional Teaching for Integrative Learning

    ERIC Educational Resources Information Center

    Higgs, Bettie, Ed.; Kilcommins, Shane, Ed.; Ryan, Tony, Ed.

    2010-01-01

    In this volume the authors document examples of programmes/courses/activities that are designed intentionally to build students' capacity to be integrative thinkers and learners. In doing so they try to analyse and name the learning that is taking place, and so make it visible to the reader. The work is intended as a resource for all those…

  10. Connecting Art, Learning, and Creativity: A Case for Curriculum Integration

    ERIC Educational Resources Information Center

    Marshall, Julia

    2005-01-01

    The author argues that "substantive" art integration harmonizes with contemporary postmodern thought in art education and represents a strategy for teaching art in a postmodern way. Bringing together theories from cognitive science and metaphor theory (specifically connection and projection), the author shows how substantive integration promotes…

  11. Bias in Human Path Integration Is Predicted by Properties of Grid Cells.

    PubMed

    Chen, Xiaoli; He, Qiliang; Kelly, Jonathan W; Fiete, Ila R; McNamara, Timothy P

    2015-06-29

    Accurate wayfinding is essential to the survival of many animal species and requires the ability to maintain spatial orientation during locomotion. One of the ways that humans and other animals stay spatially oriented is through path integration, which operates by integrating self-motion cues over time, providing information about total displacement from a starting point. The neural substrate of path integration in mammals may exist in grid cells, which are found in dorsomedial entorhinal cortex and presubiculum and parasubiculum in rats. Grid cells have also been found in mice, bats, and monkeys, and signatures of grid cell activity have been observed in humans. We demonstrate that distance estimation by humans during path integration is sensitive to geometric deformations of a familiar environment and show that patterns of path integration error are predicted qualitatively by a model in which locations in the environment are represented in the brain as phases of arrays of grid cells with unique periods and decoded by the inverse mapping from phases to locations. The periods of these grid networks are assumed to expand and contract in response to expansions and contractions of a familiar environment. Biases in distance estimation occur when the periods of the encoding and decoding grids differ. Our findings explicate the way in which grid cells could function in human path integration. PMID:26073138

  12. Differential Evolution Based IDWNN Controller for Fault Ride-Through of Grid-Connected Doubly Fed Induction Wind Generators

    PubMed Central

    Manonmani, N.; Subbiah, V.; Sivakumar, L.

    2015-01-01

    The key objective of wind turbine development is to ensure that output power is continuously increased. It is authenticated that wind turbines (WTs) supply the necessary reactive power to the grid at the time of fault and after fault to aid the flowing grid voltage. At this juncture, this paper introduces a novel heuristic based controller module employing differential evolution and neural network architecture to improve the low-voltage ride-through rate of grid-connected wind turbines, which are connected along with doubly fed induction generators (DFIGs). The traditional crowbar-based systems were basically applied to secure the rotor-side converter during the occurrence of grid faults. This traditional controller is found not to satisfy the desired requirement, since DFIG during the connection of crowbar acts like a squirrel cage module and absorbs the reactive power from the grid. This limitation is taken care of in this paper by introducing heuristic controllers that remove the usage of crowbar and ensure that wind turbines supply necessary reactive power to the grid during faults. The controller is designed in this paper to enhance the DFIG converter during the grid fault and this controller takes care of the ride-through fault without employing any other hardware modules. The paper introduces a double wavelet neural network controller which is appropriately tuned employing differential evolution. To validate the proposed controller module, a case study of wind farm with 1.5 MW wind turbines connected to a 25 kV distribution system exporting power to a 120 kV grid through a 30 km 25 kV feeder is carried out by simulation. PMID:26516636

  13. Differential Evolution Based IDWNN Controller for Fault Ride-Through of Grid-Connected Doubly Fed Induction Wind Generators.

    PubMed

    Manonmani, N; Subbiah, V; Sivakumar, L

    2015-01-01

    The key objective of wind turbine development is to ensure that output power is continuously increased. It is authenticated that wind turbines (WTs) supply the necessary reactive power to the grid at the time of fault and after fault to aid the flowing grid voltage. At this juncture, this paper introduces a novel heuristic based controller module employing differential evolution and neural network architecture to improve the low-voltage ride-through rate of grid-connected wind turbines, which are connected along with doubly fed induction generators (DFIGs). The traditional crowbar-based systems were basically applied to secure the rotor-side converter during the occurrence of grid faults. This traditional controller is found not to satisfy the desired requirement, since DFIG during the connection of crowbar acts like a squirrel cage module and absorbs the reactive power from the grid. This limitation is taken care of in this paper by introducing heuristic controllers that remove the usage of crowbar and ensure that wind turbines supply necessary reactive power to the grid during faults. The controller is designed in this paper to enhance the DFIG converter during the grid fault and this controller takes care of the ride-through fault without employing any other hardware modules. The paper introduces a double wavelet neural network controller which is appropriately tuned employing differential evolution. To validate the proposed controller module, a case study of wind farm with 1.5 MW wind turbines connected to a 25 kV distribution system exporting power to a 120 kV grid through a 30 km 25 kV feeder is carried out by simulation. PMID:26516636

  14. PREFACE: Nonlinearity and Geometry: connections with integrability Nonlinearity and Geometry: connections with integrability

    NASA Astrophysics Data System (ADS)

    Cieslinski, Jan L.; Ferapontov, Eugene V.; Kitaev, Alexander V.; Nimmo, Jonathan J. C.

    2009-10-01

    -component dispersionless Boussinesq-type system. T E Kouloukas and V G Papageorgiou introduce a family of nonparametric Yang-Baxter maps obtained by re-factorization of matrix polynomials of first degree. These maps are Poisson with respect to the Sklyanin bracket, and their degenerations are connected to known integrable systems on quad-graphs. S V Manakov and P M Santini apply a novel version of the inverse scattering transform based on Lax pairs in multidimensional commuting vector fields to the heavenly and Pavlov equations, establishing that their localized solutions evolve without breaking, and constructing the long-time behaviour of the corresponding Cauchy problems. Discretizations of integrable geometric models depend heavily on the coordinates used. M Nieszporski and A Sym show how to discretize Bianchi surfaces (associated with an elliptic version of the Ernst equation) in arbitrary parametrization. C Rogers and A Szereszewski study the Bäcklund transformation for L-isothermic surfaces in the original Bianchi formulation. They establish a connection between this transformation and a nonhomogeneous linear Schrödinger equation and construct a class of generalized Dupin cyclides. W K Schief, A Szereszewski and C Rogers study a classical system of equilibrium equations for shell membranes. Various examples of viable membrane geometries lead to remarkable geometric configurations such as generalized Dupin cyclides and L-minimal surfaces. A Sergyeyev constructs infinite hierarchies of nonlocal higher symmetries for the oriented associativity equations using the spectral problem. The hierarchies in question generalize those constructed by Chen, Kontsevich and Schwarz for the WDVV equations. J Shiraishi and Y Tutiya study an integro-differential equation which generalizes the periodic intermediate long wave equation. The kernel of the singular integral involved is a second order difference of the Weierstrass ζ-function. Using Sato's formulation, the authors

  15. ISOGA: Integrated Services Optical Grid Architecture for Emerging E-Science Collaborative Applications

    SciTech Connect

    Oliver Yu

    2008-11-28

    This final report describes the accomplishments in the ISOGA (Integrated Services Optical Grid Architecture) project. ISOGA enables efficient deployment of existing and emerging collaborative grid applications with increasingly diverse multimedia communication requirements over a wide-area multi-domain optical network grid; and enables collaborative scientists with fast retrieval and seamless browsing of distributed scientific multimedia datasets over a wide-area optical network grid. The project focuses on research and development in the following areas: the polymorphic optical network control planes to enable multiple switching and communication services simultaneously; the intelligent optical grid user-network interface to enable user-centric network control and monitoring; and the seamless optical grid dataset browsing interface to enable fast retrieval of local/remote dataset for visualization and manipulation.

  16. Design and implementation of spatial knowledge grid for integrated spatial analysis

    NASA Astrophysics Data System (ADS)

    Liu, Xiangnan; Guan, Li; Wang, Ping

    2006-10-01

    Supported by spatial information grid(SIG), the spatial knowledge grid (SKG) for integrated spatial analysis utilizes the middleware technology in constructing the spatial information grid computation environment and spatial information service system, develops spatial entity oriented spatial data organization technology, carries out the profound computation of the spatial structure and spatial process pattern on the basis of Grid GIS infrastructure, spatial data grid and spatial information grid (specialized definition). At the same time, it realizes the complex spatial pattern expression and the spatial function process simulation by taking the spatial intelligent agent as the core to establish space initiative computation. Moreover through the establishment of virtual geographical environment with man-machine interactivity and blending, complex spatial modeling, network cooperation work and spatial community decision knowledge driven are achieved. The framework of SKG is discussed systematically in this paper. Its implement flow and the key technology with examples of overlay analysis are proposed as well.

  17. Integrity of Bolted Angle Connections Subjected to Simulated Column Removal

    PubMed Central

    Weigand, Jonathan M.; Berman, Jeffrey W.

    2016-01-01

    Large-scale tests of steel gravity framing systems (SGFSs) have shown that the connections are critical to the system integrity, when a column suffers damage that compromises its ability to carry gravity loads. When supporting columns were removed, the SGFSs redistributed gravity loads through the development of an alternate load path in a sustained tensile configuration resulting from large vertical deflections. The ability of the system to sustain such an alternate load path depends on the capacity of the gravity connections to remain intact after undergoing large rotation and axial extension demands, for which they were not designed. This study experimentally evaluates the performance of steel bolted angle connections subjected to loading consistent with an interior column removal. The characteristic connection behaviors are described and the performance of multiple connection configurations are compared in terms of their peak resistances and deformation capacities. PMID:27110059

  18. Wind power stabilization to achieve proper grid connection using power convertor & DSP Controller

    NASA Astrophysics Data System (ADS)

    Shejal, B. D.; Jamge, S. B.

    2010-11-01

    The wind power sources are characterized by irregularity, instability 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. This fluctuating power will have its impact on power balance and voltage at the point of common coupling. Small variation of wind speed could cause a large variation in the extracted power. As a result, large voltage fluctuation may result in voltage variations outside the regulation limit at connection point. In this paper, a method has been developed to reduce output power fluctuations of a wind turbine with an energy storage system using stator side converter. The developed method has been tested through modeling a doubly fed wind turbine and a battery storage system, using SimPower Systems tools of MATLAB and simulated for operation as a grid connected system.

  19. 78 FR 12042 - Electric Grid Integration Technical Workshops

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-21

    ... Electricity Distribution System Workshop Discussion Summary and the Electricity Transmission System Workshop... Electricity Delivery Division, Office of Electricity Delivery and Energy Reliability, U.S. Department of... very broad scope of stakeholders from across all sectors of the electricity grid. This process...

  20. DISTRIBUTED GRID-CONNECTED PHOTOVOLTAIC POWER SYSTEM EMISSION OFFSET ASSESSMENT: STATISTICAL TEST OF SIMULATED- AND MEASURED-BASED DATA

    EPA Science Inventory

    This study assessed the pollutant emission offset potential of distributed grid-connected photovoltaic (PV) power systems. Computer-simulated performance results were utilized for 211 PV systems located across the U.S. The PV systems' monthly electrical energy outputs were based ...

  1. Implementation of high concentration photovoltaic grid connected power plant for training, research, innovation and solar electricity production

    NASA Astrophysics Data System (ADS)

    Barhdadi, A.; Benazzouz, A.; Fabrizio, B.; Verdilio, D.

    2015-04-01

    In this paper, performance monitoring program is applied to a grid-connected high concentration photovoltaic power plant in order to identify any operational problem and to make sure of its optimal and continuous power generation working conditions. A preventive maintenance plan was also established and proposed for the whole system.

  2. Integration, Continuity and a Connection with Probability Density Functions

    ERIC Educational Resources Information Center

    Samuels, M.

    2006-01-01

    This note considers functions of two variables which are continuous on a possibly unbounded closed region in [vertical bar]R[squared], and the functions of one variable obtained by integrating out the other variable over this region. The question of continuity of these functions is investigated, as are connections with joint density and marginal…

  3. Integration of Network Topological and Connectivity Properties for Neuroimaging Classification

    PubMed Central

    Jie, Biao; Gao, Wei; Wang, Qian; Wee, Chong-Yaw

    2014-01-01

    Rapid advances in neuroimaging techniques have provided an efficient and noninvasive way for exploring the structural and functional connectivity of the human brain. Quantitative measurement of abnormality of brain connectivity in patients with neurodegenerative diseases, such as mild cognitive impairment (MCI) and Alzheimer’s disease (AD), have also been widely reported, especially at a group level. Recently, machine learning techniques have been applied to the study of AD and MCI, i.e., to identify the individuals with AD/MCI from the healthy controls (HCs). However, most existing methods focus on using only a single property of a connectivity network, although multiple network properties, such as local connectivity and global topological properties, can potentially be used. In this paper, by employing multikernel based approach, we propose a novel connectivity based framework to integrate multiple properties of connectivity network for improving the classification performance. Specifically, two different types of kernels (i.e., vector-based kernel and graph kernel) are used to quantify two different yet complementary properties of the network, i.e., local connectivity and global topological properties. Then, multikernel learning (MKL) technique is adopted to fuse these heterogeneous kernels for neuroimaging classification. We test the performance of our proposed method on two different data sets. First, we test it on the functional connectivity networks of 12 MCI and 25 HC subjects. The results show that our method achieves significant performance improvement over those using only one type of network property. Specifically, our method achieves a classification accuracy of 91.9%, which is 10.8% better than those by single network-property-based methods. Then, we test our method for gender classification on a large set of functional connectivity networks with 133 infants scanned at birth, 1 year, and 2 years, also demonstrating very promising results. PMID

  4. Grid-connected polymer solar panels: initial considerations of cost, lifetime, and practicality.

    PubMed

    Medford, Andrew J; Lilliedal, Mathilde R; Jørgensen, Mikkel; Aarø, Dennis; Pakalski, Heinz; Fyenbo, Jan; Krebs, Frederik C

    2010-09-13

    Large solar panels were constructed from polymer solar cell modules prepared using full roll-to-roll (R2R) manufacture based on the previously published ProcessOne. The individual flexible polymer solar modules comprising multiple serially connected single cell stripes were joined electrically and laminated between a 4 mm tempered glass window and black Tetlar foil using two sheets of 0.5 mm thick ethylene vinyl acetate (EVA). The panels produced up to 8 W with solar irradiance of ~960 Wm⁻², and had outer dimensions of 1 m x 1.7 m with active areas up to 9180 cm². Panels were mounted on a tracking station and their output was grid connected between testing. Several generations of polymer solar cells and panel constructions were tested in this context to optimize the production of polymer solar panels. Cells lacking a R2R barrier layer were found to degrade due to diffusion of oxygen after less than a month, while R2R encapsulated cells showed around 50% degradation after 6 months but suffered from poor performance due to de-lamination during panel production. A third generation of panels with various barrier layers was produced to optimize the choice of barrier foil and it was found that the inclusion of a thin protective foil between the cell and the barrier foil is critical. The findings provide a preliminary foundation for the production and optimization of large-area polymer solar panels and also enabled a cost analysis of solar panels based on polymer solar cells. PMID:21165057

  5. Divergence preserving discrete surface integral methods for Maxwell's curl equations using non-orthogonal unstructured grids

    NASA Technical Reports Server (NTRS)

    Madsen, Niel K.

    1992-01-01

    Several new discrete surface integral (DSI) methods for solving Maxwell's equations in the time-domain are presented. These methods, which allow the use of general nonorthogonal mixed-polyhedral unstructured grids, are direct generalizations of the canonical staggered-grid finite difference method. These methods are conservative in that they locally preserve divergence or charge. Employing mixed polyhedral cells, (hexahedral, tetrahedral, etc.) these methods allow more accurate modeling of non-rectangular structures and objects because the traditional stair-stepped boundary approximations associated with the orthogonal grid based finite difference methods can be avoided. Numerical results demonstrating the accuracy of these new methods are presented.

  6. An infrastructure for the integration of geoscience instruments and sensors on the Grid

    NASA Astrophysics Data System (ADS)

    Pugliese, R.; Prica, M.; Kourousias, G.; Del Linz, A.; Curri, A.

    2009-04-01

    The Grid, as a computing paradigm, has long been in the attention of both academia and industry[1]. The distributed and expandable nature of its general architecture result to scalability and more efficient utilisation of the computing infrastructures. The scientific community, including that of geosciences, often handles problems with very high requirements in data processing, transferring, and storing[2,3]. This has raised the interest on Grid technologies but these are often viewed solely as an access gateway to HPC. Suitable Grid infrastructures could provide the geoscience community with additional benefits like those of sharing, remote access and control of scientific systems. These systems can be scientific instruments, sensors, robots, cameras and any other device used in geosciences. The solution for practical, general, and feasible Grid-enabling of such devices requires non-intrusive extensions on core parts of the current Grid architecture. We propose an extended version of an architecture[4] that can serve as the solution to the problem. The solution we propose is called Grid Instrument Element (IE) [5]. It is an addition to the existing core Grid parts; the Computing Element (CE) and the Storage Element (SE) that serve the purposes that their name suggests. The IE that we will be referring to, and the related technologies have been developed in the EU project on the Deployment of Remote Instrumentation Infrastructure (DORII1). In DORII, partners of various scientific communities including those of Earthquake, Environmental science, and Experimental science, have adopted the technology of the Instrument Element in order to integrate to the Grid their devices. The Oceanographic and coastal observation and modelling Mediterranean Ocean Observing Network (OGS2), a DORII partner, is in the process of deploying the above mentioned Grid technologies on two types of observational modules: Argo profiling floats and a novel Autonomous Underwater Vehicle (AUV

  7. Grid Integration and the Carrying Capacity of the U.S. Grid to Incorporate Variable Renewable Energy

    SciTech Connect

    Cochran, Jaquelin; Denholm, Paul; Speer, Bethany; Miller, Mackay

    2015-04-23

    In the United States and elsewhere, renewable energy (RE) generation supplies an increasingly large percentage of annual demand, including nine U.S. states where wind comprised over 10% of in-state generation in 2013. This white paper summarizes the challenges to integrating increasing amounts of variable RE, identifies emerging practices in power system planning and operation that can facilitate grid integration, and proposes a unifying concept—economic carrying capacity—that can provide a framework for evaluating actions to accommodate higher penetrations of RE. There is growing recognition that while technical challenges to variable RE integration are real, they can generally be addressed via a variety of solutions that vary in implementation cost. As a result, limits to RE penetration are primarily economic, driven by factors that include transmission and the flexibility of the power grid to balance supply and demand. This limit can be expressed as economic carrying capacity, or the point at which variable RE is no longer economically competitive or desirable to the system or society.

  8. Integrating Clinical Trial Imaging Data Resources Using Service-Oriented Architecture and Grid Computing

    PubMed Central

    Cladé, Thierry; Snyder, Joshua C.

    2010-01-01

    Clinical trials which use imaging typically require data management and workflow integration across several parties. We identify opportunities for all parties involved to realize benefits with a modular interoperability model based on service-oriented architecture and grid computing principles. We discuss middleware products for implementation of this model, and propose caGrid as an ideal candidate due to its healthcare focus; free, open source license; and mature developer tools and support. PMID:20449775

  9. Optimal Dispatch of Unreliable Electric Grid-Connected Diesel Generator-Battery Power Systems

    NASA Astrophysics Data System (ADS)

    Xu, D.; Kang, L.

    2015-06-01

    Diesel generator (DG)-battery power systems are often adopted by telecom operators, especially in semi-urban and rural areas of developing countries. Unreliable electric grids (UEG), which have frequent and lengthy outages, are peculiar to these regions. DG-UEG-battery power system is an important kind of hybrid power system. System dispatch is one of the key factors to hybrid power system integration. In this paper, the system dispatch of a DG-UEG-lead acid battery power system is studied with the UEG of relatively ample electricity in Central African Republic (CAR) and UEG of poor electricity in Congo Republic (CR). The mathematical models of the power system and the UEG are studied for completing the system operation simulation program. The net present cost (NPC) of the power system is the main evaluation index. The state of charge (SOC) set points and battery bank charging current are the optimization variables. For the UEG in CAR, the optimal dispatch solution is SOC start and stop points 0.4 and 0.5 that belong to the Micro-Cycling strategy and charging current 0.1 C. For the UEG in CR, the optimal dispatch solution is of 0.1 and 0.8 that belongs to the Cycle-Charging strategy and 0.1 C. Charging current 0.1 C is suitable for both grid scenarios compared to 0.2 C. It makes the dispatch strategy design easier in commercial practices that there are a few very good candidate dispatch solutions with system NPC values close to that of the optimal solution for both UEG scenarios in CAR and CR.

  10. Integration of a computational grid and virtual geographic environment to facilitate air pollution simulation

    NASA Astrophysics Data System (ADS)

    Xu, Bingli; Lin, Hui; Gong, Jianhua; Tang, Sammy; Hu, Ya; Nasser, Ibrahim Abdoul; Jing, Tao

    2013-04-01

    Air pollution, which is a global environmental problem, has been the hot research area among the scientists in the geoscience community. Air pollution simulation is of low-efficiency caused by the computation-intensive models, such as MM5 or WRF, and the complicated and unfriendly user interface. These issues are addressed in this paper by integrating computational grid and virtual geographic environment (VGE). The computational grid is employed to improve the computation efficiency of air pollution models. The VGE is used as a straightforward and easy to use interface to navigate the air pollution modeling workflow and improve the operational efficiencies of the models with respect to initiation, computation, and output visualization. On the aspect of technique implementation, this paper designs a framework and addresses the methodologies of the integration of computational grid and VGE. The prototype system, which integrates the computation grid of the Chinese University of Hong Kong (CUGrid) and a VGE to facilitate air pollution simulation based on the Mesoscale Model Version 5 (MM5), was developed. Based on the prototype system, a case was tested and the results indicate that the efficiencies of air pollution simulation on the model computation and workflow operation based on MM5 are increased significantly. This success also proves the reasonability of our general contribution of integrating computational grid and VGE to facilitate air pollution simulation.

  11. Transaction-Based Controls for Building-Grid Integration: VOLTTRON™

    SciTech Connect

    Akyol, Bora A.; Haack, Jereme N.; Hernandez, George; Katipamula, Srinivas; Widergren, Steven E.

    2015-07-01

    The U.S. Department of Energy’s (DOE’s) Building Technologies Office (BTO) is supporting the development of a “transactional network” concept that supports energy, operational, and financial transactions between building systems (e.g., rooftop units -- RTUs), and the electric power grid using applications, or 'agents', that reside either on the equipment, on local building controllers, or in the Cloud. The transactional network vision is delivered using a real-time, scalable reference platform called VOLTTRON that supports the needs of the changing energy system. VOLTTRON is an agent execution and an innovative distributed control and sensing software platform that supports modern control strategies, including agent-based and transaction-based controls. It enables mobile and stationary software agents to perform information gathering, processing, and control actions.

  12. Compatibility Study of Protective Relaying in a Grid-Connected Fuel Cell

    SciTech Connect

    Staunton, R.H.

    2004-04-15

    addressed other important and timely issues. For instance, the study includes an evaluation of the effectiveness of the fuel cell's synthesized relay protection scheme relative to the recently issued IEEE 1547 interconnection standard. Together, these activities should serve to reduce the number of unknowns pertaining to unconventional protective circuits, to the benefit of DG manufacturers, vendors, prospective and current users of DG, and electricity suppliers/distributors. Although more grid-connect fuel cell interruptions were encountered in this study than originally anticipated, and the investigation and findings became quite complex, every effort was made to clearly summarize the interconnection causes and issues throughout the report and especially in the summary found in Sect. 4. ORNL's funding of this study is sponsored equally by (1) the Department of Energy's (DOE's) Office of Distributed Energy Resources and (2) the Distributed Generation Technologies program of the Tennessee Valley Authority (TVA).

  13. Modeling and control of distributed energy systems during transition between grid connected and standalone modes

    NASA Astrophysics Data System (ADS)

    Arafat, Md Nayeem

    Distributed generation systems (DGs) have been penetrating into our energy networks with the advancement in the renewable energy sources and energy storage elements. These systems can operate in synchronism with the utility grid referred to as the grid connected (GC) mode of operation, or work independently, referred to as the standalone (SA) mode of operation. There is a need to ensure continuous power flow during transition between GC and SA modes, referred to as the transition mode, in operating DGs. In this dissertation, efficient and effective transition control algorithms are developed for DGs operating either independently or collectively with other units. Three techniques are proposed in this dissertation to manage the proper transition operations. In the first technique, a new control algorithm is proposed for an independent DG which can operate in SA and GC modes. The proposed transition control algorithm ensures low total harmonic distortion (THD) and less voltage fluctuation during mode transitions compared to the other techniques. In the second technique, a transition control is suggested for a collective of DGs operating in a microgrid system architecture to improve the reliability of the system, reduce the cost, and provide better performance. In this technique, one of the DGs in a microgrid system, referred to as a dispatch unit , takes the additional responsibility of mode transitioning to ensure smooth transition and supply/demand balance in the microgrid. In the third technique, an alternative transition technique is proposed through hybridizing the current and droop controllers. The proposed hybrid transition control technique has higher reliability compared to the dispatch unit concept. During the GC mode, the proposed hybrid controller uses current control. During the SA mode, the hybrid controller uses droop control. During the transition mode, both of the controllers participate in formulating the inverter output voltage but with different

  14. NREL Confirms Large Potential for Grid Integration of Wind, Solar Power (Fact Sheet)

    SciTech Connect

    Not Available

    2011-10-01

    To fully harvest the nation's bountiful wind and solar resources, it is critical to know how much electrical power from these renewable resources could be integrated reliably into the grid. To inform the discussion about the potential of such variable sources, the National Renewable Energy Laboratory (NREL) launched two key regional studies, examining the east and west sections of the U.S. power grid. The studies show that it is technically possible for U.S. power systems to integrate 20%-35% renewable electricity if infrastructure and operational improvements can be made.

  15. DICOMGrid: a middleware to integrate PACS and EELA-2 grid infrastructure

    NASA Astrophysics Data System (ADS)

    Moreno, Ramon A.; de Sá Rebelo, Marina; Gutierrez, Marco A.

    2010-03-01

    Medical images provide lots of information for physicians, but the huge amount of data produced by medical image equipments in a modern Health Institution is not completely explored in its full potential yet. Nowadays medical images are used in hospitals mostly as part of routine activities while its intrinsic value for research is underestimated. Medical images can be used for the development of new visualization techniques, new algorithms for patient care and new image processing techniques. These research areas usually require the use of huge volumes of data to obtain significant results, along with enormous computing capabilities. Such qualities are characteristics of grid computing systems such as EELA-2 infrastructure. The grid technologies allow the sharing of data in large scale in a safe and integrated environment and offer high computing capabilities. In this paper we describe the DicomGrid to store and retrieve medical images, properly anonymized, that can be used by researchers to test new processing techniques, using the computational power offered by grid technology. A prototype of the DicomGrid is under evaluation and permits the submission of jobs into the EELA-2 grid infrastructure while offering a simple interface that requires minimal understanding of the grid operation.

  16. Integration of HTS Cables in the Future Grid of the Netherlands

    NASA Astrophysics Data System (ADS)

    Zuijderduin, R.; Chevtchenko, O.; Smit, J. J.; Aanhaanen, G.; Melnik, I.; Geschiere, A.

    Due to increasing power demand, the electricity grid of the Netherlands is changing. The future transmission grid will obtain electrical power generated by decentralized renewable sources, together with large scale generation units located at the coastal region. In this way electrical power has to be distributed and transmitted over longer distances from generation to end user. Potential grid issues like: amount of distributed power, grid stability and electrical loss dissipation merit particular attention. High temperature superconductors (HTS) can play an important role in solving these grid problems. Advantages to integrate HTS components at transmission voltages are numerous: more transmittable power together with less emissions, intrinsic fault current limiting capability, lower ac loss, better control of power flow, reduced footprint, less magnetic field emissions, etc. The main obstacle at present is the relatively high price of HTS conductor. However as the price goes down, initial market penetration of several HTS components (e.g.: cables, fault current limiters) is expected by year 2015. In the full paper we present selected ways to integrate EHV AC HTS cables depending on a particular future grid scenario in the Netherlands.

  17. Seamless integration of data services between spatial information Grid and TeraGrid based on broker-based data management model

    NASA Astrophysics Data System (ADS)

    Zeng, Yi; Liu, Dingsheng; Li, Guoqing; Yu, Wenyang; Huang, Zhenchun; Song, Carol

    2009-10-01

    Most of the space agencies have built Grid systems to manage large volumes of spatial data archives and products. However, the heterogeneous data structure, the distributed storage location, and the gradual progress of building data service systems, make such spatial grid systems to be grid islands. The broker-based manage model can hide complexity and heterogeneity of spatial data sources, so that the research on broker-based data service is meaningful to promote inter-Grid collaboration for earth observation applications. This paper discusses the special problems of spatial information integration and some features of broker-based data management model. We demonstrate the prototype of building broker-based model to integrate heterogeneous data grid. This work securely provides querying and managing geospatial data and services, and transparent access to the related sources under Grid and Web Service environment. The paper also describe our experiences of case study on seamless integration with Purdue TeraGrid Data by using Storage Resource Broker, which is based on the extensible data service interfaces of China Spatial Information Grid.

  18. The Optimized Operation of Gas Turbine Combined Heat and Power Units Oriented for the Grid-Connected Control

    NASA Astrophysics Data System (ADS)

    Xia, Shu; Ge, Xiaolin

    2016-04-01

    In this study, according to various grid-connected demands, the optimization scheduling models of Combined Heat and Power (CHP) units are established with three scheduling modes, which are tracking the total generation scheduling mode, tracking steady output scheduling mode and tracking peaking curve scheduling mode. In order to reduce the solution difficulty, based on the principles of modern algebraic integers, linearizing techniques are developed to handle complex nonlinear constrains of the variable conditions, and the optimized operation problem of CHP units is converted into a mixed-integer linear programming problem. Finally, with specific examples, the 96 points day ahead, heat and power supply plans of the systems are optimized. The results show that, the proposed models and methods can develop appropriate coordination heat and power optimization programs according to different grid-connected control.

  19. Feasibility Study of Residential Grid-Connected Solar Photovoltaic Systems in the State of Indiana

    NASA Astrophysics Data System (ADS)

    Al-Odeh, Mahmoud

    This study aims to measure the financial viability of installing and using a residential grid-connected PV system in the State of Indiana while predicting its performance in eighteen geographical locations within the state over the system's expected lifetime. The null hypothesis of the study is that installing a PV system for a single family residence in the State of Indiana will not pay for itself within 25 years. Using a systematic approach consisting of six steps, data regarding the use of renewable energy in the State of Indiana was collected from the website of the US Department of Energy to perform feasibility analysis of the installation and use of a standard-sized residential PV system. The researcher was not able to reject the null hypothesis that installing a PV system for a single family residence in the State of Indiana will not pay for itself within 25 years. This study found that the standard PV system does not produce a positive project balance and does not pay for itself within 25 years (the life time of the system) assuming the average cost of a system. The government incentive programs are not enough to offset the cost of installing the system against the cost of the electricity that would not be purchased from the utility company. It can be concluded that the cost of solar PV is higher than the market valuation of the power it produces; thus, solar PV did not compete on the cost basis with the traditional competitive energy sources. Reducing the capital cost will make the standard PV system economically viable in Indiana. The study found that the capital cost for the system should be reduced by 15% - 56%.

  20. A 50 kilowatt distributed grid-connected photovoltaic generation system for the University of Wyoming

    SciTech Connect

    Chowdhury, B.H.; Muknahallipatna, S.; Cupal, J.J.; Hamann, J.C.; Dinwoodie, T.; Shugar, D.

    1997-12-31

    The University of Wyoming (UW) campus is serving as the site for a 50 kilowatt solar photovoltaic (PV) system. Three sub-systems were sited and built on the UW campus in 1996. The first sub-system, a 10 kW roof-integrated system of PV roof tiles is located on the roof of the Engineering building. The second sub-system--a 5 kW rack-mounted, ballasted PV system is on a walkway roof of the Engineering building. The third sub-system is a 35 kW shade structure system and located adjacent to the parking lot of the university`s football stadium. The three sub-systems differ in their design strategy since each is being used for research and education at the university. Each sub-system, being located at some distance away from one another, supplies a different part of the campus grid. Efforts continue at setting up a central monitoring system which will receive data remotely from all locations. A part of this monitoring system is complete. While the initial monitoring data shows satisfactory performance, a number of reliability problems with PV modules and inverters have delayed full functionality of the system.

  1. Connections beyond the margins of the power grid Information technology and the evolution of off-grid solar electricity in the developing world

    NASA Astrophysics Data System (ADS)

    Alstone, Peter Michael

    This work explores the intersections of information technology and off-grid electricity deployment in the developing world with focus on a key instance: the emergence of pay-as-you-go (PAYG) solar household-scale energy systems. It is grounded in detailed field study by my research team in Kenya between 2013-2014 that included primary data collection across the solar supply chain from global businesses through national and local distribution and to the end-users. We supplement the information with business process and national survey data to develop a detailed view of the markets, technology systems, and individuals who interact within those frameworks. The findings are presented in this dissertation as a series of four chapters with introductory, bridging, and synthesis material between them. The first chapter, Decentralized Energy Systems for Clean Electricity Access, presents a global view of the emerging off-grid power sector. Long-run trends in technology create "a unique moment in history" for closing the gap between global population and access to electricity, which has stubbornly held at 1-2 billion people without power since the initiation of the electric utility business model in the late 1800's. We show the potential for widespread near-term adoption of off-grid solar, which could lead to ten times less inequality in access and also ten times lower household-level climate impacts. Decentralized power systems that replace fuel-based incumbent lighting can advance the causes of climate stabilization, economic and social freedom and human health. Chapters two and three are focused on market and institutional dynamics present circa 2014 in for off-grid solar with a focus on the Kenya market. Chapter 2, "Off-grid Power and Connectivity", presents our findings related to the widespread influence of information technology across the supply chain for solar and in PAYG approaches. Using digital financing and embedded payment verification technology, PAYG

  2. Integrating reconfigurable hardware-based grid for high performance computing.

    PubMed

    Dondo Gazzano, Julio; Sanchez Molina, Francisco; Rincon, Fernando; López, Juan Carlos

    2015-01-01

    FPGAs have shown several characteristics that make them very attractive for high performance computing (HPC). The impressive speed-up factors that they are able to achieve, the reduced power consumption, and the easiness and flexibility of the design process with fast iterations between consecutive versions are examples of benefits obtained with their use. However, there are still some difficulties when using reconfigurable platforms as accelerator that need to be addressed: the need of an in-depth application study to identify potential acceleration, the lack of tools for the deployment of computational problems in distributed hardware platforms, and the low portability of components, among others. This work proposes a complete grid infrastructure for distributed high performance computing based on dynamically reconfigurable FPGAs. Besides, a set of services designed to facilitate the application deployment is described. An example application and a comparison with other hardware and software implementations are shown. Experimental results show that the proposed architecture offers encouraging advantages for deployment of high performance distributed applications simplifying development process. PMID:25874241

  3. Integrating Reconfigurable Hardware-Based Grid for High Performance Computing

    PubMed Central

    Dondo Gazzano, Julio; Sanchez Molina, Francisco; Rincon, Fernando; López, Juan Carlos

    2015-01-01

    FPGAs have shown several characteristics that make them very attractive for high performance computing (HPC). The impressive speed-up factors that they are able to achieve, the reduced power consumption, and the easiness and flexibility of the design process with fast iterations between consecutive versions are examples of benefits obtained with their use. However, there are still some difficulties when using reconfigurable platforms as accelerator that need to be addressed: the need of an in-depth application study to identify potential acceleration, the lack of tools for the deployment of computational problems in distributed hardware platforms, and the low portability of components, among others. This work proposes a complete grid infrastructure for distributed high performance computing based on dynamically reconfigurable FPGAs. Besides, a set of services designed to facilitate the application deployment is described. An example application and a comparison with other hardware and software implementations are shown. Experimental results show that the proposed architecture offers encouraging advantages for deployment of high performance distributed applications simplifying development process. PMID:25874241

  4. Reduction of a grid moire pattern by integrating a carbon-interspaced high precision x-ray grid with a digital radiographic detector

    SciTech Connect

    Yoon, Jai-Woong; Park, Young-Guk; Park, Chun-Joo; Kim, Do-Il; Lee, Jin-Ho; Chung, Nag-Kun; Choe, Bo-Young; Suh, Tae-Suk; Lee, Hyoung-Koo

    2007-11-15

    The stationary grid commonly used with a digital x-ray detector causes a moire interference pattern due to the inadequate sampling of the grid shadows by the detector pixels. There are limitations with the previous methods used to remove the moire such as imperfect electromagnetic interference shielding and the loss of image information. A new method is proposed for removing the moire pattern by integrating a carbon-interspaced high precision x-ray grid with high grid line uniformity with the detector for frequency matching. The grid was aligned to the detector by translating and rotating the x-ray grid with respect to the detector using microcontrolled alignment mechanism. The gap between the grid and the detector surface was adjusted with micrometer precision to precisely match the projected grid line pitch to the detector pixel pitch. Considering the magnification of the grid shadows on the detector plane, the grids were manufactured such that the grid line frequency was slightly higher than the detector sampling frequency. This study examined the factors that affect the moire pattern, particularly the line frequency and displacement. The frequency of the moire pattern was found to be sensitive to the angular displacement of the grid with respect to the detector while the horizontal translation alters the phase but not the moire frequency. The frequency of the moire pattern also decreased with decreasing difference in frequency between the grid and the detector, and a moire-free image was produced after complete matching for a given source to detector distance. The image quality factors including the contrast, signal-to-noise ratio and uniformity in the images with and without the moire pattern were investigated.

  5. Evaluating the performance of a 50 kilowatt grid-connected photovoltaic system

    SciTech Connect

    Chowdhury, B.H.; Muknahallipatn, S.; Cupal, J.J.; Hamann, J.C.

    1998-07-01

    A 50-kilowatt solar photovoltaic (PV) system was built at the University of Wyoming (UW) in 1996. The system comprises of three sub-systems. The first sub-system, a 10 kW roof-integrated system is located on the roof of the Engineering Building. The second sub-system is a 5 kW rack-mounted, ballasted PV system located on another part of the roof. The third sub-system is a 35 kW shade structure and is located adjacent to the university's football stadium. The three sub-systems differ in their design strategy since each is being used for research and education at the university. Each sub-system, being located at some distance away from one another, supplies a different part of the campus grid. Efforts are continuing for setting up a central monitoring system, which will receive data remotely from all locations. A part of this monitoring system is complete. The system as configured provides a great deal of flexibility, which is in turn demanded by the variety of signal types measured at each installation. Each installation requires measurement of multiple dc and ac voltages and currents and one slowly varying voltage (proportional to solar insolation). The simultaneous sampling, fast sample rate, and lowpass signal conditioning allow for accurate measurement of power factor and total harmonic distortion of the inverter outputs. Panel and inverter efficiencies can be determined via simultaneous DC and AC measurements. These performance monitors provide the essential data for characterization of the PV effect at the grid input, and enable the use of intelligent power factor correction and harmonic filtering. Monitoring of the system shows that the total harmonic distortion present in the ac power output is at or below the acceptable limit as recommended by IEEE 519-1992. The harmonic distortion worsens when the ac power reaches more than 3.8 kW. A number of reliability problems with PV modules and inverters have delayed full functionality of the system.

  6. A Stochastic Power Network Calculus for Integrating Renewable Energy Sources into the Power Grid

    SciTech Connect

    Wang, K; Ciucu, F; Lin, C; Low, SH

    2012-07-01

    Renewable energy such as solar and wind generation will constitute an important part of the future grid. As the availability of renewable sources may not match the load, energy storage is essential for grid stability. In this paper we investigate the feasibility of integrating solar photovoltaic (PV) panels and wind turbines into the grid by also accounting for energy storage. To deal with the fluctuation in both the power supply and demand, we extend and apply stochastic network calculus to analyze the power supply reliability with various renewable energy configurations. To illustrate the validity of the model, we conduct a case study for the integration of renewable energy sources into the power system of an island off the coast of Southern California. In particular, we asses the power supply reliability in terms of the average Fraction of Time that energy is Not-Served (FTNS).

  7. PREFACE: Nonlinearity and Geometry: connections with integrability Nonlinearity and Geometry: connections with integrability

    NASA Astrophysics Data System (ADS)

    Cieslinski, Jan L.; Ferapontov, Eugene V.; Kitaev, Alexander V.; Nimmo, Jonathan J. C.

    2009-10-01

    Geometric ideas are present in many areas of modern theoretical physics and they are usually associated with the presence of nonlinear phenomena. Integrable nonlinear systems play a prime role both in geometry itself and in nonlinear physics. One can mention general relativity, exact solutions of the Einstein equations, string theory, Yang-Mills theory, instantons, solitons in nonlinear optics and hydrodynamics, vortex dynamics, solvable models of statistical physics, deformation quantization, and many others. Soliton theory now forms a beautiful part of mathematics with very strong physical motivations and numerous applications. Interactions between mathematics and physics associated with integrability issues are very fruitful and stimulating. For instance, spectral theories of linear quantum mechanics turned out to be crucial for studying nonlinear integrable systems. The modern theory of integrable nonlinear partial differential and difference equations, or the `theory of solitons', is deeply rooted in the achievements of outstanding geometers of the end of the 19th and the beginning of the 20th century, such as Luigi Bianchi (1856-1928) and Jean Gaston Darboux (1842-1917). Transformations of surfaces and explicit constructions developed by `old' geometers were often rediscovered or reinterpreted in a modern framework. The great progress of recent years in so-called discrete geometry is certainly due to strong integrable motivations. A very remarkable feature of the results of the classical integrable geometry is the quite natural (although nontrivial) possibility of their discretization. This special issue is dedicated to Jean Gaston Darboux and his pioneering role in the development of the geometric ideas of modern soliton theory. The most famous aspects of his work are probably Darboux transformations and triply orthogonal systems of surfaces, whose role in modern mathematical physics cannot be overestimated. Indeed, Darboux transformations play a central

  8. Impact of language on functional connectivity for audiovisual speech integration.

    PubMed

    Shinozaki, Jun; Hiroe, Nobuo; Sato, Masa-Aki; Nagamine, Takashi; Sekiyama, Kaoru

    2016-01-01

    Visual information about lip and facial movements plays a role in audiovisual (AV) speech perception. Although this has been widely confirmed, previous behavioural studies have shown interlanguage differences, that is, native Japanese speakers do not integrate auditory and visual speech as closely as native English speakers. To elucidate the neural basis of such interlanguage differences, 22 native English speakers and 24 native Japanese speakers were examined in behavioural or functional Magnetic Resonance Imaging (fMRI) experiments while mono-syllabic speech was presented under AV, auditory-only, or visual-only conditions for speech identification. Behavioural results indicated that the English speakers identified visual speech more quickly than the Japanese speakers, and that the temporal facilitation effect of congruent visual speech was significant in the English speakers but not in the Japanese speakers. Using fMRI data, we examined the functional connectivity among brain regions important for auditory-visual interplay. The results indicated that the English speakers had significantly stronger connectivity between the visual motion area MT and the Heschl's gyrus compared with the Japanese speakers, which may subserve lower-level visual influences on speech perception in English speakers in a multisensory environment. These results suggested that linguistic experience strongly affects neural connectivity involved in AV speech integration. PMID:27510407

  9. Impact of language on functional connectivity for audiovisual speech integration

    PubMed Central

    Shinozaki, Jun; Hiroe, Nobuo; Sato, Masa-aki; Nagamine, Takashi; Sekiyama, Kaoru

    2016-01-01

    Visual information about lip and facial movements plays a role in audiovisual (AV) speech perception. Although this has been widely confirmed, previous behavioural studies have shown interlanguage differences, that is, native Japanese speakers do not integrate auditory and visual speech as closely as native English speakers. To elucidate the neural basis of such interlanguage differences, 22 native English speakers and 24 native Japanese speakers were examined in behavioural or functional Magnetic Resonance Imaging (fMRI) experiments while mono-syllabic speech was presented under AV, auditory-only, or visual-only conditions for speech identification. Behavioural results indicated that the English speakers identified visual speech more quickly than the Japanese speakers, and that the temporal facilitation effect of congruent visual speech was significant in the English speakers but not in the Japanese speakers. Using fMRI data, we examined the functional connectivity among brain regions important for auditory-visual interplay. The results indicated that the English speakers had significantly stronger connectivity between the visual motion area MT and the Heschl’s gyrus compared with the Japanese speakers, which may subserve lower-level visual influences on speech perception in English speakers in a multisensory environment. These results suggested that linguistic experience strongly affects neural connectivity involved in AV speech integration. PMID:27510407

  10. Metabolic connectivity as a driver of host and endosymbiont integration

    PubMed Central

    Karkar, Slim; Facchinelli, Fabio; Price, Dana C.; Weber, Andreas P. M.; Bhattacharya, Debashish

    2015-01-01

    The origin of oxygenic photosynthesis in the Archaeplastida common ancestor was foundational for the evolution of multicellular life. It is very likely that the primary endosymbiosis that explains plastid origin relied initially on the establishment of a metabolic connection between the host cell and captured cyanobacterium. We posit that these connections were derived primarily from existing host-derived components. To test this idea, we used phylogenomic and network analysis to infer the phylogenetic origin and evolutionary history of 37 validated plastid innermost membrane (permeome) metabolite transporters from the model plant Arabidopsis thaliana. Our results show that 57% of these transporter genes are of eukaryotic origin and that the captured cyanobacterium made a relatively minor (albeit important) contribution to the process. We also tested the hypothesis that the bacterium-derived hexose-phosphate transporter UhpC might have been the primordial sugar transporter in the Archaeplastida ancestor. Bioinformatic and protein localization studies demonstrate that this protein in the extremophilic red algae Galdieria sulphuraria and Cyanidioschyzon merolae are plastid targeted. Given this protein is also localized in plastids in the glaucophyte alga Cyanophora paradoxa, we suggest it played a crucial role in early plastid endosymbiosis by connecting the endosymbiont and host carbon storage networks. In summary, our work significantly advances understanding of plastid integration and favors a host-centric view of endosymbiosis. Under this view, nuclear genes of either eukaryotic or bacterial (noncyanobacterial) origin provided key elements of the toolkit needed for establishing metabolic connections in the primordial Archaeplastida lineage. PMID:25825767

  11. Metabolic connectivity as a driver of host and endosymbiont integration.

    PubMed

    Karkar, Slim; Facchinelli, Fabio; Price, Dana C; Weber, Andreas P M; Bhattacharya, Debashish

    2015-08-18

    The origin of oxygenic photosynthesis in the Archaeplastida common ancestor was foundational for the evolution of multicellular life. It is very likely that the primary endosymbiosis that explains plastid origin relied initially on the establishment of a metabolic connection between the host cell and captured cyanobacterium. We posit that these connections were derived primarily from existing host-derived components. To test this idea, we used phylogenomic and network analysis to infer the phylogenetic origin and evolutionary history of 37 validated plastid innermost membrane (permeome) metabolite transporters from the model plant Arabidopsis thaliana. Our results show that 57% of these transporter genes are of eukaryotic origin and that the captured cyanobacterium made a relatively minor (albeit important) contribution to the process. We also tested the hypothesis that the bacterium-derived hexose-phosphate transporter UhpC might have been the primordial sugar transporter in the Archaeplastida ancestor. Bioinformatic and protein localization studies demonstrate that this protein in the extremophilic red algae Galdieria sulphuraria and Cyanidioschyzon merolae are plastid targeted. Given this protein is also localized in plastids in the glaucophyte alga Cyanophora paradoxa, we suggest it played a crucial role in early plastid endosymbiosis by connecting the endosymbiont and host carbon storage networks. In summary, our work significantly advances understanding of plastid integration and favors a host-centric view of endosymbiosis. Under this view, nuclear genes of either eukaryotic or bacterial (noncyanobacterial) origin provided key elements of the toolkit needed for establishing metabolic connections in the primordial Archaeplastida lineage. PMID:25825767

  12. On computations of the integrated space shuttle flowfield using overset grids

    NASA Technical Reports Server (NTRS)

    Chiu, I-T.; Pletcher, R. H.; Steger, J. L.

    1990-01-01

    Numerical simulations using the thin-layer Navier-Stokes equations and chimera (overset) grid approach were carried out for flows around the integrated space shuttle vehicle over a range of Mach numbers. Body-conforming grids were used for all the component grids. Testcases include a three-component overset grid - the external tank (ET), the solid rocket booster (SRB) and the orbiter (ORB), and a five-component overset grid - the ET, SRB, ORB, forward and aft attach hardware, configurations. The results were compared with the wind tunnel and flight data. In addition, a Poisson solution procedure (a special case of the vorticity-velocity formulation) using primitive variables was developed to solve three-dimensional, irrotational, inviscid flows for single as well as overset grids. The solutions were validated by comparisons with other analytical or numerical solution, and/or experimental results for various geometries. The Poisson solution was also used as an initial guess for the thin-layer Navier-Stokes solution procedure to improve the efficiency of the numerical flow simulations. It was found that this approach resulted in roughly a 30 percent CPU time savings as compared with the procedure solving the thin-layer Navier-Stokes equations from a uniform free stream flowfield.

  13. Connecting multiple spatial scales to decode the population activity of grid cells

    PubMed Central

    Stemmler, Martin; Mathis, Alexander; Herz, Andreas V. M.

    2015-01-01

    Mammalian grid cells fire when an animal crosses the points of an imaginary hexagonal grid tessellating the environment. We show how animals can navigate by reading out a simple population vector of grid cell activity across multiple spatial scales, even though neural activity is intrinsically stochastic. This theory of dead reckoning explains why grid cells are organized into discrete modules within which all cells have the same lattice scale and orientation. The lattice scale changes from module to module and should form a geometric progression with a scale ratio of around 3/2 to minimize the risk of making large-scale errors in spatial localization. Such errors should also occur if intermediate-scale modules are silenced, whereas knocking out the module at the smallest scale will only affect spatial precision. For goal-directed navigation, the allocentric grid cell representation can be readily transformed into the egocentric goal coordinates needed for planning movements. The goal location is set by nonlinear gain fields that act on goal vector cells. This theory predicts neural and behavioral correlates of grid cell readout that transcend the known link between grid cells of the medial entorhinal cortex and place cells of the hippocampus. PMID:26824061

  14. Connecting multiple spatial scales to decode the population activity of grid cells.

    PubMed

    Stemmler, Martin; Mathis, Alexander; Herz, Andreas V M

    2015-12-01

    Mammalian grid cells fire when an animal crosses the points of an imaginary hexagonal grid tessellating the environment. We show how animals can navigate by reading out a simple population vector of grid cell activity across multiple spatial scales, even though neural activity is intrinsically stochastic. This theory of dead reckoning explains why grid cells are organized into discrete modules within which all cells have the same lattice scale and orientation. The lattice scale changes from module to module and should form a geometric progression with a scale ratio of around 3/2 to minimize the risk of making large-scale errors in spatial localization. Such errors should also occur if intermediate-scale modules are silenced, whereas knocking out the module at the smallest scale will only affect spatial precision. For goal-directed navigation, the allocentric grid cell representation can be readily transformed into the egocentric goal coordinates needed for planning movements. The goal location is set by nonlinear gain fields that act on goal vector cells. This theory predicts neural and behavioral correlates of grid cell readout that transcend the known link between grid cells of the medial entorhinal cortex and place cells of the hippocampus. PMID:26824061

  15. Semi-implicit integration factor methods on sparse grids for high-dimensional systems

    NASA Astrophysics Data System (ADS)

    Wang, Dongyong; Chen, Weitao; Nie, Qing

    2015-07-01

    Numerical methods for partial differential equations in high-dimensional spaces are often limited by the curse of dimensionality. Though the sparse grid technique, based on a one-dimensional hierarchical basis through tensor products, is popular for handling challenges such as those associated with spatial discretization, the stability conditions on time step size due to temporal discretization, such as those associated with high-order derivatives in space and stiff reactions, remain. Here, we incorporate the sparse grids with the implicit integration factor method (IIF) that is advantageous in terms of stability conditions for systems containing stiff reactions and diffusions. We combine IIF, in which the reaction is treated implicitly and the diffusion is treated explicitly and exactly, with various sparse grid techniques based on the finite element and finite difference methods and a multi-level combination approach. The overall method is found to be efficient in terms of both storage and computational time for solving a wide range of PDEs in high dimensions. In particular, the IIF with the sparse grid combination technique is flexible and effective in solving systems that may include cross-derivatives and non-constant diffusion coefficients. Extensive numerical simulations in both linear and nonlinear systems in high dimensions, along with applications of diffusive logistic equations and Fokker-Planck equations, demonstrate the accuracy, efficiency, and robustness of the new methods, indicating potential broad applications of the sparse grid-based integration factor method.

  16. Semi-implicit Integration Factor Methods on Sparse Grids for High-Dimensional Systems

    PubMed Central

    Wang, Dongyong; Chen, Weitao; Nie, Qing

    2015-01-01

    Numerical methods for partial differential equations in high-dimensional spaces are often limited by the curse of dimensionality. Though the sparse grid technique, based on a one-dimensional hierarchical basis through tensor products, is popular for handling challenges such as those associated with spatial discretization, the stability conditions on time step size due to temporal discretization, such as those associated with high-order derivatives in space and stiff reactions, remain. Here, we incorporate the sparse grids with the implicit integration factor method (IIF) that is advantageous in terms of stability conditions for systems containing stiff reactions and diffusions. We combine IIF, in which the reaction is treated implicitly and the diffusion is treated explicitly and exactly, with various sparse grid techniques based on the finite element and finite difference methods and a multi-level combination approach. The overall method is found to be efficient in terms of both storage and computational time for solving a wide range of PDEs in high dimensions. In particular, the IIF with the sparse grid combination technique is flexible and effective in solving systems that may include cross-derivatives and non-constant diffusion coefficients. Extensive numerical simulations in both linear and nonlinear systems in high dimensions, along with applications of diffusive logistic equations and Fokker-Planck equations, demonstrate the accuracy, efficiency, and robustness of the new methods, indicating potential broad applications of the sparse grid-based integration factor method. PMID:25897178

  17. Quantifying the Digital Divide: A Scientific Overview of Network Connectivity and Grid Infrastructure in South Asian Countries

    SciTech Connect

    Khan, Shahryar Muhammad; Cottrell, R.Les; Kalim, Umar; Ali, Arshad; /NUST, Rawalpindi

    2007-10-30

    The future of Computing in High Energy Physics (HEP) applications depends on both the Network and Grid infrastructure. South Asian countries such as India and Pakistan are making significant progress by building clusters as well as improving their network infrastructure However to facilitate the use of these resources, they need to manage the issues of network connectivity to be among the leading participants in Computing for HEP experiments. In this paper we classify the connectivity for academic and research institutions of South Asia. The quantitative measurements are carried out using the PingER methodology; an approach that induces minimal ICMP traffic to gather active end-to-end network statistics. The PingER project has been measuring the Internet performance for the last decade. Currently the measurement infrastructure comprises of over 700 hosts in more than 130 countries which collectively represents approximately 99% of the world's Internet-connected population. Thus, we are well positioned to characterize the world's connectivity. Here we present the current state of the National Research and Educational Networks (NRENs) and Grid Infrastructure in the South Asian countries and identify the areas of concern. We also present comparisons between South Asia and other developing as well as developed regions. We show that there is a strong correlation between the Network performance and several Human Development indices.

  18. Synchrophasor Sensing and Processing based Smart Grid Security Assessment for Renewable Energy Integration

    NASA Astrophysics Data System (ADS)

    Jiang, Huaiguang

    With the evolution of energy and power systems, the emerging Smart Grid (SG) is mainly featured by distributed renewable energy generations, demand-response control and huge amount of heterogeneous data sources. Widely distributed synchrophasor sensors, such as phasor measurement units (PMUs) and fault disturbance recorders (FDRs), can record multi-modal signals, for power system situational awareness and renewable energy integration. An effective and economical approach is proposed for wide-area security assessment. This approach is based on wavelet analysis for detecting and locating the short-term and long-term faults in SG, using voltage signals collected by distributed synchrophasor sensors. A data-driven approach for fault detection, identification and location is proposed and studied. This approach is based on matching pursuit decomposition (MPD) using Gaussian atom dictionary, hidden Markov model (HMM) of real-time frequency and voltage variation features, and fault contour maps generated by machine learning algorithms in SG systems. In addition, considering the economic issues, the placement optimization of distributed synchrophasor sensors is studied to reduce the number of the sensors without affecting the accuracy and effectiveness of the proposed approach. Furthermore, because the natural hazards is a critical issue for power system security, this approach is studied under different types of faults caused by natural hazards. A fast steady-state approach is proposed for voltage security of power systems with a wind power plant connected. The impedance matrix can be calculated by the voltage and current information collected by the PMUs. Based on the impedance matrix, locations in SG can be identified, where cause the greatest impact on the voltage at the wind power plants point of interconnection. Furthermore, because this dynamic voltage security assessment method relies on time-domain simulations of faults at different locations, the proposed approach

  19. Integrated Design Engineering Analysis (IDEA) Environment Automated Generation of Structured CFD Grids using Topology Methods

    NASA Technical Reports Server (NTRS)

    Kamhawi, Hilmi N.

    2012-01-01

    This report documents the work performed from March 2010 to March 2012. The Integrated Design and Engineering Analysis (IDEA) environment is a collaborative environment based on an object-oriented, multidisciplinary, distributed framework using the Adaptive Modeling Language (AML) as a framework and supporting the configuration design and parametric CFD grid generation. This report will focus on describing the work in the area of parametric CFD grid generation using novel concepts for defining the interaction between the mesh topology and the geometry in such a way as to separate the mesh topology from the geometric topology while maintaining the link between the mesh topology and the actual geometry.

  20. Thin Film Electrodes with an Integral Current Collection Grid for Use with Solid Electrolytes

    NASA Technical Reports Server (NTRS)

    Ryan, M. A.; Kisor, A.; Williams, R. M.; Jeffries-Nakamura, B.; O'Connor, D.

    1994-01-01

    Thin film, high performance electrodes which can operate in high temperature environments are necessary for many devices which use a solid electrolyte. Electrodes of rhodium-tungsten alloy have been deposited on solid electrolyte using photolytic chemical vapor deposition (PCVD). A technique for depositing electrodes and current collection grids simultaneously has been developed using the prenucleation characteristics of PCVD. This technique makes it possible to fabricate electrodes which allow vapor transport through the thin (<1 (micro)m) portions of the electrode while integral thick grid lines improve the electronic conductivity of the electrode, thus improving overall performance.

  1. Examination of circulation, dispersion, and connectivity in Lunenburg Bay of Nova Scotia using a nested-grid circulation model

    NASA Astrophysics Data System (ADS)

    Sheng, Jinyu; Zhao, Jun; Zhai, Li

    2009-05-01

    A coastal ocean observatory has been established in Lunenburg Bay, Nova Scotia since summer 2002 as part of a multi-agency research program of marine environmental observation and prediction over Atlantic Canada coastal waters. The observatory was operational when a category-2 hurricane (Juan) made land fall within 50-km of the bay in September 2003. The coastal response of the bay to Hurricane Juan is examined using a nested-grid coastal circulation modelling system. The nested-grid system is forced by the local wind, tides, and remotely generated coastal waves. A comparison of model results with observed surface elevations and currents demonstrates that the nested-grid system has reasonable skills in simulating the three-dimensional (3D) storm-induced circulation in the study region. The 3D model currents are used to examine the transport and dispersion of passive tracers, local flushing time, and retention and connectivity of passive particles in the bay during Hurricane Juan. Numerical results demonstrate that local wind forcing plays a dominant role in generating large dispersion and hydrodynamic connectivity in the bay during the storm.

  2. SchizConnect: Virtual Data Integration in Neuroimaging

    PubMed Central

    Ambite, Jose Luis; Tallis, Marcelo; Alpert, Kathryn; Keator, David B.; King, Margaret; Landis, Drew; Konstantinidis, George; Calhoun, Vince D.; Potkin, Steven G.; Turner, Jessica A.; Wang, Lei

    2015-01-01

    In many scientific domains, including neuroimaging studies, there is a need to obtain increasingly larger cohorts to achieve the desired statistical power for discovery. However, the economics of imaging studies make it unlikely that any single study or consortia can achieve the desired sample sizes. What is needed is an architecture that can easily incorporate additional studies as they become available. We present such architecture based on a virtual data integration approach, where data remains at the original sources, and is retrieved and harmonized in response to user queries. This is in contrast to approaches that move the data to a central warehouse. We implemented our approach in the SchizConnect system that integrates data from three neuroimaging consortia on Schizophrenia: FBIRN's Human Imaging Database (HID), MRN's Collaborative Imaging and Neuroinformatics System (COINS), and the NUSDAST project at XNAT Central. A portal providing harmonized access to these sources is publicly deployed at schizconnect.org. PMID:26688837

  3. Microcoil Spring Interconnects for Ceramic Grid Array Integrated Circuits

    NASA Technical Reports Server (NTRS)

    Strickland, S. M.; Hester, J. D.; Gowan, A. K.; Montgomery, R. K.; Geist, D. L.; Blanche, J. F.; McGuire, G. D.; Nash, T. S.

    2011-01-01

    As integrated circuit miniaturization trends continue, they drive the need for smaller higher input/output (I/O) packages. Hermetically sealed ceramic area array parts are the package of choice by the space community for high reliability space flight electronic hardware. Unfortunately, the coefficient of thermal expansion mismatch between the ceramic area array package and the epoxy glass printed wiring board limits the life of the interconnecting solder joint. This work presents the results of an investigation by Marshall Space Flight Center into a method to increase the life of this second level interconnection by the use of compliant microcoil springs. The design of the spring and its attachment process are presented along with thermal cycling results of microcoil springs (MCS) compared with state-of-the-art ball and column interconnections. Vibration testing has been conducted on MCS and high lead column parts. Radio frequency simulation and measurements have been made and the MCS has been modeled and a stress analysis performed. Thermal cycling and vibration testing have shown MCS interconnects to be significantly more reliable than solder columns. Also, MCS interconnects are less prone to handling damage than solder columns. Future work that includes shock testing, incorporation into a digital signal processor board, and process evaluation of expansion from a 400 I/O device to a device with over 1,100 I/O is identified.

  4. Neighborhood Integration and Connectivity Predict Cognitive Performance and Decline

    PubMed Central

    Watts, Amber; Ferdous, Farhana; Moore, Keith Diaz; Burns, Jeffrey M.

    2015-01-01

    Objective Neighborhood characteristics may be important for promoting walking, but little research has focused on older adults, especially those with cognitive impairment. We evaluated the role of neighborhood characteristics on cognitive function and decline over a 2-year period adjusting for measures of walking. Method In a study of 64 older adults with and without mild Alzheimer's disease (AD), we evaluated neighborhood integration and connectivity using geographical information systems data and space syntax analysis. In multiple regression analyses, we used these characteristics to predict 2-year declines in factor analytically derived cognitive scores (attention, verbal memory, mental status) adjusting for age, sex, education, and self-reported walking. Results Neighborhood integration and connectivity predicted cognitive performance at baseline, and changes in cognitive performance over 2 years. The relationships between neighborhood characteristics and cognitive performance were not fully explained by self-reported walking. Discussion Clearer definitions of specific neighborhood characteristics associated with walkability are needed to better understand the mechanisms by which neighborhoods may impact cognitive outcomes. These results have implications for measuring neighborhood characteristics, design and maintenance of living spaces, and interventions to increase walking among older adults. We offer suggestions for future research measuring neighborhood characteristics and cognitive function. PMID:26504889

  5. Separator-Integrated, Reversely Connectable Symmetric Lithium-Ion Battery.

    PubMed

    Wang, Yuhang; Zeng, Jiren; Cui, Xiaoqi; Zhang, Lijuan; Zheng, Gengfeng

    2016-02-24

    A separator-integrated, reversely connectable, symmetric lithium-ion battery is developed based on carbon-coated Li3V2(PO4)3 nanoparticles and polyvinylidene fluoride-treated separators. The Li3V2(PO4)3 nanoparticles are synthesized via a facile solution route followed by calcination in Ar/H2 atmosphere. Sucrose solution is used as the carbon source for uniform carbon coating on the Li3V2(PO4)3 nanoparticles. Both the carbon and the polyvinylidene fluoride treatments substantially improve the cycling life of the symmetric battery by preventing the dissolution and shuttle of the electroactive Li3V2(PO4)3. The obtained symmetric full cell exhibits a reversible capacity of ≈ 87 mA h g(-1), good cycling stability, and capacity retention of ≈ 70% after 70 cycles. In addition, this type of symmetric full cell can be operated in both forward and reverse connection modes, without any influence on the cycling of the battery. Furthermore, a new separator integration approach is demonstrated, which enables the direct deposition of electroactive materials for the battery assembly and does not affect the electrochemical performance. A 10-tandem-cell battery assembled without differentiating the electrode polarity exhibits a low thickness of ≈ 4.8 mm and a high output voltage of 20.8 V. PMID:26725040

  6. Integrating DICOM structure reporting (SR) into the medical imaging informatics data grid

    NASA Astrophysics Data System (ADS)

    Lee, Jasper; Le, Anh; Liu, Brent

    2008-03-01

    The Medical Imaging Informatics (MI2) Data Grid developed at the USC Image Processing and Informatics Laboratory enables medical images to be shared securely between multiple imaging centers. Current applications include an imaging-based clinical trial setting where multiple field sites perform image acquisition and a centralized radiology core performs image analysis, often using computer-aided diagnosis tools (CAD) that generate a DICOM-SR to report their findings and measurements. As more and more CAD tools are being developed in the radiology field, the generated DICOM Structure Reports (SR) holding key radiological findings and measurements that are not part of the DICOM image need to be integrated into the existing Medical Imaging Informatics Data Grid with the corresponding imaging studies. We will discuss the significance and method involved in adapting DICOM-SR into the Medical Imaging Informatics Data Grid. The result is a MI2 Data Grid repository from which users can send and receive DICOM-SR objects based on the imaging-based clinical trial application. The services required to extract and categorize information from the structured reports will be discussed, and the workflow to store and retrieve a DICOM-SR file into the existing MI2 Data Grid will be shown.

  7. Exact Integrations of Polynomials and Symmetric Quadrature Formulas over Arbitrary Polyhedral Grids

    NASA Technical Reports Server (NTRS)

    Liu, Yen; Vinokur, Marcel

    1997-01-01

    This paper is concerned with two important elements in the high-order accurate spatial discretization of finite volume equations over arbitrary grids. One element is the integration of basis functions over arbitrary domains, which is used in expressing various spatial integrals in terms of discrete unknowns. The other consists of quadrature approximations to those integrals. Only polynomial basis functions applied to polyhedral and polygonal grids are treated here. Non-triangular polygonal faces are subdivided into a union of planar triangular facets, and the resulting triangulated polyhedron is subdivided into a union of tetrahedra. The straight line segment, triangle, and tetrahedron are thus the fundamental shapes that are the building blocks for all integrations and quadrature approximations. Integrals of products up to the fifth order are derived in a unified manner for the three fundamental shapes in terms of the position vectors of vertices. Results are given both in terms of tensor products and products of Cartesian coordinates. The exact polynomial integrals are used to obtain symmetric quadrature approximations of any degree of precision up to five for arbitrary integrals over the three fundamental domains. Using a coordinate-free formulation, simple and rational procedures are developed to derive virtually all quadrature formulas, including some previously unpublished. Four symmetry groups of quadrature points are introduced to derive Gauss formulas, while their limiting forms are used to derive Lobatto formulas. Representative Gauss and Lobatto formulas are tabulated. The relative efficiency of their application to polyhedral and polygonal grids is detailed. The extension to higher degrees of precision is discussed.

  8. Semi-Lagrangian integration of a grid-point shallow water model on the sphere

    NASA Technical Reports Server (NTRS)

    Mcdonald, A.; Bates, J. R.

    1988-01-01

    This paper describes a semi-Lagrangian technique for integrating the equations of motion on the global domain. The technique uses an auxiliary spherical coordinate system at each near-polar gridpoint of the latitude-longitude grid; the auxiliary system is obtained by a rotation such that the new equator passes through the gridpoint in question and the new coordinate directions coincide with those of the original system at that point. The technique was applied to the shallow water equations, incorporating a semiimplicit treatment of the adjustment terms on a C-grid, with two-time levels. A five day integration was successfully carried out for a situation involving strong cross-polar flow. No filtering or diffusion was required to maintain stability over a five day period.

  9. Three-Phase Modular Cascaded H-Bridge Multilevel Inverter with Individual MPPT for Grid-Connected Photovoltaic Systems

    SciTech Connect

    Xiao, Bailu; Hang, Lijun; Riley, Cameron; Tolbert, Leon M; Ozpineci, Burak

    2013-01-01

    A three-phase modular cascaded H-bridge multilevel inverter for a grid-connected photovoltaic (PV) system is presented in this paper. To maximize the solar energy extraction of each PV string, an individual maximum power point tracking (MPPT) control scheme is applied, which allows the independent control of each dc-link voltage. PV mismatches may introduce unbalanced power supplied to the three-phase system. To solve this issue, a control scheme with modulation compensation is proposed. The three-phase modular cascaded multilevel inverter prototype has been built. Each H-bridge is connected to a 185 W solar panel. Simulation and experimental results are presented to validate the proposed ideas.

  10. Modeling, control, and simulation of grid connected intelligent hybrid battery/photovoltaic system using new hybrid fuzzy-neural method.

    PubMed

    Rezvani, Alireza; Khalili, Abbas; Mazareie, Alireza; Gandomkar, Majid

    2016-07-01

    Nowadays, photovoltaic (PV) generation is growing increasingly fast as a renewable energy source. Nevertheless, the drawback of the PV system is its dependence on weather conditions. Therefore, battery energy storage (BES) can be considered to assist for a stable and reliable output from PV generation system for loads and improve the dynamic performance of the whole generation system in grid connected mode. In this paper, a novel topology of intelligent hybrid generation systems with PV and BES in a DC-coupled structure is presented. Each photovoltaic cell has a specific point named maximum power point on its operational curve (i.e. current-voltage or power-voltage curve) in which it can generate maximum power. Irradiance and temperature changes affect these operational curves. Therefore, the nonlinear characteristic of maximum power point to environment has caused to development of different maximum power point tracking techniques. In order to capture the maximum power point (MPP), a hybrid fuzzy-neural maximum power point tracking (MPPT) method is applied in the PV system. Obtained results represent the effectiveness and superiority of the proposed method, and the average tracking efficiency of the hybrid fuzzy-neural is incremented by approximately two percentage points in comparison to the conventional methods. It has the advantages of robustness, fast response and good performance. A detailed mathematical model and a control approach of a three-phase grid-connected intelligent hybrid system have been proposed using Matlab/Simulink. PMID:26961319

  11. A Technical, Economic, and Environmental Performance of Grid-Connected Hybrid (Photovoltaic-Wind) Power System in Algeria

    PubMed Central

    Saheb-Koussa, Djohra; Koussa, Mustapha; Said, Nourredine

    2013-01-01

    This paper studies the technical, economic, and environmental analysis of wind and photovoltaic power systems connected to a conventional grid. The main interest in such systems is on-site consumption of the produced energy, system hybridization, pooling of resources, and contribution to the environment protection. To ensure a better management of system energy, models have been used for determining the power that the constituting subsystems can deliver under specific weather conditions. Simulation is performed using MATLAB-SIMULINK. While, the economic and environmental study is performed using HOMER software. From an economic point of view, this allows to compare the financial constraints on each part of the system for the case of Adrar site which is located to the northern part of the south of Algeria. It also permits to optimally size and select the system presenting the best features on the basis of two parameters, that is, cost and effectiveness. From an environmental point of view, this study allows highlighting the role of renewable energy in reducing gas emissions related to greenhouse effects. In addition, through a set of sensitivity analysis, it is found that the wind speed has more effects on the environmental and economic performances of grid-connected hybrid (photovoltaic-wind) power systems. PMID:24489488

  12. SunEdison Photovoltaic Grid Integration Evaluation: Cooperative Research and Development Final Report, CRADA Number CRD-08-302

    SciTech Connect

    Kroposki, B.

    2012-09-01

    Under this Agreement, NREL will work with SunEdison to monitor and analyze the performance of photovoltaic (PV) systems as they relate to grid integration. Initially this project will examine the performance of PV systems with respect to evaluating the benefits and impacts on the electric power grid.

  13. Grid integration and smart grid implementation of emerging technologies in electric power systems through approximate dynamic programming

    NASA Astrophysics Data System (ADS)

    Xiao, Jingjie

    A key hurdle for implementing real-time pricing of electricity is a lack of consumers' responses. Solutions to overcome the hurdle include the energy management system that automatically optimizes household appliance usage such as plug-in hybrid electric vehicle charging (and discharging with vehicle-to-grid) via a two-way communication with the grid. Real-time pricing, combined with household automation devices, has a potential to accommodate an increasing penetration of plug-in hybrid electric vehicles. In addition, the intelligent energy controller on the consumer-side can help increase the utilization rate of the intermittent renewable resource, as the demand can be managed to match the output profile of renewables, thus making the intermittent resource such as wind and solar more economically competitive in the long run. One of the main goals of this dissertation is to present how real-time retail pricing, aided by control automation devices, can be integrated into the wholesale electricity market under various uncertainties through approximate dynamic programming. What distinguishes this study from the existing work in the literature is that whole- sale electricity prices are endogenously determined as we solve a system operator's economic dispatch problem on an hourly basis over the entire optimization horizon. This modeling and algorithm framework will allow a feedback loop between electricity prices and electricity consumption to be fully captured. While we are interested in a near-optimal solution using approximate dynamic programming; deterministic linear programming benchmarks are use to demonstrate the quality of our solutions. The other goal of the dissertation is to use this framework to provide numerical evidence to the debate on whether real-time pricing is superior than the current flat rate structure in terms of both economic and environmental impacts. For this purpose, the modeling and algorithm framework is tested on a large-scale test case

  14. Integration of Grid and Sensor Web for Flood Monitoring and Risk Assessment from Heterogeneous Data

    NASA Astrophysics Data System (ADS)

    Kussul, Nataliia; Skakun, Sergii; Shelestov, Andrii

    2013-04-01

    Over last decades we have witnessed the upward global trend in natural disaster occurrence. Hydrological and meteorological disasters such as floods are the main contributors to this pattern. In recent years flood management has shifted from protection against floods to managing the risks of floods (the European Flood risk directive). In order to enable operational flood monitoring and assessment of flood risk, it is required to provide an infrastructure with standardized interfaces and services. Grid and Sensor Web can meet these requirements. In this paper we present a general approach to flood monitoring and risk assessment based on heterogeneous geospatial data acquired from multiple sources. To enable operational flood risk assessment integration of Grid and Sensor Web approaches is proposed [1]. Grid represents a distributed environment that integrates heterogeneous computing and storage resources administrated by multiple organizations. SensorWeb is an emerging paradigm for integrating heterogeneous satellite and in situ sensors and data systems into a common informational infrastructure that produces products on demand. The basic Sensor Web functionality includes sensor discovery, triggering events by observed or predicted conditions, remote data access and processing capabilities to generate and deliver data products. Sensor Web is governed by the set of standards, called Sensor Web Enablement (SWE), developed by the Open Geospatial Consortium (OGC). Different practical issues regarding integration of Sensor Web with Grids are discussed in the study. We show how the Sensor Web can benefit from using Grids and vice versa. For example, Sensor Web services such as SOS, SPS and SAS can benefit from the integration with the Grid platform like Globus Toolkit. The proposed approach is implemented within the Sensor Web framework for flood monitoring and risk assessment, and a case-study of exploiting this framework, namely the Namibia SensorWeb Pilot Project, is

  15. NOAA’s Global Earth Observation - Integrated Data Environment (GEO-IDE) in Action: Integration of Gridded Datasets

    NASA Astrophysics Data System (ADS)

    McCulloch, L.; McDonald, K. R.; Hankin, S. C.; Habermann, T.

    2009-12-01

    The National Oceanic and Atmospheric Administration (NOAA) is making substantial progress in enhancing the ability of users to discover, access, and use the vast amount of environmental information that it collects, maintains, and stores. It has defined a Global Earth Observation - Integrated Data Environment (GEO-IDE) initiative to promote and enable the interoperability of its data management services and to ensure that they are compatible and aligned with interagency and international efforts that are underway (e.g. the Global Earth Observation System of Systems and the Integrated Ocean Observing System). As an example of GEO-IDE in action, NOAA is developing a prototype gridded dataset integration capability. The initial focus will be to develop a Thematic Realtime Environmental Distributed Data Services (THREDDS) catalog of NOAA’s gridded datasets (e.g. model outputs, satellite products, HF radar observations, etc.) that are currently available in netCDF-CF format and enable all services that are readily available including: Data Access Protocol, Open Geospatial Consortium’s Web Map Service and Web Coverage Service. A parallel activity will be to harvest, repair, and extend metadata for the datasets to improve the ability for users to discover and then make use of the datasets. Once the above steps have been completed the focus will be to work with other data providers to expand the holdings that are accessible via this mechanism. This effort attempts to demonstrate the effectiveness of focusing on a single structural data type (e.g. gridded data) as an approach to integration. This poster will provide an overview of this effort, the technologies and standards being utilized, and will highlight the potential benefits to both NOAA and its scientific user community.

  16. Strategies and Decision Support Systems for Integrating Variable Energy Resources in Control Centers for Reliable Grid Operations

    SciTech Connect

    Jones, Lawrence E.

    2011-11-01

    This report provides findings from the field regarding the best ways in which to guide operational strategies, business processes and control room tools to support the integration of renewable energy into electrical grids.

  17. Strategies and Decision Support Systems for Integrating Variable Energy Resources in Control Centers for Reliable Grid Operations. Executive Summary

    SciTech Connect

    Jones, Lawrence E.

    2011-11-01

    This is the executive summary for a report that provides findings from the field regarding the best ways in which to guide operational strategies, business processes and control room tools to support the integration of renewable energy into electrical grids.

  18. Real time hardware implementation of power converters for grid integration of distributed generation and STATCOM systems

    NASA Astrophysics Data System (ADS)

    Jaithwa, Ishan

    Deployment of smart grid technologies is accelerating. Smart grid enables bidirectional flows of energy and energy-related communications. The future electricity grid will look very different from today's power system. Large variable renewable energy sources will provide a greater portion of electricity, small DERs and energy storage systems will become more common, and utilities will operate many different kinds of energy efficiency. All of these changes will add complexity to the grid and require operators to be able to respond to fast dynamic changes to maintain system stability and security. This thesis investigates advanced control technology for grid integration of renewable energy sources and STATCOM systems by verifying them on real time hardware experiments using two different systems: d SPACE and OPAL RT. Three controls: conventional, direct vector control and the intelligent Neural network control were first simulated using Matlab to check the stability and safety of the system and were then implemented on real time hardware using the d SPACE and OPAL RT systems. The thesis then shows how dynamic-programming (DP) methods employed to train the neural networks are better than any other controllers where, an optimal control strategy is developed to ensure effective power delivery and to improve system stability. Through real time hardware implementation it is proved that the neural vector control approach produces the fastest response time, low overshoot, and, the best performance compared to the conventional standard vector control method and DCC vector control technique. Finally the entrepreneurial approach taken to drive the technologies from the lab to market via ORANGE ELECTRIC is discussed in brief.

  19. Modularized multilevel and z-source power converter as renewable energy interface for vehicle and grid-connected applications

    NASA Astrophysics Data System (ADS)

    Cao, Dong

    Due the energy crisis and increased oil price, renewable energy sources such as photovoltaic panel, wind turbine, or thermoelectric generation module, are used more and more widely for vehicle and grid-connected applications. However, the output of these renewable energy sources varies according to different solar radiation, wind speed, or temperature difference, a power converter interface is required for the vehicle or grid-connected applications. Thermoelectric generation (TEG) module as a renewable energy source for automotive industry is becoming very popular recently. Because of the inherent characteristics of TEG modules, a low input voltage, high input current and high voltage gain dc-dc converters are needed for the automotive load. Traditional high voltage gain dc-dc converters are not suitable for automotive application in terms of size and high temperature operation. Switched-capacitor dc-dc converters have to be used for this application. However, high voltage spike and EMI problems exist in traditional switched-capacitor dc-dc converters. Huge capacitor banks have to be utilized to reduce the voltage ripple and achieve high efficiency. A series of zero current switching (ZCS) or zero voltage switching switched-capacitor dc-dc converters have been proposed to overcome the aforementioned problems of the traditional switched-capacitor dc-dc converters. By using the proposed soft-switching strategy, high voltage spike is reduced, high EMI noise is restricted, and the huge capacitor bank is eliminated. High efficiency, high power density and high temperature switched-capacitor dc-dc converters could be made for the TEG interface in vehicle applications. Several prototypes have been made to validate the proposed circuit and confirm the circuit operation. In order to apply PV panel for grid-connected application, a low cost dc-ac inverter interface is required. From the use of transformer and safety concern, two different solutions can be implemented, non

  20. MAGNETIC GRID

    DOEpatents

    Post, R.F.

    1960-08-01

    An electronic grid is designed employing magnetic forces for controlling the passage of charged particles. The grid is particularly applicable to use in gas-filled tubes such as ignitrons. thyratrons, etc., since the magnetic grid action is impartial to the polarity of the charged particles and, accordingly. the sheath effects encountered with electrostatic grids are not present. The grid comprises a conductor having sections spaced apart and extending in substantially opposite directions in the same plane, the ends of the conductor being adapted for connection to a current source.

  1. Coupling procedure modification improves sealing integrity of API connections

    SciTech Connect

    Chelette, K.D.; Bollfrass, C.A.

    1983-04-04

    This paper presents and recommends a pipe coupling procedure which provides several new options for improving the pressure sealing integrity of APILTC and Buttress casing connections. The combination of close tolerance control of taper and multiple tapers along the coupling thread length will ensure proper thread engagement and interference to produce the necessary surface contact pressures to seal and rate the coupling at the API pipe body internal yield pressure without the increased coupling OD values that will otherwise be required. The taper control of the first few threads of the coupling together with the steeper taper in the region of the pipe end, power-tight position ensures that sealing will occur at the extremes of the engaged thread length. This will exclude well bore pressures from the threaded region, thus reducing a tendency for jumpout at tensile loads less than the rated tensile failure load. The close taper tolerances and steeper taper section of the coupling will introduce a new capability to control the location of the final assembly position of the pipe in the coupling, providing for positive positional control of assembly without turn measure equipment.

  2. Modeling Framework and Validation of a Smart Grid and Demand Response System for Wind Power Integration

    SciTech Connect

    Broeer, Torsten; Fuller, Jason C.; Tuffner, Francis K.; Chassin, David P.; Djilali, Ned

    2014-01-31

    Electricity generation from wind power and other renewable energy sources is increasing, and their variability introduces new challenges to the power system. The emergence of smart grid technologies in recent years has seen a paradigm shift in redefining the electrical system of the future, in which controlled response of the demand side is used to balance fluctuations and intermittencies from the generation side. This paper presents a modeling framework for an integrated electricity system where loads become an additional resource. The agent-based model represents a smart grid power system integrating generators, transmission, distribution, loads and market. The model incorporates generator and load controllers, allowing suppliers and demanders to bid into a Real-Time Pricing (RTP) electricity market. The modeling framework is applied to represent a physical demonstration project conducted on the Olympic Peninsula, Washington, USA, and validation simulations are performed using actual dynamic data. Wind power is then introduced into the power generation mix illustrating the potential of demand response to mitigate the impact of wind power variability, primarily through thermostatically controlled loads. The results also indicate that effective implementation of Demand Response (DR) to assist integration of variable renewable energy resources requires a diversity of loads to ensure functionality of the overall system.

  3. Connecting Renewables Directly to the Grid: Resilient Multi-Terminal HVDC Networks with High-Voltage High-Frequency Electronics

    SciTech Connect

    2012-01-23

    GENI Project: GE is developing electricity transmission hardware that could connect distributed renewable energy sources, like wind farms, directly to the grid—eliminating the need to feed the energy generated through intermediate power conversion stations before they enter the grid. GE is using the advanced semiconductor material silicon carbide (SiC) to conduct electricity through its transmission hardware because SiC can operate at higher voltage levels than semiconductors made out of other materials. This high-voltage capability is important because electricity must be converted to high-voltage levels before it can be sent along the grid’s network of transmission lines. Power companies do this because less electricity is lost along the lines when the voltage is high.

  4. Applying the min-projection strategy to improve the transient performance of the three-phase grid-connected inverter.

    PubMed

    Baygi, Mahdi Oloumi; Ghazi, Reza; Monfared, Mohammad

    2014-07-01

    Applying the min-projection strategy (MPS) to a three-phase grid-connected inverter to improve its transient performance is the main objective of this paper. For this purpose, the inverter is first modeled as a switched linear system. Then, the feasibility of the MPS technique is investigated and the stability criterion is derived. Hereafter, the fundamental equations of the MPS for the control of the inverter are obtained. The proposed scheme is simulated in PSCAD/EMTDC environment. The validity of the MPS approach is confirmed by comparing the obtained results with those of VOC method. The results demonstrate that the proposed method despite its simplicity provides an excellent transient performance, fully decoupled control of active and reactive powers, acceptable THD level and a reasonable switching frequency. PMID:24929629

  5. A novel multi-model neuro-fuzzy-based MPPT for three-phase grid-connected photovoltaic system

    SciTech Connect

    Chaouachi, Aymen; Kamel, Rashad M.; Nagasaka, Ken

    2010-12-15

    This paper presents a novel methodology for Maximum Power Point Tracking (MPPT) of a grid-connected 20 kW photovoltaic (PV) system using neuro-fuzzy network. The proposed method predicts the reference PV voltage guarantying optimal power transfer between the PV generator and the main utility grid. The neuro-fuzzy network is composed of a fuzzy rule-based classifier and three multi-layered feed forwarded Artificial Neural Networks (ANN). Inputs of the network (irradiance and temperature) are classified before they are fed into the appropriated ANN for either training or estimation process while the output is the reference voltage. The main advantage of the proposed methodology, comparing to a conventional single neural network-based approach, is the distinct generalization ability regarding to the nonlinear and dynamic behavior of a PV generator. In fact, the neuro-fuzzy network is a neural network based multi-model machine learning that defines a set of local models emulating the complex and nonlinear behavior of a PV generator under a wide range of operating conditions. Simulation results under several rapid irradiance variations proved that the proposed MPPT method fulfilled the highest efficiency comparing to a conventional single neural network and the Perturb and Observe (P and O) algorithm dispositive. (author)

  6. Improved direct torque control of an induction generator used in a wind conversion system connected to the grid.

    PubMed

    Abdelli, Radia; Rekioua, Djamila; Rekioua, Toufik; Tounzi, Abdelmounaïm

    2013-07-01

    This paper presents a modulated hysteresis direct torque control (MHDTC) applied to an induction generator (IG) used in wind energy conversion systems (WECs) connected to the electrical grid through a back-to-back converter. The principle of this strategy consists in superposing to the torque reference a triangular signal, as in the PWM strategy, with the desired switching frequency. This new modulated reference is compared to the estimated torque by using a hysteresis controller as in the classical direct torque control (DTC). The aim of this new approach is to lead to a constant frequency and low THD in grid current with a unit power factor and a minimum voltage variation despite the wind variation. To highlight the effectiveness of the proposed method, a comparison was made with classical DTC and field oriented control method (FOC). The obtained simulation results, with a variable wind profile, show an adequate dynamic of the conversion system using the proposed method compared to the classical approaches. PMID:23615169

  7. A Vector Control for Grid-connected Wind Power Generation with Doubly Fed Induction Generator

    NASA Astrophysics Data System (ADS)

    Kai, Takaaki; Tanaka, Yuji; Kaneda, Hirotoshi; Kobayashi, Daichi; Tanaka, Akio

    Recently, doubly fed induction generator (DFIG) and synchronous generator are mostly applied for wind power generation due to high efficiently for wind energy capture. An inverter system is required to control wind turbine speed and power factor in those generators. The inverter rating of the synchronous generator equals to generator rating. However, DFIG has the advantage that the inverter rating is about 25% to the generator rating. The paper describes a vector control of DFIG inter-connected to power line. The performance of proposed vector control is examined using power system simulation software PSCAD/EMTDC for the DFIG inter-connected to 6.6kv distribution line. The results show good dynamic responses and high accuracy to the stator active power control and the stator reactive power control.

  8. A feasibility study of stationary and dual-axis tracking grid-connected photovoltaic systems in the Upper Midwest

    NASA Astrophysics Data System (ADS)

    Warren, Ryan Duwain

    Three primary objectives were defined for this work. The first objective was to determine, assess, and compare the performance, heat transfer characteristics, economics, and feasibility of real-world stationary and dual-axis tracking grid-connected photovoltaic (PV) systems in the Upper Midwest. This objective was achieved by installing two grid-connected PV systems with different mounting schemes in central Iowa, implementing extensive data acquisition systems, monitoring operation of the PV systems for one full year, and performing detailed experimental performance and economic studies. The two PV systems that were installed, monitored, and analyzed included a 4.59 kWp roof-mounted stationary system oriented for maximum annual energy production, and a 1.02 kWp pole-mounted actively controlled dual-axis tracking system. The second objective was to demonstrate the actual use and performance of real-world stationary and dual-axis tracking grid-connected PV systems used for building energy generation applications. This objective was achieved by offering the installed PV systems to the public for demonstration purposes and through the development of three computer-based tools: a software interface that has the ability to display real-time and historical performance and meteorological data of both systems side-by-side, a software interface that shows real-time and historical video and photographs of each system, and a calculator that can predict performance and economics of stationary and dual-axis tracking grid-connected PV systems at various locations in the United States. The final objective was to disseminate this work to social, professional, scientific, and academic communities in a way that is applicable, objective, accurate, accessible, and comprehensible. This final objective will be addressed by publishing the results of this work and making the computer-based tools available on a public website (www.energy.iastate.edu/Renewable/solar). Detailed experimental

  9. Power fluctuation reduction methodology for the grid-connected renewable power systems

    NASA Astrophysics Data System (ADS)

    Aula, Fadhil T.; Lee, Samuel C.

    2013-04-01

    This paper presents a new methodology for eliminating the influence of the power fluctuations of the renewable power systems. The renewable energy, which is to be considered an uncertain and uncontrollable resource, can only provide irregular electrical power to the power grid. This irregularity creates fluctuations of the generated power from the renewable power systems. These fluctuations cause instability to the power system and influence the operation of conventional power plants. Overall, the power system is vulnerable to collapse if necessary actions are not taken to reduce the impact of these fluctuations. This methodology aims at reducing these fluctuations and makes the generated power capability for covering the power consumption. This requires a prediction tool for estimating the generated power in advance to provide the range and the time of occurrence of the fluctuations. Since most of the renewable energies are weather based, as a result a weather forecast technique will be used for predicting the generated power. The reduction of the fluctuation also requires stabilizing facilities to maintain the output power at a desired level. In this study, a wind farm and a photovoltaic array as renewable power systems and a pumped-storage and batteries as stabilizing facilities are used, since they are best suitable for compensating the fluctuations of these types of power suppliers. As an illustrative example, a model of wind and photovoltaic power systems with battery energy and pumped hydro storage facilities for power fluctuation reduction is included, and its power fluctuation reduction is verified through simulation.

  10. System efficiency of a tap transformer based grid connection topology applied on a direct driven generator for wind power.

    PubMed

    Apelfröjd, Senad; Eriksson, Sandra

    2014-01-01

    Results from experiments on a tap transformer based grid connection system for a variable speed vertical axis wind turbine are presented. The tap transformer based system topology consists of a passive diode rectifier, DC-link, IGBT inverter, LCL-filter, and tap transformer. Full range variable speed operation is enabled by using the different step-up ratios of a tap transformer. Simulations using MATLAB/Simulink have been performed in order to study the behavior of the system. A full experimental set up of the system has been used in the laboratory study, where a clone of the on-site generator was driven by an induction motor and the system was connected to a resistive load to better evaluate the performance. Furthermore, the system is run and evaluated for realistic wind speeds and variable speed operation. For a more complete picture of the system performance, a case study using real site Weibull parameters is done, comparing different tap selection options. The results show high system efficiency at nominal power and an increase in overall power output for full tap operation in comparison with the base case, a standard transformer. In addition, the loss distribution at different wind speeds is shown, which highlights the dominant losses at low and high wind speeds. Finally, means for further increasing the overall system efficiency are proposed. PMID:25258733

  11. System Efficiency of a Tap Transformer Based Grid Connection Topology Applied on a Direct Driven Generator for Wind Power

    PubMed Central

    2014-01-01

    Results from experiments on a tap transformer based grid connection system for a variable speed vertical axis wind turbine are presented. The tap transformer based system topology consists of a passive diode rectifier, DC-link, IGBT inverter, LCL-filter, and tap transformer. Full range variable speed operation is enabled by using the different step-up ratios of a tap transformer. Simulations using MATLAB/Simulink have been performed in order to study the behavior of the system. A full experimental set up of the system has been used in the laboratory study, where a clone of the on-site generator was driven by an induction motor and the system was connected to a resistive load to better evaluate the performance. Furthermore, the system is run and evaluated for realistic wind speeds and variable speed operation. For a more complete picture of the system performance, a case study using real site Weibull parameters is done, comparing different tap selection options. The results show high system efficiency at nominal power and an increase in overall power output for full tap operation in comparison with the base case, a standard transformer. In addition, the loss distribution at different wind speeds is shown, which highlights the dominant losses at low and high wind speeds. Finally, means for further increasing the overall system efficiency are proposed. PMID:25258733

  12. Integration of a neuroimaging processing pipeline into a pan-canadian computing grid

    NASA Astrophysics Data System (ADS)

    Lavoie-Courchesne, S.; Rioux, P.; Chouinard-Decorte, F.; Sherif, T.; Rousseau, M.-E.; Das, S.; Adalat, R.; Doyon, J.; Craddock, C.; Margulies, D.; Chu, C.; Lyttelton, O.; Evans, A. C.; Bellec, P.

    2012-02-01

    The ethos of the neuroimaging field is quickly moving towards the open sharing of resources, including both imaging databases and processing tools. As a neuroimaging database represents a large volume of datasets and as neuroimaging processing pipelines are composed of heterogeneous, computationally intensive tools, such open sharing raises specific computational challenges. This motivates the design of novel dedicated computing infrastructures. This paper describes an interface between PSOM, a code-oriented pipeline development framework, and CBRAIN, a web-oriented platform for grid computing. This interface was used to integrate a PSOM-compliant pipeline for preprocessing of structural and functional magnetic resonance imaging into CBRAIN. We further tested the capacity of our infrastructure to handle a real large-scale project. A neuroimaging database including close to 1000 subjects was preprocessed using our interface and publicly released to help the participants of the ADHD-200 international competition. This successful experiment demonstrated that our integrated grid-computing platform is a powerful solution for high-throughput pipeline analysis in the field of neuroimaging.

  13. Building-to-Grid Integration through Commercial Building Portfolios Participating in Energy and Frequency Regulation Markets

    NASA Astrophysics Data System (ADS)

    Pavlak, Gregory S.

    Building energy use is a significant contributing factor to growing worldwide energy demands. In pursuit of a sustainable energy future, commercial building operations must be intelligently integrated with the electric system to increase efficiency and enable renewable generation. Toward this end, a model-based methodology was developed to estimate the capability of commercial buildings to participate in frequency regulation ancillary service markets. This methodology was integrated into a supervisory model predictive controller to optimize building operation in consideration of energy prices, demand charges, and ancillary service revenue. The supervisory control problem was extended to building portfolios to evaluate opportunities for synergistic effect among multiple, centrally-optimized buildings. Simulation studies performed showed that the multi-market optimization was able to determine appropriate opportunities for buildings to provide frequency regulation. Total savings were increased by up to thirteen percentage points, depending on the simulation case. Furthermore, optimizing buildings as a portfolio achieved up to seven additional percentage points of savings, depending on the case. Enhanced energy and cost savings opportunities were observed by taking the novel perspective of optimizing building portfolios in multiple grid markets, motivating future pursuits of advanced control paradigms that enable a more intelligent electric grid.

  14. Quantifiably secure power grid operation, management, and evolution : a study of uncertainties affecting the grid integration of renewables.

    SciTech Connect

    Gray, Genetha Anne; Watson, Jean-Paul; Silva Monroy, Cesar Augusto; Gramacy, Robert B.

    2013-09-01

    This report summarizes findings and results of the Quantifiably Secure Power Grid Operation, Management, and Evolution LDRD. The focus of the LDRD was to develop decisionsupport technologies to enable rational and quantifiable risk management for two key grid operational timescales: scheduling (day-ahead) and planning (month-to-year-ahead). Risk or resiliency metrics are foundational in this effort. The 2003 Northeast Blackout investigative report stressed the criticality of enforceable metrics for system resiliency - the grid's ability to satisfy demands subject to perturbation. However, we neither have well-defined risk metrics for addressing the pervasive uncertainties in a renewable energy era, nor decision-support tools for their enforcement, which severely impacts efforts to rationally improve grid security. For day-ahead unit commitment, decision-support tools must account for topological security constraints, loss-of-load (economic) costs, and supply and demand variability - especially given high renewables penetration. For long-term planning, transmission and generation expansion must ensure realized demand is satisfied for various projected technological, climate, and growth scenarios. The decision-support tools investigated in this project paid particular attention to tailoriented risk metrics for explicitly addressing high-consequence events. Historically, decisionsupport tools for the grid consider expected cost minimization, largely ignoring risk and instead penalizing loss-of-load through artificial parameters. The technical focus of this work was the development of scalable solvers for enforcing risk metrics. Advanced stochastic programming solvers were developed to address generation and transmission expansion and unit commitment, minimizing cost subject to pre-specified risk thresholds. Particular attention was paid to renewables where security critically depends on production and demand prediction accuracy. To address this concern, powerful

  15. Integrating Solar Power onto the Electric Grid - Bridging the Gap between Atmospheric Science, Engineering and Economics

    NASA Astrophysics Data System (ADS)

    Ghonima, M. S.; Yang, H.; Zhong, X.; Ozge, B.; Sahu, D. K.; Kim, C. K.; Babacan, O.; Hanna, R.; Kurtz, B.; Mejia, F. A.; Nguyen, A.; Urquhart, B.; Chow, C. W.; Mathiesen, P.; Bosch, J.; Wang, G.

    2015-12-01

    One of the main obstacles to high penetrations of solar power is the variable nature of solar power generation. To mitigate variability, grid operators have to schedule additional reliability resources, at considerable expense, to ensure that load requirements are met by generation. Thus despite the cost of solar PV decreasing, the cost of integrating solar power will increase as penetration of solar resources onto the electric grid increases. There are three principal tools currently available to mitigate variability impacts: (i) flexible generation, (ii) storage, either virtual (demand response) or physical devices and (iii) solar forecasting. Storage devices are a powerful tool capable of ensuring smooth power output from renewable resources. However, the high cost of storage is prohibitive and markets are still being designed to leverage their full potential and mitigate their limitation (e.g. empty storage). Solar forecasting provides valuable information on the daily net load profile and upcoming ramps (increasing or decreasing solar power output) thereby providing the grid advance warning to schedule ancillary generation more accurately, or curtail solar power output. In order to develop solar forecasting as a tool that can be utilized by the grid operators we identified two focus areas: (i) develop solar forecast technology and improve solar forecast accuracy and (ii) develop forecasts that can be incorporated within existing grid planning and operation infrastructure. The first issue required atmospheric science and engineering research, while the second required detailed knowledge of energy markets, and power engineering. Motivated by this background we will emphasize area (i) in this talk and provide an overview of recent advancements in solar forecasting especially in two areas: (a) Numerical modeling tools for coastal stratocumulus to improve scheduling in the day-ahead California energy market. (b) Development of a sky imager to provide short term

  16. Power Smoothing and MPPT for Grid-connected Wind Power Generation with Doubly Fed Induction Generator

    NASA Astrophysics Data System (ADS)

    Kai, Takaaki; Tanaka, Yuji; Kaneda, Hirotoshi; Kobayashi, Daichi; Tanaka, Akio

    Recently, doubly fed induction generator (DFIG) and synchronous generator are mostly applied for wind power generation, and variable speed control and power factor control are executed for high efficiently for wind energy capture and high quality for power system voltage. In variable speed control, a wind speed or a generator speed is used for maximum power point tracking. However, performances of a wind generation power fluctuation due to wind speed variation have not yet investigated for those controls. The authors discuss power smoothing by those controls for the DFIG inter-connected to 6.6kV distribution line. The performances are verified using power system simulation software PSCAD/EMTDC for actual wind speed data and are examined from an approximate equation of wind generation power fluctuation for wind speed variation.

  17. Sodium-Beta Batteries for Grid-Scale Storage: Planar Sodium-Beta Batteries for Renewable Integration and Grid Applications

    SciTech Connect

    2010-02-01

    Broad Funding Opportunity Announcement Project: EaglePicher is developing a sodium-beta alumina (Na-Beta) battery for grid-scale energy storage. High-temperature Na-Beta batteries are a promising grid-scale energy storage technology, but existing approaches are expensive and unreliable. EaglePicher has modified the shape of the traditional, tubular-shaped Na-Beta battery. It is using an inexpensive stacked design to improve performance at lower temperatures, leading to a less expensive overall storage technology. The new design greatly simplifies the manufacturing process for beta alumina membranes (a key enabling technology), providing a subsequent pathway to the production of scalable, modular batteries at half the cost of the existing tubular designs.

  18. Fuzzy Logic Based Controller for a Grid-Connected Solid Oxide Fuel Cell Power Plant.

    PubMed

    Chatterjee, Kalyan; Shankar, Ravi; Kumar, Amit

    2014-10-01

    This paper describes a mathematical model of a solid oxide fuel cell (SOFC) power plant integrated in a multimachine power system. The utilization factor of a fuel stack maintains steady state by tuning the fuel valve in the fuel processor at a rate proportional to a current drawn from the fuel stack. A suitable fuzzy logic control is used for the overall system, its objective being controlling the current drawn by the power conditioning unit and meet a desirable output power demand. The proposed control scheme is verified through computer simulations. PMID:25053926

  19. Using graph approach for managing connectivity in integrative landscape modelling

    NASA Astrophysics Data System (ADS)

    Rabotin, Michael; Fabre, Jean-Christophe; Libres, Aline; Lagacherie, Philippe; Crevoisier, David; Moussa, Roger

    2013-04-01

    In cultivated landscapes, a lot of landscape elements such as field boundaries, ditches or banks strongly impact water flows, mass and energy fluxes. At the watershed scale, these impacts are strongly conditionned by the connectivity of these landscape elements. An accurate representation of these elements and of their complex spatial arrangements is therefore of great importance for modelling and predicting these impacts.We developped in the framework of the OpenFLUID platform (Software Environment for Modelling Fluxes in Landscapes) a digital landscape representation that takes into account the spatial variabilities and connectivities of diverse landscape elements through the application of the graph theory concepts. The proposed landscape representation consider spatial units connected together to represent the flux exchanges or any other information exchanges. Each spatial unit of the landscape is represented as a node of a graph and relations between units as graph connections. The connections are of two types - parent-child connection and up/downstream connection - which allows OpenFLUID to handle hierarchical graphs. Connections can also carry informations and graph evolution during simulation is possible (connections or elements modifications). This graph approach allows a better genericity on landscape representation, a management of complex connections and facilitate development of new landscape representation algorithms. Graph management is fully operational in OpenFLUID for developers or modelers ; and several graph tools are available such as graph traversal algorithms or graph displays. Graph representation can be managed i) manually by the user (for example in simple catchments) through XML-based files in easily editable and readable format or ii) by using methods of the OpenFLUID-landr library which is an OpenFLUID library relying on common open-source spatial libraries (ogr vector, geos topologic vector and gdal raster libraries). Open

  20. The Development of a Smart Distribution Grid Testbed for Integrated Information Management Systems

    SciTech Connect

    Lu, Ning; Du, Pengwei; Paulson, Patrick R.; Greitzer, Frank L.; Guo, Xinxin; Hadley, Mark D.

    2011-01-31

    This paper presents a smart distribution grid testbed to test or compare designs of integrated information management systems (I2MSs). An I2MS extracts and synthesizes information from a wide range of data sources to detect abnormal system behaviors, identify possible causes, assess the system status, and provide grid operators with response suggestions. The objective of the testbed is to provide a modeling environment with sufficient data sources for the I2MS design. The testbed includes five information layers and a physical layer; it generates multi-layer chronological data based on actual measurement playbacks or simulated data sets produced by the physical layer. The testbed models random hardware failures, human errors, extreme weather events, and deliberate tampering attempts to allow users to evaluate the performance of different I2MS designs. Initial results of I2MS performance tests showed that the testbed created a close-to-real-world environment that allowed key performance metrics of the I2MS to be evaluated

  1. The Development of a Smart Distribution Grid Testbed for Integrated Information Management Systems

    SciTech Connect

    Lu, Ning; Du, Pengwei; Paulson, Patrick R.; Greitzer, Frank L.; Guo, Xinxin; Hadley, Mark D.

    2011-07-28

    This paper presents a smart distribution grid testbed to test or compare designs of integrated information management systems (I2MSs). An I2MS extracts and synthesizes information from a wide range of data sources to detect abnormal system behaviors, identify possible causes, assess the system status, and provide grid operators with response suggestions. The objective of the testbed is to provide a modeling environment with sufficient data sources for the I2MS design. The testbed includes five information layers and a physical layer; it generates multi-layer chronological data based on actual measurement playbacks or simulated data sets produced by the physical layer. The testbed models random hardware failures, human errors, extreme weather events, and deliberate tampering attempts to allow users to evaluate the performance of different I2MS designs. Initial results of I2MS performance tests showed that the testbed created a close-to-real-world environment that allowed key performance metrics of the I2MS to be evaluated.

  2. Arts Integration: An Exploration of the Dis/Connect between Policy and Live(d) Practice

    ERIC Educational Resources Information Center

    LaJevic, Lisa M.

    2009-01-01

    This dissertation explores the dis/connect between arts integration policy (i.e. written texts and curriculum documents) and the live(d) practice of teachers working with arts integration. Although previous studies have examined how arts integration is implemented in schools and how it affects student achievement, particularly standardized test…

  3. GAP analysis towards a design qualification standard development for grid-connected photovoltaic inverters.

    SciTech Connect

    Tamizhmani, Govindasamy; Granata, Jennifer E.; Maracas, George; Ayyanar, Raja; Marinella, Matthew; Venkataramanan, Sai Balasubramanian Alampoondi

    2011-06-01

    A dedicated design qualification standard for PV inverters does not exist. Development of a well-accepted design qualification standard, specifically for PV inverters will significantly improve the reliability and performance of inverters. The existing standards for PV inverters such as ANSI/UL 1741 and IEC 62109-1 primarily focus on safety of PV inverters. The IEC 62093 discusses inverter qualification but it includes all the BOS components. There are other general standards for distributed generators including the IEEE 1547 series of standards which cover major concerns like utility integration but they are not dedicated to PV inverters and are not written from a design qualification point of view. In this paper some of the potential requirements for a design qualification standard for PV inverters are addressed. The missing links in existing PV inverter related standards are identified and with the IEC 62093 as a guideline, the possible inclusions in the framework for a dedicated design qualification standard of PV inverter are discussed. Some of the key missing links are related to electric stress tests. Hence, a method to adapt the existing surge withstand test standards for use in design qualification standard of PV inverter is presented.

  4. Validation Study of the Integral-Differential Scheme for Multi-Block Grids

    NASA Astrophysics Data System (ADS)

    Mrema, Honest Frank

    This MS Thesis seeks to validate the accuracy of the Integral-Differential Scheme (IDS). In the attempts to accomplish this task, research efforts were focused on the scheme's ability to capture the physics of known flow fields, as well as the scheme's ability to predict the features of flow field quantities that may be derived from experimental measurements. The IDS was developed with the goal of being computationally efficient, from a programming perspective, as well as being numerically accurate, stable, and robust, from a mathematical perspective. The IDS is designed to solve the full Navier-Stokes equations in their integral forms. Unlike traditional control volume schemes, the IDS is built upon two sets of cells: spatial and temporal cells. For 2-D flows, the IDS considers an elementary control volume as a collection of four spatial cells and a single temporal cell. Similar to other explicit CFD schemes, the IDS relies on the use of the Taylor series expansion and other traditional CFD criteria. It is of interest to note that there are previous IDS validation studies which were conducted at North Carolina A&T State University. These past studies mainly focused on the qualitative aspects of the flow field physics. Furthermore, in all cases, they focused on flow field problems that can be represented by single-block grids. In this analysis, the validation studies are focused on multi-block grids in which the physics of the flow field is made complicated due to the presence of shock waves and flow separation zones. Of interest to this MS Thesis are two supersonic flow field problems that are supported by experimental data; namely, the supersonic flow over a rearward-facing step problem and the supersonic flow over a cavity problem. The validation studies conducted herein demonstrated that the IDS was able to predict the experimental data in both cases.

  5. WNoDeS, a tool for integrated Grid and Cloud access and computing farm virtualization

    NASA Astrophysics Data System (ADS)

    Salomoni, Davide; Italiano, Alessandro; Ronchieri, Elisabetta

    2011-12-01

    INFN CNAF is the National Computing Center, located in Bologna, Italy, of the Italian National Institute for Nuclear Physics (INFN). INFN CNAF, also called the INFN Tier-1, provides computing and storage facilities to the International High-Energy Physics community and to several multi-disciplinary experiments. Currently, the INFN Tier-1 supports more than twenty different collaborations; in this context, optimization of the usage of computing resources is essential. This is one of the main drivers behind the development of a software called WNoDeS (Worker Nodes on Demand Service). WNoDeS, developed at INFN CNAF and deployed on the INFN Tier-1 production infrastructure, is a solution to virtualize computing resources and to make them available through local, Grid or Cloud interfaces. It is designed to be fully integrated with a Local Resource Management System; it is therefore inherently scalable and permits full integration with existing scheduling, policing, monitoring, accounting and security workflows. WNoDeS dynamically instantiates Virtual Machines (VMs) on-demand, i.e. only when the need arises; these VMs can be tailored and used for purposes like batch job execution, interactive analysis or service instantiation. WNoDeS supports interaction with user requests through traditional batch or Grid jobs and also via the Open Cloud Computing Interface standard, making it possible to allocate compute, storage and network resources on a pay-as-you-go basis. User authentication is supported via several authentication methods, while authorization policies are handled via gLite Argus. WNoDeS is an ambitious solution aimed at virtualizing cluster resources in medium or large scale computing centers, with up to several thousands of Virtual Machines up and running at any given time. In this paper, we descrive the WNoDeS architecture.

  6. Integration of external metadata into the Earth System Grid Federation (ESGF)

    NASA Astrophysics Data System (ADS)

    Berger, Katharina; Levavasseur, Guillaume; Stockhause, Martina; Lautenschlager, Michael

    2015-04-01

    International projects with high volume data usually disseminate their data in a federated data infrastructure, e.g.~the Earth System Grid Federation (ESGF). The ESGF aims to make the geographically distributed data seamlessly discoverable and accessible. Additional data-related information is currently collected and stored in separate repositories by each data provider. This scattered and useful information is not or only partly available for ESGF users. Examples for such additional information systems are ES-DOC/metafor for model and simulation information, IPSL's versioning information, CHARMe for user annotations, DKRZ's quality information and data citation information. The ESGF Quality Control working team (esgf-qcwt) aims to integrate these valuable pieces of additional information into the ESGF in order to make them available to users and data archive managers by (i) integrating external information into ESGF portal, (ii) integrating links to external information objects into the ESGF metadata index, e.g. by the use of PIDs (Persistent IDentifiers), and (iii) automating the collection of external information during the ESGF data publication process. For the sixth phase of CMIP (Coupled Model Intercomparison Project), the ESGF metadata index is to be enriched by additional information on data citation, file version, etc. This information will support users directly and can be automatically exploited by higher level services (human and machine readability).

  7. Connecting Distributed Energy Resources to the Grid: Their Benefits to the DER Owner etc.

    SciTech Connect

    Poore, WP

    2003-07-09

    The vision of the Distributed Energy Research Program (DER) program of the U.S. Department of Energy (DOE) is that the United States will have the cleanest and most efficient and reliable energy system in the world by maximizing the use of affordable distributed energy resources. Electricity consumers will be able to choose from a diverse number of efficient, cost-effective, and environmentally friendly distributed energy options and easily connect them into the nation's energy infrastructure while providing benefits to their owners and other stakeholders. The long-term goal of this vision is that DER will achieve a 20% share of new electric capacity additions in the United States by 2010, thereby helping to make the nation's electric power generation and delivery system more efficient, reliable, secure, clean, economical, and diverse in terms of fuel use (oil, natural gas, solar, hydroelectric, etc.) and prime mover resource (solar, wind, gas turbines, etc.). Near- and mid-term goals are to develop new technologies for implementing and operating DER and address barriers associated with DER usage and then to reduce costs and emissions and improve the efficiency and reliability of DER. Numerous strategies for meeting these goals have been developed into a research, development, and demonstration (RD&D) program that supports generation and delivery systems architecture, including modeling and simulation tools. The benefits associated with DER installations are often significant and numerous. They almost always provide tangible economic benefits, such as energy savings or transmission and distribution upgrade deferrals, as well as intangible benefits, such as power quality improvements that lengthen maintenance or repair intervals for power equipment. Also, the benefits routinely are dispersed among end users, utilities, and the public. For instance, an end user may use the DER to reduce their peak demand and save money due to lower demand charges. Reduced end user

  8. Training Recurrent Neural Networks With the Levenberg-Marquardt Algorithm for Optimal Control of a Grid-Connected Converter.

    PubMed

    Fu, Xingang; Li, Shuhui; Fairbank, Michael; Wunsch, Donald C; Alonso, Eduardo

    2015-09-01

    This paper investigates how to train a recurrent neural network (RNN) using the Levenberg-Marquardt (LM) algorithm as well as how to implement optimal control of a grid-connected converter (GCC) using an RNN. To successfully and efficiently train an RNN using the LM algorithm, a new forward accumulation through time (FATT) algorithm is proposed to calculate the Jacobian matrix required by the LM algorithm. This paper explores how to incorporate FATT into the LM algorithm. The results show that the combination of the LM and FATT algorithms trains RNNs better than the conventional backpropagation through time algorithm. This paper presents an analytical study on the optimal control of GCCs, including theoretically ideal optimal and suboptimal controllers. To overcome the inapplicability of the optimal GCC controller under practical conditions, a new RNN controller with an improved input structure is proposed to approximate the ideal optimal controller. The performance of an ideal optimal controller and a well-trained RNN controller was compared in close to real-life power converter switching environments, demonstrating that the proposed RNN controller can achieve close to ideal optimal control performance even under low sampling rate conditions. The excellent performance of the proposed RNN controller under challenging and distorted system conditions further indicates the feasibility of using an RNN to approximate optimal control in practical applications. PMID:25330496

  9. The National Grid Project: A system overview

    NASA Technical Reports Server (NTRS)

    Gaither, Adam; Gaither, Kelly; Jean, Brian; Remotigue, Michael; Whitmire, John; Soni, Bharat; Thompson, Joe; Dannenhoffer,, John; Weatherill, Nigel

    1995-01-01

    The National Grid Project (NGP) is a comprehensive numerical grid generation software system that is being developed at the National Science Foundation (NSF) Engineering Research Center (ERC) for Computational Field Simulation (CFS) at Mississippi State University (MSU). NGP is supported by a coalition of U.S. industries and federal laboratories. The objective of the NGP is to significantly decrease the amount of time it takes to generate a numerical grid for complex geometries and to increase the quality of these grids to enable computational field simulations for applications in industry. A geometric configuration can be discretized into grids (or meshes) that have two fundamental forms: structured and unstructured. Structured grids are formed by intersecting curvilinear coordinate lines and are composed of quadrilateral (2D) and hexahedral (3D) logically rectangular cells. The connectivity of a structured grid provides for trivial identification of neighboring points by incrementing coordinate indices. Unstructured grids are composed of cells of any shape (commonly triangles, quadrilaterals, tetrahedra and hexahedra), but do not have trivial identification of neighbors by incrementing an index. For unstructured grids, a set of points and an associated connectivity table is generated to define unstructured cell shapes and neighboring points. Hybrid grids are a combination of structured grids and unstructured grids. Chimera (overset) grids are intersecting or overlapping structured grids. The NGP system currently provides a user interface that integrates both 2D and 3D structured and unstructured grid generation, a solid modeling topology data management system, an internal Computer Aided Design (CAD) system based on Non-Uniform Rational B-Splines (NURBS), a journaling language, and a grid/solution visualization system.

  10. Integration of permanent magnet synchronous generator wind turbines into power grid

    NASA Astrophysics Data System (ADS)

    Abedini, Asghar

    , integrating energy storage systems with wind farms has attracted a lot of attention. These two subjects are addressed in this dissertation in detail. Permanent Magnet Synchronous Generators (PMSG) are used in variable speed wind turbines. In this thesis, the dynamic of the PMSG is investigated and a power electronic converter is designed to integrate the wind turbine to the grid. The risks of PMSG wind turbines such as low voltage ride through and short circuits, are assessed and the methods of mitigating the risks are discussed. In the second section of the thesis, various methods of smoothing wind turbine output power are explained and compared. Two novel methods of output power smoothing are analyzed: Rotor inertia and Super capacitors. The advantages and disadvantages of each method are explained and the dynamic model of each method is developed. The performance of the system is evaluated by simulating the wind turbine system in each method. The concepts of the methods of smoothing wind power can be implemented in other types of wind turbines such as Doubly Fed Induction Generator (DFIG) wind turbines.

  11. Integration and Exposure of Large Scale Computational Resources Across the Earth System Grid Federation (ESGF)

    NASA Astrophysics Data System (ADS)

    Duffy, D.; Maxwell, T. P.; Doutriaux, C.; Williams, D. N.; Chaudhary, A.; Ames, S.

    2015-12-01

    As the size of remote sensing observations and model output data grows, the volume of the data has become overwhelming, even to many scientific experts. As societies are forced to better understand, mitigate, and adapt to climate changes, the combination of Earth observation data and global climate model projects is crucial to not only scientists but to policy makers, downstream applications, and even the public. Scientific progress on understanding climate is critically dependent on the availability of a reliable infrastructure that promotes data access, management, and provenance. The Earth System Grid Federation (ESGF) has created such an environment for the Intergovernmental Panel on Climate Change (IPCC). ESGF provides a federated global cyber infrastructure for data access and management of model outputs generated for the IPCC Assessment Reports (AR). The current generation of the ESGF federated grid allows consumers of the data to find and download data with limited capabilities for server-side processing. Since the amount of data for future AR is expected to grow dramatically, ESGF is working on integrating server-side analytics throughout the federation. The ESGF Compute Working Team (CWT) has created a Web Processing Service (WPS) Application Programming Interface (API) to enable access scalable computational resources. The API is the exposure point to high performance computing resources across the federation. Specifically, the API allows users to execute simple operations, such as maximum, minimum, average, and anomalies, on ESGF data without having to download the data. These operations are executed at the ESGF data node site with access to large amounts of parallel computing capabilities. This presentation will highlight the WPS API, its capabilities, provide implementation details, and discuss future developments.

  12. Empirical Analysis of the Variability of Wind Generation in India: Implications for Grid Integration

    SciTech Connect

    Phadke, Amol; Abhyankar, NIkit; Rao, Poorvi

    2014-06-17

    We analyze variability in load and wind generation in India to assess its implications for grid integration of large scale wind projects using actual wind generation and load data from two states in India, Karnataka and Tamil Nadu. We compare the largest variations in load and net load (load ?wind, i.e., load after integrating wind) that the generation fleet has to meet. In Tamil Nadu, where wind capacity is about 53percent of the peak demand, we find that the additional variation added due to wind over the current variation in load is modest; if wind penetration reaches 15percent and 30percent by energy, the additional hourly variation is less than 0.5percent and 4.5percent of the peak demand respectively for 99percent of the time. For wind penetration of 15percent by energy, Tamil Nadu system is found to be capable of meeting the additional ramping requirement for 98.8percent of the time. Potential higher uncertainty in net load compared to load is found to have limited impact on ramping capability requirements of the system if coal plants can me ramped down to 50percent of their capacity. Load and wind aggregation in Tamil Nadu and Karnataka is found to lower the variation by at least 20percent indicating the benefits geographic diversification. These findings suggest modest additional flexible capacity requirements and costs for absorbing variation in wind power and indicate that the potential capacity support (if wind does not generate enough during peak periods) may be the issue that has more bearing on the economics of integrating wind

  13. Making Training Connections: Integrating Workplace Education in Small Businesses.

    ERIC Educational Resources Information Center

    Lopez-Valadez, Jeanne; And Others

    This handbook is designed for individuals responsible for planning employee education, technical training, and other human resource development services in a workplace setting, especially in small business. It provides information on integrating basic education activities with technical training and organizational change activities to enable all…

  14. An Integration Of Subgrid Physics Into Coarse Grid Simulations Of River Models

    NASA Astrophysics Data System (ADS)

    Fu, S.; Hodges, B. R.

    2007-12-01

    In river flows, the large eddies scale on river width and depth, thus the uncertainties and inhomogeneities in river boundary structure have length scales only slightly smaller the large-eddy scale. Consequently, the turbulence generated by the river bottom inhomogeneity is hydrodynamically significant. Conventionally, uncertainty and inhomogeneity in large-scale river modeling are generally addressed together by calibrating a roughness coefficient. However, this kind of calibration is inherently grid dependent due to nonlinearity associated with local flow inhomogeneity. In other words, the work to calibrate a model at one grid scale is lost if the model grid is altered, and such grid-dependent calibration cannot provide insight into the unresolved processes or features. To address the grid dependence, a Coarse Grid Simulation (CGS) framework is proposed (Fu and Hodges, 2005). The CGS will provide a model structure for representing the relationship between empirically-known subgrid features and grid-resolved flow. Therefore, the CGS will lessen the calibration efforts associated with changing model grid scales. In the present work, we demonstrate that grid resolution must affect turbulence calibration for inhomogeneous subgrid-scale physics in standard RANS formulations. Examples are provided to show that through use of the proposed CGS formalism, fine-scale process observed in a fine-grid model can be represented at arbitrary grid scales in a coarse-grid model without ad hoc calibration. Reference Fu, S. and B.R. Hodges (2005), ¡°Grid-scale dependency of subgrid-scale structure effects in hydraulic models of rivers and streams,¡± Mechanics and Materials Conference (McMat 2005), June 1-3, 2005, Louisiana State University, Baton Rouge, Electronic Proceedings (CD-ROM), 5 pgs.

  15. Decision-Support Software for Grid Operators: Transmission Topology Control for Infrastructure Resilience to the Integration of Renewable Generation

    SciTech Connect

    2012-03-16

    GENI Project: The CRA team is developing control technology to help grid operators more actively manage power flows and integrate renewables by optimally turning on and off entire power lines in coordination with traditional control of generation and load resources. The control technology being developed would provide grid operators with tools to help manage transmission congestion by identifying the facilities whose on/off status must change to lower generation costs, increase utilization of renewable resources and improve system reliability. The technology is based on fast optimization algorithms for the near to real-time change in the on/off status of transmission facilities and their software implementation.

  16. Solar cells in series connection by monolithic integration

    NASA Astrophysics Data System (ADS)

    Voss, B.; Knobloch, J.; Goetzberger, A.

    Series-solar-cells by monolithic integration have been developed, using standard semiconductor technology and standard silicon wafer dimensions. The saturation open-circuit-voltage is already obtained at intensities of 0.2 - 0.4 Watt/per sq cm. These cells can be used advantageously as a voltage generator in open circuit- and optocoupler-systems because of the high reliability and longtime stability. The possibility of bifacial illumination makes such cells very suitable in combination with fluorescent collectors.

  17. Integrating structural and functional connectivity to characterize sediment dynamics in a small Alpine catchment

    NASA Astrophysics Data System (ADS)

    Cavalli, Marco; Crema, Stefano; Blok, Michiel; Lucía, Ana; Comiti, Francesco; Marchi, Lorenzo; Keesstra, Saskia

    2016-04-01

    Sediment connectivity can be regarded as a descriptor of the internal linkages between different landscape components within a catchment. The recent focus of the scientific community on connectivity related topics, both concerning hydrological and sediment connectivity, stresses the importance of understanding the main active pathways for a better estimation of energy and matter transfer at catchment scale. This task can be addressed using topography-based indices that analyse the linkages between landscape units. This approach to characterize connectivity is known as structural connectivity. The main limitation of structural connectivity is that it does not account for the processes driving sediment and energy fluxes (i.e., functional connectivity). In this work the integration between structural and functional approaches is proposed for characterizing sediment connectivity in mountain catchments. The structural approach, based on a topography-based sediment connectivity index, was used for assessing hillslope-to-channel connectivity. Since field data on processes driving sediment transport along the channel network are available, a functional approach has been devised to estimate within-channel connectivity. An index of unit stream power computed from the hydraulic properties of the channel (i.e., discharge, slope and channel width) has been compared with the critical unit stream power computed from incipient motion thresholds derived from field data to identify the cells of the Digital Terrain Model (DTM) in which sediment can be mobilized under near-bankfull conditions. The index expressing the within-channel connectivity is given by the length of the reaches consisting of contiguous cells that exceed the critical unit stream power. During high-magnitude floods, when unit stream power values exceed the threshold for incipient motion, channels experience an increase in both hydrological and sediment connectivity. The proposed index characterizes those sections

  18. Software Based Barriers To Integration Of Renewables To The Future Distribution Grid

    SciTech Connect

    Stewart, Emma; Kiliccote, Sila

    2014-06-01

    The future distribution grid has complex analysis needs, which may not be met with the existing processes and tools. In addition there is a growing number of measured and grid model data sources becoming available. For these sources to be useful they must be accurate, and interpreted correctly. Data accuracy is a key barrier to the growth of the future distribution grid. A key goal for California, and the United States, is increasing the renewable penetration on the distribution grid. To increase this penetration measured and modeled representations of generation must be accurate and validated, giving distribution planners and operators confidence in their performance. This study will review the current state of these software and modeling barriers and opportunities for the future distribution grid.

  19. Musical expertise is related to altered functional connectivity during audiovisual integration

    PubMed Central

    Paraskevopoulos, Evangelos; Kraneburg, Anja; Herholz, Sibylle Cornelia; Bamidis, Panagiotis D.; Pantev, Christo

    2015-01-01

    The present study investigated the cortical large-scale functional network underpinning audiovisual integration via magnetoencephalographic recordings. The reorganization of this network related to long-term musical training was investigated by comparing musicians to nonmusicians. Connectivity was calculated on the basis of the estimated mutual information of the sources’ activity, and the corresponding networks were statistically compared. Nonmusicians’ results indicated that the cortical network associated with audiovisual integration supports visuospatial processing and attentional shifting, whereas a sparser network, related to spatial awareness supports the identification of audiovisual incongruences. In contrast, musicians’ results showed enhanced connectivity in regions related to the identification of auditory pattern violations. Hence, nonmusicians rely on the processing of visual clues for the integration of audiovisual information, whereas musicians rely mostly on the corresponding auditory information. The large-scale cortical network underpinning multisensory integration is reorganized due to expertise in a cognitive domain that largely involves audiovisual integration, indicating long-term training-related neuroplasticity. PMID:26371305

  20. Control of modular multilevel converters for grid integration of full-scale wind energy conversion systems

    NASA Astrophysics Data System (ADS)

    Debnath, Suman

    The growing demand for wind power generation has pushed the capacity of wind turbines towards MW power levels. Higher capacity of the wind turbines necessitates operation of the generators and power electronic conversion systems at higher voltage/power levels. The power electronic conversion system of a wind energy conversion system (WECS) needs to meet the stringent requirements in terms of reliability, efficiency, scalability and ease of maintenance, power quality, and dv/dt stress on the generator/transformer. Although the multilevel converters including the neutral point clamped (NPC) converter and the active NPC converter meet most of the requirements, they fall short in reliability and scalability. Motivated by modularity/scalability feature of the modular multilevel converter (MMC), this research is to enable the MMC to meet all of the stringent requirements of the WECS by addressing their unique control challenges. This research presents systematic modeling and control of the MMC to enable it to be a potential converter topology for grid integration of full-scale WECSs. Based on the developed models, appropriate control systems for control of circulating current and capacitor voltages under fixed- and variable-frequency operations are proposed. Using the developed MMC models, a gradient-based cosimulation algorithm to optimize the gains of the developed control systems, is proposed. Performance/effectiveness of the developed models and the proposed control systems for the back-to-back MMC-based WECS are evaluated/verified based on simulations studies in the PSCAD/EMTDC software environment and experimental case studies on a laboratory-scale hardware prototype.

  1. Multi-Lab EV Smart Grid Integration Requirements Study. Providing Guidance on Technology Development and Demonstration

    SciTech Connect

    Markel, T.; Meintz, A.; Hardy, K.; Chen, B.; Bohn, T.; Smart, J.; Scoffield, D.; Hovsapian, R.; Saxena, S.; MacDonald, J.; Kiliccote, S.; Kahl, K.; Pratt, R.

    2015-05-28

    The report begins with a discussion of the current state of the energy and transportation systems, followed by a summary of some VGI scenarios and opportunities. The current efforts to create foundational interface standards are detailed, and the requirements for enabling PEVs as a grid resource are presented. Existing technology demonstrations that include vehicle to grid functions are summarized. The report also includes a data-based discussion on the magnitude and variability of PEVs as a grid resource, followed by an overview of existing simulation tools that vi This report is available at no cost from the National Renewable Energy Laboratory (NREL) at www.nrel.gov/publications. can be used to explore the expansion of VGI to larger grid functions that might offer system and customer value. The document concludes with a summary of the requirements and potential action items that would support greater adoption of VGI.

  2. Development of numerical methods for overset grids with applications for the integrated Space Shuttle vehicle

    NASA Technical Reports Server (NTRS)

    Chan, William M.

    1995-01-01

    Algorithms and computer code developments were performed for the overset grid approach to solving computational fluid dynamics problems. The techniques developed are applicable to compressible Navier-Stokes flow for any general complex configurations. The computer codes developed were tested on different complex configurations with the Space Shuttle launch vehicle configuration as the primary test bed. General, efficient and user-friendly codes were produced for grid generation, flow solution and force and moment computation.

  3. Using Conventional Hydropower to Help Alleviate Variable Resource Grid Integration Challenges in the Western U.S

    NASA Astrophysics Data System (ADS)

    Veselka, T. D.; Poch, L.

    2011-12-01

    Integrating high penetration levels of wind and solar energy resources into the power grid is a formidable challenge in virtually all interconnected systems due to the fact that supply and demand must remain in balance at all times. Since large scale electricity storage is currently not economically viable, generation must exactly match electricity demand plus energy losses in the system as time unfolds. Therefore, as generation from variable resources such as wind and solar fluctuate, production from generating resources that are easier to control and dispatch need to compensate for these fluctuations while at the same time respond to both instantaneous change in load and follow daily load profiles. The grid in the Western U.S. is not exempt to grid integration challenges associated with variable resources. However, one advantage that the power system in the Western U.S. has over many other regional power systems is that its footprint contains an abundance of hydropower resources. Hydropower plants, especially those that have reservoir water storage, can physically change electricity production levels very quickly both via a dispatcher and through automatic generation control. Since hydropower response time is typically much faster than other dispatchable resources such as steam or gas turbines, it is well suited to alleviate variable resource grid integration issues. However, despite an abundance of hydropower resources and the current low penetration of variable resources in the Western U.S., problems have already surfaced. This spring in the Pacific Northwest, wetter than normal hydropower conditions in combination with transmission constraints resulted in controversial wind resource shedding. This action was taken since water spilling would have increased dissolved oxygen levels downstream of dams thereby significantly degrading fish habitats. The extent to which hydropower resources will be able to contribute toward a stable and reliable Western grid is

  4. Renewable Electricity Grid Integration Roadmap for Mexico. Supplement to the IEA Expert Group Report on Recommended Practices for Wind Integration Studies

    SciTech Connect

    Parsons, Brian; Cochran, Jaquelin; Watson, Andrea; Katz, Jessica; Bracho, Ricardo

    2015-08-19

    As a recognized leader in efforts to mitigate global climate change, the Government of Mexico (GOM) works proactively to reduce emissions, demonstrating strong political will and capacity to comprehensively address climate change. Since 2010, the U.S. government (USG) has supported these efforts by partnering with Mexico under the Enhancing Capacity for Low Emission Development Strategies (EC-LEDS) program. Through the program, the USG has partnered with Mexico’s Ministry of Energy (SENER), as well as other government agencies, to support GOM in reaching its clean energy and climate change goals. Specifically, the EC-LEDS program is supporting GOM’s clean energy goal of generating 35% of its electricity from renewable energy (RE) by 2024. EC-LEDS, through the U.S. Agency for International Development (USAID) and the U.S Department of Energy’s (DOE’s) National Renewable Energy Laboratory (NREL), has been collaborating with SENER and GOM interagency working group—the Consejo Consultivo para las Energías Renovables (Consultative Council on Renewable Energy)—to create a grid integration roadmap for variable RE. 1 A key objective in creating a grid integration roadmap is assessing likely impacts of wind and solar energy on the power system and modifying planning and operations accordingly. This paper applies best practices in conducting a grid integration study to the Mexican context.

  5. Selection of battery technology to support grid-integrated renewable electricity

    NASA Astrophysics Data System (ADS)

    Leadbetter, Jason; Swan, Lukas G.

    2012-10-01

    Operation of the electricity grid has traditionally been done using slow responding base and intermediate load generators with fast responding peak load generators to capture the chaotic behavior of end-use demands. Many modern electricity grids are implementing intermittent non-dispatchable renewable energy resources. As a result, the existing support services are becoming inadequate and technological innovation in grid support services are necessary. Support services fall into short (seconds to minutes), medium (minutes to hours), and long duration (several hours) categories. Energy storage offers a method of providing these services and can enable increased penetration rates of renewable energy generators. Many energy storage technologies exist. Of these, batteries span a significant range of required storage capacity and power output. By assessing the energy to power ratio of electricity grid services, suitable battery technologies were selected. These include lead-acid, lithium-ion, sodium-sulfur, and vanadium-redox. Findings show the variety of grid services require different battery technologies and batteries are capable of meeting the short, medium, and long duration categories. A brief review of each battery technology and its present state of development, commercial implementation, and research frontiers is presented to support these classifications.

  6. GridMan: A grid manipulation system

    NASA Technical Reports Server (NTRS)

    Eiseman, Peter R.; Wang, Zhu

    1992-01-01

    GridMan is an interactive grid manipulation system. It operates on grids to produce new grids which conform to user demands. The input grids are not constrained to come from any particular source. They may be generated by algebraic methods, elliptic methods, hyperbolic methods, parabolic methods, or some combination of methods. The methods are included in the various available structured grid generation codes. These codes perform the basic assembly function for the various elements of the initial grid. For block structured grids, the assembly can be quite complex due to a large number of clock corners, edges, and faces for which various connections and orientations must be properly identified. The grid generation codes are distinguished among themselves by their balance between interactive and automatic actions and by their modest variations in control. The basic form of GridMan provides a much more substantial level of grid control and will take its input from any of the structured grid generation codes. The communication link to the outside codes is a data file which contains the grid or section of grid.

  7. PhotoVoltaic distributed generation for Lanai power grid real-time simulation and control integration scenario.

    SciTech Connect

    Robinett, Rush D., III; Kukolich, Keith; Wilson, David Gerald; Schenkman, Benjamin L.

    2010-06-01

    This paper discusses the modeling, analysis, and testing in a real-time simulation environment of the Lanai power grid system for the integration and control of PhotoVoltaic (PV) distributed generation. The Lanai Island in Hawaii is part of the Hawaii Clean Energy Initiative (HCEI) to transition to 30% renewable green energy penetration by 2030. In Lanai the primary loads come from two Castle and Cook Resorts, in addition to residential needs. The total peak load profile is 12470 V, 5.5 MW. Currently there are several diesel generators that meet these loading requirements. As part of the HCEI, Lanai has initially installed 1.2 MW of PV generation. The goal of this study has been to evaluate the impact of the PV with respect to the conventional carbon-based diesel generation in real time simulation. For intermittent PV distributed generation, the overall stability and transient responses are investigated. A simple Lanai 'like' model has been developed in the Matlab/Simulink environment (see Fig. 1) and to accommodate real-time simulation of the hybrid power grid system the Opal-RT Technologies RT-Lab environment is used. The diesel generators have been modelled using the SimPowerSystems toolbox swing equations and a custom Simulink module has been developed for the High level PV generation. All of the loads have been characterized primarily as distribution lines with series resistive load banks with one VAR load bank. Three-phase faults are implemented for each bus. Both conventional and advanced control architectures will be used to evaluate the integration of the PV onto the current power grid system. The baseline numerical results include the stable performance of the power grid during varying cloud cover (PV generation ramping up/down) scenarios. The importance of assessing the real-time scenario is included.

  8. Performance of monolithic integrated series-connected GaAs solar cells under concentrated light

    NASA Astrophysics Data System (ADS)

    Seno, Minato; Watanabe, Kentaroh; Sugiyama, Masakazu; Nakano, Yoshiaki

    2013-09-01

    The concentrator photovoltaic (CPV) system provides excellent cost performance and conversion efficiency by increasing the concentration ratio. The problem is that concentration ratio is limited by short-circuit current density (Jsc) due to cell resistance loss. In order to achieve much larger concentration ratio, the monolithically integrated series-connected GaAs photovoltaic (PV) cells were fabricated. By dividing a cell into sub-cells on a chip and connecting them in series, the cell provides smaller short-circuit current (Isc) and larger open-circuit voltage (Voc). This approach can reduce joule energy loss inside a cell without decreasing electrical power output and allow much larger concentration ratio. In our design, 10 series-connected sub-cells, with bypass diodes in parallel with each sub-cell, were integrated monolithically on semi-insulating GaAs. When some sub-cells in the array were shaded, the bypass diodes prevented the shaded sub-cells from breakdown and reduced fluctuation of power output. The detection area of a unit cell was 1.73 mm2 and an entire detection area occupied over 68% of the whole chip area. The arrayed 10 cells exhibited Voc of 9.0 V under illumination (AM 1.5G). The series-connected cell achieved maximum efficiency at higher concentration ratio than non-series-connected cell.

  9. NREL Energy Models Examine the Potential for Wind and Solar Grid Integration (Fact Sheet)

    SciTech Connect

    Not Available

    2013-11-01

    As renewable energy generating sources, such as wind turbines and solar power systems, reach high levels of penetration in parts of the United States, the National Renewable Energy Laboratory (NREL) is helping the utility industry to peer into the future. Using software modeling tools that the lab developed, NREL is examining the future operation of the electrical grid as renewable energy continues to grow.

  10. Grid oscillators

    NASA Technical Reports Server (NTRS)

    Popovic, Zorana B.; Kim, Moonil; Rutledge, David B.

    1988-01-01

    Loading a two-dimensional grid with active devices offers a means of combining the power of solid-state oscillators in the microwave and millimeter-wave range. The grid structure allows a large number of negative resistance devices to be combined. This approach is attractive because the active devices do not require an external locking signal, and the combining is done in free space. In addition, the loaded grid is a planar structure amenable to monolithic integration. Measurements on a 25-MESFET grid at 9.7 GHz show power-combining and frequency-locking without an external locking signal, with an ERP of 37 W. Experimental far-field patterns agree with theoretical results obtained using reciprocity.

  11. Prioritizing Urban Habitats for Connectivity Conservation: Integrating Centrality and Ecological Metrics.

    PubMed

    Poodat, Fatemeh; Arrowsmith, Colin; Fraser, David; Gordon, Ascelin

    2015-09-01

    Connectivity among fragmented areas of habitat has long been acknowledged as important for the viability of biological conservation, especially within highly modified landscapes. Identifying important habitat patches in ecological connectivity is a priority for many conservation strategies, and the application of 'graph theory' has been shown to provide useful information on connectivity. Despite the large number of metrics for connectivity derived from graph theory, only a small number have been compared in terms of the importance they assign to nodes in a network. This paper presents a study that aims to define a new set of metrics and compares these with traditional graph-based metrics, used in the prioritization of habitat patches for ecological connectivity. The metrics measured consist of "topological" metrics, "ecological metrics," and "integrated metrics," Integrated metrics are a combination of topological and ecological metrics. Eight metrics were applied to the habitat network for the fat-tailed dunnart within Greater Melbourne, Australia. A non-directional network was developed in which nodes were linked to adjacent nodes. These links were then weighted by the effective distance between patches. By applying each of the eight metrics for the study network, nodes were ranked according to their contribution to the overall network connectivity. The structured comparison revealed the similarity and differences in the way the habitat for the fat-tailed dunnart was ranked based on different classes of metrics. Due to the differences in the way the metrics operate, a suitable metric should be chosen that best meets the objectives established by the decision maker. PMID:25924790

  12. A Feasibility Study on HTS Cable for the Grid Integration of Renewable Energy

    NASA Astrophysics Data System (ADS)

    Yoon, D.-H.

    Nowadays there are a lot of demands for the renewable energy generation because fossil fuel is being exhausted. The size of renewable plant has a tendency to be increased for economic reasons. So the high voltage level facilities are necessary for interconnection between power grid and renewable plant. The interconnection facilities should have a transmission capacity enough to transfer the peak power generated by renewable plant. However, the output of renewable has an intermittent characteristic and its variation range is not small. Therefore an average utilization ratio of interconnection line between is low because of the power fluctuation from renewable plant. The High Temperature Superconducting (HTS) cable is able to transmit a large amount of electricity without additional power facility. In this paper, an advantage of using HTS cable as an interconnection line between power grid and renewable plant are analyzed.

  13. Grid Interaction Technical Team Roadmap

    SciTech Connect

    2013-06-01

    The mission of the Grid Interaction Technical Team (GITT) is to support a transition scenario to large scale grid-connected vehicle charging with transformational technology, proof of concept and information dissemination. The GITT facilitates technical coordination and collaboration between vehicle-grid connectivity and communication activities among U.S. DRIVE government and industry partners.

  14. Thalamotemporal impairment in temporal lobe epilepsy: A combined MRI analysis of structure, integrity, and connectivity

    PubMed Central

    Keller, Simon S; O'Muircheartaigh, Jonathan; Traynor, Catherine; Towgood, Karren; Barker, Gareth J; Richardson, Mark P

    2014-01-01

    Objective Thalamic abnormality in temporal lobe epilepsy (TLE) is well known from imaging studies, but evidence is lacking regarding connectivity profiles of the thalamus and their involvement in the disease process. We used a novel multisequence magnetic resonance imaging (MRI) protocol to elucidate the relationship between mesial temporal and thalamic pathology in TLE. Methods For 23 patients with TLE and 23 healthy controls, we performed T1-weighted (for analysis of tissue structure), diffusion tensor imaging (tissue connectivity), and T1 and T2 relaxation (tissue integrity) MRI across the whole brain. We used connectivity-based segmentation to determine connectivity patterns of thalamus to ipsilateral cortical regions (occipital, parietal, prefrontal, postcentral, precentral, and temporal). We subsequently determined volumes, mean tractography streamlines, and mean T1 and T2 relaxometry values for each thalamic segment preferentially connecting to a given cortical region, and of the hippocampus and entorhinal cortex. Results As expected, patients had significant volume reduction and increased T2 relaxation time in ipsilateral hippocampus and entorhinal cortex. There was bilateral volume loss, mean streamline reduction, and T2 increase of the thalamic segment preferentially connected to temporal lobe, corresponding to anterior, dorsomedial, and pulvinar thalamic regions, with no evidence of significant change in any other thalamic segments. Left and right thalamotemporal segment volume and T2 were significantly correlated with volume and T2 of ipsilateral (epileptogenic), but not contralateral (nonepileptogenic), mesial temporal structures. Significance These convergent and robust data indicate that thalamic abnormality in TLE is restricted to the area of the thalamus that is preferentially connected to the epileptogenic temporal lobe. The degree of thalamic pathology is related to the extent of mesial temporal lobe damage in TLE. PMID:24447099

  15. The Benefits of Grid Networks

    ERIC Educational Resources Information Center

    Tennant, Roy

    2005-01-01

    In the article, the author talks about the benefits of grid networks. In speaking of grid networks the author is referring to both networks of computers and networks of humans connected together in a grid topology. Examples are provided of how grid networks are beneficial today and the ways in which they have been used.

  16. VOLTTRON™: An Agent Platform for Integrating Electric Vehicles and Smart Grid

    SciTech Connect

    Haack, Jereme N.; Akyol, Bora A.; Tenney, Nathan D.; Carpenter, Brandon J.; Pratt, Richard M.; Carroll, Thomas E.

    2013-12-06

    The VOLTTRON™ platform provides a secure environment for the deployment of intelligent applications in the smart grid. VOLTTRON design is based on the needs of control applications running on small form factor devices, namely security and resource guarantees. Services such as resource discovery, secure agent mobility, and interacting with smart and legacy devices are provided by the platform to ease the development of control applications and accelerate their deployment. VOLTTRON platform has been demonstrated in several different domains that influenced and enhanced its capabilities. This paper will discuss the features of VOLTTRON and highlight its usage to coordinate electric vehicle charging with home energy usage

  17. Very Large-Scale Deployment of Grid-Connected Solar Photovoltaics in the United States: Challenges and Opportunities; Preprint

    SciTech Connect

    Denholm, P.; Margolis, R.

    2006-04-01

    This paper analyzes the potential for solar photovoltaics (PV) to be deployed on a very large scale and provide a large fraction of a system's electricity. It explicitly examines how the hourly availability of PV interacts with the limited flexibility of traditional electricity generation plants. The authors found that, under high penetration levels and existing grid-operation procedures and rules, the system will have excess PV generation during certain periods of the year. This excess PV generation results in increased costs, which can increase dramatically when PV provides on the order of 10%-15% of total electricity demand in systems that are heavily dependent on inflexible baseload steam plants. Measures to increase penetration of PV are also discussed, including increased system flexibility, increased dispatchable load, and energy storage.

  18. Implementation of the Kirchhoff integral for elastic waves in staggered-grid modeling schemes

    SciTech Connect

    Mittet, R. )

    1994-12-01

    Implementation of boundary conditions in finite-difference schemes is not straightforward for the elastic wave equation if a staggered grid formulation is used. Reverse time migration of VSP data requires a proper description of the recording surface so as not to excite false P- and S-waves. Such contributions may cause artifacts in the imaging procedure. The boundary conditions for the elastic stress tensor can be implemented numerically in a staggered coarse grid modeling scheme by using band-limited spatial delta-functions and band-limited first-order derivatives of these spatial delta-functions. A representation theorem for elastic waves is derived to test the implementation of the spatial part of the boundary condition. The implementation is tested in a 2-D numerical experiment for a closed, but curved, boundary S enclosing a volume V. The test condition is that within the volume V, the difference between the forward modeled field and the retropropagated field should be equal to zero. Both P- and S-waves are properly recovered in a 2-D reverse time modeling example. The numerical artifacts related to the proposed spatial approximation of the boundary condition are found to be negligible.

  19. Comparative Evaluation for Brain Structural Connectivity Approaches: Towards Integrative Neuroinformatics Tool for Epilepsy Clinical Research.

    PubMed

    Yang, Sheng; Tatsuoka, Curtis; Ghosh, Kaushik; Lacuey-Lecumberri, Nuria; Lhatoo, Samden D; Sahoo, Satya S

    2016-01-01

    Recent advances in brain fiber tractography algorithms and diffusion Magnetic Resonance Imaging (MRI) data collection techniques are providing new approaches to study brain white matter connectivity, which play an important role in complex neurological disorders such as epilepsy. Epilepsy affects approximately 50 million persons worldwide and it is often described as a disorder of the cortical network organization. There is growing recognition of the need to better understand the role of brain structural networks in the onset and propagation of seizures in epilepsy using high resolution non-invasive imaging technologies. In this paper, we perform a comparative evaluation of two techniques to compute structural connectivity, namely probabilistic fiber tractography and statistics derived from fractional anisotropy (FA), using diffusion MRI data from a patient with rare case of medically intractable insular epilepsy. The results of our evaluation demonstrate that probabilistic fiber tractography provides a more accurate map of structural connectivity and may help address inherent complexities of neural fiber layout in the brain, such as fiber crossings. This work provides an initial result towards building an integrative informatics tool for neuroscience that can be used to accurately characterize the role of fiber tract connectivity in neurological disorders such as epilepsy. PMID:27570685

  20. Comparative Evaluation for Brain Structural Connectivity Approaches: Towards Integrative Neuroinformatics Tool for Epilepsy Clinical Research

    PubMed Central

    Yang, Sheng; Tatsuoka, Curtis; Ghosh, Kaushik; Lacuey-Lecumberri, Nuria; Lhatoo, Samden D.; Sahoo, Satya S.

    2016-01-01

    Recent advances in brain fiber tractography algorithms and diffusion Magnetic Resonance Imaging (MRI) data collection techniques are providing new approaches to study brain white matter connectivity, which play an important role in complex neurological disorders such as epilepsy. Epilepsy affects approximately 50 million persons worldwide and it is often described as a disorder of the cortical network organization. There is growing recognition of the need to better understand the role of brain structural networks in the onset and propagation of seizures in epilepsy using high resolution non-invasive imaging technologies. In this paper, we perform a comparative evaluation of two techniques to compute structural connectivity, namely probabilistic fiber tractography and statistics derived from fractional anisotropy (FA), using diffusion MRI data from a patient with rare case of medically intractable insular epilepsy. The results of our evaluation demonstrate that probabilistic fiber tractography provides a more accurate map of structural connectivity and may help address inherent complexities of neural fiber layout in the brain, such as fiber crossings. This work provides an initial result towards building an integrative informatics tool for neuroscience that can be used to accurately characterize the role of fiber tract connectivity in neurological disorders such as epilepsy. PMID:27570685

  1. Connective tissue integrity is lost in vitamin B-6-deficient chicks

    NASA Technical Reports Server (NTRS)

    Masse, P. G.; Yamauchi, M.; Mahuren, J. D.; Coburn, S. P.; Muniz, O. E.; Howell, D. S.

    1995-01-01

    The objective of the present investigation was to characterize further the connective tissue disorder produced by pyridoxine (vitamin B-6) deficiency, as previously evidenced by electron microscopy. Following the second post-natal week, fast growing male chicks were deprived of pyridoxine for a 1-mo period. Six weeks post-natally, blood concentrations in the experimental deficiency group had declined to deficiency levels as registered by low concentrations of pyridoxal phosphate (coenzyme form) in erythrocytes, but did not reach levels associated with neurological symptoms. Light microscopic study showed abnormalities in the extracellular matrix of the connective tissues. Collagen cross-links and the aldehyde contents were not significantly lower in cartilage and tendon collagens of vitamin B-6-deficient animals than in age-matched controls; also, their proteoglycan degrading protease and collagenase activities measured in articular cartilages were not greater. Thus, proteolysis was an unlikely alternative mechanism to account for the loss of connective tissue integrity. These results point to the need for further investigation into adhesive properties of collagen associated proteoglycans or other proteins in vitamin B-6-deficient connective tissue.

  2. ESIF Plugs Utility-Scale Hardware into Simulated Grids to Assess Integration Effects (Fact Sheet)

    SciTech Connect

    Not Available

    2014-04-01

    At NREL's Energy Systems Integration Facility (ESIF), integrated, megawatt-scale power hardware-in-the-loop (PHIL) capability allows researchers and manufacturers to test new energy technologies at full power in real-time simulations - safely evaluating component and system performance and reliability before going to market.

  3. Photovoltaic solar system connected to the electric power grid operating as active power generator and reactive power compensator

    SciTech Connect

    Albuquerque, Fabio L.; Moraes, Adelio J.; Guimaraes, Geraldo C.; Sanhueza, Sergio M.R.; Vaz, Alexandre R.

    2010-07-15

    In the case of photovoltaic (PV) systems acting as distributed generation (DG) systems, the DC energy that is produced is fed to the grid through the power-conditioning unit (inverter). The majority of contemporary inverters used in DG systems are current source inverters (CSI) operating at unity power factor. If, however, we assume that voltage source inverters (VSI) can replace CSIs, we can generate reactive power proportionally to the remaining unused capacity at any given time. According to the theory of instantaneous power, the inverter reactive power can be regulated by changing the amplitude of its output voltage. In addition, the inverter active power can be adjusted by modifying the phase angle of its output voltage. Based on such theory, both the active power supply and the reactive power compensation (RPC) can be carried out simultaneously. When the insolation is weak or the PV modules are inoperative at night, the RPC feature of a PV system can still be used to improve the inverter utilisation factor. Some MATLAB simulation results are included here to show the feasibility of the method. (author)

  4. Results from an investigation of the integration of wind energy into the El Paso Electric grid system

    SciTech Connect

    Moroz, E.M.; Parks, N.J.; Swift, A.H.; Traichal, P.A.

    1997-12-31

    This paper documents some preliminary results from an evaluation of the costs and benefits to be gained from the integration of wind generated electricity into the El Paso Electric grid system. The study focused on the utilization of the considerable known wind potential of the Guadalupe/Delaware Mountains region, but also looked at other energetic wind resources within 15 miles of El Paso Electric`s Grid. The original project`s goal was to identify the added value of wind in terms of jobs, line support, risk reduction etc., that wind energy could bring to El Paso Electric. Although these goals have not yet been achieved the potential for water savings and reductions in gaseous emissions have been documented. Thus this paper focuses mainly on the water consumption and criteria pollutant emissions that could be avoided by adding wind energy to El Paso Electric`s generation mix. Preliminary data from a renewables attitude survey indicates that, from the 338 respondents, there is overwhelming public support for utilizing such renewable sources of electricity. This case study, which should be of direct relevance to the arid southwestern states and beyond, was sponsored by the Environmental Protection Agency (EPA) and conducted in cooperation with El Paso Electric.

  5. mantisGRID: a grid platform for DICOM medical images management in Colombia and Latin America.

    PubMed

    Garcia Ruiz, Manuel; Garcia Chaves, Alvin; Ruiz Ibañez, Carlos; Gutierrez Mazo, Jorge Mario; Ramirez Giraldo, Juan Carlos; Pelaez Echavarria, Alejandro; Valencia Diaz, Edison; Pelaez Restrepo, Gustavo; Montoya Munera, Edwin Nelson; Garcia Loaiza, Bernardo; Gomez Gonzalez, Sebastian

    2011-04-01

    This paper presents the mantisGRID project, an interinstitutional initiative from Colombian medical and academic centers aiming to provide medical grid services for Colombia and Latin America. The mantisGRID is a GRID platform, based on open source grid infrastructure that provides the necessary services to access and exchange medical images and associated information following digital imaging and communications in medicine (DICOM) and health level 7 standards. The paper focuses first on the data abstraction architecture, which is achieved via Open Grid Services Architecture Data Access and Integration (OGSA-DAI) services and supported by the Globus Toolkit. The grid currently uses a 30-Mb bandwidth of the Colombian High Technology Academic Network, RENATA, connected to Internet 2. It also includes a discussion on the relational database created to handle the DICOM objects that were represented using Extensible Markup Language Schema documents, as well as other features implemented such as data security, user authentication, and patient confidentiality. Grid performance was tested using the three current operative nodes and the results demonstrated comparable query times between the mantisGRID (OGSA-DAI) and Distributed mySQL databases, especially for a large number of records. PMID:20127269

  6. Integrated Care and Connected Health Approaches Leveraging Personalised Health through Big Data Analytics.

    PubMed

    Maglaveras, Nicos; Kilintzis, Vassilis; Koutkias, Vassilis; Chouvarda, Ioanna

    2016-01-01

    Integrated care and connected health are two fast evolving concepts that have the potential to leverage personalised health. From the one side, the restructuring of care models and implementation of new systems and integrated care programs providing coaching and advanced intervention possibilities, enable medical decision support and personalized healthcare services. From the other side, the connected health ecosystem builds the means to follow and support citizens via personal health systems in their everyday activities and, thus, give rise to an unprecedented wealth of data. These approaches are leading to the deluge of complex data, as well as in new types of interactions with and among users of the healthcare ecosystem. The main challenges refer to the data layer, the information layer, and the output of information processing and analytics. In all the above mentioned layers, the primary concern is the quality both in data and information, thus, increasing the need for filtering mechanisms. Especially in the data layer, the big biodata management and analytics ecosystem is evolving, telemonitoring is a step forward for data quality leverage, with numerous challenges still left to address, partly due to the large number of micro-nano sensors and technologies available today, as well as the heterogeneity in the users' background and data sources. This leads to new R&D pathways as it concerns biomedical information processing and management, as well as to the design of new intelligent decision support systems (DSS) and interventions for patients. In this paper, we illustrate these issues through exemplar research targeting chronic patients, illustrating the current status and trends in PHS within the integrated care and connected care world. PMID:27225565

  7. Development and Operation of the D-Grid Infrastructure

    NASA Astrophysics Data System (ADS)

    Fieseler, Thomas; Gűrich, Wolfgang

    D-Grid is the German national grid initiative, granted by the German Federal Ministry of Education and Research. In this paper we present the Core D-Grid which acts as a condensation nucleus to build a production grid and the latest developments of the infrastructure. The main difference compared to other international grid initiatives is the support of three middleware systems, namely LCG/gLite, Globus, and UNICORE for compute resources. Storage resources are connected via SRM/dCache and OGSA-DAI. In contrast to homogeneous communities, the partners in Core D-Grid have different missions and backgrounds (computing centres, universities, research centres), providing heterogeneous hardware from single processors to high performance supercomputing systems with different operating systems. We present methods to integrate these resources and services for the DGrid infrastructure like a point of information, centralized user and virtual organization management, resource registration, software provision, and policies for the implementation (firewalls, certificates, user mapping).

  8. Building resilient power grids from integrated risk governance perspective: A lesson learned from china's 2008 Ice-Snow Storm disaster

    NASA Astrophysics Data System (ADS)

    Ye, Qian

    2014-10-01

    In the past three decades, the electric energy industry made great contribution to support rapid social and economic development in China, and meanwhile has been grown at the highest rate in the human history owing to the economic reform. In its new national development plan, more investment has been put into installation of both electricity generating capacity and transmitting capacity in order to meet fast growing demand of electric energy. However, energy resources, both fossil fuel and renewable types, and energy consumption and load centers in China are not evenly distributed in both spatial and temporal dimensions. Moreover, dominated by coal as its primary energy source, the whole eastern China is now entering an environmental crisis in which pollutants emitted by coal power plants contribute a large part. To balance the regional differences in energy sources and energy consumption while meeting the steadily increasing demands for electric energy for the whole country, in addition to increase electric generating capacity, building large-scale, long-distance ultra high voltage power grids is the top priority for next five years. China is a country prone to almost all kinds of natural disasters due to its vast, complex geographical and climatic conditions. In recent years, frequent natural disasters, especially extreme weather and climate events, have threatened the safety, reliability and stability of electric energy system in China. Unfortunately, with fast growth rate but lacking of risk assessing and prevention mechanism, many infrastructure constructions, including national power grids, are facing integrated and complex economic, social, institutional and ecological risks. In this paper, based on a case analysis of the Great Ice Storm in southern China in January 2008, risks of building a resilient power grid to deal with increasing threats from extreme weathers are discussed. The paper recommends that a systematic approach based on the social

  9. A semantic Grid Infrastructure Enabling Integrated Access and Knowledge Discovery from Multilevel Data in Ppost-Genomic Clinical Trials

    NASA Astrophysics Data System (ADS)

    Tsiknakis, Manolis; Sfakianakis, Stelios; Potamias, George; Zacharioudakis, Giorgos; Kafetzopoulos, Dimitris

    This paper reports on original results of the ACGT integrated project focusing on the design and development of a European Biomedical Grid infrastructure in support of multicentric, post genomic clinical trials on Cancer. The paper provides a presentation of the needs of users involved in post-genomic CTs, and presents such needs in the form of scenarios which drive the requirements engineering phase of the project. Subsequently, the initial architecture specified by the project is presented and its services are classified and discussed. The Master Ontology on Cancer, been developed by the project, is presented and our approach to develop the required metadata registries, which provide semantically rich information about available data and computational services, is provided. Finally, a short discussion of the work lying ahead is included.

  10. The Association of Aging with White Matter Integrity and Functional Connectivity Hubs

    PubMed Central

    Yang, Albert C.; Tsai, Shih-Jen; Liu, Mu-En; Huang, Chu-Chung; Lin, Ching-Po

    2016-01-01

    Normal aging is associated with reduced cerebral structural integrity and altered functional brain activity, yet the association of aging with the relationship between structural and functional brain changes remains unclear. Using combined diffusion tensor imaging (DTI) and functional magnetic resonance imaging (fMRI) modalities, we hypothesized that aging-related changes in white matter integrity (i.e., fractional anisotropy) was associated with the short- or long-range functional connectivity density (FCD) in hub regions. We tested this hypothesis by using a healthy aging cohort comprised of 140 younger adults aged 20–39 years and 109 older adults aged 60–79 years. Compared with the younger group, older adults exhibited widespread reductions in white matter integrity with selective preservation in brain stem tracts and the cingulum connected to the hippocampus and cingulate cortex, whereas FCD mapping in older adults showed a reduced FCD in the visual, somatosensory, and motor functional networks and an increased FCD in the default mode network. The older adults exhibited significantly increased short- or long-range FCD in functional hubs of the precuneus, posterior, and middle cingulate, and thalamus, hippocampus, fusiform, and inferior temporal cortex. Furthermore, DTI-fMRI relationship were predominantly identified in older adults in whom short- and long-range FCD in the left precuneus was negatively correlated to structural integrity of adjacent and nonadjacent white matter tracts, respectively. We also found that long-range FCD in the left precuneus was positively correlated to cognitive function. These results support the compensatory hypothesis of neurocognitive aging theory and reveal the DTI-fMRI relationship associated with normal aging. PMID:27378915