WorldWideScience

Sample records for wind driven electrical

  1. Wind power demonstration and siting problems. [for recharging electrically driven automobiles

    Science.gov (United States)

    Bergey, K. H.

    1973-01-01

    Technical and economic feasibility studies on a small windmill to provide overnight charging for an electrically driven car are reported. The auxiliary generator provides power for heating and cooling the vehicle which runs for 25 miles on battery power alone, and for 50 miles with the onboard charger operating. The blades for this windmill have a diameter of 12 feet and are coupled through to a conventional automobile alternator so that they are able to completely recharge car batteries in 8 hours. Optimization of a windmill/storage system requires detailed wind velocity information which permits rational sitting of wind power system stations.

  2. Treatment Wetland Aeration without Electricity? Lessons Learned from the First Experiment Using a Wind-Driven Air Pump

    Directory of Open Access Journals (Sweden)

    Johannes Boog

    2016-11-01

    Full Text Available Aerated treatment wetlands have become an increasingly recognized technology for treating wastewaters from domestic and various industrial origins. To date, treatment wetland aeration is provided by air pumps which require access to the energy grid. The requirement for electricity increases the ecological footprint of an aerated wetland and limits the application of this technology to areas with centralized electrical infrastructure. Wind power offers another possibility as a driver for wetland aeration, but its use for this purpose has not yet been investigated. This paper reports the first experimental trial using a simple wind-driven air pump to replace the conventional electric air blowers of an aerated horizontal subsurface flow wetland. The wind-driven air pump was connected to a two-year old horizontal flow aerated wetland which had been in continuous (24 h aeration since startup. The wind-driven aeration system functioned, however it was not specifically adapted to wetland aeration. As a result, treatment performance decreased compared to prior continuous aeration. Inconsistent wind speed at the site may have resulted in insufficient pressure within the aeration manifold, resulting in insufficient air supply to the wetland. This paper discusses the lessons learned during the experiment.

  3. Wind power. [electricity generation

    Science.gov (United States)

    Savino, J. M.

    1975-01-01

    A historical background on windmill use, the nature of wind, wind conversion system technology and requirements, the economics of wind power and comparisons with alternative systems, data needs, technology development needs, and an implementation plan for wind energy are presented. Considerable progress took place during the 1950's. Most of the modern windmills feature a wind turbine electricity generator located directly at the top of their rotor towers.

  4. Wind farm electrical system

    Science.gov (United States)

    Erdman, William L.; Lettenmaier, Terry M.

    2006-07-04

    An approach to wind farm design using variable speed wind turbines with low pulse number electrical output. The output of multiple wind turbines are aggregated to create a high pulse number electrical output at a point of common coupling with a utility grid network. Power quality at each individual wind turbine falls short of utility standards, but the aggregated output at the point of common coupling is within acceptable tolerances for utility power quality. The approach for aggregating low pulse number electrical output from multiple wind turbines relies upon a pad mounted transformer at each wind turbine that performs phase multiplication on the output of each wind turbine. Phase multiplication converts a modified square wave from the wind turbine into a 6 pulse output. Phase shifting of the 6 pulse output from each wind turbine allows the aggregated output of multiple wind turbines to be a 24 pulse approximation of a sine wave. Additional filtering and VAR control is embedded within the wind farm to take advantage of the wind farm's electrical impedence characteristics to further enhance power quality at the point of common coupling.

  5. Offshore Floating Wind Turbine-driven Deep Sea Water Pumping for Combined Electrical Power and District Cooling

    Science.gov (United States)

    Sant, T.; Buhagiar, D.; Farrugia, R. N.

    2014-06-01

    A new concept utilising floating wind turbines to exploit the low temperatures of deep sea water for space cooling in buildings is presented. The approach is based on offshore hydraulic wind turbines pumping pressurised deep sea water to a centralised plant consisting of a hydro-electric power system coupled to a large-scale sea water-cooled air conditioning (AC) unit of an urban district cooling network. In order to investigate the potential advantages of this new concept over conventional technologies, a simplified model for performance simulation of a vapour compression AC unit was applied independently to three different systems, with the AC unit operating with (1) a constant flow of sea surface water, (2) a constant flow of sea water consisting of a mixture of surface sea water and deep sea water delivered by a single offshore hydraulic wind turbine and (3) an intermittent flow of deep sea water pumped by a single offshore hydraulic wind turbine. The analysis was based on one year of wind and ambient temperature data for the Central Mediterranean that is known for its deep waters, warm climate and relatively low wind speeds. The study confirmed that while the present concept is less efficient than conventional turbines utilising grid-connected electrical generators, a significant portion of the losses associated with the hydraulic transmission through the pipeline are offset by the extraction of cool deep sea water which reduces the electricity consumption of urban air-conditioning units.

  6. E-region wind-driven electrical coupling of patchy sporadic-E and spread-F at midlatitude

    Directory of Open Access Journals (Sweden)

    C. Haldoupis

    2005-09-01

    Full Text Available This paper investigates the role of neutral winds in the generation of relatively large polarization electric fields across patchy sporadic-E layers, which then map upward to the F region, to create conditions for medium-scale spread-F. The calculations are based on an analytical model that uses the current continuity equation and field-aligned current closures to the F region in order to describe quantitatively a Hall polarization process inside sporadic-E plasma patches during nighttime. In applying this model we use experimentally known values for E and F region, conductances, the ambient electric fields and prevailing neutral winds, in order to estimate the polarization fields that build up inside sporadic-E. It is found that the relatively strong west-southwest neutral winds during summer nighttime can provide the free energy for the generation of sizable polarization electric fields, which have comparable eastward and north-upward components and reach values of several mV/m. Given that the sporadic-E patches have sizes from a few to several tens of kilometers, the polarization fields can map easily to the F region bottomside where they impact ExB plasma uplifts and westward bulk motions, in line with key observational properties of medium-scale spread-F. However, the present simple model needs further development to also include wind forcing of the F region plasma and possible polarization processes inside spread-F. Keywords. Ionosphere (Electric fields and currents; Ionospheric irregularities; Mid-latitude ionosphere

  7. Wind driven mobile charging of automobile battery- A case study ...

    African Journals Online (AJOL)

    This paper deals with implementation of mobile wind driven generator technology to produce electricity in charging of two wheeler (12V) automobile battery. The use of PWM methodology with pulse charging method at a constant rate has been adopted for this purpose. The low speed PMSG driven by wind at speed of ...

  8. Wind-driven pyroelectric energy harvesting device

    Science.gov (United States)

    Xie, Mengying; Zabek, Daniel; Bowen, Chris; Abdelmageed, Mostafa; Arafa, Mustafa

    2016-12-01

    Pyroelectric materials have recently received attention for harvesting waste heat owing to their potential to convert temperature fluctuations into useful electrical energy. One of the main challenges in designing pyroelectric energy harvesters is to provide a means to induce a temporal heat variation in a pyroelectric material autonomously from a steady heat source. To address this issue, we propose a new form of wind-driven pyroelectric energy harvester, in which a propeller is set in rotational motion by an incoming wind stream. The speed of the propeller’s shaft is reduced by a gearbox to drive a slider-crank mechanism, in which a pyroelectric material is placed on the slider. Thermal cycling is obtained as the reciprocating slider moves the pyroelectric material across alternative hot and cold zones created by a stationary heat lamp and ambient temperature, respectively. The open-circuit voltage and closed-circuit current are investigated in the time domain at various wind speeds. The device was experimentally tested under wind speeds ranging from 1.1 to 1.6 m s-1 and charged an external 100 nF capacitor through a signal conditioning circuit to demonstrate its effectiveness for energy harvesting. Unlike conventional wind turbines, the energy harvested by the pyroelectric material is decoupled from the wind flow and no mechanical power is drawn from the transmission; hence the system can operate at low wind speeds (<2 m s-1).

  9. The Interplanetary Magnetic Field and Solar Wind Driven Magnetospheric Reconfiguration

    OpenAIRE

    Savov, Eugene

    2002-01-01

    The magnetic disturbances are associated with electric currents as it is well checked at laboratory room scales and described by the Maxwell's equations of electromagnetic field. The analysis of spacecraft observations for more than a quarter of a century failed to provide a self-consistent three-dimensional picture of the solar wind-magnetosphere dynamo generated magnetospheric and ionospheric current systems. The proposed solar wind and the interplanetary magnetic field (IMF) driven reconfi...

  10. Wind/Hybrid Electricity Applications

    Energy Technology Data Exchange (ETDEWEB)

    McDaniel, Lori [Iowa Department of Natural Resources, Des Moines, IA (United States)

    2001-03-01

    Wind energy is widely recognized as the most efficient and cost effective form of new renewable energy available in the Midwest. New utility-scale wind farms (arrays of large turbines in high wind areas producing sufficient energy to serve thousands of homes) rival the cost of building new conventional forms of combustion energy plants, gas, diesel and coal power plants. Wind energy is not subject to the inflationary cost of fossil fuels. Wind energy can also be very attractive to residential and commercial electric customers in high wind areas who would like to be more self-sufficient for their energy needs. And wind energy is friendly to the environment at a time when there is increasing concern about pollution and climate change. However, wind energy is an intermittent source of power. Most wind turbines start producing small amounts of electricity at about 8-10 mph (4 meters per second) of wind speed. The turbine does not reach its rated output until the wind reaches about 26-28 mph (12 m/s). So what do you do for power when the output of the wind turbine is not sufficient to meet the demand for energy? This paper will discuss wind hybrid technology options that mix wind with other power sources and storage devices to help solve this problem. This will be done on a variety of scales on the impact of wind energy on the utility system as a whole, and on the commercial and small-scale residential applications. The average cost and cost-benefit of each application along with references to manufacturers will be given. Emerging technologies that promise to shape the future of renewable energy will be explored as well.

  11. Taylor dispersion in wind-driven current

    Science.gov (United States)

    Li, Gang; Wang, Ping; Jiang, Wei-Quan; Zeng, Li; Li, Zhi; Chen, G. Q.

    2017-12-01

    Taylor dispersion associated with wind-driven currents in channels, shallow lakes and estuaries is essential to hydrological environmental management. For solute dispersion in a wind-driven current, presented in this paper is an analytical study of the evolution of concentration distribution. The concentration moments are intensively derived for an accurate presentation of the mean concentration distribution, up to the effect of kurtosis. The vertical divergence of concentration is then deduced by Gill's method of series expansion up to the fourth order. Based on the temporal evolution of the vertical concentration distribution, the dispersion process in the wind-driven current is concretely characterized. The uniform shear leads to a special symmetrical distribution of mean concentration free of skewness. The non-uniformity of vertical concentration is caused by convection and smeared out gradually by the effect of diffusion, but fails to disappear even at large times.

  12. On continuum driven winds from rotating stars

    OpenAIRE

    Shacham, Tomer; Shaviv, Nir J.

    2012-01-01

    We study the dynamics of continuum driven winds from rotating stars, and develop an approximate analytical model. We then discuss the evolution of stellar angular momentum, and show that just above the Eddington limit, the winds are sufficiently concentrated towards the poles to spin up the star. A twin-lobe structure of the ejected nebula is seen to be a generic consequence of critical rotation. We find that if the pressure in such stars is sufficiently dominated by radiation, an equatorial ...

  13. Directly driven generators for wind power applications

    Energy Technology Data Exchange (ETDEWEB)

    Lampola, P. [Helsinki Univ. of Technology, Espoo (Finland). Lab. of Electromechanics

    1995-12-31

    The article deals with an analysis of directly driven, low-speed wind generators. The generators studied were a permanent-magnet synchronous machine and an asynchronous machine. The machines were compared with a typical generator of a wind power plant. The electromagnetic optimization of the machines was done by the finite element method. The rated power of the generators was 500 kW and the rotational speed was 40 rpm. (author)

  14. Diagnostics of Electric Equipment Windings

    Directory of Open Access Journals (Sweden)

    I. I. Branovitsky

    2007-01-01

    Full Text Available The paper presents methodology and results of the investigations pertaining to study of influence of short-circuited turns on transient electrical processes in electric motor windings. Dependence of their damped speed and value of the difference signal, obtained at reciprocal subtraction of damped oscillation curves in absence and in presence of short-circuited turns, on number of turns in the tested windings. It has been determined that damped oscillation curves, immediately attributed to short-circuited turns, have peak values along temporary axis which are areas of the largest transient process sensitivity to КЗ turns.Methodology for diagnostics of single- and three-phase electric motor windings and also other electric equipment, being realized in DO-1 device, has been developed in the paper. The men­tioned device makes it possible to carry out visual comparison and quantitative analysis of damped oscillation curves in the tested windings with standard ones which are set in the device memory and their difference signals.

  15. Flutter-driven triboelectrification for harvesting wind energy.

    Science.gov (United States)

    Bae, Jihyun; Lee, Jeongsu; Kim, SeongMin; Ha, Jaewook; Lee, Byoung-Sun; Park, YoungJun; Choong, Chweelin; Kim, Jin-Baek; Wang, Zhong Lin; Kim, Ho-Young; Park, Jong-Jin; Chung, U-In

    2014-09-23

    Technologies to harvest electrical energy from wind have vast potentials because wind is one of the cleanest and most sustainable energy sources that nature provides. Here we propose a flutter-driven triboelectric generator that uses contact electrification caused by the self-sustained oscillation of flags. We study the coupled interaction between a fluttering flexible flag and a rigid plate. In doing so, we find three distinct contact modes: single, double and chaotic. The flutter-driven triboelectric generator having small dimensions of 7.5 × 5 cm at wind speed of 15 ms(-1) exhibits high-electrical performances: an instantaneous output voltage of 200 V and a current of 60 μA with a high frequency of 158 Hz, giving an average power density of approximately 0.86 mW. The flutter-driven triboelectric generation is a promising technology to drive electric devices in the outdoor environments in a sustainable manner.

  16. Renewable energy credit driven wind power growth for system reliability

    Energy Technology Data Exchange (ETDEWEB)

    Karki, Rajesh [Power System Research Group, Department of Electrical Engineering, University of Saskatchewan, 57 Campus Dr., Saskatoon, Sask., S7N 5A9 (Canada)

    2007-05-15

    Environmental concerns over electric power generation from conventional sources has led to widespread public support for renewable energy sources. Governments throughout the world have responded by providing various forms of financial incentives to promote power generation from renewable energy sources. The rapid growth of wind power since the last decade has primarily been driven by governmental subsidies. Long-term growth of wind power should, however, be driven by sustainable market mechanisms. A potential solution is to recognize monetary values to the environmental benefits from renewable energy sources, and to specify targets for their growth. The environmental benefits from wind sources can be leveraged to allow market competition of these sources with the less costly conventional generating sources. A probabilistic method to evaluate the impact of renewable energy credit and wind penetration level on the cost and adequacy of power generating systems is presented in this paper. The technique incorporates reliability and economic analysis and is applied to a published test system to illustrate the results and their influence on key system variables. The paper provides useful information to system planners and policy makers on wind energy application in electric power systems. (author)

  17. Katabatic Wind-Driven Exchange in Fjords

    Science.gov (United States)

    Spall, Michael A.; Jackson, Rebecca H.; Straneo, Fiammetta

    2017-10-01

    The general issue of katabatic wind-driven exchange in fjords is considered using an idealized numerical model, theory, and observations. Two regimes are identified. For fjords narrower than a viscous boundary layer width, the exchange is limited by a balance between wind and friction in lateral boundary layers. For the nonlinear viscous parameterization used here, this boundary layer thickness depends on the properties of the fjord, such as stratification and length, as well as on the wind stress and numerical parameters such as grid spacing and an empirical constant. For wider fjords typical of east Greenland, the balance is primarily between wind, the along-fjord pressure gradient, and acceleration, in general agreement with previous two-layer nonrotating theories. It is expected that O(10%) of the surface layer will be flushed out of the fjord by a single wind event. Application of the idealized model to a typical katabatic wind event produces outflowing velocities that are in general agreement with observations in Sermilik Fjord, a large glacial fjord in southeast Greenland. The presence of a sill has only a minor influence on the exchange until the sill penetrates over most of the lower layer thickness, in which cases the exchange is reduced. It is concluded that the multiple katabatic wind events per winter that are experienced by the fjords along east Greenland represent an important mechanism of exchange between the fjord and shelf, with implications for the renewal of warm, salty waters at depth and for the export of glacial freshwater in the upper layer.

  18. Wind-driven stand-alone DFIG with battery and pumped hydro ...

    Indian Academy of Sciences (India)

    Renewable energy electric conversion system; induction generators; wind power generation; energy storage; power converters. ... converter, (ii) wide speed operation of wind-driven DFIG, (iii) reduced battery capacity, (iv) high energy storage using PHSP and (v) availability of continuous power to the isolated loads.

  19. Wind driven saltation: a hitherto overlooked challenge for life on Mars

    DEFF Research Database (Denmark)

    Bak, Ebbe Norskov; Goul, Michael; Rasmussen, Martin

    The Martian surface is a hostile environment characterized by low water availability, low atmospheric pressure and high UV and ionizing radiation. Furthermore, wind-driven saltation leads to abrasion of silicates with a production of reactive surface sites and, through triboelectric charging......, a release of electrical discharges with a concomitant production of reactive oxygen species. While the effects of low water availability, low pressure and radiation have been extensively studied in relation to the habitability of the Martian surface and the preservation of organic biosignatures, the effects...... of wind-driven saltation have hitherto been ignored. In this study, we have investigated the effect of exposing bacteria to wind-abraded silicates and directly to wind-driven saltation on Mars in controlled laboratory simulation experiments. Wind-driven saltation was simulated by tumbling mineral samples...

  20. Research on an Integrated Hydrostatic-Driven Electric Generator with Controllable Load for Renewable Energy Applications

    National Research Council Canada - National Science Library

    Tao Wang; He Wang

    2017-01-01

    A hydrostatic transmission is a promising technology in renewable energy harvesting, such as wind energy and wave energy, where the hydrostatic-driven electric generator is a key energy conversion component...

  1. Wind farm’ producing electric power

    Science.gov (United States)

    Bell, Peter M.

    The nation's first ‘wind farm,’ featuring three of the largest advanced wind turbine systems, is nearing completion. The turbines are the seventh, eighth, and ninth wind turbines to be built under a portion of the federal wind energy program. The first of the three new machines began producing electricity for the Bonneville Power Administration at Goodnoe Hills, near Goldendale, Wash., late last year. The second machine will be fully assembled and begin to generate electricity in February. The third machine is expected to be fully assembled and running late this spring.

  2. Electrical Aspects of Wind Turbines

    DEFF Research Database (Denmark)

    Chen, Zhe; Blaabjerg, Frede

    2009-01-01

    This is the most authoritative single volume on offshore wind power yet published. Distinguished experts, mainly from Europe's leading universities, have contributed a collection of peer reviewed papers on the interfaces between wind power technology and marine engineering. The range of issues...... covered by the book include: wind as a resource; wind power generation; connection to the grid; the marine environment and engineering issues particular to it. This book is essential for academic departments of mechanical engineering/energy engineering/ renewable energy. Offshore wind power generation...

  3. Data-driven wind plant control

    NARCIS (Netherlands)

    Gebraad, P.M.O.

    2014-01-01

    Each wind turbine in a cluster of wind turbines (a wind power plant) can influence the performance of other turbines through the wake that forms downstream of its rotor. The wake has a reduced wind velocity, since the turbine extracts energy from the flow, and the obstruction by the wind turbine

  4. Compatibility Between Electric Components in Wind Farms

    DEFF Research Database (Denmark)

    Holdyk, Andrzej; Holbøll, Joachim; Arana Aristi, Iván

    2011-01-01

    The paper describes a method for investigation of the compatibility between electric components in wind farms by identifying critical resonances at different points of an offshore wind farm (OWF), based on systematic variation of critical parameters. In this way, the design of future OWF can...

  5. Advances in Electrically Driven Thermal Management

    Science.gov (United States)

    Didion, Jeffrey R.

    2017-01-01

    Electrically Driven Thermal Management is a vibrant technology development initiative incorporating ISS based technology demonstrations, development of innovative fluid management techniques and fundamental research efforts. The program emphasizes high temperature high heat flux thermal management required for future generations of RF electronics and power electronic devices. This presentation reviews i.) preliminary results from the Electrohydrodynamic (EHD) Long Term Flight Demonstration launched on STP-H5 payload in February 2017 ii.) advances in liquid phase flow distribution control iii.) development of the Electrically Driven Liquid Film Boiling Experiment under the NASA Microgravity Fluid Physics Program.

  6. Storing wind energy into electrical accumulators

    Science.gov (United States)

    Dordescu, M.; Petrescu, D. I.; Erdodi, G. M.

    2016-12-01

    Shall be determined, in this work, the energy stored in the accumulators electrical, AE, at a wind system operating at wind speeds time-varying. mechanical energy caught in the turbine from the wind, (TV), is transformed into electrical energy by the generator synchronous with the permanent magnets, GSMP. The Generator synchronous with the permanent magnets saws, via a rectifier, energy in a battery AE, finished in a choice of two: variant 1-unregulated rectifier and variant of the 2-controlled rectifier and task adapted. Through simulation determine the differences between the two versions

  7. Electrically driven and electrically tunable quantum light sources

    Science.gov (United States)

    Lee, J. P.; Murray, E.; Bennett, A. J.; Ellis, D. J. P.; Dangel, C.; Farrer, I.; Spencer, P.; Ritchie, D. A.; Shields, A. J.

    2017-02-01

    Compact and electrically controllable on-chip sources of indistinguishable photons are desirable for the development of integrated quantum technologies. We demonstrate that two quantum dot light emitting diodes (LEDs) in close proximity on a single chip can function as a tunable, all-electric quantum light source. Light emitted by an electrically excited driving LED is used to excite quantum dots in the neighbouring diode. The wavelength of the quantum dot emission from the neighbouring driven diode is tuned via the quantum confined Stark effect. We also show that we can electrically tune the fine structure splitting.

  8. Automated electric control of a vertical axis wind turbine in island operation

    OpenAIRE

    Högberg, Lars

    2009-01-01

    At the Division of Electricity at Uppsala University, a wind power concept has been developed. The concept uses a vertical axis wind turbine with a direct driven generator. The turbine has fixed blades, making speed control the only way to regulate power absorption. The speed is controlled with the electric load. The turbine is not self-starting, but can be started using the generator as a motor. In this project, an unsupervised electric system with automatic control is designed and construct...

  9. Price volatility in wind dominant electricity markets

    DEFF Research Database (Denmark)

    Farashbashi-Astaneh, Seyed-Mostafa; Chen, Zhe

    2013-01-01

    electricity markets. High price volatility is unappreciated because it imposes high financial risk levels to both electricity consumers and producers. Additionally high price variations impede tracking price signals by consumers in future smart grid and jeopardize implementation of demand response concepts......High penetration of intermittent renewable energy sources causes price volatility in future electricity markets. This is specially the case in European countries that plan high penetration levels. This highlights the necessity for revising market regulations and mechanisms in accordance....... The main contribution of this paper is to quantify volatility patterns of electricity price, as penetration level of wind power increases. Results explain a direct relationship between wind penetration and electricity price volatility in a quantitative manner....

  10. Towards Data-Driven Control for Modern Wind Turbines

    NARCIS (Netherlands)

    Houtzager, I.

    2011-01-01

    Further developments in data-driven control techniques for the load reduction of modern wind turbines can achieve an increased lifetime of components and make the scaling to larger rotor diameters possible, and therefore improve the cost effectiveness of modern wind turbines. Also the success of

  11. Mechanics of interrill erosion with wind-driven rain

    NARCIS (Netherlands)

    Erpul, G.; Gabriels, D.; Norton, L.D.; Flanagan, D.C.; Huang, C.; Visser, S.M.

    2013-01-01

    The vector physics of wind-driven rain (WDR) differs from that of wind-free rain, and the interrill soil detachment equations in the Water Erosion Prediction Project (WEPP) model were not originally developed to deal with this phenomenon. This article provides an evaluation of the performance of the

  12. Mechanics of Interrill Erosion with Wind-Driven Rain (WDR)

    Science.gov (United States)

    This article provides an evaluation analysis for the performance of the interrill component of the Water Erosion Prediction Project (WEPP) model for Wind-Driven Rain (WDR) events. The interrill delivery rates (Di) were collected in the wind tunnel rainfall simulator facility of the International Cen...

  13. Mechanics of interrill erosion with wind-driven rain

    Science.gov (United States)

    The vector physics of wind-driven rain (WDR) differs from that of wind-free rain, and the interrill soil detachment equations in the Water Erosion Prediction Project (WEPP) model were not originally developed to deal with this phenomenon. This article provides an evaluation of the performance of the...

  14. Electrically Driven Technologies for Radioactive Aerosol Abatement

    Energy Technology Data Exchange (ETDEWEB)

    David W. DePaoli; Ofodike A. Ezekoye; Costas Tsouris; Valmor F. de Almeida

    2003-01-28

    The purpose of this research project was to develop an improved understanding of how electriexecy driven processes, including electrocoalescence, acoustic agglomeration, and electric filtration, may be employed to efficiently treat problems caused by the formation of aerosols during DOE waste treatment operations. The production of aerosols during treatment and retrieval operations in radioactive waste tanks and during thermal treatment operations such as calcination presents a significant problem of cost, worker exposure, potential for release, and increased waste volume.

  15. Global potential for wind-generated electricity

    Science.gov (United States)

    Lu, Xi; McElroy, Michael B.; Kiviluoma, Juha

    2009-01-01

    The potential of wind power as a global source of electricity is assessed by using winds derived through assimilation of data from a variety of meteorological sources. The analysis indicates that a network of land-based 2.5-megawatt (MW) turbines restricted to nonforested, ice-free, nonurban areas operating at as little as 20% of their rated capacity could supply >40 times current worldwide consumption of electricity, >5 times total global use of energy in all forms. Resources in the contiguous United States, specifically in the central plain states, could accommodate as much as 16 times total current demand for electricity in the United States. Estimates are given also for quantities of electricity that could be obtained by using a network of 3.6-MW turbines deployed in ocean waters with depths <200 m within 50 nautical miles (92.6 km) of closest coastlines. PMID:19549865

  16. A proposed national wind power R and D program. [offshore wind power system for electric energy supplies

    Science.gov (United States)

    Heronemus, W.

    1973-01-01

    An offshore wind power system is described that consists of wind driven electrical dc generators mounted on floating towers in offshore waters. The output from the generators supplies underwater electrolyzer stations in which water is converted into hydrogen and oxygen. The hydrogen is piped to shore for conversion to electricity in fuel cell stations. It is estimated that this system can produce 159 x 10 to the ninth power kilowatt-hours per year. It is concluded that solar energy - and that includes wind energy - is the only way out of the US energy dilemma in the not too distant future.

  17. Nucleosynthesis in Early Neutrino Driven Winds

    Energy Technology Data Exchange (ETDEWEB)

    Hoffman, R; Fisker, J; Pruet, J; Woosley, S; Janka, H; Buras, R

    2008-01-09

    Two recent issues related to nucleosynthesis in early proton-rich neutrino winds are investigated. In the first part we investigate the effect of nuclear physics uncertainties on the synthesis of {sup 92}Mo and {sup 94}Mo. Based on recent experimental results, we find that the proton rich winds of the model investigated here can not be the only source of the solar abundance of {sup 92}Mo and {sup 94}Mo. In the second part we investigate the nucleosynthesis from neutron rich bubbles and show that they do not contribute to the nucleosynthesis integrated over both neutron and proton-rich bubbles and proton-rich winds.

  18. Pricing Electricity in Pools With Wind Producers

    DEFF Research Database (Denmark)

    Morales González, Juan Miguel; Conejo, A. J.; Kai Liu

    2012-01-01

    This paper considers an electricity pool that includes a significant number of wind producers and is cleared through a network-constrained auction, one day in advance and on an hourly basis. The hourly auction is formulated as a two-stage stochastic programming problem, where the first stage repr...

  19. Radiation Driven Wind Solutions and Applications

    Science.gov (United States)

    Curé, M.

    2016-11-01

    The standard modified-CAK equation of motion is a non-linear differential equation that possesses many singular points and therefore many solutions. Apart from the standard solution, we have found three other physical solutions: i) when the rotational velocity is higher than 3/4 of the critical rotational speed; ii) when there is a high ionization change throughout the wind; and iii) when the k line force parameter is very high (k is the fraction of the total stellar flux which would be blocked in the photosphere if all lines were optically thick). We also show some applications of these solutions, e.g., the wind of a B[e] supergiant, the oblate wind of a Be star, and the winds of BA supergiants. Furthermore, we calculate synthetic spectra with FASTWIND, where we have used our new hydrodynamical solutions as input to the code.

  20. Use of wind turbines to generate electricity for highway buildings.

    Science.gov (United States)

    1983-01-01

    To determine the feasibility of using wind turbines to generate electrical power, measurements of wind speeds were made for a period of one year at three installations of the Virginia Department of Highways and Transportation. Unfortunately, the wind...

  1. Advances in Optimizing Weather Driven Electric Power Systems.

    Science.gov (United States)

    Clack, C.; MacDonald, A. E.; Alexander, A.; Dunbar, A. D.; Xie, Y.; Wilczak, J. M.

    2014-12-01

    The importance of weather-driven renewable energies for the United States (and global) energy portfolio is growing. The main perceived problems with weather-driven renewable energies are their intermittent nature, low power density, and high costs. The National Energy with Weather System Simulator (NEWS) is a mathematical optimization tool that allows the construction of weather-driven energy sources that will work in harmony with the needs of the system. For example, it will match the electric load, reduce variability, decrease costs, and abate carbon emissions. One important test run included existing US carbon-free power sources, natural gas power when needed, and a High Voltage Direct Current power transmission network. This study shows that the costs and carbon emissions from an optimally designed national system decrease with geographic size. It shows that with achievable estimates of wind and solar generation costs, that the US could decrease its carbon emissions by up to 80% by the early 2030s, without an increase in electric costs. The key requirement would be a 48 state network of HVDC transmission, creating a national market for electricity not possible in the current AC grid. These results were found without the need for storage. Further, we tested the effect of changing natural gas fuel prices on the optimal configuration of the national electric power system. Another test that was carried out was an extension to global regions. The extension study shows that the same properties found in the US study extend to the most populous regions of the planet. The extra test is a simplified version of the US study, and is where much more research can be carried out. We compare our results to other model results.

  2. Multi-winding homopolar electric machine

    Science.gov (United States)

    Van Neste, Charles W

    2012-10-16

    A multi-winding homopolar electric machine and method for converting between mechanical energy and electrical energy. The electric machine includes a shaft defining an axis of rotation, first and second magnets, a shielding portion, and a conductor. First and second magnets are coaxial with the shaft and include a charged pole surface and an oppositely charged pole surface, the charged pole surfaces facing one another to form a repulsive field therebetween. The shield portion extends between the magnets to confine at least a portion of the repulsive field to between the first and second magnets. The conductor extends between first and second end contacts and is toroidally coiled about the first and second magnets and the shield portion to develop a voltage across the first and second end contacts in response to rotation of the electric machine about the axis of rotation.

  3. Instabilities in electrically driven rotating MHD layers

    Science.gov (United States)

    Mistrangelo, C.; Bühler, L.

    2017-07-01

    Flows of electrically conducting fluids exposed to intense magnetic fields exhibit a common feature i.e. the formation of uniform cores in which electromagnetic forces are dominant. Cores are separated from each other by thin layers that extend along magnetic field lines. Across these parallel layers strong gradients of flow variables are present, which can lead to the onset of instabilities and non-linear flow transitions. In this work we investigate dynamics and stability issues of rotating parallel layers driven by electromagnetic forces caused by the interaction of injected electric currents with an applied magnetic field. The geometry considered consists of two coaxial circular electrodes used for current injection. They are placed in parallel electrically insulating planes perpendicular to a uniform magnetic field. The basic axisymmetric steady state flow, characterized by a rotating velocity jet confined in a parallel layer that connects the rims of the electrodes, is rather well understood. By increasing the driving current above a critical value the basic flow becomes unstable and undergoes a sequence of supercritical bifurcations.

  4. Wind-driven estuarine turbidity maxima in Mandovi Estuary, central ...

    Indian Academy of Sciences (India)

    Transect stations reveal that the SPM at sea-end stations of the estuary are at least two orders of ... and wind-driven waves and currents seem to have acted effectively at the mouth of the estuary in developing .... Location map of the Mandovi River and sampling stations in the river channel. RS – regular station. Numbers.

  5. Conceptual models of the wind-driven and thermohaline circulation

    NARCIS (Netherlands)

    Drijfhout, S.S.; Marshall, D.P.; Dijkstra, H.A.

    2013-01-01

    Conceptual models are a vital tool for understanding the processes that maintain the global ocean circulation, both in nature and in complex numerical ocean models. In this chapter we provide a broad overview of our conceptual understanding of the wind-driven circulation, the thermohaline

  6. An Overview of Wind-Driven Rovers for Planetary Exploration

    Science.gov (United States)

    Hajos, Gregory A.; Jones, Jack A.; Behar, Alberto; Dodd, Micheal

    2005-01-01

    The use of in-situ propulsion is considered enabling technology for long duration planetary surface missions. Most studies have focused on stored energy from chemicals extracted from the soil or the use of soil chemicals to produce photovoltaic arrays. An older form of in-situ propulsion is the use of wind power. Recent studies have shown potential for wind driven craft for exploration of Mars, Titan and Venus. The power of the wind, used for centuries to power wind mills and sailing ships, is now being applied to modern land craft. Efforts are now underway to use the wind to push exploration vehicles on other planets and moons in extended survey missions. Tumbleweed rovers are emerging as a new type of wind-driven science platform concept. Recent investigations by the National Aeronautics and Space Administration (NASA) and Jet Propulsion Laboratory (JPL) indicate that these light-weight, mostly spherical or quasi-spherical devices have potential for long distance surface exploration missions. As a power boat has unique capabilities, but relies on stored energy (fuel) to move the vessel, the Tumbleweed, like the sailing ships of the early explorers on earth, uses an unlimited resource the wind to move around the surface of Mars. This has the potential to reduce the major mass drivers of robotic rovers as well as the power generation and storage systems. Jacques Blamont of JPL and the University of Paris conceived the first documented Mars wind-blown ball in 1977, shortly after the Viking landers discovered that Mars has a thin CO2 atmosphere with relatively strong winds. In 1995, Jack Jones, et al, of JPL conceived of a large wind-blown inflated ball for Mars that could also be driven and steered by means of a motorized mass hanging beneath the rolling axis of the ball. A team at NASA Langley Research Center started a biomimetic Tumbleweed design study in 1998. Wind tunnel and CFD analysis were applied to a variety of concepts to optimize the aerodynamic

  7. Repetitive control of electrically driven robot manipulators

    Science.gov (United States)

    Fateh, Mohammad Mehdi; Ahsani Tehrani, Hojjat; Karbassi, Seyed Mehdi

    2013-04-01

    This article presents a novel robust discrete repetitive control of electrically driven robot manipulators for tracking of a periodic trajectory. We propose a novel model, which presents the highly non-linear dynamics of robot manipulator in the form of linear discrete-time time-varying system. Based on the proposed model, we develop a two-term control law. The first term is an ordinary time-optimal and minimum-norm (TOMN) control by employing parametric controllers to guarantee stability. The second term is a novel robust control to improve the control performance in the face of uncertainties. The robust control estimates and compensates uncertainties including the parametric uncertainty, unmodelled dynamics and external disturbances. Performance of the proposed method is compared with two discrete methods, namely the TOMN control and an adaptive iterative learning (AIL) control. Simulation results confirm superiority of the proposed method in terms of the convergence speed and precision.

  8. Gas-fired wind power and electric hydrogen

    NARCIS (Netherlands)

    Hemmes, K.

    2006-01-01

    In the seemingly endless discussions about the pros and cons of wind power even its advocates have to agree that though wind can fly, with offshore wind farms soon to become reality, this only exacerbates the problem of the winds changeability. Even now the major producers of electricity and power

  9. Hydrogel Actuation by Electric Field Driven Effects

    Science.gov (United States)

    Morales, Daniel Humphrey

    Hydrogels are networks of crosslinked, hydrophilic polymers capable of absorbing and releasing large amounts of water while maintaining their structural integrity. Polyelectrolyte hydrogels are a subset of hydrogels that contain ionizable moieties, which render the network sensitive to the pH and the ionic strength of the media and provide mobile counterions, which impart conductivity. These networks are part of a class of "smart" material systems that can sense and adjust their shape in response to the external environment. Hence, the ability to program and modulate hydrogel shape change has great potential for novel biomaterial and soft robotics applications. We utilized electric field driven effects to manipulate the interaction of ions within polyelectrolyte hydrogels in order to induce controlled deformation and patterning. Additionally, electric fields can be used to promote the interactions of separate gel networks, as modular components, and particle assemblies within gel networks to develop new types of soft composite systems. First, we present and analyze a walking gel actuator comprised of cationic and anionic gel legs attached by electric field-promoted polyion complexation. We characterize the electro-osmotic response of the hydrogels as a function of charge density and external salt concentration. The gel walkers achieve unidirectional motion on flat elastomer substrates and exemplify a simple way to move and manipulate soft matter devices in aqueous solutions. An 'ionoprinting' technique is presented with the capability to topographically structure and actuate hydrated gels in two and three dimensions by locally patterning ions induced by electric fields. The bound charges change the local mechanical properties of the gel to induce relief patterns and evoke localized stress, causing rapid folding in air. The ionically patterned hydrogels exhibit programmable temporal and spatial shape transitions which can be tuned by the duration and/or strength of

  10. Offshore wind farm electrical cable layout optimization

    Science.gov (United States)

    Pillai, A. C.; Chick, J.; Johanning, L.; Khorasanchi, M.; de Laleu, V.

    2015-12-01

    This article explores an automated approach for the efficient placement of substations and the design of an inter-array electrical collection network for an offshore wind farm through the minimization of the cost. To accomplish this, the problem is represented as a number of sub-problems that are solved in series using a combination of heuristic algorithms. The overall problem is first solved by clustering the turbines to generate valid substation positions. From this, a navigational mesh pathfinding algorithm based on Delaunay triangulation is applied to identify valid cable paths, which are then used in a mixed-integer linear programming problem to solve for a constrained capacitated minimum spanning tree considering all realistic constraints. The final tree that is produced represents the solution to the inter-array cable problem. This method is applied to a planned wind farm to illustrate the suitability of the approach and the resulting layout that is generated.

  11. Experimental wind-driven rain erosion study on agricultural soils

    Science.gov (United States)

    Marzen, Miriam; Iserloh, Thomas; Brings, Christine; Fister, Wolfgang; Seeger, Manuel; Ries, Johannes B.

    2014-05-01

    Wind is potentially capable to considerably increase soil erosion by rain drops. In contrast to laboratory experiments, in-situ experiments enable the measurement of soil erosion by wind and rain including the reactions of relatively intact soil surfaces and a complete body of soil. The Portable Wind and Rainfall Simulator of Trier University was applied on winter cereal fields to measure rain erosion on agricultural areas with and without the influence of wind. The test areas are situated near Pamplona, Navarre and recognized to be representative for large parts of northern Spain concerning soil, land use and climate. The soil surfaces on the fields were ploughed and sparsely covered by recently sowed winter cereals. The soil water content was close to saturation due to long lasting rainfall. Runoff was medium to high with runoff-coefficients ranging from 26 to 100%. The eroded material from rainfall simulations ranged from 14.5 to 42.5 g m² / 30min. The eroded material from wind-driven rain ranged from 28.1 to 47.3 g m² / 30 min. Compared to windless rainfall, the wind-driven rain increased erosion of soil material up to 82.2%. In one case, the eroded material decreased by 18.3%. The results indicate a strong influence of wind on rain erosion on recently seeded agricultural soils. Wind influence can be an important aspect for the general assessment of sheet erosion and supports the finding that a neglect of this factor might lead to severe underestimation of soil loss.

  12. Wind-Driven Ecological Flow Regimes Downstream from Hydropower Dams

    Science.gov (United States)

    Kern, J.; Characklis, G. W.

    2012-12-01

    Conventional hydropower can be turned on and off quicker and less expensively than thermal generation (coal, nuclear, or natural gas). These advantages enable hydropower utilities to respond to rapid fluctuations in energy supply and demand. More recently, a growing renewable energy sector has underlined the need for flexible generation capacity that can complement intermittent renewable resources such as wind power. While wind power entails lower variable costs than other types of generation, incorporating it into electric power systems can be problematic. Due to variable and unpredictable wind speeds, wind power is difficult to schedule and must be used when available. As a result, integrating large amounts of wind power into the grid may result in atypical, swiftly changing demand patterns for other forms of generation, placing a premium on sources that can be rapidly ramped up and down. Moreover, uncertainty in wind power forecasts will stipulate increased levels of 'reserve' generation capacity that can respond quickly if real-time wind supply is less than expected. These changes could create new hourly price dynamics for energy and reserves, altering the short-term financial signals that hydroelectric dam operators use to schedule water releases. Traditionally, hourly stream flow patterns below hydropower dams have corresponded in a very predictable manner to electricity demand, whose primary factors are weather (hourly temperature) and economic activity (workday hours). Wind power integration has the potential to yield more variable, less predictable flows at hydro dams, flows that at times could resemble reciprocal wind patterns. An existing body of research explores the impacts of standard, demand-following hydroelectric dams on downstream ecological flows; but weighing the benefits of increased reliance on wind power against further impacts to ecological flows may be a novel challenge for the environmental community. As a preliminary step in meeting this

  13. Wind-electric ice making investigation

    Energy Technology Data Exchange (ETDEWEB)

    Holz, R.; Drouilhet, S.; Gevorgian, V.

    1998-07-01

    The village power group at the National Renewable Energy Laboratory (NREL) has been researching the most practical and cost-effective means for producing ice from off-grid wind-electric power systems since 1993. The first phase of the project demonstrated that commercial vapor-compression ice makers could operate effectively when powered by a variable speed permanent magnet wind generator. In the second phase of the project, steady-state and dynamic numerical models of these systems were developed and experimentally validated. The third phase of the project was thorough steady-state and dynamic testing of a commercial 1.1 ton ice maker unit powered by a commercial 12 kW wind turbine alternator on an NREL dynamometer test stand. With the data from phases 1--3 an economic feasibility analysis was performed. It is hoped that continued development, and eventually commercialization, of this concept will take place in the private sector in the form of small business partnerships.

  14. Electric solar wind sail mass budget model

    Directory of Open Access Journals (Sweden)

    P. Janhunen

    2013-02-01

    Full Text Available The electric solar wind sail (E-sail is a new type of propellantless propulsion system for Solar System transportation, which uses the natural solar wind to produce spacecraft propulsion. The E-sail consists of thin centrifugally stretched tethers that are kept charged by an onboard electron gun and, as such, experience Coulomb drag through the high-speed solar wind plasma stream. This paper discusses a mass breakdown and a performance model for an E-sail spacecraft that hosts a mission-specific payload of prescribed mass. In particular, the model is able to estimate the total spacecraft mass and its propulsive acceleration as a function of various design parameters such as the number of tethers and their length. A number of subsystem masses are calculated assuming existing or near-term E-sail technology. In light of the obtained performance estimates, an E-sail represents a promising propulsion system for a variety of transportation needs in the Solar System.

  15. Local scale structures in Earth's thermospheric winds and their consequences for wind driven transport

    Science.gov (United States)

    Dhadly, Manbharat Singh

    In the traditional picture of Earth's upper thermosphere (~190--300 km), it is widely presumed that its convective stability and enormous kinematic viscosity attenuate wind gradients, and hence smooth out any structure present in the wind over scale size of several hundreds of kilometers. However, several independent experimental studies have shown that observed upper thermospheric wind fields at high latitudes contain stronger than expected local-scale spatial structures. The motivation of this dissertation is to investigate how the resulting local-scale gradients would distort neutral air masses and complicate thermospheric wind transport. To achieve this goal, we examined the behavior of a simple parameter that we refer to as the "distortion gradient". It incorporates all of the wind field's departures from uniformity, and is thus capable of representing all resulting contributions to the distortion or mixing of air masses. Climatological analysis of the distortion gradient using 2010, 2011, and 2012 wind data from the All-sky Scanning Doppler Imager (SDI) located at Poker Flat (65.12N, 147.47W) revealed the diurnal and seasonal trends in distortion of thermospheric masses. Distortion was observed to be dependent on geomagnetic activity and orientation of the interplanetary magnetic field. To understand the time-cumulative influence of these local-scale non-uniformities on thermospheric wind driven transport, time-resolved two-dimensional maps of the thermospheric vector wind fields were used to infer forward and backward air parcel trajectories. Tracing air parcel trajectories through a given geographic location indicates where they came from previously, and where they will go in the future. Results show that wind driven transport is very sensitive to small-scale details of the wind field. Any local-scale spatial wind gradients can significantly complicate air parcel trajectories. Transport of thermospheric neutral species in the presence of the local

  16. Kinetic instabilities in the solar wind driven by temperature anisotropies

    Science.gov (United States)

    Yoon, Peter H.

    2017-12-01

    The present paper comprises a review of kinetic instabilities that may be operative in the solar wind, and how they influence the dynamics thereof. The review is limited to collective plasma instabilities driven by the temperature anisotropies. To limit the scope even further, the discussion is restricted to the temperature anisotropy-driven instabilities within the model of bi-Maxwellian plasma velocity distribution function. The effects of multiple particle species or the influence of field-aligned drift will not be included. The field-aligned drift or beam is particularly prominent for the solar wind electrons, and thus ignoring its effect leaves out a vast portion of important physics. Nevertheless, for the sake of limiting the scope, this effect will not be discussed. The exposition is within the context of linear and quasilinear Vlasov kinetic theories. The discussion does not cover either computer simulations or data analyses of observations, in any systematic manner, although references will be made to published works pertaining to these methods. The scientific rationale for the present analysis is that the anisotropic temperatures associated with charged particles are pervasively detected in the solar wind, and it is one of the key contemporary scientific research topics to correctly characterize how such anisotropies are generated, maintained, and regulated in the solar wind. The present article aims to provide an up-to-date theoretical development on this research topic, largely based on the author's own work.

  17. Wind Power in Electrical Distribution Systems

    DEFF Research Database (Denmark)

    Chen, Zhe

    2013-01-01

    Recent years, wind power is experiencing a rapid growth, large number of wind turbines/wind farms have been installed and connected to power systems. In addition to the large centralised wind farms connected to transmission grids, many distributed wind turbines and wind farms are operated...... as distributed generators in distribution systems. This paper discusses the issues of wind turbines in distribution systems. Wind power conversion systems briefly introduced, the basic features and technical characteristics of distributed wind power system are described, and the main technical demands...

  18. assessment of wind energy potential for electricity generation in ...

    African Journals Online (AJOL)

    Wind energy is proposed as an alternative source of electricity to fossil fuel generators ... it is very variable compared to other sources of energy. It is also more sensitive to variations with topography and weather patterns compared to solar energy. ... A study on wind speed pattern and the available wind power in Tanzania.

  19. Wind energy for electricity generation in Sri Lanka

    Energy Technology Data Exchange (ETDEWEB)

    Fernando, W.J.

    1988-01-01

    Different aspects of the island Sri Lanka are discussed in relation to the use of wind energy to generate electric power. The electricity demand and supply are dealt with as well as geo-climatic features. Wind resources in different parts of Sri Lanka are determined. Further study is needed to achieve more data on wind potential and wind speeds. Finally a case study is discussed, carried out to assess the feasibility of integration of wind and hydro resources in combination to meet a predetermined load to be used in an optimal configuration. 7 figs., 1 tab.

  20. Electric Control Substituting Pitch Control for Large Wind Turbines

    Directory of Open Access Journals (Sweden)

    Jon Kjellin

    2013-01-01

    turbine has fixed pitch and is only controlled electrically accommodated by passive stall of the blades. By electrically controlling the generator rotational speed with the inverter, passive stall regulation is enabled. The first results on experimental verification of stall regulation in gusty wind speeds are presented. The experiments show that the control system can keep the turbine rotational speed constant even at very gusty winds. It is concluded that electrical control accommodated by passive stall is sufficient as control of the wind turbine even at high wind speeds and can substitute mechanical control such as blade pitch.

  1. Electric Generators and their Control for Large Wind Turbines

    DEFF Research Database (Denmark)

    Boldea, Ion; Tutelea, Lucian; Rallabandi, Vandana

    2017-01-01

    The electric generator and its power electronics interface for wind turbines (WTs) have evolved rapidly toward higher reliability and reduced cost of energy in the last 40 years. This chapter describes the up-to-date electric generators existing in the wind power industry, namely, the doubly fed...

  2. High Penetrated Wind Farm Impacts on the Electricity Price

    DEFF Research Database (Denmark)

    Haji Bashi, Mazaher; Yousefi, G. R.; Bak, Claus Leth

    2016-01-01

    Energy trading policies, intermittency of wind farm output power, low marginal cost of the production, are the key factors that cause the wind farms to be effective on the electricity price. In this paper, the Danish electricity market is studied as a part of Nord Pool. Considering the completely...... fossil fuel free overview in Danish energy policies, and the currently great share of wind power (more than 100% for some hours) in supplying the load, it is an interesting benchmark for the future electricity markets. Negative prices, price spikes, and price volatility are considered as the main effects...... of the high penetrated wind farm integration into electricity markets. Then, stochastic programming approach is employed to compare the volume of trades for a typical wind farm in a high and low wind penetrated market. Although increasing price spikes and volatility was reported in the literature...

  3. Self-similar Theory of Wind-driven Sea

    Science.gov (United States)

    Zakharov, V. E.

    2015-12-01

    More than two dozens field experiments performed in the ocean and on the lakes show that the fetch-limited growth of dimensionless energy and dimensionless peak frequency is described by powerlike functions of the dimensionless fetch. Moreover, the exponents of these two functions are connected with a proper accuracy by the standard "magic relation", 10q-2p=1. Recent massive numerical experiments as far as experiments in wave tanks also confirm this magic relation. All these experimental facts can be interpreted in a framework of the following simple theory. The wind-driven sea is described by the "conservative" Hasselmann kinetic equation. The source terms, wind input and white-capping dissipation, play a secondary role in comparison with the nonlinear term Snl that is responsible for the four-wave resonant interaction. This equation has four-parameter family of self-similar solutions. The magic relation holds for all numbers of this family. This fact gives strong hope that development of self-consistent analytic theory of wind-driven sea is quite realizable task.

  4. ON CONTINUUM-DRIVEN WINDS FROM ROTATING STARS

    Energy Technology Data Exchange (ETDEWEB)

    Shacham, Tomer; Shaviv, Nir J. [Racah Institute of Physics, Hebrew University of Jerusalem, Jerusalem 91904 (Israel)

    2012-10-01

    We study the dynamics of continuum-driven winds from rotating stars and develop an approximate analytical model. We then discuss the evolution of stellar angular momentum, and show that just above the Eddington limit, the winds are sufficiently concentrated toward the poles to spin-up the star. A twin-lobe structure of the ejected nebula is seen to be a generic consequence of critical rotation. We find that if the pressure in such stars is sufficiently dominated by radiation, an equatorial ejection of mass will occur during eruptions. These results are then applied to {eta}-Carinae. We show that if it began its life with a high enough angular momentum, the present-day wind could have driven the star toward critical rotation, if it is the dominant mode of mass loss. We find that the shape and size of the Homunculus nebula, as given by our model, agree with recent observations. Moreover, the contraction expected due to the sudden increase in luminosity at the onset of the Great Eruption explains the equatorial 'skirt' as well.

  5. On Continuum-driven Winds from Rotating Stars

    Science.gov (United States)

    Shacham, Tomer; Shaviv, Nir J.

    2012-10-01

    We study the dynamics of continuum-driven winds from rotating stars and develop an approximate analytical model. We then discuss the evolution of stellar angular momentum, and show that just above the Eddington limit, the winds are sufficiently concentrated toward the poles to spin-up the star. A twin-lobe structure of the ejected nebula is seen to be a generic consequence of critical rotation. We find that if the pressure in such stars is sufficiently dominated by radiation, an equatorial ejection of mass will occur during eruptions. These results are then applied to η-Carinae. We show that if it began its life with a high enough angular momentum, the present-day wind could have driven the star toward critical rotation, if it is the dominant mode of mass loss. We find that the shape and size of the Homunculus nebula, as given by our model, agree with recent observations. Moreover, the contraction expected due to the sudden increase in luminosity at the onset of the Great Eruption explains the equatorial "skirt" as well.

  6. Equilibrium pricing in electricity markets with wind power

    Science.gov (United States)

    Rubin, Ofir David

    Estimates from the World Wind Energy Association assert that world total wind power installed capacity climbed from 18 Gigawatt (GW) to 152 GW from 2000 to 2009. Moreover, according to their predictions, by the end of 2010 global wind power capacity will reach 190 GW. Since electricity is a unique commodity, this remarkable expansion brings forward several key economic questions regarding the integration of significant amount of wind power capacity into deregulated electricity markets. The overall dissertation objective is to develop a comprehensive theoretical framework that enables the modeling of the performance and outcome of wind-integrated electricity markets. This is relevant because the state of knowledge of modeling electricity markets is insufficient for the purpose of wind power considerations. First, there is a need to decide about a consistent representation of deregulated electricity markets. Surprisingly, the related body of literature does not agree on the very economic basics of modeling electricity markets. That is important since we need to capture the fundamentals of electricity markets before we introduce wind power to our study. For example, the structure of the electric industry is a key. If market power is present, the integration of wind power has large consequences on welfare distribution. Since wind power uncertainty changes the dynamics of information it also impacts the ability to manipulate market prices. This is because the quantity supplied by wind energy is not a decision variable. Second, the intermittent spatial nature of wind over a geographical region is important because the market value of wind power capacity is derived from its statistical properties. Once integrated into the market, the distribution of wind will impact the price of electricity produced from conventional sources of energy. Third, although wind power forecasting has improved in recent years, at the time of trading short-term electricity forwards, forecasting

  7. Wind driven saltation: a hitherto overlooked challenge for life on Mars

    Science.gov (United States)

    Bak, Ebbe; Goul, Michael; Rasmussen, Martin; Moeller, Ralf; Nørnberg, Per; Knak Jensen, Svend; Finster, Kai

    2017-04-01

    The Martian surface is a hostile environment characterized by low water availability, low atmospheric pressure and high UV and ionizing radiation. Furthermore, wind-driven saltation leads to abrasion of silicates with a production of reactive surface sites and, through triboelectric charging, a release of electrical discharges with a concomitant production of reactive oxygen species. While the effects of low water availability, low pressure and radiation have been extensively studied in relation to the habitability of the Martian surface and the preservation of organic biosignatures, the effects of wind-driven saltation have hitherto been ignored. In this study, we have investigated the effect of exposing bacteria to wind-abraded silicates and directly to wind-driven saltation on Mars in controlled laboratory simulation experiments. Wind-driven saltation was simulated by tumbling mineral samples in a Mars-like atmosphere in sealed quartz ampoules. The effects on bacterial survival and structure were evaluated by colony forming unit counts in combination with scanning electron microscopy, quantitative polymerase chain reaction and life/dead-staining with flow cytometry. The viability of vegetative cells of P. putida, B. subtilis and D. radiodurans in aqueous suspensions was reduced by more than 99% by exposure to abraded basalt, while the viability of B. subtilis endospores was unaffected. B. subtilis mutants lacking different spore components were likewise highly resistant to the exposure to abraded basalt, which indicates that the resistance of spores is not associated with any specific spore component. We found a significant but reduced effect of abraded quartz and we suggest that the stress effect of abraded silicates is induced by a production of reactive oxygen species and hydroxyl radicals produced by Fenton-like reactions in the presence of transition metals. Direct exposure to simulated saltation had a dramatic effect on both D. radiodurans cells and B

  8. Incorporating the Variability of Wind Power with Electric Heat Pumps

    Directory of Open Access Journals (Sweden)

    Hongyu Long

    2011-10-01

    Full Text Available With the mass introduction of wind power in Northern China, wind power variability has appeared. In this article, both existing electric heat pumps (EHPs and coal-fired combined heat and power (CHP facilities, which are generally equipped with extraction-condensing steam turbines coupled with district heating for space heating purposes, are proposed to incorporate the variability of wind power equivalently. The authors’ proposal arises from the facts that: (1 EHPs can provide space heating in the domestic sector with little thermal comfort change (e.g., energy carriers for space heating purposes can be switched from heating water to electricity; (2 coal-fired CHP units in Northern China can usually generate more electrical power corresponding to a shaved thermal power production. Thus, it is suggested that heating water from CHP units be shaved when the wind generation is low due to the variability of wind power, so as to enable more electrical power production and compensate for the corresponding insufficient wind generation. Following this, in the future and for some space heating loads at appropriate distances, electricity used as energy carrier should be converted by electric heat pumps for space heating. Thus, more electricity consumption will be achieved so as to avoid wasting wind power when the wind generation it is high. A numerical simulation is performed in order to illustrate the authors’ proposal. It is shown that the impact of variability of wind generation can be equivalently reduced to a great extent, which enable more wind power integration instead of curtailment and potential energy conservation. Moreover, in contrast to before, both the thermal and electrical power of coal-fired CHP units are no longer constants. In addition, the ratio of electrical to thermal power of CHP units is no longer constant either, and results in less energy consumption compared with fixed ratio. Finally, electricity consumed by end users’ EHPs

  9. On the nonlinear evolution of wind-driven gravity waves

    Science.gov (United States)

    Alexakis, A.; Calder, A. C.; Dursi, L. J.; Rosner, R.; Truran, J. W.; Fryxell, B.; Zingale, M.; Timmes, F. X.; Olson, K.; Ricker, P.

    2004-09-01

    We present a study of wind-driven nonlinear interfacial gravity waves using numerical simulations in two dimensions. We consider a case relevant to mixing phenomenon in astrophysical events such as novae in which the density ratio is approximately 1:10. Our physical setup follows the proposed mechanism of Miles [J. Fluid Mech. 3, 185 (1957)] for the amplification of such waves. Our results show good agreement with linear predictions for the growth of the waves. We explore how the wind strength affects the wave dynamics and the resulting mixing in the nonlinear stage. We identify two regimes of mixing, namely, the overturning and the cusp-breaking regimes. The former occurs when the wind is strong enough to overcome the gravitational potential barrier and overturn the wave. This result is in agreement with the common notion of turbulent mixing in which density gradients are increased to diffusion scales by the stretching of a series of vortices. In the latter case, mixing is the result of cusp instabilities. Although the wind is not strong enough to overturn the wave in this case, it can drive the wave up to a maximum amplitude where a singular structure at the cusp of the wave forms. Such structures are subject to various instabilities near the cusp that result in breaking the cusp. Mixing then results from these secondary instabilities and the spray-like structures that appear as a consequence of the breaking.

  10. Survey of wind power potential for wind-based electricity at ...

    African Journals Online (AJOL)

    The potential for wind-generated electricity is examined using 22 months wind data collected from a prospective site located in the southern highlands of Tanzania. While the data for the year 2001 was from March to December that of 2002 was for all the twelve months of the year. Characteristics of monthly and annual wind ...

  11. Wind-driven marine phytoplank blooms: Satellite observation and analysis

    Science.gov (United States)

    Tang, DanLing

    2016-07-01

    Algal bloom is defined as a rapid increase or accumulation in biomass in an aquatic system. It not only can increase the primary production but also could result in negative ecological consequence, e.g.,Harmful Algal Blooms (HABs). According to the classic theory for the formation of algal blooms "critical depth" and "eutrophication", oligotrophic sea area is usually difficult to form a large area of algal blooms, and actuallythe traditional observation is only sporadic capture to the existence of algal blooms.Taking full advantage of multiple data of satellite remote sensing , this study introduces "Wind-driven algal blooms in open oceans: observation and mechanisms" It explained except classic coastal Ekman transport, the wind through a variety of mechanisms affecting the formation of algal blooms. Proposed a conceptual model of "Strong wind -upwelling-nutrient-phytoplankton blooms" in Western South China Sea (SCS) to assess role of wind-induced advection transport in phytoplankton bloom formation. It illustrates the nutrient resources that support long-term offshore phytoplankton blooms in the western SCS; (2)Proposal of the theory that "typhoons cause vertical mixing, induce phytoplankton blooms", and quantify their important contribution to marine primary production; Proposal a new ecological index for typhoon. Proposed remote sensing inversion models. (3)Finding of the spatial and temporaldistributions pattern of harmful algal bloom (HAB)and species variations of HAB in the South Yellow Sea and East China Sea, and in the Pearl River estuary, and their oceanic dynamic mechanisms related with monsoon; The project developed new techniques and generated new knowledge, which significantly improved understanding of the formation mechanisms of algal blooms. The proposed "wind-pump" mechanism integrates theoretical system combined "ocean dynamics, development of algal blooms, and impact on primary production", which will benefit fisheries management. These

  12. Computations of wind-driven ocean-induced magnetic fields

    Science.gov (United States)

    Sachl, Libor; Einspigel, David; Martinec, Zdenek

    2016-04-01

    We present the results of computations of the secondary magnetic field induced by ocean motions. Ocean velocities are computed using the baroclinic ocean model LSOMG. The velocities are then used to determine the Lorentz force which is plugged into the magnetic induction code TLAM as a principal forcing. The TLAM is a 2D magnetic induction code based on the thin-shell approximation (Vivier et al., 2004; Tyler et al., 1997). In this approximation, the equation of magnetic induction simplifies significantly, time derivatives of main and induced magnetic fields are neglected as well as the self-induction term. The price for simplification of governing equations is the limited applicability of the resulting system. It is only suitable for slowly evolving processes. In order to meet the condition, we restrict ourselves to the wind (buoyancy) driven ocean circulation, although the LSOMG model is able to model both tidally- and wind-driven circulations. We assess the accuracy of thin-shell approximation in our setup by comparing the results with the Swarm satellite magnetic data. References Tyler, R. H., Mysak, L. A., and Oberhuber, J. M, 1997. Electromagnetic fields generated by a three dimensional global ocean circulation. J. Geophys. Res., 102, 5531-5551. Vivier, F., Meier-Reimer, E., and Tyler, R. H., 2004. Simulations of magnetic fields generated by the Antarctic Circumpolar Current at satellite altitude: Can geomagnetic measurements be used to monitor the flow? Geophys. Res. Lett., 31, L10306, doi:10.1029/2004GL019804.

  13. Overall Optimization for Offshore Wind Farm Electrical System

    DEFF Research Database (Denmark)

    Hou, Peng; Hu, Weihao; Chen, Cong

    2017-01-01

    Based on particle swarm optimization (PSO), an optimization platform for offshore wind farm electrical system (OWFES) is proposed in this paper, where the main components of an offshore wind farm and key technical constraints are considered as input parameters. The offshore wind farm electrical...... system is optimized in accordance with initial investment by considering three aspects: the number and siting of offshore substations (OS), the cable connection layout of both collection system (CS) and transmission system (TS) as well as the selection of electrical components in terms of voltage level...

  14. Data driven fault detection and isolation: a wind turbine scenario

    Directory of Open Access Journals (Sweden)

    Rubén Francisco Manrique Piramanrique

    2015-04-01

    Full Text Available One of the greatest drawbacks in wind energy generation is the high maintenance cost associated to mechanical faults. This problem becomes more evident in utility scale wind turbines, where the increased size and nominal capacity comes with additional problems associated with structural vibrations and aeroelastic effects in the blades. Due to the increased operation capability, it is imperative to detect system degradation and faults in an efficient manner, maintaining system integrity, reliability and reducing operation costs. This paper presents a comprehensive comparison of four different Fault Detection and Isolation (FDI filters based on “Data Driven” (DD techniques. In order to enhance FDI performance, a multi-level strategy is used where:  the first level detects the occurrence of any given fault (detection, while  the second identifies the source of the fault (isolation. Four different DD classification techniques (namely Support Vector Machines, Artificial Neural Networks, K Nearest Neighbors and Gaussian Mixture Models were studied and compared for each of the proposed classification levels. The best strategy at each level could be selected to build the final data driven FDI system. The performance of the proposed scheme is evaluated on a benchmark model of a commercial wind turbine. 

  15. The relationship between wind power, electricity demand and winter weather patterns in Great Britain

    Science.gov (United States)

    Thornton, Hazel E.; Scaife, Adam A.; Hoskins, Brian J.; Brayshaw, David J.

    2017-06-01

    Wind power generation in Great Britain has increased markedly in recent years. However due to its intermittency its ability to provide power during periods of high electricity demand has been questioned. Here we characterise the winter relationship between electricity demand and the availability of wind power. Although a wide range of wind power capacity factors is seen for a given demand, the average capacity factor reduces by a third between low and high demand. However, during the highest demand average wind power increases again, due to strengthening easterly winds. The nature of the weather patterns affecting Great Britain are responsible for this relationship. High demand is driven by a range of high pressure weather types, each giving cold conditions, but variable wind power availability. Offshore wind power is sustained at higher levels and offers a more secure supply compared to that onshore. However, during high demand periods in Great Britain neighbouring countries may struggle to provide additional capacity due to concurrent low temperatures and low wind power availability.

  16. Wind power and a liberalised North European electricity exchange

    Energy Technology Data Exchange (ETDEWEB)

    Nielsen, L.H.; Morthorst, P.E.; Skytte, K. [and others

    1999-03-01

    Conditions for wind power on a liberalised North European electrical power market are addressed in the paper. Results are presented from a recently completed study carried out by Risoe National Laboratory in collaboration with the Danish electric utilities Eltra, Elsam and Elkraft. A main result from the study is, that the market will be able to provide the necessary power regulation, that will be required year 2005 as consequence of the expected wind power capacity extension, according to the Danish energy plan, Energy21. The averege sales price on the market for the wind-generated electricity is less than the average spot market price, due to provision of power regulation to balance the unpredictability of the wind power. This reduction in the market value of wind power has been calculated to 10-20 DKK/MWh of 1.3-2.7 EUR/MWh. (au)

  17. The General Electric MOD-1 wind turbine generator program

    Science.gov (United States)

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

    1979-01-01

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

  18. The predictability of large-scale wind-driven flows

    Directory of Open Access Journals (Sweden)

    A. Mahadevan

    2001-01-01

    Full Text Available The singular values associated with optimally growing perturbations to stationary and time-dependent solutions for the general circulation in an ocean basin provide a measure of the rate at which solutions with nearby initial conditions begin to diverge, and hence, a measure of the predictability of the flow. In this paper, the singular vectors and singular values of stationary and evolving examples of wind-driven, double-gyre circulations in different flow regimes are explored. By changing the Reynolds number in simple quasi-geostrophic models of the wind-driven circulation, steady, weakly aperiodic and chaotic states may be examined. The singular vectors of the steady state reveal some of the physical mechanisms responsible for optimally growing perturbations. In time-dependent cases, the dominant singular values show significant variability in time, indicating strong variations in the predictability of the flow. When the underlying flow is weakly aperiodic, the dominant singular values co-vary with integral measures of the large-scale flow, such as the basin-integrated upper ocean kinetic energy and the transport in the western boundary current extension. Furthermore, in a reduced gravity quasi-geostrophic model of a weakly aperiodic, double-gyre flow, the behaviour of the dominant singular values may be used to predict a change in the large-scale flow, a feature not shared by an analogous two-layer model. When the circulation is in a strongly aperiodic state, the dominant singular values no longer vary coherently with integral measures of the flow. Instead, they fluctuate in a very aperiodic fashion on mesoscale time scales. The dominant singular vectors then depend strongly on the arrangement of mesoscale features in the flow and the evolved forms of the associated singular vectors have relatively short spatial scales. These results have several implications. In weakly aperiodic, periodic, and stationary regimes, the mesoscale energy

  19. Centralized electricity generation in offshore wind farms using hydraulic networks

    NARCIS (Netherlands)

    Jarquin Laguna, A.

    2017-01-01

    The work presented in this thesis explores a new way of generation, collection and transmission of wind energy inside a wind farm, in which the electrical conversion does not occur during any intermediate conversion step before the energy has reached the offshore central platform. A centralized

  20. assessment of wind energy potential for electricity generation in ...

    African Journals Online (AJOL)

    Renewable energy sources such as wind, if thoroughly investigated, could be used to reduce the dependence on fossil fuels for electricity generation. Although wind energy is one of the most efficient renewable energy sources, it is very variable compared to other sources of energy. It is also more sensitive to variations with ...

  1. Method and device for current driven electric energy conversion

    DEFF Research Database (Denmark)

    2012-01-01

    Device comprising an electric power converter circuit for converting electric energy. The converter circuit comprises a switch arrangement with two or more controllable electric switches connected in a switching configuration and controlled so as to provide a current drive of electric energy from...... an associated electric source connected to a set of input terminals. This is obtained by the two or more electric swiches being connected and controlled to short-circuit the input terminals during a part of a switching period. Further, a low pass filter with a capacitor and an inductor are provided to low pass...... distance transmission of electric energy. In many applications the total size of filter components (capacitors and inductors) can be reduced compared to voltage driven topologies. One application is an audio amplifier arranged to drive a loudspeaker....

  2. Modelling and Analysis of Radial Flux Surface Mounted Direct-Driven PMSG in Small Scale Wind Turbine

    Directory of Open Access Journals (Sweden)

    Theint Zar Htet

    2017-11-01

    Full Text Available This paper presents the modelling and analysis of permanent magnet synchronous generator (PMSG which are used in direct driven small scale wind turbines. The 3 kW PM generator which is driven directly without gear system is analyzed by Ansoft Maxwell 2D RMxprt. The performance analysis of generator includes the cogging torque in two teeth, induced coil voltages under load, winding current under load, airgap flux density distribution and so on. The modelling analysis is based on the 2D finite element techniques. In an electrical machine, an accurate determination of the geometry parameters is a vital role. The proper performance results of 3kW PMSG in small scale wind turbine can be seen in this paper.

  3. Electric-Field-Driven Direct Desulfurization.

    Science.gov (United States)

    Borca, Bogdana; Michnowicz, Tomasz; Pétuya, Rémi; Pristl, Marcel; Schendel, Verena; Pentegov, Ivan; Kraft, Ulrike; Klauk, Hagen; Wahl, Peter; Gutzler, Rico; Arnau, Andrés; Schlickum, Uta; Kern, Klaus

    2017-05-23

    The ability to elucidate the elementary steps of a chemical reaction at the atomic scale is important for the detailed understanding of the processes involved, which is key to uncover avenues for improved reaction paths. Here, we track the chemical pathway of an irreversible direct desulfurization reaction of tetracenothiophene adsorbed on the Cu(111) closed-packed surface at the submolecular level. Using the precise control of the tip position in a scanning tunneling microscope and the electric field applied across the tunnel junction, the two carbon-sulfur bonds of a thiophene unit are successively cleaved. Comparison of spatially mapped molecular states close to the Fermi level of the metallic substrate acquired at each reaction step with density functional theory calculations reveals the two elementary steps of this reaction mechanism. The first reaction step is activated by an electric field larger than 2 V nm(-1), practically in absence of tunneling electrons, opening the thiophene ring and leading to a transient intermediate. Subsequently, at the same threshold electric field and with simultaneous injection of electrons into the molecule, the exergonic detachment of the sulfur atom is triggered. Thus, a stable molecule with a bifurcated end is obtained, which is covalently bound to the metallic surface. The sulfur atom is expelled from the vicinity of the molecule.

  4. Market integration of wind power in electricity system balancing

    DEFF Research Database (Denmark)

    Sorknæs, Peter; Andersen, Anders N.; Tang, Jens

    2013-01-01

    In most countries markets for electricity are divided into wholesale markets on which electricity is traded before the operation hour, and real-time balancing markets to handle the deviations from the wholesale trading. So far, wind power has been sold only on the wholesale market and has been...... known to increase the need for balancing. This article analyses whether wind turbines in the future should participate in the balancing markets and thereby play a proactive role. The analysis is based on a real-life test of proactive participation of a wind farm in West Denmark. It is found...

  5. Wind power electric systems modeling, simulation and control

    CERN Document Server

    Rekioua, Djamila

    2014-01-01

    The book helps readers understand key concepts in standalone and grid connected wind energy systems and features analysis into the modeling and optimization of commonly used configurations through the implementation of different control strategies.Utilizing several electrical machinery control approaches, such as vector control and direct torque control 'Wind Power Electric Systems' equips readers with the means to understand, assess and develop their own wind energy systems and to evaluate the performance of such systems.Mathematical models are provided for each system and a corresponding MAT

  6. Electric vehicles and large-scale integration of wind power

    DEFF Research Database (Denmark)

    Liu, Wen; Hu, Weihao; Lund, Henrik

    2013-01-01

    integration by 8%. The application of EVs benefits from saving both energy system cost and fuel cost. However, the negative consequences of decreasing energy system efficiency and increasing the CO2 emission should be noted when applying the hydrogen fuel cell vehicle (HFCV). The results also indicate...... was 6.5% in 2009 and which has the plan to develop large-scale wind power. The results show that electric vehicles (EVs) have the ability to balance the electricity demand and supply and to further the wind power integration. In the best case, the energy system with EV can increase wind power...

  7. Nonspherical Radiation Driven Wind Models Applied to Be Stars

    Science.gov (United States)

    Arauxo, F. X.

    1990-11-01

    ABSTRACT. In this work we present a model for the structure of a radiatively driven wind in the meridional plane of a hot star. Rotation effects and simulation of viscous forces were included in the motion equations. The line radiation force is considered with the inclusion of the finite disk correction in self-consistent computations which also contain gravity darkening as well as distortion of the star by rotation. An application to a typical BlV star leads to mass-flux ratios between equator and pole of the order of 10 and mass loss rates in the range 5.l0 to Mo/yr. Our envelope models are flattened towards the equator and the wind terminal velocities in that region are rather high (1000 Km/s). However, in the region near the star the equatorial velocity field is dominated by rotation. RESUMEN. Se presenta un modelo de la estructura de un viento empujado radiativamente en el plano meridional de una estrella caliente. Se incluyeron en las ecuaciones de movimiento los efectos de rotaci6n y la simulaci6n de fuerzas viscosas. Se consider6 la fuerza de las lineas de radiaci6n incluyendo la correcci6n de disco finito en calculos autoconsistentes los cuales incluyen oscurecimiento gravitacional asi como distorsi6n de la estrella por rotaci6n. La aplicaci6n a una estrella tipica BlV lleva a cocientes de flujo de masa entre el ecuador y el polo del orden de 10 de perdida de masa en el intervalo 5.l0 a 10 Mo/ano. Nuestros modelos de envolvente estan achatados hacia el ecuador y las velocidads terminales del viento en esa regi6n son bastante altas (1000 Km/s). Sin embargo, en la regi6n cercana a la estrella el campo de velocidad ecuatorial esta dominado por la rotaci6n. Key words: STARS-BE -- STARS-WINDS

  8. Survey of wind power potential for wind-based electricity

    African Journals Online (AJOL)

    Mgina

    2006-12-31

    Dec 31, 2006 ... for 12 months. INTRODUCTION. Generation of electricity world wide is mainly from fossil fuels, renewable and nuclear sources. Fossil fuel sources currently provide a larger share of world electricity generation than any other energy resource and are expected to remain in that position. f o r. m o r e. t h a n a.

  9. Wind turbines for electric utilities - Development status and economics

    Science.gov (United States)

    Ramler, J. R.; Donovan, R. M.

    1979-01-01

    The technology and economics of the large, horizontal-axis wind turbines currently in the Federal Wind Energy Program are presented. Wind turbine technology advancements made in the last several years are discussed. It is shown that, based on current projections of the costs of these machines when produced in quantity, they should be attractive for utility application. The cost of electricity (COE) produced at the busbar is shown to be a strong function of the mean wind speed at the installation site. The breakeven COE as a 'fuel saver' is discussed and the COE range that would be generally attractive to utilities is indicated.

  10. Wind turbines for electric utilities: Development status and economics

    Science.gov (United States)

    Ramler, J. R.; Donovan, R. M.

    1979-01-01

    The technology and economics of the large, horizontal-axis wind turbines currently in the Federal Wind Energy Program are presented. Wind turbine technology advancements made in the last several years are discussed. It is shown that, based on current projections of the costs of these machines when produced in quantity, they should be attractive for utility application. The cost of electricity (COE) produced at the busbar is shown to be a strong function of the mean wind speed at the installation site. The breakeven COE as a fuel saver is discussed and the COE range that would be generally attractive to utilities is indicated.

  11. Standard test method to determine the performance of tiled roofs to wind-driven rain

    OpenAIRE

    Sánchez de Rojas, M. I.; Marín Andrés, F.

    2008-01-01

    The extent to which roof coverings can resist water penetration from the combination of wind and rain, commonly referred to as wind driven rain, is important for the design of roofs. A new project of European Standard prEN 15601 (1) specifies a method of test to determine the performance of the roof covering against wind driven rain. The combined action of wind and rain varies considerably with geographical location of a building and the associated differences in the rain and wind climate. Th...

  12. Using Rare Earth Elements (REE) to determine wind-driven soil dispersal from a point source

    Science.gov (United States)

    Although erosion of soil by water is a predictably directional process, the erosion of soil by wind is determined by wind direction on an event-wise basis. The wind-driven dispersal patterns of chemical constituents including natural soil components and anthropogenic contaminants are not well under...

  13. Sharing wind power forecasts in electricity markets: A numerical analysis

    DEFF Research Database (Denmark)

    Exizidis, Lazaros; Pinson, Pierre; Kazempour, Jalal

    2016-01-01

    In an electricity pool with significant share of wind power, all generators including conventional and wind power units are generally scheduled in a day-ahead market based on wind power forecasts. Then, a real-time market is cleared given the updated wind power forecast and fixed day......-ahead decisions to adjust power imbalances. This sequential market-clearing process may cope with serious operational challenges such as severe power shortage in real-time due to erroneous wind power forecasts in day-ahead market. To overcome such situations, several solutions can be considered such as adding...... flexible resources to the system. In this paper, we address another potential solution based on information sharing in which market players share their own wind power forecasts with others in day-ahead market. This solution may improve the functioning of sequential market-clearing process through making...

  14. The pursuit of electrically-driven organic semiconductor lasers

    NARCIS (Netherlands)

    Bisri, Satria Zulkarnaen; Takenobu, Taishi; Iwasa, Yoshihiro

    2014-01-01

    Organic semiconductors have many favourable and plastic-like optical properties that are promising for the development of low energy consuming laser devices. Although optically-pumped organic semiconductor lasers have been demonstrated since the early days of lasers, electrically-driven organic

  15. Reliability assessment of bulk electric systems containing large wind farms

    Energy Technology Data Exchange (ETDEWEB)

    Wangdee, Wijarn [Regional System Planning, British Columbia Transmission Corporation, Vancouver (Canada); Billinton, Roy [Power System Research Group, University of Saskatchewan, Saskatoon (Canada)

    2007-12-15

    Wind power is an intermittent energy source that behaves quite differently than conventional energy sources. Bulk electric system reliability analysis associated with wind energy conversion systems (WECS) provides an opportunity to investigate the reliability benefits when large-scale wind power is injected at specified locations in a bulk electric system. Connecting the WECS to different locations in a bulk system can have different impacts on the overall system reliability depending on the system topology and conditions. Connecting a large-scale WECS to an area which has weak transmission could create system operating constraints and provide less system benefit than connecting it to an area with stronger transmission. This paper investigates bulk electric system transmission constraints associated with large-scale wind farms. The analyses presented in this paper can be used to determine the maximum WECS installed capacity that can be injected at specified locations in a bulk electric system, and assist system planners to create potential transmission reinforcement schemes to facilitate large-scale WECS additions to the bulk system. A sequential Monte Carlo simulation approach is used as this methodology can facilitate a time series modeling of wind speeds, and also provides accurate frequency and duration assessments. An auto-regressive moving average (ARMA) time series model is used to simulate hourly wind speeds. (author)

  16. Electrically Driven Ion Separations in Permeable Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Bruening, Merlin [Michigan State Univ., East Lansing, MI (United States)

    2017-04-21

    Membranes are attractive for a wide range of separations due to their low energy costs and continuous operation. To achieve practical fluxes, most membranes consist of a thin, selective skin on a highly permeable substrate that provides mechanical strength. Thus, this project focused on creating new methods for forming highly selective ultrathin skins as well as modeling transport through these coatings to better understand their unprecedented selectivities. The research explored both gas and ion separations, and the latter included transport due to concentration, pressure and electrical potential gradients. This report describes a series of highlights of the research and then provides a complete list of publications supported by the grant. These publications have been cited more than 4000 times. Perhaps the most stunning finding is the recent discovery of monovalent/divalent cation and anion selectivities around 1000 when modifying cation- and anion-exchange membranes with polyelectrolyte multilayers (PEMs). This discovery builds on many years of exciting research. (Citation numbers refer to the journal articles in the bibliography.)

  17. Electric field driven torque in ATP synthase.

    Directory of Open Access Journals (Sweden)

    John H Miller

    Full Text Available FO-ATP synthase (FO is a rotary motor that converts potential energy from ions, usually protons, moving from high- to low-potential sides of a membrane into torque and rotary motion. Here we propose a mechanism whereby electric fields emanating from the proton entry and exit channels act on asymmetric charge distributions in the c-ring, due to protonated and deprotonated sites, and drive it to rotate. The model predicts a scaling between time-averaged torque and proton motive force, which can be hindered by mutations that adversely affect the channels. The torque created by the c-ring of FO drives the γ-subunit to rotate within the ATP-producing complex (F1 overcoming, with the aid of thermal fluctuations, an opposing torque that rises and falls with angular position. Using the analogy with thermal Brownian motion of a particle in a tilted washboard potential, we compute ATP production rates vs. proton motive force. The latter shows a minimum, needed to drive ATP production, which scales inversely with the number of proton binding sites on the c-ring.

  18. Non-Axisymmetric Line Driven Disc Winds I - Disc Perturbations

    Science.gov (United States)

    Dyda, Sergei; Proga, Daniel

    2018-01-01

    We study mass outflows driven from accretion discs by radiation pressure due to spectral lines. To investigate non-axisymmetric effects, we use the ATHENA++ code and develop a new module to account for radiation pressure driving. In 2D, our new simulations are consistent with previous 2D axisymmetric solutions by Proga et al. who used the ZEUS 2D code. Specifically, we find that the disc winds are time dependent, characterized by a dense stream confined to ˜45° relative to the disc midplane and bounded on the polar side by a less dense, fast stream. In 3D we introduce a vertical, ϕ-dependent, subsonic velocity perturbation in the disc midplane. The perturbation does not change the overall character of the solution but global outflow properties such as the mass, momentum and kinetic energy fluxes are altered by up to 100%. Non-axisymmetric density structures develop and persist mainly at the base of the wind. They are relatively small, and their densities can be a few times higher that the azimuthal average. The structure of the non-axisymmetric and axisymmetric solutions differ also in other ways. Perhaps most importantly from the observational point of view are the differences in the so called clumping factors, that serve as a proxy for emissivity due to two body processes. In particular, the spatially averaged clumping factor over the entire fast stream, while it is of a comparable value in both solutions, it varies about 10 times faster in the non-axisymmetric case.

  19. Reversible Electric-Field-Driven Magnetic Domain-Wall Motion

    Directory of Open Access Journals (Sweden)

    Kévin J. A. Franke

    2015-02-01

    Full Text Available Control of magnetic domain-wall motion by electric fields has recently attracted scientific attention because of its potential for magnetic logic and memory devices. Here, we report on a new driving mechanism that allows for magnetic domain-wall motion in an applied electric field without the concurrent use of a magnetic field or spin-polarized electric current. The mechanism is based on elastic coupling between magnetic and ferroelectric domain walls in multiferroic heterostructures. Pure electric-field-driven magnetic domain-wall motion is demonstrated for epitaxial Fe films on BaTiO_{3} with in-plane and out-of-plane polarized domains. In this system, magnetic domain-wall motion is fully reversible and the velocity of the walls varies exponentially as a function of out-of-plane electric-field strength.

  20. Electric Vehicles in Power Systems with 50% Wind Power Penetration

    DEFF Research Database (Denmark)

    Østergaard, Jacob; Foosnæs, Anders; Xu, Zhao

    2009-01-01

    Electric vehicles (EVs) provide a unique opportunity to reduce the CO2-emissions from the transport sector. At the same time, EVs have the potential to play an important role in an economic and reliable operation of an electricity system with high penetration of renewable energy. EVs...... will be an important balancing measure to enable the Danish government’s energy strategy, which implies 50% wind power penetration in the electric power system. An EV will be a storage device for smoothing power fluctuations from renewable resources especially wind power and provide valuable system services...... for a reliable power system operation. Cost-benefit analysis shows that intelligent bidirectional charging – vehicle to grid (V2G) – provides a socio-economic profit of 150 million Euro/year in the Danish electric power system in 2025 assuming that 15% of the Danish road transport need is supplied by electricity...

  1. Towards 50% wind electricity in Denmark: Dilemmas and challenges

    Science.gov (United States)

    Bach, Paul-Frederik

    2016-05-01

    Electricity and heat supply systems are essential contributors to a fossil-free future in Denmark. The combined production of heat and power (CHP) and the production of wind energy are already well developed in Denmark. Combined heat and power covers about 40% of the demand for space heating in Denmark, and the production of wind energy is supposed to exceed 50% of the demand for electricity by 2020. The changing electricity and heat production has some consequences already now: i) Decreasing wholesale prices in Denmark and in other countries. ii) Thermal power plants are closing down. Denmark is no longer self-sufficient with electricity under all conditions. iii) The electricity production pattern does not match the demand pattern. The result is that the neighbouring countries must absorb the variations from wind and solar power. Essential challenges: i) The future of combined heat and power in Denmark is uncertain. ii) Denmark will need new backup capacity for filling the gaps in wind power and solar cell output. iii) Flexible electricity consumers are supposed to contribute to balancing the future power systems. There is still a long way to go before the Smart Grid visions are implemented in large scale. iv) The transformation of the power system will create new risks of power failures.

  2. Star Formation-Driven Winds in the Early Universe

    Science.gov (United States)

    Peek, Matthew; Lundgren, Britt; Brammer, Gabriel

    2018-01-01

    Measuring the extent of star formation-driven winds from galaxies in the early universe is crucial for understanding of how galaxies evolve over cosmic time. Using WFC3/IR grism data from the Hubble Space Telescope (HST), we have measured the star formation rates and star formation rate surface densities of several hundred galaxies at redshift (z) = 1, when the universe was roughly half its present age. The galaxies we examine are also probed by background quasars, whose spectra provide information about the extent of metal-enriched gas in their halos. We use a computational pipeline to measure the density of the star formation in each galaxy and correlate these measurements with detections of Mg II absorption in nearby quasar spectra from the Sloan Digital Sky Survey. Our preliminary results support a model in which galaxies with high SFR surface densities drive metal-enriched gas out of the disk and into these galaxies’ extended halos, where that gas is detected in the spectra of more distant quasars.

  3. Scaling Relations of Starburst-driven Galactic Winds

    Science.gov (United States)

    Tanner, Ryan; Cecil, Gerald; Heitsch, Fabian

    2017-07-01

    Using synthetic absorption lines generated from 3D hydrodynamical simulations, we explore how the velocity of a starburst-driven galactic wind correlates with the star formation rate (SFR) and SFR density. We find strong correlations for neutral and low ionized gas, but no correlation for highly ionized gas. The correlations for neutral and low ionized gas only hold for SFRs below a critical limit set by the mass loading of the starburst, above which point the scaling relations flatten abruptly. Below this point the scaling relations depend on the temperature regime being probed by the absorption line, not on the mass loading. The exact scaling relation depends on whether the maximum or mean velocity of the absorption line is used. We find that the outflow velocity of neutral gas can be up to five times lower than the average velocity of ionized gas, with the velocity difference increasing for higher ionization states. Furthermore, the velocity difference depends on both the SFR and mass loading of the starburst. Thus, absorption lines of neutral or low ionized gas cannot easily be used as a proxy for the outflow velocity of the hot gas.

  4. Forecasting wind-driven wildfires using an inverse modelling approach

    Directory of Open Access Journals (Sweden)

    O. Rios

    2014-06-01

    Full Text Available A technology able to rapidly forecast wildfire dynamics would lead to a paradigm shift in the response to emergencies, providing the Fire Service with essential information about the ongoing fire. This paper presents and explores a novel methodology to forecast wildfire dynamics in wind-driven conditions, using real-time data assimilation and inverse modelling. The forecasting algorithm combines Rothermel's rate of spread theory with a perimeter expansion model based on Huygens principle and solves the optimisation problem with a tangent linear approach and forward automatic differentiation. Its potential is investigated using synthetic data and evaluated in different wildfire scenarios. The results show the capacity of the method to quickly predict the location of the fire front with a positive lead time (ahead of the event in the order of 10 min for a spatial scale of 100 m. The greatest strengths of our method are lightness, speed and flexibility. We specifically tailor the forecast to be efficient and computationally cheap so it can be used in mobile systems for field deployment and operativeness. Thus, we put emphasis on producing a positive lead time and the means to maximise it.

  5. Electrical and non-electrical environment of wind turbine main components

    DEFF Research Database (Denmark)

    Holboell, J.; Henriksen, M.; Olsen, R.S.

    Focus on the development of offshore wind power, and expectations to turbines and substations to operate reliably under all conditions, causes interest in determining exactly what is unique about the wind turbine environment. If not properly dealt with, this environment can shorten the lifetime...... of the electrical components or even lead to catastrophic component failure. In the present paper, results are presented from investigations on existing standards which give detailed descriptions of the environmental and operational conditions of wind turbine components. It is found that there is currently a lack...... of application standards for wind turbine electrical equipment. Component-level environmental requirements as given in equipment-specific standards are compared with the environment described in the IEC's 61400 series concerning wind turbines. Based on methods defined in IEC 60721, the non-electrical environment...

  6. Wind energy in a competitive electricity supply environment

    Energy Technology Data Exchange (ETDEWEB)

    Strbac, G.; Jenkins, N. [Manchester Centre for Electrical Energy, Manchester (United Kingdom)

    1995-12-31

    In the UK, there has been an increasing interest in the commercial aspects of the impact of wind energy on transmission and distribution networks. In a competitive electricity supply environment, mechanisms for pricing network services are considered to be the main vehicle for evaluating that impact. This article reviews the major pricing strategies based on embedded costs, short and long run marginal costing theory as well as time-of-use pricing, and comments on the influence of each particular strategy on the calculated value of wind energy. Also, prospective tools for evaluating savings in capital and operating network costs due to wind generation, are identified. (author)

  7. Dynamics of Line-Driven Winds from Disks in Cataclysmic Variables. I. Solution Topology and Wind Geometry

    OpenAIRE

    Feldmeier, Achim; Shlosman, Isaac

    1999-01-01

    We analyze the dynamics of 2-D stationary, line-driven winds from accretion disks in cataclysmic variable stars. The driving force is that of line radiation pressure, in the formalism developed by Castor, Abbott & Klein for O stars. Our main assumption is that wind helical streamlines lie on straight cones. We find that the Euler equation for the disk wind has two eigenvalues, the mass loss rate and the flow tilt angle with the disk. Both are calculated self-consistently. The wind is characte...

  8. Optimal contracts for wind power producers in electricity markets

    KAUST Repository

    Bitar, E.

    2010-12-01

    This paper is focused on optimal contracts for an independent wind power producer in conventional electricity markets. Starting with a simple model of the uncertainty in the production of power from a wind turbine farm and a model for the electric energy market, we derive analytical expressions for optimal contract size and corresponding expected optimal profit. We also address problems involving overproduction penalties, cost of reserves, and utility of additional sensor information. We obtain analytical expressions for marginal profits from investing in local generation and energy storage. ©2010 IEEE.

  9. Meeting residential space heating demand with wind-generated electricity

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, Larry [Electrical and Computer Engineering, Energy Research Group, Dalhousie University, Halifax, Nova Scotia (Canada)

    2010-08-15

    Worldwide, many electricity suppliers are faced with the challenge of trying to integrate intermittent renewables, notably wind, into their energy mix to meet the needs of those services that require a continuous supply of electricity. Solutions to intermittency include the use of rapid-response backup generation and chemical or mechanical storage of electricity. Meanwhile, in many jurisdictions with lengthy heating seasons, finding secure and preferably environmentally benign supplies of energy for space heating is also becoming a significant challenge because of volatile energy markets. Most, if not all, electricity suppliers treat these twin challenges as separate issues: supply (integrating intermittent renewables) and demand (electric space heating). However, if space heating demand can be met from an intermittent supply of electricity, then both of these issues can be addressed simultaneously. One such approach is to use off-the-shelf electric thermal storage systems. This paper examines the potential of this approach by applying the output from a 5.15 MW wind farm to the residential heating demands of detached households in the Canadian province of Prince Edward Island. The paper shows that for the heating season considered, up to 500 households could have over 95 percent of their space heating demand met from the wind farm in question. The benefits as well as the limitations of the approach are discussed in detail. (author)

  10. Understanding the relation between wind- and pressure-driven sea level variability

    Science.gov (United States)

    Ponte, Rui M.

    1994-01-01

    Sea surface adjustment to combined wind and pressure forcing is examined using numerical solutions to the shallow water equations. The experiments use coastal geometry and bottom topography representative of the North Atlantic and are forced by realistic barometric pressure and wind stress fields. The repsonse to pressure is essentially static or close to the inverted barometer solution at periods longer than a few days and dominates the sea level variability, with wind-driven sea level signals being relatively small. With regard to the dynamic signals, wind-driven fluctuations dominate at long periods, as expected from quasi-geostrophic theory. Pressure becomes more important than wind stress as a source of dynamic signals only at periods shorter than approximately three days. Wind- and pressure-driven sea level fluctuations are anticorrelated over most regions. Hence, regressions of sea level on barometric pressure yield coefficients generally smaller than expected for the inverted barometer response known to be the case in the model. In the regions of significant wind-pressure correlation effects, to infer the correct pressure reponse using statistical methods, input fields must include winds as well as pressure. Because of the nonlocal character of the wind response, multivariate statistical models with local wind driving as input are not very successful. Inclusion of nonlocal wind variability over extensive regions is necessary to extract the correct pressure response. Implications of these results to the interpretation of sea level observations are discussed.

  11. A 225 kW Direct Driven PM Generator Adapted to a Vertical Axis Wind Turbine

    Directory of Open Access Journals (Sweden)

    S. Eriksson

    2011-01-01

    Full Text Available A unique direct driven permanent magnet synchronous generator has been designed and constructed. Results from simulations as well as from the first experimental tests are presented. The generator has been specifically designed to be directly driven by a vertical axis wind turbine and has an unusually low reactance. Generators for wind turbines with full variable speed should maintain a high efficiency for the whole operational regime. Furthermore, for this application, requirements are placed on high generator torque capability for the whole operational regime. These issues are elaborated in the paper and studied through simulations. It is shown that the generator fulfils the expectations. An electrical control can effectively substitute a mechanical pitch control. Furthermore, results from measurements of magnetic flux density in the airgap and no load voltage coincide with simulations. The electromagnetic simulations of the generator are performed by using an electromagnetic model solved in a finite element environment.

  12. Wind and Wave Driven Nearshore Circulation at Cape Hatteras Point

    Science.gov (United States)

    Kumar, N.; Voulgaris, G.; Warner, J. C.; List, J. H.

    2012-12-01

    We have used a measurement and modeling approach to identify hydrodynamic processes responsible for alongshore transport of sediment that can support the maintenance of Diamond Shoals, NC, a large inner-shelf sedimentary convergent feature. As a part of Carolina Coastal Change Processes project, a one month field experiment was conducted around Cape Hatteras point during February, 2010. The instrumentation consisted of 15 acoustic current meters (measuring pressure and velocity profile) deployed in water depths varying from 3-10m and a very high frequency (VHF) beam forming radar system providing surface waves and currents with a resolution of 150 m and a spatial coverage of 10-15 km2. Analysis of field observation suggests that wind-driven circulation and littoral current dominate surf zone and inner shelf processes at least at an order higher than tidally rectified flows. However, the data analysis identified that relevant processes like non-linear advective acceleration, pressure gradient and vortex-force (due to interaction between wave-induced drift and mean flow vorticity), may be significant, but were not assessed accurately due to instrument location and accuracy. To obtain a deeper physical understanding of the hydrodynamics in this study-site, we applied a three-dimensional Coupled-Ocean-Atmosphere-Wave_Sediment-Transport (COAWST) numerical model. The COAWST modeling system is comprised of nested, coupled, three-dimensional ocean-circulation model (ROMS) and wave propagation model (SWAN), configured for the study site to simulate wave height, direction, period and mean current velocities (both Eulerian and Lagrangian). The nesting follows a two-way grid refinement process for the circulation module, and one-way for the wave model. The coarsest parent grid resolved processes on the spatial and temporal scales of mid-shelf to inner-shelf, and subsequent child grids evolved at inner-shelf and surf zone scales. Preliminary results show that the model

  13. Integration of electric drive vehicles in the Danish electricity network with high wind power penetration

    DEFF Research Database (Denmark)

    Chandrashekhara, Divya K; Østergaard, Jacob; Larsen, Esben

    2010-01-01

    /conventional) which are likely to fuel these cars. The study was carried out considering the Danish electricity network state around 2025, when the EDV penetration levels would be significant enough to have an impact on the power system. Some of the interesting findings of this study are - EDV have the potential......This paper presents the results of a study carried out to examine the feasibility of integrating electric drive vehicles (EDV) in the Danish electricity network which is characterised by high wind power penetration. One of the main aims of this study was to examine the effect of electric drive...... vehicles on the Danish electricity network, wind power penetration and electricity market. In particular the study examined the effect of electric drive vehicles on the generation capacity constraints, load curve, cross border transmission capacity and the type of generating sources (renewable...

  14. Global changes in total and wind electricity (1990–2014

    Directory of Open Access Journals (Sweden)

    María del P. Pablo-Romero

    2017-03-01

    Full Text Available Wind energy is one of the renewable energies which have less adverse environmental impact and is becoming economically affordable long before several other renewable energies. Over recent years, substantial additions have been noted in wind energy capacity, although many differences can be observed between countries. Using the latest available data, this paper provides a concise analysis of wind energy and electricity consumption trends for the period 1990–2014 in a dual perspective, by principal world regions and by per capita gross national income levels in 2014. Electricity consumption has been divided into three types of energy: non-renewable, renewable excluding wind and wind energy. Annual rates of change, energy intensity, energy in per capita terms and some ratios have been analyzed. Notable regional differences and trends are observed in the studied variables. The first 15 European Union countries, other developed countries (ODC and East Asian (EAS and South Asian countries (SAS are the regions which currently have the highest wind capacity.

  15. Wind power impacts and electricity storage - a time scale perspective

    DEFF Research Database (Denmark)

    Hedegaard, Karsten; Meibom, Peter

    2012-01-01

    technologies – batteries, flow batteries, compressed air energy storage, electrolysis combined with fuel cells, and electric vehicles – are moreover categorised with respect to the time scales at which they are suited to support wind power integration. While all of these technologies are assessed suitable...

  16. Galactic Winds Driven by Supernovae and Radiation Pressure: Theory and Simulations

    Science.gov (United States)

    Zhang, Dong; Davis, Shane

    2018-01-01

    Galactic winds are ubiquitous in most rapidly star-forming galaxies. They are crucial to the process of galaxy formation and evolution, regulating star formation, shaping the stellar mass function and the mass-metallicity relation, and enriching the intergalactic medium with metals. Although important, the physics of galactic winds is still unclear. Winds may be driven by many mechanisms including overlapping supernovae explosions, radiation pressure of starlight on dust grains, and cosmic rays. However, the growing observations of multiphase structure in galactic winds in a large number of galaxies have not been well explained by any models. In this talk I will focus on the models of supernova- and radiation-pressure-driven winds. Using the state-of-the-art numerical simulations, I will assess the relative merits of these driving mechanisms for accelerating cold and warm clouds to observed velocities, and momentum flux boost during wind propagation.

  17. Optimal Bidding Strategies for Wind Power Producers in the Day-ahead Electricity Market

    Directory of Open Access Journals (Sweden)

    Xiaolin Liu

    2012-11-01

    Full Text Available Wind Power Producers (WPPs seek to maximize profit and minimize the imbalance costs when bidding into the day-ahead market, but uncertainties in the hourly available wind and forecasting errors make the bidding risky. This paper assumes that hourly wind power output given by the forecast follows a normal distribution, and proposes three different bidding strategies, i.e., the expected profit-maximization strategy (EPS, the chance-constrained programming-based strategy (CPS and the multi-objective bidding strategy (ECPS. Analytical solutions under the three strategies are obtained. Comparisons among the three strategies are conducted on a hypothetical wind farm which follows the Spanish market rules. Results show that bid under the EPS is highly dependent on market clearing price, imbalance prices, and also the mean value and standard deviation of wind forecast, and that bid under the CPS is largely driven by risk parameters and the mean value and standard deviation of the wind forecast. The ECPS combining both EPS and CPS tends to choose a compromise bid. Furthermore, the ECPS can effectively control the tradeoff between expected profit and target profit for WPPs operating in volatile electricity markets.

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

    Science.gov (United States)

    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

  19. Numerical model for wind-driven circulation in the Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Bahulayan, N.; Varadachari, V.V.R.

    Wind-driven circulation in the Bay of Bengal, generated by a southwest wind of constant speed (10 m.sec -1) and direction (225 degrees TN), is presented. A non-linear hydrodynamic model is used for the simulation of circulation. Numerical...

  20. Offshore wind farms energy injection in the electrical grid - Lithium battery to mitigate power fluctuations

    OpenAIRE

    IKNI, DJAMEL; Camara, Mamadou Baïlo; Dakyo, Brayima

    2016-01-01

    The wind farm energy injection in the electrical grid generates the economic and technical challenges which must to be solved for successful large scale wind energy integration in electrical grids. Due to wind speed variations, the wind farm output power presents the fluctuating components which are not compatible to the electrical grid requirements. Today, this problem is a major challenge with the wind farm projects increasing in the world. Large power variations cause the deviations of rms...

  1. Systems and methods for an integrated electrical sub-system powered by wind energy

    Science.gov (United States)

    Liu, Yan [Ballston Lake, NY; Garces, Luis Jose [Niskayuna, NY

    2008-06-24

    Various embodiments relate to systems and methods related to an integrated electrically-powered sub-system and wind power system including a wind power source, an electrically-powered sub-system coupled to and at least partially powered by the wind power source, the electrically-powered sub-system being coupled to the wind power source through power converters, and a supervisory controller coupled to the wind power source and the electrically-powered sub-system to monitor and manage the integrated electrically-powered sub-system and wind power system.

  2. The Electrostatic Wind Energy Converter : Electrical performance of a high voltage prototype

    NARCIS (Netherlands)

    Djairam, D.

    2008-01-01

    Wind energy is converted to electrical energy by letting the wind move charged particles against the direction of an electric field. The advantage of this type of conversion is that no rotational movement, which occurs in conventional wind turbines, is required. An electrostatic wind energy

  3. EMSP Final Report: Electrically Driven Technologies for Radioactive Aerosol Abatement

    Energy Technology Data Exchange (ETDEWEB)

    DePaoli, D.W.

    2003-01-22

    The purpose of this research project was to develop an improved understanding of how electrically driven processes, including electrocoalescence, acoustic agglomeration, and electric filtration, may be employed to efficiently treat problems caused by the formation of aerosols during DOE waste treatment operations. The production of aerosols during treatment and retrieval operations in radioactive waste tanks and during thermal treatment operations such as calcination presents a significant problem of cost, worker exposure, potential for release, and increased waste volume. There was anecdotal evidence in the literature that acoustic agglomeration and electrical coalescence could be used together to change the size distribution of aerosol particles in such a way as to promote easier filtration and less frequent maintenance of filtration systems. As such, those electrically driven technologies could potentially be used as remote technologies for improved treatment; however, existing theoretical models are not suitable for prediction and design. To investigate the physics of such systems, and also to prototype a system for such processes, a collaborative project was undertaken between Oak Ridge National Laboratory (ORNL) and the University of Texas at Austin (UT). ORNL was responsible for the larger-scale prototyping portion of the project, while UT was primarily responsible for the detailed physics in smaller scale unit reactors. It was found that both electrical coalescence and acoustic agglomeration do in fact increase the rate of aggregation of aerosols. Electrical coalescence requires significantly less input power than acoustic agglomeration, but it is much less effective in its ability to aggregate/coalesce aerosols. The larger-scale prototype showed qualitatively similar results as the unit reactor tests, but presented more difficulty in interpretation of the results because of the complex multi-physics coupling that necessarily occur in all larger

  4. Evolution of One-Dimensional Wind-Driven Sea Spectra

    OpenAIRE

    Dyachenko, A. I.; Kachulin, D. I.; Zakharov, V. E.

    2016-01-01

    We analyze modern operational models of wind wave prediction on the subject for compliance dissipation. Our numerical simulations from the "first principle" demonstrate that heuristic formulas for damping rate of free wind sea due to "white capping" (or wave breaking) dramatically exaggerates the role of this effect in these models.

  5. Thermal energy storage for electricity-driven space heating in a day-ahead electricity market

    DEFF Research Database (Denmark)

    Pensini, Alessandro

    2012-01-01

    Thermal Energy Storage (TES) in a space heating (SH) application was investigated. The study aimed to determine the economic benefits of introducing TES into an electricity-driven SH system under a day-ahead electricity market. The performance of the TES was assessed by comparing the cost...... of electricity in a system with a TES unit to the case where no storage is in use and the entire heat requirement is fulfilled by purchasing electricity according to the actual load. The study had two goals: 1. Determining how the size – in terms of electricity input (Pmax) and energy capacity (Emax......) – of the TES unit influences the savings. For this purpose, a reference price signal was used. Results show that it is possible to save up to approximately 14% of the electricity costs. In general, savings increase with Pmax and Emax. However, the benefit of increasing these two values ceases when certain...

  6. Optimal Wind Power Uncertainty Intervals for Electricity Market Operation

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ying; Zhou, Zhi; Botterud, Audun; Zhang, Kaifeng

    2018-01-01

    It is important to select an appropriate uncertainty level of the wind power forecast for power system scheduling and electricity market operation. Traditional methods hedge against a predefined level of wind power uncertainty, such as a specific confidence interval or uncertainty set, which leaves the questions of how to best select the appropriate uncertainty levels. To bridge this gap, this paper proposes a model to optimize the forecast uncertainty intervals of wind power for power system scheduling problems, with the aim of achieving the best trade-off between economics and reliability. Then we reformulate and linearize the models into a mixed integer linear programming (MILP) without strong assumptions on the shape of the probability distribution. In order to invest the impacts on cost, reliability, and prices in a electricity market, we apply the proposed model on a twosettlement electricity market based on a six-bus test system and on a power system representing the U.S. state of Illinois. The results show that the proposed method can not only help to balance the economics and reliability of the power system scheduling, but also help to stabilize the energy prices in electricity market operation.

  7. Electric power from offshore wind via synoptic-scale interconnection.

    Science.gov (United States)

    Kempton, Willett; Pimenta, Felipe M; Veron, Dana E; Colle, Brian A

    2010-04-20

    World wind power resources are abundant, but their utilization could be limited because wind fluctuates rather than providing steady power. We hypothesize that wind power output could be stabilized if wind generators were located in a meteorologically designed configuration and electrically connected. Based on 5 yr of wind data from 11 meteorological stations, distributed over a 2,500 km extent along the U.S. East Coast, power output for each hour at each site is calculated. Each individual wind power generation site exhibits the expected power ups and downs. But when we simulate a power line connecting them, called here the Atlantic Transmission Grid, the output from the entire set of generators rarely reaches either low or full power, and power changes slowly. Notably, during the 5-yr study period, the amount of power shifted up and down but never stopped. This finding is explained by examining in detail the high and low output periods, using reanalysis data to show the weather phenomena responsible for steady production and for the occasional periods of low power. We conclude with suggested institutions appropriate to create and manage the power system analyzed here.

  8. Transmission cost minimization strategies for wind-electric generating facilities

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, R. [Northern States Power Company, Minneapolis, MN (United States)

    1997-12-31

    Integrating wind-electric generation facilities into existing power systems presents opportunities not encountered in conventional energy projects. Minimizing outlet cost requires probabilistic value-based analyses appropriately reflecting the wind facility`s operational characteristics. The wind resource`s intermittent nature permits relaxation of deterministic criteria addressing outlet configuration and capacity required relative to facility rating. Equivalent capacity ratings of wind generation facilities being a fraction of installed nameplate rating, outlet design studies contingency analyses can concentrate on this fractional value. Further, given its non-dispatchable, low capacity factor nature, a lower level of redundancy in outlet facilities is appropriate considering the trifling contribution to output unreliability. Further cost reduction opportunities arise from {open_quotes}wind speed/generator power output{close_quotes} and {open_quotes}wind speed/overhead conductor rating{close_quotes} functions` correlation. Proper analysis permits the correlation`s exploitation to safely increase line ratings. Lastly, poor correlation between output and utility load may permit use of smaller conductors, whose higher (mostly off-peak) losses are economically justifiable.

  9. Electric power from offshore wind via synoptic-scale interconnection

    Science.gov (United States)

    Kempton, Willett; Pimenta, Felipe M.; Veron, Dana E.; Colle, Brian A.

    2010-01-01

    World wind power resources are abundant, but their utilization could be limited because wind fluctuates rather than providing steady power. We hypothesize that wind power output could be stabilized if wind generators were located in a meteorologically designed configuration and electrically connected. Based on 5 yr of wind data from 11 meteorological stations, distributed over a 2,500 km extent along the U.S. East Coast, power output for each hour at each site is calculated. Each individual wind power generation site exhibits the expected power ups and downs. But when we simulate a power line connecting them, called here the Atlantic Transmission Grid, the output from the entire set of generators rarely reaches either low or full power, and power changes slowly. Notably, during the 5-yr study period, the amount of power shifted up and down but never stopped. This finding is explained by examining in detail the high and low output periods, using reanalysis data to show the weather phenomena responsible for steady production and for the occasional periods of low power. We conclude with suggested institutions appropriate to create and manage the power system analyzed here. PMID:20368464

  10. Electricity for road transport, flexible power systems and wind power

    Energy Technology Data Exchange (ETDEWEB)

    Nielsen, Lars Henrik; Ravn, H.; Meibom, P. (and others)

    2011-12-15

    The aim of the project is to analyse the potential synergistic interplay that may arise between the power sector and the transport sector, if parts of the road transport energy needs are based on electricity via the utilisation of plug-in hybrid electric vehicles and pure electric vehicles. The project focuses on the technical elements in the chain that comprises: 1: The electric vehicle status, potentials and expected development. Electric batteries are in focus in this part of the analysis. 2: Analysis of plug-in hybrid electric vehicle interacting with a local grid. 3: Analysis of grid-vehicle connection systems including technical regulation options and analysis of needs for standardisation. 4: Setting up scenarios covering potential developments for utilizing electric drive trains in road transport. Period: Up to year 2030. 5: Analysis of capacity constraints in the electricity grid (transmission and distribution) as consequence of increasing electricity demand, and new flexible consumption patterns from segments in the transport sector, and as consequence of increasing capacity on wind power in the system. 6: Setting up and analysis of combined scenarios covering both the heat and power system and the transport sector. (Author)

  11. New algorithm for islanding detection of wind turbines driven DFIG

    Energy Technology Data Exchange (ETDEWEB)

    Mirzaei, Jaber [Monenco Consulting Engineering Company, Tehran (Iran, Islamic Republic of). Dept. of Wind Energy; Kargar, H. Kazemi [Shahid Beheshti Univ., Tehran (Iran, Islamic Republic of). Dept. of Electrical and Computer Engineering

    2011-07-01

    This paper proposes a new algorithm for islanding condition of working in various wind farm loading conditions which is a combination of both passive and active methods for islanding detection of wind farm. The passive part detects probability of islanding conditions and the active part examines and verifies this probable conditions. The buses voltage, first and second order frequency derivation are the parameters which are used in passive part of algorithm and capacitance variations of capacitor banks are employed in active part. This new method was validated by simulation results of Manjil wind farm located in Manjil, Iran. (orig.)

  12. Electrical and Wind Energy Coordination System for Vehicles

    Science.gov (United States)

    Kumar, Rajeev

    2010-11-01

    Nowadays, policies are being developed in many countries in order to decrease their greenhouse gases emissions. While in this area some technologies are widely installed (hydro and solar energy), other ones, like the Wind energy could get an important role in the medium and long term. Coal, gas, diesel, atomic etc. are the basic Natural source of energy. The uses of these sources are also harmful to the nature because they produce the different types of pollution. On the other hand hydro and wind energy are Clean, Green, renewable energy and pollution free sources. Now a day's most of the Company manufactures the hybrid vehicles with the coordination. But they are suffering lot of limitation like the speed of the vehicle and travel distance by the vehicle. So here we have proposed the Electrical and wind energy coordination (EWEC) system. This system is highly useful to improve the overall performance of hybrid vehicle. This system is also 100% pollution free.

  13. Data driven fault detection and isolation: a wind turbine scenario

    National Research Council Canada - National Science Library

    Rubén Francisco Manrique Piramanrique; Jorge Sofrony Esmeral

    2015-01-01

    .... This problem becomes more evident in utility scale wind turbines, where the increased size and nominal capacity comes with additional problems associated with structural vibrations and aeroelastic effects in the blades...

  14. Study on electricity transmission systems for offshore wind power

    OpenAIRE

    Lleonart Pizà, Aina

    2011-01-01

    This project presents the main features of each of the electricity transmission technologies available for offshore wind power and discusses their advantages and disadvantages in terms of technical, economic and environmental aspects. The transmission options studied are High Voltage Alternating Current (HVAC) and High Voltage Direct Current (HVDC). Within the HVDC there are two transmission technologies available, the classical Line Commutated Converter based HVDC and the most re...

  15. Mathematical model “The electric line - wind farm”

    Directory of Open Access Journals (Sweden)

    Merenco V.

    2008-12-01

    Full Text Available It is considered the problem of finding of the mathematical model of a circuit “electric line – wind farm” with the purpose of analysis of operating modes by a method of mathematical simulation. The mathematical model is based on a method of characteristics, takes into account heterogeneity of a circuit and allows realizing various modes and changes in structure of a circuit simple change of values of sizes set as the concentrated parameters.

  16. Impact of Public Aggregate Wind Forecasts on Electricity Market Outcomes

    DEFF Research Database (Denmark)

    Exizidis, Lazaros; Kazempour, Jalal; Pinson, Pierre

    2017-01-01

    Following a call to foster a transparent and more competitive market, member states of the European transmission system operator are required to publish, among other information, aggregate wind power forecasts. The publication of the latter information is expected to benefit market participants b...... that favor social welfare, while over-forecasts will cause the opposite effect. Furthermore, energy and reserve market prices can also be affected by deviations in aggregate wind forecasts altering, inevitably, the profits of all power producers.......Following a call to foster a transparent and more competitive market, member states of the European transmission system operator are required to publish, among other information, aggregate wind power forecasts. The publication of the latter information is expected to benefit market participants...... by offering better knowledge of the market operation, leading subsequently to a more competitive energy market. Driven by the above regulation, we consider an equilibrium study to address how public information of aggregate wind power forecasts can potentially affect market results, social welfare as well...

  17. Wind power electricity: the bigger the turbine, the greener the electricity?

    Science.gov (United States)

    Caduff, Marloes; Huijbregts, Mark A J; Althaus, Hans-Joerg; Koehler, Annette; Hellweg, Stefanie

    2012-05-01

    Wind energy is a fast-growing and promising renewable energy source. The investment costs of wind turbines have decreased over the years, making wind energy economically competitive to conventionally produced electricity. Size scaling in the form of a power law, experience curves and progress rates are used to estimate the cost development of ever-larger turbines. In life cycle assessment, scaling and progress rates are seldom applied to estimate the environmental impacts of wind energy. This study quantifies whether the trend toward larger turbines affects the environmental profile of the generated electricity. Previously published life cycle inventories were combined with an engineering-based scaling approach as well as European wind power statistics. The results showed that the larger the turbine is, the greener the electricity becomes. This effect was caused by pure size effects of the turbine (micro level) as well as learning and experience with the technology over time (macro level). The environmental progress rate was 86%, indicating that for every cumulative production doubling, the global warming potential per kWh was reduced by 14%. The parameters, hub height and rotor diameter were identified as Environmental Key Performance Indicators that can be used to estimate the environmental impacts for a generic turbine. © 2012 American Chemical Society

  18. Effects of El Niño-driven changes in wind patterns on North Pacific albatrosses

    Science.gov (United States)

    Thorne, L. H.; Conners, M. G.; Hazen, E. L.; Bograd, S. J.; Antolos, M.; Costa, D. P.; Shaffer, S. A.

    2016-01-01

    Changes to patterns of wind and ocean currents are tightly linked to climate change and have important implications for cost of travel and energy budgets in marine vertebrates. We evaluated how El Niño-Southern Oscillation (ENSO)-driven wind patterns affected breeding Laysan and black-footed albatross across a decade of study. Owing to latitudinal variation in wind patterns, wind speed differed between habitat used during incubation and brooding; during La Niña conditions, wind speeds were lower in incubating Laysan (though not black-footed) albatross habitat, but higher in habitats used by brooding albatrosses. Incubating Laysan albatrosses benefited from increased wind speeds during El Niño conditions, showing increased travel speeds and mass gained during foraging trips. However, brooding albatrosses did not benefit from stronger winds during La Niña conditions, instead experiencing stronger cumulative headwinds and a smaller proportion of trips in tailwinds. Increased travel costs during brooding may contribute to the lower reproductive success observed in La Niña conditions. Furthermore, benefits of stronger winds in incubating habitat may explain the higher reproductive success of Laysan albatross during El Niño conditions. Our findings highlight the importance of considering habitat accessibility and cost of travel when evaluating the impacts of climate-driven habitat change on marine predators. PMID:27278360

  19. Wind driven mobile charging of automobile battery- A case study

    African Journals Online (AJOL)

    user

    Also, while travelling if the battery gets discharged, then it can create a huge problem ... The PM generator and the circuit can be placed at the position pointed by the ..... Daniel S. A.and Gaunden,N.A. 2001, A stand alone integrated array wind ...

  20. Wind-driven entrainment in a stably stratified fluid

    NARCIS (Netherlands)

    Kranenburg, C.

    1983-01-01

    Experiments on mixed-layer deepening in a straight wind flume initially containing a two-layer fluid were carried out. In order to simulate an effectively unlimited water body, or a situation where the presence of end walls is not yet noticeable, the water from the upper layer was withdrawn at the

  1. Data Driven Modelling of the Dynamic Wake Between Two Wind Turbines

    DEFF Research Database (Denmark)

    Knudsen, Torben; Bak, Thomas

    2012-01-01

    turbine. This paper establishes flow models relating the wind speeds at turbines in a farm. So far, research in this area has been mainly based on first principles static models and the data driven modelling done has not included the loading of the upwind turbine and its impact on the wind speed downwind....... This paper is the first where modern commercial mega watt turbines are used for data driven modelling including the upwind turbine loading by changing power reference. Obtaining the necessary data is difficult and data is therefore limited. A simple dynamic extension to the Jensen wake model is tested...... without much success. The best model turns out to be non linear with upwind turbine loading and wind speed as inputs. Using a transformation of these inputs it is possible to obtain a linear model and use well proven system identification methods. Finally it is shown that including the upwind wind...

  2. Stochastic Optimal Wind Power Bidding Strategy in Short-Term Electricity Market

    DEFF Research Database (Denmark)

    Hu, Weihao; Chen, Zhe; Bak-Jensen, Birgitte

    2012-01-01

    market in order to deal with the uncertainty of the regulation price, the activated regulation of the power system and the forecasted wind power generation. The Danish short-term electricity market and a wind farm in western Denmark are chosen as study cases due to the high wind power penetration here......Due to the fluctuating nature and non-perfect forecast of the wind power, the wind power owners are penalized for the imbalance costs of the regulation, when they trade wind power in the short-term liberalized electricity market. Therefore, in this paper a formulation of an imbalance cost...... minimization problem for trading wind power in the short-term electricity market is described, to help the wind power owners optimize their bidding strategy. Stochastic optimization and a Monte Carlo method are adopted to find the optimal bidding strategy for trading wind power in the short-term electricity...

  3. The system of wind-driven seasonal coastal currents around the Indian subcontinent

    Digital Repository Service at National Institute of Oceanography (India)

    Shetye, S.R.

    stream_size 6698 stream_content_type text/plain stream_name Refresher_Course_Mar_Geol_Geophys_2007_Lecture_Notes_1.pdf.txt stream_source_info Refresher_Course_Mar_Geol_Geophys_2007_Lecture_Notes_1.pdf.txt Content-Encoding UTF-8... in to establish a cause-effect relationship between the winds over the basin and the wind-driven currents along the coast. ...

  4. Modelling renewable electric resources: A case study of wind

    Energy Technology Data Exchange (ETDEWEB)

    Bernow, S.; Biewald, B.; Hall, J.; Singh, D. [Tellus Institute, Boston, MA (United States)

    1994-07-01

    The central issue facing renewables in the integrated resource planning process is the appropriate assessment of the value of renewables to utility systems. This includes their impact on both energy and capacity costs (avoided costs), and on emissions and environmental impacts, taking account of the reliability, system characteristics, interactions (in dispatch), seasonality, and other characteristics and costs of the technologies. These are system-specific considerations whose relationships may have some generic implications. In this report, we focus on the reliability contribution of wind electric generating systems, measured as the amount of fossil capacity they can displace while meeting the system reliability criterion. We examine this issue for a case study system at different wind characteristics and penetration, for different years, with different system characteristics, and with different modelling techniques. In an accompanying analysis we also examine the economics of wind electric generation, as well as its emissions and social costs, for the case study system. This report was undertaken for the {open_quotes}Innovative IRP{close_quotes} program of the U.S. Department of Energy, and is based on work by both Union of Concerned Scientists (UCS) and Tellus Institute, including America`s Energy Choices and the UCS Midwest Renewables Project.

  5. Simulation of an offshore wind farm using fluid power for centralized electricity generation

    NARCIS (Netherlands)

    Jarquin Laguna, A.

    2016-01-01

    A centralized approach for electricity generation within a wind farm is explored through the use of fluid power technology. This concept considers a new way of generation, collection and transmission of wind energy inside a wind farm, in which electrical conversion does not occur during any

  6. Wind-driven estuarine turbidity maxima in Mandovi Estuary, central ...

    Indian Academy of Sciences (India)

    driven estuarine turbidity maxima in Mandovi Estuary, central west coast of India. Pratima M Kessarkar V Purnachandra Rao R Shynu Ishfaq Mir Ahmad Prakash Mehra G S Michael D Sundar. Volume 118 Issue 4 August 2009 pp 369-377 ...

  7. Electrically driven hybrid photonic metamaterials for multifunctional control

    Science.gov (United States)

    Kang, Lei; Liu, Liu; Campbell, Sawyer D.; Yue, Taiwei; Ren, Qiang; Mayer, Theresa S.; Werner, Douglas H.

    2017-08-01

    The unique light-matter interaction in metamaterials, a type of artificial medium in which the geometrical features of subunits dominate their optical responses, have been utilized to achieve exotic material properties that are rare or nonexistent in natural materials. Furthermore, to extend their behaviors, active materials have been introduced into metamaterial systems to advance tunability, switchability and nonlinearity. Nevertheless, practical examples of versatile photonic metamaterials remain exceedingly rare for two main reasons. On the one hand, in sharp contrast to the broad material options available at lower frequencies, it is less common to find active media in the optical regime that can provide pronounced dielectric property changes under external stimuli, such as electric and magnetic fields. Vanadium dioxide (VO2), offering a large refractive index variation over a broad frequency range due to its near room temperature insulator-to-metal transition (IMT), has been favored in recent studies on tunable metamaterials. On the other hand, it turns out that regulating responses of hybrid metamaterials to external forces in an integrated manner is not a straightforward task. Recently, metamaterial-enabled devices (i.e., metadevices) with `self-sufficient' or `self-contained' electrical and optical properties have enabled complex functionalities. Here, we present a design methodology along with the associated experimental validation of a VO2 thin film integrated optical metamaterial absorber as a hybrid photonic platform for electrically driven multifunctional control, including reflectance switching, a rewritable memory process and manageable localized camouflage. The nanoengineered topologically continuous metal structure simultaneously supports the optical resonance and electrical functionality that actuates the phase transition in VO2 through the process of Joule heating. This work provides a universal approach to creating self-sufficient and highly

  8. LCA of electricity systems with high wind power penetration

    DEFF Research Database (Denmark)

    Turconi, Roberto; O' Dwyer, C. O.; Flynn, D.

    Electricity systems are shifting from being based on fossil fuels towards renewable sources to enhance energy security and mitigate climate change. However, by introducing high shares of variable renewables - such as wind and solar - dispatchable power plants are required to vary their output...... storage capacity reduces system operating costs at high wind penetrations and limits cycling, the emissions reductions may be negated when coupled with base load coal....... assessment (LCA). Cycling emissions from dispatchable generators due to part-load operation and start-ups [3] were included for the first time in LCA. Part-load operations significantly affected the average power plant efficiency, with all units seeing an average yearly efficiency 1-11% lower than optimal...

  9. Transmission and wind investment in a deregulated electricity industry

    DEFF Research Database (Denmark)

    Maurovich-Horvat, Lajos; Boomsma, Trine Krogh; Siddiqui, Afzal S.

    2015-01-01

    Adoption of dispersed renewable energy technologies requires transmission network expansion. Besides the transmission system operator (TSO), restructuring of electricity industries has introduced a merchant investor (MI), who earns congestion rents from constructing new lines. We compare these two...... market designs via a stochastic bi-level programming model that has either the MI or the TSO making transmission investment decisions at the upper level and power producers determining generation investment and operation at the lower level while facing wind power variability. We find that social welfare...... is always higher under the TSO because the MI has incentive to boost congestion rents by restricting capacities of transmission lines. Such strategic behavior also limits investment in wind power by producers. However, regardless of the market design (MI or TSO), when producers behave à la Cournot, a higher...

  10. Transmission and wind investment in a deregulated electricity industry

    DEFF Research Database (Denmark)

    Maurovich-Horvat, Lajos; Boomsma, Trine Krogh; Fleten, Stein-Erik

    2013-01-01

    The transition to a more sustainable energy system requires investment in renewable energy technologies such as wind. Due to the dispersed nature of sites for wind farms, concomitant expansion of the transmission network is also necessary. While the two objectives could be reconciled within...... at the dominant demand node is to increase concentration of generation capacity. Hence, the distributional effects of transmission expansion depend on the relative supply-demand balance throughout the network....... the auspices of a regulated welfare-maximising planner, recent restructuring of electricity industries has introduced a merchant model for transmission investment, which provides congestion rents from construction of a new line. Thus, the merchant investor's incentives are different from those of producers...

  11. The Value of Wind Technology Innovation: Implications for the U.S. Power System, Wind Industry, Electricity Consumers, and Environment

    Energy Technology Data Exchange (ETDEWEB)

    Mai, Trieu T [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Lantz, Eric J [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Mowers, Matthew [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Wiser, Ryan [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2017-09-21

    Improvements to wind technologies have, in part, led to substantial deployment of U.S. wind power in recent years. The degree to which technology innovation will continue is highly uncertain adding to uncertainties in future wind deployment. We apply electric sector modeling to estimate the potential wind deployment opportunities across a range of technology advancement projections. The suite of projections considered span a wide range of possible cost and technology innovation trajectories, including those from a recent expert elicitation of wind energy experts, a projection based on the broader literature, and one reflecting estimates based on a U.S. DOE research initiative. In addition, we explore how these deployment pathways may impact the electricity system, electricity consumers, the environment, and the wind-related workforce. Overall, our analysis finds that wind technology innovation can have consequential implications for future wind power development throughout the United States, impact the broader electricity system, lower electric system and consumer costs, provide potential environmental benefits, and grow the U.S. wind workforce.

  12. High penetration wind generation impacts on spot prices in the Australian national electricity market

    Energy Technology Data Exchange (ETDEWEB)

    Cutler, Nicholas J., E-mail: nicholas.cutler@roamconsulting.com.au [School of Electrical Engineering and Telecommunications and Centre for Energy and Environmental Markets, University of New South Wales 2052, Sydney (Australia); Boerema, Nicholas D., E-mail: nicholas.boerema@student.unsw.edu.au [School of Photovoltaic and Renewable Energy Engineering and Centre for Energy and Environmental Markets, University of New South Wales, Sydney (Australia); MacGill, Iain F., E-mail: i.macgill@unsw.edu.au [School of Electrical Engineering and Telecommunications and Centre for Energy and Environmental Markets, University of New South Wales 2052, Sydney (Australia); Outhred, Hugh R., E-mail: h.outhred@unsw.edu.au [School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney (Australia)

    2011-10-15

    This paper explores wind power integration issues for the South Australian (SA) region of the Australian National Electricity Market (NEM) by assessing the interaction of regional wind generation, electricity demand and spot prices over 2 recent years of market operation. SA's wind energy penetration has recently surpassed 20% and it has only a limited interconnection with other regions of the NEM. As such, it represents an interesting example of high wind penetration in a gross wholesale pool market electricity industry. Our findings suggest that while electricity demand continues to have the greatest influence on spot prices in SA, wind generation levels have become a significant secondary influence, and there is an inverse relationship between wind generation and price. No clear relationship between wind generation and demand has been identified although some periods of extremely high demand may coincide with lower wind generation. Periods of high wind output are associated with generally lower market prices, and also appear to contribute to extreme negative price events. The results highlight the importance of electricity market and renewable policy design in facilitating economically efficient high wind penetrations. - Highlights: > In South Australia (SA) wind generation is having an influence on market prices. > Little or no correlation is found between wind generation and demand. > Wind farms in SA are receiving a lower average price than in other States. > The results highlight the importance of appropriate electricity market design.

  13. Hydrodynamic Models of Line-Driven Accretion Disk Winds III: Local Ionization Equilibrium

    Science.gov (United States)

    Pereyra, Nicolas Antonio; Kallman, Timothy R.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    We present time-dependent numerical hydrodynamic models of line-driven accretion disk winds in cataclysmic variable systems and calculate wind mass-loss rates and terminal velocities. The models are 2.5-dimensional, include an energy balance condition with radiative heating and cooling processes, and includes local ionization equilibrium introducing time dependence and spatial dependence on the line radiation force parameters. The radiation field is assumed to originate in an optically thick accretion disk. Wind ion populations are calculated under the assumption that local ionization equilibrium is determined by photoionization and radiative recombination, similar to a photoionized nebula. We find a steady wind flowing from the accretion disk. Radiative heating tends to maintain the temperature in the higher density wind regions near the disk surface, rather than cooling adiabatically. For a disk luminosity L (sub disk) = solar luminosity, white dwarf mass M(sub wd) = 0.6 solar mass, and white dwarf radii R(sub wd) = 0.01 solar radius, we obtain a wind mass-loss rate of M(sub wind) = 4 x 10(exp -12) solar mass yr(exp -1) and a terminal velocity of approximately 3000 km per second. These results confirm the general velocity and density structures found in our earlier constant ionization equilibrium adiabatic CV wind models. Further we establish here 2.5D numerical models that can be extended to QSO/AGN winds where the local ionization equilibrium will play a crucial role in the overall dynamics.

  14. Power System Modeling of 20% Wind-Generated Electricity by 2030: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Hand, M.; Blair, N.; Bolinger, M.; Wiser, R.; O' Connell, R.; Hern, T.; Miller, B.

    2008-06-01

    This paper shows the results of the Wind Energy Deployment System model used to estimate the costs and benefits associated with producing 20% of the nation's electricity from wind technology by 2030.

  15. Forecasting Electricity Spot Prices Accounting for Wind Power Predictions

    DEFF Research Database (Denmark)

    Jónsson, Tryggvi; Pinson, Pierre; Nielsen, Henrik Aalborg

    2013-01-01

    A two-step methodology for forecasting of electricity spot prices is introduced, with focus on the impact of predicted system load and wind power generation. The nonlinear and nonstationary influence of these explanatory variables is accommodated in a first step based on a nonparametric and time......-varying regression model. In a second step, time-series models, i.e., ARMA and Holt–Winters, are applied to account for residual autocorrelation and seasonal dynamics. Empirical results are presented for out-of-sample forecasts of day-ahead prices in the Western Danish price area of Nord Pool's Elspot, during a two...

  16. Improved electrical load match in California by combining solar thermal power plants with wind farms

    Science.gov (United States)

    The ability of wind and solar electrical energy generation to match the current utility electrical load in California was analyzed. We compared the renewable electrical generation and the utility load in California using actual hourly wind farm data at two different locations and predicted hourly p...

  17. 75 FR 61414 - Basin Electric Power Cooperative: South Dakota PrairieWinds Project

    Science.gov (United States)

    2010-10-05

    ... wind turbine generators; 6,000-square-foot operations and maintenance building and fence perimeter; 64... Rural Utilities Service Basin Electric Power Cooperative: South Dakota PrairieWinds Project AGENCY... Electric Power Cooperative's (Basin Electric) application for a RUS loan and a Western interconnection...

  18. IEMDC IN-LINE ELECTRIC MOTOR DRIVEN COMPRESSOR

    Energy Technology Data Exchange (ETDEWEB)

    Michael J. Crowley; Prem N. Bansal

    2004-10-01

    This report contains the final project summary and deliverables required by the award for the development of an In-line Electric Motor Driven Compressor (IEMDC). Extensive work was undertaken during the course of the project to develop the motor and the compressor section of the IEMDC unit. Multiple design iterations were performed to design an electric motor for operation in a natural gas environment and to successfully integrate the motor with a compressor. During the project execution, many challenges were successfully overcome in order to achieve the project goals and to maintain the system design integrity. Some of the challenges included limiting the magnitude of the compressor aerodynamic loading for appropriate sizing of the magnetic bearings, achieving a compact motor rotor size to meet the rotor dynamic requirements of API standards, devising a motor cooling scheme using high pressure natural gas, minimizing the impact of cooling on system efficiency, and balancing the system thrust loads for the magnetic thrust bearing. Design methods that were used on the project included validated state-of-the-art techniques such as finite element analysis and computational fluid dynamics along with the combined expertise of both Curtiss-Wright Electro-Mechanical Corporation and Dresser-Rand Company. One of the most significant areas of work undertaken on the project was the development of the unit configuration for the system. Determining the configuration of the unit was a significant step in achieving integration of the electric motor into a totally enclosed compression system. Product review of the IEMDC unit configuration was performed during the course of the development process; this led to an alternate design configuration. The alternate configuration is a modular design with the electric motor and compressor section each being primarily contained in its own pressure containing case. This new concept resolved the previous conflict between the aerodynamic flow

  19. Investigating Wind-Driven Rain Intrusion in Walls with the CARWASh

    Science.gov (United States)

    C.R. Boardman; Samuel V. Glass

    2013-01-01

    Wind-driven rain provides the primary external moisture load for exterior walls.Water absorption by the cladding, runoff, and penetration through the cladding or at details determine how a wall system performs. In this paper we describe a new laboratory facility that can create controlled outdoor and indoor conditions and use it to investigate the water...

  20. Wind-driven rain as a boundary condition for HAM simulations: analysis of simplified modelling approaches

    DEFF Research Database (Denmark)

    Janssen, Hans; Blocken, Bert; Roels, Staf

    2007-01-01

    While the numerical simulation of moisture transfer inside building components is currently undergoing standardisation, the modelling of the atmospheric boundary conditions has received far less attention. This article analyses the modelling of the wind-driven-rain load on building facades by par...

  1. Experimental Study of Wind-Opposed Buoyancy-Driven Natural Ventilation

    DEFF Research Database (Denmark)

    Andersen, A.; Bjerre, M.; Chen, Z. D.

    Natural ventilation driven by natural forces, i.e. wind and thermal buoyancy, is an environmentally friendly system for buildings and has been increasingly used around the world in recent years to mitigate the impact on the global environment due to the significant energy consumption by heating...

  2. A laboratory facility for research on wind-driven rain intrusion in building envelope assemblies

    Science.gov (United States)

    Samuel V. Glass

    2010-01-01

    Moisture management is critical for durable, energy-efficient buildings. To address the need for research on wind-driven rain intrusion in wall assemblies, the U.S. Forest Products Laboratory is developing a new facility. This paper describes the underlying principle of this facility and its capabilities.

  3. Final report: Task 4a.2 20% wind scenario assessment of electric grid operational features

    Energy Technology Data Exchange (ETDEWEB)

    Toole, Gasper L. [Los Alamos National Laboratory

    2009-01-01

    Wind integration modeling in electricity generation capacity expansion models is important in that these models are often used to inform political or managerial decisions. Poor representation of wind technology leads to under-estimation of wind's contribution to future energy scenarios which may hamper growth of the industry. The NREL's Wind Energy Deployment System (WinDS) model provides the most detailed representation of geographically disperse renewable resources and the optimization of transmission expansion to access these resources. Because WinDS was selected as the primary modeling tool for the 20% Wind Energy by 2030 study, it is the ideal tool for supplemental studies of the transmission expansion results. However, as the wind industry grows and knowledge related to the wind resource and integration of wind energy into the electric system develops, the WinDS model must be continually improved through additional data and innovative algorithms to capture the primary effects of variable wind generation. The detailed representation of wind technology in the WinDS model can be used to provide improvements to the simplified representation of wind technology in other capacity expansion models. This task did not employ the WinDS model, but builds from it and its results. Task 4a.2 provides an assessment of the electric grid operational features of the 20% Wind scenario and was conducted using power flow models accepted by the utility industry. Tasks 2 provides information regarding the physical flow of electricity on the electric grid which is a critical aspect of infrastructure expansion scenarios. Expanding transmission infrastructure to access remote wind resource in a physically realizable way is essential to achieving 20% wind energy by 2030.

  4. Analysis of wind driven self-excited induction generator supplying isolated DC loads

    Directory of Open Access Journals (Sweden)

    Khaled S. Sakkoury

    2017-05-01

    Full Text Available This paper presents the analysis, modelling and simulation of wind-driven self-excited induction generator (SEIG. The three-phase SEIG is driven by a variable-speed prime mover to represent a wind turbine. Also, the paper investigates the dynamic performance of the SEIG during start-up, increasing or decreasing the load or rotor speed. The value of the excitation capacitance required for the SEIG is calculated to give suitable saturation level to assure self-excitation and to avoid heavy saturation levels. Matching of the maximum power available from the wind turbine is performed through varying the load value. The effect of AC–DC power conversion on the generator is investigated. The system simulation is carried out using MATLAB/SIMULINK toolbox program.

  5. Wind energy for the electricity supply; Energie eolienne pour la fourniture d'electricite

    Energy Technology Data Exchange (ETDEWEB)

    Noel, J.M

    2009-01-15

    This document deals with the today implementing of the wind energy for the supply of electricity in the electric power distribution network. It is based on the technologies developed to prepare the wind turbines installation, build the turbines of these power plants and plan the non continuous and weakly forecasting supply of the wind electricity with the current operating of the networks. (A.L.B.)

  6. Invited article: Electric solar wind sail: toward test missions.

    Science.gov (United States)

    Janhunen, P; Toivanen, P K; Polkko, J; Merikallio, S; Salminen, P; Haeggström, E; Seppänen, H; Kurppa, R; Ukkonen, J; Kiprich, S; Thornell, G; Kratz, H; Richter, L; Krömer, O; Rosta, R; Noorma, M; Envall, J; Lätt, S; Mengali, G; Quarta, A A; Koivisto, H; Tarvainen, O; Kalvas, T; Kauppinen, J; Nuottajärvi, A; Obraztsov, A

    2010-11-01

    The electric solar wind sail (E-sail) is a space propulsion concept that uses the natural solar wind dynamic pressure for producing spacecraft thrust. In its baseline form, the E-sail consists of a number of long, thin, conducting, and centrifugally stretched tethers, which are kept in a high positive potential by an onboard electron gun. The concept gains its efficiency from the fact that the effective sail area, i.e., the potential structure of the tethers, can be millions of times larger than the physical area of the thin tethers wires, which offsets the fact that the dynamic pressure of the solar wind is very weak. Indeed, according to the most recent published estimates, an E-sail of 1 N thrust and 100 kg mass could be built in the rather near future, providing a revolutionary level of propulsive performance (specific acceleration) for travel in the solar system. Here we give a review of the ongoing technical development work of the E-sail, covering tether construction, overall mechanical design alternatives, guidance and navigation strategies, and dynamical and orbital simulations.

  7. Cyclotron instabilities driven by temperature anisotropy in the solar wind

    Science.gov (United States)

    Noreen, N.; Yoon, P. H.; Zaheer, S.

    2017-10-01

    Kinetic plasma instabilities are important for regulating the temperature anisotropies of electrons and ions in solar wind. For the low beta regime, it is known that electromagnetic ion/electron cyclotron instabilities are important, but in the literature these unstable modes are discussed under the assumption of parallel propagation. The present paper extends the analysis to two (or with cylindrical symmetry, three) dimensions. The analysis is further extended to include quasilinear description with the assumption of the bi-Maxwellian velocity distribution function. Such an analysis lays the foundation for an eventual study in which cyclotron instabilities as well as obliquely propagating unstable modes such as the mirror instability are simultaneously taken into account. The present paper first lays down the basis for such future efforts in which the two- or three dimensional linear and quasilinear theories of cyclotron instabilities in the low beta regime are formulated.

  8. Natural Ventilation Driven by Wind and Temperature Difference

    DEFF Research Database (Denmark)

    Larsen, Tine Steen

    Natural ventilation is a commonly used principle when buildings are being ventilated. It can be controlled by openings in the building envelope, which open or close depending on the need of air inside the building. It can also be the simple action of just opening a door or a window to let the fresh...... air in. In both cases it is often necessary to have an idea of the amount of air coming through the window. Therefore, expressions for this prediction have been developed through the last decades. In cross-ventilation, the expressions are rather well defined and here the difficulty lies within...... the definition of the discharge coefficient that describes the characteristics of the opening, since it seems to fluctuate depending on the incidence angle of the wind. In single-sided ventilation where openings only exist in one side of the building, the flow through the opening is harder to predict. The main...

  9. Wind-driven rain and its implications for natural hazard management

    Science.gov (United States)

    Marzen, Miriam; Iserloh, Thomas; de Lima, João L. M. P.; Fister, Wolfgang; Ries, Johannes B.

    2017-04-01

    Prediction and risk assessment of hydrological extremes are great challenges. Following climate predictions, frequent and violent rainstorms will become a new hazard to several regions in the medium term. Particularly agricultural soils will be severely threatened due to the combined action of heavy rainfall and accompanying winds on bare soil surfaces. Basing on the general underestimation of the effect of wind on rain erosion, conventional soil erosion measurements and modeling approaches lack related information to adequately calculate its impact. The presented experimental-empirical approach shows the powerful impact of wind on the erosive potential of rain. The tested soils had properties that characterise three different environments 1. Silty loam of semi-arid Mediterranean dryfarming and fallow, 2. clayey loam of humid agricultural sites and 3. cohesionless sandy substrates as found at coasts, dune fields and drift-sand areas. Erosion was found to increase by a factor of 1.3 to 7.1, depending on site characteristics. Complementary tests with a laboratory procedure were used to quantify explicitly the effect of wind on raindrop erosion as well as the influence of substrate, surface structure and slope on particle displacement. These tests confirmed the impact of wind-driven rain on total erosion rates to be of great importance when compared to all other tested factors. To successfully adapt soil erosion models to near-future challenges of climate change induced rain storms, wind-driven rain is supposed to be introduced into the hazard management agenda.

  10. Differential stemflow generation due to crown structural interactions with wind-driven rainfall

    Science.gov (United States)

    Van Stan, John; Siegert, Courtney; Levia, Delphis; Scheick, Carrie

    2013-04-01

    Meteorological influences on the variability of stemflow generation can affect the hydrology, ecology and soil chemistry of wooded ecosystems, yet the effects of directional wind-driven rainfall on differential stemflow production remain relatively un-researched. This study examines the correspondence of directional wind-driven inclined rainfall with stemflow generation in individual tree crowns utilizing multiple correspondence analysis (MCA) and intrastorm observations at 5 min monitoring intervals. In general, preferential stemflow generation at Fair Hill was observed during episodes of inclined rainfall driven by wind from the east to north-northeast (33.76-101.25 deg.). This was supported by MCAs which produced significant correspondences between stemflow production and periods of inclined wind-driven rainfall for nearly all monitored storm events. Intrastorm plots of stemflow production from dominant and subcanopy trees of each codominant species (Fagus grandifolia Ehrh. (American beech) and Liriodendron tulipifera L. (yellow poplar)) also verified this correspondence. Interspecific canopy characteristics of L. tulipifera and F. grandifolia affected crown position, canopy structural characteristics, and, thus, the canopy's response to inclined precipitation. The greater vertical canopy depth observed for F. grandifolia trees enabled them to more efficiently capture inclined rainfall for enhanced stemflow production; whereas, the greater horizontal surface area of L. tulipifera canopies enhanced their droplet capture efficiency and subsequent stemflow generation for periods of un-inclined rainfall. As inclined wind-driven rainfall occurred within a majority of rain events at this site, preferential stemflow production may be a significant process to consider when examining the spatial distribution of canopy-derived water fluxes to the forest floor of wooded catchments under similar meteorological conditions.

  11. Sun, wind and electric generation; Sol, viento y generacion electrica

    Energy Technology Data Exchange (ETDEWEB)

    Huacuz Villamar, Jorge M. [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1995-12-31

    A description is made of the electric generation known as the photovoltaic-wind power hybrid systems at the generation station of X-Calak which is located in the zone known as Punta Herrero-X-Calak Corridor, in the Southern coast of the Quintana Roo State. This is a technology in development, in which the solar and the wind energy are combined, to offer an alternative of electric generation that can be economical, reliable and of low impact on the environment. Mention is made of the experiences gathered in this station as well as the results obtained [Espanol] Se describe la tecnologia de generacion electrica conocida como sistemas hibridos fotovoltaico-eolico en la planta generadora de X-Calak, la cual esta localizada en la zona conocida como el corredor Punta Herrero-X-Calak, en la costa sur del estado de Quintana Roo. Esta es una tecnologia en desarrollo, en donde se combina la energia solar y energia eolica, para ofrecer una alternativa de generacion electrica que pretende ser economica, confiable y de bajo impacto sobre el medio ambiente. Se mencionan las experiencias obtenidas en esta planta asi como los resultados obtenidos

  12. 3D Electric Waveforms of Solar Wind Turbulence

    Science.gov (United States)

    Kellogg, P. J.; Goetz, K.; Monson, S. J.

    2018-01-01

    Electric fields provide the major coupling between the turbulence of the solar wind and particles. A large part of the turbulent spectrum of fluctuations in the solar wind is thought to be kinetic Alfvén waves; however, whistlers have recently been found to be important. In this article, we attempt to determine the mode identification of individual waveforms using the three-dimensional antenna system of the SWaves experiments on the STEREO spacecraft. Samples are chosen using waveforms with an apparent periodic structure, selected visually. The short antennas of STEREO respond to density fluctuations and to electric fields. Measurement of four quantities using only three antennas presents a problem. Methods to overcome or to ignore this difficulty are presented. We attempt to decide whether the waveforms correspond to the whistler mode or the Alfvén mode by using the direction of rotation of the signal. Most of the waveforms are so oblique—nearly linearly polarized—that the direction cannot be determined. However, about one third of the waveforms can be identified, and whistlers and Alfvén waves are present in roughly equal numbers. The selected waveforms are very intense but intermittent and are orders of magnitude stronger than the average, yet their accumulated signal accounts for a large fraction of the average. The average, however, is supposed to be the result of a turbulent mixture of many waves, not short coherent events. This presents a puzzle for future work.

  13. Wind-driven Water Bodies : a new paradigm for lake geology

    Science.gov (United States)

    Nutz, A.; Schuster, M.; Ghienne, J. F.; Roquin, C.; Bouchette, F. A.

    2015-12-01

    In this contribution we emphasize the importance in some lakes of wind-related hydrodynamic processes (fair weather waves, storm waves, and longshore, cross-shore and bottom currents) as a first order forcing for clastics remobilization and basin infill. This alternative view contrasts with more classical depositional models for lakes where fluvial-driven sedimentation and settling dominates. Here we consider three large lakes/paleo-lakes that are located in different climatic and geodynamic settings: Megalake Chad (north-central Africa), Lake Saint-Jean (Québec, Canada), and Lake Turkana (Kenya, East African Rift System). All of these three lake systems exhibit well developed modern and ancient high-energy littoral morphosedimentary structures which directly derive from wind-related hydrodynamics. The extensive paleo-shorelines of Megalake Chad are composed of beach-foredune ridges, spits, wave-dominated deltas, barriers, and wave-ravinment surface. For Lake Saint-Jean the influence of wind is also identified below the wave-base at lake bottom from erosional surfaces, and sediment drifts. In the Lake Turkana Basin, littoral landforms and deposits are identified for three different time intervals (today, Holocene, Plio-Pleistocene) evidencing that wind-driven hydrodynamics can be preserved in the geological record. Moreover, a preliminary global survey suggests that numerous modern lakes (remote sensing) and paleo-lakes (bibliographic review) behave as such. We thus coin the term "Wind-driven Water Bodies" (WWB) to refer to those lake systems where sedimentation (erosion, transport, deposition) is dominated by wind-induced hydrodynamics at any depth, as it is the case in the marine realm for shallow seas. Integrating wind forcing in lake models has strong implications for basin analysis (paleoenvironments and paleoclimates restitutions, resources exploration), but also for coastal engineering, wildlife and reservoirs management, or leisure activities.

  14. Wind-driven coastal upwelling and westward circulation in the Yucatan shelf

    Science.gov (United States)

    Ruiz-Castillo, Eugenio; Gomez-Valdes, Jose; Sheinbaum, Julio; Rioja-Nieto, Rodolfo

    2016-04-01

    The wind-driven circulation and wind-induced coastal upwelling in a large shelf sea with a zonally oriented coast are examined. The Yucatan shelf is located to the north of the Yucatan peninsula in the eastern Gulf of Mexico. This area is a tropical shallow body of water with a smooth sloping bottom and is one of the largest shelves in the world. This study describes the wind-driven circulation and wind-induced coastal upwelling in the Yucatan shelf, which is forced by easterly winds throughout the year. Data obtained from hydrographic surveys, acoustic current profilers and environmental satellites are used in the analysis. Hydrographic data was analyzed and geostrophic currents were calculated in each survey. In addition an analytical model was applied to reproduce the currents. The results of a general circulation model were used with an empirical orthogonal function analysis to study the variability of the currents. The study area is divided in two regions: from the 40 m to the 200 m isobaths (outer shelf) and from the coast to the 40 m isobath (inner shelf). At the outer shelf, observations revealed upwelling events throughout the year, and a westward current with velocities of approximately 0.2 m s-1 was calculated from the numerical model output and hydrographic data. In addition, the theory developed by Pedlosky (2007) for a stratified fluid along a sloping bottom adequately explains the current's primary characteristics. The momentum of the current comes from the wind, and the stratification is an important factor in its dynamics. At the inner shelf, observations and numerical model output show a wind-driven westward current with maximum velocities of 0.20 m s-1. The momentum balance in this region is between local acceleration and friction. A cold-water band is developed during the period of maximum upwelling.

  15. PROVIDING QUALITY OF ELECTRIC POWER IN ELECTRIC POWER SYSTEM IN PARALLEL OPERATION WITH WIND TURBINE

    Directory of Open Access Journals (Sweden)

    Yu. A. Rolik

    2016-01-01

    Full Text Available The problem of providing electric power quality in the electric power systems (EPS that are equipped with sufficiently long air or cable transmission lines is under consideration. This problem proved to be of particular relevance to the EPS in which a source of electrical energy is the generator of wind turbines since the wind itself is an instable primary energy source. Determination of the degree of automation of voltage regulation in the EPS is reduced to the choice of methods and means of regulation of power quality parameters. The concept of a voltage loss and the causes of the latter are explained by the simplest power system that is presented by a single-line diagram. It is suggested to regulate voltage by means of changing parameters of the network with the use of the method of reducing loss of line voltage by reducing its reactance. The latter is achieved by longitudinal capacitive compensation of the inductive reactance of the line. The effect is illustrated by vector diagrams of currents and voltages in the equivalent circuits of transmission lines with and without the use of longitudinal capacitive compensation. The analysis of adduced formulas demonstrated that the use of this method of regulation is useful only in the systems of power supply with a relatively low power factor (cosφ < 0.7 to 0.9. This power factor is typical for the situation of inclusion the wind turbine with asynchronous generator in the network since the speed of wind is instable. The voltage regulation fulfilled with the aid of the proposed method will make it possible to provide the required quality of the consumers’ busbars voltage in this situation. In is turn, it will make possible to create the necessary conditions for the economical transmission of electric power with the lowest outlay of reactive power and the lowest outlay of active power losses.

  16. Application of amodal-driven damage assessmentframework for ice localization andquantification on wind turbine blades

    DEFF Research Database (Denmark)

    Hansen, J.B.; Brincker, Rune; Glavind, L.

    2017-01-01

    Operating wind turbines in northern and/or mountainous regions create the demand for effective ice detection and ice removal systems. Ice accretion on the rotor blades of a wind turbine leads, among other things, to added loads, safety issues and diminished aerodynamic performance of the airfoil....... Presently, the capabilities of existing ice detection techniques are limited to determining whether or not ice is present on the blades. This paper presents a feasibility investigation of the implementation of a recent scenario-based modal-driven damage detection, localization and quantification technique...... for ice detection on a wind turbine blade. The investigation is experimentally founded and consists of a series of full-scale modal tests on a modern wind turbine blade mounted in a fixed test rig. Throughout the test campaign the modal parameters are extracted by means of an automated Operational Modal...

  17. Integrating wind output with bulk power operations and wholesale electricity markets

    Energy Technology Data Exchange (ETDEWEB)

    Hirst, E. [Consulting in Electric-Industry Restructuring, Oak Ridge, TN (United States)

    2002-07-01

    Wind farms have three characteristics that complicate their widespread application as an electricity resource: limited control, unpredictability and variability. Therefore the integration of wind output into bulk power electric systems is qualitatively different from that of other types of generators. The electric system operator must move other generators up or down to offset the time-varying wind fluctuations. Such movements raise the costs of fuel and maintenance for these other generators. Not only is wind power different, it is new. The operators of bulk power systems have limited experience in integrating wind output into the larger system. As a consequence, market rules that treat wind fairly - neither subsidizing nor penalizing its operation - have not yet been developed. The lack of data and analytical methods encourages wind advocates and sceptics to rely primarily on their biases and beliefs in suggesting how wind should be integrated into bulk power systems. This project helps fill this data and analysis gap. Specifically, it develops and applies a quantitative method for the integration of a wind resource into a large electric system. The method permits wind to bid its output into a short-term forward market (specifically, an hour-ahead energy market) or to appear in real time and accept only intrahour and hourly imbalance payments for the unscheduled energy it delivers to the system. Finally, the method analyses the short-term (minute-to-minute) variation in wind output to determine the regulation requirement the wind resource imposes on the electrical system. (author)

  18. Simulation Tool to Assess Mechanical and Electrical Stresses on Wind Turbine Generators: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Singh, M.; Muljadi, E.; Gevorgian, V.; Jonkman, J.

    2013-10-01

    Wind turbine generators (WTGs) consist of many different components to convert kinetic energy of the wind into electrical energy for end users. Wind energy is accessed to provide mechanical torque for driving the shaft of the electrical generator. The conversion from wind power to mechanical power is governed by the aerodynamic conversion. The aerodynamic-electrical-conversion efficiency of a WTGis influenced by the efficiency of the blades, the gearbox, the generator, and the power converter. This paper describes the use of MATLAB/Simulink to simulate the electrical and grid-related aspects of a WTG coupled with the FAST aero-elastic wind turbine computer-aided engineering tool to simulate the aerodynamic and mechanical aspects of a WTG. The combination of the two enables studiesinvolving both electrical and mechanical aspects of a WTG. This digest includes some examples of the capabilities of the FAST and MATLAB coupling, namely the effects of electrical faults on the blade moments.

  19. Determination of recoverable wind energy for electricity generation ...

    African Journals Online (AJOL)

    The Weibull distribution functions and the Betz theory are applied to describe the wind speed distribution and to determinate the wind power density for these sites. Also, mathematical models are used to calculate the recoverable wind power and the wind energy produced by a wind turbine. According to the power ...

  20. Wind power systems for individual applications. [electric power supplies for homes

    Science.gov (United States)

    Clews, H. M.

    1973-01-01

    A small windpower system is described which is suitable for electrifying a house. The self-contained unit consists of a two kilowatt wind driven generator, a set of 19 storage batteries, a small dc to ac inverter, and a gasoline generator for use as an emergency backup system in case of prolonged calm periods. Cost effectiveness of the electricity generated by this windmill system comes out to about 15 cents per kilowatt hour - assuming a 10 year life for the batteries and a 20 year life for the other components. Some other small windpower systems are also described, and it is shown that a windpowered generator in the 15- to 25-kilowatt output range coupled to a direct heated water storage system is able to heat a typical New England home.

  1. 75 FR 6020 - Electrical Interconnection of the Lower Snake River Wind Energy Project

    Science.gov (United States)

    2010-02-05

    ... Bonneville Power Administration Electrical Interconnection of the Lower Snake River Wind Energy Project... Puget Sound Energy Inc., a Large Generator Interconnection Agreement for interconnection of up to 1250... their proposed Lower Snake River Wind Energy Project (Wind Project) in Garfield and Columbia counties...

  2. A study of wind energy potential: remedy for fluctuation of electric ...

    African Journals Online (AJOL)

    Aside, wind energy is a renewable source of energy and it is environmentally friendly which conforms to the national energy and environmental policy of Nigeria with respect to the new world order of economic development and environmental sustainability. Keywords: wind energy potential, electric power fluctuation, wind ...

  3. EMMI-Electric solar wind sail facilitated Manned Mars Initiative

    Science.gov (United States)

    Janhunen, Pekka; Merikallio, Sini; Paton, Mark

    2015-08-01

    The novel propellantless electric solar wind sail concept promises efficient low thrust transportation in the Solar System outside Earth's magnetosphere. Combined with asteroid mining to provide water and synthetic cryogenic rocket fuel in orbits of Earth and Mars, possibilities for affordable continuous manned presence on Mars open up. Orbital fuel and water enable reusable bidirectional Earth-Mars vehicles for continuous manned presence on Mars and allow smaller fuel fraction of spacecraft than what is achievable by traditional means. Water can also be used as radiation shielding of the manned compartment, thus reducing the launch mass further. In addition, the presence of fuel in the orbit of Mars provides the option for an all-propulsive landing, thus potentially eliminating issues of heavy heat shields and augmenting the capability of pinpoint landing. With this E-sail enabled scheme, the recurrent cost of continuous bidirectional traffic between Earth and Mars might ultimately approach the recurrent cost of running the International Space Station, ISS.

  4. Analysis methods for wind turbine control and electrical system dynamics

    Science.gov (United States)

    Hinrichsen, E. N.

    1995-01-01

    The integration of new energy technologies into electric power systems requires methods which recognize the full range of dynamic events in both the new generating unit and the power system. Since new energy technologies are initially perceived as small contributors to large systems, little attention is generally paid to system integration, i.e. dynamic events in the power system are ignored. As a result, most new energy sources are only capable of base-load operation, i.e. they have no load following or cycling capability. Wind turbines are no exception. Greater awareness of this implicit (and often unnecessary) limitation is needed. Analysis methods are recommended which include very low penetration (infinite bus) as well as very high penetration (stand-alone) scenarios.

  5. Small Wind Electric Systems: A U.S. Consumer's Guide

    Energy Technology Data Exchange (ETDEWEB)

    None

    2007-08-01

    The handbook provides consumers with information to help them determine whether a small wind electric system can provide all or a portion of the energy they need for their home or business based on their wind resource, energy needs, and their economics. Topics discussed in the guide include how to make a home more energy efficient, how to choose the correct turbine size, the parts of a wind electric system, how to determine whether enough wind resource exists, how to choose the best site for a turbine, how to connect a system to the utility grid, and whether it's possible to become independent of the utility grid using wind energy.

  6. Influence of wind power, plug-in electric vehicles, and heat storages on power system investments

    DEFF Research Database (Denmark)

    Kiviluoma, Juha; Meibom, Peter

    2010-01-01

    Due to rising fuel costs, the substantial price for CO2 emissions and decreasing wind power costs, wind power might become the least expensive source of power for an increasing number of power systems. This poses the questions of how wind power might change optimal investments in other forms...... electric vehicles. The model runs in an hourly time scale in order to accommodate the impact of variable power production from wind power. Electric vehicles store electricity for later use and can thus serve to increase the flexibility of the power system. Flexibility can also be upgraded by using heat...

  7. Small Wind Electric Systems: A Guide Produced for the Tennessee Valley Authority (Revised) (Brochure)

    Energy Technology Data Exchange (ETDEWEB)

    2009-06-01

    Small Wind Electric Systems: A Guide Produced for the Tennessee Valley Authority provides consumers with information to help them determine whether a small wind electric system can provide all or a portion of the energy they need for their home or business based on their wind resource, energy needs, and their economics. Topics discussed in the guide include how to make a home more energy efficient, how to choose the correct turbine size, the parts of a wind electric system, how to determine whether enough wind resource exists, how to choose the best site for a turbine, how to connect a system to the utility grid, and whether it's possible to become independent of the utility grid using wind energy. In addition, the cover of the guide contains a regional wind resource map and a list of incentives and contacts for more information.

  8. Small Wind Electric Systems: An Idaho Consumer's Guide (Revised)

    Energy Technology Data Exchange (ETDEWEB)

    2004-08-01

    Small Wind Electric Systems: An Idaho Consumer's Guide provides consumers with information to help them determine whether a small wind electric system can provide all or a portion of the energy they need for their home or business based on their wind resource, energy needs, and their economics. Topics discussed in the guide include how to make a home more energy efficient, how to choose the correct turbine size, the parts of a wind electric system, how to determine whether enough wind resource exists, how to choose the best site for a turbine, how to connect a system to the utility grid, and whether it's possible to become independent of the utility grid using wind energy. In addition, the cover of the guide contains a regional wind resource map and a list of incentives and contacts for more information.

  9. Small Wind Electric Systems: A New York Consumer's Guide

    Energy Technology Data Exchange (ETDEWEB)

    2005-02-01

    Small Wind Electric Systems: A New York Consumer's Guide provides consumers with information to help them determine whether a small wind electric system can provide all or a portion of the energy they need for their home or business based on their wind resource, energy needs, and their economics. Topics discussed in the guide include how to make a home more energy efficient, how to choose the correct turbine size, the parts of a wind electric system, how to determine whether enough wind resource exists, how to choose the best site for a turbine, how to connect a system to the utility grid, and whether it's possible to become independent of the utility grid using wind energy. In addition, the cover of the guide contains a regional wind resource map and a list of incentives and contacts for more information.

  10. Small Wind Electric Systems: A Maryland Consumer's Guide (Revised)

    Energy Technology Data Exchange (ETDEWEB)

    2009-08-01

    Small Wind Electric Systems: A Maryland Consumer's Guide provides consumers with information to help them determine whether a small wind electric system can provide all or a portion of the energy they need for their home or business based on their wind resource, energy needs, and their economics. Topics discussed in the guide include how to make a home more energy efficient, how to choose the correct turbine size, the parts of a wind electric system, how to determine whether enough wind resource exists, how to choose the best site for a turbine, how to connect a system to the utility grid, and whether it's possible to become independent of the utility grid using wind energy. In addition, the cover of the guide contains a regional wind resource map and a list of incentives and contacts for more information.

  11. Wind power integration studies using a multi-stage stochastic electricity system model

    DEFF Research Database (Denmark)

    Meibom, Peter; Barth, R.; Brand, H.

    2007-01-01

    A large share of integrated wind power causes technical and financial impacts on the operation of the existing electricity system due to the fluctuating behaviour and unpredictability of wind power. The presented stochastic electricity market model optimises the unit commitment considering four...

  12. NWTC Aerodynamics Studies Improve Energy Capture and Lower Costs of Wind-Generated Electricity

    Energy Technology Data Exchange (ETDEWEB)

    2015-08-01

    Researchers at the National Wind Technology Center (NWTC) at the National Renewable Energy Laboratory (NREL) have expanded wind turbine aerodynamic research from blade and rotor aerodynamics to wind plant and atmospheric inflow effects. The energy capture from wind plants is dependent on all of these aerodynamic interactions. Research at the NWTC is crucial to understanding how wind turbines function in large, multiple-row wind plants. These conditions impact the cumulative fatigue damage of turbine structural components that ultimately effect the useful lifetime of wind turbines. This work also is essential for understanding and maximizing turbine and wind plant energy production. Both turbine lifetime and wind plant energy production are key determinants of the cost of wind-generated electricity.

  13. Electric field driven switching of individual magnetic skyrmions (Conference Presentation)

    Science.gov (United States)

    Hsu, Pin-Jui

    2016-10-01

    An interesting class of interface-driven non-collinear spin structures, i.e., chiral domain walls, cycloidal spin spirals and Néel-type skyrmions, have been observed in ultrathin transition metal films grown on heavy-element substrates making use of spin-polarized scanning tunneling microscopy (SP-STM) [1]. Due to a lack of structural inversion symmetry at interfaces, they exhibit a unique rotational sense as a consequence of interfacial Dzyaloshinskii-Moriya (DM) interactions. In this talk, I will present our results based on the investigations of such chiral spin textures under the influence of strain relief and the effect of local electric fields. While a nanoskyrmion lattice was revealed for Fe monolayers (ML) grown on Ir(111), a cycloidal spin spiral ground state has been resolved on Fe double-layers (DL) by employing SP-STM with vectorial magnetic field. As a result of a large lattice mismatch between the epitaxially grown Fe-DL film and the underlying Ir(111) substrate, local uniaxial strain relief occurs, leading to dislocation line patterns. Interestingly, the wavevector of spin spirals is strictly guided along the dislocation lines, while the spin spiral's wavefront exhibits a zigzag deformation [2]. By further increasing the Fe coverage to triple-layers (TL), the zigzag spin spiral remains the magnetic ground state, but with an enhanced periodicity as compared to that of Fe-DL. A magnetic phase transition from the spin spiral to a skyrmionic state, and finally to a saturated ferromagnetic state occurs for Fe-TL by applying an external magnetic field. STM-induced writing and deleting of individual skyrmions is demonstrated with a pronounced bias-polarity dependence, suggesting the decisive role of the local electric field between STM tip and Fe film for the switching mechanism [3]. [1] K. von Bergmann, A. Kubetzka, O. Pietzsch, and R. Wiesendanger, J. Phys.: Condens. Matter 26, 394002 (2014) [2] P.-J. Hsu, A. Finco, L. Schmidt, A. Kubetzka, K. von

  14. Evaluation of Discharge Coefficients for Window Openings in Wind Driven Natural Ventilation

    DEFF Research Database (Denmark)

    Heiselberg, Per; Sandberg, Mats

    2006-01-01

    This paper describes the classical approach for calculation of wind driven airflow through large openings in buildings and discusses the fulfilment of the limiting assumptions. It is demonstrated that the limiting assumptions are not fulfilled for large openings in buildings for cross ventilation...... cannot be regarded as a constant and it is very difficult to estimate correct values resulting in less accuracy of prediction of natural ventilation.......This paper describes the classical approach for calculation of wind driven airflow through large openings in buildings and discusses the fulfilment of the limiting assumptions. It is demonstrated that the limiting assumptions are not fulfilled for large openings in buildings for cross ventilation......, and therefore, the classical approach is not appropriate for prediction of airflow through large openings in buildings in the cross ventilation case. Using the approach for real openings and estimating the discharge coefficient for window openings has also not been very successful. The discharge coefficient...

  15. Application of genetic algorithm in electrical system optimization for offshore wind farms

    DEFF Research Database (Denmark)

    Chen, Zhe; Zhao, M.; Blaabjerg, Frede

    2008-01-01

    Genetic Algorithm (GA) has been widely used in solving optimization problem in different areas. This paper illustrates the application of GA in the electrical system design for offshore wind farms, where the main components of a wind farm and key technical specifications are used as input...... parameters and the electrical system design of the wind farm is to be optimized regarding both the production cost and the system reliability....

  16. Selected Aspects Of Building, Operation And Environmental Impact Of Offshore Wind Power Electric Plants

    Directory of Open Access Journals (Sweden)

    Mroziński Adam

    2015-04-01

    Full Text Available This paper describes essence of work of offshore wind power electric plants and crucial aspects of their building and operating. Prospects for development of global, European and domestic markets of offshore wind power industry have been delineated. A comparative analysis of environmental impact of an offshore and land-based 2MW wind power electric plant has been performed by using LCA method and Ecoindex – 99 (Ekowskaźnik 99 modelling.

  17. Wind driven upwelling along the African coast of the Strait of Gibraltar

    Science.gov (United States)

    Stanichny, S.; Tigny, V.; Stanichnaya, R.; Djenidi, S.

    2005-02-01

    Regular remote sensing data from various sensors are used here for the study of the wind driven upwelling phenomenon along the African coast of the Strait of Gibraltar. It is shown for an extended summer period (May 15 till September 15, 2003) that sea surface temperature (SST) data in the strait are correlated with NCEP winds, each westward wind increase being followed by a clear surface temperature decrease. Local surface temperature of about 22°C at that time drops down to 15°C, value corresponding to the 80-120 m depth conditions. The analysis of subsequent images indicates that the cold upwelling plume typically moves first to the Atlantic during wind forcing, and then to the Mediterranean after the wind event. The presence of the northern coast of the strait is taken as responsible for a rise of a cross-strait sea level gradient and the enhancement of the associated westward geostrophic current that explains the first stage of the plume deployment. Sea level difference measured between Tarifa (European coast) and Ceuta (African coast), well described by a linear equation in term of the westward wind component, supports this idea as well as the subsequent remotely sensed SST distributions.

  18. Modeling X-ray Absorbers in AGNs with MHD-Driven Accretion-Disk Winds

    Science.gov (United States)

    Fukumura, Keigo; Kazanas, D.; Shrader, C. R.; Tombesi, F.; Contopoulos, J.; Behar, E.

    2013-04-01

    We have proposed a systematic view of the observed X-ray absorbers, namely warm absorbers (WAs) in soft X-ray and highly-ionized ultra-fast outflows (UFOs), in the context of magnetically-driven accretion-disk wind models. While potentially complicated by variability and thermal instability in these energetic outflows, in this simplistic model we have calculated 2D kinematic field as well as density and ionization structure of the wind with density profile of 1/r corresponding to a constant column distribution per decade of ionization parameter. In particular we show semi-analytically that the inner layer of the disk-wind manifests itself as the strongly-ionized fast outflows while the outer layer is identified as the moderately-ionized absorbers. The computed characteristics of these two apparently distinct absorbers are consistent with X-ray data (i.e. a factor of ~100 difference in column and ionization parameters as well as low wind velocity vs. near-relativistic flow). With the predicted contour curves for these wind parameters one can constrain allowed regions for the presence of WAs and UFOs.The model further implies that the UFO's gas pressure is comparable to that of the observed radio jet in 3C111 suggesting that the magnetized disk-wind with density profile of 1/r is a viable agent to help sustain such a self-collimated jet at small radii.

  19. Excessive price reduction and extreme volatility in wind dominant electricity markets; solutions and emerging challenges

    DEFF Research Database (Denmark)

    Farashbashi-Astaneh, Seyed-Mostafa; Chen, Zhe; Mousavi, Omid Alizadeh

    2013-01-01

    is developed. The paper indicates discriminatory pricing approach can be beneficial in high penetration of wind power because it alleviates high price variations and spikiness in one hand and prevents overmuch price reduction in wind dominant electricity markets on the other hand.......High intermittency in the nature of wind power emphasize conceptual revising in the mechanisms of electricity markets with high wind power penetration levels. This paper introduces overmuch price reduction and high price volatility as two adverse consequences in future wind dominant electricity...... markets. While high price volatility imposes elevated risk levels for both electricity suppliers and consumers, excessive price reduction of electricity is a disincentive for investment in new generation capacity and might jeopardizes system adequacy in long term. A comparative study between marginal...

  20. Development of advanced winding condition control technology of electric motors based on pulsed method

    Directory of Open Access Journals (Sweden)

    Alexey V. Mytnikov

    2017-09-01

    Full Text Available More than 80 percent of all electrical energy customers are electric motors. Therefore one of the prospects of resource-effective technologies in power industry is control of rotating electric equipment condition. Winding defects are one of the main causes of electric motor failures. Reliable control of winding condition is an urgent task of modern electrical engineering technology. The present article is devoted to the research of pulsed method application of transformer winding control for electric motor winding condition control. The procedure of winding condition control technology is described. The proposed method is based on the known pulsed method. The essential difference between the two methods is that only one probing impulse is used which is a probing impulse and response signal at once. The results of diagnostic procedure research at different winding defects are given. It is established that the place of winding damage corresponds to characteristic impulse changes. The defect of definite types causes specific changes of the probing impulse form. Therefore, different winding defects could be found with high accuracy along winding.

  1. New Solutions to Line-Driven Winds of Hot Massive Stars

    Science.gov (United States)

    Gormaz-Matamala, Alex C.; Curé, Michel; Cidale, Lydia; Venero, Roberto

    2017-11-01

    In the frame of radiation driven wind theory (Castor et al.1975), we present self-consistent hydrodynamical solutions to the line-force parameters (k, α, δ) under LTE conditions. Hydrodynamic models are provided by HydWind (Curé 2004). We evaluate these results with those ones previously found in literature, focusing in different regions of the optical depth to be used to perform the calculations. The values for mass-loss rate and terminal velocity obtained from our calculations are also presented. We also examine the line-force parameters for the case when large changes in ionization throughout the wind occurs (δ-slow solutions, Curé et al.2011).

  2. Maximum power extraction under different vector-control schemes and grid-synchronization strategy of a wind-driven Brushless Doubly-Fed Reluctance Generator.

    Science.gov (United States)

    Mousa, Mohamed G; Allam, S M; Rashad, Essam M

    2018-01-01

    This paper proposes an advanced strategy to synchronize the wind-driven Brushless Doubly-Fed Reluctance Generator (BDFRG) to the grid-side terminals. The proposed strategy depends mainly upon determining the electrical angle of the grid voltage, θ v and using the same transformation matrix of both the power winding and grid sides to ensure that the generated power-winding voltage has the same phase-sequence of the grid-side voltage. On the other hand, the paper proposes a vector-control (power-winding flux orientation) technique for maximum wind-power extraction under two schemes summarized as; unity power-factor operation and minimum converter-current. Moreover, a soft-starting method is suggested to avoid the employed converter over-current. The first control scheme is achieved by adjusting the command power-winding reactive power at zero for a unity power-factor operation. However, the second scheme depends on setting the command d-axis control-winding current at zero to maximize the ratio of the generator electromagnetic-torque per the converter current. This enables the system to get a certain command torque under minimum converter current. A sample of the obtained simulation and experimental results is presented to check the effectiveness of the proposed control strategies. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

  3. A wind-driven nonseasonal barotropic fluctuation of the Canadian inland seas

    Directory of Open Access Journals (Sweden)

    C. G. Piecuch

    2015-02-01

    Full Text Available A wind-driven, spatially coherent mode of nonseasonal, depth-independent variability in the Canadian inland seas (i.e., the collective of Hudson Bay, James Bay, and Foxe Basin is identified based on Gravity Recovery and Climate Experiment (GRACE retrievals, a tide-gauge record, and a barotropic model over 2003–2013. This dominant mode of nonseasonal variability is correlated with the North Atlantic Oscillation and is associated with net flows into and out of the Canadian inland seas; the anomalous inflows and outflows, which are reflected in mean sea level and bottom pressure changes, are driven by wind stress anomalies over Hudson Strait, probably related to wind setup, as well as over the northern North Atlantic Ocean, possibly mediated by various wave mechanisms. The mode is also associated with mass redistribution within the Canadian inland seas, reflecting linear response to local wind stress variations under the combined influences of rotation, gravity, and variable bottom topography. Results exemplify the usefulness of GRACE for studying regional ocean circulation and climate.

  4. Standard test method to determine the performance of tiled roofs to wind-driven rain

    Directory of Open Access Journals (Sweden)

    Sánchez de Rojas, M. I.

    2008-09-01

    Full Text Available The extent to which roof coverings can resist water penetration from the combination of wind and rain, commonly referred to as wind driven rain, is important for the design of roofs. A new project of European Standard prEN 15601 (1 specifies a method of test to determine the performance of the roof covering against wind driven rain. The combined action of wind and rain varies considerably with geographical location of a building and the associated differences in the rain and wind climate. Three windrain conditions and one deluge condition covering Northern Europe Coastal, Central Europe and Southern Europe are specified in the project standard, each subdivided into four wind-speeds and rainfall rates to be applied to the test. The project does not contain information on the level of acceptable performance.Para el diseño de los tejados es importante determinar el punto hasta el cual éstos pueden resistirse a la penetración de agua causada por la combinación de viento y lluvia. Un nuevo proyecto de Norma Europeo prEN 15601 (1 especifica un método de ensayo para determinar el comportamiento del tejado frente a la combinación de viento y lluvia. La acción combinada de viento y lluvia varía considerablemente con la situación geográfica de un edificio y las diferencias asociadas al clima de la lluvia y del viento. El proyecto de norma especifica las condiciones de viento y lluvia y una condición de diluvio para cada una de las tres zonas de Europa: Europa del Norte y Costera, Europa Central y Europa del Sur, cada una subdividida en cuatro condiciones de velocidades de viento y caudal de lluvia para ser aplicadas en los ensayos. El proyecto no contiene la información sobre condiciones aceptables.

  5. Simulation of an offshore wind farm using fluid power for centralized electricity generation

    Directory of Open Access Journals (Sweden)

    A. Jarquin Laguna

    2017-07-01

    Full Text Available A centralized approach for electricity generation within a wind farm is explored through the use of fluid power technology. This concept considers a new way of generation, collection and transmission of wind energy inside a wind farm, in which electrical conversion does not occur during any intermediate conversion step before the energy has reached the offshore central platform. A numerical model was developed to capture the relevant physics from the dynamic interaction between different turbines coupled to a common hydraulic network and controller. This paper presents a few examples of the time domain simulation results for a hypothetical hydraulic wind farm subject to turbulent wind conditions. The performance and operational parameters of individual turbines are compared with those of a reference wind farm based on conventional wind turbine generator technology using the same wind farm layout and environmental conditions. For the presented case studies, results indicate that the individual wind turbines are able to operate within operational limits. Despite the stochastic turbulent wind conditions and wake effects, the hydraulic wind farm is able to produce electricity with reasonable performance in both below and above rated conditions. With the current pressure control concept, a continuous operation of the hydraulic wind farm is shown including the full stop of one or more turbines.

  6. Wind power feed-in impact on electricity prices in Germany 2009-2013

    Directory of Open Access Journals (Sweden)

    François Benhmad

    2016-07-01

    Full Text Available Until quite recently no electricity system had faced the challenges associated with high penetrations of renewable energy sources (RES. In this paper, we carry out an empirical analysis for Germany, as a country with high penetration of wind energy, to investigate the well-known merit-order effect. Our main empirical findings suggest that the increasing share of wind power in-feed induces a decrease of electricity spot price level but an increase of spot prices volatility. Furthermore, the relationship between wind power and spot electricity prices can be strongly impacted by European electricity grids interconnection which behaves like a safety valve lowering volatility and limiting the price decrease. Therefore, the impacts of wind generated electricity on electricity spot markets are less clearly pronounced in interconnected systems.

  7. Two-component magnetohydrodynamical outflows around young stellar objects Interplay between stellar magnetospheric winds and disc-driven jets

    National Research Council Canada - National Science Library

    Meliani, Z; Casse, F; Sauty, C

    2006-01-01

    We present the first-ever simulations of non-ideal magnetohydrodynamical (MHD) stellar magnetospheric winds coupled with disc-driven jets where the resistive and viscous accretion disc is self-consistently described...

  8. Wind power deployment in the Swedish-Norwegian tradable electricity certificate market

    OpenAIRE

    Sand, Thea; Stubsjøen, Erik Stavne

    2015-01-01

    This thesis examines the market-based common Swedish-Norwegian tradable electricity certificate support scheme for investments in new electricity generating capacity from renewable energy sources, with a particular focus on deployment of wind power in Norway. We evaluate the costs of onshore wind power projects in the pipeline and their potential to contribute to the quantitative target of adding new renewable electricity generation corresponding to 26.4 TWh per year by 2020. W...

  9. Research for Electric Brake Using NTC Thermistors on Micro Wind Turbine

    OpenAIRE

    Sugawara, Akira; Yamamoto, Kenichi; Yoshimi, Takeshi; Sato, Shingo; Tsurumaki, Akira; Ito, Tsuguru

    2006-01-01

    As a brake system for small wind turbine, mechanical brake and electric brake by the short circuit of 3-phase permanent magnet generator are used. However, an electric braking method may damage the rotor and/or blades by rapid stop of the generator revolution. Moreover, generator winding may also be damaged by large short-circuit current. In this paper, the electric braking method using NTC thermistors (negative temperature coefficient resistors) is proposed as a braking system for a cheaper ...

  10. Wind-driven Modulation of Cross-shelf Exchange Driven by Gravitational Relaxation on a Shelf During Winter

    Science.gov (United States)

    Lockhart, Stephen; Seim, Harvey

    2015-04-01

    A field program was conducted during the Winter of 2012 at Long Bay, off the coast of South Carolina, USA. Previous studies have shown that this region has unusually high wintertime productivity. During winter, the water on this shallow shelf (shelf break at approximately 60m depth) is often well-mixed, characterized by nearly vertical isotherms and a horizontal density gradient. Interestingly, we observed several wintertime stratification events. Integrating data from several sources (gliders, moorings, towed body, weather buoy, satellite), we implemented an energetics analysis to quantify the various physical processes that influence stratification. The analysis shows the importance of the horizontal advection of buoyancy, driven by downwelling favorable winds and Gulf Stream filaments.

  11. Small Wind Electric Systems: A Nebraska Consumer's Guide

    Energy Technology Data Exchange (ETDEWEB)

    2007-12-01

    Small Wind Electric Systems: A Nebraska Consumer's Guide provides consumers with information to help them determine whether a small wind electric system can provide all or a portion of the energy they need for their home or business based on their wind resource, energy needs, and their economics. Topics discussed in the guide include how to make a home more energy efficient, how to choose the correct turbine size, the parts of a wind electric system, how to determine whether enough wind resource exists, how to choose the best site for a turbine, how to connect a system to the utility grid, and whether it's possible to become independent of the utility grid using wind energy. In addition, the cover of the guide contains a list of contacts for more information.

  12. Small Wind Electric Systems: A Colorado Consumer's Guide

    Energy Technology Data Exchange (ETDEWEB)

    2006-12-01

    Small Wind Electric Systems: A Colorado Consumer's Guide provides consumers with information to help them determine whether a small wind electric system can provide all or a portion of the energy they need for their home or business based on their wind resource, energy needs, and economics. Topics include how to make a home more energy efficient, how to choose the correct turbine size, the parts of a wind electric system, how to determine whether enough wind resource exists, how to choose the best site for a turbine, how to connect a system to the utility grid, and whether it's possible to become independent of the utility grid using wind energy. In addition, the cover of the guide contains a list of contacts for more information.

  13. Small Wind Electric Systems: A U.S. Consumer's Guide

    Energy Technology Data Exchange (ETDEWEB)

    2007-08-01

    Small Wind Electric Systems: A U.S. Consumer's Guide provides consumers with information to help them determine whether a small wind electric system can provide all or a portion of the energy they need for their home or business based on their wind resource, energy needs, and their economics. Topics discussed in the guide include how to make a home more energy efficient, how to choose the correct turbine size, the parts of a wind electric system, how to determine whether enough wind resource exists, how to choose the best site for a turbine, how to connect a system to the utility grid, and whether it's possible to become independent of the utility grid using wind energy. In addition, the cover of the guide contains a list of contacts for more information.

  14. Small Wind Electric Systems: An Alaska Consumer's Guide

    Energy Technology Data Exchange (ETDEWEB)

    2007-04-01

    Small Wind Electric Systems: An Alaska Consumer's Guide provides consumers with information to help them determine whether a small wind electric system can provide all or a portion of the energy they need for their home or business based on their wind resource, energy needs, and economics. Topics include how to make a home more energy efficient, how to choose the correct turbine size, the parts of a wind electric system, how to determine whether enough wind resource exists, how to choose the best site for a turbine, how to connect a system to the utility grid, and whether it's possible to become independent of the utility grid using wind energy. In addition, the cover of the guide contains a list of contacts for more information.

  15. Small Wind Electric Systems: A Montana Consumer's Guide (Revised)

    Energy Technology Data Exchange (ETDEWEB)

    2006-04-01

    Small Wind Electric Systems: A Montana Consumer's Guide provides consumers with information to help them determine whether a small wind electric system can provide all or a portion of the energy they need for their home or business based on their wind resource, energy needs, and economics. Topics include how to make a home more energy efficient, how to choose the correct turbine size, the parts of a wind electric system, how to determine whether enough wind resource exists, how to choose the best site for a turbine, how to connect a system to the utility grid, and whether it's possible to become independent of the utility grid using wind energy. In addition, the cover of the guide contains a list of contacts for more information.

  16. Small Wind Electric Systems: An Oregon Consumer's Guide

    Energy Technology Data Exchange (ETDEWEB)

    2007-08-01

    Small Wind Electric Systems: An Oregon Consumer's Guide provides consumers with information to help them determine whether a small wind electric system can provide all or a portion of the energy they need for their home or business based on their wind resource, energy needs, and economics. Topics include how to make a home more energy efficient, how to choose the correct turbine size, the parts of a wind electric system, how to determine whether enough wind resource exists, how to choose the best site for a turbine, how to connect a system to the utility grid, and whether it's possible to become independent of the utility grid using wind energy. In addition, the cover of the guide contains a list of contacts for more information.

  17. Small Wind Electric Systems: An Illinois Consumer's Guide

    Energy Technology Data Exchange (ETDEWEB)

    2007-04-01

    Small Wind Electric Systems: An Illinois Consumer's Guide provides consumers with information to help them determine whether a small wind electric system can provide all or a portion of the energy they need for their home or business based on their wind resource, energy needs, and economics. Topics include how to make a home more energy efficient, how to choose the correct turbine size, the parts of a wind electric system, how to determine whether enough wind resource exists, how to choose the best site for a turbine, how to connect a system to the utility grid, and whether it's possible to become independent of the utility grid using wind energy. In addition, the cover of the guide contains a list of contacts for more information.

  18. Small Wind Electric Systems: A Minnesota Consumer's Guide

    Energy Technology Data Exchange (ETDEWEB)

    2007-04-01

    Small Wind Electric Systems: A Minnesota Consumer's Guide provides consumers with information to help them determine whether a small wind electric system can provide all or a portion of the energy they need for their home or business based on their wind resource, energy needs, and economics. Topics include how to make a home more energy efficient, how to choose the correct turbine size, the parts of a wind electric system, how to determine whether enough wind resource exists, how to choose the best site for a turbine, how to connect a system to the utility grid, and whether it's possible to become independent of the utility grid using wind energy. In addition, the cover of the guide contains a list of contacts for more information.

  19. Small Wind Electric Systems: An Oklahoma Consumer's Guide

    Energy Technology Data Exchange (ETDEWEB)

    2007-08-01

    Small Wind Electric Systems: An Oklahoma Consumer's Guide provides consumers with information to help them determine whether a small wind electric system can provide all or a portion of the energy they need for their home or business based on their wind resource, energy needs, and economics. Topics include how to make a home more energy efficient, how to choose the correct turbine size, the parts of a wind electric system, how to determine whether enough wind resource exists, how to choose the best site for a turbine, how to connect a system to the utility grid, and whether it's possible to become independent of the utility grid using wind energy. In addition, the cover of the guide contains a list of contacts for more information.

  20. Small Wind Electric Systems: A Kansas Consumer's Guide

    Energy Technology Data Exchange (ETDEWEB)

    2007-08-01

    Small Wind Electric Systems: A Kansas Consumer's Guide provides consumers with information to help them determine whether a small wind electric system can provide all or a portion of the energy they need for their home or business based on their wind resource, energy needs, and their economics. Topics discussed in the guide include how to make a home more energy efficient, how to choose the correct turbine size, the parts of a wind electric system, how to determine whether enough wind resource exists, how to choose the best site for a turbine, how to connect a system to the utility grid, and whether it's possible to become independent of the utility grid using wind energy. In addition, the cover of the guide contains a list of contacts for more information.

  1. Small Wind Electric Systems: A Utah Consumer's Guide

    Energy Technology Data Exchange (ETDEWEB)

    2007-08-01

    Small Wind Electric Systems: A Utah Consumer's Guide provides Utah consumers with information to help them determine whether a small wind electric system can provide all or a portion of the energy they need for their home or business based on their wind resource, energy needs, and their economics. Topics discussed in the guide include how to make a home more energy efficient, how to choose the correct turbine size, the parts of a wind electric system, how to determine whether enough wind resource exists, how to choose the best site for a turbine, how to connect a system to the utility grid, and whether it's possible to become independent of the utility grid using wind energy. In addition, the cover of the guide contains a list of contacts for more information.

  2. Small Wind Electric Systems: A Vermont Consumer's Guide

    Energy Technology Data Exchange (ETDEWEB)

    2007-04-01

    Small Wind Electric Systems: A Vermont Consumer's Guide provides consumers with information to help them determine whether a small wind electric system can provide all or a portion of the energy they need for their home or business based on their wind resource, energy needs, and economics. Topics include how to make a home more energy efficient, how to choose the correct turbine size, the parts of a wind electric system, how to determine whether enough wind resource exists, how to choose the best site for a turbine, how to connect a system to the utility grid, and whether it's possible to become independent of the utility grid using wind energy. In addition, the cover of the guide contains a list of contacts for more information.

  3. Small Wind Electric Systems: An Ohio Consumer's Guide

    Energy Technology Data Exchange (ETDEWEB)

    2007-08-01

    Small Wind Electric Systems: An Ohio Consumer's Guide provides consumers with information to help them determine whether a small wind electric system can provide all or a portion of the energy they need for their home or business based on their wind resource, energy needs, and their economics. Topics discussed in the guide include how to make a home more energy efficient, how to choose the correct turbine size, the parts of a wind electric system, how to determine whether enough wind resource exists, how to choose the best site for a turbine, how to connect a system to the utility grid, and whether it's possible to become independent of the utility grid using wind energy. In addition, the cover of the guide contains a list of contacts for more information.

  4. Small Wind Electric Systems: A Washington Consumer's Guide

    Energy Technology Data Exchange (ETDEWEB)

    2007-08-01

    Small Wind Electric Systems: A Washington Consumer's Guide provides consumers with information to help them determine whether a small wind electric system can provide all or a portion of the energy they need for their home or business based on their wind resource, energy needs, and economics. Topics include how to make a home more energy efficient, how to choose the correct turbine size, the parts of a wind electric system, how to determine whether enough wind resource exists, how to choose the best site for a turbine, how to connect a system to the utility grid, and whether it's possible to become independent of the utility grid using wind energy. In addition, the cover of the guide contains a list of contacts for more information.

  5. Small Wind Electric Systems: A Maine Consumer's Guide

    Energy Technology Data Exchange (ETDEWEB)

    2007-08-01

    Small Wind Electric Systems: A Maine Consumer's Guide provides consumers with information to help them determine whether a small wind electric system can provide all or a portion of the energy they need for their home or business based on their wind resource, energy needs, and their economics. Topics discussed in the guide include how to make a home more energy efficient, how to choose the correct turbine size, the parts of a wind electric system, how to determine whether enough wind resource exists, how to choose the best site for a turbine, how to connect a system to the utility grid, and whether it's possible to become independent of the utility grid using wind energy. In addition, the cover of the guide contains a list of contacts for more information.

  6. Small Wind Electric Systems: A Hawaii Consumer's Guide

    Energy Technology Data Exchange (ETDEWEB)

    2007-08-01

    Small Wind Electric Systems: A Hawaii Consumer's Guide provides consumers with information to help them determine whether a small wind electric system can provide all or a portion of the energy they need for their home or business based on their wind resource, energy needs, and their economics. Topics discussed in the guide include how to make a home more energy efficient, how to choose the correct turbine size, the parts of a wind electric system, how to determine whether enough wind resource exists, how to choose the best site for a turbine, how to connect a system to the utility grid, and whether it's possible to become independent of the utility grid using wind energy. In addition, the cover of the guide contains a list of contacts for more information.

  7. Small Wind Electric Systems: A South Dakota Consumer's Guide

    Energy Technology Data Exchange (ETDEWEB)

    2007-04-01

    Small Wind Electric Systems: A South Dakota Consumer's Guide provides consumers with information to help them determine whether a small wind electric system can provide all or a portion of the energy they need for their home or business based on their wind resource, energy needs, and economics. Topics include how to make a home more energy efficient, how to choose the correct turbine size, the parts of a wind electric system, how to determine whether enough wind resource exists, how to choose the best site for a turbine, how to connect a system to the utility grid, and whether it's possible to become independent of the utility grid using wind energy. In addition, the cover of the guide contains a list of contacts for more information.

  8. Small Wind Electric Systems: A North Dakota Consumer's Guide

    Energy Technology Data Exchange (ETDEWEB)

    2007-04-01

    Small Wind Electric Systems: A North Dakota Consumer's Guide provides consumers with information to help them determine whether a small wind electric system can provide all or a portion of the energy they need for their home or business based on their wind resource, energy needs, and economics. Topics include how to make a home more energy efficient, how to choose the correct turbine size, the parts of a wind electric system, how to determine whether enough wind resource exists, how to choose the best site for a turbine, how to connect a system to the utility grid, and whether it's possible to become independent of the utility grid using wind energy. In addition, the cover of the guide contains a list of contacts for more information.

  9. Small Wind Electric Systems: A Virginia Consumer's Guide

    Energy Technology Data Exchange (ETDEWEB)

    2007-01-01

    Small Wind Electric Systems: A Virginia Consumer's Guide provides consumers with information to help them determine whether a small wind electric system can provide all or a portion of the energy they need for their home or business based on their wind resource, energy needs, and economics. Topics include how to make a home more energy efficient, how to choose the correct turbine size, the parts of a wind electric system, how to determine whether enough wind resource exists, how to choose the best site for a turbine, how to connect a system to the utility grid, and whether it's possible to become independent of the utility grid using wind energy. In addition, the cover of the guide contains a list of contacts for more information.

  10. Small Wind Electric Systems: A Pennsylvania Consumer's Guide

    Energy Technology Data Exchange (ETDEWEB)

    2007-08-01

    Small Wind Electric Systems: A Pennsylvania Consumer's Guide provides consumers with information to help them determine whether a small wind electric system can provide all or a portion of the energy they need for their home or business based on their wind resource, energy needs, and their economics. Topics discussed in the guide include how to make a home more energy efficient, how to choose the correct turbine size, the parts of a wind electric system, how to determine whether enough wind resource exists, how to choose the best site for a turbine, how to connect a system to the utility grid, and whether it's possible to become independent of the utility grid using wind energy. In addition, the cover of the guide contains a list of contacts for more information.

  11. Small Wind Electric Systems: A Montana Consumer's Guide

    Energy Technology Data Exchange (ETDEWEB)

    2007-08-01

    Small Wind Electric Systems: A Montana Consumer's Guide provides consumers with information to help them determine whether a small wind electric system can provide all or a portion of the energy they need for their home or business based on their wind resource, energy needs, and economics. Topics include how to make a home more energy efficient, how to choose the correct turbine size, the parts of a wind electric system, how to determine whether enough wind resource exists, how to choose the best site for a turbine, how to connect a system to the utility grid, and whether it's possible to become independent of the utility grid using wind energy. In addition, the cover of the guide contains a list of contacts for more information.

  12. Small Wind Electric Systems: A Hawaii Consumer's Guide

    Energy Technology Data Exchange (ETDEWEB)

    2005-03-01

    Small Wind Electric Systems: A Hawaii Consumer's Guide provides consumers with information to help them determine whether a small wind electric system can provide all or a portion of the energy they need for their home or business based on their wind resource, energy needs, and their economics. Topics discussed in the guide include how to make a home more energy efficient, how to choose the correct turbine size, the parts of a wind electric system, how to determine whether enough wind resource exists, how to choose the best site for a turbine, how to connect a system to the utility grid, and whether it's possible to become independent of the utility grid using wind energy. In addition, the cover of the guide contains a list of contacts for more information.

  13. Small Wind Electric Systems: A Missouri Consumer's Guide

    Energy Technology Data Exchange (ETDEWEB)

    2005-03-01

    Small Wind Electric Systems: A Missouri Consumer's Guide provides consumers with information to help them determine whether a small wind electric system can provide all or a portion of the energy they need for their home or business based on their wind resource, energy needs, and their economics. Topics discussed in the guide include how to make a home more energy efficient, how to choose the correct turbine size, the parts of a wind electric system, how to determine whether enough wind resource exists, how to choose the best site for a turbine, how to connect a system to the utility grid, and whether it's possible to become independent of the utility grid using wind energy. In addition, the cover of the guide contains a list of contacts for more information.

  14. Small Wind Electric Systems: An Indiana Consumer's Guide

    Energy Technology Data Exchange (ETDEWEB)

    2005-03-01

    Small Wind Electric Systems: An Indiana Consumer's Guide provides consumers with information to help them determine whether a small wind electric system can provide all or a portion of the energy they need for their home or business based on their wind resource, energy needs, and their economics. Topics discussed in the guide include how to make a home more energy efficient, how to choose the correct turbine size, the parts of a wind electric system, how to determine whether enough wind resource exists, how to choose the best site for a turbine, how to connect a system to the utility grid, and whether it's possible to become independent of the utility grid using wind energy. In addition, the cover of the guide contains a list of contacts for more information.

  15. Wind Energy Based Electric Vehicle Charging Stations Sitting. A GIS/Wind Resource Assessment Approach

    Directory of Open Access Journals (Sweden)

    George Xydis

    2015-11-01

    Full Text Available The transportation sector is severely correlated with major problems in environment, citizens’ health, climate and economy. Issues such as traffic, fuel cost and parking space have make life more difficult, especially in the dense urban environment. Thus, there is a great need for the development of the electric vehicle (EV sector. The number of cars in cities has increased so much that the current transportation system (roads, parking places, traffic lights, etc. cannot accommodate them properly. The increasing number of vehicles does not affect only humans but also the environment, through air and noise pollution. According to EPA, the 39.2% of total gas emissions in 2007 was caused by transportation activities. Studies have shown that the pollutants are not only gathered in the major roads and/or highways but can travel depending on the meteorological conditions leading to generic pollution. The promotion of EVs and the charging stations are both equally required to be further developed in order EVs to move out of the cities and finally confront the range problem. In this work, a wind resource and a GIS analysis optimizes in a wider area the sitting of wind based charging stations and proposes an optimizing methodology.

  16. Surface melt on Antarctic ice shelves driven by wind-albedo interactions

    Science.gov (United States)

    Lhermitte, Stef; Lenaerts, Jan

    2017-04-01

    Surface melt and subsequent firn air depletion is considered an important precursor for disintegration of Antarctic ice shelves, causing grounded glaciers to accelerate and sea level to rise. Recent studies have highlighted the impact of surface winds on Antarctic ice shelf melt, both on the Antarctic Peninsula and in East Antarctica. In the Antarctic Peninsula, foehn winds enhance melting near the grounding line, which in the recent past has led to the disintegration of the most northerly ice shelves. On the East Antarctic ice shelves, on the other hand, meltwater-induced firn air depletion is found in the grounding zone as result of persistent katabatic winds, regionally warming the atmosphere and inducing a melt-albedo feedback. Here, we use a combination multi-source satellite imagery, snow modelling, climate model output and in-situ observations to highlight the importance of this wind-induced melt and to show its widespread occurrence across Antarctica. The satellite imagery gives insight in the meltwater drainage systems, showing spatio-temporal changes in both supraglacial and englacial water throughout the melt season and during the subsequent winter. Although the wind-induced melt is a regional phenomenon with strong inter-annual variability, it is strongly correlated to larger scale climate parameters, such as summer surface temperature. Based on these correlations and snow model output driven by future climate scenarios, we can constrain the future changes to this local melt near the grounding line.

  17. Modelling the potential for wind energy integration on China’s coal-heavy electricity grid

    Science.gov (United States)

    Davidson, Michael R.; Zhang, Da; Xiong, Weiming; Zhang, Xiliang; Karplus, Valerie J.

    2016-07-01

    Expanding the use of wind energy for electricity generation forms an integral part of China’s efforts to address degraded air quality and climate change. However, the integration of wind energy into China’s coal-heavy electricity system presents significant challenges owing to wind’s variability and the grid’s system-wide inflexibilities. Here we develop a model to predict how much wind energy can be generated and integrated into China’s electricity mix, and estimate a potential production of 2.6 petawatt-hours (PWh) per year in 2030. Although this represents 26% of total projected electricity demand, it is only 10% of the total estimated physical potential of wind resources in the country. Increasing the operational flexibility of China’s coal fleet would allow wind to deliver nearly three-quarters of China’s target of producing 20% of primary energy from non-fossil sources by 2030.

  18. Non-volatile electrically-driven repeatable magnetization reversal with no applied magnetic field

    National Research Council Canada - National Science Library

    Ghidini, M; Pellicelli, R; Prieto, J L; Moya, X; Soussi, J; Briscoe, J; Dunn, S; Mathur, N D

    2013-01-01

    ...)-based dielectric layers. In an electrode exposed by polishing approximately normal to the layers, we find a perpendicularly magnetized feature that exhibits non-volatile electrically driven repeatable magnetization reversal...

  19. Line-driven disc wind model for ultrafast outflows in active galactic nuclei - scaling with luminosity

    Science.gov (United States)

    Nomura, M.; Ohsuga, K.

    2017-03-01

    In order to reveal the origin of the ultrafast outflows (UFOs) that are frequently observed in active galactic nuclei (AGNs), we perform two-dimensional radiation hydrodynamics simulations of the line-driven disc winds, which are accelerated by the radiation force due to the spectral lines. The line-driven winds are successfully launched for the range of MBH = 106-9 M⊙ and ε = 0.1-0.5, and the resulting mass outflow rate (dot{M_w}), momentum flux (dot{p_w}), and kinetic luminosity (dot{E_w}) are in the region containing 90 per cent of the posterior probability distribution in the dot{M}_w-Lbol plane, dot{p}_w-Lbol plane, and dot{E}_w-Lbol plane shown in Gofford et al., where MBH is the black hole mass, ε is the Eddington ratio, and Lbol is the bolometric luminosity. The best-fitting relations in Gofford et al., d log dot{M_w}/d log {L_bol}˜ 0.9, d log dot{p_w}/d log {L_bol}˜ 1.2, and d log dot{E_w}/d log {L_bol}˜ 1.5, are roughly consistent with our results, d log dot{M_w}/d log {L_bol}˜ 9/8, d log dot{p_w}/d log {L_bol}˜ 10/8, and d log dot{E_w}/d log {L_bol}˜ 11/8. In addition, our model predicts that no UFO features are detected for the AGNs with ε ≲ 0.01, since the winds do not appear. Also, only AGNs with MBH ≲ 108 M⊙ exhibit the UFOs when ε ∼ 0.025. These predictions nicely agree with the X-ray observations. These results support that the line-driven disc wind is the origin of the UFOs.

  20. Variable Nature of Magnetically-Driven X-Ray Disk-Winds in XRB/AGNs

    Science.gov (United States)

    Fukumura, Keigo; Kazanas, Demosthenes; Behar, Ehud; Tombesi, Francesco; shrader, Chris

    2018-01-01

    With an increasing number of high-S/N spectroscopic data available, it is being speculated that certain types of ionized winds detected in X-ray may be exhibiting characteristic correlations among (1) X-ray spectral state, (2) ionizing luminosity and (3) absorber's property. For example, in the case of luminous quasars such as PDS456, ionizing X-ray luminosity may be correlated to the wind kinematics (i.e. line-of-sight velocity) as expected from radiative-driven scenario. On the other hand, in the case of black hole XRBs such as GRS1915+105, harder SED during the so called low/hard state is thought to turn off X-ray winds. While these are phenomena across different mass-scale, one might argue that the reported correlations may be related to the intense radiation field. In this presentation, we discuss, based on the ideal MHD framework, that these interesting trends suggested in X-ray analyses may well be reconciled self-consistently with magnetic origin as well. In this view, ionized winds are intrinsically always present magnetically launched from the disk, while its large-scale ionization structure will respond to various physical changes due mainly to the underlying radiation field (i.e. hardness and/or luminosity) and wind structure (i.e. density gradient). The primary aim of the current theoretical study is to better understand a potential coupling between wind's condition and ionizing luminosity/spectral state by fully exploiting the recent MHD wind models that we are proposing, which can allow us to further identify the fundamental launching process. We show, as a preliminary work, a unique predictable signature of absorption spectra calculated from the model to probe expected correlations.

  1. Generation Ratio Availability Assessment of Electrical Systems for Offshore Wind Farms

    DEFF Research Database (Denmark)

    Zhao, Menghua; Chen, Zhe; Blaabjerg, Frede

    2007-01-01

    An availability index, Generation Ratio Availability (GRA), is proposed to evaluate the electrical system of offshore wind farms (OWF). The GRA is the probability that at least a certain percent of wind power could be transferred to the grid system through the concerned electrical system. The GRA....... Comprehensive studies have been conducted to investigate the influence of the network design, component parameters, and wind-speed regimes on the GRA. The analysis presented in this paper is useful for both future wind farm planning and existing OWF evaluation....

  2. Comparison of Transformer Winding Methods for Contactless Power Transfer Systems of Electric Vehicle

    Science.gov (United States)

    Kaneko, Yasuyoshi; Ehara, Natsuki; Iwata, Takuya; Abe, Shigeru; Yasuda, Tomio; Ida, Kazuhiko

    This paper describes the comparison of the characteristics of double- and single-sided windings of contactless power transfer systems used in electric vehicles. The self-inductance changes with the electric current when the gap length is fixed in single-sided windings. The issue is resolved by maintaining the secondary voltage constant. In the case of double-sided windings, the transformer can be miniaturized in comparison with the single-sided winding transformer. However, the coupling factor is small, and appropriate countermeasures must be adopted to reduce the back leakage flux. The leakage flux is reduced by placing an aluminum board behind the transformer. Thus, the coupling factor increases.

  3. Estimated performance of solar PV and wind turbine systems compared to coincident electrical demand in Minnesota

    Energy Technology Data Exchange (ETDEWEB)

    Artig, R. [Minnesota Dept. of Public Service, St. Paul, MN (United States)

    1995-10-01

    The Minnesota Department of Public Service (department), with the cooperation of Northern States Power (NSP) and US Department of Energy, is making a detailed study of wind and solar resources in the Buffalo Ridge area of southwestern Minnesota. The purpose of the study is to determine the viability of using a combination of wind and solar generation facilities to help meet electrical demand in the region. Through the Solar/Wind Study, five monitoring sites have been established to collect solar radiation and temperature data as well as to record wind speed and direction information at multiple elevations. In this paper, the data from the first year of the Solar/Wind Study are used to directly compare the projected hourly production of electricity from the wind and solar resources to hourly electrical demand. This study compares the potential electrical production from these renewable resources concurrent with peak or near peak occurrences in electrical demand. The electrical demand information used in this study is from two utilities: NSP, a utility that supplies electricity to a combination of urban residential, commercial, and industrial customers; and Cooperative Power (CP), which provides power primarily to suburban and rural residential customers. Estimates of the performance of solar PV systems were made using PVFORM, a simulation program from Sandia National Laboratories. Analysis of first year data indicates that the availability of electricity generated from a combination of solar and wind resources matches period of high peak demand for Northern States Power. The value of adding wind and solar generated electricity to the utility`s resource mix merits further investigation. The match between solar and wind power availability and Cooperative Power`s peak demand period is not apparent, but here, too, further study is needed.

  4. Determination of recoverable wind energy for electricity generation ...

    African Journals Online (AJOL)

    Utilization of renewable energy source, essentially the wind energy, has been growing rapidly in the whole world due to environmental pollution, consumption of the limited fossil fuels and global warming. Moreover, wind resource determination is a fundamental step in planning a wind energy project and exhaustive ...

  5. Evaluation of a wind turbine electric power generator

    Science.gov (United States)

    Swim, W. B.

    1981-01-01

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

  6. Integrating Wind Power in Electricity Grids : an Economic Analysis

    NARCIS (Netherlands)

    Liu, J.; Kooten, van G.C.; Pitt, L.

    2005-01-01

    As a renewable energy source, wind power is gaining popularity as a favoured alternative to fossil fuel, nuclear and hydro power generation. In Europe, countries are required to achieve 15% of their energy consumption from wind by 2010 as the EU strives to meet its Kyoto obligations. Wind power is

  7. Electric field driven switching of individual magnetic skyrmions

    OpenAIRE

    Hsu, Pin-Jui; Kubetzka, André; Finco, Aurore; Romming, Niklas; von Bergmann, Kirsten; Wiesendanger, Roland

    2016-01-01

    Controlling magnetism with electric fields is a key challenge to develop future energy-efficient devices, however, the switching between inversion symmetric states, e.g. magnetization up and down as used in current technology, is not straightforward, since the electric field does not break time-reversal symmetry. Here, we demonstrate that local electric fields can be used to reversibly switch between a magnetic skyrmion and the ferromagnetic state. These two states are topologically inequival...

  8. Implementation of cable models for studies of compatibility of electric components in wind farms

    DEFF Research Database (Denmark)

    Holdyk, Andrzej; Holbøll, Joachim; Jensen, Asger

    2011-01-01

    Study of interactions between electric components in power systems is getting more important in the view of an increasing degree of systems’ complexity and, as in the case of wind farms, risk of systematic (highly repeatable) design problems. So far there have not been many studies treating...... that problem in a sufficiently general way, trying to take into consideration different layouts of farms and different wind farm electric environments at the same time. This paper introduces a first step towards the concept of compatibility of electric components in wind farms by relating different cable...

  9. Use of Three-Level Power Converters in Wind-Driven Permanent-Magnet Synchronous Generators with Unbalanced Loads

    Directory of Open Access Journals (Sweden)

    Ming-Hung Chen

    2015-06-01

    Full Text Available This paper describes the design and implementation of three-level power converters for wind-driven permanent-magnet synchronous generators with unbalanced loads. To increase voltage stress and reduce current harmonics in the electrical power generated by a wind generator, a three-phase, three-level rectifier is used. Because a synchronous rotating frame is used on the AC-input side, the use of a neutral-point-clamped controller is proposed to increase the power factor to unity and reduce current harmonics. Furthermore, a novel six-leg inverter is proposed for transferring energy from the DC voltage to a three-phase, four-wire AC source with a constant voltage and a constant frequency. The power converters also contain output transformers and filters for power buffering and filtering, respectively. All three output phase voltages are fed back to control the inverter output during load variations. A digital signal processor is used as the core control device for implementing a 1.5 kV, 75 kW drive system. Experimental data show that the power factor is successfully increased to unity and the total current harmonic distortion is 3.2% on the AC-input side. The entire system can attain an efficiency of 91%, and the voltage error between the upper and lower capacitors is approximately zero. Experimental results that confirm the high performance of the proposed system are presented.

  10. Electric utility application of wind energy conversion systems on the island of Oahu

    Energy Technology Data Exchange (ETDEWEB)

    Lindley, C.A.; Melton, W.C.

    1979-02-23

    This wind energy application study was performed by The Aerospace Corporation for the Wind Systems Branch of the Department of Energy. The objective was to identify integration problems for a Wind Energy Conversion System (WECS) placed into an existing conventional utility system. The integration problems included environmental, institutional and technical aspects as well as economic matters, but the emphasis was on the economics of wind energy. The Hawaiian Electric Company utility system on the island of Oahu was selected for the study because of the very real potential for wind energy on that island, and because of the simplicity afforded in analyzing that isolated utility.

  11. The Darrieus wind turbine for electrical power generation

    Science.gov (United States)

    Robinson, M. L.

    1981-06-01

    Aspects of wind as an energy source and the momentum theory of wind turbines are briefly examined. Types of Darrieus wind turbine are described; attention is given to a turbine with airfoil blades curved in troposkein form, and a turbine with straight blades of fixed or variable pitch. The Darrieus vertical-axis wind turbine is then considered with regard to aerodynamics, annual energy output, structures, control systems, and energy storage. Brief reviews of selected Darrieus wind turbine projects are given, including those at Magdalen Islands, Canada, Sandia Laboratories, Reading University, and Australia and New Zealand.

  12. Simulation of an offshore wind farm using fluid power for centralized electricity generation

    Science.gov (United States)

    Jarquin-Laguna, A.

    2016-09-01

    A centralized approach for electricity generation within a wind farm is explored through the use of fluid power technology. This concept considers a new way of generation, collection and transmission of wind energy inside a wind farm, in which electrical conversion does not occur during any intermediate conversion step before the energy has reached the offshore central platform. A numerical model was developed to capture the relevant physics from the dynamic interaction between different turbines coupled to a common hydraulic network and controller. This paper presents two examples of the time-domain simulation results for an hypothetical hydraulic wind farm subject to turbulent wind conditions. The performance and operational parameters of individual turbines are compared with those of a reference wind farm with conventional technology turbines, using the same wind farm layout and environmental conditions. For the presented case study, results indicate that the individual wind turbines are able to operate within operational limits with the current pressure control concept. Despite the stochastic turbulent wind input and wake effects, the hydraulic wind farm is able to produce electricity with reasonable performance in both below and above rated conditions.

  13. Electric-field-driven switching of individual magnetic skyrmions.

    Science.gov (United States)

    Hsu, Pin-Jui; Kubetzka, André; Finco, Aurore; Romming, Niklas; von Bergmann, Kirsten; Wiesendanger, Roland

    2017-02-01

    Controlling magnetism with electric fields is a key challenge to develop future energy-efficient devices. The present magnetic information technology is mainly based on writing processes requiring either local magnetic fields or spin torques, but it has also been demonstrated that magnetic properties can be altered on the application of electric fields. This has been ascribed to changes in magnetocrystalline anisotropy caused by spin-dependent screening and modifications of the band structure, changes in atom positions or differences in hybridization with an adjacent oxide layer. However, the switching between states related by time reversal, for example magnetization up and down as used in the present technology, is not straightforward because the electric field does not break time-reversal symmetry. Several workarounds have been applied to toggle between bistable magnetic states with electric fields, including changes of material composition as a result of electric fields. Here we demonstrate that local electric fields can be used to switch reversibly between a magnetic skyrmion and the ferromagnetic state. These two states are topologically inequivalent, and we find that the direction of the electric field directly determines the final state. This observation establishes the possibility to combine electric-field writing with the recently envisaged skyrmion racetrack-type memories.

  14. Electric-field-driven switching of individual magnetic skyrmions

    Science.gov (United States)

    Hsu, Pin-Jui; Kubetzka, André; Finco, Aurore; Romming, Niklas; von Bergmann, Kirsten; Wiesendanger, Roland

    2017-02-01

    Controlling magnetism with electric fields is a key challenge to develop future energy-efficient devices. The present magnetic information technology is mainly based on writing processes requiring either local magnetic fields or spin torques, but it has also been demonstrated that magnetic properties can be altered on the application of electric fields. This has been ascribed to changes in magnetocrystalline anisotropy caused by spin-dependent screening and modifications of the band structure, changes in atom positions or differences in hybridization with an adjacent oxide layer. However, the switching between states related by time reversal, for example magnetization up and down as used in the present technology, is not straightforward because the electric field does not break time-reversal symmetry. Several workarounds have been applied to toggle between bistable magnetic states with electric fields, including changes of material composition as a result of electric fields. Here we demonstrate that local electric fields can be used to switch reversibly between a magnetic skyrmion and the ferromagnetic state. These two states are topologically inequivalent, and we find that the direction of the electric field directly determines the final state. This observation establishes the possibility to combine electric-field writing with the recently envisaged skyrmion racetrack-type memories.

  15. Development of a Wind Plant Large-Eddy Simulation with Measurement-Driven Atmospheric Inflow

    Energy Technology Data Exchange (ETDEWEB)

    Quon, Eliot W.; Churchfield, Matthew J.; Cheung, Lawrence; Kern, Stefan

    2017-01-09

    This paper details the development of an aeroelastic wind plant model with large-eddy simulation (LES). The chosen LES solver is the Simulator for Wind Farm Applications (SOWFA) based on the OpenFOAM framework, coupled to NREL's comprehensive aeroelastic analysis tool, FAST. An atmospheric boundary layer (ABL) precursor simulation was constructed based on assessments of meteorological tower, lidar, and radar data over a 3-hour window. This precursor was tuned to the specific atmospheric conditions that occurred both prior to and during the measurement campaign, enabling capture of a night-to-day transition in the turbulent ABL. In the absence of height-varying temperature measurements, spatially averaged radar data were sufficient to characterize the atmospheric stability of the wind plant in terms of the shear profile, and near-ground temperature sensors provided a reasonable estimate of the ground heating rate describing the morning transition. A full aeroelastic simulation was then performed for a subset of turbines within the wind plant, driven by the precursor. Analysis of two turbines within the array, one directly waked by the other, demonstrated good agreement with measured time-averaged loads.

  16. Development of a Wind Plant Large-Eddy Simulation with Measurement-Driven Atmospheric Inflow: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Quon, Eliot; Churchfield, Matthew; Cheung, Lawrence; Kern, Stefan

    2017-02-01

    This paper details the development of an aeroelastic wind plant model with large-eddy simulation (LES). The chosen LES solver is the Simulator for Wind Farm Applications (SOWFA) based on the OpenFOAM framework, coupled to NREL's comprehensive aeroelastic analysis tool, FAST. An atmospheric boundary layer (ABL) precursor simulation was constructed based on assessments of meteorological tower, lidar, and radar data over a 3-hour window. This precursor was tuned to the specific atmospheric conditions that occurred both prior to and during the measurement campaign, enabling capture of a night-to-day transition in the turbulent ABL. In the absence of height-varying temperature measurements, spatially averaged radar data were sufficient to characterize the atmospheric stability of the wind plant in terms of the shear profile, and near-ground temperature sensors provided a reasonable estimate of the ground heating rate describing the morning transition. A full aeroelastic simulation was then performed for a subset of turbines within the wind plant, driven by the precursor. Analysis of two turbines within the array, one directly waked by the other, demonstrated good agreement with measured time-averaged loads.

  17. Fast and slow radiation-driven wind solutions using ZEUS-3D

    Science.gov (United States)

    Araya, I.; Curé, M.; ud-Doula, A.; Santillán, A.

    2014-10-01

    Currently, the theory of radiation-driven winds of massive stars possess three known solutions for the velocity and density profiles of the stellar winds, namely: the fast, Ω -slow and δ -slow solutions. In order to confirm their stability we use a time-dependent numerical hydrodynamic code called ZEUS-3D, and then we compare their results with the stationary solutions from our numerical hydrodynamic code. ZEUS-3D needs an initial trial solution to start to integrate, for this we use the stationary solution (from our code) or a β-law for the velocity field. In both cases we obtain the same results. Fast and both slow stationary solutions are attained in ZEUS-3D and are all stable. Furthermore, there is a very good agreement with the velocity and density fields from ZEUS-3D and our code, having differences between the terminal velocities lower than 3%. In addition, we found that ZEUS-3D is very sensitive to the boundary conditions (base density and velocity profile), in some cases we obtain kinks in the velocity profiles, similar to the ones obtained by Madura et al. (2007) for stars with high rotation. Such kinks are most likely the result of the wind being mass overloaded, but further investigation is needed to understand its nature better. Currently, we are exploring the effects of small perturbation at the base of the wind in order to study possible transitions or oscillations between δ-slow and fast solutions.

  18. Reflection driven wave turbulence in an open field and the structure of solar wind

    Science.gov (United States)

    Asgari-Targhi, M.; van Ballegooijen, A. A.

    2016-12-01

    We present results from an extensive study of an open magnetic field line positioned at the center of a coronal hole. We test the hypothesis that reflection-driven wave turbulence can provide the energy needed for heating the coronal plasma in the acceleration region of the fast solar wind. We use the reduced magnetohydrodynamic simulations to describe the wave turbulence where the simulated wave dissipation rates are compared with those needed to sustain the background atmosphere. We consider the effects of density fluctuations, which may significantly increase the turbulent heating rate. These density variations simulate the effects of compressive MHD waves on the Alfvén waves. We find that such variations significantly enhance the wave reflection and thereby the turbulent dissipation rates, producing enough heat to maintain the background atmosphere. We conclude that interactions between Alfvén and compressive waves may play an important role in the turbulent heating of the fast solar wind.

  19. Optimal Operation of Plug-In Electric Vehicles in Power Systems with High Wind Power Penetrations

    DEFF Research Database (Denmark)

    Hu, Weihao; Su, Chi; Chen, Zhe

    2013-01-01

    in the power systems with high wind power penetrations. In this paper, the integration of plug-in electric vehicles in the power systems with high wind power penetrations is proposed and discussed. Optimal operation strategies of PEV in the spot market are proposed in order to decrease the energy cost for PEV......The Danish power system has a large penetration of wind power. The wind fluctuation causes a high variation in the power generation, which must be balanced by other sources. The battery storage based Plug-In Electric Vehicles (PEV) may be a possible solution to balance the wind power variations...... demand is chosen as the studied case. The results show that an optimal operation of PEV in both spot market and regulation market can not only decrease the energy costs for PEV owners, but also significantly decrease the power deviations between West Denmark and Union for the Coordination of Electricity...

  20. Technologies for production of Electricity and Heat in Sweden. Wind energy in perspective of international development

    DEFF Research Database (Denmark)

    Clausen, Niels-Erik; Lawaetz, Henrik; Lemming, Jørgen Kjærgaard

    with availability on mature markets somewhere around 99%. An important contributor to the growth of the European market for wind energy technology has been EU framework legislation combined with legislation at the national level. The binding target for renewable energy in Sweden is proposed to be 49% of the final...... of wind power create a specific challenges for the future energy systems compared to those of today. The economics of wind power depends mainly of investment cost, operation and maintenance costs, electricity production and turbine lifetime. An average turbine installed in Europe has a total investment......The development of the wind energy technology has been very successful from the 1970’s and up till now. Initially there was a battle between wind turbine concepts, but the commercial winner today is the three-bladed horizontal axis, upwind, electricity producing and grid connected wind turbine...

  1. Origins of wind-driven intraseasonal sea level variations in the North Indian Ocean coastal waveguide

    Digital Repository Service at National Institute of Oceanography (India)

    Suresh, I.; Vialard, J.; Lengaigne, M.; Han, W.; McCreary, J.P.; Durand, F.; Muraleedharan, P.M.

    1. CSIR-National Institute of Oceanography, Goa, India 2. LOCEAN, IRD/CNRS/UPMC/MNHN, Paris, France 3. Dept. Of Atmospheric and Oceanic Sciences, University of Colorado, Boulder, USA 4. IPRC/SOEST, Univ. Hawaii, Hawaii, USA 5. LEGOS, IRD... version: Geophys. Res. Lett., vol.40(21); 2013; 5740-5744 Origins of wind-driven intraseasonal sea level variations in the North Indian Ocean coastal waveguide I. Suresh1, J. Vialard2, M. Lengaigne2, W. Han3, J. McCreary4, F. Durand5, P.M. Muraleedharan1...

  2. Power Electronic Drives, Controls, and Electric Generators for Large Wind Turbines - An Overview

    DEFF Research Database (Denmark)

    Ma, Ke; Tutelea, L.; Boldea, Ion

    2015-01-01

    of power electronics, ranging from devices to circuit topologies, and similar matters for electric generators, together with results of optimal design studies are included. It is shown that the individual power rating of wind turbines has increased over the years, and technologies required to reach......Wind represents a major and growing source of renewable energy for the electric power systems. This article provides an overview of state-of-the-art technologies and anticipated developments in the area of power electronic drives, controls, and electric generators for large multi-megawatt wind...... turbine systems. The principal components employed in a turbine for energy conversion from wind to electricity are described, and the main solutions that are commercially available are briefly reviewed. The specific issues of complex mission profiles, power codes, and reliability are discussed. Topics...

  3. Wind-powered electrical systems : highway rest areas, weigh stations, and team section buildings.

    Science.gov (United States)

    2009-02-01

    This project considered the use of wind for providing electrical power at Illinois Department of Transportation : (IDOT) highway rest areas, weigh stations, and team section buildings. The goal of the project was to determine : the extent to which wi...

  4. 75 FR 27550 - Electrical Interconnection of the Juniper Canyon I Wind Project

    Science.gov (United States)

    2010-05-17

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Bonneville Power Administration Electrical Interconnection of the Juniper Canyon I Wind Project AGENCY: Bonneville Power Administration (BPA), Department of Energy (DOE). ACTION: Notice of Availability of Record...

  5. How to improve the design of the electrical system in future wind power plants

    DEFF Research Database (Denmark)

    Arana Aristi, Iván; Holbøll, Joachim; Bak, C. L.

    2009-01-01

    is to improve the understanding of the main electrical components in wind farms, based on available information, measurement data and simulation tools. The aim of these projects is to obtain validated models of wind turbine (WT) generators, WT converters, WT transformers, submarine cables, circuit breakers...... and wind farm transformers, and to develop a methodology on how to select appropriate equipment for the power system, control system and protection system....

  6. CONTROL OPTIMIZATION OF WIND UNIT WITH HELICOID VERTICALLY AXIAL WINDMILL AND SYNCHRONOUS MAGNETO-ELECTRIC GENERATOR

    Directory of Open Access Journals (Sweden)

    М. М. Оlеshkеvich

    2005-01-01

    Full Text Available The paper considers a helicoid vertically axial windmill geared to synchronous magneto-electric generator which operates for a power system or an independent resistive load. In order to optimize operational modes of a wind power unit a mathematical model and software have been developed and a number of calculative experiments have been carried out. The obtained law of wind unit control makes it possible to ensure maximum power output and stability in a wind unit operation.

  7. Rotary motion driven by a direct current electric field

    OpenAIRE

    Takinoue, Masahiro; Atsumi, Yu; Yoshikawa, Kenichi

    2010-01-01

    We report the rotary motion of an aqueous microdroplet in an oil phase under a stationary direct current electric field. A droplet exhibits rotary motion under a suitable geometrical arrangement of positive and negative electrodes. Rotary motion appears above a certain critical electric potential and its frequency increases with an increase in the potential. A simple theoretical model is proposed to describe the occurrence of this rotary motion, together with an argument for the future expans...

  8. Non-volatile electrically-driven repeatable magnetization reversal with no applied magnetic field.

    Science.gov (United States)

    Ghidini, M; Pellicelli, R; Prieto, J L; Moya, X; Soussi, J; Briscoe, J; Dunn, S; Mathur, N D

    2013-01-01

    Repeatable magnetization reversal under purely electrical control remains the outstanding goal in magnetoelectrics. Here we use magnetic force microscopy to study a commercially manufactured multilayer capacitor that displays strain-mediated coupling between magnetostrictive Ni electrodes and piezoelectric BaTiO(3)-based dielectric layers. In an electrode exposed by polishing approximately normal to the layers, we find a perpendicularly magnetized feature that exhibits non-volatile electrically driven repeatable magnetization reversal with no applied magnetic field. Using micromagnetic modelling, we interpret this nominally full magnetization reversal in terms of a dynamic precession that is triggered by strain from voltage-driven ferroelectric switching that is fast and reversible. The anisotropy field responsible for the perpendicular magnetization is reversed by the electrically driven magnetic switching, which is, therefore, repeatable. Our demonstration of non-volatile magnetic switching via volatile ferroelectric switching may inspire the design of fatigue-free devices for electric-write magnetic-read data storage.

  9. User-driven Points for Feedback Motivated Electricity savings in Private Households

    DEFF Research Database (Denmark)

    Kanstrup, Anne Marie; Christiansen, Ellen Tove

    This paper reports from a study of design and exploration of feedback for motivated electricity consumption to private households based on user-driven innovation. Traditionally feedback is designed on the basis of technical possibilities and/or theories on consumer behavior. In this study we...... present i) methods for engaging consumers in design of feedback by use of methods and techniques for evoking users innovative potential and ii) results from a user-driven process in form of design concepts and design examples for a home devise for feedback on electricity consumption. The paper starts...... with an introduction to the domain of electricity consumption in private households. Second, we present related work on feedback motivated electricity conservation in private households and our relation to this research field. Third, we present methods and results from our user-driven design study. In a discussion we...

  10. Roadmap of retail electricity market reform in China: assisting in mitigating wind energy curtailment

    Science.gov (United States)

    Yu, Dezhao; Qiu, Huadong; Yuan, Xiang; Li, Yuan; Shao, Changzheng; Lin, You; Ding, Yi

    2017-01-01

    Among the renewable energies, wind energy has gained the rapidest development in China. Moreover wind power generation has been penetrated into power system in a large scale. However, the high level wind curtailment also indicates a low efficiency of wind energy utilization over the last decade in China. One of the primary constraints on the utilization of wind energy is the lack of an electricity market, in which renewable energies can compete equally with traditional fossil fuel generation. Thus the new round electric power industry reform is essential in China. The reform involves implementing new pricing mechanism, introducing retail-side competition, promoting the consumption of renewable energy. The new round reform can be a promising solution for promoting the development and consumption of wind energy generation in China. Based on proposed reform policies of electric power industry, this paper suggests a roadmap for retail electricity market reform of China, which consists of three stages. Barriers to the efficient utilization of wind energy are also analysed. Finally, this paper introduces several efficient measures for mitigating wind curtailment in each stage of reform.

  11. Fluid power network for centralized electricity generation in offshore wind farms

    NARCIS (Netherlands)

    Jarquin-Laguna, A.

    2014-01-01

    An innovative and completely different wind-energy conversion system is studied where a centralized electricity generation within a wind farm is proposed by means of a hydraulic network. This paper presents the dynamic interaction of two turbines when they are coupled to the same hydraulic network.

  12. A Wind Farm Electrical Systems Evaluation with EeFarm-II

    NARCIS (Netherlands)

    Pierik, J.; Axelsson, U.; Eriksson, E.; Salomonsson, D.; Bauer, P.; Czech, B.

    2010-01-01

    EeFarm-II is used to evaluate 13 different electrical systems for a 200 MW wind farm with a 100 km connection to shore. The evaluation is based on component manufacturer data of 2009. AC systems are compared to systems with DC connections inside the wind farm and DC connection to shore. Two options

  13. CALCULATION OF POWER AND CHOICE OF BASIC FUNCTIONAL UNITS OF WIND POWER ELECTRIC-INSTALLATION

    OpenAIRE

    Kvitko A. V.; Goncharov A. Y.

    2014-01-01

    This article discusses the basic analytical expressions for the calculation of power generators and select features basic functional units of wind turbines, allowing the design phase to conduct a preliminary assessment of the effectiveness of wind power stations, which supplies specific consumers of electric power

  14. Small Wind Electric Systems: A Rhode Island Consumer's Guide

    Energy Technology Data Exchange (ETDEWEB)

    None

    2003-06-01

    This guide provides consumers with information to help them determine whether a small wind electric system can provide all or a portion of the energy they need for their home or business based on their wind resource, energy needs, and economics.

  15. Understanding Power Electronics and Electrical Machines in Multidisciplinary Wind Energy Conversion System Courses

    Science.gov (United States)

    Duran, M. J.; Barrero, F.; Pozo-Ruz, A.; Guzman, F.; Fernandez, J.; Guzman, H.

    2013-01-01

    Wind energy conversion systems (WECS) nowadays offer an extremely wide range of topologies, including various different types of electrical generators and power converters. Wind energy is also an application of great interest to students and with a huge potential for engineering employment. Making WECS the main center of interest when teaching…

  16. Dynamic Model of a Wind Turbine for the Electric Energy Generation

    Directory of Open Access Journals (Sweden)

    José de Jesús Rubio

    2014-01-01

    Full Text Available A novel dynamic model is introduced for the modeling of the wind turbine behavior. The objective of the wind turbine is the electric energy generation. The analytic model has the characteristic that considers a rotatory tower. Experiments show the validity of the proposed method.

  17. Small Wind Electric Systems: An Oklahoma Consumer's Guide

    Energy Technology Data Exchange (ETDEWEB)

    None

    2009-01-18

    This guide provides consumers with information to help them determine whether a small wind electric system can provide all or a portion of the energy they need for their home or business based on their wind resource, energy needs, and economics.

  18. Small Wind Electric Systems: An Indiana Consumer's Guide

    Energy Technology Data Exchange (ETDEWEB)

    None

    2009-01-18

    This guide provides consumers with information to help them determine whether a small wind electric system can provide all or a portion of the energy they need for their home or business based on their wind resource, energy needs, and economics.

  19. Small Wind Electric Systems: A Michigan Consumer's Guide

    Energy Technology Data Exchange (ETDEWEB)

    None

    2009-01-18

    This guide provides consumers with information to help them determine whether a small wind electric system can provide all or a portion of the energy they need for their home or business based on their wind resource, energy needs, and economics.

  20. Small Wind Electric Systems: A Nevada Consumer's Guide

    Energy Technology Data Exchange (ETDEWEB)

    None

    2009-01-18

    This guide provides consumers with information to help them determine whether a small wind electric system can provide all or a portion of the energy they need for their home or business based on their wind resource, energy needs, and economics.

  1. Small Wind Electric Systems: A Nebraska Consumer's Guide

    Energy Technology Data Exchange (ETDEWEB)

    None

    2009-01-18

    This guide provides consumers with information to help them determine whether a small wind electric system can provide all or a portion of the energy they need for their home or business based on their wind resource, energy needs, and economics.

  2. Small Wind Electric Systems: A Missouri Consumer's Guide

    Energy Technology Data Exchange (ETDEWEB)

    None

    2009-01-18

    This guide provides consumers with information to help them determine whether a small wind electric system can provide all or a portion of the energy they need for their home or business based on their wind resource, energy needs, and economics.

  3. Small Wind Electric Systems: A Hawaii Consumer's Guide

    Energy Technology Data Exchange (ETDEWEB)

    None

    2009-01-18

    This guide provides consumers with information to help them determine whether a small wind electric system can provide all or a portion of the energy they need for their home or business based on their wind resource, energy needs, and economics.

  4. Small Wind Electric Systems: A Utah Consumer's Guide

    Energy Technology Data Exchange (ETDEWEB)

    None

    2009-01-18

    This guide provides consumers with information to help them determine whether a small wind electric system can provide all or a portion of the energy they need for their home or business based on their wind resource, energy needs, and economics.

  5. Effect of blade flutter and electrical loading on small wind turbine noise

    Science.gov (United States)

    The effect of blade flutter and electrical loading on the noise level of two different size wind turbines was investigated at the Conservation and Production Research Laboratory (CPRL) near Bushland, TX. Noise and performance data were collected on two blade designs tested on a wind turbine rated a...

  6. Technical and commercial aspects of the connection of wind turbines to electricity supply networks in Europe

    Energy Technology Data Exchange (ETDEWEB)

    Gardner, P. [Garrad Hassan & Partners Ltd., Glasgow (United Kingdom)

    1996-12-31

    This paper reviews some technical and commercial issues now topical for wind energy developments in Europe. The technical issues are important because of the weak nature of the existing electricity systems in rural or upland areas. Several commercial issues are considered which may improve the economics of wind energy as market incentives are gradually withdrawn. 9 refs.

  7. Electric Generators Fitted to Wind Turbine Systems: An Up-to-Date Comparative Study

    OpenAIRE

    Lebsir, A; Bentounsi, A; Benbouzid, Mohamed; Mangel, H

    2015-01-01

    International audience; This paper describes a comparative study allowing the selection of the most appropriate innovative structures for electrical machines for a wind turbine system. This study is based on an exhaustive review of the state of the art and on an effective comparison of the performances of the three main conventional electric generator in wind energy application system that are the Doubly-Fed Induction Generator (DFIG), the Squirrel-Cage Induction Generator (SCIG), the Permane...

  8. Influence of offshore wind farms layout on electrical resonances

    DEFF Research Database (Denmark)

    Holdyk, Andrzej; Holbøll, Joachim; Koldby, Erik

    2014-01-01

    , harmonics and interaction between components and the power system and especially on the interaction and resonance between the transformer,-cables and the circuit breaker. These phenomena are also important in offshore wind farms, where the specific and often complex structure of the collection grid can......, winding resistances and winding capacitances. Considering the frequency range of the present investigations, up to about 1 MHz, a lumped representation of the transformer characteristics was deemed sufficient. Breakers and capacitors are modelled as ideal components. The chosen wind farm layout includes...

  9. Electric industry restructuring, ancillary services, and the potential impact on wind

    Energy Technology Data Exchange (ETDEWEB)

    Kirby, B.; Hirst, E. [Oak Ridge National Lab., TN (United States); Parsons, B.; Porter, K. [National Renewable Energy Lab., Golden, CO (United States)] [and others

    1997-12-31

    The new competitive electric power environment raises increased challenges for wind power. The DOE and EPRI wind programs have dealt extensively with the traditional vertically integrated utility planning and operating environment in which the host utility owns the generation (or purchases the power) and provides dispatch and transmission services. Under this traditional environment, 1794 MW of wind power, principally in California, have been successfully integrated into the U.S. electric power system. Another 4200 MW are installed elsewhere in the world. As issues have arisen, such as intermittency and voltage regulation, they have been successfully addressed with accepted power system procedures and practices. For an intermittent, non-dispatchable resource such as wind, new regulatory rules affecting power transmission services, raise questions about which ancillary services wind plants will be able to sell, which they will be required to purchase, and what the economic impacts will be on individual wind projects. This paper begins to look at issues of concern to wind in a restructured electric industry. The paper first briefly looks at the range of unbundled services and comments on their unique significance to wind. To illustrate the concerns that arise with restructuring, the paper then takes a more detailed look at a single service: regulation. Finally, the paper takes a brief look at technologies and strategies that could improve the competitive position of wind.

  10. Electric Field Driven Self-Assembly of Colloidal Rods

    Science.gov (United States)

    Juarez, Jaime; Chaudhary, Kundan; Chen, Qian; Granick, Steve; Lewis, Jennifer

    2012-02-01

    The ability to assemble anisotropic colloidal building blocks into ordered configurations is of both scientific and technological importance. We are studying how electric field-induced interactions guide the self-assembly of these blocks into well aligned microstructures. Specifically, we present observations of the assembly of colloidal silica rods (L/D ˜ 4) within planar electrode cells as a function of different electric field parameters. Results from video microscopy and image analysis demonstrate that aligned microstructures form due to the competition between equilibrium interactions of induced dipoles and non-equilibrium processes (i.e., electro-osmosis). Under the appropriate electric field conditions (˜ kHZ AC fields), aligned colloidal rod fluids form over large areas on the electrode surface. The superposition of a DC electric field to this aligned colloidal rod fluid initiates their condensation into a vertically oriented crystalline phase. Ongoing work is now focused on exploring how temporal changes to electric fields influence colloidal rod dynamics and, hence, the assembly kinetics of aligned colloidal monolayers.

  11. Wind energy, electricity, and hydrogen in the Netherlands

    NARCIS (Netherlands)

    Schenk, Niels J.; Moll, Henri C.; Potting, José; Benders, René M.J.

    2007-01-01

    The curbing of greenhouse gases (GHG) is an important issue on the international political agenda. The substitution of fossil fuels by renewable energy sources is an often-advocated mitigation strategy. Wind energy is a potential renewable energy source. However, wind energy is not reliable since

  12. statistical analysis of wind speed for electrical power generation in ...

    African Journals Online (AJOL)

    HOD

    are employed to fit wind speed data of some selected sites in Northern Nigeria. This is because the design of wind energy conversion systems depends on the correct analysis of the site renewable energy resources. [13]. In addition, the statistical judgements are based on the accuracy in fitting the available data at the sites.

  13. Statistical analysis of wind speed for electrical power generation in ...

    African Journals Online (AJOL)

    Also, the results have shown that Jos, Kano and Minna fall in class 4 and therefore suitable for both off grid and grid connected modes. In addition, the effects of c and k parameters on the probability distribution functions have been presented. Keywords: Wind speed - probability - density function – wind energy conversion ...

  14. Wind Power in Ontario: Its Contribution to the Electricity Grid

    Science.gov (United States)

    Rowlands, Ian H.; Jernigan, Carey

    2008-01-01

    The purpose of this article is to investigate wind turbine production, the variability of that production, and the relationship between output and system-wide demand. A review of the literature reveals that a variety of measures (and methods) to explore the variability of wind power production exist. Attention then turns to the province of Ontario…

  15. Investigation of the Promotion of Wind Power Consumption Using the Thermal-Electric Decoupling Techniques

    Directory of Open Access Journals (Sweden)

    Shuang Rong

    2015-08-01

    Full Text Available In the provinces of north China, combined heat and electric power generations (CHP are widely utilized to provide both heating source and electricity. While, due to the constraint of thermal-electric coupling within CHP, a mass of wind turbines have to offline operate during heating season to maintain the power grid stability. This paper proposes a thermal-electric decoupling (TED approach to release the energy waste. Within the thermal-electric decoupling system, heat storage and electric boiler/heat pump are introduced to provide an auxiliary thermal source during hard peak shaving period, thus relying on the participation of an outside heat source, the artificial electric power output change interval could be widened to adopt more wind power and reduce wind power curtailment. Both mathematic models and methods are proposed to calculate the evaluation indexes to weight the effect of TED, by using the Monte Carlo simulation technique. Numerical simulations have been conducted to demonstrate the effectiveness of the proposed methods, and the results show that the proposed approach could relieve up to approximately 90% of wind power curtailment and the ability of power system to accommodate wind power could be promoted about 32%; moreover, the heating source is extended, about 300 GJ heat could be supplied by TED during the whole heating season, which accounts for about 18% of the total heat need.

  16. Determining an energy-optimal thermal management strategy for electric driven vehicles

    Energy Technology Data Exchange (ETDEWEB)

    Suchaneck, Andre; Probst, Tobias; Puente Leon, Fernando [Karlsruher Institut fuer Technology (KIT), Karlsruhe (Germany). Inst. of Industrial Information Technology (IIIT)

    2012-11-01

    In electric, hybrid electric and fuel cell vehicles, thermal management may have a significant impact on vehicle range. Therefore, optimal thermal management strategies are required. In this paper a method for determining an energy-optimal control strategy for thermal power generation in electric driven vehicles is presented considering all controlled devices (pumps, valves, fans, and the like) as well as influences like ambient temperature, vehicle speed, motor and battery and cooling cycle temperatures. The method is designed to be generic to increase the thermal management development process speed and to achieve the maximal energy reduction for any electric driven vehicle (e.g., by waste heat utilization). Based on simulations of a prototype electric vehicle with an advanced cooling cycle structure, the potential of the method is shown. (orig.)

  17. Optimisation of electrical system for offshore wind farms via genetic algorithm

    DEFF Research Database (Denmark)

    Chen, Zhe; Zhao, Menghua; Blaabjerg, Frede

    2009-01-01

    An optimisation platform based on genetic algorithm (GA) is presented, where the main components of a wind farm and key technical specifications are used as input parameters and the electrical system design of the wind farm is optimised in terms of both production cost and system reliability....... The power losses, wind power production, initial investment and maintenance costs are considered in the production cost. The availability of components and network redundancy are included in the reliability evaluation. The method of coding an electrical system to a binary string, which is processed by GA...

  18. Electricity network limitations on large-scale deployment of wind energy

    Energy Technology Data Exchange (ETDEWEB)

    Fairbairn, R.J.

    1999-07-01

    This report sought to identify limitation on large scale deployment of wind energy in the UK. A description of the existing electricity supply system in England, Scotland and Wales is given, and operational aspects of the integrated electricity networks, licence conditions, types of wind turbine generators, and the scope for deployment of wind energy in the UK are addressed. A review of technical limitations and technical criteria stipulated by the Distribution and Grid Codes, the effects of system losses, and commercial issues are examined. Potential solutions to technical limitations are proposed, and recommendations are outlined.

  19. DESIGN AND DEVELOPMENT OF A 1/3 SCALE VERTICAL AXIS WIND TURBINE FOR ELECTRICAL POWER GENERATION

    OpenAIRE

    Altab Hossain; A.K.M.P. Iqbal; Ataur Rahman; M. Arifin; M. Mazian

    2007-01-01

    This research describes the electrical power generation in Malaysia by the measurement of wind velocity acting on the wind turbine technology. The primary purpose of the measurement over the 1/3 scaled prototype vertical axis wind turbine for the wind velocity is to predict the performance of full scaled H-type vertical axis wind turbine. The electrical power produced by the wind turbine is influenced by its two major part, wind power and belt power transmission system. The blade and the drag...

  20. Intensity statistics of very high frequency sound scattered from wind-driven waves.

    Science.gov (United States)

    Walstead, Sean P; Deane, Grant B

    2016-05-01

    The interaction of vhf 100-1000 kHz underwater sound with the ocean surface is explored. The bistatic forward scatter of 300 kHz sound is measured in a wind driven wave channel. Fluctuations in arrival amplitude are described by the scintillation index (SI) which is a measure of arrival intensity variance. SI initially increases with wind speed but eventually saturates to a value of 0.5 when the root-mean-square (rms) roughness is 0.5 mm. An adjusted scintillation index (SI*) is suggested that accounts for the multiple arrivals and properly saturates to a value of 1. Fluctuations in arrival time do not saturate and increase proportionately to the dominant surface wave component. Forward scattering is modeled at frequencies ranging from 50 to 2000 kHz using the Helmholtz-Kirchhoff integral with surface wave realizations derived from wave gauge data. The amplitude and temporal statistics of the simulated scattering agree well with measured data. Intensity saturation occurs at lower wind speeds for higher frequency sound. Both measured and modeled vhf sound is characterized by many surface arrivals at saturation. Doppler shifts associated with wave motion are expected to vary rapidly for vhf sound however further analysis is required.

  1. Tsunami-driven gravity waves in the presence of vertically varying background and tidal wind structures

    Science.gov (United States)

    Laughman, B.; Fritts, D. C.; Lund, T. S.

    2017-05-01

    Many characteristics of tsunami-driven gravity waves (TDGWs) enable them to easily propagate into the thermosphere and ionosphere with appreciable amplitudes capable of producing detectable perturbations in electron densities and total electron content. The impact of vertically varying background and tidal wind structures on TDGW propagation is investigated with a series of idealized background wind profiles to assess the relative importance of wave reflection, critical-level approach, and dissipation. These numerical simulations employ a 2-D nonlinear anelastic finite-volume neutral atmosphere model which accounts for effects accompanying vertical gravity wave (GW) propagation such as amplitude growth with altitude. The GWs are excited by an idealized tsunami forcing with a 50 cm sea surface displacement, a 400 km horizontal wavelength, and a phase speed of 200 ms-1 consistent with previous studies of the tsunami generated by the 26 December 2004 Sumatra earthquake. Results indicate that rather than partial reflection and trapping, the dominant process governing TDGW propagation to thermospheric altitudes is refraction to larger and smaller vertical scales, resulting in respectively larger and smaller vertical group velocities and respectively reduced and increased viscous dissipation. Under all considered background wind profiles, TDGWs were able to attain ionospheric altitudes with appreciable amplitudes. Finally, evidence of nonlinear effects is observed and the conditions leading to their formation is discussed.

  2. Design and optimization of 8 MW directly driven surface mounted permanent magnet wind generators

    Energy Technology Data Exchange (ETDEWEB)

    Shanming, W. [Tsinghua Univ., Beijing (China). Inst. of Power Electronics and Electrical Machine System, State Key Lab of Power Systems, Dept. of Electrical Engineering; Schaefer, U. [Univ. of Technlogy, Berlin (Germany). Inst. of Energy and Automation, Dept. of Electrical Drive Technology

    2007-07-01

    An 8 MW directly-driven surface-mounted permanent magnet synchronous wind generator was described. The electromagnetic field (EMF), armature reaction reactance, and different parts of the generator's leakage reactance were analyzed in order to optimize the generator. Air gap shear stress was measured and optimized in order to increase the power density of the generator. Pole pair numbers were optimized and slot numbers were determined in order to increase generator performance. Parallel branch numbers were set to reduce mechanical errors. The height of the permanent magnet was set to resist the demagnetization effect of stator currents under normal and fault conditions. Slot leakage inductance was decreased while the slot fill factor was set at 0.5. Parameters and performance of the generator were then analyzed using SPEED software. The optimization study showed that the power factor was 0.909 when the generator's rated power of 8 MW was reached. The study also demonstrated that leakage reactances play an important role in total synchronous reactances. Formulae were then developed to accurately calculate winding and differential leakage reactance. Designs with various core lengths, pole pair numbers, and stator windings were modelled using the program. It was concluded that more than 50 per cent of the synchronous reactance is comprised of total leakage reactance. Airgap shear stress for the design was set at 55 kPa. 14 refs., 4 tabs., 2 figs.

  3. Earthward Flow Bursts in the Magnetotail Driven by Solar Wind Pressure Impulse

    Directory of Open Access Journals (Sweden)

    Khan-Hyuk Kim

    2008-12-01

    Full Text Available On August 31, 2001, ~ 1705 - 1718 UT, Cluster was located near the midnight magnetotail, GSE (x, y, z ~ (-19, - 2,2 RE, and observed fast earthward flow bursts in the vicinity of the neutral sheet. They occurred while the tail magnetic field suddenly increased. Using simultaneous measurements in the solar wind, at geosynchronous orbit, and on the ground, it is confirmed that tail magnetic field enhancement is due to an increased solar wind pressure. In the neutral sheet region, strongly enhanced earthward flow bursts perpendicular to the local magnetic field (V_(⊥x were observed. Auroral brightenings localized in the pre-midnight sector (~ 2200 - 2400 MLT occurred during the interval of the V_(⊥x enhancements. The V_(⊥x bursts started ~2 minutes before the onset of auroral brightenings. Our observations suggest that the earthward flow bursts are associated with tail reconnection directly driven by a solar wind pressure impulse and that V_(⊥x caused localized auroral brightenings.

  4. Red Geyser: A New Class of Galaxy with Large-scale AGN-driven Winds

    Science.gov (United States)

    Roy, Namrata; Bundy, Kevin; Cheung, Edmond; MaNGA Team

    2018-01-01

    A new class of quiescent (non-star-forming) galaxies harboring possible AGN-driven winds have been discovered using the spatially resolved optical spectroscopy from the ongoing SDSS-IV MaNGA (Sloan Digital Sky Survey-IV Mapping Nearby Galaxies at Apache Point Observatory) survey. These galaxies named "red geysers" constitute 5%-10% of the local quiescent galaxy population and are characterized by narrow bisymmetric ionized gas emission patterns. These enhanced patterns are seen in equivalent width maps of Hα, [OIII] and other strong emission lines. They are co-aligned with the ionized gas velocity gradients but significantly misaligned with stellar velocity gradients. They also show very high gas velocity dispersions (~200 km/s). Considering these observations in light of models of the gravitational potential, Cheung et al. argued that red geysers host large-scale AGN-driven winds of ionized gas that may play a role in suppressing star formation at late times. In this work, we test the hypothesis that AGN activity is ultimately responsible for the red geyser phenomenon. We compare the nuclear radio activity of the red geysers to a matched control sample of galaxies of similar stellar mass, redshift, rest frame NUV–r color and axis ratio. and additionally, control for the presence of ionized gas. We have used 1.4 GHz radio continuum data from the VLA FIRST Survey to stack the radio flux from the red geyser sample and control sample. We find that the red geysers have a higher average radio flux than the control galaxies at > 3σ significance. Our sample is restricted to rest-frame NUV–r color > 5, thus ruling out possible radio emission due to star formation activity. We conclude that red geysers are associated with more active AGN, supporting a feedback picture in which episodic AGN activity drives large-scale but relatively weak ionized winds in many in many early-type galaxies.

  5. Lidar observations of wind- and wave-driven morphological evolution of coastal foredunes

    Science.gov (United States)

    Spore, N.; Brodie, K. L.; Kershner, C. M.

    2016-02-01

    Coastal foredunes are continually evolving geomorphic features that are slowly built up by wind-blown sand and rapidly eroded during storms by large waves and swash. Landward aeolian transport removes sediment from the active beach and surf-zone, trapping it in the dune, where as coastal erosion both removes sediment from the dune and can decrease the overall fetch and sediment supply available to the dune. Understanding how wave and wind-driven process interact with each other and the dune-beach system itself is a critical component of improving predictions of coastal evolution. To investigate these processes, two 50 m alongshore by 25 m cross-shore patches of dune along an open coast beach fronting the Atlantic Ocean in Duck, NC were scanned with a high resolution terrestrial lidar scanner ( 5000 points per m^2) every three weeks over the last year to observe detailed morphological evolution of the dune and upper beach. Sequential scans were co-registered to each other using fixed objects in the field of view, significantly increasing precision and accuracy of the observations. The north study site featured a 7.5 m tall scarped foredune system, where as the southern study site featured a 6 m tall, hummocky, prograding foredune. Initial analyses show large accretion events on the southern prograding site. For example, during one three week period in February, portions of the site accreted over 40 cm. In contrast, during the same three week period at the northern site (less than 1 km away), response was alongshore variable with erosion and accretion of roughly 10 cm on the foredune face. Further analysis will focus on separating wind vs. wave driven evolution of these sites. Funded by the USACE Coastal Inlets Research Program.

  6. Power System Modeling of 20percent Wind-Generated Electricity by 2030

    Energy Technology Data Exchange (ETDEWEB)

    Bolinger, Mark A; Hand, Maureen; Blair, Nate; Bolinger, Mark; Wiser, Ryan; Hern, Tracy; Miller, Bart; O& #39; Connell, R.

    2008-06-09

    The Wind Energy Deployment System model was used to estimate the costs and benefits associated with producing 20% of the nation's electricity from wind technology by 2030. This generation capacity expansion model selects from electricity generation technologies that include pulverized coal plants, combined cycle natural gas plants, combustion turbine natural gas plants, nuclear plants, and wind technology to meet projected demand in future years. Technology cost and performance projections, as well as transmission operation and expansion costs, are assumed. This study demonstrates that producing 20% of the nation's projected electricity demand in 2030 from wind technology is technically feasible, not cost-prohibitive, and provides benefits in the forms of carbon emission reductions, natural gas price reductions, and water savings.

  7. Contrasting Electricity Demand with Wind Power Supply: Case Study in Hungary

    Directory of Open Access Journals (Sweden)

    Imre M. Jánosi

    2009-09-01

    Full Text Available We compare the demand of a large electricity consumer with supply given by wind farms installed at two distant geographic locations. Obviously such situation is rather unrealistic, however our main goal is a quantitative characterization of the intermittency of wind electricity. The consumption pattern consists of marked daily and weekly cycles interrupted by periods of holidays. In contrast, wind electricity production has neither short-time nor seasonal periodicities. We show that wind power integration over a restricted area cannot provide a stable baseload supply, independently of the excess capacity. Further essential result is that the statistics are almost identical for a weekly periodic pattern of consumption and a constant load of the same average value. The length of both adequate supply and shortfall intervals exhibits a scale-free (power-law frequency distribution, possible consequences are shortly discussed.

  8. An parametric investigation into the effect of low induction rotor (LIR) wind turbines on the levelised cost of electricity of a 1 GW offshore wind farm in a North Sea wind climate

    NARCIS (Netherlands)

    B. Bulder; Gerard Schepers; R. Quinn

    In this report, the details of an investigation into the eect of the low induction wind turbines on the Levelised Cost of Electricity (LCoE) in a 1GW oshore wind farm is outlined. The 10 MW INNWIND.EU conventional wind turbine and its low induction variant, the 10 MW AVATAR wind turbine, are

  9. European Short-term Electricity Market Designs under High Penetration of Wind Power

    NARCIS (Netherlands)

    Chaves Avila, J.P.

    2014-01-01

    The EU has ambitious policies for decarbonization of the electricity sector. Due to recent technological developments, wind power already represents a significant share of the generation mix in some European countries. As a result, short-term electricity markets and balancing arrangements must be

  10. Comparison of electrically driven lasers for space power transmission

    Science.gov (United States)

    Deyoung, R. J.; Lee, J. H.; Williams, M. D.; Schuster, G.; Conway, E. J.

    1988-01-01

    High-power lasers in space could provide power for a variety of future missions such as spacecraft electric power requirements and laser propulsion. This study investigates four electrically pumped laser systems, all scaled to 1-MW laser output, that could provide power to spacecraft. The four laser systems are krypton fluoride, copper vapor, laser diode array, and carbon dioxide. Each system was powered by a large solar photovoltaic array which, in turn, provided power for the appropriate laser power conditioning subsystem. Each system was block-diagrammed, and the power and efficiency were found for each subsystem block component. The copper vapor system had the lowest system efficiency (6 percent). The CO2 laser was found to be the most readily scalable but has the disadvantage of long laser wavelength.

  11. Implementation, Comparison and Application of an Average Simulation Model of a Wind Turbine Driven Doubly Fed Induction Generator

    Directory of Open Access Journals (Sweden)

    Lidula N. Widanagama Arachchige

    2017-10-01

    Full Text Available Wind turbine driven doubly-fed induction generators (DFIGs are widely used in the wind power industry. With the increasing penetration of wind farms, analysis of their effect on power systems has become a critical requirement. This paper presents the modeling of wind turbine driven DFIGs using the conventional vector controls in a detailed model of a DFIG that represents power electronics (PE converters with device level models and proposes an average model eliminating the PE converters. The PSCAD/EMTDC™ (4.6 electromagnetic transient simulation software is used to develop the detailed and the proposing average model of a DFIG. The comparison of the two models reveals that the designed average DFIG model is adequate for simulating and analyzing most of the transient conditions.

  12. Bidirectional ionic wind in nonpremixed counterflow flames with DC electric fields

    KAUST Repository

    Park, Daegeun

    2016-05-05

    Under an electric field, ions in the reaction zone of a flame generate a bulk flow motion called ionic wind. Because the majority of ions are positive, ionic wind is commonly considered to be unidirectional toward the cathode. A more thorough understanding of the effects of electric fields on flames could be obtained by clarifying the role of minor negative ions in the ionic wind. Here, we report on the effects of direct current on nonpremixed counterflow flames by visualizing the ionic wind. We found that the original flow field separates near the flame when it locates at a flow stagnation plane, resulting in a double-stagnant flow configuration. This evidences a bidirectional ionic wind blowing from the flame to both the cathode and the anode due to the positive and the negative ions, respectively. Meanwhile, an electric body force pulls the flame toward the cathode. Thus, the electric field affects the strain rate and the axial location of the stoichiometry, which are important for characterizing nonpremixed counterflow flames. In addition, measurement of the electric current density roughly showed a nearly saturated current when these flames restabilized under relatively high voltage. Detailed explanations of flame behavior, electric currents, and flow characteristics of various fuels are discussed in this study.

  13. MAGNETICALLY DRIVEN ACCRETION DISK WINDS AND ULTRA-FAST OUTFLOWS IN PG 1211+143

    Energy Technology Data Exchange (ETDEWEB)

    Fukumura, Keigo [James Madison University, Harrisonburg, VA 22807 (United States); Tombesi, Francesco; Kazanas, Demosthenes; Shrader, Chris [Astrophysics Science Division, NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Behar, Ehud [Department of Physics, Technion, Haifa 32000 (Israel); Contopoulos, Ioannis, E-mail: fukumukx@jmu.edu [Research Center for Astronomy, Academy of Athens, Athens 11527 (Greece)

    2015-05-20

    We present a study of X-ray ionization of MHD accretion-disk winds in an effort to constrain the physics underlying the highly ionized ultra-fast outflows (UFOs) inferred by X-ray absorbers often detected in various sub classes of Seyfert active galactic nuclei (AGNs). Our primary focus is to show that magnetically driven outflows are indeed physically plausible candidates for the observed outflows accounting for the AGN absorption properties of the present X-ray spectroscopic observations. Employing a stratified MHD wind launched across the entire AGN accretion disk, we calculate its X-ray ionization and the ensuing X-ray absorption-line spectra. Assuming an appropriate ionizing AGN spectrum, we apply our MHD winds to model the absorption features in an XMM-Newton/EPIC spectrum of the narrow-line Seyfert, PG 1211+143. We find, through identifying the detected features with Fe Kα transitions, that the absorber has a characteristic ionization parameter of log (ξ{sub c}[erg cm s{sup −1}]) ≃ 5–6 and a column density on the order of N{sub H} ≃ 10{sup 23} cm{sup −2} outflowing at a characteristic velocity of v{sub c}/c ≃ 0.1–0.2 (where c is the speed of light). The best-fit model favors its radial location at r{sub c} ≃ 200 R{sub o} (R{sub o} is the black hole’s innermost stable circular orbit), with an inner wind truncation radius at R{sub t} ≃ 30 R{sub o}. The overall K-shell feature in the data is suggested to be dominated by Fe xxv with very little contribution from Fe xxvi and weakly ionized iron, which is in good agreement with a series of earlier analyses of the UFOs in various AGNs, including PG 1211+143.

  14. The Electric Wind of Venus: A global and persistent "polar wind" like ambipolar electric field sufficient for the direct escape of heavy ionospheric ions

    Science.gov (United States)

    Collinson, G.; Frahm, R.; Glocer, A.; Coates, A. J.; Grebowsky, J. M.; Barbash, S.; Fedorov, A.; Futaana, Y.; Gilbert, L.; Khazanov, G. V.; Domagal-Goldman, S. D.; Nordheim, T.; Mitchell, D. L.; Moore, T. E.; Peterson, W.; Winningham, D.; Zhang, T.

    2016-12-01

    Understanding what processes govern atmospheric escape and the loss of planetary water is of paramount importance for understanding how life in the universe can exist. One mechanism thought to be important at all planets is an "ambipolar" electric field that helps ions overcome gravity. We report the discovery and first quantitative extraterrestrial measurements of such a field at the planet Venus. Unexpectedly, despite comparable gravity, we show the field to be five times stronger than in Earth's similar ionosphere. Contrary to our understanding, Venus would still lose heavy ions (including oxygen and all water-group species) to space, even if there were no stripping by the solar wind. We therefore find it is possible for planets to lose heavy ions to space entirely through electric forces in their ionospheres, and such an "electric wind" must be considered when studying the evolution and potential habitability of any planet in any star system

  15. The Electric Wind of Venus: A Global and Persistent Polar Wind -Like Ambipolar Electric Field Sufficient for the Direct Escape of Heavy Ionospheric Ions

    Science.gov (United States)

    Collinson, Glyn A.; Frahm, Rudy A.; Glocer, Alex; Coates, Andrew J.; Grebowsky, Joseph M.; Barabash, Stas; Domagal-Goldman, Shawn D.; Federov, Andrei; Futaana, Yoshifumi; Gilbert, Lin K.; hide

    2016-01-01

    Understanding what processes govern atmospheric escape and the loss of planetary water is of paramount importance for understanding how life in the universe can exist. One mechanism thought to be important at all planets is an ambipolar electric field that helps ions overcome gravity. We report the discovery and first quantitative extraterrestrial measurements of such a field at the planet Venus. Unexpectedly, despite comparable gravity, we show the field to be five times stronger than in Earths similar ionosphere. Contrary to our understanding, Venus would still lose heavy ions (including oxygen and all water-group species) to space, even if there were no stripping by the solar wind. We therefore find that it is possible for planets to lose heavy ions to space entirely through electric forces in their ionospheres and such an electric wind must be considered when studying the evolution and potential habitability of any planet in any star system.

  16. Optimization of Electrical System for a Large DC Offshore Wind Farm by Genetic Algorithm

    DEFF Research Database (Denmark)

    Zhao, Menghua; Chen, Zhe; Blaabjerg, Frede

    2004-01-01

    This paper proposes an optimization platform based on Genetic Algorithm, where the main components of the electrical system of a wind farm and key technical specifications are used as input parameters and the topology of the electrical system is to be optimized for a minimum cost and high...... reliability. A method to encode and decode an electrical system is studied. The reliability evaluation for a given network is also investigated. Genetic Algorithm is implemented to find the optimum network design for a large DC wind farm. It is concluded that different topologies may cause very different cost...

  17. Electricity from Wind for Off-Grid Applications in Bangladesh: A Techno-Economic Assessment

    Directory of Open Access Journals (Sweden)

    Md. Mustafizur Rahman

    2017-03-01

      Keywords: GHG emission, cost of electricity, off-grid, wind energy, electricity generation. Article History: Received October 15th 2016; Received in revised form January 26th 2017; Accepted February 4th 2017; Available online How to Cite This Article: Rahman, M.M., Baky, M.A.H, and Islam, A.K.M.S. (2017 Electricity from Wind for Off-Grid Applications in Bangladesh: A Techno-Economic Assessment. International Journal of Renewable Energy Develeopment, 6(1, 55-64. http://dx.doi.org/10.14710/ijred.6.1.55-64

  18. Proactive monitoring of a wind turbine array with lidar measurements, SCADA data and a data-driven RANS solver

    Science.gov (United States)

    Iungo, G.; Said, E. A.; Santhanagopalan, V.; Zhan, L.

    2016-12-01

    Power production of a wind farm and durability of wind turbines are strongly dependent on non-linear wake interactions occurring within a turbine array. Wake dynamics are highly affected by the specific site conditions, such as topography and local atmospheric conditions. Furthermore, contingencies through the life of a wind farm, such as turbine ageing and off-design operations, make prediction of wake interactions and power performance a great challenge in wind energy. In this work, operations of an onshore wind turbine array were monitored through lidar measurements, SCADA and met-tower data. The atmospheric wind field investing the wind farm was estimated by using synergistically the available data through five different methods, which are characterized by different confidence levels. By combining SCADA data and the lidar measurements, it was possible to estimate power losses connected with wake interactions. For this specific array, power losses were estimated to be 4% and 2% of the total power production for stable and convective atmospheric regimes, respectively. The entire dataset was then leveraged for the calibration of a data-driven RANS (DDRANS) solver for prediction of wind turbine wakes and power production. The DDRANS is based on a parabolic formulation of the Navier-Stokes equations with axisymmetry and boundary layer approximations, which allow achieving very low computational costs. Accuracy in prediction of wind turbine wakes and power production is achieved through an optimal tuning of the turbulence closure model. The latter is based on a mixing length model, which was developed based on previous wind turbine wake studies carried out through large eddy simulations and wind tunnel experiments. Several operative conditions of the wind farm under examination were reproduced through DDRANS for different stability regimes, wind directions and wind velocity. The results show that DDRANS is capable of achieving a good level of accuracy in prediction

  19. Interplanetary and Interstellar Dust Observed by the Wind/WAVES Electric Field Instrument

    Science.gov (United States)

    Malaspina, David; Horanyi, M.; Zaslavsky, A.; Goetz, K.; Wilson, L. B., III; Kersten, K.

    2014-01-01

    Observations of hypervelocity dust particles impacting the Wind spacecraft are reported here for the first time using data from the WindWAVES electric field instrument. A unique combination of rotating spacecraft, amplitude-triggered high-cadence waveform collection, and electric field antenna configuration allow the first direct determination of dust impact direction by any spacecraft using electric field data. Dust flux and impact direction data indicate that the observed dust is approximately micron-sized with both interplanetary and interstellar populations. Nanometer radius dust is not detected by Wind during times when nanometer dust is observed on the STEREO spacecraft and both spacecraft are in close proximity. Determined impact directions suggest that interplanetary dust detected by electric field instruments at 1 AU is dominated by particles on bound trajectories crossing Earths orbit, rather than dust with hyperbolic orbits.

  20. Electricity for Road Transport, Flexible Power Systems and Wind Power

    DEFF Research Database (Denmark)

    Nielsen, Lars Henrik; Ravn, Hans; Meibom, Peter

    The aim of the project is to analyse the potential synergistic interplay that may arise between the power sector and the transport sector, if parts of the road transport energy needs are based on electricity via the utilisation of plug-in hybrid electric vehicles and pure electric vehicles......-vehicle connection systems including technical regulation options and analysis of needs for standardisation. 4: Setting up scenarios covering potential developments for utilizing electric drive trains in road transport. Period: Up to year 2030. 5: Analysis of capacity constraints in the electricity grid...

  1. Modal Analysis of In-Wheel Motor-Driven Electric Vehicle Based on Bond Graph Theory

    Directory of Open Access Journals (Sweden)

    Di Tan

    2017-01-01

    Full Text Available A half-car vibration model of an electric vehicle driven by rear in-wheel motors was developed using bond graph theory and the modular modeling method. Based on the bond graph model, modal analysis was carried out to study the vibration characteristics of the electric vehicle. To verify the effectiveness of the established model, the results were compared to ones computed on the ground of modal analysis and Newton equations. The comparison shows that the vibration model of the electric vehicle based on bond graph theory not only is able to better compute the natural frequency but also can easily determine the deformation mode, momentum mode, and other isomorphism modes and describe the dynamic characteristics of an electric vehicle driven by in-wheel motors more comprehensively than other modal analysis methods.

  2. The wind and thermally driven circulation of the eastern Mediterranean Sea. Part II: the Baroclinic case

    Science.gov (United States)

    Malanotte-Rizzoli, Paola; Bergamasco, Andrea

    1991-04-01

    Compared with other interesting parts of the World Ocean, little is known of the eastern Mediterranean and major issues of the Mediterranean circulation are still unsolved. Among them, the most crucial one is: what is the dominant driving mechanism of the eastern Mediterranean general circulation: (1) the wind stress; (2) the thermohaline surface fluxes; (3) the inflow forcing at the Sicily Straits? What is the relative importance of these three forcing functions? Is it the same in the different sub-basins comprising the eastern Mediterranean? What modelling factors are important for the simulation of the seasonal cycle and is the general circulation overall dominated by the annual mean or seasonal signal? To answer the above questions we have carried out an extensive and thorough series of numerical experiments using a multilevel model of the circulation, suitable for coarse-resolution studies but endowed with active thermodynamics and allowing for realistic geometry (coastlines, islands, bottom relief). The model is used in a three-level version as the minimum one capable of simulating the vertical superposition of different water masses observed in the eastern Mediterranean. The climatological monthly averages of wind-stress, thermal and evaporative fluxes and inflow at Sicily are used to drive the model. In Part I of the present study it was shown that the seasonal cycle present in the wind-stress curl induces a strongly seasonal barotropic circulation comprising the entire eastern Mediterranean. This seasonal gyre reverses from being cyclonic in winter to anticyclonic in summer. The inclusion of baroclinicity, however, profoundly modifies the purely wind-driven, barotropic circulation, eliminating the strong seasonality and the winter-to-summer reversal. The first important result is that the general circulation pattern now consists of a succession of sub-basin-scale gyres, with a seasonal modulation emphasizing the cyclonic centres in winter and the

  3. Policy instruments for regulating the development of wind power in a liberated electricity market

    Energy Technology Data Exchange (ETDEWEB)

    Morthorst, P.E. [Risoe National Lab., Roskilde (Denmark)

    1999-03-01

    Wind power is facing the dual challenge of entering a liberated electricity market and at the same time being one of the main contributors to the reduction of greenhouse gas emissions. The paper analyses the importance of the existing standard payment schemes in the development of wind power, and how this might be affected by the introduction of a liberated electricity market. The existing Danish standard payment scheme has strongly encouraged investments in wind turbines. It has been and still is very effective in promoting a high wind power capacity development, but at a high economic cost to the Danish Government. Different models of conditions for wind power at an electricity exchange do exist, but all seem to introduce a higher risk to the individual wind turbine owner than seen with the present payment scheme. In short it might be stated that going from the existing standard payment system to a market based system, the political uncertainty is converted to a market risk for the individual wind turbine owner. (au)

  4. Performance of a 10 kilowatt wind-electric water pumping system for irrigating crops

    Energy Technology Data Exchange (ETDEWEB)

    Vick, B.D.; Clark, R.N. [Conservation and Production Research Lab., Bushland, TX (United States); Molla, S. [Texas A& M Univ., College Station, TX (United States)

    1997-12-31

    A 10 kW wind-electric water pumping system was tested for field crop irrigation at pumping depths from 50 to 120 m. The wind turbine for this system used a permanent magnet alternator that powered off-the-shelf submersible motors and pumps without the use of an inverter. Pumping performance was determined at the USDA-Agricultural Research Service (ARS), Wind Energy Laboratory in Bushland, TX for the 10 kW wind turbine using a pressure valve and a pressure tank to simulate different pumping depths. Pumping performance was measured for two 10 kW wind turbines of the same type at farms near the cities of Garden City, TX and Stiles, TX. The pumping performance data collected at these actual wells compared favorably with the data collected at the USDA-ARS, Wind Energy Laboratory. If utility generated electricity was accessible, payback on the wind turbine depended on the cost of utility generated electricity and the transmission line extension cost.

  5. Improving energy security and reducing greenhouse gas emissions using wind-electricity and storage heaters

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, Larry; Lakshminarayanan, Hari [Dalhousie Univ., Halifax, NS (Canada). Electrical and Computer Engineering

    2012-07-01

    The world economic crisis and volatile world energy markets are making energy security a challenge in most jurisdictions. This is especially true of communities with lengthy heating seasons and limited domestic energy resources which rely heavily on imported energy to meet their space heating requirements. This paper describes how the City of Summerside in the Canadian province of Prince Edward Island installed a 12 MW wind-farm and a number of electric thermal-storage heaters and domestic hot water units to demonstrate the viability of using a variable source of electricity, the wind, to heat residential structures. The decision was taken to both improve energy security and reduce greenhouse gas emissions, since Summerside relies on light-fuel oil to meet over 80% of its residential heating demand, adding to the community's greenhouse gas emissions. Given the need to utilize wind-electricity both efficiently and effectively, the paper introduces five methods for the control and allocation of wind-electricity. It shows that although Summerside has opted for recharging the thermal storage units during the overnight hours, the test households would meet most of their heating needs if they were to be available for recharging throughout the day. The paper also examines some of the shortcomings associated with wind-heating; however, in a time of growing concerns over energy security, the importance of wind to meet the heating requirements of communities cannot be overlooked.

  6. Technologies for production of electricity and heat in Sweden. Wind energy in perspective of international development

    Energy Technology Data Exchange (ETDEWEB)

    Clausen, Niels-Erik; Lawaetz, Henrik; Lemming, Joergen; Morthorst, Poul Erik

    2008-12-15

    The development of the wind energy technology has been very successful from the 1970s and up till now. Initially there was a battle between wind turbine concepts, but the commercial winner today is the three-bladed horizontal axis, upwind, electricity producing and grid connected wind turbine with availability on mature markets somewhere around 99%. An important contributor to the growth of the European market for wind energy technology has been EU framework legislation combined with legislation at the national level. The binding target for renewable energy in Sweden is proposed to be 49% of the final energy consumption in 2020 compared to 39.8% in 2005. To stimulate the development of wind energy and to promote a specific national goals Sweden is mainly using an electricity certificate system. The target is to increase the production of electricity from renewable sources by 17 TWh in 2016, relative to corresponding production in 2002. There is not at specific target for the use of wind energy. A future energy system that includes a high proportion of wind energy will be expected to meet the same requirements for security of supply and economic efficiency as the energy systems of today. The variability of wind power create a specific challenges for the future energy systems compared to those of today. The economics of wind power depends mainly of investment cost, operation and maintenance costs, electricity production and turbine lifetime. An average turbine installed in Europe has a total investment cost of 1.230 Euro/kW with a typically variation from approximately 1000 Euro/kW to approximately 1400 Euro/kW. The calculated costs per kWh wind generated power range from approximately 7-10 cEuro/kWh at sites with low average wind speeds to approximately 5-6.5 cEuro/kWh at good coastal positions, with an average of approximately 7cEuro/kWh at a medium wind site. Offshore costs are largely dependent on weather and wave conditions, water depth, and distance to the

  7. Bulk electric system reliability evaluation incorporating wind power and demand side management

    Science.gov (United States)

    Huang, Dange

    Electric power systems are experiencing dramatic changes with respect to structure, operation and regulation and are facing increasing pressure due to environmental and societal constraints. Bulk electric system reliability is an important consideration in power system planning, design and operation particularly in the new competitive environment. A wide range of methods have been developed to perform bulk electric system reliability evaluation. Theoretically, sequential Monte Carlo simulation can include all aspects and contingencies in a power system and can be used to produce an informative set of reliability indices. It has become a practical and viable tool for large system reliability assessment technique due to the development of computing power and is used in the studies described in this thesis. The well-being approach used in this research provides the opportunity to integrate an accepted deterministic criterion into a probabilistic framework. This research work includes the investigation of important factors that impact bulk electric system adequacy evaluation and security constrained adequacy assessment using the well-being analysis framework. Load forecast uncertainty is an important consideration in an electrical power system. This research includes load forecast uncertainty considerations in bulk electric system reliability assessment and the effects on system, load point and well-being indices and reliability index probability distributions are examined. There has been increasing worldwide interest in the utilization of wind power as a renewable energy source over the last two decades due to enhanced public awareness of the environment. Increasing penetration of wind power has significant impacts on power system reliability, and security analyses become more uncertain due to the unpredictable nature of wind power. The effects of wind power additions in generating and bulk electric system reliability assessment considering site wind speed

  8. Energy-Efficiency Policy Opportunities for Electric Motor-Driven Systems

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2011-07-01

    This publication is the first global analysis of energy consumption and energy efficiency potential of EMDS (electric motor- driven system). The electric motors and systems they drive are the largest single electricity end use, accounting for more than 40% of global electricity consumption. Huge energy efficiency potential was found untapped in EMDS - around 25% of EMDS electricity use could be saved cost-effectively, reducing total global electricity demand by about 10%. However, the energy efficiency of EMDS has been relatively neglected in comparison with other sustainable energy opportunities. It is crucial to scale up the operations and resources committed to realizing the vast savings potential of optimized EMDS. This paper proposes a comprehensive package of policy recommendations to help governments realize the potential for energy savings in EMDS.

  9. Submerged electricity generation plane with marine current-driven motors

    Science.gov (United States)

    Dehlsen, James G.P.; Dehlsen, James B.; Fleming, Alexander

    2014-07-01

    An underwater apparatus for generating electric power from ocean currents and deep water tides. A submersible platform including two or more power pods, each having a rotor with fixed-pitch blades, with drivetrains housed in pressure vessels that are connected by a transverse structure providing buoyancy, which can be a wing depressor, hydrofoil, truss, or faired tube. The platform is connected to anchors on the seafloor by forward mooring lines and a vertical mooring line that restricts the depth of the device in the water column. The platform operates using passive, rather than active, depth control. The wing depressor, along with rotor drag loads, ensures the platform seeks the desired operational current velocity. The rotors are directly coupled to a hydraulic pump that drives at least one constant-speed hydraulic-motor generator set and enables hydraulic braking. A fluidic bearing decouples non-torque rotor loads to the main shaft driving the hydraulic pumps.

  10. Evaluation of the Influence of Wind-Driven Rain on Moisture in Cellular Concrete Wall Boards

    Directory of Open Access Journals (Sweden)

    Alsabry A.

    2017-08-01

    Full Text Available The non-stationary moisture level of a cellular concrete wall board in a heated utility building located in the northern part of the town of Brest (Belarus, depending on the climatic influence, was assessed in this work. The results were obtained both in a calculation experiment and a physical test. It was observed that the main reason for the high moisture levels in cellular concrete is wind-driven rain intensifying the process of free capillary moisture transfer. A comparative analysis of the results of the physical test and the calculation experiment showed that the THSS software elaborated by the authors was able to predict the actual moisture levels of the shielding structure under study accurately enough when precise data concerning the thermal and physical characteristics of the materials as well as the occurring climatic influences were submitted.

  11. Evaluation of the Influence of Wind-Driven Rain on Moisture in Cellular Concrete Wall Boards

    Science.gov (United States)

    Alsabry, A.; Nikitsin, V. I.; Kofanov, V. A.; Backiel-Brzozowska, B.

    2017-08-01

    The non-stationary moisture level of a cellular concrete wall board in a heated utility building located in the northern part of the town of Brest (Belarus), depending on the climatic influence, was assessed in this work. The results were obtained both in a calculation experiment and a physical test. It was observed that the main reason for the high moisture levels in cellular concrete is wind-driven rain intensifying the process of free capillary moisture transfer. A comparative analysis of the results of the physical test and the calculation experiment showed that the THSS software elaborated by the authors was able to predict the actual moisture levels of the shielding structure under study accurately enough when precise data concerning the thermal and physical characteristics of the materials as well as the occurring climatic influences were submitted.

  12. Application of order cyclostationary demodulation to damage detection in a direct-driven wind turbine bearing

    Science.gov (United States)

    Liu, Xiaofeng; Bo, Lin; Peng, Chang

    2014-02-01

    This paper presents a method of fault detection and isolation for a direct-driven wind turbine (DWT) bearing. Computed order tracking is employed to convert the non-stationary envelope signal in the time domain into a quasi-stationary signal in the angular domain by even-angle resampling. Cyclostationary demodulation is then utilized to expose the orders related to fault characteristics in the demodulation spectrum. In order to realize the automatic fault diagnosis and emit a stable alarm about bearing damage, the peak value of the demodulation spectrum is scaled and compared to a defined threshold. The significant advantage of the proposed method is the implementation of an automatic algorithm for DWT bearing diagnostics under randomly varying speed and highly alternating load. Practical applications are provided to show that the proposed approach is able to achieve reliable failure warning in the bearing condition monitoring of a DWT.

  13. Conjectures Concerning Planetary Deuterium Enrichment from Solar Wind or Galactic Clouds Driven by Planetary Magnetic Fields

    Science.gov (United States)

    Arias, F. J.

    2017-09-01

    In this poster, it is conjectured (and theoretically discussed) the possibility of planetary deuterium enrichment contribution in the past driven by planetary magnetic fields and external sources as solar winds or galactic clouds. The mechanism is interesting because: 1) is in clear contrast with current mechanism where planets and bodies are enriched with deuterium by preferential escape of ordinary hydrogen. 2) is linking deuterium enrichment with body magnetic fields, and then observed deuterium enrichment can be a hint that in the past there was magnetic activity in the body 3) open the possibility that geological records can be find with abrupt increase of deuterium and then the possible transit of the solar system crossing galactic clouds.

  14. A Data-Driven Diagnostic Framework for Wind Turbine Structures: A Holistic Approach.

    Science.gov (United States)

    Bogoevska, Simona; Spiridonakos, Minas; Chatzi, Eleni; Dumova-Jovanoska, Elena; Höffer, Rudiger

    2017-03-30

    The complex dynamics of operational wind turbine (WT) structures challenges the applicability of existing structural health monitoring (SHM) strategies for condition assessment. At the center of Europe's renewable energy strategic planning, WT systems call for implementation of strategies that may describe the WT behavior in its complete operational spectrum. The framework proposed in this paper relies on the symbiotic treatment of acting environmental/operational variables and the monitored vibration response of the structure. The approach aims at accurate simulation of the temporal variability characterizing the WT dynamics, and subsequently at the tracking of the evolution of this variability in a longer-term horizon. The bi-component analysis tool is applied on long-term data, collected as part of continuous monitoring campaigns on two actual operating WT structures located in different sites in Germany. The obtained data-driven structural models verify the potential of the proposed strategy for development of an automated SHM diagnostic tool.

  15. Influence of input data on airflow network accuracy in residential buildings with natural wind- and stack-driven ventilation

    DEFF Research Database (Denmark)

    Arendt, Krzysztof; Krzaczek, Marek; Tejchman, Jacek

    2017-01-01

    The airflow network (AFN) modeling approach provides an attractive balance between the accuracy and computational demand for naturally ventilated buildings. Its accuracy depends on input parameters such as wind pressure and opening discharge coefficients. In most cases, these parameters...... is still poor. In this paper, the influence of wind pressure data on the accuracy of a coupled AFN-BES model for a real building with natural wind- and stack-driven ventilation was analyzed. The results of 8 computation cases with different wind pressure data from secondary sources were compared...... are obtained from secondary sources which are solely representative for very simplified buildings, i.e. for buildings without facade details. Although studies comparing wind pressure coefficients or discharge coefficients from different sources exist, the knowledge regarding the effect of input data on AFN...

  16. Impact of Wind Driven Pond Expansion on Landloss in the Mississippi River Delta Plain

    Science.gov (United States)

    Ortiz, A. C.; Edmonds, D. A.

    2016-12-01

    Wetlands of the Mississippi River Delta Plain (MRDP) have been disappearing over the past century due to decreased sediment load, anthropogenic management, increased subsidence, and accelerating eustatic sea-level rise. These effects can cause landloss by submergence of the wetland surface or by lateral erosion of the edges. Given the economic and ecological importance of the MRDP, it is vital to quantify the relative contribution of each process. Using three year Landsat composites, we created a 33 year time series of land-water maps for the Atchafalaya-Vermillion, Terrebonne, and Barataria watersheds. These three watersheds represent the range of MRDP conditions and anthropogenic impacts. The composite images are the per-pixel 50% average across all bands for all non-cloudy pixels over three years to minimize effects of poor image quality, limited number of images, and bias from floating vegetation on water bodies. The land-water binary images are created using dynamic thresholding based off modified normal difference water index with all land and water bodies smaller than 8 pixels (7,200 m2) removed. On each binary composite image we select and track the 444 ponds that: 1) appear in every composite; 2) have a simple shape; and 3) are expanding. Remarkably, in all basins these ponds show expansion in the south-south-west direction. In particular, Atchafalaya-Vermillion shows expansion to the SSW, WSW, and NNW while Barataria shows expansion in WSW and NNW. We hypothesize that this expansion is caused by enhanced edge erosion from wind-driven waves because pond expansion directions are consistent with wind direction data. The large wind events (10-15 m/s) come from the north and the most frequent wind events (5-10 m/s) come from the south and east. Furthermore, we show a correlation between pond size and magnitude of expansion, which is also consistent with models for pond expansion by wind-waves. We suggest that land loss by edge erosion on the MRDP may be more

  17. Wind-driven circulation patterns in a shallow estuarine lake: St Lucia, South Africa

    Science.gov (United States)

    Schoen, Julia H.; Stretch, Derek D.; Tirok, Katrin

    2014-06-01

    The spatiotemporal structure of wind-driven circulation patterns and associated water exchanges or residence times can drive important bio-hydrodynamic interactions in shallow lakes and estuaries. The St Lucia estuarine lake in South Africa is an example of such a system. It is a UNESCO World Heritage Site and RAMSAR wetland of international importance but no detailed research on its circulation patterns has previously been undertaken. In this study, a hydrodynamic model was used to investigate the structure of these circulations to provide insights into their role in transport and water exchange processes. A strong diurnal temporal pattern of wind speeds, together with directional switching between two dominant directions, drives intermittent water exchanges and mixing between the lake basins. “High speed flows in shallow nearshore areas with slower upwind counter-flows in deeper areas, linked by circulatory gyres, are key features of the circulation”. These patterns are strongly influenced by the complex geometry of St Lucia and constrictions in the system. Water exchange time scales are non-homogeneous with some basin extremities having relatively long residence times. The influence of the circulation patterns on biological processes is discussed.

  18. Impact of (α, n) reactions on weak r-process in neutrino-driven winds

    Science.gov (United States)

    Bliss, J.; Arcones, A.; Montes, F.; Pereira, J.

    2017-05-01

    After a successful core-collapse supernova, a neutrino-driven wind develops where it is possible to synthesize lighter heavy elements (30 critical to redistribute the matter and allow it to move from light to heavy elements after nuclear statistical equilibrium freezes out. In this first sensitivity study, we vary all (α, n) reactions by given constant factors which are justified based on the uncertainties of the statistical model and its nuclear physics input, mainly alpha optical potentials for weak r-process conditions. Our results show that (α, n) rate uncertainties are indeed crucial to predict abundances. Therefore, further studies will follow to identify individual critical reactions. Since the nucleosynthesis path is close to stability, these reactions can be measured in the near future. Since much of the other nuclear data for the weak r-process are known, the reduction in nuclear physics uncertainties provided by these experiments will allow astronomical observations to directly constrain the astronomical conditions in the wind.

  19. Sliding mode direct power control of RSC for DFIGs driven by variable speed wind turbines

    Directory of Open Access Journals (Sweden)

    E.G. Shehata

    2015-12-01

    Full Text Available In spite of its several advantages, a classic direct power control (DPC of doubly fed induction generators (DFIGs driven by variable speed wind turbines has some drawbacks. In this paper, a simple and robust total sliding mode controller (TSMC is designed to improve the classical DPC performance without complicating the overall scheme. The TSMC is designed to regulate the DFIG stator active and reactive powers. Two integral switching functions are selected for describing the switching surfaces of the active and reactive powers. Reaching phase stability problem of the classical sliding mode controller is avoided in the proposed TSMC. Neither current control loops nor accurate values of machine parameters are required in the proposed scheme. In addition, axes transformation of the stator voltage and current are eliminated. The grid side converter is controlled based on DPC principle to regulate both DC-link voltage and total reactive power. The feasibility of the proposed DPC scheme is validated through simulation studies on a 1.5 MW wind power generation system. The performance of the proposed and conventional DPC schemes is compared under different operating conditions.

  20. Forecasting and decision-making in electricity markets with focus on wind energy

    DEFF Research Database (Denmark)

    Jónsson, Tryggvi

    accounting for this effect in models for day-ahead forecasting of the prices are also presented in the thesis. Prompted by the volatile behaviour of electricity markets, considerable focus has been on time-varying and robust parameter estimates. The models derived are all based on well know methods from......This thesis deals with analysis, forecasting and decision making in liberalised electricity markets. Particular focus is on wind power, its interaction with the market and the daily decision making of wind power generators. Among recently emerged renewable energy generation technologies, wind power...... by these different characteristics. The thesis presents analyses of how this impact is realised in markets significantly penetrated by wind power. Due to its representation by forecasts in the supply curve, such predictions are used to describe their non-linear influence on the market prices. Methods adequately...

  1. Effects of interruptible load program on equilibrium outcomes of electricity markets with wind power

    Energy Technology Data Exchange (ETDEWEB)

    An, Xuena; Zhang, Shaohua; Li, Xue [Shanghai Univ. (China). Key Lab. of Power Station Automation Technology

    2013-07-01

    High wind power penetration presents a lot of challenges to the flexibility and reliability of power system operation. In this environment, various demand response (DR) programs have got much attention. As an effective measure of demand response programs, interruptible load (IL) programs have been widely used in electricity markets. This paper addresses the problem of impacts of the IL programs on the equilibrium outcomes of electricity wholesale markets with wind power. A Cournot equilibrium model of wholesale markets with wind power is presented, in which IL programs is included by a market demand model. The introduction of the IL programs leads to a non-smooth equilibrium problem. To solve this equilibrium problem, a novel solution method is proposed. Numerical examples show that IL programs can lower market price and its volatility significantly, facilitate the integration of wind power.

  2. Electrically driven single-photon emission from an isolated single molecule.

    Science.gov (United States)

    Zhang, Li; Yu, Yun-Jie; Chen, Liu-Guo; Luo, Yang; Yang, Ben; Kong, Fan-Fang; Chen, Gong; Zhang, Yang; Zhang, Qiang; Luo, Yi; Yang, Jin-Long; Dong, Zhen-Chao; Hou, J G

    2017-09-18

    Electrically driven molecular light emitters are considered to be one of the promising candidates as single-photon sources. However, it is yet to be demonstrated that electrically driven single-photon emission can indeed be generated from an isolated single molecule notwithstanding fluorescence quenching and technical challenges. Here, we report such electrically driven single-photon emission from a well-defined single molecule located inside a precisely controlled nanocavity in a scanning tunneling microscope. The effective quenching suppression and nanocavity plasmonic enhancement allow us to achieve intense and stable single-molecule electroluminescence. Second-order photon correlation measurements reveal an evident photon antibunching dip with the single-photon purity down to g (2) (0) = 0.09, unambiguously confirming the single-photon emission nature of the single-molecule electroluminescence. Furthermore, we demonstrate an ultrahigh-density array of identical single-photon emitters.Molecular emitters offer a promising solution for single-photon generation. Here, by exploiting electronic decoupling by an ultrathin dielectric spacer and emission enhancement by a resonant plasmonic nanocavity, the authors demonstrate electrically driven single-photon emission from a single molecule.

  3. RECONNECTION-DRIVEN CORONAL-HOLE JETS WITH GRAVITY AND SOLAR WIND

    Energy Technology Data Exchange (ETDEWEB)

    Karpen, J. T.; DeVore, C. R.; Antiochos, S. K. [Heliophysics Science Division, NASA Goddard Space Flight Center, Greenbelt MD 20771 (United States); Pariat, E. [LESIA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Université, UPMC Univ. Paris 06, Univ. Paris Diderot, Sorbonne Paris Cité, 5 place Jules Janssen, F-92195 Meudon (France)

    2017-01-01

    Coronal-hole jets occur ubiquitously in the Sun's coronal holes, at EUV and X-ray bright points associated with intrusions of minority magnetic polarity. The embedded-bipole model for these jets posits that they are driven by explosive, fast reconnection between the stressed closed field of the embedded bipole and the open field of the surrounding coronal hole. Previous numerical studies in Cartesian geometry, assuming uniform ambient magnetic field and plasma while neglecting gravity and solar wind, demonstrated that the model is robust and can produce jet-like events in simple configurations. We have extended these investigations by including spherical geometry, gravity, and solar wind in a nonuniform, coronal hole-like ambient atmosphere. Our simulations confirm that the jet is initiated by the onset of a kink-like instability of the internal closed field, which induces a burst of reconnection between the closed and external open field, launching a helical jet. Our new results demonstrate that the jet propagation is sustained through the outer corona, in the form of a traveling nonlinear Alfvén wave front trailed by slower-moving plasma density enhancements that are compressed and accelerated by the wave. This finding agrees well with observations of white-light coronal-hole jets, and can explain microstreams and torsional Alfvén waves detected in situ in the solar wind. We also use our numerical results to deduce scaling relationships between properties of the coronal source region and the characteristics of the resulting jet, which can be tested against observations.

  4. Reconnection-Driven Coronal-Hole Jets with Gravity and Solar Wind

    Science.gov (United States)

    Karpen, J. T.; Devore, C. R.; Antiochos, S. K.; Pariat, E.

    2017-01-01

    Coronal-hole jets occur ubiquitously in the Sun's coronal holes, at EUV and X-ray bright points associated with intrusions of minority magnetic polarity. The embedded-bipole model for these jets posits that they are driven by explosive, fast reconnection between the stressed closed field of the embedded bipole and the open field of the surrounding coronal hole. Previous numerical studies in Cartesian geometry, assuming uniform ambient magnetic field and plasma while neglecting gravity and solar wind, demonstrated that the model is robust and can produce jet-like events in simple configurations. We have extended these investigations by including spherical geometry,gravity, and solar wind in a nonuniform, coronal hole-like ambient atmosphere. Our simulations confirm that the jet is initiated by the onset of a kink-like instability of the internal closed field, which induces a burst of reconnection between the closed and external open field, launching a helical jet. Our new results demonstrate that the jet propagation is sustained through the outer corona, in the form of a traveling nonlinear Alfven wave front trailed by slower-moving plasma density enhancements that are compressed and accelerated by the wave. This finding agrees well with observations of white-light coronal-hole jets, and can explain microstreams and torsional Alfven waves detected in situ in the solar wind. We also use our numerical results to deduce scaling relationships between properties of the coronal source region and the characteristics of the resulting jet, which can be tested against observations.

  5. Solar r-process-constrained actinide production in neutrino-driven winds of supernovae

    Science.gov (United States)

    Goriely, S.; Janka, H.-Th.

    2016-07-01

    Long-lived radioactive nuclei play an important role as nucleo-cosmochronometers and as cosmic tracers of nucleosynthetic source activity. In particular, nuclei in the actinide region like thorium, uranium, and plutonium can testify to the enrichment of an environment by the still enigmatic astrophysical sources that are responsible for the production of neutron-rich nuclei by the rapid neutron-capture process (r-process). Supernovae and merging neutron-star (NS) or NS-black hole binaries are considered as most likely sources of the r-nuclei. But arguments in favour of one or the other or both are indirect and make use of assumptions; they are based on theoretical models with remaining simplifications and shortcomings. An unambiguous observational determination of a production event is still missing. In order to facilitate searches in this direction, e.g. by looking for radioactive tracers in stellar envelopes, the interstellar medium or terrestrial reservoirs, we provide improved theoretical estimates and corresponding uncertainty ranges for the actinide production (232Th, 235, 236, 238U, 237Np, 244Pu, and 247Cm) in neutrino-driven winds of core-collapse supernovae. Since state-of-the-art supernova models do not yield r-process viable conditions - but still lack, for example, the effects of strong magnetic fields - we base our investigation on a simple analytical, Newtonian, adiabatic and steady-state wind model and consider the superposition of a large number of contributing components, whose nucleosynthesis-relevant parameters (mass weight, entropy, expansion time-scale, and neutron excess) are constrained by the assumption that the integrated wind nucleosynthesis closely reproduces the Solar system distribution of r-process elements. We also test the influence of uncertain nuclear physics.

  6. Electric vehicles to support large wind power penetration in future danish power systems

    DEFF Research Database (Denmark)

    Pillai, Jayakrishnan Radhakrishna; Bak-Jensen, Birgitte; Thøgersen, Paul

    2012-01-01

    Electric Vehicles (EVs) could play major role in the future intelligent grids to support a large penetration of renewable energy in Denmark, especially electricity production from wind turbines. The future power systems aims to phase-out big conventional fossil-fueled generators with large number...... and generation. This paper analyses power balancing support services from EVs and the feasible levels of electric vehicle integration possible to provide grid ancillary services in Danish power systems. This evaluation is conducted on typical wind dominated distribution and transmission networks in Denmark....... The analyses show that EV integration of around 10% is capable of providing sufficient grid regulation services in Danish power systems to support wind power penetration of around 50% in Denmark. The aggregated EV penetration levels quantified on system levels are validated with impact assessment studies...

  7. Electricity Generation and Energy Cost Estimation of Large-Scale Wind Turbines in Jarandagh, Iran

    Directory of Open Access Journals (Sweden)

    Kasra Mohammadi

    2014-01-01

    Full Text Available Currently, wind energy utilization is being continuously growing so that it is regarded as a large contender of conventional fossil fuels. This study aimed at evaluating the feasibility of electricity generation using wind energy in Jarandagh situated in Qazvin Province in north-west part of Iran. The potential of wind energy in Jarandagh was investigated by analyzing the measured wind speed data between 2008 and 2009 at 40 m height. The electricity production and economic evaluation of four large-scale wind turbine models for operation at 70 m height were examined. The results showed that Jarandagh enjoys excellent potential for wind energy exploitation in 8 months of the year. The monthly wind power at 70 m height was in the range of 450.28–1661.62 W/m2, and also the annual wind power was 754.40 W/m2. The highest capacity factor was obtained using Suzlon S66/1.25 MW turbine model, while, in terms of electricity generation, Repower MM82/2.05 MW model showed the best performance with total annual energy output of 5705 MWh. The energy cost estimation results convincingly demonstrated that investing on wind farm construction using all nominated turbines is economically feasible and, among all turbines, Suzlon S66/1.25 MW model with energy cost of 0.0357 $/kWh is a better option.

  8. Impact of neutrino flavor oscillations on the neutrino-driven wind nucleosynthesis of an electron-capture supernova

    NARCIS (Netherlands)

    Pllumbi, E.; Tamborra, I.; Wanajo, S.; Janka, H.-T.; Hüdepohl, L.

    2015-01-01

    Neutrino oscillations, especially to light sterile states, can affect nucleosynthesis yields because of their possible feedback effect on the electron fraction (Ye). For the first time, we perform nucleosynthesis calculations for neutrino-driven wind trajectories from the neutrino-cooling phase of

  9. Simulation of barotropic wind-driven circulation in tbe Bay of Bengal and Andaman Sea during premonsoon and postmonsoon seasons

    Digital Repository Service at National Institute of Oceanography (India)

    Unnikrishnan, A.S.; Bahulayan, N.

    Two-dimensional vertically integrated model has been used to simulate depth-mean wind-driven circulation during premonsoon and postmonsoon seasons in the upper layers of the Bay of Bengal and Andaman Sea. The model is integrated for 365 d, forcEd...

  10. Interaction of additive noise and nonlinear dynamics in the double-gyre wind-driven ocean circulation

    NARCIS (Netherlands)

    Sapsis, T.; Dijkstra, H.A.|info:eu-repo/dai/nl/073504467

    2013-01-01

    In this paper the authors study the interactions of additive noise and nonlinear dynamics in a quasi-geostrophicmodel of the double-gyre wind-driven ocean circulation. The recently developed framework of dynamically orthogonal field theory is used to determine the statistics of the flows that arise

  11. Microbial ecology meets electrochemistry: electricity-driven and driving communities.

    Science.gov (United States)

    Rabaey, Korneel; Rodríguez, Jorge; Blackall, Linda L; Keller, Jurg; Gross, Pamela; Batstone, Damien; Verstraete, Willy; Nealson, Kenneth H

    2007-05-01

    Bio-electrochemical systems (BESs) have recently emerged as an exciting technology. In a BES, bacteria interact with electrodes using electrons, which are either removed or supplied through an electrical circuit. The most-described type of BES is microbial fuel cells (MFCs), in which useful power is generated from electron donors as, for example, present in wastewater. This form of charge transport, known as extracellular electron transfer, was previously extensively described with respect to metals such as iron and manganese. The importance of these interactions in global biogeochemical cycles is essentially undisputed. A wide variety of bacteria can participate in extracellular electron transfer, and this phenomenon is far more widespread than previously thought. The use of BESs in diverse research projects is helping elucidate the mechanism by which bacteria shuttle electrons externally. New forms of interactions between bacteria have been discovered demonstrating how multiple populations within microbial communities can co-operate to achieve energy generation. New environmental processes that were difficult to observe or study previously can now be simulated and improved via BESs. Whereas pure culture studies make up the majority of the studies performed thus far, even greater contributions of BESs are expected to occur in natural environments and with mixed microbial communities. Owing to their versatility, unmatched level of control and capacity to sustain novel processes, BESs might well serve as the foundation of a new environmental biotechnology. While highlighting some of the major breakthroughs and addressing only recently obtained data, this review points out that despite rapid progress, many questions remain unanswered.

  12. The contribution of wind energy to electric power generation; Der Beitrag der Windenergie zur Stromerzeugung

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-07-01

    The conference discussed the following five subjects: (1) Status and perspectives of wind power in Germany and Japan; (2) Grid connection of wind power systems; (3) Wind power and electric power supply; (4) Future fields of application, technical perspectives; (5) Panel discussion. [German] Der Tagungsband beinhaltet Beitraege in fuenf Bloecken, die die folgenden Ueberschriften haben: (1) Stand und Perspektiven der Windenergienutzung in Deutschland und Japan; (2) Netzintegration von Windenergieanlagen; (3) Windenergie in der elektrischen Energieversorgung; (4) zukuenftige Anwendungsfelder, technische Perspektiven sowie (5) Paneldiskussion. (AKF)

  13. Electric Vehicles for Improved Operation of Power Systems with High Wind Power Penetration

    DEFF Research Database (Denmark)

    Larsen, Esben; Chandrashekhara, Divya K; Østergaard, Jacob

    2008-01-01

    vehicles (EDV) as flexible loads can improve the system operation. Bidirectional power exchange through batteries (vehicle to grid) can be seen as a storage system in the grid. An analysis of possible economical incentives for the vehicle owners will be shown. By control of EDV charging through a price......In a power system with a high share of wind energy the wind fluctuation causes a variation in the power generation, which must be compensated from other sources. The situation in Denmark with a penetration of more than 20% wind in yearly average is presented. The introduction of electric drive...

  14. [Hygienic problems in the location of modern wind electric power stations in their design].

    Science.gov (United States)

    Kireeva, I S; Makhniuk, V M; Akimenko, V Ia; Dumanskiĭ, Iu D; Semashko, P V

    2013-01-01

    Hygienic aspects of the placement of wind power plants (WPP) in connection with the intensive development of wind power and the lack of systematic information on their effects of the environment and living conditions of the population are becoming more actual. In the article there are considered results of the sanitary-epidemiological expertise of the construction project of three modern large wind farm (the South - Ukrainian, Tiligulskaya and Pokrovskaya) with a total capacity offrom 180 to 500 MW of wind farms with 2.3 MW power generators of wind turbines. It is shown that in the process of wind farm construction a contamination of the environment (air soil, ground water) may take place due to the working of construction equipment and vehicle, excavation, welding and other operations, in the exploitation of wind farm there can be created elevated levels of acoustic and electromagnetic pollution in the neighborhood and emergencies with the destruction of WPP in adverse weather conditions. Based on the calculations presented in the projects, and the analysis of data on the impact offoreign windfarm on the environment it was found that the limiting factor of the influence is the wind farm noise pollution in the audio frequency range that extends beyond the territory of wind fields, electromagnetic radiation is recorded within the hygienic standards and below only in the immediate vicinity of its sources (electrical equipment and power lines). For considered modern wind farms there was grounded sanitary protective zone with dimensions of 700 mfrom the outermost wind turbines by the noise and it was recommended compliance distance of200 mfrom the wind turbine to limit any activity and people staying in times of possible emergency situations in adverse weather conditions.

  15. Reliability Assessment of Offshore Wind Turbines Considering Faults of Electrical / Mechanical Components

    DEFF Research Database (Denmark)

    Kostandyan, Erik; Sørensen, John Dalsgaard

    2013-01-01

    For offshore wind turbines, the cost contribution to Cost of Energy from inspections and Operation & Maintenance can be substantial, and can be expected to increase when wind farms are placed at deeper water depths, further from the coast and in more harsh environments. Estimates of the reliability...... of structural, mechanical and electrical components are important, in order to optimally plan Operation & Maintenance strategies. A general model for reliability estimation of structural, mechanical or electrical components is described. For a representative failure mode a corresponding limit state...

  16. Effects of internal loading on phosphorus distribution in the Taihu Lake driven by wind waves and lake currents.

    Science.gov (United States)

    Huang, Lei; Fang, Hongwei; He, Guojian; Jiang, Helong; Wang, Changhui

    2016-12-01

    Wind-driven sediment resuspension exerts significant effects on the P behavior in shallow lake ecosystems. In this study, a comprehensive dynamic phosphorus (P) model that integrates hydrodynamic, wind wave and sediment transport is proposed to assess the importance of internal P cycling due to sediment resuspension on water column P levels. The primary contribution of the model is detailed modeling and rigorous coupling of sediment and P dynamics. The proposed model is applied to predict the P behavior in the shallow Taihu Lake, which is the third largest lake in China, and quantitatively estimate the effects of wind waves and lake currents on P release and distribution. Both the prevailing southeast winds in summer and northwest winds in winter are applied for the simulation, and different wind speeds of 5 m/s and 10 m/s are also considered. Results show that sediment resuspension and the resulting P release have a dominant effect on P levels in Taihu Lake, and likely similar shallow lakes. Wind-driven waves at higher wind speeds significantly enhance sediment resuspension and suspended sediment concentration (SSC). Total P concentration in the water column is also increased but not in proportion to the SSC. The different lake circulations resulting from the different prevailing wind directions also affect the distribution of suspended sediment and P around the lake ultimately influencing where eutrophication is likely to occur. The proposed model demonstrates that internal cycling in the lake is a dominant factor in the lake P and must be considered when trying to manage water quality in this and similar lakes. The model is used to demonstrate the potential effectiveness of remediation of an area where historical releases have led to P accumulation on overall lake quality. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Efficiency evaluation of gas fuelled and electric driven buses in the public transport sector

    Energy Technology Data Exchange (ETDEWEB)

    Aigner, Tobias Alexander

    2013-07-01

    The following report evaluates the efficiency of gas fuelled and electric driven buses in the public transport sector on a theoretical basis. The results indicate that the combination of CHP power plants and electric driven buses reach an overall efficiency of about 51% throughout the production chain (Well-to-Wheel), including heat distribution losses. The overall Well-to-Wheel efficiency for conventional gas turbines without heat recovery decreases to around 28%. For gas fuelled buses the Well-to-Wheel efficiency is about 30%. The Co2-emissions are evaluated based on the example of a #Left Double Quotation Mark#Volvo B10L CNG#Right Double Quotation Mark# gas bus and the electric driven #Left Double Quotation Mark#Eurabus 600#Right Double Quotation Mark#. The low energy consumption of the electric driven bus results in Co2-emissions of only 181.4 g Co2/km (Grid-to-Wheel). Depending on the utilised power plant technology the overall Co2-emissions (Well-to-Wheel) amount to 307.5 g Co2/km for a CHP power plant and 553.5 g Co2/km for a conventional gas turbine. On the other hand, gas fuelled buses emit about 1.25 kg Co2/km (Tank-to-Wheel), which is eightfold the emissions of an electrical bus. The Well-to-Tank emissions further increase to about 1.32 kg Co2/km. The emission calculation is based on real gas consumption data from a Norwegian public transport utility. The results indicate that the combination of CHP plants and electrical buses provide a much higher efficiency while reducing Co2-emissions. (author)

  18. Windonomics. Empirical essays on the economics of wind power in the Nordic electricity market

    Energy Technology Data Exchange (ETDEWEB)

    Mauritzen, Johannes

    2012-07-01

    From the introduction: The following chapters in this dissertation take up three topics surrounding the interaction of wind power investment in Denmark and the functioning of the deregulated Nordic electricity market. The first two chapters take up the issue of how wind power a affects prices in the deregulated market. I find that electricity price variation in the spot market is lower in days with more wind power. In the following chapter I extend this analysis to see how wind power in Denmark affects prices in neighbouring hydro power dominated Norway. I find that wind power affects the magnitude of trade between the countries asymmetrically - dependent on the net direction of trade. I also find that wind power has a slight but statistically significant negative effect on prices in Norway, likely due to a slackening of hydro power producers supply constraints. The last chapter starts with the observation that most turbines are scrapped in order to make room for a newer turbine. An opportunity cost that comes from the interaction of scarce land resources, technological change and government policy is then a dominant reason for the scrapping of wind turbines. This leads to the implication that turbines located on windier, better situated land have a higher risk of being scrapped. Policy is also shown to have a strong and in some respects unexpected effect on scrappings. Over the last two decades two major trends have taken place in power markets around the world. The first has been a movement towards market based power systems. Vertically integrated power companies have been split into component generation, transmission and retailing companies. Generation and retailing have been opened to competition. Increasingly, regulated prices and bilateral trade are being replaced by regulated markets that establish prices through auction mechanisms. The second trend has been investment in renewable and intermittent energy sources - notably wind power. What started as

  19. Proactive monitoring of an onshore wind farm through lidar measurements, SCADA data and a data-driven RANS solver

    Science.gov (United States)

    Iungo, Giacomo Valerio; Camarri, Simone; Ciri, Umberto; El-Asha, Said; Leonardi, Stefano; Rotea, Mario A.; Santhanagopalan, Vignesh; Viola, Francesco; Zhan, Lu

    2016-11-01

    Site conditions, such as topography and local climate, as well as wind farm layout strongly affect performance of a wind power plant. Therefore, predictions of wake interactions and their effects on power production still remain a great challenge in wind energy. For this study, an onshore wind turbine array was monitored through lidar measurements, SCADA and met-tower data. Power losses due to wake interactions were estimated to be approximately 4% and 2% of the total power production under stable and convective conditions, respectively. This dataset was then leveraged for the calibration of a data driven RANS (DDRANS) solver, which is a compelling tool for prediction of wind turbine wakes and power production. DDRANS is characterized by a computational cost as low as that for engineering wake models, and adequate accuracy achieved through data-driven tuning of the turbulence closure model. DDRANS is based on a parabolic formulation, axisymmetry and boundary layer approximations, which allow achieving low computational costs. The turbulence closure model consists in a mixing length model, which is optimally calibrated with the experimental dataset. Assessment of DDRANS is then performed through lidar and SCADA data for different atmospheric conditions. This material is based upon work supported by the National Science Foundation under the I/UCRC WindSTAR, NSF Award IIP 1362033.

  20. Electricity power planning in Portugal : the role of wind energy

    OpenAIRE

    Ferreira, Paula Varandas

    2008-01-01

    Tese de Doutoramento em Engenharia Económica - Engenharia Produção e Sistemas Energy decisions play a major role in the achievement of sustainable development and consequently on the economic, environmental and social welfare of future generations. Combining energy efficiency with renewable energy resources constitutes a key strategy for a sustainable future, emphasised in the European and Portuguese policy guidelines. The wind power sector stands out as a fundamental element f...

  1. DESIGN AND DEVELOPMENT OF A 1/3 SCALE VERTICAL AXIS WIND TURBINE FOR ELECTRICAL POWER GENERATION

    Directory of Open Access Journals (Sweden)

    Altab Hossain

    2007-01-01

    Full Text Available This research describes the electrical power generation in Malaysia by the measurement of wind velocity acting on the wind turbine technology. The primary purpose of the measurement over the 1/3 scaled prototype vertical axis wind turbine for the wind velocity is to predict the performance of full scaled H-type vertical axis wind turbine. The electrical power produced by the wind turbine is influenced by its two major part, wind power and belt power transmission system. The blade and the drag area system are used to determine the powers of the wind that can be converted into electric power as well as the belt power transmission system. In this study both wind power and belt power transmission system has been considered. A set of blade and drag devices have been designed for the 1/3 scaled wind turbine at the Thermal Laboratory of Faculty of Engineering, Universiti Industri Selangor (UNISEL. Test has been carried out on the wind turbine with the different wind velocities of 5.89 m/s, 6.08 m/s and 7.02 m/s. From the experiment, the wind power has been calculated as 132.19 W, 145.40 W and 223.80 W. The maximum wind power is considered in the present study.

  2. DESIGN AND DEVELOPMENT OF A 1/3 SCALE VERTICAL AXIS WIND TURBINE FOR ELECTRICAL POWER GENERATION

    Directory of Open Access Journals (Sweden)

    Altab Md. Hossain

    2007-12-01

    Full Text Available This research describes the electrical power generation in Malaysia by the measurement of wind velocity acting on the wind turbine technology. The primary purpose of the measurement over the 1/3 scaled prototype vertical axis wind turbine for the wind velocity is to predict the performance of full scaled H-type vertical axis wind turbine. The electrical power produced by the wind turbine is influenced by its two major part, wind power and belt power transmission system. The blade and the drag area system are used to determine the powers of the wind that can be converted into electric power as well as the belt power transmission system. In this study both wind power and belt power transmission system has been considered. A set of blade and drag devices have been designed for the 1/3 scaled wind turbine at the Thermal Laboratory of Faculty of Engineering, Universiti Industri Selangor (UNISEL. Test has been carried out on the wind turbine with the different wind velocities of 5.89 m/s, 6.08 m/s and 7.02 m/s. From the experiment, the wind power has been calculated as 132.19 W, 145.40 W and 223.80 W. The maximum wind power is considered in the present study.

  3. Study on a hypothetical replacement of nuclear electricity by wind power in Sweden

    Science.gov (United States)

    Wagner, F.; Rachlew, E.

    2016-05-01

    The Swedish electricity supply system benefits strongly from the natural conditions which allow a high share of hydroelectricity. A complete supply is, however, not possible. Up to now, nuclear power is the other workhorse to serve the country with electricity. Thus, electricity production of Sweden is basically CO2 -free and Sweden has reached an environmental status which others in Europe plan to reach in 2050. Furthermore, there is an efficient exchange within the Nordic countries, Nordpol, which can ease possible capacity problems during dry cold years. In this study we investigate to what extent and with what consequences the base load supply of nuclear power can be replaced by intermittent wind power. Such a scenario leads unavoidably to high wind power installations. It is shown that hydroelectricity cannot completely smooth out the fluctuations of wind power and an additional back-up system using fossil fuel is necessary. From the operational dynamics, this system has to be based on gas. The back-up system cannot be replaced by a storage using surplus electricity from wind power. The surplus is too little. To overcome this, further strong extension of wind power is necessary which leads, however, to a reduction of the use of hydroelectricity if the annual consumption is kept constant. In this case one fossil-free energy form is replaced by another, however, more complex one. A mix of wind power at 22.3GW plus a gas based back-up system with 8.6GW producing together 64.8TWh would replace the present infrastructure with 9GW nuclear power producing 63.8TWh electricity. The specific CO2 -emission increases to the double in this case. Pumped storage for the exclusive supply of Sweden does not seem to be a meaningful investment.-1

  4. Application Research on Drag Reduced Conductors for Electric Power Transmission Lines in Strong Wind Areas

    Directory of Open Access Journals (Sweden)

    Li Dong Qing

    2016-01-01

    Full Text Available The breeze vibration duration of conductors is long, the vibration amplitude is strong and the frequency range is wide for electric power transmission lines in strong wind areas, which seriously affects the safe and stable operation of transmission lines. There are two design schemes of conductors which can achieve the purpose of reducing wind-induced disaster. One is enhancing the structural strength of conductors to withstand wind load, but the investment is enormous and the effect is limited. The other is developing drag reduced conductors to reduce wind load by changing conductor structure. This paper started from application feasibility analysis of drag reduced conductors and designed four drag reduced conductors by structure optimization of the conventional aluminium conductor steel reinforced JL/G1A-630/45-45/7, denoted as DFY630/45(45°-R3.5, DFY630/45(60°-R3.5, DFY630/45(45°–R3.2 and DFY630/45(60°-R3.2, respectively. The wind tunnel test was performed and the wind resistance coefficients in unit length of five conductors were compared. Result showed that the wind resistance coefficients in unit length of four drag reduced conductors were obviously lower than that of the conventional conductor. By controlling the manufacturing process, popularization and application of drag reduced conductors for transmission lines in strong wind areas can be realized.

  5. Economic analysis of wind electricity generation in the northern coast of Senegal

    Directory of Open Access Journals (Sweden)

    Ould Bilal B.

    2014-01-01

    Full Text Available The main target of this paper is to determine the seasonal features of the wind speed in the northwestern of Senegal and to assess the cost of annual energy output using wind turbines provided from several manufactures. The wind data used for this study were collected in four sites located in the northwestern coast of Senegal and cover the period of one year. The seasonal mean wind speed and the annual distribution curves were obtained by using the Weibull distribution function. A technical assessment of electricity generation from five big wind turbines which power is between 640 kW and 2000 kW and from six small wind turbines which power is between 250 W and 10 kW were carried out. The results obtained show that the lower cost (0.0265 €/kWh in Sokhar was observed for the wind turbine Ecotècnia 62. The highest cost was 0.5103 €/kWh (in Gandon observed for the technology of Alize. All wind turbines was better suited to the site of Sokhar with the highest capacity factor and the lowest cost of output energy.

  6. Progress in IEC 61400-27. Electrical simulation models for wind power generation

    Energy Technology Data Exchange (ETDEWEB)

    Soerensen, Poul [DTU Wind Energy, Roskilde (Denmark); Andresen, Bjoern; Bech, John [Siemens Wind Power, Brande (Denmark). Electrical Systems and Generators; Fortmann, Jens [REpower Systems AG, Osterroenfeld (Germany). Wind Power Plant; Pourbeik, Pouyan [Electric Power Research Institute, Inc. (EPRI), Knoxville, TN (United States). Grid Operations and Planning

    2012-07-01

    This paper presents the status of the ongoing work in IEC Technical Committee 88 Working Group 27 (TC88 WG27) developing a standard IEC 61400-27 for ''Electrical simulation models for wind power generation''. The purpose of this standardization work is to define generic simulation models for wind turbines (part 1) and wind power plants (part 2), which are intended for short-term power system stability analyses. WG27 submitted the first CD of Part 1 in December 2012. The CD describes generic wind turbine models and a procedure for validation of wind turbine models. The generic model description consists of a general model structure intending to cover existing as well as future types of wind turbines, and specific fundamental frequency positive sequence models for the four wind turbine types which are widely used today. The validation procedure can be applied to the generic models specified in the standard, or to manufacturer specific fundamental frequency models. The paper will provide a general description of the wind turbine models, a more detailed description of type 4 models, a description of the validation procedure and finally a validation example. Part 2 is in an early stage of development. IEC has approved the New Work Item Proposal (NWIP) of part 2, and this work has officially started 1 October 2012. (orig.)

  7. Meeting the Electrical Energy Needs of a Residential Building with a Wind-Photovoltaic Hybrid System

    OpenAIRE

    Mohammad Hosein Mohammadnezami; Mehdi Ali Ehyaei; Marc A. Rosen; Mohammad Hossein Ahmadi

    2015-01-01

    A complete hybrid system including a photovoltaic cell, a wind turbine, and battery is modeled to determine the best approach for sizing the system to meet the electrical energy needs of a residential building. In evaluating system performance, the city of Tehran is used as a case study. Matlab software is used for analyzing the data and optimizing the system for the given application. Further, the cost of the system design is investigated, and shows that the electrical cost of the hybrid sy...

  8. The Relationship Between Electricity Price and Wind Power Generation in Danish Electricity Markets

    DEFF Research Database (Denmark)

    Hu, Weihao; Chen, Zhe; Bak-Jensen, Birgitte

    2010-01-01

    The western Danish power system is currently the grid area in the world that has the largest share of wind power in its generation profiles, with more than 20% of its annual consumption generated by wind turbines. In this paper, the western Danish power system, which may represent the future...

  9. Wind power turbines for electric power generation: state of art; Turbinas eolicas para a geracao de eletricidade: estado da arte

    Energy Technology Data Exchange (ETDEWEB)

    Feitosa, E.A.N. [Pernambuco Univ., Recife, PE (Brazil). Dept. de Engenharia Mecanica

    1990-12-31

    This work presents the state-of-the-art of wind turbines for electric power generation. The emphasis is given to wind turbines connected to the public electricity grid. The following aspects are discussed: aerodynamics, aero elasticity, structural dynamics, control, and economics. (author). 10 refs.

  10. Wind-driven ocean dynamic effects on the contrasting sea-ice trends around West Antarctica

    Science.gov (United States)

    Lee, Sang-Ki; Volkov, Denis; Lopez, Hosmay; Cheon, Woo Geun; Gordon, Arnold; Liu, Yanyun; Wanninkhof, Rik

    2017-04-01

    Since late 1978, Antarctic sea-ice extent in the East Pacific has retreated persistently over the Amundsen and Bellingshausen Seas in warm seasons, but expanded over the Ross and Amundsen Seas in cold seasons, while an almost opposite trend has occurred in the Atlantic over the Weddell Sea. Previous studies have shown that the contrasting sea-ice trends in the East Pacific and Atlantic could be explained by the strengthening Southern Hemisphere (SH) subpolar low over West Antarctica and associated cold- and warm-air advections and sea-ice drift. By using a surface-forced ocean and sea-ice coupled model, we show that regional wind-driven ocean dynamics also played a key role. In the East Pacific, the strengthening SH westerlies in the region enhanced Ekman upwelling of the warm upper Circumpolar Deep Water, which directly contributed to the retreat of sea ice in warm seasons, and increased the northward Ekman transport of cold Antarctic surface water, which supported the expansion of sea ice in cold seasons. In the Atlantic, the northern branch of the Weddell Gyre strengthened due to the poleward shifting SH westerlies in the region. This in turn sharply increased the meridional thermal gradient across it as constrained by the thermal wind balance. Ocean heat budget analysis further suggests that the strengthened northern branch of the Weddell Gyre acted as a barrier against the poleward ocean heat transport, and thus produced anomalous heat divergence within the Weddell Gyre and anomalous heat convergence north of the gyre. The associated cooling within the Weddell Gyre and the warming north of the gyre contributed to the expansion of sea ice in warm seasons and the retreat in cold seasons, respectively.

  11. Wind-driven ocean dynamics impact on the contrasting sea-ice trends around West Antarctica

    Science.gov (United States)

    Lee, Sang-Ki; Volkov, Denis L.; Lopez, Hosmay; Cheon, Woo Geun; Gordon, Arnold L.; Liu, Yanyun; Wanninkhof, Rik

    2017-05-01

    Since late 1978, Antarctic sea-ice extent in the East Pacific has retreated persistently over the Amundsen and Bellingshausen Seas in warm seasons, but expanded over the Ross and Amundsen Seas in cold seasons, while almost opposite seasonal trends have occurred in the Atlantic over the Weddell Sea. By using a surface-forced ocean and sea-ice coupled model, we show that regional wind-driven ocean dynamics played a key role in driving these trends. In the East Pacific, the strengthening Southern Hemisphere (SH) westerlies in the region enhanced the Ekman upwelling of warm upper Circumpolar Deep Water and increased the northward Ekman transport of cold Antarctic surface water. The associated surface ocean warming south of 68°S and the cooling north of 68°S directly contributed to the retreat of sea-ice in warm seasons and the expansion in cold seasons, respectively. In the Atlantic, the poleward shifting SH westerlies in the region strengthened the northern branch of the Weddell Gyre, which in turn increased the meridional thermal gradient across it as constrained by the thermal wind balance. Ocean heat budget analysis further suggests that the strengthened northern branch of the Weddell Gyre acted as a barrier against the poleward ocean heat transport, and thus produced anomalous heat divergence within the Weddell Gyre and anomalous heat convergence north of the gyre. The associated cooling within the Weddell Gyre and the warming north of the gyre contributed to the expansion of sea-ice in warm seasons and the retreat in cold seasons, respectively.

  12. Resilience of electricity grids against transmission line overloads under wind power injection at different nodes.

    Science.gov (United States)

    Schiel, Christoph; Lind, Pedro G; Maass, Philipp

    2017-09-14

    A steadily increasing fraction of renewable energy sources for electricity production requires a better understanding of how stochastic power generation affects the stability of electricity grids. Here, we assess the resilience of an IEEE test grid against single transmission line overloads under wind power injection based on the dc power flow equations and a quasi-static grid response to wind fluctuations. Thereby we focus on the mutual influence of wind power generation at different nodes. We find that overload probabilities vary strongly between different pairs of nodes and become highly affected by spatial correlations of wind fluctuations. An unexpected behaviour is uncovered: for a large number of node pairs, increasing wind power injection at one node can increase the power threshold at the other node with respect to line overloads in the grid. We find that this seemingly paradoxical behaviour is related to the topological distance of the overloaded line from the shortest path connecting the wind nodes. In the considered test grid, it occurs for all node pairs, where the overloaded line belongs to the shortest path.

  13. Trends in Wind Turbine Generators, and the Role of Electrical Steels

    DEFF Research Database (Denmark)

    Henriksen, Matthew Lee; Jensen, Bogi Bech

    2014-01-01

    Designs of permanent magnet synchronous machines suitable for operation as wind turbine generators are presented and discussed. Design differences in machines intended for operation in geared and direct drive systems are illustrated . Special emphasis is given to the effect of varying...... the electrical steel used for stator laminations....

  14. Analysis of variations in electric power produced at Rejsby Hede wind farm

    DEFF Research Database (Denmark)

    Pedersen, Knud Ole Helgesen; Pedersen, Jørgen Kaas

    1998-01-01

    The variations in the electric power output from the wind farm at Rejsby Hede are analysed from field measurements acquired by a PC-based measuring system.The frequency content in the power variations are derived and it is considered whether a realistic sized energy storage device can remove...

  15. Natural Gas, Wind and Nuclear Options for Generating Electricity in a Carbon Constrained World

    NARCIS (Netherlands)

    Kooten, van G.C.

    2012-01-01

    A linear programming model is used to examine the impact of carbon taxes on the optimal generation mix in the Alberta electrical system. The model permits decommissioning of generating assets with high carbon dioxide emissions and investment in new gas-fired, wind and, in some scenarios, nuclear

  16. The role of co-located storage for wind power producers in conventional electricity markets

    KAUST Repository

    Bitar, E.

    2011-06-01

    In this paper we study the problem of optimizing contract offerings for an independent wind power producer (WPP) participating in conventional day-ahead forward electricity markets for energy. As wind power is an inherently variable source of energy and is difficult to predict, we explore the extent to which co-located energy storage can be used to improve expected profit and mitigate the the financial risk associated with shorting on the offered contracts. Using a simple stochastic model for wind power production and a model for the electricity market, we show that the problem of determining optimal contract offerings for a WPP with co-located energy storage can be solved using convex programming.

  17. Review of DC System Technologies for Large Scale Integration of Wind Energy Systems with Electricity Grids

    Directory of Open Access Journals (Sweden)

    Sheng Jie Shao

    2010-06-01

    Full Text Available The ever increasing development and availability of power electronic systems is the underpinning technology that enables large scale integration of wind generation plants with the electricity grid. As the size and power capacity of the wind turbine continues to increase, so is the need to place these significantly large structures at off-shore locations. DC grids and associated power transmission technologies provide opportunities for cost reduction and electricity grid impact minimization as the bulk power is concentrated at single point of entry. As a result, planning, optimization and impact can be studied and carefully controlled minimizing the risk of the investment as well as power system stability issues. This paper discusses the key technologies associated with DC grids for offshore wind farm applications.

  18. Agglomeration of a comprehensive model for the wind-driven sand transport at the Belgian Coast

    Science.gov (United States)

    Strypsteen, Glenn; Rauwoens, Pieter

    2016-04-01

    Although a lot of research has been done in the area of Aeolian transport, it is only during the last years that attention has been drawn to Aeolian transport in coastal areas. In these areas, the physical processes are more complex, due to a large number of transport limiting parameters. In this PhD-project, which is now in its early stage, a model will be developed which relates the wind-driven sand transport at the Belgian coast with physical parameters such as the wind speed, humidity and grain size of the sand, and the slope of beach and dune surface. For the first time, the interaction between beach and dune dynamics is studied at the Belgian coast. The Belgian coastline is only 67km long, but densely populated and therefore subject to coastal protection and safety. The coast mostly consists of sandy beaches and dikes. Although, still 33km of dunes exist, whose dynamics are far less understood. The overall research approach consists of three pathways: (i) field measurements, (ii) physical model tests, and (iii) numerical simulations. Firstly and most importantly, several field campaigns will provide accurate data of meteo-marine conditions, morphology, and sand transport events on a wide beach at the Belgian Coastline. The experimental set-up consists of a monitoring station, which will provide time series of vegetation cover, shoreline position, fetch distances, surficial moisture content, wind speed and direction and transport processes. The horizontal and vertical variability of the event scale Aeolian sand transport is analyzed with 8 MWAC sand traps. Two saltiphones register the intensity and variations of grain impacts over time. Two meteo-masts, each with four anemometers and one wind vane, provide quantitative measurements of the wind flow at different locations on the beach. Surficial moisture is measured with a moisture sensor. The topography measurements are typically done with laser techniques. To start, two sites are selected for measurement

  19. The role of capacitance in a wind-electric water pumping system

    Energy Technology Data Exchange (ETDEWEB)

    Ling, Shitao [West Texas A& M Univ., Canyon, TX (United States); Clark, R.N. [Conservation and Production Research Lab., Bushland, TX (United States)

    1997-12-31

    The development of controllers for wind-electric water pumping systems to enable the use of variable voltage, variable frequency electricity to operate standard AC submersible pump motors has provided a more efficient and flexible water pumping system to replace mechanical windmills. A fixed capacitance added in parallel with the induction motor improves the power factor and starting ability of the pump motor at the lower cut-in frequency. The wind-electric water pumping system developed by USDA-Agricultural Research Service, Bushland, TX, operated well at moderate wind speeds (5-12 m/s), but tended to lose synchronization in winds above 12 m/s, especially if they were gusty. Furling generally did not occur until synchronization had been lost and the winds had to subside before synchronization could be reestablished. The frequency needed to reestablish synchronization was much lower (60-65 Hz) than the frequency where synchronization was lost (70-80 Hz). As a result, the load (motor and pump) stayed off an excessive amount of time thus causing less water to be pumped and producing a low system efficiency. The controller described in this paper dynamically connects additional capacitance of the proper amount at the appropriate time to keep the system synchronized (running at 55 to 60 Hz) and pumping water even when the wind speed exceeds 15 m/s. The system efficiency was improved by reducing the system off-line time and an additional benefit was reducing the noise caused by the high speed blade rotation when the load was off line in high winds.

  20. How to improve the design of the electrical system in future wind power plants

    DEFF Research Database (Denmark)

    Arana, I.; Kocewiak, Lukasz Hubert; Holbøll, J.

    2009-01-01

    This paper presents three topics which are important for better performance of future wind farms. The topics are investigated in three coordinated Ph.D. projects ongoing at the Technical University of Denmark (DTU), Aalborg University (AAU) and DONG Energy. The objective of all projects is to imp...... and wind farm transformers, and to develop a methodology on how to select appropriate equipment for the power system, control system and protection system....... is to improve the understanding of the main electrical components in wind farms, based on available information, measurement data and simulation tools. The aim of these projects is to obtain validated models of wind turbine (WT) generators, WT converters, WT transformers, submarine cables, circuit breakers...

  1. Optimization of Electrical System for Offshore Wind Farms via a Genetic Algorithm Approach

    DEFF Research Database (Denmark)

    Zhao, Menghua

    ). This platform is based on a knowledge database, and composed of several functional modules such as cost calculation, reliability evaluation, losses calculation, AC-DC integrated load flow algorithm etc. All these modules are based on a spreadsheet database which provides an interface for users to input...... of a grid-connected wind farm; 2) the second one is the optimization of electrical system for offshore wind farms (OES-OWF). The capacity of a grid connected wind farm is limited by the transfer capability of the grid system, where the thermal limit of the transmission lines, the voltage stability...... losses and power generation. This work proposes a serial AC-DC integrated load flow algorithm for variable speed offshore wind farms (VSOWF). The model of DC/DC converters is proposed and integrated into the basic DC load flow algorithm by modifying the Jacobian matrix. Two iterative methods are proposed...

  2. Deformation-driven electrical transport in amorphous TiO2 nanotubes

    Science.gov (United States)

    Asthana, A.; Shokuhfar, T.; Gao, Q.; Heiden, P. A.; Yassar, R. S.

    2012-10-01

    A series of in situ transmission electron microscopy combined with scanning tunneling microscopy measurements were carried out to investigate the effect of mechanical deformation on the electrical transport properties of amorphous TiO2 nanotubes. Under no mechanical straining, it was found that the TiO2 nanotubes behave as electrical insulators. However, the nanotubes show semiconducting behavior under a highly deformed state. On the basis of a metal-semiconductor-metal model, it was suggested that in-shell defects, surface defect-driven conduction modes, are responsible for the appearance of the semiconducting behavior.

  3. Wind-Electric Power Potential Assessment for Three Locations in East Java-Indonesia

    Directory of Open Access Journals (Sweden)

    Ali Musyafa

    2011-08-01

    Full Text Available This paper reports our effort to asses wind energy potentials for three locations in East Java. We used wind speed data over a period of almost 3 years, i.e. in period of June 2006 – August 2008. Data were taken from direct measurement in locations in East Java Province, i.e. Sampang (Madura, Juanda (Surabaya, and Sawahan (Nganjuk. The short-term of wind speed mean in monthly signifies to wind-speed value ”which parallels to the wind turbine power curve value” were used to estimate the annual energy output for a 1 MW installed capacity wind farm on the each site 100 of 10kW rated wind turbines were used in the analysis. The short term of wind speed mean at Surabaya and Nganjuk were 2.34, 3.03 and 1.97 m/s at 2 m Above Ground Level (AGL, respectively. In both locations, wind speeds were observed during the day time between 04.00 and 18.00 and relatively smaller ones between 19.00 and 03.00 period. Meanwhile, in Sampang (Madura the higher wind speeds were observed between 20.00 and 06.00, and relatively smaller between 07.00 and 19.00 period. The 1 MW windfarm at Sampang, Surabaya and Nganjuk can produce 1.284; 1.199 and 1.008 MWh of electricity yearly, taking into consideration of the temperature adjustment coefficien of about 6 %. The plant capacity factor at Sampang, Surabaya and Nganjuk were found to be 30.02 %, 30.00 % and 30.01 % respectively. Additionally, it is noticed that these site can contribute to the avoidance of 0.904; 0.846 and 0.709 tons/year of CO2 equivalent Green House Gases (GHG from entering into the local atmosphere, thus creating a clean and healthy athmosphere for local inhabitants.

  4. Stackelberg Game Model of Wind Farm and Electric Vehicle Battery Switch Station

    Science.gov (United States)

    Jiang, Zhe; Li, Zhimin; Li, Wenbo; Wang, Mingqiang; Wang, Mengxia

    2017-05-01

    In this paper, a cooperation method between wind farm and Electric vehicle battery switch station (EVBSS) was proposed. In the pursuit of maximizing their own benefits, the cooperation between wind farm and EVBSS was formulated as a Stackelberg game model by treating them as decision makers in different status. As the leader, wind farm will determine the charging/discharging price to induce the charging and discharging behavior of EVBSS reasonably. Through peak load shifting, wind farm could increase its profits by selling more wind power to the power grid during time interval with a higher purchase price. As the follower, EVBSS will charge or discharge according to the price determined by wind farm. Through optimizing the charging /discharging strategy, EVBSS will try to charge with a lower price and discharge with a higher price in order to increase its profits. Since the possible charging /discharging strategy of EVBSS is known, the wind farm will take the strategy into consideration while deciding the charging /discharging price, and will adjust the price accordingly to increase its profits. The case study proved that the proposed cooperation method and model were feasible and effective.

  5. Electric-field-driven domain wall dynamics in perpendicularly magnetized multilayers

    OpenAIRE

    González, Diego López; Shirahata, Yasuhiro; Van de Wiele, Ben; Franke, Kévin J. A.; Casiraghi, Arianna; Taniyama, Tomoyasu; van Dijken, Sebastiaan

    2017-01-01

    We report on reversible electric-field-driven magnetic domain wall motion in a Cu/Ni multilayer on a ferroelectric BaTiO3 substrate. In our heterostructure, strain-coupling to ferroelastic domains with in-plane and perpendicular polarization in the BaTiO3 substrate causes the formation of domains with perpendicular and in-plane magnetic anisotropy, respectively, in the Cu/Ni multilayer. Walls that separate magnetic domains are...

  6. A Data-Driven Diagnostic Framework for Wind Turbine Structures: A Holistic Approach

    Directory of Open Access Journals (Sweden)

    Simona Bogoevska

    2017-03-01

    Full Text Available The complex dynamics of operational wind turbine (WT structures challenges the applicability of existing structural health monitoring (SHM strategies for condition assessment. At the center of Europe’s renewable energy strategic planning, WT systems call for implementation of strategies that may describe the WT behavior in its complete operational spectrum. The framework proposed in this paper relies on the symbiotic treatment of acting environmental/operational variables and the monitored vibration response of the structure. The approach aims at accurate simulation of the temporal variability characterizing the WT dynamics, and subsequently at the tracking of the evolution of this variability in a longer-term horizon. The bi-component analysis tool is applied on long-term data, collected as part of continuous monitoring campaigns on two actual operating WT structures located in different sites in Germany. The obtained data-driven structural models verify the potential of the proposed strategy for development of an automated SHM diagnostic tool.

  7. Challenges in Measuring External Currents Driven by the Solar Wind-Magnetosphere Interaction

    Science.gov (United States)

    Le, Guan; Slavin, James A.; Pfaff, Robert F.

    2014-01-01

    In studying the Earth's geomagnetism, it has always been a challenge to separate magnetic fields from external currents originating from the ionosphere and magnetosphere. While the internal magnetic field changes very slowly in time scales of years and more, the ionospheric and magnetospheric current systems driven by the solar wind -magnetosphere interaction are very dynamic. They are intimately controlled by the ionospheric electrodynamics and ionospheremagnetosphere coupling. Single spacecraft observations are not able to separate their spatial and temporal variations, and thus to accurately describe their configurations. To characterize and understand the external currents, satellite observations require both good spatial and temporal resolutions. This paper reviews our observations of the external currents from two recent LEO satellite missions: Space Technology 5 (ST-5), NASA's first three-satellite constellation mission in LEO polar orbit, and Communications/Navigation Outage Forecasting System (C/NOFS), an equatorial satellite developed by US Air Force Research Laboratory. We present recommendations for future geomagnetism missions based on these observations.

  8. An Opportunistic Array Beamforming Technique Based on Binary Multiobjective Wind Driven Optimization Method

    Directory of Open Access Journals (Sweden)

    Zhenkai Zhang

    2015-01-01

    Full Text Available We present a novel binary version of multiobjective wind driven optimization (WDO for emitted beamforming of opportunistic array radar, which is assumed as a multiobjective optimization problem. Firstly, the emitted signal model and objective functions of optimization are presented. Then the algorithm proposes a new definition of the position vector of air parcel, and brings a good discretization interpretation of continuous WDO. For multiobjective optimization, the grey relational grade (GRG is then used to measure the similarity between the best two solutions for these two objectives. The best pressure locations with the maximum GRG will be recorded as the best two candidate solutions to the problem, and a final optimization result will be selected according to the importance of the two objectives. Finally, the proposed improved WDO has been applied for the optimal design of beamforming of the opportunistic antenna array, which needs a trade-off between the 3 dB main beam width and sidelobe level. The simulation results show that the proposed method outperforms conventional particle swarm optimization (PSO in the optimal beamforming by achieving more reduction in the sidelobe level and saving more runtime.

  9. Characteristics of heat flux and electromagnetic electron-cyclotron instabilities driven by solar wind electrons

    Science.gov (United States)

    Saeed, Sundas; Yoon, P. H.; Sarfraz, M.; Qureshi, M. N. S.

    2017-04-01

    In situ observations reveal the existence of electron velocity distribution function in the solar wind, where the net distribution can be modelled by a combination of core, halo and strahl. These components often possess a relative drift and with respective temperature anisotropies. The relative drift between the core and halo components leads to heat flux (HF) instability, while temperature anisotropies drive electromagnetic electron-cyclotron (EMEC) instability. These instabilities have been separately studied in the literature, but for the first time, the present study combines both unstable modes in the presence of two free energy sources, namely, excessive parallel pressure and excessive perpendicular temperature. HF instability (which is a left-hand circularly polarized mode) is effectively similar to electron firehose instability, except that the free energy is provided by net relative drift among two component electrons in the background of protons. The HF instability is discussed here along with (the right-hand polarized) EMEC instability driven by temperature anisotropy. The unstable HF mode is conventionally termed the 'whistler' HF instability, but it is actually polarized in the opposite sense to the whistler wave. EMEC mode, on the other hand, reduces to the proper whistler wave in the absence of free energy source. The present combined analysis clarifies the polarization characteristics of these two modes in an unambiguous manner.

  10. Wind-driven roof turbines: a novel way to improve ventilation for TB infection control in health facilities.

    Directory of Open Access Journals (Sweden)

    Helen Cox

    Full Text Available OBJECTIVE: Tuberculosis transmission in healthcare facilities contributes significantly to the TB epidemic, particularly in high HIV settings. Although improving ventilation may reduce transmission, there is a lack of evidence to support low-cost practical interventions. We assessed the efficacy of wind-driven roof turbines to achieve recommended ventilation rates, compared to current recommended practices for natural ventilation (opening windows, in primary care clinic rooms in Khayelitsha, South Africa. METHODS: Room ventilation was assessed (CO₂ gas tracer technique in 4 rooms where roof turbines and air-intake grates were installed, across three scenarios: turbine, grate and window closed, only window open, and only turbine and grate open, with concurrent wind speed measurement. 332 measurements were conducted over 24 months. FINDINGS: For all 4 rooms combined, median air changes per hour (ACH increased with wind speed quartiles across all scenarios. Higher median ACH were recorded with open roof turbines and grates, compared to open windows across all wind speed quartiles. Ventilation with open turbine and grate exceeded WHO-recommended levels (60 Litres/second/patient for 95% or more of measurements in 3 of the 4 rooms; 47% in the remaining room, where wind speeds were lower and a smaller diameter turbine was installed. CONCLUSION: High room ventilation rates, meeting recommended thresholds, may be achieved using wind-driven roof turbines and grates, even at low wind speeds. Roof turbines and air-intake grates are not easily closed by staff, allowing continued ventilation through colder periods. This simple, low-cost technology represents an important addition to our tools for TB infection control.

  11. Wind-driven roof turbines: a novel way to improve ventilation for TB infection control in health facilities.

    Science.gov (United States)

    Cox, Helen; Escombe, Rod; McDermid, Cheryl; Mtshemla, Yolanda; Spelman, Tim; Azevedo, Virginia; London, Leslie

    2012-01-01

    Tuberculosis transmission in healthcare facilities contributes significantly to the TB epidemic, particularly in high HIV settings. Although improving ventilation may reduce transmission, there is a lack of evidence to support low-cost practical interventions. We assessed the efficacy of wind-driven roof turbines to achieve recommended ventilation rates, compared to current recommended practices for natural ventilation (opening windows), in primary care clinic rooms in Khayelitsha, South Africa. Room ventilation was assessed (CO₂ gas tracer technique) in 4 rooms where roof turbines and air-intake grates were installed, across three scenarios: turbine, grate and window closed, only window open, and only turbine and grate open, with concurrent wind speed measurement. 332 measurements were conducted over 24 months. For all 4 rooms combined, median air changes per hour (ACH) increased with wind speed quartiles across all scenarios. Higher median ACH were recorded with open roof turbines and grates, compared to open windows across all wind speed quartiles. Ventilation with open turbine and grate exceeded WHO-recommended levels (60 Litres/second/patient) for 95% or more of measurements in 3 of the 4 rooms; 47% in the remaining room, where wind speeds were lower and a smaller diameter turbine was installed. High room ventilation rates, meeting recommended thresholds, may be achieved using wind-driven roof turbines and grates, even at low wind speeds. Roof turbines and air-intake grates are not easily closed by staff, allowing continued ventilation through colder periods. This simple, low-cost technology represents an important addition to our tools for TB infection control.

  12. Synthesis of black magnetic electrophoretic particles for magnetic-electric dual-driven electronic paper.

    Science.gov (United States)

    Meng, Xianwei; Qiang, Li; Su, Xiaofang; Ren, Jun; Tang, Fangqiong

    2013-02-01

    The application of electronic paper (e-paper) is now propelling the development of the multifunctional e-paper products. There is an extraordinary diversity of basic and applied research in pursuit of the novel e-paper. Here, we report the first achievement of a magnetic-electric dual-driven e-paper, using black magnetic electrophoretic particles (BMEPs). BMEPs are synthesized via a facile, green, low-cost, one-step method. By adjusting the reaction conditions, the density, surface, and magnetic properties of the BMEPs are optimized for e-paper display. Finally, the e-paper display is successfully assembled using dispersion of the BMEPs in a mixed dielectric solvent with white particles as contrast. Thanks to the magnetic properties and a positively charged surface, the BMEPs can be driven by both electric and magnetic fields. The prototype display is fabricated whose switch is achieved by the application of either a bias voltage of 10 V or a magnetic bias. The as-prepared magnetic-electric dual-driven device could have many promising applications in the field of anticounterfeiting labels for secure identification documents.

  13. Gait Planning Research for an Electrically Driven Large-Load-Ratio Six-Legged Robot

    Directory of Open Access Journals (Sweden)

    Hong-Chao Zhuang

    2017-03-01

    Full Text Available Gait planning is an important basis for the walking of a legged robot. To improve the walking stability of multi-legged robots and to reduce the impact force between the foot and the ground, gait planning strategies are presented for an electrically driven large-load-ratio six-legged robot. First, the configuration and walking gait of the electrically driven large-load-ratio six-legged robot are designed. The higher-stable swing sequences of legs and typical walking modes are respectively obtained. Based on the Denavit–Hartenberg (D–H method, the analyses of the forward and inverse kinematics are implemented. The mathematical models of the articulated rotation angles are respectively established. In view of the buffer device installed at the end of shin to decrease the impact force between the foot and the ground, an initial lift height of the leg is brought into gait planning when the support phase changes into the transfer phase. The mathematical models of foot trajectories are established. Finally, a prototype of the electrically driven large-load-ratio six-legged robot is developed. The experiments of the prototype are carried out regarding the aspects of the walking speed and surmounting obstacle. Then, the reasonableness of gait planning is verified based on the experimental results. The proposed strategies of gait planning lay the foundation for effectively reducing the foot–ground impact force and can provide a reference for other large-load-ratio multi-legged robots.

  14. Electric vehicles in Danish power system with large penetration of wind power

    DEFF Research Database (Denmark)

    Yang, Lihui; Xu, Zhao; Østergaard, Jacob

    2011-01-01

    Electric vehicles (EVs) provide a unique opportunity for reducing the CO2 emissions from the transport sector. At the same time, EVs have the potential to play an important role in the economical and reliable operation of an electricity system with high penetration of renewable energy. An analysis...... is made of the potential for using EVs in Denmark, and the benefits of the electric power system with high wind power generation by intelligent charging and discharging of EVs are enumerated. Based on the analysis, important technological gaps are identified, and the corresponding research and development...... initiatives of the recently established EDISON program are described. Moreover, the latest development of the EDISON program is treated, that is, EDISON as a research consortium to design a new model for the Danish power system with high penetration of wind power and EVs with vehicle to grid (V2G...

  15. Reversal of subtidal dune asymmetries caused by seasonally reversing wind-driven currents in Torres Strait, northeastern Australia

    Science.gov (United States)

    Harris, Peter T.

    1991-07-01

    Large subtidal sand dunes (sandwaves) located in Adolphus Channel, Torres Strait, have been observed to reverse their asymmetric orientation between September-February. This has been attributed to a reversal in wind-driven currents, which flow westward during the SE trade season (April-November) and eastwards during the NW monsoon season [December-March: HARRIS (1989) Continental Shelf Research, 9, 981-1002]. Observations in September 1988 and February 1989 from another area of dunes in Torres Strait corroborate this asymmetry reversal pattern. The results indicate that such reversals may be common in Torres Strait and in other areas where subtidal bedforms are subject to modification by superimposed, seasonally reversing, wind-driven currents.

  16. Method for analysing the adequacy of electric power systems with wind power plants and energy storages

    Directory of Open Access Journals (Sweden)

    Perzhabinsky Sergey

    2017-01-01

    Full Text Available Currently, renewable energy sources and energy storage devices are actively introduced into electric power systems. We developed method to analyze the adequacy of these electric power systems. The method takes into account the uncertainty of electricity generation by wind power plants and the processes of energy storage. The method is based on the Monte Carlo method and allowed to use of long-term meteorological data in open access. The performed experimental research of electrical power system is constructed on the basis of the real technical and meteorological data. The method allows to estimate of effectiveness of introducing generators based on renewable energy sources and energy storages in electric power systems.

  17. Price Forecasting of Electricity Markets in the Presence of a High Penetration of Wind Power Generators

    Directory of Open Access Journals (Sweden)

    Saber Talari

    2017-11-01

    Full Text Available Price forecasting plays a vital role in the day-ahead markets. Once sellers and buyers access an accurate price forecasting, managing the economic risk can be conducted appropriately through offering or bidding suitable prices. In networks with high wind power penetration, the electricity price is influenced by wind energy; therefore, price forecasting can be more complicated. This paper proposes a novel hybrid approach for price forecasting of day-ahead markets, with high penetration of wind generators based on Wavelet transform, bivariate Auto-Regressive Integrated Moving Average (ARIMA method and Radial Basis Function Neural Network (RBFN. To this end, a weighted time series for wind dominated power systems is calculated and added to a bivariate ARIMA model along with the price time series. Moreover, RBFN is applied as a tool to correct the estimation error, and particle swarm optimization (PSO is used to optimize the structure and adapt the RBFN to the particular training set. This method is evaluated on the Spanish electricity market, which shows the efficiency of this approach. This method has less error compared with other methods especially when it considers the effects of large-scale wind generators.

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

    Energy Technology Data Exchange (ETDEWEB)

    Moroz, E.M.; Parks, N.J.; Swift, A.H.; Traichal, P.A. [Univ. of Texas, El Paso, TX (United States)

    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.

  19. IRONLESS PERMANENT MAGNET GENERATORS FOR DIRECT-DRIVEN OFFSHORE WIND TURBINES

    OpenAIRE

    Zhaoqiang, Zhang

    2015-01-01

    Since the beginning of this century, the offshore wind power industry has witnessed fast development, as the result of the increasing awareness of climate change and the need for diversifying power supply. Offshore has vast area available with high wind speed, which is an ideal place for large-scale wind power exploitation. However, these advantages come with technological challenges. One of the key challenges is to develop high-power cost-effective wind turbines with high r...

  20. Combined scheduling of electricity and heat in a microgrid with volatile wind power

    DEFF Research Database (Denmark)

    Xu, Lizhong; Yang, Guang Ya; Xu, Zhao

    2011-01-01

    An optimization model is developed for scheduling electricity and heat production in a microgrid under a day-ahead market environment considering the operation constraints and the volatility of wind power generation. The model optimizes the total operation costs from energy and heating consumption...... into a mixed-integer programming (MIP) problem. Numerical simulations present the efficacy of the proposed model for day-ahead scheduling of a microgrid with wind penetration under the deregulated environment. © 2011 State Grid Electrtic Resarch Institute Press....

  1. An Interconnected Wind Driven SEIG System Using SVPWM Controlled TL Z-Source Inverter Strategy for Off-Shore WECS

    Directory of Open Access Journals (Sweden)

    Ajin Sekhar CS

    2013-09-01

    Full Text Available This paper discuss about  the interconnection of wind driven SEIG for drive applications by using TL Z-source inverter strategy .TL Z-source consists of two coupled inductors having turns ratio γTL and four diodes are used . The wind energy system uses a two Self Excited Induction generator (SEIG connected parallel in order to increase the reliability. The proposed system components like wind turbine SEIG, rectifier, SVM Controlled TL Z-source inverter, are modeled by matlab Simulink. The maximum power can be extracted and supplied to the load efficiently by using TL Z-source inverter with a proper value of modulation index. The simulation output is analysed experimentally using 500 W experimental setup.

  2. Iterative data-driven load control for flexible wind turbine rotors

    NARCIS (Netherlands)

    Navalkar, S.T.

    2016-01-01

    Wind energy has reached a high degree ofmaturity: for wind-rich onshore locations, it is already competitive with conventional energy sources. However, for low-wind, remote and offshore regions, research efforts are still required to enhance its economic viability. While it is possible to reduce the

  3. Preliminary Investigation on Generation of Electricity Using Micro Wind Turbines Placed on A Car

    Directory of Open Access Journals (Sweden)

    Yogendra Chaudhary

    2017-03-01

    Full Text Available Wind energy is one of the prominent resources for renewable energy and it is traditionally extracted using stationary wind turbines. However, it can also be extracted using mini or micro wind turbines on a moving body, such as an automobile, while cruising at high speeds on freeways. If the electricity is produced using air flowing around the vehicle without affecting aerodynamic performance of the vehicle, it can be used to charge up the battery or power up additional accessories of the vehicle. For the first time, in the present work, a preliminary investigation was carried out to generate electricity by utilizing air flow on a moving car. Initially, a correlation between the car speed and wind velocity was established using an anemometer. Placing a set of two micro wind turbines along with two micro generators on the rear end of the car trunk, the present study investigated the feasibility of generating electricity from these micro wind turbines while evaluating the effect of drag force on the performance of the car through the experimental approach and computational fluid dynamics (CFD simulations. Both approaches confirmed negligible effect of drag force on the vehicle performance in terms of gas mileage and changes in drag coefficient values. Following these studies, the micro wind turbines were also tested for electricity generation at various cruising speeds of the car ranging from 50 to 80 mph on the freeways. The voltage and power generated always showed an increasing trend with increasing the car speed, however they saturated when a cut off limit was setup with the voltage controllers. A maximum voltage of 3.5 V and a maximum current of 0.8 A were generated by each micro wind turbine when a cut off limit was used along with a load consisting of four LED bulbs in parallel with 3.5 V and 0.2 A rating each. On the other hand, when the tests were repeated without using the cut-off limit, a maximum voltage of 18.91 V and a maximum current

  4. Avalanche breakdown and self-stabilization effects in electrically driven transition of carbon nanotube covered VO2 film

    Science.gov (United States)

    Chen, Yuliang; Chen, Shi; Liu, Qianghu; Ren, Hui; Zheng, Xusheng; Wang, Liangxin; Lu, Yuan; Song, Li; Zhang, Guobin; Zou, Chongwen

    2017-06-01

    Electrical-driven metal-insulator transition (MIT) is quite vital and widespread for both applications and MIT mechanism of VO2. In this report, we discussed the avalanche breakdown and self-stabilization effects behind the electrically driven phase transition in macro-scale carbon nanotube covered VO2 film to further understand the phase transition behaviors as well as explore promising electrical-driven VO2 devices. It was found that the Joule heat was the main source to trigger the phase transition of VO2 film. However, the time-dependent triggering routes were quite different, since the avalanche behavior was observed under the voltage-driven mode, while the gradual self-stabilization existed in the current-driven mode. The simulation results based on the proposed thermodynamics models were in good agreement with the experimental phenomena, which were basically originated from the intrinsic first-order phase transition properties of VO2 film.

  5. Single-sided natural ventilation driven by wind pressure and temperature difference

    DEFF Research Database (Denmark)

    Larsen, Tine Steen; Heiselberg, Per

    2008-01-01

    -scale wind tunnel experiments have been made with the aim of making a new expression for calculation of the airflow rate in single-sided natural ventilation. During the wind tunnel experiments it was found that the dominating driving force differs between wind speed and temperature difference depending......Even though opening a window for ventilation of a room seems very simple, the flow that occurs in this situation is rather complicated. The amount of air going through the window opening will depend on the wind speed near the building, the temperatures inside and outside the room, the wind...

  6. Wind Energy Study and Energy Cost of Wind Electricity Generation in Nigeria: Past and Recent Results and a Case Study for South West Nigeria

    Directory of Open Access Journals (Sweden)

    Oluseyi O. Ajayi

    2014-12-01

    Full Text Available The study assessed the wind energy potential of ten selected sites in the south western region of Nigeria and carried out a cost benefit analysis of wind power generation at those sites. Twenty four years’ (1987 to 2010 wind speed data at 10 m height obtained from the Nigerian meteorological agency were employed to classify the sites wind profiles for electricity generation. The energy cost analysis of generating wind electricity from the sites was also carried out. The outcome showed that sites in Lagos and Oyo States were adequately suited for large scale generation with average wind speeds ranged between 2.9 and 5.8 m/s. Those from other sites may be suitable for small scale generation or as wind farms, with several small turbines connected together, to generate large enough wind power. The turbine matching results shows that turbines cut-in and rated wind speeds of between 2.0 and 3.0 m/s, and between 10 and 12.0 m/s respectively will be very suited to all the sites, particularly those in locations outside Lagos and Oyo States. The energy cost analysis shows that generation cost can be as low as 0.02 €/kWh and as high as 5.03/kWh, depending on the turbine model employed.

  7. Rotor Speed Control of a Direct-Driven Permanent Magnet Synchronous Generator-Based Wind Turbine Using Phase-Lag Compensators to Optimize Wind Power Extraction

    Directory of Open Access Journals (Sweden)

    Ester Hamatwi

    2017-01-01

    Full Text Available Due to the intermittent nature of wind, the wind power output tends to be inconsistent, and hence maximum power point tracking (MPPT is usually employed to optimize the power extracted from the wind resource at a wide range of wind speeds. This paper deals with the rotor speed control of a 2 MW direct-driven permanent magnet synchronous generator (PMSG to achieve MPPT. The proportional-integral (PI, proportional-derivative (PD, and proportional-integral-derivative (PID controllers have widely been employed in MPPT studies owing to their simple structure and simple design procedure. However, there are a number of shortcomings associated with these controllers; the trial-and-error design procedure used to determine the P, I, and D gains presents a possibility for poorly tuned controller gains, which reduces the accuracy and the dynamic performance of the entire control system. Moreover, these controllers’ linear nature, constricted operating range, and their sensitivity to changes in machine parameters make them ineffective when applied to nonlinear and uncertain systems. On the other hand, phase-lag compensators are associated with a design procedure that is well defined from fundamental principles as opposed to the aforementioned trial-and-error design procedure. This makes the latter controller type more accurate, although it is not well developed yet, and hence it is the focus of this paper. The simulation results demonstrated the effectiveness of the proposed MPPT controller.

  8. EFFECTS OF THE PENETRATION OF WIND POWER IN THE BRAZILIAN ELECTRICITY MARKET

    Directory of Open Access Journals (Sweden)

    Milton M. Herrera

    2016-12-01

    Full Text Available Climate variability has been the main driver for renewables in the Brazilian electricity market. This article analyzes the vulnerabilities of the dependence on hydropower in renewable energy production due to climate variation, as well as wind power penetration in Brazil, given a set of wind industry policies. Despite Brazilian renewable energy increase, the study shows the impact in energy supply in north region, due to the lack of transmission infrastructure. In Brazil, the potential trade-offs between renewables growth, and transmission infrastructure inconsistencies in terms of policy implementation are not yet well analyzed. Simulation results show the potential conflicts between energy policies aimed at increasing the wind power supply and boundaries in transmission infrastructure.

  9. Particle Velocity Distributions and Large-Scale Electric Field in Solar Wind

    Science.gov (United States)

    Pavan, J.; Vinas, A. F.

    2016-12-01

    Velocity distributions of particles are key elements in the study of solar wind. The physical mechanisms that regulate their many features are a matter of debate. The present work addresses the subject with a fully analytical method in order to establish the shape of particle velocity distributions in solar wind. The method consists in solving the steady-state kinetic equation for particles and the related fluid equations, assigning spatial profiles for density and temperature matching observational data. The model is one-dimensional in configuration-space and two-dimensional in velocity-space, and accounts for large-scale processes, namely, advection, gravity, magnetic mirroring and the large-scale ambipolar electric field, without the aid of wave-particle interactions or collisions. The findings reported add to the general understanding of regulation of particle distributions in solar wind and to the predictions of their shape in regions restricted for in situ measurements.

  10. Probabilistic Constrained Load Flow Considering Integration of Wind Power Generation and Electric Vehicles

    DEFF Research Database (Denmark)

    Vlachogiannis, Ioannis (John)

    2009-01-01

    A new formulation and solution of probabilistic constrained load flow (PCLF) problem suitable for modern power systems with wind power generation and electric vehicles (EV) demand or supply is represented. The developed stochastic model of EV demand/supply and the wind power generation model...... is applied to a new introduced 14-busbar test system which comprises two wind turbine (WT) generators, one small power plant, and two EV-plug-in stations connected at two PQ buses. The results demonstrate the excellent performance of the HLAS for PCLF problem. New formulae to facilitate the optimal...... are incorporated into load flow studies. In the resulted PCLF formulation, discrete and continuous control parameters are engaged. Therefore, a hybrid learning automata system (HLAS) is developed to find the optimal offline control settings over a whole planning period of power system. The process of HLAS...

  11. Rolling scheduling of electric power system with wind power based on improved NNIA algorithm

    Science.gov (United States)

    Xu, Q. S.; Luo, C. J.; Yang, D. J.; Fan, Y. H.; Sang, Z. X.; Lei, H.

    2017-11-01

    This paper puts forth a rolling modification strategy for day-ahead scheduling of electric power system with wind power, which takes the operation cost increment of unit and curtailed wind power of power grid as double modification functions. Additionally, an improved Nondominated Neighbor Immune Algorithm (NNIA) is proposed for solution. The proposed rolling scheduling model has further improved the operation cost of system in the intra-day generation process, enhanced the system’s accommodation capacity of wind power, and modified the key transmission section power flow in a rolling manner to satisfy the security constraint of power grid. The improved NNIA algorithm has defined an antibody preference relation model based on equal incremental rate, regulation deviation constraints and maximum & minimum technical outputs of units. The model can noticeably guide the direction of antibody evolution, and significantly speed up the process of algorithm convergence to final solution, and enhance the local search capability.

  12. Electrical Structure of Future Off-shore Wind Power Plant with a High Voltage Direct Current Power Transmission

    OpenAIRE

    Sharma, Ranjan; Andersen, Michael A. E.; Akhmatov, Vladislav; Jensen, Kim Høj; Rasmussen, Tonny Wederberg

    2012-01-01

    The increasing demand of electric power and the growing consciousness towards the changing climate has led to a rapid development of renewable energy in the recent years. Among all, wind energy has been the fastest growing energy source in the last decade. But the growing size of wind power plants, better wind conditions at off-shore and the general demand to put them out of sight have all contributed to the installation of large wind power plants in off-shore condition. However, moving wind ...

  13. Analysing the impact of renewable electricity support schemes on power prices: The case of wind electricity in Spain

    Energy Technology Data Exchange (ETDEWEB)

    Saenz de Miera, Gonzalo [Department of Public Economics, Universidad Autonoma de Madrid, Campus de Cantoblanco, Madrid 28049 (Spain); del Rio Gonzalez, Pablo [Institute for Public Policies, Centro de Ciencias Humanas y Sociales, CSIC, C/Albasanz 26-28, 28037 Madrid (Spain); Vizcaino, Ignacio [Iberdrola, C/Tomas Redondo, 1, Madrid 28033 (Spain)

    2008-09-15

    It is sometimes argued that renewables are 'expensive'. However, although it is generally true that the private costs of renewable electricity generation are certainly above those of conventional electricity, that statement fails to consider the social benefits provided by electricity from renewable energy sources (RES-E), including environmental and socioeconomic ones. This paper empirically analyses an additional albeit usually neglected benefit: the reduction in the wholesale price of electricity as a result of more RES-E generation being fed into the grid. The case of wind generation in Spain shows that this reduction is greater than the increase in the costs for the consumers arising from the RES-E support scheme (the feed-in tariffs), which are charged to the final consumer. Therefore, a net reduction in the retail electricity price results, which is positive from a consumer point of view. This provides an additional argument for RES-E support and contradicts one of the usual arguments against RES-E deployment: the excessive burden on the consumer. (author)

  14. Data-driven estimation of cardiac electrical diffusivity from 12-lead ECG signals.

    Science.gov (United States)

    Zettinig, Oliver; Mansi, Tommaso; Neumann, Dominik; Georgescu, Bogdan; Rapaka, Saikiran; Seegerer, Philipp; Kayvanpour, Elham; Sedaghat-Hamedani, Farbod; Amr, Ali; Haas, Jan; Steen, Henning; Katus, Hugo; Meder, Benjamin; Navab, Nassir; Kamen, Ali; Comaniciu, Dorin

    2014-12-01

    Diagnosis and treatment of dilated cardiomyopathy (DCM) is challenging due to a large variety of causes and disease stages. Computational models of cardiac electrophysiology (EP) can be used to improve the assessment and prognosis of DCM, plan therapies and predict their outcome, but require personalization. In this work, we present a data-driven approach to estimate the electrical diffusivity parameter of an EP model from standard 12-lead electrocardiograms (ECG). An efficient forward model based on a mono-domain, phenomenological Lattice-Boltzmann model of cardiac EP, and a boundary element-based mapping of potentials to the body surface is employed. The electrical diffusivity of myocardium, left ventricle and right ventricle endocardium is then estimated using polynomial regression which takes as input the QRS duration and electrical axis. After validating the forward model, we computed 9500 EP simulations on 19 different DCM patients in just under three seconds each to learn the regression model. Using this database, we quantify the intrinsic uncertainty of electrical diffusion for given ECG features and show in a leave-one-patient-out cross-validation that the regression method is able to predict myocardium diffusion within the uncertainty range. Finally, our approach is tested on the 19 cases using their clinical ECG. 84% of them could be personalized using our method, yielding mean prediction errors of 18.7ms for the QRS duration and 6.5° for the electrical axis, both values being within clinical acceptability. By providing an estimate of diffusion parameters from readily available clinical data, our data-driven approach could therefore constitute a first calibration step toward a more complete personalization of cardiac EP. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Broadband modulation of terahertz waves through electrically driven hybrid bowtie antenna-VO2 devices.

    Science.gov (United States)

    Han, Chunrui; Parrott, Edward P J; Humbert, Georges; Crunteanu, Aurelian; Pickwell-MacPherson, Emma

    2017-10-05

    Broadband modulation of terahertz (THz) light is experimentally realized through the electrically driven metal-insulator phase transition of vanadium dioxide (VO2) in hybrid metal antenna-VO2 devices. The devices consist of VO2 active layers and bowtie antenna arrays, such that the electrically driven phase transition can be realized by applying an external voltage between adjacent metal wires extended to a large area array. The modulation depth of the terahertz light can be initially enhanced by the metal wires on top of VO2 and then improved through the addition of specific bowties in between the wires. As a result, a terahertz wave with a large beam size (~10 mm) can be modulated within the measurable spectral range (0.3-2.5 THz) with a frequency independent modulation depth as high as 0.9, and the minimum amplitude transmission down to 0.06. Moreover, the electrical switch on/off phase transition depends very much on the size of the VO2 area, indicating that smaller VO2 regions lead to higher modulation speeds and lower phase transition voltages. With the capabilities in actively tuning the beam size, modulation depth, modulation bandwidth as well as the modulation speed of THz waves, our study paves the way in implementing multifunctional components for terahertz applications.

  16. Electric-field-driven Phenomena for Manipulating Particles in Micro-Devices

    Science.gov (United States)

    Khusid, Boris; Acrivos, Andreas

    2004-01-01

    Compared to other available methods, ac dielectrophoresis is particularly well-suited for the manipulation of minute particles in micro- and nano-fluidics. The essential advantage of this technique is that an ac field at a sufficiently high frequency suppresses unwanted electric effects in a liquid. To date very little has been achieved towards understanding the micro-scale field-and shear driven behavior of a suspension in that, the concepts currently favored for the design and operation of dielectrophoretic micro-devices adopt the approach used for macro-scale electric filters. This strategy considers the trend of the field-induced particle motions by computing the spatial distribution of the field strength over a channel as if it were filled only with a liquid and then evaluating the direction of the dielectrophoretic force, exerted on a single particle placed in the liquid. However, the exposure of suspended particles to a field generates not only the dielectrophoretic force acting on each of these particles, but also the dipolar interactions of the particles due to their polarization. Furthermore, the field-driven motion of the particles is accompanied by their hydrodynamic interactions. We present the results of our experimental and theoretical studies which indicate that, under certain conditions, these long-range electrical and hydrodynamic interparticle interactions drastically affect the suspension behavior in a micro-channel due to its small dimensions.

  17. Equivalent circuit and characteristic simulation of a brushless electrically excited synchronous wind power generator

    Science.gov (United States)

    Wang, Hao; Zhang, Fengge; Guan, Tao; Yu, Siyang

    2017-09-01

    A brushless electrically excited synchronous generator (BEESG) with a hybrid rotor is a novel electrically excited synchronous generator. The BEESG proposed in this paper is composed of a conventional stator with two different sets of windings with different pole numbers, and a hybrid rotor with powerful coupling capacity. The pole number of the rotor is different from those of the stator windings. Thus, an analysis method different from that applied to conventional generators should be applied to the BEESG. In view of this problem, the equivalent circuit and electromagnetic torque expression of the BEESG are derived on the basis of electromagnetic relation of the proposed generator. The generator is simulated and tested experimentally using the established equivalent circuit model. The experimental and simulation data are then analyzed and compared. Results show the validity of the equivalent circuit model.

  18. Meeting the Electrical Energy Needs of a Residential Building with a Wind-Photovoltaic Hybrid System

    Directory of Open Access Journals (Sweden)

    Mohammad Hosein Mohammadnezami

    2015-03-01

    Full Text Available A complete hybrid system including a photovoltaic cell, a wind turbine, and battery is modeled to determine the best approach for sizing the system to meet the electrical energy needs of a residential building. In evaluating system performance, the city of Tehran is used as a case study. Matlab software is used for analyzing the data and optimizing the system for the given application. Further, the cost of the system design is investigated, and shows that the electrical cost of the hybrid system in Tehran is 0.62 US$/kWh, which is 78% less expensive than a wind turbine system and 34% less expensive than a photovoltaic system.

  19. On the impact of radiation pressure on the dynamics and inner structure of dusty wind-driven shells

    Energy Technology Data Exchange (ETDEWEB)

    Martínez-González, Sergio; Silich, Sergiy; Tenorio-Tagle, Guillermo, E-mail: silich@inaoep.mx [Instituto Nacional de Astrofísica Óptica y Electrónica, AP 51, 72000 Puebla (Mexico)

    2014-04-20

    Massive young stellar clusters are strong sources of radiation and mechanical energy. Their powerful winds and radiation pressure sweep up interstellar gas into thin expanding shells that trap the ionizing radiation produced by the central clusters affecting the dynamics and the distribution of their ionized gas. Here we continue our comparison of the star cluster winds and radiation pressure effects on the dynamics of shells around young massive clusters. We calculate the impact that radiation pressure has on the distribution of matter and thermal pressure within such shells, as well as on the density-weighted ionization parameter U{sub w} , and put our results on the diagnostic diagram, which allows one to discriminate between the wind-dominated and radiation-dominated regimes. We found that model-predicted values of the ionization parameter agree well with typical values found in local starburst galaxies. Radiation pressure may affect the inner structure and the dynamics of wind-driven shells, but only during the earliest stages of evolution (before ∼3 Myr) or if a major fraction of the star cluster mechanical luminosity is dissipated or radiated away within the star cluster volume and thus the star cluster mechanical energy output is significantly smaller than star cluster synthetic models predict. However, even in these cases radiation dominates over the wind dynamical pressure only if the exciting cluster is embedded into a high-density ambient medium.

  20. A data-driven multi-model methodology with deep feature selection for short-term wind forecasting

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Cong; Cui, Mingjian; Hodge, Bri-Mathias; Zhang, Jie

    2017-03-01

    With the growing wind penetration into the power system worldwide, improving wind power forecasting accuracy is becoming increasingly important to ensure continued economic and reliable power system operations. In this paper, a data-driven multi-model wind forecasting methodology is developed with a two-layer ensemble machine learning technique. The first layer is composed of multiple machine learning models that generate individual forecasts. A deep feature selection framework is developed to determine the most suitable inputs to the first layer machine learning models. Then, a blending algorithm is applied in the second layer to create an ensemble of the forecasts produced by first layer models and generate both deterministic and probabilistic forecasts. This two-layer model seeks to utilize the statistically different characteristics of each machine learning algorithm. A number of machine learning algorithms are selected and compared in both layers. This developed multi-model wind forecasting methodology is compared to several benchmarks. The effectiveness of the proposed methodology is evaluated to provide 1-hour-ahead wind speed forecasting at seven locations of the Surface Radiation network. Numerical results show that comparing to the single-algorithm models, the developed multi-model framework with deep feature selection procedure has improved the forecasting accuracy by up to 30%.

  1. Evaluation of the Impact of Wind Generation on the Electricity Market Prices and on the Profitability of New Wind Investments

    Directory of Open Access Journals (Sweden)

    Saraiva J. T.

    2012-10-01

    Full Text Available This paper describes a Dynamic Model of the electricity sector that can be used to simulate the evolution of some key variables on the long term, namely the evolution of the electricity price, of the demand and of the capacity factors of the technologies in the generation mix. This model can be used in different ways and by several agents, for instance to estimate the impact on the electricity price of the increasing presence of renewable power stations, namely using wind power and PV systems. In several countries these stations are paid feed-in tariffs with a fixed price but in some cases this scheme is under discussion and there are opinions that payments determined by the market price are more adequate and would bring fewer costs to final consumers. Such a change has to be carefully evaluated given that the presence of renewable stations bidding at an infra marginal price will affect the price itself. The model described in this paper can be used in a profitable way both by governmental agencies when preparing or studying alternative remuneration schemes to renewable stations or by promoters themselves to get more insight to the profitability of their investments, namely if the fixed feed-in tariffs in force in several countries are changed.

  2. Cosmic ray-driven winds in the Galactic environment and the cosmic ray spectrum

    Science.gov (United States)

    Recchia, S.; Blasi, P.; Morlino, G.

    2017-09-01

    Cosmic rays escaping the Galaxy exert a force on the interstellar medium directed away from the Galactic disc. If this force is larger than the gravitational pull due to the mass embedded in the Galaxy, then galactic winds may be launched. Such outflows may have important implications for the history of star formation of the host galaxy, and in turn affect in a crucial way the transport of cosmic rays, both due to advection with the wind and to the excitation of waves by the same cosmic rays, through streaming instability. The possibility to launch cosmic ray-induced winds and the properties of such winds depend on environmental conditions, such as the density and temperature of the plasma at the base of the wind and the gravitational potential, especially the one contributed by the dark matter halo. In this paper, we make a critical assessment of the possibility to launch cosmic ray-induced winds for a Milky Way-like galaxy and how the properties of the wind depend upon the conditions at the base of the wind. Special attention is devoted to the implications of different conditions for wind launching on the spectrum of cosmic rays observed at different locations in the disc of the galaxy. We also comment on how cosmic ray-induced winds compare with recent observations of Oxygen absorption lines in quasar spectra and emission lines from blank sky, as measured by XMM-Newton/EPIC-MOS.

  3. Electric field driven evolution of topological domain structure in hexagonal manganites

    Science.gov (United States)

    Yang, K. L.; Zhang, Y.; Zheng, S. H.; Lin, L.; Yan, Z. B.; Liu, J.-M.; Cheong, S.-W.

    2017-10-01

    Controlling and manipulating the topological state represents an important topic in condensed matters for both fundamental researches and applications. In this work, we focus on the evolution of a real-space topological domain structure in hexagonal manganites driven by electric field, using the analytical and numerical calculations based on the Ginzburg-Landau theory. It is revealed that the electric field drives a transition of the topological domain structure from the type-I pattern to the type-II one. In particular, it is identified that a high electric field can enforce the two antiphase-plus-ferroelectric (AP +FE ) domain walls with Δ Φ =π /3 to approach each other and to merge into one domain wall with Δ Φ = 2 π /3 eventually if the electric field is sufficiently high, where Δ Φ is the difference in the trimerization phase between two neighboring domains. Our simulations also reveal that the vortex cores of the topological structure can be disabled at a sufficiently high critical electric field by suppressing the structural trimerization therein, beyond which the vortex core region is replaced by a single ferroelectric domain without structural trimerization (Q = 0 ). Our results provide a stimulating reference for understanding the manipulation of real-space topological domain structure in hexagonal manganites.

  4. Electric-field-driven magnetic domain wall as a microscale magneto-optical shutter.

    Science.gov (United States)

    Khokhlov, Nikolai E; Khramova, Anastasiya E; Nikolaeva, Elena P; Kosykh, Tatyana B; Nikolaev, Alexey V; Zvezdin, Anatoly K; Pyatakov, Alexander P; Belotelov, Vladimir I

    2017-03-21

    Nowadays, spintronics considers magnetic domain walls as a kind of nanodeviсe that demands for switching much less energy in comparison to homogeneous process. We propose and demonstrate a new concept for the light control via electric field applied locally to a magnetic domain wall playing the role of nanodevice. In detail, we charged a 15-μm-thick metallic tip to generate strong non-uniform electric field in the vicinity of the domain wall in the iron garnet film. The electric field influences the domain wall due to flexomagnetoelectric effect and causes the domain wall shift. The resulting displacement of the domain wall is up to 1/3 of domain width and allows to demonstrate a novel type of the electrically controlled magneto-optical shutter. Polarized laser beam focused on the electric-field-driven domain wall was used to demonstrate the concept of a microscale Faraday modulator. We obtained different regimes of the light modulation - linear, nonlinear and tri-stable - for the same domain wall with corresponding controllable displacement features. Such variability to control of domain wall's displacement with spatial scale of about 10 μm makes the proposed concept very promising for nanophotonics and spintronics.

  5. Comparative Study between Two Market Clearing Schemes in Wind Dominant Electricity Markets

    DEFF Research Database (Denmark)

    Farashbashi-Astaneh, Seyed-Mostafa; Hu, Weihao; Chen, Zhe

    2015-01-01

    . According to the proposed agent-based approach, electricity market agents (here generation units) learn from their previous bidding experience to obtain maximum financial. A comparative study is then conducted to investigate the impact of mentioned pricing schemes on price volatility and average price level......High price volatility and excessive price reduction are introduced as two emerging problems in wind dominant electricity markets. In this study, an agent-based simulation methodology is employed to investigate the impact of two pricing mechanisms, uniform and pay-as-bid, on the mentioned problems...

  6. Preliminary Assessment of Plug-in Hybrid Electric Vehicles on Wind Energy Markets

    Energy Technology Data Exchange (ETDEWEB)

    Short, W.; Denholm, P.

    2006-04-01

    This report examines a measure that may potentially reduce oil use and also more than proportionately reduce carbon emissions from vehicles. The authors present a very preliminary analysis of plug-in hybrid electric vehicles (PHEVs) that can be charged from or discharged to the grid. These vehicles have the potential to reduce gasoline consumption and carbon emissions from vehicles, as well as improve the viability of renewable energy technologies with variable resource availability. This paper is an assessment of the synergisms between plug-in hybrid electric vehicles and wind energy. The authors examine two bounding cases that illuminate this potential synergism.

  7. Extreme fire severity patterns in topographic, convective and wind-driven historical wildfires of Mediterranean pine forests.

    Directory of Open Access Journals (Sweden)

    Judit Lecina-Diaz

    Full Text Available Crown fires associated with extreme fire severity are extremely difficult to control. We have assessed fire severity using differenced Normalized Burn Ratio (dNBR from Landsat imagery in 15 historical wildfires of Pinus halepensis Mill. We have considered a wide range of innovative topographic, fuel and fire behavior variables with the purposes of (1 determining the variables that influence fire severity patterns among fires (considering the 15 wildfires together and (2 ascertaining whether different variables affect extreme fire severity within the three fire types (topographic, convective and wind-driven fires. The among-fires analysis showed that fires in less arid climates and with steeper slopes had more extreme severity. In less arid conditions there was more crown fuel accumulation and closer forest structures, promoting high vertical and horizontal fuel continuity and extreme fire severity. The analyses carried out for each fire separately (within fires showed more extreme fire severity in areas in northern aspects, with steeper slopes, with high crown biomass and in climates with more water availability. In northern aspects solar radiation was lower and fuels had less water limitation to growth which, combined with steeper slopes, produced more extreme severity. In topographic fires there was more extreme severity in northern aspects with steeper slopes and in areas with more water availability and high crown biomass; in convection-dominated fires there was also more extreme fire severity in northern aspects with high biomass; while in wind-driven fires there was only a slight interaction between biomass and water availability. This latter pattern could be related to the fact that wind-driven fires spread with high wind speed, which could have minimized the effect of other variables. In the future, and as a consequence of climate change, new zones with high crown biomass accumulated in non-common drought areas will be available to burn

  8. Extreme Fire Severity Patterns in Topographic, Convective and Wind-Driven Historical Wildfires of Mediterranean Pine Forests

    Science.gov (United States)

    Lecina-Diaz, Judit; Alvarez, Albert; Retana, Javier

    2014-01-01

    Crown fires associated with extreme fire severity are extremely difficult to control. We have assessed fire severity using differenced Normalized Burn Ratio (dNBR) from Landsat imagery in 15 historical wildfires of Pinus halepensis Mill. We have considered a wide range of innovative topographic, fuel and fire behavior variables with the purposes of (1) determining the variables that influence fire severity patterns among fires (considering the 15 wildfires together) and (2) ascertaining whether different variables affect extreme fire severity within the three fire types (topographic, convective and wind-driven fires). The among-fires analysis showed that fires in less arid climates and with steeper slopes had more extreme severity. In less arid conditions there was more crown fuel accumulation and closer forest structures, promoting high vertical and horizontal fuel continuity and extreme fire severity. The analyses carried out for each fire separately (within fires) showed more extreme fire severity in areas in northern aspects, with steeper slopes, with high crown biomass and in climates with more water availability. In northern aspects solar radiation was lower and fuels had less water limitation to growth which, combined with steeper slopes, produced more extreme severity. In topographic fires there was more extreme severity in northern aspects with steeper slopes and in areas with more water availability and high crown biomass; in convection-dominated fires there was also more extreme fire severity in northern aspects with high biomass; while in wind-driven fires there was only a slight interaction between biomass and water availability. This latter pattern could be related to the fact that wind-driven fires spread with high wind speed, which could have minimized the effect of other variables. In the future, and as a consequence of climate change, new zones with high crown biomass accumulated in non-common drought areas will be available to burn as extreme

  9. Extreme fire severity patterns in topographic, convective and wind-driven historical wildfires of Mediterranean pine forests.

    Science.gov (United States)

    Lecina-Diaz, Judit; Alvarez, Albert; Retana, Javier

    2014-01-01

    Crown fires associated with extreme fire severity are extremely difficult to control. We have assessed fire severity using differenced Normalized Burn Ratio (dNBR) from Landsat imagery in 15 historical wildfires of Pinus halepensis Mill. We have considered a wide range of innovative topographic, fuel and fire behavior variables with the purposes of (1) determining the variables that influence fire severity patterns among fires (considering the 15 wildfires together) and (2) ascertaining whether different variables affect extreme fire severity within the three fire types (topographic, convective and wind-driven fires). The among-fires analysis showed that fires in less arid climates and with steeper slopes had more extreme severity. In less arid conditions there was more crown fuel accumulation and closer forest structures, promoting high vertical and horizontal fuel continuity and extreme fire severity. The analyses carried out for each fire separately (within fires) showed more extreme fire severity in areas in northern aspects, with steeper slopes, with high crown biomass and in climates with more water availability. In northern aspects solar radiation was lower and fuels had less water limitation to growth which, combined with steeper slopes, produced more extreme severity. In topographic fires there was more extreme severity in northern aspects with steeper slopes and in areas with more water availability and high crown biomass; in convection-dominated fires there was also more extreme fire severity in northern aspects with high biomass; while in wind-driven fires there was only a slight interaction between biomass and water availability. This latter pattern could be related to the fact that wind-driven fires spread with high wind speed, which could have minimized the effect of other variables. In the future, and as a consequence of climate change, new zones with high crown biomass accumulated in non-common drought areas will be available to burn as extreme

  10. Assessment of wind energy potential and cost estimation of wind-generated electricity at hilltops surrounding the city of Maroua in Cameroon

    Science.gov (United States)

    Kaoga, Dieudonné Kidmo; Bogno, Bachirou; Aillerie, Michel; Raidandi, Danwe; Yamigno, Serge Doka; Hamandjoda, Oumarou; Tibi, Beda

    2016-07-01

    In this work, 28 years of wind data, measured at 10m above ground level (AGL), from Maroua meteorological station is utilized to assess the potential of wind energy at exposed ridges tops of mountains surrounding the city of Maroua. The aim of this study is to estimate the cost of wind-generated electricity using six types of wind turbines (50 to 2000 kW). The Weibull distribution function is employed to estimate Weibull shape and scale parameters using the energy pattern factor method. The considered wind shear model to extrapolate Weibull parameters and wind profiles is the empirical power law correlation. The results show that hilltops in the range of 150-350m AGL in increments of 50, fall under Class 3 or greater of the international system of wind classification and are deemed suitable to outstanding for wind turbine applications. A performance of the selected wind turbines is examined as well as the costs of wind-generated electricity at the considered hilltops. The results establish that the lowest costs per kWh are obtained using YDF-1500-87 (1500 kW) turbine while the highest costs are delivered by P-25-100 (90 kW). The lowest costs (US) per kWh of electricity generated are found to vary between a minimum of 0.0294 at hilltops 350m AGL and a maximum of 0.0366 at hilltops 150m AGL, with corresponding energy outputs that are 6,125 and 4,932 MWh, respectively. Additionally, the matching capacity factors values are 38.05% at hilltops 150m AGL and 47.26% at hilltops 350m AGL. Furthermore, YDF-1500-87 followed by Enercon E82-2000 (2000 kW) wind turbines provide the lowest cost of wind generated electricity and are recommended for use for large communities. Medium wind turbine P-15-50 (50 kW), despite showing the best coefficients factors (39.29% and 48.85% at hilltops 150 and 350m AGL, in that order), generates electricity at an average higher cost/kWh of US0.0547 and 0.0440 at hilltops 150 and 350m AGL, respectively. P-15-50 is deemed a more advantageous option

  11. Wind-electric icemaking project: Analysis and dynamometer testing. Volume 1

    Energy Technology Data Exchange (ETDEWEB)

    Holz, R; Gervorgian, V; Drouilhet, S; Muljadi, E

    1998-07-01

    The wind/hybrid systems group at the National Renewable Energy Laboratory has been researching the most practical and cost-effective methods for producing ice from off-grid wind-electric power systems. The first phase of the project, conducted in 1993--1994, included full-scale dynamometer and field testing of two different electric ice makers directly connected to a permanent magnet alternator. The results of that phase were encouraging and the second phase of the project was launched in which steady-state and dynamic numerical models of these systems were developed and experimentally validated. The third phase of the project was the dynamometer testing of the North Star ice maker, which is powered by a 12-kilowatt Bergey Windpower Company, Inc., alternator. This report describes both the second and third project phases. Also included are detailed economic analyses and a discussion of the future prospects of wind-electric ice-making systems. The main report is contained in Volume 1. Volume 2 consists of the report appendices, which include the actual computer programs used in the analysis and the detailed test results.

  12. Design of an Electric Commutated Frog-Leg Winding Permanent-Magnet DC Machine

    Directory of Open Access Journals (Sweden)

    Hang Zhang

    2014-03-01

    Full Text Available An electric commutated frog-leg winding permanent-magnet (PM DC machine is proposed in this paper. It has a semi-closed slotted stator with a classical type of mesh winding introduced from the conventional brushed DC machine and a polyphase electric commutation besides a PM excitation rotor and a circular arrayed Hall position sensor. Under the cooperation between the position sensor and the electric commutation, the proposed machine is basically operated on the same principle of the brushed one. Because of its simplex frog-leg winding, the combination between poles and slots is designed as 4/22, and the number of phases is set as 11. By applying an exact analytical method, which is verified comparable with the finite element analyses (FEA, to the prediction of its instantaneous magnetic field, electromotive force (EMF, cogging torque and output torque, it is well designed with a series of parameters in dimension aiming at the lowest cogging torque. A 230 W, 4-pole, and 22-slot new machine is prototyped and tested to verify the analysis.

  13. Coping with wind power variability. How plug-in electric vehicles could help

    Energy Technology Data Exchange (ETDEWEB)

    Kiviluoma, Juha [Valtion Teknillinen Tutkimuskeskus, Espoo (Finland); Meibom, Peter [Technical Univ. of Denmark (DTU), Roskilde (Denmark). Risoe National Lab. for Sustainable Energy

    2009-07-01

    Plug-in electric vehicles could offer flexibility for wind power and an attempt was made to quantify the effect with a power system model Wilmar. Wilmar simulates unit commitment and dispatch using mixed integer programming and includes wind power and load stochasticity as well as a module for plug-in electric vehicles. Forecast errors of wind power increase the need for balancing and ancillary services. The model is able to use the plug-in electric vehicles (PHEVs) to participate in the balancing and ancillary services and decrease the costs of these services. The charging and possible discharging of the vehicles can also be optimized to most beneficial hours within the limits caused by vehicle use. We have calculated the benefits at different PHEV penetration levels. The results indicate that benefits of peak shaving using vehicle to grid are limited due to the rather small size of storage in the batteries even with a large number of vehicles. Benefits can best be seen in the smart charging of the vehicles and in the correction of forecast errors. The marginal benefits of introducing PHEVs capable of smart charging and discharging are high for low numbers of PHEVs in the power system, but declines with higher penetration levels of PHEVs, because the demands for power system reserves and flexibility are limited. (orig.)

  14. Large eddy simulation of fire-induced buoyancy driven plume dispersion in an urban street canyon under perpendicular wind flow.

    Science.gov (United States)

    Hu, L H; Huo, R; Yang, D

    2009-07-15

    The dispersion of fire-induced buoyancy driven plume in and above an idealized street canyon of 18 m (width) x 18 m (height) x 40 m (length) with a wind flow perpendicular to its axis was investigated by Fire Dynamics Simulator (FDS), Large Eddy Simulation (LES). Former studies, such as that by Oka [T.R. Oke, Street design and urban canopy layer climate, Energy Build. 11 (1988) 103-113], Gayev and Savory [Y.A. Gayev, E. Savory, Influence of street obstructions on flow processes within street canyons. J. Wind Eng. Ind. Aerodyn. 82 (1999) 89-103], Xie et al. [S. Xie, Y. Zhang, L. Qi, X. Tang, Spatial distribution of traffic-related pollutant concentrations in street canyons. Atmos. Environ. 37 (2003) 3213-3224], Baker et al. [J. Baker, H. L. Walker, X. M. Cai, A study of the dispersion and transport of reactive pollutants in and above street canyons--a large eddy simulation, Atmos. Environ. 38 (2004) 6883-6892] and Baik et al. [J.-J. Baik, Y.-S. Kang, J.-J. Kim, Modeling reactive pollutant dispersion in an urban street canyon, Atmos. Environ. 41 (2007) 934-949], focus on the flow pattern and pollutant dispersion in the street canyon with no buoyancy effect. Results showed that with the increase of the wind flow velocity, the dispersion pattern of a buoyant plume fell into four regimes. When the wind flow velocity increased up to a certain critical level, the buoyancy driven upward rising plume was re-entrained back into the street canyon. This is a dangerous situation as the harmful fire smoke will accumulate to pollute the environment and thus threaten the safety of the people in the street canyon. This critical re-entrainment wind velocity, as an important parameter to be concerned, was further revealed to increase asymptotically with the heat/buoyancy release rate of the fire.

  15. Experimental and Numerical Analysis of Wind Driven Natural Ventilation in a Building Scale Model

    DEFF Research Database (Denmark)

    Heiselberg, Per Kvols; True, Jan Per Jensen; Sandberg, Mats

    2004-01-01

    Airflow through openings in a cross ventilated building scale model was investigated in a wind tunnel and by numerical predictions. Predictions for a wind direction perpendicular to the building showed an airflow pattern consisting of streamlines entering the room, that originated from approximat......Airflow through openings in a cross ventilated building scale model was investigated in a wind tunnel and by numerical predictions. Predictions for a wind direction perpendicular to the building showed an airflow pattern consisting of streamlines entering the room, that originated from...... and leeward sides and the airflow rate was found to be a linear function of the local pressure difference across the building....

  16. Wind power development in the United States: Effects of policies and electricity transmission congestion

    Science.gov (United States)

    Hitaj, Claudia

    In this dissertation, I analyze the drivers of wind power development in the United States as well as the relationship between renewable power plant location and transmission congestion and emissions levels. I first examine the role of government renewable energy incentives and access to the electricity grid on investment in wind power plants across counties from 1998-2007. The results indicate that the federal production tax credit, state-level sales tax credit and production incentives play an important role in promoting wind power. In addition, higher wind power penetration levels can be achieved by bringing more parts of the electricity transmission grid under independent system operator regulation. I conclude that state and federal government policies play a significant role in wind power development both by providing financial support and by improving physical and procedural access to the electricity grid. Second, I examine the effect of renewable power plant location on electricity transmission congestion levels and system-wide emissions levels in a theoretical model and a simulation study. A new renewable plant takes the effect of congestion on its own output into account, but ignores the effect of its marginal contribution to congestion on output from existing plants, which results in curtailment of renewable power. Though pricing congestion removes the externality and reduces curtailment, I find that in the absence of a price on emissions, pricing congestion may in some cases actually increase system-wide emissions. The final part of my dissertation deals with an econometric issue that emerged from the empirical analysis of the drivers of wind power. I study the effect of the degree of censoring on random-effects Tobit estimates in finite sample with a particular focus on severe censoring, when the percentage of uncensored observations reaches 1 to 5 percent. The results show that the Tobit model performs well even at 5 percent uncensored observations

  17. Integrated analysis of DFIG drive-train and power electronics dynamics during electrical AC faults and wind disturbances

    DEFF Research Database (Denmark)

    Barahona Garzón, Braulio; Sørensen, Poul Ejnar; Anaya-Lara, Olimpo

    2013-01-01

    The dynamics of a 2 MW DFIG wind turbine are studied during electrical AC faults, and wind disturbances. A simulation platform that couples HAWC2, and Matlab/Simulink was used. High frequencies of the gear box, and power electronics are neglected. It was shown that the dynamics of the dc...

  18. QUANTIFICATION AND COSTING OF DOMESTIC ELECTRICITY GENERATION FOR ARMIDALE, NEW SOUTH WALES, AUSTRALIA UTILISING MICRO WIND TURBINES

    Directory of Open Access Journals (Sweden)

    Yasser Maklad

    2014-04-01

    Full Text Available In this study, a general overview of energy and renewable energy sources available in Australia was introduced, household’s electricity situation in Australia was presented, and focus wind energy was conducted. A theoretical methodology for quantification and costing of selected micro wind turbines was introduced. This methodology was applied to Armidale city, New South Wales (NSW, Australia as a case study. The methodology involved utilisation of spread sheet application and HOMER software. Such methodology dealt with hourly household electric load in Armidale and hourly wind speed in Armidale as inputs and provided hourly power outputs from selected micro wind turbine as an output. As well, a sample of payback period calculations for the said selected wind turbines is calculated versus various wind speeds. This methodology can be applied to any other cities or towns. Undoubtedly, the ability of quantifying micro electricity generation resultant from micro wind turbines for a specific city or town and evaluating the share of households’ electric consumption at that city or town associated with the relevant payback periods opens the gate for further studies of feasibility and visibility of micro wind turbines.

  19. Efficacy of brain-computer interface-driven neuromuscular electrical stimulation for chronic paresis after stroke.

    Science.gov (United States)

    Mukaino, Masahiko; Ono, Takashi; Shindo, Keiichiro; Fujiwara, Toshiyuki; Ota, Tetsuo; Kimura, Akio; Liu, Meigen; Ushiba, Junichi

    2014-04-01

    Brain computer interface technology is of great interest to researchers as a potential therapeutic measure for people with severe neurological disorders. The aim of this study was to examine the efficacy of brain computer interface, by comparing conventional neuromuscular electrical stimulation and brain computer interface-driven neuromuscular electrical stimulation, using an A-B-A-B withdrawal single-subject design. A 38-year-old male with severe hemiplegia due to a putaminal haemorrhage participated in this study. The design involved 2 epochs. In epoch A, the patient attempted to open his fingers during the application of neuromuscular electrical stimulation, irrespective of his actual brain activity. In epoch B, neuromuscular electrical stimulation was applied only when a significant motor-related cortical potential was observed in the electroencephalogram. The subject initially showed diffuse functional magnetic resonance imaging activation and small electro-encephalogram responses while attempting finger movement. Epoch A was associated with few neurological or clinical signs of improvement. Epoch B, with a brain computer interface, was associated with marked lateralization of electroencephalogram (EEG) and blood oxygenation level dependent responses. Voluntary electromyogram (EMG) activity, with significant EEG-EMG coherence, was also prompted. Clinical improvement in upper-extremity function and muscle tone was observed. These results indicate that self-directed training with a brain computer interface may induce activity- dependent cortical plasticity and promote functional recovery. This preliminary clinical investigation encourages further research using a controlled design.

  20. A double-strip plasmonic waveguide coupled to an electrically driven nanowire LED.

    Science.gov (United States)

    No, You-Shin; Choi, Jae-Hyuck; Ee, Ho-Seok; Hwang, Min-Soo; Jeong, Kwang-Yong; Lee, Eun-Khwang; Seo, Min-Kyo; Kwon, Soon-Hong; Park, Hong-Gyu

    2013-02-13

    We demonstrate the efficient integration of an electrically driven nanowire (NW) light source with a double-strip plasmonic waveguide. A top-down-fabricated GaAs NW light-emitting diode (LED) is placed between two straight gold strip waveguides with the gap distance decreasing to 30 nm at the end of the waveguide and operated by current injection through the p-contact electrode acting as a plasmonic waveguide. Measurements of polarization-resolved images and spectra show that the light emission from the NW LED was coupled to a plasmonic waveguide mode, propagated through the waveguide, and was focused onto a subwavelength-sized spot of surface plasmon polaritons at the tapered end of the waveguide. Numerical simulation agreed well with these experimental results, confirming that a symmetric plasmonic waveguide mode was excited on the top surface of the waveguide. Our demonstration of a plasmonic waveguide coupled to an electrically driven NW LED represents important progress toward further miniaturization and practical implementation of ultracompact photonic integrated circuits.

  1. Enhancement of survival and electricity production in an engineered bacterium by light-driven proton pumping.

    Science.gov (United States)

    Johnson, Ethan T; Baron, Daniel B; Naranjo, Belén; Bond, Daniel R; Schmidt-Dannert, Claudia; Gralnick, Jeffrey A

    2010-07-01

    Microorganisms can use complex photosystems or light-dependent proton pumps to generate membrane potential and/or reduce electron carriers to support growth. The discovery that proteorhodopsin is a light-dependent proton pump that can be expressed readily in recombinant bacteria enables development of new strategies to probe microbial physiology and to engineer microbes with new light-driven properties. Here, we describe functional expression of proteorhodopsin and light-induced changes in membrane potential in the bacterium Shewanella oneidensis strain MR-1. We report that there were significant increases in electrical current generation during illumination of electrochemical chambers containing S. oneidensis expressing proteorhodopsin. We present evidence that an engineered strain is able to consume lactate at an increased rate when it is illuminated, which is consistent with the hypothesis that proteorhodopsin activity enhances lactate uptake by increasing the proton motive force. Our results demonstrate that there is coupling of a light-driven process to electricity generation in a nonphotosynthetic engineered bacterium. Expression of proteorhodopsin also preserved the viability of the bacterium under nutrient-limited conditions, providing evidence that fulfillment of basic energy needs of organisms may explain the widespread distribution of proteorhodopsin in marine environments.

  2. Projected changes of the low-latitude north-western Pacific wind-driven circulation under global warming

    Science.gov (United States)

    Duan, Jing; Chen, Zhaohui; Wu, Lixin

    2017-05-01

    Based on the outputs of 25 models participating in the Coupled Model Intercomparison Project Phase 5, the projected changes of the wind-driven circulation in the low-latitude north-western Pacific are evaluated. Results demonstrate that there will be a decrease in the mean transport of the North Equatorial Current (NEC), Mindanao Current, and Kuroshio Current in the east of the Philippines, accompanied by a northward shift of the NEC bifurcation Latitude (NBL) off the Philippine coast with over 30% increase in its seasonal south-north migration amplitude. Numerical simulations using a 1.5-layer nonlinear reduced-gravity ocean model show that the projected changes of the upper ocean circulation are predominantly determined by the robust weakening of the north-easterly trade winds and the associated wind stress curl under the El Niño-like warming pattern. The changes in the wind forcing and intensified upper ocean stratification are found equally important in amplifying the seasonal migration of the NBL.

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

    Science.gov (United States)

    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

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

    Directory of Open Access Journals (Sweden)

    Senad Apelfröjd

    2014-01-01

    Full Text Available 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.

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

    Science.gov (United States)

    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.

  6. Electric vehicles. From wind-powered vehicles to electric cars; Elektrofahrzeuge. Vom Windwagen zum Elektromobil

    Energy Technology Data Exchange (ETDEWEB)

    Kloss, A.

    1996-12-31

    The electric car can be viewed as the car of the future, and intensive development efforts are currently being made. The book presents technical and historical background knowledge for the expert and the layman. Starting with the invention of the wheel cart 5000 years ago, it covers the period of steam-powered cars in the 19th century and ends with the first boom of electric cars at the turn of the century. It goes into detail about the development of the electric motor, the battery and the accumulator battery, and the railbound electric road vehicles and hybrid vehicles. Moon vehicles and solar mobiles get a mention as well. The current situation is analyzed, and trends for the future are pointed out. (orig.) [Deutsch] Das Elektromobil kann mittel- und langfristig als das Auto der Zukunft betrachtet werden. An seiner Entwicklung wird weltweit intensiv gearbeitet. Die Aufgabe des Buchs ist es, dem Fachmann und dem interessierten Laien zur Problematik des Elektroautos ein fundiertes technisch-historisches Hintergrundwissen zu vermitteln. Der historische Bogen, den hier der Autor ueber den elektrischen Strassenverkehr spannt, beginnt mit der Erfindung des Wagens vor 5 000 Jahren, umfasst die Periode der Dampfwagentechnik des 19. Jh. und endet mit der Bluetezeit der ersten Generation des Elektromobils an der Jahrhundertwende. Behandelt werden sowohl die Entwicklung des Elektromotors, der Batterie und des Akkumulators als auch der schienengebundenen elektrischen Strassenfahrzeuge und der Hybridwagen bis in die neueste Zeit. Aber auch Mondautos und Solarmobile kommen zur Sprache. Anhand der Analyse des heutigen Entwicklungsstands werden Zukunftaussichten aufzeigt. (orig.)

  7. Advanced control of direct-driven PMSG generator in wind turbine system

    Directory of Open Access Journals (Sweden)

    Gajewski Piotr

    2016-12-01

    Full Text Available The paper presents the advanced control system of the wind energy conversion with a variable speed wind turbine. The considered system consists of a wind turbine with the permanent magnet synchronous generator (PMSG, machine side converter (MSC, grid side converter (GSC and control circuits. The mathematical models of a wind turbine system, the PMSG generator and converters have been described. The control algorithms of the converter systems based on the methods of vector control have been applied. In the advanced control system of the machine side converter the optimal MPPT control method has been used. Additionally the pitch control scheme is included in order to achieve the limitation of maximum power and to prevent mechanical damage of the wind turbine. In the control system of the grid side converter the control of active and reactive power has been applied with the application of Voltage Oriented Control (VOC. The performance of the considered wind energy system has been studied by digital simulation. The results of simulation studies confirmed the good effectiveness of the considered wind turbine system and very good performance of the proposed methods of vector control and control systems.

  8. The intermittency of wind, solar, and renewable electricity generators. Technical barrier or rhetorical excuse?

    Energy Technology Data Exchange (ETDEWEB)

    Sovacool, Benjamin K. [Centre on Asia and Globalisation, Lee Kuan Yew School of Public Policy, National University of Singapore, 469C Bukit Timah Road, Singapore 259772 (Singapore)

    2009-09-15

    A consensus has long existed within the electric utility sector of the United States that renewable electricity generators such as wind and solar are unreliable and intermittent to a degree that they will never be able to contribute significantly to electric utility supply or provide baseload power. This paper asks three interconnected questions: (1) What do energy experts really think about renewables in the United States?; (2) To what degree are conventional baseload units reliable?; (3) Is intermittency a justifiable reason to reject renewable electricity resources? To provide at least a few answers, the author conducted 62 formal, semi-structured interviews at 45 different institutions including electric utilities, regulatory agencies, interest groups, energy systems manufacturers, nonprofit organizations, energy consulting firms, universities, national laboratories, and state institutions in the United States. In addition, an extensive literature review of government reports, technical briefs, and journal articles was conducted to understand how other countries have dealt with (or failed to deal with) the intermittent nature of renewable resources around the world. It was concluded that the intermittency of renewables can be predicted, managed, and mitigated, and that the current technical barriers are mainly due to the social, political, and practical inertia of the traditional electricity generation system. (author)

  9. Experimental and analytical research on the aerodynamics of wind driven turbines. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Rohrbach, C.; Wainauski, H.; Worobel, R.

    1977-12-01

    This aerodynamic research program was aimed at providing a reliable, comprehensive data base on a series of wind turbine models covering a broad range of the prime aerodynamic and geometric variables. Such data obtained under controlled laboratory conditions on turbines designed by the same method, of the same size, and tested in the same wind tunnel had not been available in the literature. Moreover, this research program was further aimed at providing a basis for evaluating the adequacy of existing wind turbine aerodynamic design and performance methodology, for assessing the potential of recent advanced theories and for providing a basis for further method development and refinement.

  10. Wind energy for electricity generation; Generacion electrica con energia del viento

    Energy Technology Data Exchange (ETDEWEB)

    Huacuz Villamar, Jorge M.; Borja Diaz, Marco Antonio R. [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1998-09-01

    A description is made of electricity generation utilizing wind energy (Eoloelectric Generation). The case of Mexico is reviewed in respect to this technology, mentioning a small power plant of 1.5 Megawatts installed by the Comision Federal de Electricidad in the zone of La Ventosa in the State of Oaxaca. Mention is made of the possible causes why Mexico has not advanced in this type of power plants for power generation as in other countries like Germany, Spain and India. The advance in these countries is shown as well as the growth statistics of the wind power in the world. It is concluded that there is not in Mexico a strategy for wind energy utilization for electricity generation in spite of the potential benefits this technology offers [Espanol] Se describe el caso de la generacion electrica utilizando la energia del viento (Generacion Eoloelectrica). Se aborda el caso de Mexico respecto a esta tecnologia, mencionando una pequena central de 1.5 Megawatts (MW) instalada por la Comision Federal de Electricidad (CFE) en la zona de la Ventosa, Oaxaca. Se mencionan las posibles causas por las que en Mexico este tipo de centrales de generacion de energia no ha avanzado como en otros paises, por ejemplo: Alemania, Espana y la India. Se muestran los avances de estos paises, asi como una estadistica del crecimiento de la generacion eoloelectrica en el mundo. Se concluye en que no existe en Mexico una estrategia para la generacion eoloelectrica a pesar de los beneficios potenciales que ofrece esta tecnologia

  11. Wind Power Development and Energy Storage under China’s Electricity Market Reform—A Case Study of Fujian Province

    Directory of Open Access Journals (Sweden)

    Dunguo Mou

    2018-01-01

    Full Text Available This paper, based on the Fujian provincial 500 kV grid and part of the 220 kV grid and the key power plants, including hydro, coal, nuclear, gas, wind and pumping and storage hydro powers (PSHP connected to the grid, constructs an independent electricity market model. Using data that are very close to reality about coal fired power production costs, along with data about power plants’ technical constraints, this paper studies the effect of wind power on Fujian’s provincial electricity market. Firstly, the paper analyzes the relationship between wind speed and wind power output and the effects of short-term power output fluctuation on frequency modulation and voltage regulation. Secondly, under supposition of the production costs following quadratic functions, the paper analyzes the effects of changes in wind power output on the electricity supply costs under optimal power flow. Thirdly, using the bidding model in the Australian Electricity Market Operator for reference and supposing that, in a competitive market, coal fired power plants can bid 6 price bands according to their capacity, the paper analyzes effects of wind power on electricity prices under optimal power flow, the stabilizing effects of PSHP and the minimum PSHP capacity needed to stabilize the electricity market. Finally, using a daily load curve, this paper simulates the electricity prices’ fluctuation under optimal power flow and PSHP’s stabilizing effect. The results show that, although PSHP has a large external social welfare effect, it can hardly make a profit. In the end, this paper puts forward some policy suggestions for Fujian province’s wind and nuclear power development, PSHP construction and electricity market development.

  12. Permanent Magnet Synchronous Generator Driven Wind Energy Conversion System Based on Parallel Active Power Filter

    Directory of Open Access Journals (Sweden)

    FERDI Brahim

    2014-05-01

    Full Text Available This paper proposes a novel application of the instantaneous P-Q theory in a wind energy conversion system (WECS. The proposed WECS is formed by permanent magnet synchronous generator (PMSG wind turbine system connected to the grid through parallel active power filter (PAPF. PAPF uses the generated wind energy to feed loads connected at the point of common coupling (PPC, compensates current harmonics and injects the excess of this energy into the grid using P-Q theory as control method. To demonstrate the feasibility and the performance of the proposed control scheme, simulation of this wind system has been realized using MATLAB/SIMULINK software. Simulation results show the accuracy and validity of the proposed control scheme for the PMSGPAPF system.

  13. Experimental and analytical research on the aerodynamics of wind driven turbines. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Rohrbach, C.; Wainauski, H.; Worobel, R.

    1977-12-01

    The successful development of reliable, cost competitive horizontal axis, propeller-type wind energy conversion systems (WECS) is strongly dependent on the availability of advanced technology for each of the system components. This aerodynamic research program was aimed at providing a reliable, comprehensive data base on a series of wind turbine models covering a broad range of the prime aerodynamic and geometric variables. Such data obtained under controlled laboratory conditions on turbines designed by the same method, of the same size, and tested in the same wind tunnel had not been available in the literature. Moreover, this research program was further aimed at providing a basis for evaluating the adequacy of existing wind turbine aerodynamic design and performance methodology, for assessing the potential of recent advanced theories and for providing a basis for further method development and refinement.

  14. Method for selecting parameters and assessing efficiency of wind-diesel power plants for autonomous electrical supply systems

    Science.gov (United States)

    Obukhov, S. G.; Plotnikov, I. A.; Masolov, V. G.

    2018-01-01

    The article presents an original technique for selecting parameters and evaluating the efficiency of wind-diesel power plants for isolated power supply systems. The initial data to perform energy calculations are simulation models of electric load and wind speed. The load is simulated using typical schedules of electric loads of a decentralized consumer, taking into account a random component for each hour of the day. To create a simulation model of the wind, a typical climatic series of wind speeds at a prospective site of the power plant has been constructed according to the data of long-term meteorological observations. The proposed technique was verified through the example of choosing a wind-diesel power plant for the village of Ust-Olenyok of the Republic of Sakha (Yakutia).

  15. Stratified magnetically driven accretion-disk winds and their relations to jets

    Energy Technology Data Exchange (ETDEWEB)

    Fukumura, Keigo [University of Maryland, Baltimore County (UMBC/CRESST), Baltimore, MD 21250 (United States); Tombesi, Francesco; Kazanas, Demosthenes; Shrader, Chris [Astrophysics Science Division, NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Behar, Ehud [Department of Physics, Technion, Haifa 32000 (Israel); Contopoulos, Ioannis, E-mail: fukumukx@jmu.edu [Research Center for Astronomy, Academy of Athens, Athens 11527 (Greece)

    2014-01-10

    We explore the poloidal structure of two-dimensional magnetohydrodynamic (MHD) winds in relation to their potential association with the X-ray warm absorbers (WAs) and the highly ionized ultra-fast outflows (UFOs) in active galactic nuclei (AGNs), in a single unifying approach. We present the density n(r, θ), ionization parameter ξ(r, θ), and velocity structure v(r, θ) of such ionized winds for typical values of their fluid-to-magnetic flux ratio, F, and specific angular momentum, H, for which wind solutions become super-Alfvénic. We explore the geometrical shape of winds for different values of these parameters and delineate the values that produce the widest and narrowest opening angles of these winds, quantities necessary in the determination of the statistics of AGN obscuration. We find that winds with smaller H show a poloidal geometry of narrower opening angles with their Alfvén surface at lower inclination angles and therefore they produce the highest line of sight (LoS) velocities for observers at higher latitudes with the respect to the disk plane. We further note a physical and spatial correlation between the X-ray WAs and UFOs that form along the same LoS to the observer but at different radii, r, and distinct values of n, ξ, and v consistent with the latest spectroscopic data of radio-quiet Seyfert galaxies. We also show that, at least in the case of 3C 111, the winds' pressure is sufficient to contain the relativistic plasma responsible for its radio emission. Stratified MHD disk winds could therefore serve as a unique means to understand and unify the diverse AGN outflows.

  16. Stratified Magnetically Driven Accretion-Disk Winds and Their Relations To Jets

    Science.gov (United States)

    Fukumura, Keigo; Tombesi, Francesco; Kazanas, Demosthenes; Shrader, Chris; Behar, Ehud; Contopoulos, Ioannis

    2013-01-01

    We explore the poloidal structure of two-dimensional magnetohydrodynamic (MHD) winds in relation to their potential association with the X-ray warm absorbers (WAs) and the highly ionized ultra-fast outflows (UFOs) in active galactic nuclei (AGNs), in a single unifying approach. We present the density n(r, theta), ionization parameter xi(r, theta), and velocity structure v(r, theta) of such ionized winds for typical values of their fluid-to-magnetic flux ratio, F, and specific angular momentum, H, for which wind solutions become super-Alfvenic. We explore the geometrical shape of winds for different values of these parameters and delineate the values that produce the widest and narrowest opening angles of these winds, quantities necessary in the determination of the statistics of AGN obscuration. We find that winds with smaller H show a poloidal geometry of narrower opening angles with their Alfv´en surface at lower inclination angles and therefore they produce the highest line of sight (LoS) velocities for observers at higher latitudes with the respect to the disk plane. We further note a physical and spatial correlation between the X-ray WAs and UFOs that form along the same LoS to the observer but at different radii, r, and distinct values of n, xi, and v consistent with the latest spectroscopic data of radio-quiet Seyfert galaxies. We also show that, at least in the case of 3C 111, the winds' pressure is sufficient to contain the relativistic plasma responsible for its radio emission. Stratified MHD disk winds could therefore serve as a unique means to understand and unify the diverse AGN outflows.

  17. Investigation on electrically-driven semiconductor-metal transition of polycrystalline VO2 thin films on two kinds of substrates

    Directory of Open Access Journals (Sweden)

    Deen Gu

    2018-01-01

    Full Text Available Electrical driving is one of frequently-used stimuli for the semiconductor-metal transition (SMT of VO2. But the driving mechanism is still under debate. We investigated the DC electrically-driven SMT features of polycrystalline VO2 thin films deposited on two kinds of substrates (quartz and silicon with obviously-different thermal conductivity and the influence of cooling by a thermo electric cooler (TEC on the SMT of VO2. Interestingly, the SMT doesn’t happen at a high voltage at very start, but at a relatively low one. Moreover, the SMT of VO2 thin films on silicon substrate is completely restrained by cooling through a TEC although the electric field strength across VO2 reaches 1.1×107 V/m. Our findings reveal that the Joule-heating effect plays an important role in the DC electrically-driven SMT of VO2.

  18. A Comparative Analysis of Energy Costs of Photovoltaic, Solar Thermal, and Wind Electricity Generation Technologies

    Directory of Open Access Journals (Sweden)

    Michael Dale

    2013-03-01

    Full Text Available Global installed capacity of renewable energy technologies is growing rapidly. The ability of renewable technologies to enable a rapid transition to a low carbon energy system is highly dependent on the energy that must be “consumed” during their life-cycle. This paper presents the results of meta-analyses of life-cycle assessments (LCA of energy costs of three renewable technologies: solar photovoltaic (PV, concentrating solar power (CSP, and wind. The paper presents these findings as energetic analogies with financial cost parameters for assessing energy technologies: overnight capital cost, operating costs and levelized cost of electricity (LCOE. The findings suggest that wind energy has the lowest energy costs, followed by CSP and then PV.

  19. Electric-field-driven domain wall dynamics in perpendicularly magnetized multilayers

    Directory of Open Access Journals (Sweden)

    Diego López González

    2017-03-01

    Full Text Available We report on reversible electric-field-driven magnetic domain wall motion in a Cu/Ni multilayer on a ferroelectric BaTiO3 substrate. In our heterostructure, strain-coupling to ferroelastic domains with in-plane and perpendicular polarization in the BaTiO3 substrate causes the formation of domains with perpendicular and in-plane magnetic anisotropy, respectively, in the Cu/Ni multilayer. Walls that separate magnetic domains are elastically pinned onto ferroelectric domain walls. Using magneto-optical Kerr effect microscopy, we demonstrate that out-of-plane electric field pulses across the BaTiO3 substrate move the magnetic and ferroelectric domain walls in unison. Our experiments indicate an exponential increase of domain wall velocity with electric field strength and opposite domain wall motion for positive and negative field pulses. The application of a magnetic field does not affect the velocity of magnetic domain walls, but independently tailors their internal spin structure, causing a change in domain wall dynamics at high velocities.

  20. Single-Cell Electric Lysis on an Electroosmotic-Driven Microfluidic Chip with Arrays of Microwells

    Directory of Open Access Journals (Sweden)

    Yu-Hung Chen

    2012-05-01

    Full Text Available Accurate analysis at the single-cell level has become a highly attractive tool for investigating cellular content. An electroosmotic-driven microfluidic chip with arrays of 30-µm-diameter microwells was developed for single-cell electric lysis in the present study. The cellular occupancy in the microwells when the applied voltage was 5 V (82.4% was slightly higher than that at an applied voltage of 10 V (81.8%. When the applied voltage was increased to 15 V, the cellular occupancy in the microwells dropped to 64.3%. More than 50% of the occupied microwells contain individual cells. The results of electric lysis experiments at the single-cell level indicate that the cells were gradually lysed as the DC voltage of 30 V was applied; the cell was fully lysed after 25 s. Single-cell electric lysis was demonstrated in the proposed microfluidic chip, which is suitable for high-throughput cell lysis.

  1. Flow instability in laminar jet flames driven by alternating current electric fields

    KAUST Repository

    Kim, Gyeong Taek

    2016-10-13

    The effect of electric fields on the instability of laminar nonpremixed jet flames was investigated experimentally by applying the alternating current (AC) to a jet nozzle. We aimed to elucidate the origin of the occurrence of twin-lifted jet flames in laminar jet flow configurations, which occurred when AC electric fields were applied. The results indicated that a twin-lifted jet flame originated from cold jet instability, caused by interactions between negative ions in the jet flow via electron attachment as O +e→O when AC electric fields were applied. This was confirmed by conducting systematic, parametric experiment, which included changing gaseous component in jets and applying different polarity of direct current (DC) to the nozzle. Using two deflection plates installed in parallel with the jet stream, we found that only negative DC on the nozzle could charge oxygen molecules negatively. Meanwhile, the cold jet instability occurred only for oxygen-containing jets. A shedding frequency of jet stream due to AC driven instability showed a good correlation with applied AC frequency exhibiting a frequency doubling. However, for the applied AC frequencies over 80Hz, the jet did not respond to the AC, indicating an existence of a minimum flow induction time in a dynamic response of negative ions to external AC fields. Detailed regime of the instability in terms of jet velocity, AC voltage and frequency was presented and discussed. Hypothesized mechanism to explain the instability was also proposed.

  2. Electrifying white biotechnology: engineering and economic potential of electricity-driven bio-production.

    Science.gov (United States)

    Harnisch, Falk; Rosa, Luis F M; Kracke, Frauke; Virdis, Bernardino; Krömer, Jens O

    2015-03-01

    The production of fuels and chemicals by electricity-driven bio-production (i.e., using electric energy to drive biosynthesis) holds great promises. However, this electrification of white biotechnology is particularly challenging to achieve because of the different optimal operating conditions of electrochemical and biochemical reactions. In this article, we address the technical parameters and obstacles to be taken into account when engineering microbial bioelectrochemical systems (BES) for bio-production. In addition, BES-based bio-production processes reported in the literature are compared against industrial needs showing that a still large gap has to be closed. Finally, the feasibility of BES bio-production is analysed based on bulk electricity prices. Using the example of lysine production from sucrose, we demonstrate that there is a realistic market potential as cost savings of 8.4 % (in EU) and 18.0 % (in US) could be anticipated, if the necessary yields can be obtained. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. A fuzzy chance-constrained program for unit commitment problem considering demand response, electric vehicle and wind power

    DEFF Research Database (Denmark)

    Zhang, Ning; Hu, Zhaoguang; Han, Xue

    2015-01-01

    commitment model is proposed in this paper considering demand response and electric vehicles, which can promote the exploitation of wind power. On the one hand, demand response and electric vehicles have the feasi- bility to change the load demand curve to solve the mismatch problem. On the other hand...... system operation more eco-friendly and economical....

  4. Remote Sensing Marine Ecology: Wind-driven algal blooms in the open oceans and their ecological impacts

    Science.gov (United States)

    Tang, DanLing

    2016-07-01

    Algal bloom not only can increase the primary production but also could result in negative ecological consequence, e.g., Harmful Algal Blooms (HABs). According to the classic theory for the formation of algal blooms "critical depth" and "eutrophication", oligotrophic sea area is usually difficult to form a large area of algal blooms, and actually the traditional observation is only sporadic capture to the existence of algal blooms. Taking full advantage of multiple data of satellite remote sensing, this study: 1), introduces "Wind-driven algal blooms in open oceans: observation and mechanisms" It explained except classic coastal Ekman transport, the wind through a variety of mechanisms affecting the formation of algal blooms. Proposed a conceptual model of "Strong wind -upwelling-nutrient-phytoplankton blooms" in Western South China Sea (SCS) to assess role of wind-induced advection transport in phytoplankton bloom formation. It illustrates the nutrient resources that support long-term offshore phytoplankton blooms in the western SCS; 2), Proposal of the theory that "typhoons cause vertical mixing, induce phytoplankton blooms", and quantify their important contribution to marine primary production; Proposal a new ecological index for typhoon. Proposed remote sensing inversion models. 3), Finding of the spatial and temporaldistributions pattern of harmful algal bloom (HAB)and species variations of HAB in the South Yellow Sea and East China Sea, and in the Pearl River estuary, and their oceanic dynamic mechanisms related with monsoon; The project developed new techniques and generated new knowledge, which significantly improved understanding of the formation mechanisms of algal blooms. 1), It proposed "wind-pump" mechanism integrates theoretical system combing "ocean dynamics, development of algal blooms, and impact on primary production", which will benefit fisheries management. 2), A new interdisciplinary subject "Remote Sensing Marine Ecology"(RSME) has been

  5. Real-Time Tariffs for Electric Vehicles in Wind Power based Power Systems

    DEFF Research Database (Denmark)

    Morais, Hugo; Sousa, Tiago; Silva, Marco

    2013-01-01

    The use of Electric Vehicles (EVs) will change significantly the planning and management of power systems in a near future. This paper proposes a real-time tariff strategy for the charge process of the EVs. The main objective is to evaluate the influence of real-time tariffs in the EVs owners......’ behaviour and also the impact in load diagram. The paper proposes the energy price variation according to the relation between wind generation and power consumption. The proposed strategy was tested in two different days in the Danish power system. January 31st and August 13th 2013 were selected because...

  6. Thrust calculation of electric solar wind sail by particle-in-cell simulation

    Energy Technology Data Exchange (ETDEWEB)

    Hoshi, Kento [Kyoto Univ. (Japan). Dept. of Electrical Engineering; Kojima, Hirotsugu; Yamakawa, Hiroshi [Kyoto Univ. (Japan). Research Inst. for Sustainable Humanosphere; Muranaka, Takanobu [Chukyo Univ., Nagoya (Japan). Dept. of Electrical Engineering

    2016-07-01

    In this study, thrust characteristics of an electric solar wind sail were numerically evaluated using full threedimensional particle-in-cell (PIC) simulation. The thrust obtained from the PIC simulation was lower than the thrust estimations obtained in previous studies. The PIC simulation indicated that ambient electrons strongly shield the electrostatic potential of the tether of the sail, and the strong shield effect causes a greater thrust reduction than has been obtained in previous studies. Additionally, previous expressions of the thrust estimation were modified by using the shielded potential structure derived from the present simulation results. The modified thrust estimation agreed very well with the thrust obtained from the PIC simulation.

  7. Noise Model Analysis and Estimation of Effect due to Wind Driven Ambient Noise in Shallow Water

    Directory of Open Access Journals (Sweden)

    S. Sakthivel Murugan

    2011-01-01

    Full Text Available Signal transmission in ocean using water as a channel is a challenging process due to attenuation, spreading, reverberation, absorption, and so forth, apart from the contribution of acoustic signals due to ambient noises. Ambient noises in sea are of two types: manmade (shipping, aircraft over the sea, motor on boat, etc. and natural (rain, wind, seismic, etc., apart from marine mammals and phytoplanktons. Since wind exists in all places and at all time: its effect plays a major role. Hence, in this paper, we concentrate on estimating the effects of wind. Seven sets of data with various wind speeds ranging from 2.11 m/s to 6.57 m/s were used. The analysis is performed for frequencies ranging from 100 Hz to 8 kHz. It is found that a linear relationship between noise spectrum and wind speed exists for the entire frequency range. Further, we developed a noise model for analyzing the noise level. The results of the empirical data are found to fit with results obtained with the aid of noise model.

  8. Wind increase over cooling Southern Ocean driven by tropical warming and polar ozone hole

    Science.gov (United States)

    Schneider, D. P.; Fan, T.; Deser, C.

    2014-12-01

    Changing winds over the Southern Ocean have had dramatic impacts on Antarctic sea ice extent, anthropogenic heat and carbon uptake by the ocean, and the contribution of the Antarctic ice sheet to global sea level rise. An overall intensification of the surface westerly winds has been attributed to several different forcings, including stratospheric ozone depletion, greenhouse gasses, and tropical sea surface temperatures (SSTs). However, the relative roles of these drivers have not been well quantified. Reconciling previous explanations, here we show that a combination of tropical SSTs and stratospheric ozone loss largely explains the magnitude, regional patterns, and seasonality of observed lower tropospheric zonal wind trends over the Southern Ocean. We evaluate multiple ensembles of atmospheric model simulations, with each ensemble forced by one or a combination of drivers. Considering all months of the year, tropical SSTs are the largest contributor to observed zonal wind trends over 40°S-80°S. In austral summer, tropical SSTs and stratospheric ozone loss have contributed approximately equally to near-surface wind trends. The tropical contribution in austral summer is associated with tropics-wide warming, which has been moderated in recent decades by a prevalence of La-Niña events. The relative phasing of natural variability with anthropogenic forcing is therefore essential for understanding and predicting Southern Ocean climate change.

  9. Power Control for Direct-Driven Permanent Magnet Wind Generator System with Battery Storage

    Science.gov (United States)

    Guang, Chu Xiao; Ying, Kong

    2014-01-01

    The objective of this paper is to construct a wind generator system (WGS) loss model that addresses the loss of the wind turbine and the generator. It aims to optimize the maximum effective output power and turbine speed. Given that the wind generator system has inertia and is nonlinear, the dynamic model of the wind generator system takes the advantage of the duty of the Buck converter and employs feedback linearization to design the optimized turbine speed tracking controller and the load power controller. According to that, this paper proposes a dual-mode dynamic coordination strategy based on the auxiliary load to reduce the influence of mode conversion on the lifetime of the battery. Optimized speed and power rapid tracking as well as the reduction of redundant power during mode conversion have gone through the test based on a 5 kW wind generator system test platform. The generator output power as the capture target has also been proved to be efficient. PMID:25050405

  10. Power control for direct-driven permanent magnet wind generator system with battery storage.

    Science.gov (United States)

    Guang, Chu Xiao; Ying, Kong

    2014-01-01

    The objective of this paper is to construct a wind generator system (WGS) loss model that addresses the loss of the wind turbine and the generator. It aims to optimize the maximum effective output power and turbine speed. Given that the wind generator system has inertia and is nonlinear, the dynamic model of the wind generator system takes the advantage of the duty of the Buck converter and employs feedback linearization to design the optimized turbine speed tracking controller and the load power controller. According to that, this paper proposes a dual-mode dynamic coordination strategy based on the auxiliary load to reduce the influence of mode conversion on the lifetime of the battery. Optimized speed and power rapid tracking as well as the reduction of redundant power during mode conversion have gone through the test based on a 5 kW wind generator system test platform. The generator output power as the capture target has also been proved to be efficient.

  11. Wind-driven SEIG supplying DC microgrid through a single-stage power converter

    Directory of Open Access Journals (Sweden)

    Vellapatchi Nayanar

    2016-09-01

    Full Text Available Nowadays, there is an increased emphasis on utilizing the renewable energy sources and selection of suitable power converters for supplying dc microgrid. Among the various renewable energy sources, wind energy stands first in terms of installed capacity. So, an attempt is made in this paper for supplying dc microgrid utilizing wind energy. A self-excited induction generator has been used in the proposed wind energy conversion system (WECS. A single-stage power converter, namely, semi-converter is connected between the SEIG and dc grid terminals for closed-loop control of the proposed system. A perturb and observe (P&O based maximum power point tracking (MPPT algorithm has been developed and implemented using a dsPIC30F4011 digital controller. In this MPPT algorithm, the firing angle of the converter is adjusted by continuously monitoring the dc grid current for a given wind velocity. For analyzing the proposed system, a MATLAB/Simulink model has been developed by selecting the various components starting from wind-turbine model to the power converter supplying dc microgrid. Successful working of the proposed WECS has also been shown through experimental results obtained on a prototype model developed in the laboratory.

  12. Mechanical-magnetic-electric coupled behaviors for stress-driven Terfenol-D energy harvester

    Directory of Open Access Journals (Sweden)

    Shuying Cao

    2017-05-01

    Full Text Available The stress-driven Terfernol-D energy harvester exhibits the nonlinear mechanical-magnetic-electric coupled (MMEC behaviors and the eddy current effects. To analyze and design the device, it is necessary to establish an accurate model of the device. Based on the effective magnetic field expression, the constitutive equations with eddy currents and variable coefficients, and the dynamic equations, a nonlinear dynamic MMEC model for the device is founded. Comparisons between the measured and calculated results show that the model can describe the nonlinear coupled curves of magnetization versus stress and strain versus stress under different bias fields, and can provide the reasonable data trends of piezomagnetic coefficients, Young’s modulus and relative permeability for Terfenol-D. Moreover, the calculated power results show that the model can determine the optimal bias conditions, optimal resistance, suitable proof mass, suitable slices for the maximum energy extraction of the device under broad stress amplitude and broad frequency.

  13. Diffusion-driven proton exchange membrane fuel cell for converting fermenting biomass to electricity.

    Science.gov (United States)

    Malati, P; Mehrotra, P; Minoofar, P; Mackie, D M; Sumner, J J; Ganguli, R

    2015-10-01

    A membrane-integrated proton exchange membrane fuel cell that enables in situ fermentation of sugar to ethanol, diffusion-driven separation of ethanol, and its catalytic oxidation in a single continuous process is reported. The fuel cell consists of a fermentation chamber coupled to a direct ethanol fuel cell. The anode and fermentation chambers are separated by a reverse osmosis (RO) membrane. Ethanol generated from fermented biomass in the fermentation chamber diffuses through the RO membrane into a glucose solution contained in the DEFC anode chamber. The glucose solution is osmotically neutral to the biomass solution in the fermentation chamber preventing the anode chamber from drying out. The fuel cell sustains >1.3 mW cm(-2) at 47°C with high discharge capacity. No separate purification or dilution is necessary, resulting in an efficient and portable system for direct conversion of fermenting biomass to electricity. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Electrically driven quantum dot-micropillar single photon source with 34% overall efficiency

    Science.gov (United States)

    Heindel, T.; Schneider, C.; Lermer, M.; Kwon, S. H.; Braun, T.; Reitzenstein, S.; Höfling, S.; Kamp, M.; Forchel, A.

    2010-01-01

    We report on triggered single photon emission from low mode volume electrically driven quantum dot-micropillar cavities at repetition rates of up to 220 MHz. Due to an optimized layout of the doped planar microcavity and an advanced lateral current injection scheme, highly efficient single photon sources are realized. While g(2)(0)-values as low as 0.13±0.05 and a Purcell factor of 4 are observed for a 2.0 μm diameter micropillar, single photon emission at a rate of (35±7) MHz and an overall efficiency of (34±7)% are demonstrated for a 3.0 μm device.

  15. Constructing a Plastic Bottle Wind Turbine as a Practical Aid for Learning about Using Wind Energy to Generate Electricity

    Science.gov (United States)

    Appleyard, S. J.

    2009-01-01

    A simple horizontal axis wind turbine can be easily constructed using a 1.5 l PET plastic bottle, a compact disc and a small dynamo. The turbine operates effectively at low wind speeds and has a rotational speed of 500 rpm at a wind speed of about 14 km h[superscript -1]. The wind turbine can be used to demonstrate the relationship between open…

  16. Computational and Experimental Investigation for an Optimal Design of Industrial Windows to Allow Natural Ventilation during Wind-Driven Rain

    Directory of Open Access Journals (Sweden)

    Kritana Prueksakorn

    2015-08-01

    Full Text Available With an increased awareness of sustainability issues, natural ventilation has become an elegant method for reducing the costs and environmental effects of the energy that is used to maintain comfortable indoor air quality rather than using mechanical ventilation. The windows in many industrial buildings are continuously open to exhaust pollutants and intake fresh air. Though windows are functional and efficient for natural ventilation, rainwater is able to penetrate through the windows during wind-driven rain. For industries in which the moisture content affects the quality of the product, the intrusion of a large amount of rainwater through windows must be prevented without compromising the effective ventilation. The aim of this research is to determine an innovative design for windows to accomplish the optimum of high ventilation and low rain penetration. For this purpose, windows are variously innovated and tested in full-scale measurements, reduced-scale wind-tunnel measurements and computational fluid dynamics (CFD. An artificial rain and wind velocity to mimic the average of the maximum values in Korea are created. The maximum reduction in rain penetration of over 98% compared to basic 90° open windows is attained with only a 4%–9% decrement of ventilation efficiency in the two recommended designs.

  17. Single-sided Natural Ventilation Driven by a Combination of Wind Pressure and Temperature Difference

    DEFF Research Database (Denmark)

    Larsen, Tine Steen; Heiselberg, Per

    2007-01-01

    . In both situations the aim is to obtain a good indoor environment but to control the amount of air, some basic knowledge of the flow through an opening is necessary. The amount of air going through the window opening in single-sided ventilation will depend on the wind speed near the building......, which make the prediction difficult. From earlier work, a few design expressions for single-sided ventilation already exist, but none of these include the wind direction, which here is an important parameter. Therefore several wind tunnel experiments are made in this work to find a new design expression......Natural ventilation is a commonly used principle when ventilation systems for buildings are designed. The ventilation can either be obtained by automatically controlled openings in the building envelope, or it can just be the simple action of opening a door or a window to let the fresh air in...

  18. Reliability of offshore wind power production under extreme wind conditions. Deliverable D 9.5. Work Package 9: Electrical grid

    DEFF Research Database (Denmark)

    Cutululis, Nicolaos Antonio; Zeni, Lorenzo

    . The aspects investigated are storm events occurrences and durations, storm control strategy impact on the capacity factor (lost production), the loss of production (power produced from wind drops below a certain threshold due to high wind speeds and storm controller) and finally, the wind power production...

  19. Electric field driven destabilization of the insulating state in nominally pure LaMnO3.

    Science.gov (United States)

    Nath, Rajib; Raychaudhuri, A K; Mukovskii, Ya M; Mondal, Parthasarathi; Bhattacharya, Dipten; Mandal, P

    2013-04-17

    We report an electric field driven destabilization of the insulating state in nominally pure LaMnO3 single crystal with a moderate field which leads to a resistive state transition below 300 K. The transition is between the insulating state in LaMnO3 and a high resistance bad metallic state that has a temperature independent resistivity. The transition occurs at a threshold field (Eth) that shows a steep enhancement on cooling. While at lower temperatures the transition is sharp and involves a large change in resistance, it softens on heating and is eventually absent above 280 K. When the Mn(4+) content is increased by Sr substitution up to x = 0.1, the observed transition, although observable in a certain temperature range, softens considerably. This observation has been explained as a bias driven percolation type transition between two co-existing phases, where the majority phase is a charge and orbitally ordered polaronic insulating phase and the minority phase is a bad metallic phase. The mobile fraction f of the bad metallic phase deduced from the experimental data follows an activated kinetics as f = fo(E)exp(-Δ/kBT) with the activation energy Δ ≈ 200 meV, and the pre-factor fo(E) is a strong function of the field that leads to a rapid enhancement of f on application of field, leading to the resistive state transition. We suggest likely scenarios for such co-existing phases in nominally pure LaMnO3 that can lead to the bias driven percolation type transition.

  20. Temporal Code-Driven Stimulation: Definition and Application to Electric Fish Signaling

    Science.gov (United States)

    Lareo, Angel; Forlim, Caroline G.; Pinto, Reynaldo D.; Varona, Pablo; Rodriguez, Francisco de Borja

    2016-01-01

    Closed-loop activity-dependent stimulation is a powerful methodology to assess information processing in biological systems. In this context, the development of novel protocols, their implementation in bioinformatics toolboxes and their application to different description levels open up a wide range of possibilities in the study of biological systems. We developed a methodology for studying biological signals representing them as temporal sequences of binary events. A specific sequence of these events (code) is chosen to deliver a predefined stimulation in a closed-loop manner. The response to this code-driven stimulation can be used to characterize the system. This methodology was implemented in a real time toolbox and tested in the context of electric fish signaling. We show that while there are codes that evoke a response that cannot be distinguished from a control recording without stimulation, other codes evoke a characteristic distinct response. We also compare the code-driven response to open-loop stimulation. The discussed experiments validate the proposed methodology and the software toolbox. PMID:27766078

  1. Wrist Rehabilitation Assisted by an Electromyography-Driven Neuromuscular Electrical Stimulation Robot After Stroke.

    Science.gov (United States)

    Hu, Xiao-Ling; Tong, Raymond Kai-yu; Ho, Newmen S K; Xue, Jing-jing; Rong, Wei; Li, Leonard S W

    2015-09-01

    Augmented physical training with assistance from robot and neuromuscular electrical stimulation (NMES) may introduce intensive motor improvement in chronic stroke. To compare the rehabilitation effectiveness achieved by NMES robot-assisted wrist training and that by robot-assisted training. This study was a single-blinded randomized controlled trial with a 3-month follow-up. Twenty-six hemiplegic subjects with chronic stroke were randomly assigned to receive 20-session wrist training with an electromyography (EMG)-driven NMES robot (NMES robot group, n = 11) and with an EMG-driven robot (robot group, n = 15), completed within 7 consecutive weeks. Clinical scores, Fugl-Meyer Assessment (FMA), Modified Ashworth Score (MAS), and Action Research Arm Test (ARAT) were used to evaluate the training effects before and after the training, as well as 3 months later. An EMG parameter, muscle co-contraction index, was also applied to investigate the session-by-session variation in muscular coordination patterns during the training. The improvement in FMA (shoulder/elbow, wrist/hand) obtained in the NMES robot group was more significant than the robot group (P robot group (P robot group. NMES robot-assisted training showed better performance in releasing muscle co-contraction than the robot-assisted across the training sessions (P robot-assisted wrist training was more effective than the pure robot. The additional NMES application in the treatment could bring more improvements in the distal motor functions and faster rehabilitation progress. © The Author(s) 2014.

  2. Modeling and Simulation of a Wind Turbine Driven Induction Generator Using Bond Graph

    Directory of Open Access Journals (Sweden)

    Lachouri Abderrazak

    2015-12-01

    Full Text Available The objective of this paper is to investigate the modelling and simulation of wind turbine applied on induction generator with bond graph methodology as   a graphical and multi domain approach. They provide a precise and unambiguous modelling tool, which allows for the specification of hierarchical physical structures. The paper begins with an introduction to the bond graphs technique, followed by an implementation of the wind turbine model. Simulation results illustrate the simplified system response obtained using the 20-sim software.

  3. Study on the CO2 electric driven fixed swash plate type compressor for eco-friendly vehicles

    Science.gov (United States)

    Nam, Donglim; Kim, Kitae; Lee, Jehie; Kwon, Yunki; Lee, Geonho

    2017-08-01

    The purpose of this study is to experiment and to performance analysis about the electric-driven fixed swash plate compressor using alternate refrigerant(R744). Comprehensive simulation model for an electric driven compressor using CO2 for eco-friendly vehicle is presented. This model consists of compression model and dynamic model. The compression model included valve dynamics, leakage, and heat transfer models. And the dynamic model included frictional loss between piston ring and cylinder wall, frictional loss between shoe and swash plate, frictional loss of bearings, and electric efficiency. Especially, because the efficiency of an electric parts(motor and inverter) in the compressor affects the loss of the compressor, the dynamo test was performed. We made the designed compressor, and tested the performance of the compressor about the variety pressure conditions. Also we compared the performance analysis result and performance test result.

  4. Thermal and electrical properties of thermal-grease-insulated REBCO superconducting coils with respect to winding tension

    Science.gov (United States)

    Song, Jung-Bin; Choi, Yoon Hyuck; Yang, Dong Gyu; Kim, Young-Gyun; Kim, Seong-Gyeom; Choi, Yeon Suk; Lee, Haigun

    2017-09-01

    This study investigates the thermal and electrical characteristics of a silicon-based grease insulation (GI) GdBCO coil with respect to the winding tension through charge, sudden discharge, and over-current tests. Charge and sudden discharge test results demonstrate that the charging/discharging delay time increases as the winding tension increases; this is because the characteristic resistance of the coil decreases due to the reduced contact resistance. The over-current test results confirm that the thermal/electrical stabilities of the GI coil are considerably enhanced with an increased winding tension resulting from improved thermal contact and the decrease in the electrical contact resistance between the turn-to-turn layers of the coil. Thus, as the winding tension increases, the charging/discharging rates decrease whereas the thermal/electrical stabilities improve. Overall, selecting the appropriate winding tension for a GI coil is critical for achieving thermal/electrical stabilities, as well as ameliorating the charging/discharging delay phenomenon generally observed in a no-insulation coil.

  5. HORIZONTAL AXIS MARINE CURRENT TURBINE DESIGN FOR WIND-ELECTRIC HYBRID SAILING BOAT

    Directory of Open Access Journals (Sweden)

    Serkan Ekinci

    2017-01-01

    Full Text Available In recent decades, the number of theoretical studies and applications on electric power production from renewable sources such as wind, solar, sea and tidal flows, has been increasing rapidly. Marine Current Turbines (MCTs, among the power turbines, produce power from alternating flows and are a means of power production even at lower flow rates in oceans and seas. In this study, while maintaining functional requirements, an initial and detailed design (mechanic and hydrodynamic, of an MCT fixed on a sailing boat and at sail which extracts power from the flow around the boat, is undertaken. In the design stages, for analysis and optimization of the marine turbine blade design, the Momentum Blade Element Method is utilized. The Horizontal Axis Marine Turbine (HAMT, determined by the initial and mechanical design, is illustrated with its components included. Computational fluid dynamics (CFD analyses, covering turbine pod geometry at required flow rates and turbine speeds are performed. These analyses are performed very close to real conditions, considering sailing with and without the turbine running (on and off states. The alternator is determined from the results, and the final design which meets the design requirements, is obtained. As a result, a user friendly and innovative turbine design for sail boats, offering more power and efficiency, which is longer lasting compared to solar and wind technologies, that also makes use of renewable sources, such as wind and/or solar, and in addition stores and uses accumulated energy when needed, is proposed.

  6. The dynamics of wind-driven intraseasonal variability in the equatorial Indian Ocean

    Science.gov (United States)

    Nagura, M.; McPhaden, M. J.

    2012-12-01

    Variability in the equatorial Indian Ocean on intraseasonal time scales (defined as periods of 30-110 days) is investigated using satellite and in situ observations and a simple analytical linear long-wave equatorial beta-plane model. Despite the extreme simplicity of the model, which includes just the two gravest baroclinic mode Kelvin waves and first meridional mode Rossby waves, simulated surface zonal velocity and sea surface height compare very well with observations. Both observations and model are characterized by a red shift in the velocity spectrum relative to the wind forcing spectrum (Figure 1), which is attributable to a combination of factors, including (1) the near resonant excitation of Kelvin waves by eastward propagating winds, (2) constructive interference between wind-forced waves and Rossby waves reflected from the eastern boundary, and (3) the favored excitation of low-frequency waves whose zonal wavelengths are long compared to the zonal fetch of the wind. We decomposed variability in two broad period bands, namely, 30-70 days and 70-110 days, for detailed analysis. At periods of 30-70 days, zonal velocity tends to be stationary in the directly forced region along the equator owing to the competing contributions of Kelvin and Rossby waves. In contrast, at 70-110 day periods, zonal velocity propagates westward despite eastward propagation of zonal wind stress because of the combined influence of eastern boundary generated and wind-forced Rossby waves. Kelvin waves reflected from the western boundary are negligibly small, indicating that basin mode resonances are not prominent as has been previously suggested.igure 1: Variance preserving spectra at 0°, 80°E for (a) QSCAT zonal wind stress and (b) zonal velocity at 15 m depth from the analytic model (solid line), OSCAR (dotted line), and ADCP observations (dashed line). A triangle filter for three adjacent spectral estimates was applied 10 times to smooth the spectra. The dark shades represent

  7. Proliferation of metallic domains caused by inhomogeneous heating near the electrically-driven transition in VO$_2$ nanobeams

    OpenAIRE

    Singh, Sujay; Horrocks, Gregory; Marley, Peter M; Shi, Zhenzhong; Banerjee, Sarbajit; Sambandamurthy, G.

    2015-01-01

    We discuss the mechanisms behind the electrically driven insulator-metal transition in single crystalline VO$_2$ nanobeams. Our DC and AC transport measurements and the versatile harmonic analysis method employed show that non-uniform Joule heating causes phase inhomogeneities to develop within the nanobeam and is responsible for driving the transition in VO$_{2}$. A Poole-Frenkel like purely electric field induced transition is found to be absent and the role of percolation near and away fro...

  8. A molecular dynamics study of nanoconfined water flow driven by rotating electric fields under realistic experimental conditions

    DEFF Research Database (Denmark)

    De Luca, Sergio; Todd, Billy; Hansen, Jesper Schmidt

    2014-01-01

    In our recent work, J. Chem. Phys. 2013, 138, 154712, we demonstrated the feasibility of unidirectional pumping of water, exploiting translational–rotational momentum coupling using nonequilibrium molecular dynamics simulations. Flow can be sustained when the fluid is driven out of equilibrium...... nonequilibrium molecular dynamics and analytical solutions of the extended Navier–Stokes equations, including an external rotating electric field has been performed, showing excellent agreement when the electric field parameters match the aforementioned small energy dissipation region...

  9. A flexible platform for biofeedback-driven control and personalization of electrical nerve stimulation therapy.

    Science.gov (United States)

    Ward, Matthew P; Qing, Kurt Y; Otto, Kevin J; Worth, Robert M; John, Simon W M; Irazoqui, Pedro P

    2015-05-01

    Electrical vagus nerve stimulation is a treatment alternative for many epileptic and depressed patients whose symptoms are not well managed with pharmaceutical therapy. However, the fixed stimulus, open loop dosing mechanism limits its efficacy and precludes major advances in the quality of therapy. A real-time, responsive form of vagus nerve stimulation is needed to control nerve activation according to therapeutic need. This personalized approach to therapy will improve efficacy and reduce the number and severity of side effects. We present autonomous neural control, a responsive, biofeedback-driven approach that uses the degree of measured nerve activation to control stimulus delivery. We demonstrate autonomous neural control in rats, showing that it rapidly learns how to most efficiently activate any desired proportion of vagal A, B, and/or C fibers over time. This system will maximize efficacy by minimizing patient response variability and by minimizing therapeutic failures resulting from longitudinal decreases in nerve activation with increasing durations of treatment. The value of autonomous neural control equally applies to other applications of electrical nerve stimulation.

  10. Electrically and magnetically dual-driven Janus particles for handwriting-enabled electronic paper

    Energy Technology Data Exchange (ETDEWEB)

    Komazaki, Y., E-mail: komazaki@dt.k.u-tokyo.ac.jp; Hirama, H.; Torii, T. [Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba 277-8563 (Japan)

    2015-04-21

    In this work, we describe the synthesis of novel electrically and magnetically dual-driven Janus particles for a handwriting-enabled twisting ball display via the microfluidic technique. One hemisphere of the Janus particles contains a charge control agent, which allows the display color to be controlled by applying a voltage and superparamagnetic nanoparticles, allows handwriting by applying a magnetic field to the display. We fabricated a twisting ball display utilizing these Janus particles and tested the electric color control and handwriting using a magnet. As a result, the display was capable of permitting handwriting with a small magnet in addition to conventional color control using an applied voltage (80 V). Handwriting performance was improved by increasing the concentration of superparamagnetic nanoparticles and was determined to be possible even when 80 V was applied across the electrodes for 4 wt. % superparamagnetic nanoparticles in one hemisphere. This improvement was impossible when the concentration was reduced to 2 wt. % superparamagnetic nanoparticles. The technology presented in our work can be applied to low-cost, lightweight, highly visible, and energy-saving electronic message boards and large whiteboards because the large-size display can be fabricated easily due to its simple structure.

  11. Spin-valley dynamics of electrically driven ambipolar carbon-nanotube quantum dots

    Science.gov (United States)

    Osika, E. N.; Chacón, A.; Lewenstein, M.; Szafran, B.

    2017-07-01

    An ambipolar n-p double quantum dot defined by potential variation along a semiconducting carbon-nanotube is considered. We focus on the (1e,1h) charge configuration with a single excess electron of the conduction band confined in the n-type dot and a single missing electron in the valence band state of the p-type dot for which lifting of the Pauli blockade of the current was observed in the electric-dipole spin resonance (Laird et al 2013 Nat. Nanotechnol. 8 565). The dynamics of the system driven by periodic electric field is studied with the Floquet theory and the time-dependent configuration interaction method with the single-electron spin-valley-orbitals determined for atomistic tight-binding Hamiltonian. We find that the transitions lifting the Pauli blockade are strongly influenced by coupling to a vacuum state with an empty n dot and a fully filled p dot. The coupling shifts the transition energies and strongly modifies the effective g factors for axial magnetic field. The coupling is modulated by the bias between the dots but it appears effective for surprisingly large energy splitting between the (1e,1h) ground state and the vacuum (0e, 0h) state. Multiphoton transitions and high harmonic generation effects are also discussed.

  12. A Unified Directional Spectrum for Long and Short Wind-Driven Waves

    Science.gov (United States)

    Elfouhaily, T.; Chapron, B.; Katsaros, K.; Vandemark, D.

    1997-01-01

    Review of several recent ocean surface wave models finds that while comprehensive in many regards, these spectral models do not satisfy certain additional, but fundamental, criteria. We propose that these criteria include the ability to properly describe diverse fetch conditions and to provide agreement with in situ observations of Cox and Munk [1954] and Jiihne and Riemer [1990] and Hara et al. [1994] data in the high-wavenumber regime. Moreover, we find numerous analytically undesirable aspects such as discontinuities across wavenumber limits, nonphysical tuning or adjustment parameters, and noncentrosymmetric directional spreading functions. This paper describes a two-dimensional wavenumber spectrum valid over all wavenumbers and analytically amenable to usage in electromagnetic models. The two regime model is formulated based on the Joint North Sea Wave Project (JONSWAP) in the long-wave regime and on the work of Phillips [1985] and Kitaigorodskii [1973] at the high wavenumbers. The omnidirectional and wind-dependent spectrum is constructed to agree with past and recent observations including the criteria mentioned above. The key feature of this model is the similarity of description for the high- and low-wavenumber regimes; both forms are posed to stress that the air-sea interaction process of friction between wind and waves (i.e., generalized wave age, u/c) is occurring at all wavelengths simultaneously. This wave age parameterization is the unifying feature of the spectrum. The spectrum's directional spreading function is symmetric about the wind direction and has both wavenumber and wind speed dependence. A ratio method is described that enables comparison of this spreading function with previous noncentrosymmetric forms. Radar data are purposefully excluded from this spectral development. Finally, a test of the spectrum is made by deriving roughness length using the boundary layer model of Kitaigorodskii. Our inference of drag coefficient versus wind speed

  13. A New Approach for Modeling Darrieus-Type Vertical Axis Wind Turbine Rotors Using Electrical Equivalent Circuit Analogy: Basis of Theoretical Formulations and Model Development

    National Research Council Canada - National Science Library

    Pierre Tchakoua; Rene Wamkeue; Mohand Ouhrouche; Tommy Andy Tameghe; Gabriel Ekemb

    2015-01-01

    .... Thus, models can significantly reduce design, development and optimization costs. This paper proposes a novel equivalent electrical model for Darrieus-type vertical axis wind turbines (DTVAWTs...

  14. Electricity generation comparison of food waste-based bioenergy with wind and solar powers: A mini review

    Directory of Open Access Journals (Sweden)

    Ngoc Bao Dung Thi

    2016-09-01

    Full Text Available The food waste treatment-based anaerobic digestion has been proven to play a primary role in electricity industry with high potentially economic benefits, which could reduce electricity prices in comparison with other renewable energy resources such as wind and solar power. The levelized costs of electricity were reported to be 65, 190, 130 and 204 US$ MWh−1 for food waste treatment in anaerobic landfill, anaerobic digestion biogas, solar power, and wind power, respectively. As examples, the approaches of food waste treatment via anaerobic digestion to provide a partial energy supply for many countries in future were estimated as 42.9 TWh yr−1 in China (sharing 0.87% of total electricity generation, 7.04 TWh yr−1 in Japan (0.64% of total electricity generation and 13.3 TWh yr−1 in the US (0.31% of total electricity generation. Electricity generation by treating food waste is promised to play an important role in renewable energy management. Comparing with wind and solar powers, converting food waste to bioenergy provides the lowest investment costs (500 US$ kW−1 and low operation cost (0.1 US$ kWh−1. With some limits in geography and season of other renewable powers, using food waste for electricity generation is supposedly to be a suitable solution for balancing energy demand in many countries.

  15. Enhanced Control for a Direct-driven Permanent Synchronous Generator Wind-power Generation System with Flywheel Energy Storage Unit Under Unbalanced Grid Fault

    DEFF Research Database (Denmark)

    Yao, Jun; Zhou, Te; Hu, Weihao

    2015-01-01

    This article presents an enhanced control strategy for a direct-driven permanent synchronous generator based wind-power generation system with a flywheel energy storage unit. The behaviors of the direct-driven permanent magnet synchronous generator system with a flywheel energy storage unit under......, the proposed coordinated control strategy for the direct-driven permanent magnet synchronous generator system with a flywheel energy storage unit has been validated by the simulation results of a 1-MW direct-driven permanent magnet synchronous generator wind power generation system with a flywheel energy......, the DC-link voltage oscillations can be effectively suppressed during the unbalanced grid fault by controlling the flywheel energy storage unit. Furthermore, a proportional–integral-resonant controller is designed for the flywheel motor to eliminate the oscillations in the DC-link voltage. Finally...

  16. Quantification and Costing of Domestic Electricity Generation for Armidale, New South Wales, Australia Utilising Micro Wind Turbines

    OpenAIRE

    Maklad, Yasser

    2014-01-01

    In this study, a general overview of energy and renewable energy sources available in Australia was introduced, household’s electricity situation in Australia was presented, and focus wind energy was conducted. A theoretical methodology for quantification and costing of selected micro wind turbines was introduced. This methodology was applied to Armidale city, New South Wales (NSW), Australia as a case study. The methodology involved utilisation of spread sheet application and HOMER software....

  17. Renewable energy integration into the Australian National Electricity Market: Characterising the energy value of wind and solar generation

    OpenAIRE

    Nicholas Boerema; Merlinde Kay; Iain MacGill

    2010-01-01

    This paper examines how key characteristics of the underlying wind and solar resources may impact on their energy value within the Australian National Electricity Market(NEM). Analysis has been performed for wind generation using half hour NEM data for South Australia over the 2008-9 financial year. The potential integration of large scale solar generation has been modelled using direct normal solar radiant energy measurements from the Bureau of Meteorology for six sites across the NEM. For w...

  18. Wind power integration with heat pumps, heat storages, and electric vehicles - Energy systems analysis and modelling

    Energy Technology Data Exchange (ETDEWEB)

    Hedegaard, K.

    2013-09-15

    This PhD investigates to which extent heat pumps, heat storages, and electric vehicles can support the integration of wind power. Considering the gaps in existing research, the main focus is put on individual heat pumps in the residential sector (one-family houses) and the possibilities for flexible operation, using the heat storage options available. Several energy systems analyses are performed using the energy system models, Balmorel, developed at the former TSO, ElkraftSystem, and, EnergyPLAN, developed at Aalborg University. The Danish energy system towards 2030, with wind power penetrations of up to 60 %, is used as a case study in most of the analyses. Both models have been developed further, resulting in an improved representation of individual heat pumps and heat storages. An extensive model add-on for Balmorel renders it possible to optimise investment and operation of individual heat pumps and different types of heat storages, in integration with the energy system. Total costs of the energy system are minimised in the optimisation. The add-on incorporates thermal building dynamics and covers various different heat storage options: intelligent heat storage in the building structure for houses with radiator heating and floor heating, respectively, heat accumulation tanks on the space heating circuit, as well as hot water tanks. In EnergyPLAN, some of the heat storage options have been modelled in a technical optimisation that minimises fuel consumption of the energy system and utilises as much wind power as possible. The energy systems analyses reveal that in terms of supporting wind power integration, the installation of individual heat pumps is an important step, while adding heat storages to the heat pumps is less influential. When equipping the heat pumps with heat storages, only moderate system benefits can be gained. Hereof, the main system benefit is that the need for peak/reserve capacity investments can be reduced through peak load shaving; in

  19. Numerical modeling of electrical-mechanical-acoustical behavior of a lumped acoustic source driven by a piezoelectric stack actuator

    NARCIS (Netherlands)

    Tajdari, Farnaz; Berkhoff, Arthur P.; de Boer, Andries; Sas, P

    2016-01-01

    The present work describes the electrical, mechanical and acoustical behavior of a thin honey-comb structure as an acoustic source. The acoustic source has to operate in the low frequency, quasi-static regime and is driven by a piezoelectric stack actuator. In addition, a two-way energy flow between

  20. Congestion-Driven Transmission Expansion Planning Considering Wind Power Generation in Spot Markets

    OpenAIRE

    Hamdi, Mohammd

    2017-01-01

    The integration of a massive number of large-scale wind turbines brought about urgent technical challenge to power transmission network operators in terms of secure power supply and energy dispatching optimization. In this paper, an optimal framework is proposed for transmission expansion planning in a deregulated power market environment. The level of congestion in the network is utilized as the driving signal for the need of network expansion. A compromise between the congestion cost and th...