WorldWideScience

Sample records for wind wave generation

  1. Phase spectral composition of wind generated ocean surface waves

    Digital Repository Service at National Institute of Oceanography (India)

    Varkey, M.J.

    A study of the composition of the phase spectra of wind generated ocean surface waves is carried out using wave records collected employing a ship borne wave recorder. It is found that the raw phase spectral estimates could be fitted by the Uniform...

  2. Energy dissipation through wind-generated breaking waves

    Institute of Scientific and Technical Information of China (English)

    ZHANG Shuwen; CAO Ruixue; XIE Lingling

    2012-01-01

    Wave breaking is an important process that controls turbulence properties and fluxes of heat and mass in the upper oceanic layer.A model is described for energy dissipation per unit area at the ocean surface attributed to wind-generated breaking waves,in terms of ratio of energy dissipation to energy input,windgenerated wave spectrum,and wave growth rate.Also advanced is a vertical distribution model of turbulent kinetic energy,based on an exponential distribution method.The result shows that energy dissipation rate depends heavily on wind speed and sea state.Our results agree well with predictions of previous works.

  3. Characteristics of Wind Generated Waves in the Delaware Estuary

    Science.gov (United States)

    Chen, J. L.; Ralston, D. K.; Geyer, W. R.; Chant, R. J.; Sommerfield, C. K.

    2016-02-01

    Coastal marshes provide important services for human uses such as fishery industry, recreation, ports and marine operations. Bombay Hook Wildlife Refuge, located along the western shore of the Delaware Estuary, has experienced substantial loss of salt marsh in recent decades. To evaluate the importance of different mechanisms which cause observed shoreline retreat, wave gauges were deployed along the dredged navigation channel and shoreline in the Delaware Estuary. A coupled wave and circulation modeling system (SWAN/ROMS) based on the most recent bathymetry (last updated 2013) is validated with waves observed during both calm and energetic conditions in November 2015. Simulation results based on different model parameterizations of whitecapping, bottom friction and the wind input source are compared. The tendency of observed wave steepness is more similar to a revised whitecapping source term [Westhuysen, 2007] than the default in SWAN model. Both model results and field data show that the generation/dissipation of waves in the Delaware estuary is determined by the local wind speed and channel depth. Whitecapping-induced energy dissipation is dominant in the channel, while dissipation due to bottom friction and depth-induced breaking become important on lateral shoals. To characterize the effects of wind fetch on waves in estuaries more generally, simulations with an idealized domain and varying wind conditions are compared and the results are expressed in terms of non-dimensional parameters. The simulations based on a 10m-depth uniform idealized channel show that the dissipation of waves is mainly controlled by whitecapping in all wind conditions. Under strong wind conditions (wind speed >10m/s) the effect of bottom friction becomes important so the simulated wave heights are no longer linearly correlated with wind speed.

  4. What a Sudden Downpour Reveals About Wind Wave Generation

    KAUST Repository

    Cavaleri, Luigi

    2018-04-12

    We use our previous numerical and measuring experience and the evidence from a rather unique episode at sea to summarise our doubts on the present physical approach in wave modelling. The evidence strongly suggests that generation by wind and dissipation by white-capping have a different physics than presently considered. Most of all they should be viewed as part of a single physical process.

  5. What a Sudden Downpour Reveals About Wind Wave Generation

    KAUST Repository

    Cavaleri, Luigi; Baldock, Tom; Bertotti, Luciana; Langodan, Sabique; Olfateh, Mohammad; Pezzutto, Paolo

    2018-01-01

    We use our previous numerical and measuring experience and the evidence from a rather unique episode at sea to summarise our doubts on the present physical approach in wave modelling. The evidence strongly suggests that generation by wind and dissipation by white-capping have a different physics than presently considered. Most of all they should be viewed as part of a single physical process.

  6. SOLAR WIND STRAHL BROADENING BY SELF-GENERATED PLASMA WAVES

    Energy Technology Data Exchange (ETDEWEB)

    Pavan, J.; Gaelzer, R. [UFPEL, Pelotas (Brazil); Vinas, A. F. [NASA GSFC, Greenbelt, MD 20771 (United States); Yoon, P. H. [IPST, UMD, College Park, MD (United States); Ziebell, L. F., E-mail: joel.pavan@ufpel.edu.br, E-mail: rudi@ufpel.edu.br, E-mail: adolfo.vinas@nasa.gov, E-mail: yoonp@umd.edu, E-mail: luiz.ziebell@ufrgs.br [UFRGS, Porto Alegre (Brazil)

    2013-06-01

    This Letter reports on the results of numerical simulations which may provide a possible explanation for the strahl broadening during quiet solar conditions. The relevant processes involved in the broadening are due to kinetic quasi-linear wave-particle interaction. Making use of static analytical electron distribution in an inhomogeneous field, it is found that self-generated electrostatic waves at the plasma frequency, i.e., Langmuir waves, are capable of scattering the strahl component, resulting in energy and pitch-angle diffusion that broadens its velocity distribution significantly. The present theoretical results provide an alternative or complementary explanation to the usual whistler diffusion scenario, suggesting that self-induced electrostatic waves at the plasma frequency might play a key role in broadening the solar wind strahl during quiet solar conditions.

  7. Early stages of wind wave and drift current generation under non-stationary wind conditions.

    Science.gov (United States)

    Robles-Diaz, Lucia; Ocampo-Torres, Francisco J.; Branger, Hubert

    2016-04-01

    Generation and amplification mechanisms of ocean waves are well understood under constant wind speed or limited fetch conditions. Under these situations, the momentum and energy transfers from air to water are also quite well known. However during the wind field evolution over the ocean, we may observe sometime high wind acceleration/deceleration situations (e.g. Mexican Tehuano or Mediterranean Mistral wind systems). The evolution of wave systems under these conditions is not well understood. The purpose of these laboratory experiments is to better understand the early stages of water-waves and surface-drift currents under non-stationary wind conditions and to determine the balance between transfers creating waves and surface currents during non-equilibrium situations. The experiments were conducted in the Institut Pythéas wind-wave facility in Marseille-France. The wave tank is 40 m long, 2.7 m wide and 1 m deep. The air section is 50 m long, 3 m wide and 1.8 m height. We used 11 different resistive wave-gauges located along the tank. The momentum fluxes in the air column were estimated from single and X hot-film anemometer measurements. The sampling frequency for wind velocity and surface displacement measurements was 256 Hz. Water-current measurements were performed with a profiling velocimeter. This device measures the first 3.5 cm of the water column with a frequency rate of 100Hz. During the experiments, the wind intensity was abruptly modified with a constant acceleration and deceleration over time. We observed that wind drag coefficient values for accelerated wind periods are lower than the ones reported in previous studies for constant wind speed (Large and Pond 1981; Ocampo-Torres et al. 2010; Smith 1980; Yelland and Taylor 1996). This is probably because the turbulent boundary layer is not completely developed during the increasing-wind sequence. As it was reported in some theoretical studies (Miles 1957; Phillips 1957; Kahma and Donelan 1988), we

  8. Bubbles generated from wind-steepened breaking waves: 2. Bubble plumes, bubbles, and wave characteristics

    NARCIS (Netherlands)

    Leifer, I.; Caulliez, G.; Leeuw, G.de

    2006-01-01

    Measurements of breaking-wave-generated bubble plumes were made in fresh (but not clean) water in a large wind-wave tunnel. To preserve diversity, a classification scheme was developed on the basis of plume dimensions and "optical density," or the plume's ability to obscure the background. Optically

  9. Numerical modeling of wind waves in the Black Sea generated by atmospheric cyclones

    Science.gov (United States)

    Fomin, V. V.

    2017-09-01

    The influence of the translation speed and intensity of atmospheric cyclones on surface wind waves in the Black Sea is investigated by using tightly-coupled model SWAN+ADCIRC. It is shown that the wave field has a spatial asymmetry, which depends on the velocity and intensity of the cyclone. The region of maximum waves is formed to the right of the direction of the cyclone motion. Speedier cyclones generate wind waves of lower height. The largest waves are generated at cyclonic translation speed of 7-9 m/s. This effect is due to the coincidence of the characteristic values of the group velocity of the dominant wind waves in the deep-water part of the Black Sea with the cyclone translation speed.

  10. Interpretation of nonlinearity in wind generated ocean surface waves

    Digital Repository Service at National Institute of Oceanography (India)

    Varkey, M.J.

    of sinusoidal component waves; a consequent idea arising out of Fourier analysis. It is hypothesised that a sea state which is always nonlinear to various degrees is a result of interaction, both linear and nonlinear, between nonlinear component waves...

  11. Secondary current properties generated by wind-induced water waves in experimental conditions

    Directory of Open Access Journals (Sweden)

    Michio Sanjou

    2014-06-01

    Full Text Available Secondary currents such as the Langmuir circulation are of high interest in natural rivers and the ocean because they have striking impacts on scour, sedimentation, and mass transport. Basic characteristics have been well-studied in straight open-channel flows. However, little is known regarding secondary circulation induced by wind waves. The presented study describes the generation properties of wind waves observed in the laboratory tank. Wind-induced water waves are known to produce large scale circulations. The phenomenon is observed together with high-speed and low-speed streaks, convergence and divergence zones, respectively. Therefore, it is important to determine the hydrodynamic properties of secondary currents for wind-induced water waves within rivers and lakes. In this study, using two high-speed CMOS cameras, stereoscopic particle image velocimetry (PIV measurements were conducted in order to reveal the distribution of all three components of velocity vectors. The experiments allowed us to investigate the three-dimensional turbulent structure under water waves and the generation mechanism of large-scale circulations. Additionally, a third CMOS camera was used to measure the spanwise profile of thefree-surface elevation. The time-series of velocity components and the free-surface were obtained simultaneously. From our experiments, free-surface variations were found to influence the instantaneous velocity distributions of the cross-sectional plane. We also considered thegeneration process by the phase analysis related to gravity waves and compared the contribution of the apparent stress.

  12. Simulation of an Underwater Acoustic Communication Channel Characterized by Wind-Generated Surface Waves and Bubbles

    NARCIS (Netherlands)

    Dol, H.S.; Colin, M.E.G.D.; Ainslie, M.A.; Walree, P.A. van; Janmaat, J.

    2012-01-01

    Sea surface scattering by wind-generated waves and bubbles is regarded to be the main non-platform related cause of the time variability of shallow acoustic communication channels. Simulations for predicting the quality of acoustic communication links in such channels thus require adequate modeling

  13. Wind Generators

    Science.gov (United States)

    1989-01-01

    When Enerpro, Inc. president, Frank J. Bourbeau, attempted to file a patent on a system for synchronizing a wind generator to the electric utility grid, he discovered Marshall Space Flight Center's Frank Nola's power factor controller. Bourbeau advanced the technology and received a NASA license and a patent for his Auto Synchronous Controller (ASC). The ASC reduces generator "inrush current," which occurs when large generators are abruptly brought on line. It controls voltage so the generator is smoothly connected to the utility grid when it reaches its synchronous speed, protecting the components from inrush current damage. Generator efficiency is also increased in light winds by applying lower than rated voltage. Wind energy is utilized to drive turbines to generate electricity for utility companies.

  14. A Proton-Cyclotron Wave Storm Generated by Unstable Proton Distribution Functions in the Solar Wind

    Science.gov (United States)

    Wicks, R. T.; Alexander, R. L.; Stevens, M.; Wilson, L. B., III; Moya, P. S.; Vinas, A.; Jian, L. K.; Roberts, D. A.; O’Modhrain, S.; Gilbert, J. A.; hide

    2016-01-01

    We use audification of 0.092 seconds cadence magnetometer data from the Wind spacecraft to identify waves with amplitudes greater than 0.1 nanoteslas near the ion gyrofrequency (approximately 0.1 hertz) with duration longer than 1 hour during 2008. We present one of the most common types of event for a case study and find it to be a proton-cyclotron wave storm, coinciding with highly radial magnetic field and a suprathermal proton beam close in density to the core distribution itself. Using linear Vlasov analysis, we conclude that the long-duration, large-amplitude waves are generated by the instability of the proton distribution function. The origin of the beam is unknown, but the radial field period is found in the trailing edge of a fast solar wind stream and resembles other events thought to be caused by magnetic field footpoint motion or interchange reconnection between coronal holes and closed field lines in the corona.

  15. An experimental study of the surface elevation probability distribution and statistics of wind-generated waves

    Science.gov (United States)

    Huang, N. E.; Long, S. R.

    1980-01-01

    Laboratory experiments were performed to measure the surface elevation probability density function and associated statistical properties for a wind-generated wave field. The laboratory data along with some limited field data were compared. The statistical properties of the surface elevation were processed for comparison with the results derived from the Longuet-Higgins (1963) theory. It is found that, even for the highly non-Gaussian cases, the distribution function proposed by Longuet-Higgins still gives good approximations.

  16. Bubbles generated from wind-steepened breaking waves: 1. Bubble plume bubbles

    NARCIS (Netherlands)

    Leifer, I.; Leeuw, G. de

    2006-01-01

    Measurements of bubble plumes from paddle-amplified, wind stress breaking waves were made in a large wind-wave channel during the LUMINY experiment in fresh (but not clean) water. Bubble plumes exhibited considerable variability with respect to dynamics, bubble size distribution, and physical

  17. Reserve Requirement Impacts of Microgrid Integration of Wind, Solar, and Ocean Wave Power Generation

    OpenAIRE

    Ortego Trujillo, Patxi

    2016-01-01

    The ocean wave energy is a free and abundant resource which has led to exploring new methods to take advantage of the energy in an efficient and profitable way. The wave energy harnessing techniques are not as mature as other renewable energy resources ones such as wind or solar. Nevertheless, in recent years wave energy converters (WECs) have been gaining attention and restoring confidence worldwide in their role to meet the increasing demands and strict environmental standards Ocean wave po...

  18. Role of Wind Filtering and Unbalanced Flow Generation in Middle Atmosphere Gravity Wave Activity at Chatanika Alaska

    Directory of Open Access Journals (Sweden)

    Colin C. Triplett

    2017-01-01

    Full Text Available The meteorological control of gravity wave activity through filtering by winds and generation by spontaneous adjustment of unbalanced flows is investigated. This investigation is based on a new analysis of Rayleigh LiDAR measurements of gravity wave activity in the upper stratosphere-lower mesosphere (USLM,40–50kmon 152 nights at Poker Flat Research Range (PFRR, Chatanika, Alaska (65◦ N, 147◦ W, over 13 years between 1998 and 2014. The LiDAR measurements resolve inertia-gravity waves with observed periods between 1 h and 4 h and vertical wavelengths between 2 km and 10 km. The meteorological conditions are defined by reanalysis data from the Modern-Era Retrospective Analysis for Research and Applications (MERRA. The gravity wave activity shows large night-to-night variability, but a clear annual cycle with a maximum in winter,and systematic interannual variability associated with stratospheric sudden warming events. The USLM gravity wave activity is correlated with the MERRA winds and is controlled by the winds in the lower stratosphere through filtering by critical layer filtering. The USLM gravity wave activity is also correlated with MERRA unbalanced flow as characterized by the residual of the nonlinear balance equation. This correlation with unbalanced flow only appears when the wind conditions are taken into account, indicating that wind filtering is the primary control of the gravity wave activity.

  19. Langmuir wave-packet generation from an electron beam propagating in the inhomogeneous solar wind

    International Nuclear Information System (INIS)

    Zaslavsky, A.; Maksimovic, M.; Volokitin, A. S.; Krasnoselskikh, V. V.; Bale, S. D.

    2010-01-01

    Recent in-situ observations by the TDS instrument equipping the STEREO spacecraft revealed that large amplitude spatially localized Langmuir waves are frequent in the solar wind, and correlated with the presence of suprathermal electron beams during type III events or close to the electron foreshock. We briefly present the new theoretical model used to perform the study of these localized electrostatic waves, and show first results of simulations of the destabilization of Langmuir waves by a beam propagating in the inhomogeneous solar wind. The main results are that the destabilized waves are mainly focalized near the minima of the density profiles, and that the nonlinear interaction of the waves with the resonant particles enhances this focalization compared to a situation in which the only propagation effects are taken into account.

  20. Reminiscences on the study of wind waves

    Science.gov (United States)

    MITSUYASU, Hisashi

    2015-01-01

    The wind blowing over sea surface generates tiny wind waves. They develop with time and space absorbing wind energy, and become huge wind waves usually referred to ocean surface waves. The wind waves cause not only serious sea disasters but also take important roles in the local and global climate changes by affecting the fluxes of momentum, heat and gases (e.g. CO2) through the air-sea boundary. The present paper reviews the selected studies on wind waves conducted by our group in the Research Institute for Applied Mechanics (RIAM), Kyushu University. The themes discussed are interactions between water waves and winds, the energy spectrum of wind waves, nonlinear properties of wind waves, and the effects of surfactant on some air-sea interaction phenomena. PMID:25864467

  1. Nonlinear generation of kinetic-scale waves by magnetohydrodynamic Alfvén waves and nonlocal spectral transport in the solar wind

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, J. S.; Wu, D. J. [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing (China); Voitenko, Y.; De Keyser, J., E-mail: js_zhao@pmo.ac.cn [Solar-Terrestrial Centre of Excellence, Space Physics Division, Belgian Institute for Space Aeronomy, Ringlaan-3-Avenue Circulaire, B-1180 Brussels (Belgium)

    2014-04-20

    We study the nonlocal nonlinear coupling and generation of kinetic Alfvén waves (KAWs) and kinetic slow waves (KSWs) by magnetohydrodynamic Alfvén waves (MHD AWs) in conditions typical for the solar wind in the inner heliosphere. This cross-scale process provides an alternative to the turbulent energy cascade passing through many intermediate scales. The nonlinearities we study are proportional to the scalar products of wave vectors and hence are called 'scalar' ones. Despite the strong Landau damping of kinetic waves, we found fast growing KAWs and KSWs at perpendicular wavelengths close to the ion gyroradius. Using the parametric decay formalism, we investigate two independent decay channels for the pump AW: forward decay (involving co-propagating product waves) and backward decay (involving counter-propagating product waves). The growth rate of the forward decay is typically 0.05 but can exceed 0.1 of the pump wave frequency. The resulting spectral transport is nonlocal and anisotropic, sharply increasing perpendicular wavenumbers but not parallel ones. AWs and KAWs propagating against the pump AW grow with about the same rate and contribute to the sunward wave flux in the solar wind. Our results suggest that the nonlocal decay of MHD AWs into KAWs and KSWs is a robust mechanism for the cross-scale spectral transport of the wave energy from MHD to dissipative kinetic scales in the solar wind and similar media.

  2. Abnormal storm waves in the winter East/Japan Sea: generation process and hindcasting using an atmosphere-wind wave modelling system

    Directory of Open Access Journals (Sweden)

    H. S. Lee

    2010-04-01

    Full Text Available Abnormal storm waves cause coastal disasters along the coasts of Korean Peninsula and Japan in the East/Japan Sea (EJS in winter, arising due to developed low pressures during the East Asia winter monsoon. The generation of these abnormal storm waves during rough sea states were studied and hindcast using an atmosphere-wave coupled modelling system. Wind waves and swell due to developed low pressures were found to be the main components of abnormal storm waves. The meteorological conditions that generate these waves are classified into three patterns based on past literature that describes historical events as well as on numerical modelling. In hindcasting the abnormal storm waves, a bogussing scheme originally designed to simulate a tropical storm in a mesoscale meteorological model was introduced into the modelling system to enhance the resolution of developed low pressures. The modelling results with a bogussing scheme showed improvements in terms of resolved low pressure, surface wind field, and wave characteristics obtained with the wind field as an input.

  3. Comparison Study on Wind Input and Whitecapping Dissipation Expressions in Numerical Simulation of Typhoon Generated Waves

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In order to investigate the effect of wind input and whitecapping dissipation on the simulation of typhoon-waves, three experiments are conducted with the latest version of SWAN (Simulating Waves Nearshore) model. The three experiments adopt the Komen, Janssens, and Westhuysen expressions for wind input and whitecapping dissipation, respectively. Besides the above-mentioned source terms, other parameterization schemes in these experiments are the same. It shows that the experiment with the Westhuysen expression result in the least simulation errors while that with the Janssens expression has the most. The results from the experiments with Komen and Westhuysen expressions show that the differences in significant wave height (SWH) have a good correlation with the differences in dissipation energy caused by whitecapping. This indicates that the whitecapping dissipation source term plays an important role in the resultant differences of the simulated SWH between the two experiments.

  4. Probability function of breaking-limited surface elevation. [wind generated waves of ocean

    Science.gov (United States)

    Tung, C. C.; Huang, N. E.; Yuan, Y.; Long, S. R.

    1989-01-01

    The effect of wave breaking on the probability function of surface elevation is examined. The surface elevation limited by wave breaking zeta sub b(t) is first related to the original wave elevation zeta(t) and its second derivative. An approximate, second-order, nonlinear, non-Gaussian model for zeta(t) of arbitrary but moderate bandwidth is presented, and an expression for the probability density function zeta sub b(t) is derived. The results show clearly that the effect of wave breaking on the probability density function of surface elevation is to introduce a secondary hump on the positive side of the probability density function, a phenomenon also observed in wind wave tank experiments.

  5. A Review of Parametric Descriptions of Tropical Cyclone Wind-Wave Generation

    Directory of Open Access Journals (Sweden)

    Ian R. Young

    2017-10-01

    Full Text Available More than three decades of observations of tropical cyclone wind and wave fields have resulted in a detailed understanding of wave-growth dynamics, although details of the physics are still lacking. These observations are presented in a consistent manner, which provides the basis to be able to characterize the full wave spectrum in a parametric form throughout tropical cyclones. The data clearly shows that an extended fetch model can be used to represent the maximum significant wave height in such storms. The shape stabilizing influence of nonlinear interactions means that the spectral shape is remarkably similar to fetch-limited cases. As such, the tropical cyclone spectrum can also be described by using well-known parametric models. A detailed process is described to parameterize the wave spectrum at any point in a tropical cyclone.

  6. Turbulent wind waves on a water current

    Directory of Open Access Journals (Sweden)

    M. V. Zavolgensky

    2008-05-01

    Full Text Available An analytical model of water waves generated by the wind over the water surface is presented. A simple modeling method of wind waves is described based on waves lengths diagram, azimuthal hodograph of waves velocities and others. Properties of the generated waves are described. The wave length and wave velocity are obtained as functions on azimuth of wave propagation and growth rate. Motionless waves dynamically trapped into the general picture of three dimensional waves are described. The gravitation force does not enter the three dimensional of turbulent wind waves. That is why these waves have turbulent and not gravitational nature. The Langmuir stripes are naturally modeled and existence of the rogue waves is theoretically proved.

  7. Development of an Active Power Reserve Management Method for DC Applied Wave-Wind Combined Generation Systems

    Directory of Open Access Journals (Sweden)

    Seungmin Jung

    2015-11-01

    Full Text Available A system that combines a wind turbine and a wave generator can share the off-shore platform and therefore mix the advantages of the transmission system construction and the power conversion system. The current hybrid generation system considers output limitation according to the instructions of the transmission system operator (TSO, and controls the profile using wind turbine pitch control. However, the integrated wave generation system utilizing a DC network does not adapt a power limitation scheme due to its mechanical constraints. In this paper, a control plan focusing on the electrical section of wave generators is formed in order to effectively manage the output profile of the hybrid generation system. The plan pays attention to power reserve flexibility for the utility grid using the analysis of the controllable elements. Comparison with the existing system is performed based on real offshore conditions. With the help of power system computer aided design (PSCAD simulation, the ability of the novel technique is estimated by proposing the real power control based on the reference signal of TSO and the reactive power capacity it produces.

  8. First simultaneous measurements of waves generated at the bow shock in the solar wind, the magnetosphere and on the ground

    Science.gov (United States)

    Clausen, L. B. N.; Yeoman, T. K.; Fear, R. C.; Behlke, R.; Lucek, E. A.; Engebretson, M. J.

    2009-01-01

    On 5 September 2002 the Geotail satellite observed the cone angle of the Interplanetary Magnetic Field (IMF) change to values below 30° during a 56 min interval between 18:14 and 19:10 UT. This triggered the generation of upstream waves at the bow shock, 13 RE downstream of the position of Geotail. Upstream generated waves were subsequently observed by Geotail between 18:30 and 18:48 UT, during times the IMF cone angle dropped below values of 10°. At 18:24 UT all four Cluster satellites simultaneously observed a sudden increase in wave power in all three magnetic field components, independent of their position in the dayside magnetosphere. We show that the 10 min delay between the change in IMF direction as observed by Geotail and the increase in wave power observed by Cluster is consistent with the propagation of the IMF change from the Geotail position to the bow shock and the propagation of the generated waves through the bow shock, magnetosheath and magnetosphere towards the position of the Cluster satellites. We go on to show that the wave power recorded by the Cluster satellites in the component containing the poloidal and compressional pulsations was broadband and unstructured; the power in the component containing toroidal oscillations was structured and shows the existence of multi-harmonic Alfvénic continuum waves on field lines. Model predictions of these frequencies fit well with the observations. An increase in wave power associated with the change in IMF direction was also registered by ground based magnetometers which were magnetically conjunct with the Cluster satellites during the event. To the best of our knowledge we present the first simultaneous observations of waves created by backstreaming ions at the bow shock in the solar wind, the dayside magnetosphere and on the ground.

  9. Considerations and Optimization of Time-Resolved PIV Measurements near Complex Wind-Generated Air-Water Wave Interface

    Science.gov (United States)

    Stegmeir, Matthew; Markfort, Corey

    2017-11-01

    Time Resolved PIV measurements are applied on both sides of air-water interface in order to study the coupling between air and fluid motion. The multi-scale and 3-dimensional nature of the wave structure poses several unique considerations to generate optimal-quality data very near the fluid interface. High resolution and dynamic range in space and time are required to resolve relevant flow scales along a complex and ever-changing interface. Characterizing the two-way coupling across the air-water interface provide unique challenges for optical measurement techniques. Approaches to obtain near-boundary measurement on both sides of interface are discussed, including optimal flow seeding procedures, illumination, data analysis, and interface tracking. Techniques are applied to the IIHR Boundary-Layer Wind-Wave Tunnel and example results presented for both sides of the interface. The facility combines a 30m long recirculating water channel with an open-return boundary layer wind tunnel, allowing for the study of boundary layer turbulence interacting with a wind-driven wave field.

  10. Northeast storms ranked by wind stress and wave-generated bottom stress observed in Massachusetts Bay, 1990-2006

    Science.gov (United States)

    Butman, B.; Sherwood, C.R.; Dalyander, P.S.

    2008-01-01

    Along the coast of the northeastern United States, strong winds blowing from the northeast are often associated with storms called northeasters, coastal storms that strongly influence weather. In addition to effects caused by wind stress, the sea floor is affected by bottom stress associated with these storms. Bottom stress caused by orbital velocities associated with surface waves integrated over the duration of a storm is a metric of storm strength at the sea floor. Near-bottom wave-orbital velocities calculated by using measurements of significant wave height and dominant wave period and the parametric spectral method described in Wiberg and Sherwood [Wiberg, P.L., Sherwood, C.R. Calculating wave-generated bottom orbital velocities from surface wave parameters. Computers in Geosciences, in press] compared well with observations in Massachusetts Bay. Integrated bottom-wave stress (called IWAVES), calculated at 30 m water depth, and a companion storm-strength metric, integrated surface wind stress at 10 m (called IWINDS), are used to provide an overview of the strength, frequency, and timing of large storms in Massachusetts Bay over a 17-year period from January 1990 through December 2006. These new metrics reflect both storm duration and intensity. Northeast storms were the major cause of large waves in Massachusetts Bay because of the long fetch to the east: of the strongest 10% of storms (n=38) ranked by IWAVES, 22 had vector-averaged wind stress from the northeast quadrant. The Blizzard of December 1992, the Perfect Storm of October 1991, and a December 2003 storm were the strongest three storms ranked by IWAVES and IWINDS, and all were northeasters. IWAVES integrated over the winter season (defined as October-May) ranged by about a factor of 11; the winters with the highest integrated IWAVES were 1992-1993 and 2004-2005 and the winter with the lowest integrated IWAVES was 2001-2002. May 2005 was the only month in the 17-year record that two of the nine

  11. Effect of climate change on wind waves generated by anticyclonic cold front intrusions in the Gulf of Mexico

    Science.gov (United States)

    Appendini, Christian M.; Hernández-Lasheras, Jaime; Meza-Padilla, Rafael; Kurczyn, Jorge A.

    2018-01-01

    Anticyclonic cold surges entering the Gulf of Mexico (Nortes) generate ocean waves that disrupt maritime activities. Norte derived waves are less energetic than the devastating waves from tropical cyclones, but more frequent ( 22 events/year) and with larger spatial influence. Despite their importance, few studies characterize Nortes derived waves and assess the effects of climate change on their occurrence. This study presents a method to identify and characterize Nortes with relation to their derived waves in the Gulf of Mexico. We based the identification of Nortes on synoptic measurements of pressure differences between Yucatan and Texas and wind speed at different buoy locations in the Gulf of Mexico. Subsequently, we identified the events in the CFSR reanalysis (present climate) and the CNRM-M5 model for the present climate and the RCP 8.5 scenario. We then forced a wave model to characterize the wave power generated by each event, followed by a principal component analysis and classification by k-means clustering analysis. Five different Nortes types were identified, each one representing a characteristic intensity and area of influence of the Norte driven waves. Finally, we estimated the occurrence of each Norte type for the present and future climates, where the CNRM-M5 results indicate that the high-intensity events will be less frequent in a warming climate, while mild events will become more frequent. The consequences of such changes may provide relief for maritime and coastal operations because of reduced downtimes. This result is particularly relevant for the operational design of coastal and marine facilities.

  12. Strong winds and waves offshore

    DEFF Research Database (Denmark)

    Larsén, Xiaoli Guo

    2016-01-01

    is on the meteorologi al and o eani onditions related to storm winds and waves over the North Sea. With regard to the o shore wind energy appli ation, the parameters addressed here in lude: extreme wind and extreme waves, storm wind and waves and turbulen e issues for o shore onditions.......This report is prepared for Statoil, with the intention to introdu e DTU Wind Energy's ongoing resear h a tivities on o shore extreme wind and wave onditions. The purpose is to share our re ent ndings and to establish possible further ollaboration with Statoil. The fo us of this report...

  13. 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.

  14. Wind electric power generation

    International Nuclear Information System (INIS)

    Koch, M.K.; Wind, L.; Canter, B.; Moeller, T.

    2001-01-01

    The monthly statistics of wind electric power generation in Denmark are compiled from information given by the owners of the private wind turbines. For each wind turbine the name of the site and of the type of turbine is given, and the power generation data are given for the month in question together with the total production in 1999 and 2000. Also the data of operation start are given. On the map of Denmark the sites of the wind turbines are marked. (CLS)

  15. Wind electric power generation

    International Nuclear Information System (INIS)

    Koch, M. K.; Wind, L.; Canter, B.; Moeller, T.

    2002-01-01

    The monthly statistics of wind electric power generation in Denmark are compiled from information given by the owners of the private wind turbines. For each wind turbine the name of the site and of the type of turbine is given, and the power generation data are given for the month in question together with the total production in 2000 and 2001. Also the data of operation start are given. On the map of Denmark the sites of the wind turbines are marked. (SM)

  16. Spatial evolution equation of wind wave growth

    Institute of Scientific and Technical Information of China (English)

    WANG; Wei; (王; 伟); SUN; Fu; (孙; 孚); DAI; Dejun; (戴德君)

    2003-01-01

    Based on the dynamic essence of air-sea interactions, a feedback type of spatial evolution equation is suggested to match reasonably the growing process of wind waves. This simple equation involving the dominant factors of wind wave growth is able to explain the transfer of energy from high to low frequencies without introducing the concept of nonlinear wave-wave interactions, and the results agree well with observations. The rate of wave height growth derived in this dissertation is applicable to both laboratory and open sea, which solidifies the physical basis of using laboratory experiments to investigate the generation of wind waves. Thus the proposed spatial evolution equation provides a new approach for the research on dynamic mechanism of air-sea interactions and wind wave prediction.

  17. Wind electric power generation

    International Nuclear Information System (INIS)

    Groening, B.; Koch, M.; Canter, B.; Moeller, T.

    1995-01-01

    The monthly statistics of wind electric power generation in Denmark are compiled from information given by the owners of private wind turbines. For each wind turbine the name of the site and of the type of turbine is given, and the power generation data are given for the month in question together with the total production in 1988 and 1989. Also the data of operation start are given. On the map of Denmark the sites of the wind turbines are marked. The statistics for December 1994 comprise 2328 wind turbines

  18. Wave Generation Theory

    DEFF Research Database (Denmark)

    Frigaard, Peter; Høgedal, Michael; Christensen, Morten

    The intention of this manual is to provide some formulas and techniques which can be used for generating waves in hydraulic laboratories. Both long crested waves (2-D waves) and short crested waves (3-D waves) are considered.......The intention of this manual is to provide some formulas and techniques which can be used for generating waves in hydraulic laboratories. Both long crested waves (2-D waves) and short crested waves (3-D waves) are considered....

  19. Superconducting Wind Turbine Generators

    Directory of Open Access Journals (Sweden)

    Yunying Pan

    2016-08-01

    Full Text Available Wind energy is well known as a renewable energy because its clean and less polluted characteristic, which is the foundation of development modern wind electricity. To find more efficient wind turbine is the focus of scientists around the world. Compared from conventional wind turbines, superconducting wind turbine generators have advantages at zero resistance, smaller size and lighter weight. Superconducting wind turbine will inevitably become the main trends in this area. This paper intends to introduce the basic concept and principle of superconductivity, and compare form traditional wind turbine to obtain superiority, then to summary three proposed machine concept.While superconductivity have difficulty  in modern technology and we also have proposed some challenges in achieving superconducting wind turbine finally.

  20. Ocean Wave Simulation Based on Wind Field.

    Directory of Open Access Journals (Sweden)

    Zhongyi Li

    Full Text Available Ocean wave simulation has a wide range of applications in movies, video games and training systems. Wind force is the main energy resource for generating ocean waves, which are the result of the interaction between wind and the ocean surface. While numerous methods to handle simulating oceans and other fluid phenomena have undergone rapid development during the past years in the field of computer graphic, few of them consider to construct ocean surface height field from the perspective of wind force driving ocean waves. We introduce wind force to the construction of the ocean surface height field through applying wind field data and wind-driven wave particles. Continual and realistic ocean waves result from the overlap of wind-driven wave particles, and a strategy was proposed to control these discrete wave particles and simulate an endless ocean surface. The results showed that the new method is capable of obtaining a realistic ocean scene under the influence of wind fields at real time rates.

  1. Observations of polar patches generated by solar wind Alfvén wave coupling to the dayside magnetosphere

    Directory of Open Access Journals (Sweden)

    P. Prikryl

    1999-04-01

    Full Text Available A long series of polar patches was observed by ionosondes and an all-sky imager during a disturbed period (Kp = 7- and IMF Bz < 0. The ionosondes measured electron densities of up to 9 × 1011 m-3 in the patch center, an increase above the density minimum between patches by a factor of \\sim4.5. Bands of F-region irregularities generated at the equatorward edge of the patches were tracked by HF radars. The backscatter bands were swept northward and eastward across the polar cap in a fan-like formation as the afternoon convection cell expanded due to the IMF By > 0. Near the north magnetic pole, an all-sky imager observed the 630-nm emission patches of a distinctly band-like shape drifting northeastward to eastward. The 630-nm emission patches were associated with the density patches and backscatter bands. The patches originated in, or near, the cusp footprint where they were formed by convection bursts (flow channel events, FCEs structuring the solar EUV-produced photoionization and the particle-produced auroral/cusp ionization by segmenting it into elongated patches. Just equatorward of the cusp footprint Pc5 field line resonances (FLRs were observed by magnetometers, riometers and VHF/HF radars. The AC electric field associated with the FLRs resulted in a poleward-progressing zonal flow pattern and backscatter bands. The VHF radar Doppler spectra indicated the presence of steep electron density gradients which, through the gradient drift instability, can lead to the generation of the ionospheric irregularities found in patches. The FLRs and FCEs were associated with poleward-progressing DPY currents (Hall currents modulated by the IMF By and riometer absorption enhancements. The temporal and spatial characteristics of the VHF backscatter and associated riometer absorptions closely resembled those of poleward moving auroral forms (PMAFs. In the solar wind, IMP 8 observed large amplitude Alfvén waves that were correlated with Pc5 pulsations

  2. The Interaction of Ocean Waves and Wind

    Science.gov (United States)

    Janssen, Peter

    2004-10-01

    Describing in detail the two-way interaction between wind and ocean waves, this book discusses ocean wave evolution in accordance with the energy balance equation. An extensive overview of nonlinear transfer is given, and the role of four-wave interactions in the generation of extreme events as well as the effects on ocean circulation is included. The volume will interest ocean wave modellers, physicists, applied mathematicians, and engineers.

  3. Study of Green Shipping Technologies - Harnessing Wind, Waves and Solar Power in New Generation Marine Propulsion Systems

    Directory of Open Access Journals (Sweden)

    Grzegorz Rutkowski

    2016-12-01

    Full Text Available The purpose and scope of this paper is to describe the complexity of the new generation marine propulsion technologies implemented in the shipping industry to promote green ships concept and change the view of sea transportation to a more ecological and environment-friendly. Harnessing wind, waves and solar power in shipping industry can help the ship’s owners reduce the operational costs. Reducing fuel consumption results in producing less emissions and provides a clean source of renewable energy. Green shipping technologies can also effectively increase the operating range of vessels and help drive sea transportation towards a greener future and contribute to the global reduction of harmful gas emissions from the world's shipping fleets.

  4. Wind power generation

    International Nuclear Information System (INIS)

    Anon.

    1999-01-01

    The monthly statistics of wind electric power generation in Denmark are compiled from information given by the owners of private wind turbines. The data are arranged according to the size of the turbines. For each wind turbine the name of the site and type of turbine is given as well as the production during the last 3 months in 1998, and the total production in 1997 and 1998. Data on the operation is given

  5. Gearless wind power generator

    Energy Technology Data Exchange (ETDEWEB)

    Soederlund, L.; Ridanpaeae, P.; Vihriaelae, H.; Peraelae, R. [Tampere Univ. of Technology (Finland). Lab. of Electricity and Magnetism

    1998-12-31

    During the wind power generator project a design algorithm for a gearless permanent magnet generator with an axially orientated magnetic flux was developed and a 10 kW model machine was constructed. Utilising the test results a variable wind speed system of 100 kW was designed that incorporates a permanent magnet generator, a frequency converter and a fuzzy controller. This system produces about 5-15% more energy than existing types and stresses to the blades are minimised. The type of generator designed in the project represents in general a gearless solution for slow-speed electrical drives. (orig.)

  6. Validation of simulations of an underwater acoustic communication channel characterized by wind-generated surface waves and bubbles

    NARCIS (Netherlands)

    Dol, H.S.; Colin, M.E.G.D.; Ainlie, M.A.; Gerdes, F.; Schäfke, A.; Özkan Sertlekc, H.

    2013-01-01

    This paper shows that it is possible to simulate realistic shallow-water acoustic communication channels using available acoustic propagation models. Key factor is the incorporation of realistic time-dependent sea surface conditions, including both waves and bubbles due to wind.

  7. Linear wind generator

    International Nuclear Information System (INIS)

    Kozarov, A.; Petrov, O.; Antonov, J.; Sotirova, S.; Petrova, B.

    2006-01-01

    The purpose of the linear wind-power generator described in this article is to decrease the following disadvantages of the common wind-powered turbine: 1) large bending and twisting moments to the blades and the shaft, especially when strong winds and turbulence exist; 2) significant values of the natural oscillation period of the construction result in the possibility of occurrence of destroying resonance oscillations; 3) high velocity of the peripheral parts of the rotor creating a danger for birds; 4) difficulties, connected with the installation and the operation on the mountain ridges and passages where the wind energy potential is the largest. The working surfaces of the generator in questions driven by the wind are not connected with a joint shaft but each moves along a railway track with few oscillations. So the sizes of each component are small and their number can be rather large. The mechanical trajectory is not a circle but a closed outline in a vertical plain, which consists of two rectilinear sectors, one above the other, connected in their ends by semi-circumferences. The mechanical energy of each component turns into electrical on the principle of the linear electrical generator. A regulation is provided when the direction of the wind is perpendicular to the route. A possibility of effectiveness is shown through aiming of additional quantities of air to the movable components by static barriers

  8. Observations of polar patches generated by solar wind Alfvén wave coupling to the dayside magnetosphere

    Directory of Open Access Journals (Sweden)

    P. Prikryl

    wind, IMP 8 observed large amplitude Alfvén waves that were correlated with Pc5 pulsations observed by the ground magnetometers, riometers and radars. It is concluded that the FLRs and FCEs that produced patches were driven by solar wind Alfvén waves coupling to the dayside magnetosphere. During a period of southward IMF the dawn-dusk electric field associated with the Alfvén waves modulated the subsolar magnetic reconnection into pulses that resulted in convection flow bursts mapping to the ionospheric footprint of the cusp.

    Key words. Ionosphere (polar ionosphere. Magneto- spheric physics (magnetosphere-ionosphere interactions; polar wind-magnetosphere interactions.

  9. Effects of Deep Water Source-Sink Terms in 3rd generation Wave Model SWAN using different wind data in Black Sea

    Science.gov (United States)

    Kirezci, Cagil; Ozyurt Tarakcioglu, Gulizar

    2016-04-01

    Coastal development in Black Sea has increased in recent years. Therefore, careful monitoring of the storms and verification of numerical tools with reliable data has become important. Previous studies by Kirezci and Ozyurt (2015) investigated extreme events in Black Sea using different wind datasets (NCEP's CFSR and ECMWF's operational datasets) and different numerical tools (SWAN and Wavewatch III). These studies showed that significant effect to results is caused by the deep water source-sink terms (wave growth by wind, deep water dissipation of wave energy (whitecapping) and deep water non-linear wave-wave interactions). According to Timmermans(2015), uncertainty about wind forcing and the process of nonlinear wave-wave interactions are found to be dominant in numerical wave modelling. Therefore, in this study deep water source and sink term solution approaches of 3rd generation numerical tool (SWAN model) are tested, validated and compared using the selected extreme storms in Black Sea. 45 different storms and storm like events observed in Black Sea between years 1994-1999 are selected to use in the models. The storm selection depends on the instrumental wave data (significant wave heights, mean wave period and mean wave direction) obtained in NATO-TU Waves project by the deep water buoy measurements at Hopa, Sinop, Gelendzhik, and wind data (mean and peak wind speeds, storm durations) of the regarding events. 2 different wave growth by wind with the corresponding deep water dissipation terms and 3 different wave -wave interaction terms of SWAN model are used in this study. Wave growth by wind consist of two parts, linear growth which is explained by Cavaleri and Malanotte-Rizzoli(1981),and dominant exponential growth. There are two methods in SWAN model for exponential growth of wave, first one by Snyder et al. (1981), rescaled in terms of friction velocity by Komen et. al (1984) which is derived using driving wind speed at 10m elevation with related drag

  10. Ion acoustic waves in the solar wind

    International Nuclear Information System (INIS)

    Gurnett, D.A.; Frank, L.A.

    1978-01-01

    Plasma wave measurements on the Helios I and 2 spacecraft have revealed the occurrence of electric field turbulence in the solar wind at frequencies between the electron and ion plasma frequencies. Wavelength measurements with the Imp 6 spacecraft now provide strong evidence that these waves are short-wavelength ion acoustic waves which are Doppler-shifted upward in frequency by the motion of the solar wind. Comparison of the Helios results with measurements from the earth-orbiting Imp 6 and 8 spacecraft shows that the ion acoustic turbulence detected in interplanetary space has characteristics essentially identical to those of bursts of electrostatic turbulence generated by protons streaming into the solar wind from the earth's bow shock. In a few cases, enhanced ion acoustic wave intensities have been observed in direct association with abrupt increases in the anisotropy of the solar wind electron distribution. This relationship strongly suggests that the ion acoustic waves detected by Helios far from the earth are produced by an electron heat flux instability, as was suggested by Forslund. Possible related mechanisms which could explain the generation of ion acoustic waves by protons streaming into the solar wind from the earth's bow shock are also considered

  11. Wind and waves: becoming serious Australian industries

    International Nuclear Information System (INIS)

    Anon

    1999-01-01

    Renewable energy is emerging as a critical policy issue in Australia following the Federal Government's 2% target for renewable energy. Adding to the potential for renewable energy in Victoria, Primergy in conjunction with its newly acquired subsidiary Renewable Energy Australia Pacific (REAP) Wind Pty Ltd has secured the exclusive license for the construction, operation and sale of, an advanced technology wind turbine throughout Australia and regional markets. Primergy believes that the potential market for wind generation in Australia could be between 500 to 800 MW or 700 to 1200 wind turbines. The company has also entered into a joint venture with Energetech and is funding 50% of the total cost to build the first wave machine which would be completed at Port Kembla, near Wollongong, by the end of 2000. The wave generator uses an innovative new concept incorporating an highly efficient air driven turbine

  12. Next Generation Wind Turbine

    Energy Technology Data Exchange (ETDEWEB)

    Cheraghi, S. Hossein [Western New England Univ., Springfield, MA (United States); Madden, Frank [FloDesign Wind Turbine Corp., Waltham, MA (United States)

    2012-09-01

    The goal of this collaborative effort between Western New England University's College of Engineering and FloDesign Wind Turbine (FDWT) Corporation to wok on a novel areodynamic concept that could potentially lead to the next generation of wind turbines. Analytical studies and early scale model tests of FDWT's Mixer/Ejector Wind Turbine (MEWT) concept, which exploits jet-age advanced fluid dynamics, indicate that the concept has the potential to significantly reduce the cost of electricity over conventional Horizontal Axis Wind Turbines while reducing land usage. This project involved the design, fabrication, and wind tunnel testing of components of MEWT to provide the research and engineering data necessary to validate the design iterations and optimize system performance. Based on these tests, a scale model prototype called Briza was designed, fabricated, installed and tested on a portable tower to investigate and improve the design system in real world conditions. The results of these scale prototype efforts were very promising and have contributed significantly to FDWT's ongoing development of a product scale wind turbine for deployment in multiple locations around the U.S. This research was mutually beneficial to Western New England University, FDWT, and the DOE by utilizing over 30 student interns and a number of faculty in all efforts. It brought real-world wind turbine experience into the classroom to further enhance the Green Engineering Program at WNEU. It also provided on-the-job training to many students, improving their future employment opportunities, while also providing valuable information to further advance FDWT's mixer-ejector wind turbine technology, creating opportunities for future project innovation and job creation.

  13. Wind Generated Ocean Waves

    DEFF Research Database (Denmark)

    Frigaard, Peter

    2001-01-01

    Book review: I. R. Young, Elsevier Ocean Engineering Series, Vol 2. Elsevier Science, Oxford, UK, 1999, 306 pages, hardbound, ISBN 0-08-043317-0, Dfl. 275,00 (US$ 139.50)......Book review: I. R. Young, Elsevier Ocean Engineering Series, Vol 2. Elsevier Science, Oxford, UK, 1999, 306 pages, hardbound, ISBN 0-08-043317-0, Dfl. 275,00 (US$ 139.50)...

  14. Gearless wind power generator

    Energy Technology Data Exchange (ETDEWEB)

    Soederlund, L.; Ridanpaeae, P.; Vihriaelae, H.; Peraelae, R. [Tampere Univ. of Technology (Finland). Lab. of Electricity and Magnetism

    1998-10-01

    In the project a 100 kW axial flux permanent magnet wind power generator has been designed. The toroidal stator with air gap winding is placed between two rotating discs with permanent magnets. The magnet material is NdBFe due to its excellent magnetic properties compared to other materials. This type of topology enables a very large number of poles compared to conventional machine of the same size. A large number of poles is required to achieve a low rotational speed and consequently a direct driven system. The stator winding is formed by rectangular coils. The end winding is very short leading to small resistive losses. On the other hand, the absence of iron teeth causes eddy current losses in the conductors. These can be restricted to an acceptable level by keeping the wire diameter and flux density small. This means that the number of phases should be large. Several independent three phase systems may be used. The toothless stator also means that the iron losses are small and there exists no cogging torque

  15. Superconducting wind turbine generators

    DEFF Research Database (Denmark)

    Abrahamsen, Asger Bech; Mijatovic, Nenad; Seiler, Eugen

    2010-01-01

    , the main challenge of the superconducting direct drive technology is to prove that the reliability is superior to the alternative drive trains based on gearboxes or permanent magnets. A strategy of successive testing of superconducting direct drive trains in real wind turbines of 10 kW, 100 kW, 1 MW and 10......We have examined the potential of 10 MW superconducting direct drive generators to enter the European offshore wind power market and estimated that the production of about 1200 superconducting turbines until 2030 would correspond to 10% of the EU offshore market. The expected properties of future...... offshore turbines of 8 and 10 MW have been determined from an up-scaling of an existing 5 MW turbine and the necessary properties of the superconducting drive train are discussed. We have found that the absence of the gear box is the main benefit and the reduced weight and size is secondary. However...

  16. Wind Generators and Market Power

    DEFF Research Database (Denmark)

    Misir, Nihat

    price thresholds are significantly higher when the monopolist at the peakload level owns both types of generators. Furthermore, when producing electricity with the peakload generator, the monopolist can avoid facing prices below marginal cost by owning a certain share of the wind generators.......Electricity production from wind generators holds significant importance in European Union’s 20% renewable energy target by 2020. In this paper, I show that ownership of wind generators affects market outcomes by using both a Cournot oligopoly model and a real options model. In the Cournot...... oligopoly model, ownership of the wind generators by owners of fossil-fueled (peakload) generators decreases total peakload production and increases the market price. These effects increase with total wind generation and aggregate wind generator ownership. In the real options model, start up and shut down...

  17. Superconducting wind turbine generators

    International Nuclear Information System (INIS)

    Abrahamsen, A B; Seiler, E; Zirngibl, T; Andersen, N H; Mijatovic, N; Traeholt, C; Pedersen, N F; Oestergaard, J; Noergaard, P B

    2010-01-01

    We have examined the potential of 10 MW superconducting direct drive generators to enter the European offshore wind power market and estimated that the production of about 1200 superconducting turbines until 2030 would correspond to 10% of the EU offshore market. The expected properties of future offshore turbines of 8 and 10 MW have been determined from an up-scaling of an existing 5 MW turbine and the necessary properties of the superconducting drive train are discussed. We have found that the absence of the gear box is the main benefit and the reduced weight and size is secondary. However, the main challenge of the superconducting direct drive technology is to prove that the reliability is superior to the alternative drive trains based on gearboxes or permanent magnets. A strategy of successive testing of superconducting direct drive trains in real wind turbines of 10 kW, 100 kW, 1 MW and 10 MW is suggested to secure the accumulation of reliability experience. Finally, the quantities of high temperature superconducting tape needed for a 10 kW and an extreme high field 10 MW generator are found to be 7.5 km and 1500 km, respectively. A more realistic estimate is 200-300 km of tape per 10 MW generator and it is concluded that the present production capacity of coated conductors must be increased by a factor of 36 by 2020, resulting in a ten times lower price of the tape in order to reach a realistic price level for the superconducting drive train.

  18. Seismic wave generator

    International Nuclear Information System (INIS)

    Devaure, Bernard.

    1982-01-01

    This invention concerns a device for simulating earth tremors. This device includes a seismic wave generator formed of a cylinder, one end of which is closed by one of the walls of a cell containing a soil, the other end being closed by a wall on which are fixed pyrotechnic devices generating shock waves inside the cylinder. These waves are transmitted from the cylinder to the cell through openings made in the cell wall. This device also includes a mechanical device acting as low-pass filter, located inside the cylinder and close to the cell wall [fr

  19. Damping Wind and Wave Loads on a Floating Wind Turbine

    DEFF Research Database (Denmark)

    Christiansen, Søren; Bak, Thomas; Knudsen, Torben

    2013-01-01

    Offshore wind energy capitalizes on the higher and less turbulent wind speeds at sea. To enable deployment of wind turbines in deep-water locations, structures are being explored, where wind turbines are placed on a floating platform. This combined structure presents a new control problem, due......, and we show the influence that both wind speed, wave frequencies and misalignment between wind and waves have on the system dynamics. A new control model is derived that extends standard turbine models to include the hydrodynamics, additional platform degrees of freedom, the platform mooring system...

  20. Generation of electricity by wind power

    Energy Technology Data Exchange (ETDEWEB)

    Golding, E W

    1976-01-01

    Information on wind power is presented concerning the history of windmills; estimation of the energy obtainable from the wind; wind characteristics and distribution; wind power sites; wind surveys; wind flow over hills; measurement of wind velocity; wind structure and its determination; wind data and energy estimation; testing of wind driven ac generators; wind-driven machines; propeller type windmills; plants for isolated premises and small communities; economy of wind power generation; construction costs for large wind-driven generators; relationship of wind power to other power sources; research and development; and international cooperation.

  1. Wave Tank Studies of Phase Velocities of Short Wind Waves

    Science.gov (United States)

    Ermakov, S.; Sergievskaya, I.; Shchegolkov, Yu.

    Wave tank studies of phase velocities of short wind waves have been carried out using Ka-band radar and an Optical Spectrum Analyser. The phase velocities were retrieved from measured radar and optical Doppler shifts, taking into account measurements of surface drift velocities. The dispersion relationship was studied in centimetre (cm)- and millimetre(mm)-scale wavelength ranges at different fetches and wind speeds, both for a clean water surface and for water covered with surfactant films. It is ob- tained that the phase velocities do not follow the dispersion relation of linear capillary- gravity waves, increasing with fetch and, therefore, depending on phase velocities of dominant decimetre (dm)-centimetre-scale wind waves. One thus can conclude that nonlinear cm-mm-scale harmonics bound to the dominant wind waves and propagat- ing with the phase velocities of the decimetric waves are present in the wind wave spectrum. The resulting phase velocities of short wind waves are determined by re- lation between free and bound waves. The relative intensity of the bound waves in the spectrum of short wind waves is estimated. It is shown that this relation depends strongly on the surfactant concentration, because the damping effect due to films is different for free and bound waves; this results to changes of phase velocities of wind waves in the presence of surfactant films. This work was supported by MOD, UK via DERA Winfrith (Project ISTC 1774P) and by RFBR (Project 02-05-65102).

  2. Generators of Modern Wind Turbines

    DEFF Research Database (Denmark)

    Chen, Zhe

    2008-01-01

    In this paper, various types of wind generator configurations, including power electronic grid interfaces, drive trains, are described The performance in power systems is briefed. Then the optimization of generator system is presented. Some investigation results are presented and discussed....

  3. WindWaveFloat (WWF): Final Scientific Report

    Energy Technology Data Exchange (ETDEWEB)

    Weinstein, Alla; Roddier, Dominique; Banister, Kevin

    2012-03-30

    Principle Power Inc. and National Renewable Energy Lab (NREL) have completed a contract to assess the technical and economic feasibility of integrating wave energy converters into the WindFloat, resulting in a new concept called the WindWaveFloat (WWF). The concentration of several devices on one platform could offer a potential for both economic and operational advantages. Wind and wave energy converters can share the electrical cable and power transfer equipment to transport the electricity to shore. Access to multiple generation devices could be simplified, resulting in cost saving at the operational level. Overall capital costs may also be reduced, provided that the design of the foundation can be adapted to multiple devices with minimum modifications. Finally, the WindWaveFloat confers the ability to increase energy production from individual floating support structures, potentially leading to a reduction in levelized energy costs, an increase in the overall capacity factor, and greater stability of the electrical power delivered to the grid. The research conducted under this grant investigated the integration of several wave energy device types into the WindFloat platform. Several of the resulting system designs demonstrated technical feasibility, but the size and design constraints of the wave energy converters (technical and economic) make the WindWaveFloat concept economically unfeasible at this time. Not enough additional generation could be produced to make the additional expense associated with wave energy conversion integration into the WindFloat worthwhile.

  4. Superconducting Wind Turbine Generators

    DEFF Research Database (Denmark)

    Mijatovic, Nenad

    A HTS machine could be a way to address some of the technical barriers offshore wind energy is about to face. Due to the superior power density of HTS machines, this technology could become a milestone on which many, including the wind industry, will rely in the future. The work presented...... in this thesis is a part of a larger endeavor, the Superwind project that focused on identifying the potentials that HTS machines could offer to the wind industry and addressing some of the challenges in the process. In order to identify these challenges, I have design and constructed a HTS machine experimental...... setup which is made to serve as precursor, leading towards an optimized HTS machine concept proposed for wind turbines. In part, the work presented in this thesis will focus on the description of the experimental setup and reasoning behind the choices made during the design. The setup comprises from...

  5. Power recovery method for testing the efficiency of the ECD of an integrated generation unit for offshore wind power and ocean wave energy

    Institute of Scientific and Technical Information of China (English)

    CHEN WeiXing; GAO Feng; MENG XiangDun; REN AnYe; HU Yan

    2017-01-01

    Offshore wind power and ocean wave energy are clean,renewable and rich resources.The integrated generation unit for the two kinds of energy is introduced.The energy conversion device (ECD) is utilized to convert the mechanical energy absorbed from the wind power and wave energy into the hydraulic energy,the conversion efficiency of which is significant.In this paper,a power recovery method for testing the efficiency of the ECD is proposed.A simulation desktop is developed to validate the proposed method.The efficiency of the ECD is influenced by the hydraulic cylinders and the mechanical transmission.Here,the static efficiency of the hydraulic cylinders of the ECD is tested first.The results show that the static mechanical efficiency is about 95 % and that the volumetric efficiency is over 99%.To test the effects induced by the mechanical transmission of the ECD,each hydraulic cylinder of the ECD is substituted with two springs.Then the power loss of the ECDM under different rotational speeds is obtained.Finally,a test platform is built and the efficiency of the ECD under different rotational speeds and pressures is obtained.The results show that the efficiency is about 80%.

  6. Wind wave source functions in opposing seas

    KAUST Repository

    Langodan, Sabique

    2015-08-26

    The Red Sea is a challenge for wave modeling because of its unique two opposed wave systems, forced by opposite winds and converging at its center. We investigate the different physical aspects of wave evolution and propagation in the convergence zone. The two opposing wave systems have similar amplitude and frequency, each driven by the action of its own wind. Wave patterns at the centre of the Red Sea, as derived from extensive tests and intercomparison between model and measured data, suggest that the currently available wave model source functions may not properly represent the evolution of the local fields that appear to be characterized by a less effective wind input and an enhanced white-capping. We propose and test a possible simple solution to improve the wave-model simulation under opposing winds and waves condition. This article is protected by copyright. All rights reserved.

  7. Wave and tidal generation devices reliability and availability

    CERN Document Server

    Tavner, Peter John

    2017-01-01

    To some extent the wave and tidal generation industry is following in the wake of the wind industry, learning from the growing experience of offshore wind farm deployment. This book combines wind industry lessons with wave and tidal field knowledge to explore the main reliability and availability issues facing this growing industry.

  8. Turbulence generation by waves

    Energy Technology Data Exchange (ETDEWEB)

    Kaftori, D.; Nan, X.S.; Banerjee, S. [Univ. of California, Santa Barbara, CA (United States)

    1995-12-31

    The interaction between two-dimensional mechanically generated waves, and a turbulent stream was investigated experimentally in a horizontal channel, using a 3-D LDA synchronized with a surface position measuring device and a micro-bubble tracers flow visualization with high speed video. Results show that although the wave induced orbital motion reached all the way to the wall, the characteristics of the turbulence wall structures and the turbulence intensity close to the wall were not altered. Nor was the streaky nature of the wall layer. On the other hand, the mean velocity profile became more uniform and the mean friction velocity was increased. Close to the free surface, the turbulence intensity was substantially increased as well. Even in predominantly laminar flows, the introduction of 2-D waves causes three dimensional turbulence. The turbulence enhancement is found to be proportional to the wave strength.

  9. Generation of electricity from wind

    International Nuclear Information System (INIS)

    Debroy, S.K.; Behera, S.; Murty, J.S.

    1997-01-01

    Bulk power can be generated by using a chain of wind mills with the current level of technology. Wind turbine technology has improved considerably resulting in better efficiency, availability and capacity factor including a significant reduction in the cost of manufacture and installation

  10. Superconducting wind turbine generators

    DEFF Research Database (Denmark)

    Mijatovic, Nenad

    cryostat design, where a concept with 20 W of heat transfer is achieved. Following the setup description, the focus turns to the electromagnetic design of the HTS machine. Particularly, an approach to increase the performance of HTS coils and the influence of the armature reaction to the HTS field winding...... magnetic characteristic with respect to the critical current. I have showed that the potential for the reduction of HTS conductor can be significant, if the coils are placed strategically, whereby the coils wound with BSCCO performed 40% better depending on the placement in the field winding. The 2G coils...... were less sensitive to the placement which made them particularly useful for high magnetic field regions in the eld winding. The second design approach proposed and tested was to use multiple current supplies which allowed each coil to operate close to its critical current. I have demonstrated...

  11. Magnet Free Generators - 3rd Generation Wind Turbine Generators

    DEFF Research Database (Denmark)

    Jensen, Bogi Bech; Mijatovic, Nenad; Henriksen, Matthew Lee

    2013-01-01

    This paper presents an introduction to superconducting wind turbine generators, which are often referred to as 3rd generation wind turbine generators. Advantages and challenges of superconducting generators are presented with particular focus on possible weight and efficiency improvements. A comp...

  12. Offshore wind generators: realization?

    International Nuclear Information System (INIS)

    Roche, Catherine

    2012-01-01

    The author discusses the French legal context for the different aspects of the development of offshore wind farms in France: procedures related to electricity production installations (authorization or tender like what has been done for six sites), other administrative authorizations, and connection to the grid. Then, she addresses the various constraints: environmental, social and technical constraints (protected marine areas, constraints related to the tendering process), coast planning documents, tax policy. She finally discusses the installation dismantling

  13. Wind-wave amplification mechanisms: possible models for steep wave events in finite depth

    Directory of Open Access Journals (Sweden)

    P. Montalvo

    2013-11-01

    Full Text Available We extend the Miles mechanism of wind-wave generation to finite depth. A β-Miles linear growth rate depending on the depth and wind velocity is derived and allows the study of linear growth rates of surface waves from weak to moderate winds in finite depth h. The evolution of β is plotted, for several values of the dispersion parameter kh with k the wave number. For constant depths we find that no matter what the values of wind velocities are, at small enough wave age the β-Miles linear growth rates are in the known deep-water limit. However winds of moderate intensities prevent the waves from growing beyond a critical wave age, which is also constrained by the water depth and is less than the wave age limit of deep water. Depending on wave age and wind velocity, the Jeffreys and Miles mechanisms are compared to determine which of them dominates. A wind-forced nonlinear Schrödinger equation is derived and the Akhmediev, Peregrine and Kuznetsov–Ma breather solutions for weak wind inputs in finite depth h are obtained.

  14. Identification of wind fields for wave modeling near Qatar

    Science.gov (United States)

    Nayak, Sashikant; Balan Sobhana, Sandeepan; Panchang, Vijay

    2016-04-01

    Due to the development of coastal and offshore infrastructure in and around the Arabian Gulf, a large semi-enclosed sea, knowledge of met-ocean factors like prevailing wind systems, wind generated waves, and currents etc. are of great importance. Primarily it is important to identify the wind fields that are used as forcing functions for wave and circulation models for hindcasting and forecasting purposes. The present study investigates the effects of using two sources of wind-fields on the modeling of wind-waves in the Arabian Gulf, in particular near the coastal regions of Qatar. Two wind sources are considered here, those obtained from ECMWF and those generated by us using the WRF model. The wave model SWAN was first forced with the 6 hourly ERA Interim daily winds (from ECMWF) having spatial resolution of 0.125°. For the second option, wind fields were generated by us using the mesoscale wind model (WRF) with a high spatial resolution (0.1°) at every 30 minute intervals. The simulations were carried out for a period of two months (7th October-7th December, 2015) during which measurements were available from two moored buoys (deployed and operated by the Qatar Meteorological Department), one in the north of Qatar ("Qatar North", in water depth of 58.7 m) and other in the south ("Shiraouh Island", in water depth of 16.64 m). This period included a high-sea event on 11-12th of October, recorded by the two buoys where the significant wave heights (Hs) reached as high as 2.9 m (i.e. max wave height H ~ 5.22 m) and 1.9 (max wave height H ~ 3.4 m) respectively. Model results were compared with the data for this period. The scatter index (SI) of the Hs simulated using the WRF wind fields and the observed Hs was found to be about 30% and 32% for the two buoys (total period). The observed Hs were generally reproduced but there was consistent underestimation. (Maximum 27% for the high-sea event). For the Hs obtained with ERA interim wind fields, the underestimation was

  15. WIND observations of coherent electrostatic waves in the solar wind

    Directory of Open Access Journals (Sweden)

    A. Mangeney

    1999-03-01

    Full Text Available The time domain sampler (TDS experiment on WIND measures electric and magnetic wave forms with a sampling rate which reaches 120 000 points per second. We analyse here observations made in the solar wind near the Lagrange point L1. In the range of frequencies above the proton plasma frequency fpi and smaller than or of the order of the electron plasma frequency fpe, TDS observed three kinds of electrostatic (e.s. waves: coherent wave packets of Langmuir waves with frequencies f ~ fpe, coherent wave packets with frequencies in the ion acoustic range fpi < f < fpe, and more or less isolated non-sinusoidal spikes lasting less than 1 ms. We confirm that the observed frequency of the low frequency (LF ion acoustic wave packets is dominated by the Doppler effect: the wavelengths are short, 10 to 50 electron Debye lengths λD. The electric field in the isolated electrostatic structures (IES and in the LF wave packets is more or less aligned with the solar wind magnetic field. Across the IES, which have a spatial width of the order of ~ 25λD, there is a small but finite electric potential drop, implying an average electric field generally directed away from the Sun. The IES wave forms, which have not been previously reported in the solar wind, are similar, although with a smaller amplitude, to the weak double layers observed in the auroral regions, and to the electrostatic solitary waves observed in other regions in the magnetosphere. We have also studied the solar wind conditions which favour the occurrence of the three kinds of waves: all these e.s. waves are observed more or less continuously in the whole solar wind (except in the densest regions where a parasite prevents the TDS observations. The type (wave packet or IES of the observed LF waves is mainly determined by the proton temperature and by the direction of the magnetic field, which themselves depend on the latitude of WIND with respect to the heliospheric current sheet.Key words

  16. WIND observations of coherent electrostatic waves in the solar wind

    Directory of Open Access Journals (Sweden)

    A. Mangeney

    Full Text Available The time domain sampler (TDS experiment on WIND measures electric and magnetic wave forms with a sampling rate which reaches 120 000 points per second. We analyse here observations made in the solar wind near the Lagrange point L1. In the range of frequencies above the proton plasma frequency fpi and smaller than or of the order of the electron plasma frequency fpe, TDS observed three kinds of electrostatic (e.s. waves: coherent wave packets of Langmuir waves with frequencies f ~ fpe, coherent wave packets with frequencies in the ion acoustic range fpi < f < fpe, and more or less isolated non-sinusoidal spikes lasting less than 1 ms. We confirm that the observed frequency of the low frequency (LF ion acoustic wave packets is dominated by the Doppler effect: the wavelengths are short, 10 to 50 electron Debye lengths λD. The electric field in the isolated electrostatic structures (IES and in the LF wave packets is more or less aligned with the solar wind magnetic field. Across the IES, which have a spatial width of the order of ~ 25λD, there is a small but finite electric potential drop, implying an average electric field generally directed away from the Sun. The IES wave forms, which have not been previously reported in the solar wind, are similar, although with a smaller amplitude, to the weak double layers observed in the auroral regions, and to the electrostatic solitary waves observed in other regions in the magnetosphere. We have also studied the solar wind conditions which favour the occurrence of the three kinds of waves: all these e.s. waves are observed more or less continuously in the whole solar wind (except in the densest regions where a parasite prevents the TDS observations. The type (wave packet or IES of the observed LF waves is mainly determined

  17. Electrostatic Solitary Waves in the Solar Wind: Evidence for Instability at Solar Wind Current Sheets

    Science.gov (United States)

    Malaspina, David M.; Newman, David L.; Wilson, Lynn Bruce; Goetz, Keith; Kellogg, Paul J.; Kerstin, Kris

    2013-01-01

    A strong spatial association between bipolar electrostatic solitary waves (ESWs) and magnetic current sheets (CSs) in the solar wind is reported here for the first time. This association requires that the plasma instabilities (e.g., Buneman, electron two stream) which generate ESWs are preferentially localized to solar wind CSs. Distributions of CS properties (including shear angle, thickness, solar wind speed, and vector magnetic field change) are examined for differences between CSs associated with ESWs and randomly chosen CSs. Possible mechanisms for producing ESW-generating instabilities at solar wind CSs are considered, including magnetic reconnection.

  18. Wave Tank Studies of Strong Modulation of Wind Ripples Due To Long Waves

    Science.gov (United States)

    Ermakov, S.; Sergievskaya, I.; Shchegolkov, Yu.

    Modulation of wind capillary-gravity ripples due to long waves has been studied in wave tank experiment at low wind speeds using Ka-band radar. The experiments were carried out both for clean water and the water surface covered with surfactant films. It is obtained that the modulation of radar signals is quite strong and can increase with surfactant concentration and fetch. It is shown that the hydrodynamic Modulation Transfer Function (MTF) calculated for free wind ripples and taking into account the kinematic (straining) effect, variations of the wind stress and variations of surfactant concentration strongly underestimates experimental MTF-values. The effect of strong modulation is assumed to be connected with nonlinear harmonics of longer dm-cm- scale waves - bound waves ("parasitic ripples"). The intensity of bound waves depends strongly on the amplitude of decimetre-scale waves, therefore even weak modulation of the dm-scale waves due to long waves results to strong ("cascade") modulation of bound waves. Modulation of the system of "free/bound waves" is estimated using results of wave tank studies of bound waves generation and is shown to be in quali- tative agreement with experiment. This work was supported by MOD, UK via DERA Winfrith (Project ISTC 1774P) and by RFBR (Project 02-05-65102).

  19. Large superconducting wind turbine generators

    DEFF Research Database (Denmark)

    Abrahamsen, Asger Bech; Magnusson, Niklas; Jensen, Bogi Bech

    2012-01-01

    and the rotation speed is lowered in order to limit the tip speed of the blades. The ability of superconducting materials to carry high current densities with very small losses might facilitate a new class of generators operating with an air gap flux density considerably higher than conventional generators...... and thereby having a smaller size and weight [1, 2]. A 5 MW superconducting wind turbine generator forms the basics for the feasibility considerations, particularly for the YBCO and MgB2 superconductors entering the commercial market. Initial results indicate that a 5 MW generator with an active weight of 34...

  20. Predictability and Variability of Wave and Wind

    DEFF Research Database (Denmark)

    Chozas, Julia Fernandez; Kofoed, Jens Peter; Sørensen, Hans Christian

    This project covers two fields of study: a) Wave energy predictability and electricity markets. b) Variability of the power output of WECs in diversified systems : diversified renewable systems with wave and offshore wind production. See page 2-4 in the report for a executive summery....

  1. The noise generated by wind turbines

    International Nuclear Information System (INIS)

    Anon.

    2012-01-01

    Sound propagation damps down with distance and varies according to different parameters like wind direction and temperature. This article begins by recalling the basic physics of sound wave propagation and gives a list of common noises and corresponding decibels. The habitual noise of wind turbines 500 m away is 35 decibels which ranks it between a quiet bedroom (30 decibels) and a calm office (40 decibels). The question about whether wind turbines are a noise nuisance is all the more difficult as the feeling of a nuisance is so objective and personal. Any project of wind turbines requires a thorough study of its estimated acoustic impact. This study is a 3 step approach: first the initial noise environment is measured, secondly the propagation of the sound generated by the wind turbine farm is modelled and adequate mitigation measures are proposed to comply the law. The law stipulates that the increase of noise must be less than 5 db during daylight and less than 3 db during night. (A.C.)

  2. Effect of phase coupling on surface amplitude distribution of wind waves

    Digital Repository Service at National Institute of Oceanography (India)

    Varkey, M.J.

    Nonlinear features of wind generated surface waves are considered here to be caused by nonrandomness (non-Uniform) in the phase spectrum. Nonrandomness in recorded waves, if present, would be generally obscured within the error level of observations...

  3. A time-localized response of wave growth process under turbulent winds

    Directory of Open Access Journals (Sweden)

    Z. Ge

    2007-06-01

    Full Text Available Very short time series (with lengths of approximately 40 s or 5~7 wave periods of wind velocity fluctuations and wave elevation were recorded simultaneously and investigated using the wavelet bispectral analysis. Rapid changes in the wave and wind spectra were detected, which were found to be intimately related to significant energy transfers through transient quadratic wind-wave and wave-wave interactions. A possible pattern of energy exchange between the wind and wave fields was further deduced. In particular, the generation and variation of the strong wave-induced perturbation velocity in the wind can be explained by the strengthening and diminishing of the associated quadratic interactions, which cannot be unveiled by linear theories. On small time scales, the wave-wave quadratic interactions were as active and effective in transferring energy as the wind-wave interactions. The results also showed that the wind turbulence was occasionally effective in transferring energy between the wind and the wave fields, so that the background turbulence in the wind cannot be completely neglected. Although these effects are all possibly significant over short times, the time-localized growth of the wave spectrum may not considerably affect the long-term process of wave development.

  4. Laboratory generation of gravitational waves

    International Nuclear Information System (INIS)

    Pinto, I.M.; Rotoli, G.

    1988-01-01

    The authors have performed calculations on the basic type of gravitational wave electromagnetic laboratory generators. Their results show that laboratory generations of gravitational wave is at limit of state-of-the-art of present-day giant electromagnetic field generation

  5. Wind, Wave, and Tidal Energy Without Power Conditioning

    Science.gov (United States)

    Jones, Jack A.

    2013-01-01

    Most present wind, wave, and tidal energy systems require expensive power conditioning systems that reduce overall efficiency. This new design eliminates power conditioning all, or nearly all, of the time. Wind, wave, and tidal energy systems can transmit their energy to pumps that send high-pressure fluid to a central power production area. The central power production area can consist of a series of hydraulic generators. The hydraulic generators can be variable displacement generators such that the RPM, and thus the voltage, remains constant, eliminating the need for further power conditioning. A series of wind blades is attached to a series of radial piston pumps, which pump fluid to a series of axial piston motors attached to generators. As the wind is reduced, the amount of energy is reduced, and the number of active hydraulic generators can be reduced to maintain a nearly constant RPM. If the axial piston motors have variable displacement, an exact RPM can be maintained for all, or nearly all, wind speeds. Analyses have been performed that show over 20% performance improvements with this technique over conventional wind turbines

  6. Study on wave power generation of electricity using torsion arc blade type horizontal axis wind turbine; Nejire enko yokugata suihei jiku fusha wo mochiita haryoku hatsuden ni kansuru kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Kojima, N; Kishimura, K [Meiji University, Tokyo (Japan)

    1996-10-27

    Windmilling characteristics of a combination of a torsion arc blade type (TABT) horizontal axis wind turbine and a reverse torsion arc blade type (RTABT) horizontal axis wind turbine were evaluated in a wave activated power generation experiment. The TABT wind turbine had six blades, and the front and rear parts of the blade were twisted in the same direction, which caused the direction of rotor rotation to change as the direction of wind along the shaft changed. The RTABT wind turbine had twelve blades, and the front and rear parts of the blade were twisted reverse to each other, which allowed the direction of rotor rotation to stay constant even in the presence of wind direction reversal. To keep the direction of rotor rotation unchanged in the presence of flow direction reversal along the power generating turbine shaft, a single-stage type RTABT wind turbine and a double-stage type were used, the double-stage type being a series connection of a first-stage RTABT (for blowout and suction) and second-stage TABT (for blowout only). Both single-type and double-type rotated in the same direction irrespective of the direction of air flow. The output of the double type was obtained by adding up the values obtained from the individual turbines. The double type was two to three times higher in efficiency than the single type in turbine revolution and power output. 2 refs., 13 figs.

  7. Turbulent Structure Under Short Fetch Wind Waves

    Science.gov (United States)

    2015-12-01

    maximum 200 words ) Momentum transfer from wind forcing into the ocean is complicated by the presence of surface waves. Wind momentum and energy are...1,520 m from the mouth of the river to the deployment site ). Map created in Google Earth, October 12, 2015, http://www.google.com/earth/. 33...Doppler processing electronics for each transducer uses 14 bit analog to digital converter to digitize the 1.2 MHz acoustic frequency from the four

  8. LANGMUIR WAVE DECAY IN INHOMOGENEOUS SOLAR WIND PLASMAS: SIMULATION RESULTS

    Energy Technology Data Exchange (ETDEWEB)

    Krafft, C. [Laboratoire de Physique des Plasmas, Ecole Polytechnique, F-91128 Palaiseau Cedex (France); Volokitin, A. S. [IZMIRAN, Troitsk, 142190, Moscow (Russian Federation); Krasnoselskikh, V. V., E-mail: catherine.krafft@u-psud.fr [Laboratoire de Physique et Chimie de l’Environnement et de l’Espace, 3A Av. de la Recherche Scientifique, F-45071 Orléans Cedex 2 (France)

    2015-08-20

    Langmuir turbulence excited by electron flows in solar wind plasmas is studied on the basis of numerical simulations. In particular, nonlinear wave decay processes involving ion-sound (IS) waves are considered in order to understand their dependence on external long-wavelength plasma density fluctuations. In the presence of inhomogeneities, it is shown that the decay processes are localized in space and, due to the differences between the group velocities of Langmuir and IS waves, their duration is limited so that a full nonlinear saturation cannot be achieved. The reflection and the scattering of Langmuir wave packets on the ambient and randomly varying density fluctuations lead to crucial effects impacting the development of the IS wave spectrum. Notably, beatings between forward propagating Langmuir waves and reflected ones result in the parametric generation of waves of noticeable amplitudes and in the amplification of IS waves. These processes, repeated at different space locations, form a series of cascades of wave energy transfer, similar to those studied in the frame of weak turbulence theory. The dynamics of such a cascading mechanism and its influence on the acceleration of the most energetic part of the electron beam are studied. Finally, the role of the decay processes in the shaping of the profiles of the Langmuir wave packets is discussed, and the waveforms calculated are compared with those observed recently on board the spacecraft Solar TErrestrial RElations Observatory and WIND.

  9. Wave Generation in Physical Models

    DEFF Research Database (Denmark)

    Andersen, Thomas Lykke; Frigaard, Peter

    The present book describes the most important aspects of wave generation techniques in physical models. Moreover, the book serves as technical documentation for the wave generation software AwaSys 6, cf. Aalborg University (2012). In addition to the two main authors also Tue Hald and Michael...

  10. Waves in the Red Sea: Response to monsoonal and mountain gap winds

    KAUST Repository

    Ralston, David K.

    2013-08-01

    An unstructured grid, phase-averaged wave model forced with winds from a high resolution atmospheric model is used to evaluate wind wave conditions in the Red Sea over an approximately 2-year period. The Red Sea lies in a narrow rift valley, and the steep topography surrounding the basin steers the dominant wind patterns and consequently the wave climate. At large scales, the model results indicated that the primary seasonal variability in waves was due to the monsoonal wind reversal. During the winter, monsoon winds from the southeast generated waves with mean significant wave heights in excess of 2. m and mean periods of 8. s in the southern Red Sea, while in the northern part of the basin waves were smaller, shorter period, and from northwest. The zone of convergence of winds and waves typically occurred around 19-20°N, but the location varied between 15 and 21.5°N. During the summer, waves were generally smaller and from the northwest over most of the basin. While the seasonal winds oriented along the axis of the Red Sea drove much of the variability in the waves, the maximum wave heights in the simulations were not due to the monsoonal winds but instead were generated by localized mountain wind jets oriented across the basin (roughly east-west). During the summer, a mountain wind jet from the Tokar Gap enhanced the waves in the region of 18 and 20°N, with monthly mean wave heights exceeding 2. m and maximum wave heights of 14. m during a period when the rest of the Red Sea was relatively calm. Smaller mountain gap wind jets along the northeast coast created large waves during the fall and winter, with a series of jets providing a dominant source of wave energy during these periods. Evaluation of the wave model results against observations from a buoy and satellites found that the spatial resolution of the wind model significantly affected the quality of the wave model results. Wind forcing from a 10-km grid produced higher skills for waves than winds from a

  11. Wind and waves in extreme hurricanes

    NARCIS (Netherlands)

    Holthuijsen, L.H.; Powell, M.D.; Pietrzak, J.D.

    2012-01-01

    Waves breaking at the ocean surface are important to the dynamical, chemical and biological processes at the air-sea interface. The traditional view is that the white capping and aero-dynamical surface roughness increase with wind speed up to a limiting value. This view is fundamental to hurricane

  12. Wind wave source functions in opposing seas

    KAUST Repository

    Langodan, Sabique; Cavaleri, Luigi; Viswanadhapalli, Yesubabu; Hoteit, Ibrahim

    2015-01-01

    that the currently available wave model source functions may not properly represent the evolution of the local fields that appear to be characterized by a less effective wind input and an enhanced white-capping. We propose and test a possible simple solution

  13. Electromagnetic Cyclotron Waves in the Solar Wind: Wind Observation and Wave Dispersion Analysis

    Science.gov (United States)

    Jian, L. K.; Moya, P. S.; Vinas, A. F.; Stevens, M.

    2016-01-01

    Wind observed long-lasting electromagnetic cyclotron waves near the proton cyclotron frequency on 11 March 2005, in the descending part of a fast wind stream. Bi-Maxwellian velocity distributions are fitted for core protons, beam protons, and alpha-particles. Using the fitted plasma parameters we conduct kinetic linear dispersion analysis and find ion cyclotron and/or firehose instabilities grow in six of 10 wave intervals. After Doppler shift, some of the waves have frequency and polarization consistent with observation, thus may be correspondence to the cyclotron waves observed.

  14. The Red Sea: An Arena for Wind-Wave Modeling in Enclosed Seas

    KAUST Repository

    Langodan, Sabique

    2016-12-01

    Wind and waves play a major role in important ocean dynamical processes, such as the exchange of heat, momentum and gases between atmosphere and ocean, that greatly contributes to the earth climate and marine lives. Knowledge on wind and wave weather and climate is crucial for a wide range of applications, including oceanographic studies, maritime activities and ocean engineering. Despite being one of the important world shipping routes, the wind-wave characteristics in the Red Sea are yet to be fully explored. Because of the scarcity of waves data in the Red Sea, numerical models become crucial and provide very powerful tools to extrapolate wind and wave data in space, and backward and forward in time. Unlike open oceans, enclosed basins wave have different characteristics, mainly because of their local generation processes. The complex orography on both sides of the Red Sea makes the local wind, and consequently wave, modeling very challenging. This thesis considers the modeling of wind-wave characteristics in the Red Sea, including their climate variability and trends using state-of-the-art numerical models and all available observations. Different approaches are investigated to model and understand the general and unusual wind and wave conditions in the basin using standard global meteorological products and customised regional wind and wave models. After studying and identifying the main characteristics of the wind-wave variability in the Red Sea, we demonstrate the importance of generating accurate atmospheric forcing through data assimilation for reliable wave simulations. In particular, we show that the state-of-the-art physical formulation of wave models is not suitable to model the unique situation of the two opposing wind-waves systems in the Red Sea Convergence Zone, and propose and successfully test a modification to the input and white-capping source functions to address this problem. We further investigate the climate variability and trends of wind

  15. Wind Generation Feasibility Study in Bethel, AK

    Energy Technology Data Exchange (ETDEWEB)

    Tom Humphrey, YKHC; Lance Kincaid, EMCOR Energy & Technologies

    2004-07-31

    This report studies the wind resources in the Yukon-Kuskokwim Health Corporation (YKHC) region, located in southwestern Alaska, and the applicability of wind generation technologies to YKHC facilities.

  16. Conditional prediction intervals of wind power generation

    DEFF Research Database (Denmark)

    Pinson, Pierre; Kariniotakis, Georges

    2010-01-01

    A generic method for the providing of prediction intervals of wind power generation is described. Prediction intervals complement the more common wind power point forecasts, by giving a range of potential outcomes for a given probability, their so-called nominal coverage rate. Ideally they inform...... on the characteristics of prediction errors for providing conditional interval forecasts. By simultaneously generating prediction intervals with various nominal coverage rates, one obtains full predictive distributions of wind generation. Adapted resampling is applied here to the case of an onshore Danish wind farm...... to the case of a large number of wind farms in Europe and Australia among others is finally discussed....

  17. A high-resolution assessment of wind and wave energy potentials in the Red Sea

    KAUST Repository

    Langodan, Sabique

    2016-08-24

    This study presents an assessment of the potential for harvesting wind and wave energy from the Red Sea based on an 18-year high-resolution regional atmospheric reanalysis recently generated using the Advanced Weather Research Forecasting model. This model was initialized with ERA-Interim global data and the Red Sea reanalysis was generated using a cyclic three-dimensional variational approach assimilating available data in the region. The wave hindcast was generated using WAVEWATCH III on a 5 km resolution grid, forced by the Red Sea reanalysis surface winds. The wind and wave products were validated against data from buoys, scatterometers and altimeters. Our analysis suggests that the distribution of wind and wave energy in the Red Sea is inhomogeneous and is concentrated in specific areas, characterized by various meteorological conditions including weather fronts, mesoscale vortices, land and sea breezes and mountain jets. A detailed analysis of wind and wave energy variation was performed at three hotspots representing the northern, central and southern parts of the Red Sea. Although there are potential sites for harvesting wind energy from the Red Sea, there are no potential sites for harvesting wave energy because wave energy in the Red Sea is not strong enough for currently available wave energy converters. Wave energy should not be completely ignored, however, at least from the perspective of hybrid wind-wave projects. (C) 2016 Elsevier Ltd. All rights reserved.

  18. Wave and Wind Model Performance Metrics Tools

    Science.gov (United States)

    Choi, J. K.; Wang, D. W.

    2016-02-01

    Continual improvements and upgrades of Navy ocean wave and wind models are essential to the assurance of battlespace environment predictability of ocean surface wave and surf conditions in support of Naval global operations. Thus, constant verification and validation of model performance is equally essential to assure the progress of model developments and maintain confidence in the predictions. Global and regional scale model evaluations may require large areas and long periods of time. For observational data to compare against, altimeter winds and waves along the tracks from past and current operational satellites as well as moored/drifting buoys can be used for global and regional coverage. Using data and model runs in previous trials such as the planned experiment, the Dynamics of the Adriatic in Real Time (DART), we demonstrated the use of accumulated altimeter wind and wave data over several years to obtain an objective evaluation of the performance the SWAN (Simulating Waves Nearshore) model running in the Adriatic Sea. The assessment provided detailed performance of wind and wave models by using cell-averaged statistical variables maps with spatial statistics including slope, correlation, and scatter index to summarize model performance. Such a methodology is easily generalized to other regions and at global scales. Operational technology currently used by subject matter experts evaluating the Navy Coastal Ocean Model and the Hybrid Coordinate Ocean Model can be expanded to evaluate wave and wind models using tools developed for ArcMAP, a GIS application developed by ESRI. Recent inclusion of altimeter and buoy data into a format through the Naval Oceanographic Office's (NAVOCEANO) quality control system and the netCDF standards applicable to all model output makes it possible for the fusion of these data and direct model verification. Also, procedures were developed for the accumulation of match-ups of modelled and observed parameters to form a data base

  19. Proton beam generation of whistler waves in the earth's foreshock

    Science.gov (United States)

    Wong, H. K.; Goldstein, M. L.

    1987-01-01

    It is shown that proton beams, often observed upstream of the earth's bow shock and associated with the generation of low-frequency hydromagnetic fluctuations, are also capable of generating whistler waves. The waves can be excited by an instability driven by two-temperature streaming Maxwellian proton distributions which have T (perpendicular)/T(parallel) much greater than 1. It can also be excited by gyrating proton beam distributions. These distributions generate whistler waves with frequencies ranging from 10 to 100 times the proton cyclotron frequency (in the solar wind reference frame) and provide another mechanism for generating the '1-Hz' waves often seen in the earth's foreshock.

  20. Proton beam generation of whistler waves in the Earth's foreshock

    International Nuclear Information System (INIS)

    Wong, H.K.; Goldstein, M.L.

    1987-01-01

    We show that proton beams, often observed upstream of the Earth's bow shock and associated with the generation of low-frequency hydromagnetic fluctuations, are also capable of generating whistler waves. The waves can be excited by an instability driven by two-temperature streaming Maxwellian proton distributions which have T/sub perpendicular//T/sub parallel/>>1. It can also be excited by gyrating proton beam distributions. These distributions generate whistler waves with frequencies ranging from 10 to 100 times the proton cyclotron frequency (in the solar wind reference frame) and provide another mechanism for generating the ''1-Hz'' waves often seen in the Earth's foreshock

  1. Simulation of Lightning Overvoltage Distribution on Stator Windings of Wind Turbine Generators

    Institute of Scientific and Technical Information of China (English)

    LIU Rong; LIU Xue-zhong; WANG Ying; LI Dan-dan

    2011-01-01

    This paper analyzes lightning surge on the stator windings of wind turbine generators. The path of lightning in the wind turbines was analyzed. An equivalent circuit model for megawatt direct-driven wind turbine system was developed, in which high-frequency distributed parameters of the blade conducts, tower, power cables and stator windings of generator were calculated based on finite element method, and the models of converter, grounding, loads, surge protection devices and power grid were established. The voltage distribution along stator windings, when struck by lightning with 10/350 ~ts wave form and different amplitude current between 50 kA and 200 kA, was simulated u- sing electro-magnetic transient analysis method. The simulated results show that the highest coil-to-core voltage peak appears on the last coil or near the neutral of stator windings, and the voltage distribution along the windings is non- uniform initially. The voltage drops of each coil fall from first to last coil, and the highest voltage drop appears on the first coil. The insulation damage may occur on the windings under lightning overvoltage. The surge arresters can re- strain the lightning surge in effect and protect the insulation. The coil-to-core voltage in the end of windings is nearly 19.5 kV under the 200 kA lightning current without surge arresters on the terminal of generator, but is only 2.7 kV with arresters.

  2. Corotating pressure waves without streams in the solar wind

    International Nuclear Information System (INIS)

    Burlaga, L.F.

    1983-01-01

    Voyager 1 and 2 magnetic field and plasma data are presented which demonstrate the existence of large scale, corotating, non-linear pressure waves between 2 AU and 4 AU that are not accompanied by fast streams. The pressure waves are presumed to be generated by corotating streams near the Sun. For two of the three pressure waves that are discussed, the absence of a stream is probably a real, physical effect, viz., a consequence of deceleration of the stream by the associated compression wave. For the third pressure wave, the apparent absence of a stream may be a geometrical effect it is likely that the stream was at latitudes just above those of the spacecraft, while the associated shocks and compression wave extended over a broader range of latitudes so that they could be observed by the spacecraft. It is suggested that the development of large-scale non-linear pressure waves at the expense of the kinetic energy of streams produces a qualitative change in the solar wind in the outer heliosphere. Within a few AU the quasi-stationary solar wind structure is determined by corotating streams whose structure is determined by the boundary conditions near the Sun

  3. Wind fields of storms from surface isobars for wave hindcasting

    Digital Repository Service at National Institute of Oceanography (India)

    Varkey, M.J.; Vaithiyanathan, R.; Santanam, K.

    Marine operations of various types are critically linked to mean and extreme wave statistics. In the Indian seas extreme wave conditions are caused by cyclones and steady strong monsoon winds. Wave data from cyclone areas are not directly available...

  4. Flapping wing applied to wind generators

    Science.gov (United States)

    Colidiuc, Alexandra; Galetuse, Stelian; Suatean, Bogdan

    2012-11-01

    The new conditions at the international level for energy source distributions and the continuous increasing of energy consumption must lead to a new alternative resource with the condition of keeping the environment clean. This paper offers a new approach for a wind generator and is based on the theoretical aerodynamic model. This new model of wind generator helped me to test what influences would be if there will be a bird airfoil instead of a normal wind generator airfoil. The aim is to calculate the efficiency for the new model of wind generator. A representative direction for using the renewable energy is referred to the transformation of wind energy into electrical energy, with the help of wind turbines; the development of such systems lead to new solutions based on high efficiency, reduced costs and suitable to the implementation conditions.

  5. Seasonal Variability of Wind Sea and Swell Waves Climate along the Canary Current: The Local Wind Effect

    Directory of Open Access Journals (Sweden)

    Alvaro Semedo

    2018-03-01

    Full Text Available A climatology of wind sea and swell waves along the Canary eastern boundary current area, from west Iberia to Mauritania, is presented. The study is based on the European Centre for Medium-Range Weather Forecasts (ECMWF reanalysis ERA-Interim. The wind regime along the Canary Current, along west Iberia and north-west Africa, varies significantly from winter to summer. High summer wind speeds generate high wind sea waves, particularly along the coasts of Morocco and Western Sahara. Lower winter wind speeds, along with stronger extratropical storms crossing the North Atlantic sub-basin up north lead to a predominance of swell waves in the area during from December to February. In summer, the coast parallel wind interacts with the coastal headlands, increasing the wind speed and the locally generated waves. The spatial patterns of the wind sea or swell regional wave fields are shown to be different from the open ocean, due to coastal geometry, fetch dimensions, and island sheltering.

  6. Investigations of Wind/WAVES Dust Impacts

    Science.gov (United States)

    St Cyr, O. C.; Wilson, L. B., III; Rockcliffe, K.; Mills, A.; Nieves-Chinchilla, T.; Adrian, M. L.; Malaspina, D.

    2017-12-01

    The Wind spacecraft launched in November 1994 with a primary goal to observe and understand the interaction between the solar wind and Earth's magnetosphere. The waveform capture detector, TDS, of the radio and plasma wave investigation, WAVES [Bougeret et al., 1995], onboard Wind incidentally detected micron-sized dust as electric field pulses from the recollection of the impact plasma clouds (an unintended objective). TDS has detected over 100,000 dust impacts spanning almost two solar cycles; a dataset of these impacts has been created and was described in Malaspina & Wilson [2016]. The spacecraft continues to collect data about plasma, energetic particles, and interplanetary dust impacts. Here we report on two investigations recently conducted on the Wind/WAVES TDS database of dust impacts. One possible source of dust particles is the annually-recurring meteor showers. Using the nine major showers defined by the American Meteor Society, we compared dust count rates before, during, and after the peak of the showers using averaging windows of varying duration. However, we found no statistically significant change in the dust count rates due to major meteor showers. This appears to be an expected result since smaller grains, like the micron particles that Wind is sensitive to, are affected by electromagnetic interactions and Poynting-Robertson drag, and so are scattered away from their initial orbits. Larger grains tend to be more gravitationally dominated and stay on the initial trajectory of the parent body so that only the largest dust grains (those that create streaks as they burn up in the atmosphere) are left in the orbit of the parent body. Ragot and Kahler [2003] predicted that coronal mass ejections (CMEs) near the Sun could effectively scatter dust grains of comparable size to those observed by Wind. Thus, we examined the dust count rates immediately before, during, and after the passage of the 350 interplanetary CMEs observed by Wind over its 20+ year

  7. Pulsar magnetosphere-wind or wave

    International Nuclear Information System (INIS)

    Kennel, C.F.

    1979-01-01

    The structure of both the interior and exterior pulsar magnetosphere depends upon the strength of its plasma source near the surface of the star. We review wave models of exterior pulsar magnetospheres in the light of a vacuum pair-production source model proposed by Sturrock, and Ruderman and Sutherland. This model predicts the existence of a cutoff, determined by the neutron star's spin rate and magnetic field strenght, beyond which coherent radio emission is no longer possible. Since the observed distribution of pulsar spin periods and period derivatives, and the distribution of pulsars with missing radio pulses, is consistent with the pair production threshold, those neutron stars observed as radio pulsars can have relativistic magnetohydrodynamic wind exterior magnetospheres, and cannot have relativistic plasma wave exterior magnetospheres. On the other hand, most erstwhile pulsars in the galaxy are probably halo objects that emit weak fluxes of energetic photons that can have relativistic wave exterior magnetospheres. Extinct pulsars have not been yet observed

  8. Class Generation for Numerical Wind Atlases

    DEFF Research Database (Denmark)

    Cutler, N.J.; Jørgensen, B.H.; Ersbøll, Bjarne Kjær

    2006-01-01

    A new optimised clustering method is presented for generating wind classes for mesoscale modelling to produce numerical wind atlases. It is compared with the existing method of dividing the data in 12 to 16 sectors, 3 to 7 wind-speed bins and dividing again according to the stability...... of the atmosphere. Wind atlases are typically produced using many years of on-site wind observations at many locations. Numerical wind atlases are the result of mesoscale model integrations based on synoptic scale wind climates and can be produced in a number of hours of computation. 40 years of twice daily NCEP...... adapting to the local topography. The purpose of forming classes is to minimise the computational time for the mesoscale model while still representing the synoptic climate features. Only tried briefly in the past, clustering has traits that can be used to improve the existing class generation method...

  9. Simulation of wind wave growth with reference source functions

    Science.gov (United States)

    Badulin, Sergei I.; Zakharov, Vladimir E.; Pushkarev, Andrei N.

    2013-04-01

    conformity with theoretical predictions, previous simulations [2,6,9], experimental parameterizations of wave spectra [1,4] and to specify tunable parameters of terms (2,3). These simulations showed realistic spatio-temporal scales of wave evolution and spectral shaping close to conventional parameterizations [e.g. 4]. An additional important feature of the numerical solutions is a saturation of frequency-dependent wave steepness μw in short-frequency range. The work was supported by the Russian government contract No.11.934.31.0035, Russian Foundation for Basic Research grant 11-05-01114-a and ONR grant N00014-10-1-0991. References [1] S. I. Badulin, A. V. Babanin, D. Resio, and V. Zakharov. Weakly turbulent laws of wind-wave growth. J. Fluid Mech., 591:339-378, 2007. [2] S. I. Badulin, A. N. Pushkarev, D. Resio, and V. E. Zakharov. Self-similarity of wind-driven seas. Nonl. Proc. Geophys., 12:891-946, 2005. [3] S. I. Badulin and V. E. Zakharov. New dissipation function for weakly turbulent wind-driven seas. ArXiv e-prints, (1212.0963), December 2012. [4] M. A. Donelan, J. Hamilton, and W. H. Hui. Directional spectra of wind-generated waves. Phil. Trans. Roy. Soc. Lond. A, 315:509-562, 1985. [5] M. A. Donelan and W. J. Pierson-jr. Radar scattering and equilibrium ranges in wind-generated waves with application to scatterometry. J. Geophys. Res., 92(C5):4971-5029, 1987. [6] E. Gagnaire-Renou, M. Benoit, and S. I. Badulin. On weakly turbulent scaling of wind sea in simulations of fetch-limited growth. J. Fluid Mech., 669:178-213, 2011. [7] R. L. Snyder, F. W. Dobson, J. A. Elliot, and R. B. Long. Array measurements of atmospheric pressure fluctuations above surface gravity waves. J. Fluid Mech., 102:1-59, 1981. [8] D. J. Webb. Non-linear transfers between sea waves. Deep Sea Res., 25:279-298, 1978. [9] V. E. Zakharov, D. Resio, and A. N. Pushkarev. New wind input term consistent with experimental, theoretical and numerical considerations. ArXiv e-prints, (1212

  10. Optimal Control of Wind Power Generation

    Directory of Open Access Journals (Sweden)

    Pawel Pijarski

    2018-03-01

    Full Text Available Power system control is a complex task, which is strongly related to the number and kind of generating units as well as to the applied technologies, such as conventional coal fired power plants or wind and photovoltaic farms. Fast development of wind generation that is considered as unstable generation sets new strong requirements concerning remote control and data hubs cooperating with SCADA systems. Considering specific nature of the wind power generation, the authors analyze the problem of optimal control for wind power generation in farms located over a selected remote-controlled part of the Operator grid under advantageous wind conditions. This article presents an original stepwise method for tracing power flows that makes possible to eliminate current (power overloading of power grid branches. Its core idea is to consider the discussed problem as an optimization task.

  11. Directly driven generators for wind power applications

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-12-31

    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)

  12. 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)

  13. A high-resolution assessment of wind and wave energy potentials in the Red Sea

    KAUST Repository

    Langodan, Sabique; Viswanadhapalli, Yesubabu; Dasari, Hari Prasad; Knio, Omar; Hoteit, Ibrahim

    2016-01-01

    This study presents an assessment of the potential for harvesting wind and wave energy from the Red Sea based on an 18-year high-resolution regional atmospheric reanalysis recently generated using the Advanced Weather Research Forecasting model

  14. Wind turbines - generating noise or electricity?

    International Nuclear Information System (INIS)

    Russell, Eric

    1999-01-01

    Wind turbine technology has made great strides in the past few years. Annual energy output is up by two orders of magnitude and nacelle weight and noise has been halved. Computational fluid dynamics has paid a part in advancing knowledge of air flow and turbulence around wind generators. Current research is focused on how to increase turbine size and improve efficiency. A problem is that while larger wind turbines will produce cheaper electricity, the noise problem will mean that the number of acceptable sites will decrease. The biggest wind generators will need about 800 m clearance from the nearest house. (UK)

  15. Wavelet Transform Based Higher Order Statistical Analysis of Wind and Wave Time Histories

    Science.gov (United States)

    Habib Huseni, Gulamhusenwala; Balaji, Ramakrishnan

    2017-10-01

    Wind, blowing on the surface of the ocean, imparts the energy to generate the waves. Understanding the wind-wave interactions is essential for an oceanographer. This study involves higher order spectral analyses of wind speeds and significant wave height time histories, extracted from European Centre for Medium-Range Weather Forecast database at an offshore location off Mumbai coast, through continuous wavelet transform. The time histories were divided by the seasons; pre-monsoon, monsoon, post-monsoon and winter and the analysis were carried out to the individual data sets, to assess the effect of various seasons on the wind-wave interactions. The analysis revealed that the frequency coupling of wind speeds and wave heights of various seasons. The details of data, analysing technique and results are presented in this paper.

  16. Sensitivity of a numerical wave model on wind re-analysis datasets

    Science.gov (United States)

    Lavidas, George; Venugopal, Vengatesan; Friedrich, Daniel

    2017-03-01

    Wind is the dominant process for wave generation. Detailed evaluation of metocean conditions strengthens our understanding of issues concerning potential offshore applications. However, the scarcity of buoys and high cost of monitoring systems pose a barrier to properly defining offshore conditions. Through use of numerical wave models, metocean conditions can be hindcasted and forecasted providing reliable characterisations. This study reports the sensitivity of wind inputs on a numerical wave model for the Scottish region. Two re-analysis wind datasets with different spatio-temporal characteristics are used, the ERA-Interim Re-Analysis and the CFSR-NCEP Re-Analysis dataset. Different wind products alter results, affecting the accuracy obtained. The scope of this study is to assess different available wind databases and provide information concerning the most appropriate wind dataset for the specific region, based on temporal, spatial and geographic terms for wave modelling and offshore applications. Both wind input datasets delivered results from the numerical wave model with good correlation. Wave results by the 1-h dataset have higher peaks and lower biases, in expense of a high scatter index. On the other hand, the 6-h dataset has lower scatter but higher biases. The study shows how wind dataset affects the numerical wave modelling performance, and that depending on location and study needs, different wind inputs should be considered.

  17. Optimized power generation in offshore wind parks

    NARCIS (Netherlands)

    Oliveira Filho, J. de; Papp, Z.

    2011-01-01

    Electricity generation on offshore wind parks has an increasing economic importance - the European Commission foresees that 12% of the wind energy will be produced on offshore installations by 2020, and this share is likely to increase further in the following years. However, the continuously

  18. High-Altitude Wind Power Generation

    NARCIS (Netherlands)

    Fagiano, L.; Milanese, M.; Piga, D.

    2010-01-01

    Abstract—The paper presents the innovative technology of highaltitude wind power generation, indicated as Kitenergy, which exploits the automatic flight of tethered airfoils (e.g., power kites) to extract energy from wind blowing between 200 and 800 m above the ground. The key points of this

  19. Characteristics of bubble plumes, bubble-plume bubbles and waves from wind-steepened wave breaking

    NARCIS (Netherlands)

    Leifer, I.; Caulliez, G.; Leeuw, G. de

    2007-01-01

    Observations of breaking waves, associated bubble plumes and bubble-plume size distributions were used to explore the coupled evolution of wave-breaking, wave properties and bubble-plume characteristics. Experiments were made in a large, freshwater, wind-wave channel with mechanical wind-steepened

  20. Sporadic wind wave horse-shoe patterns

    Directory of Open Access Journals (Sweden)

    S. Yu. Annenkov

    1999-01-01

    Full Text Available The work considers three-dimensional crescent-shaped patterns often seen on water surface in natural basins and observed in wave tank experiments. The most common of these 'horse-shoe-like' patterns appear to be sporadic, i.e., emerging and disappearing spontaneously even under steady wind conditions. The paper suggests a qualitative model of these structures aimed at explaining their sporadic nature, physical mechanisms of their selection and their specific asymmetric form. First, the phenomenon of sporadic horse-shoe patterns is studied numerically using the novel algorithm of water waves simulation recently developed by the authors (Annenkov and Shrira, 1999. The simulations show that a steep gravity wave embedded into widespectrum primordial noise and subjected to small nonconservative effects typically follows the simple evolution scenario: most of the time the system can be considered as consisting of a basic wave and a single pair of oblique satellites, although the choice of this pair tends to be different at different instants. Despite the effective low-dimensionality of the multimodal system dynamics at relatively sho ' rt time spans, the role of small satellites is important: in particular, they enlarge the maxima of the developed satellites. The presence of Benjamin-Feir satellites appears to be of no qualitative importance at the timescales under consideration. The selection mechanism has been linked to the quartic resonant interactions among the oblique satellites lying in the domain of five-wave (McLean's class II instability of the basic wave: the satellites tend to push each other out of the resonance zone due to the frequency shifts caused by the quartic interactions. Since the instability domain is narrow (of order of cube of the basic wave steepness, eventually in a generic situation only a single pair survives and attains considerable amplitude. The specific front asymmetry is found to result from the interplay of quartic

  1. Integration of wind generation forecasts. Volume 2

    International Nuclear Information System (INIS)

    Ahlstrom, M.; Zavadil, B.; Jones, L.

    2005-01-01

    WindLogics is a company that specializes in atmospheric modelling, visualization and fine-scale forecasting systems for the wind power industry. A background of the organization was presented. The complexities of wind modelling were discussed. Issues concerning location and terrain, shear, diurnal and interannual variability were reviewed. It was suggested that wind power producers should aim to be mainstream, and that variability should be considered as intrinsic to fuel supply. Various utility operating impacts were outlined. Details of an Xcel NSP wind integration study were presented, as well as a studies conducted in New York state and Colorado. It was concluded that regulations and load following impacts with wind energy integration are modest. Overall impacts are dominated by costs incurred to accommodate wind generation variability and uncertainty in the day-ahead time frame. Cost impacts can be reduced with adjustments to operating strategies, improvements in wind forecasting and access to real-time markets. Details of WindLogic's wind energy forecast system were presented, as well as examples of day ahead and hour ahead forecasts and wind speed and power forecasts. Screenshots of control room integration, EMS integration and simulations were presented. Details of a utility-scale wind energy forecasting system funded by Xcel Renewable Development Fund (RDF) were also presented. The goal of the system was to optimize the way that wind forecast information is integrated into the control room environment. Project components were outlined. It was concluded that accurate day-ahead forecasting can lead to significant asset optimization. It was recommended that wind plants share data, and aim to resolve issues concerning grid codes and instrumentation. refs., tabs., figs

  2. Integrated Control for Small Power Wind Generator

    Directory of Open Access Journals (Sweden)

    Hongliang Liu

    2018-05-01

    Full Text Available The control strategies of the small power wind generator are usually divided into the maximum power point tracking (MPPT case, which requires the wind generator produce power as much as possible, and the power limited control (PLC case that demands the wind generator produce a power level following the load requirement. Integration of these two operating cases responding to flexible and sophisticated power demands is the main topic of this article. A small power wind generator including the sluggish mechanical dynamic phenomenon, which uses the permanent magnet synchronous generator, is introduced to validate different control methods integrating MPPT and PLC cases and based on hysteresis control. It is a matter of an indirect power control method derived from three direct methods following perturb and observe principle as well as from a look-up table. To analyze and compare the proposed power control methods, which are implemented into an emulator of a small power wind generator, a power demand profile is used. This profile is randomly generated based on measured rapid wind velocity data. Analyzing experimental results, from the power viewpoint, all proposed methods reveal steady-state error with big amount of peak resulting from the nature of perturb and observe.

  3. Development of wind power generation in China

    International Nuclear Information System (INIS)

    Zhiquan, Y.; Yan, C.; Lijun, X.

    1995-01-01

    Present status and development of wind power generation in China is described in this paper. China is vast in territory with abundant wind resources. The exploitable wind energy in China is estimated up to 253,000 MW. At present, more than 150 thousand small WTGs of a total capacity of 17 MW are used to provide residential electricity uses in non-grid connected areas and 13 wind farms, with above 160 medium and large scale grid connected WTGs (50-500 kW) of a total capacity of 30 MW, have been constructed. At the same time, some progress has been made in the fields of nation-wide wind resource assessment, measurement technology of wind turbine performance, the assimilation of foreign wind turbine technology, grid connected WTG technology and the operation of wind farm etc. It is planned that the total installed capacity of WTGs will reach 1000 MW by the end of 2000. Wind power generation could be a part of electric power industry in China. (Author)

  4. Wind-waves interactions in the Gulf of Eilat

    Science.gov (United States)

    Shani-Zerbib, Almog; Liberzon, Dan; T-SAIL Team

    2017-11-01

    The Gulf of Eilat, at the southern tip of Israel, with its elongated rectangular shape and unique diurnal wind pattern is an appealing location for wind-waves interactions research. Results of experimental work will be reported analyzing a continuous, 50 hour long, data. Using a combined array of wind and waves sensing instruments, the wave field statistics and its response to variations of wind forcing were investigated. Correlations between diurnal fluctuations in wind magnitude and direction and the wave field response will be discussed. The directional spread of waves' energy, as estimated by the Wavelet Directional Method, showed a strong response to small variations in wind flow direction attributed to the unique topography of the gulf surroundings and its bathymetry. Influenced by relatively strong winds during the light hours, the wave field was dominated by a significant amount of breakings that are well pronounced in the saturation range of waves spectra. Temporal growth and decay behavior of the waves during the morning and evening wind transition periods was examined. Sea state induced roughness, as experienced by the wind flow turbulent boundary layer, is examined in view of the critical layer theory. Israel Science Foundation Grant # 1521/15.

  5. Wind energy generation and pollution control

    International Nuclear Information System (INIS)

    Mohibullah; Mohd Nishat Anwar

    2009-01-01

    Full text: In India, power generation from wind has emerged as one of the most successful programme. It is making meaningful contributions to the overall power requirements in some of the states. India is emerging as fifth nation in wind power generation. As per the projections made by Ministry of New and Renewable Energy, Govt. of India, 10 % of the total capacity of power generation will come from renewable energy sources by the year 2012. It is envisaged that 50 % of this capacity may come from wind power alone. The paper describes a WECS (Wind Energy Conversion Systems) structure implemented in the MATLAB-Simulink simulation environment by using the specialized PSB toolbox, designed for modeling and simulation of electrical equipment. A study is made to show effectiveness in pollution control. An analytical study is also made regarding the potential of wind energy in limiting the amount of green house gases added into the atmosphere per year in different states in India. The amount of green house gases which are saved in the process are calculated for nine wind potential sites in India. The amount of green house gases saved is considerable to reduce environmental pollution and saving in carbon credit. Approximately an amount of 70681 Euro per year may be saved if the scheme is implemented and use of wind energy known in India is fully utilized for power generation. (author)

  6. Wave and offshore wind potential for the island of Tenerife

    International Nuclear Information System (INIS)

    Veigas, M.; Iglesias, G.

    2013-01-01

    Highlights: • The island aims to reduce its carbon footprint by developing renewable energy. • The substantial wave and offshore wind resources around the island are examined. • One area is appropriate for installing a hybrid wave–offshore wind farm. - Abstract: The island of Tenerife, a UNESCO Biosphere Reserve in the Atlantic Ocean, aims to be energy self-sufficient in order to reduce its carbon footprint. To accomplish this goal it should develop the renewable sources, in particular wave and offshore wind energy. The objectives of this work are twofold; (i) to characterize the wave and offshore wind power distribution around the island and (ii) to determine which offshore area is best suited for their exploitation, taking into account the resource and other conditioning factors such as the bathymetry, distance to the coastline and ports, and offshore zoning. To carry out this research, hindcast wave and wind data obtained with numerical models are used alongside observations from meteorological stations. One area, in the vicinity of Puerto de la Cruz, is identified as having great potential for installing a hybrid floating wave–wind farm. Both resources are characterized for the area selected: the wave resource in terms of wave directions, significant wave heights and energy periods; the offshore wind resource in terms of directions and speeds in addition to the seasonality for the both resources. It is found that most of the wave resource is provided by N and NNW waves with significant wave heights between 1.5 m and 3.0 m and energy periods between 10 s and 14 s. It follows that the Wave Energy Converters deployed in the area should have maximum efficiency in those ranges. As for the offshore wind resource, most of the energy corresponds to NNE and NE winds with speeds between 9 and 14 m s −1 , which should be taken into account when selecting the offshore wind turbines

  7. Wind power plant for electricity generation

    Energy Technology Data Exchange (ETDEWEB)

    Landsiedel, E

    1978-11-09

    The invention concerns a wind power plant which rotates on a vertical axis and is suitable for the generation of electricity. This wind power machine with a vertical axis can be mounted at any height, so that it can catch the wind on the vertical axis of rotation. Further, it does not have to be turned into the direction of the wind and fixed. The purpose of the invention is to obtain equal load on the structure due to the vertical axis. The purpose of the invention is fulfilled by having the wind vanes fixed above one another from the bottom to the top in 6 different directions. The particular advantage of the invention lies in the fact that the auxiliary blades can bring the other blades to the operating position in good time, due to their particular method of fixing.

  8. Transmission of wave energy through an offshore wind turbine farm

    DEFF Research Database (Denmark)

    Christensen, Erik Damgaard; Johnson, Martin; Sørensen, Ole Rene

    2013-01-01

    condition at infinity. From airborne and Satellite SAR (Synthetic Aperture Radar) a model has been derived for the change of the water surface friction C) inside and on the lee side of the offshore wind farm. The effects have been implemented in a spectral wind wave model,MIKE21 SW, and a parametric study......The transmission of wave energy passing an offshore wind farm is studied. Three effects that can change the wave field are analysed, which is the A) energy dissipation due to drag resistance, B) wave reflection/diffraction from structures, and C) the effect of a modified wind field inside...... and on the lee side of the wind farm. The drag dissipation, A), is quantified by a quadratic resistance law. The effect of B) is parameterised based on 1st order potential theory. A method to find the amount of reflected and transmitted wave energy is developed based on the panel method WAMIT™ and a radiation...

  9. Trends in Wind Turbine Generator Systems

    DEFF Research Database (Denmark)

    Polinder, Henk; Ferreira, Jan Abraham; Jensen, Bogi Bech

    2013-01-01

    This paper reviews the trends in wind turbine generator systems. After discussing some important requirements and basic relations, it describes the currently used systems: the constant speed system with squirrel-cage induction generator, and the three variable speed systems with doubly fed...... induction generator (DFIG), with gearbox and fully rated converter, and direct drive (DD). Then, possible future generator systems are reviewed. Hydraulic transmissions are significantly lighter than gearboxes and enable continuously variable transmission, but their efficiency is lower. A brushless DFIG...

  10. Asymmetry of wind waves studied in a laboratory tank

    Directory of Open Access Journals (Sweden)

    I. A. Leykin

    1995-01-01

    Full Text Available Asymmetry of wind waves was studied in laboratory tank tinder varied wind and fetch conditions using both bispectral analysis of wave records and third-order statistics of the surface elevation. It is found skewness S (the normalized third-order moment of surface elevation describing the horizontal asymmetry waves varies only slightly with the inverse wave u*/Cm (where u* is the air friction velocity and Cm is phase speed of the dominant waves. At the same time asymmetry A, which is determined from the Hilbert transform of the wave record and characterizes the skewness of the rate of change of surface elevation, increase consistently in magnitude with the ratio u*/Cm. This suggests that nonlinear distortion of the wave profile determined by the degree of wind forcing and is a sensitive indicator of wind-wave interaction processes. It is shown that the asymmetric profile of waves can described within the frameworks of the nonlinear nonspectral concept (Plate, 1972; Lake and Yuen, 197 according to which the wind-wave field can be represented as a coherent bound-wave system consisting mainly of dominant component w. and its harmonics propagating with the same speed C. , as observed by Ramamonjiaris and Coantic (1976. The phase shift between o. harmonics is found and shown to increase with the asymmetry of the waves.

  11. Asymmetry of wind waves studied in a laboratory tank

    Science.gov (United States)

    Ileykin, L. A.; Donelan, M. A.; Mellen, R. H.; McLaughlin, D. J.

    1995-03-01

    Asymmetry of wind waves was studied in laboratory tank tinder varied wind and fetch conditions using both bispectral analysis of wave records and third-order statistics of the surface elevation. It is found skewness S (the normalized third-order moment of surface elevation describing the horizontal asymmetry waves) varies only slightly with the inverse wave u*/Cm (where u* is the air friction velocity and Cm is phase speed of the dominant waves). At the same time asymmetry A, which is determined from the Hilbert transform of the wave record and characterizes the skewness of the rate of change of surface elevation, increase consistently in magnitude with the ratio u*/Cm. This suggests that nonlinear distortion of the wave profile determined by the degree of wind forcing and is a sensitive indicator of wind-wave interaction processes. It is shown that the asymmetric profile of waves can described within the frameworks of the nonlinear nonspectral concept (Plate, 1972; Lake and Yuen, 197 according to which the wind-wave field can be represented as a coherent bound-wave system consisting mainly of dominant component w. and its harmonics propagating with the same speed C. , as observed by Ramamonjiaris and Coantic (1976). The phase shift between o). harmonics is found and shown to increase with the asymmetry of the waves.

  12. Impact of the interfaces for wind and wave modeling - interpretation using COAWST, SAR and point measurements

    DEFF Research Database (Denmark)

    Air and sea interacts, where winds generate waves and waves affect the winds. This topic is ever relevant for offshore functions such as shipping, portal routines, wind farm operation and maintenance. In a coupled modeling system, the atmospheric modeling and the wave modeling interfere with each...... use the stress directly, thus avoiding the uncertainties caused by parameterizations. This study examines the efficiency of the wave impact transfer to the atmospheric modeling through the two types of interfaces, roughness length and stress, through the coupled......-ocean-atmosphere-wave-sediment-transport (COAWST) modeling system. The roughness length has been calculated using seven schemes (Charnock, Fan, Oost, Drennen, Liu, Andreas, Taylor-Yelland). The stress approach is applied through a wave boundary layer model in SWAN. The experiments are done to a case where the Synthetic Aperture Radar (SAR) image...

  13. Wind Integration into Various Generation Mixtures

    NARCIS (Netherlands)

    Maddaloni, J.D.; Rowe, A.M.; Kooten, van G.C.

    2009-01-01

    A load balance model is used to quantify the economic and environmental effects of integrating wind power into three typical generation mixtures. System operating costs over a specified period are minimized by controlling the operating schedule of the existing power generating facilities for a range

  14. Grid code requirements for wind power generation

    International Nuclear Information System (INIS)

    Djagarov, N.; Filchev, S.; Grozdev, Z.; Bonev, M.

    2011-01-01

    In this paper production data of wind power in Europe and Bulgaria and plans for their development within 2030 are reviewed. The main characteristics of wind generators used in Bulgaria are listed. A review of the grid code in different European countries, which regulate the requirements for renewable sources, is made. European recommendations for requirements harmonization are analyzed. Suggestions for the Bulgarian gird code are made

  15. Real time wave forecasting using wind time history and numerical model

    Science.gov (United States)

    Jain, Pooja; Deo, M. C.; Latha, G.; Rajendran, V.

    Operational activities in the ocean like planning for structural repairs or fishing expeditions require real time prediction of waves over typical time duration of say a few hours. Such predictions can be made by using a numerical model or a time series model employing continuously recorded waves. This paper presents another option to do so and it is based on a different time series approach in which the input is in the form of preceding wind speed and wind direction observations. This would be useful for those stations where the costly wave buoys are not deployed and instead only meteorological buoys measuring wind are moored. The technique employs alternative artificial intelligence approaches of an artificial neural network (ANN), genetic programming (GP) and model tree (MT) to carry out the time series modeling of wind to obtain waves. Wind observations at four offshore sites along the east coast of India were used. For calibration purpose the wave data was generated using a numerical model. The predicted waves obtained using the proposed time series models when compared with the numerically generated waves showed good resemblance in terms of the selected error criteria. Large differences across the chosen techniques of ANN, GP, MT were not noticed. Wave hindcasting at the same time step and the predictions over shorter lead times were better than the predictions over longer lead times. The proposed method is a cost effective and convenient option when a site-specific information is desired.

  16. Sensitivity of Gravity Wave Fluxes to Interannual Variations in Tropical Convection and Zonal Wind.

    Science.gov (United States)

    Alexander, M Joan; Ortland, David A; Grimsdell, Alison W; Kim, Ji-Eun

    2017-09-01

    Using an idealized model framework with high-frequency tropical latent heating variability derived from global satellite observations of precipitation and clouds, the authors examine the properties and effects of gravity waves in the lower stratosphere, contrasting conditions in an El Niño year and a La Niña year. The model generates a broad spectrum of tropical waves including planetary-scale waves through mesoscale gravity waves. The authors compare modeled monthly mean regional variations in wind and temperature with reanalyses and validate the modeled gravity waves using satellite- and balloon-based estimates of gravity wave momentum flux. Some interesting changes in the gravity spectrum of momentum flux are found in the model, which are discussed in terms of the interannual variations in clouds, precipitation, and large-scale winds. While regional variations in clouds, precipitation, and winds are dramatic, the mean gravity wave zonal momentum fluxes entering the stratosphere differ by only 11%. The modeled intermittency in gravity wave momentum flux is shown to be very realistic compared to observations, and the largest-amplitude waves are related to significant gravity wave drag forces in the lowermost stratosphere. This strong intermittency is generally absent or weak in climate models because of deficiencies in parameterizations of gravity wave intermittency. These results suggest a way forward to improve model representations of the lowermost stratospheric quasi-biennial oscillation winds and teleconnections.

  17. Assessment of wind characteristics for energy generation

    Energy Technology Data Exchange (ETDEWEB)

    Koray Ulgen [Ege University, Izmir (Turkey). Solar Energy Institute; Asir Genc [Selcuk University, Konya (Turkey). Dept. of Statistics; Arif Hepbasli [Ege University, Izmir (Turkey). Dept. of Mechanical Engineering; Galip Oturanc [Selcuk University, Konya (Turkey). Dept. of Mathematics

    2004-11-15

    Wind technology in Turkey has gained considerable maturity over the last five years, and wind energy projects are becoming commercially attractive in the country. In practice, it is essential to describe the variation of wind speeds for optimizing the design of the systems resulting in less energy generating costs. The wind variation for a typical site is usually described using the so-called Weibull distribution. In this study, the two Weibull parameters of the wind speed distribution function, the shape parameter k (dimensionless) and the scale parameter c (m/s), were computed from the wind speed data for Aksehir in Konya, located in Central Anatolia in Turkey (latitude: 38.35{sup o} and longitude: 31.42{sup o}). Wind data, consisting of hourly wind speed records over a 6 year period, 1997-2002, were obtained from the Aksehir State Meteorological Station. Based on the experimental data, it was found that the numerical values of both Weibull parameters (k and c) for Aksehir vary over a wide range. The yearly values of k range from 1.756 to 2.076, while those of c are in the range of 2.956 to 3.444. Average seasonal Weibull distributions for Aksehir are given. The wind speed distributions are represented by Weibull distribution and also by Rayleigh distribution with a special case of the Weibull distribution for k = 2. The Rayleigh distribution is found to be suitable to represent the actual probability of wind speed data for the site studied. (author)

  18. 1 MVA HTS-2G Generator for Wind Turbines

    Science.gov (United States)

    Kovalev, K. L.; Poltavets, V. N.; Ilyasov, R. I.; Verzhbitsky, L. G.; Kozub, S. S.

    2017-10-01

    The calculation, design simulations and design performance of 1 MVA HTS-2G (second-generation high-temperature superconductor) Generator for Wind Turbines were done in 2013-2014 [1]. The results of manufacturing and testing of 1 MVA generator are presented in the article. HTS-2G field coils for the rotor were redesigned, fabricated and tested. The tests have shown critical current of the coils, 41-45 A (self field within the ferromagnetic core, T = 77 K), which corresponds to the current of short samples at self field. Application of the copper inner frame on the pole has improved internal cooling conditions of HTS coil windings and reduced the magnetic field in the area, thereby increased the critical current value. The original construction of the rotor with a rotating cryostat was developed, which decreases the thermal in-flow to the rotor. The stator of 1 MW HTS-2G generator has been manufactured. In order to improve the specific weight of the generator, the wave (harmonic drive) multiplier was used, which provides increasing RPM from 15 RPM up to 600 RPM. The total mass of the multiplier and generator is significantly smaller compared to traditional direct-drive wind turbines generators [2-7]. Parameters of the multiplier and generator were chosen based on the actual parameters of wind turbines, namely: 15 RPM, power is 1 MVA. The final test of the assembled synchronous generator with HTS-2G field coils for Wind Turbines with output power 1 MVA was completed during 2015.

  19. Wind Profiles and Wave Spectra for Potential Wind Farms in South China Sea. Part II: Wave Spectrum Model

    Directory of Open Access Journals (Sweden)

    Yichao Liu

    2017-01-01

    Full Text Available Along with the commercialization of offshore wind energy in China, the South China Sea has been identified as ideal for constructing offshore wind farms, especially for farms consisting of floating wind turbines over deep waters. Since the wind profiles and wave spectra are somewhat primitive for the design of an offshore wind turbine, engineering models describing the wind and wave characteristics in the South China Sea area are necessary for the offshore wind energy exploitation given the meteorological, hydrological, and geographical differences between the South China Sea and the North/Norwegian Sea, where the commonly used wind profile and wave spectrum models were designated. In the present study; a series of numerical simulations were conducted to reveal the wave characteristics in the South China Sea under both typhoon and non-typhoon conditions. By analyzing the simulation results; the applicability of the Joint North Sea Wave Project (JONSWAP spectrum model; in terms of characterizing the wind-induced wave fields in the South China Sea; was discussed. In detail; the key parameters of the JONSWAP spectrum model; such as the Phillips constant; spectral width parameter; peak-enhancement factor, and high frequency tail decay; were investigated in the context of finding suitable values.

  20. Synchronous generator wind energy conversion control system

    Energy Technology Data Exchange (ETDEWEB)

    Medeiros, A.L.R. [Wind Energy Group, Recife (Brazil); Lima, A.M.N.; Jacobina, C.B.; Simoes, F.J. [DEE, Campina Grande (Brazil)

    1996-12-31

    This paper presents the performance evaluation and the design of the control system of a WECS (Wind Energy Conversion System) that employs a synchronous generator based on its digital simulation. The WECS discussed in this paper is connected to the utility grid through two Pulse Width Modulated (PWM) power converters. The structure of the proposed WECS enables us to achieve high performance energy conversion by: (i) maximizing the wind energy capture and (ii) minimizing the reactive power flowing between the grid and the synchronous generator. 8 refs., 19 figs.

  1. Characteristics of offshore extreme wind-waves detected by surface drifters with a low-cost GPS wave sensor

    Science.gov (United States)

    Komatsu, Kosei

    Wind-generated waves have been recognized as one of the most important factors of the sea surface roughness which plays crucial roles in various air-sea interactions such as energy, mo-mentum, heat and gas exchanges. At the same time, wind waves with extreme wave heights representatively called as freak or rogue waves have been a matter of great concern for many people involved in shipping, fishing, constracting, surfing and other marine activities, because such extreme waves frequently affect on the marine activities and sometimes cause serious dis-asters. Nevertheless, investigations of actual conditions for the evolution of wind waves in the offshore region are less and sparse in contrast to dense monitoring networks in the coastal re-gions because of difficulty of offshore observation with high accuracy. Recently accurate in situ observation of offshore wind waves is getting possible at low cost owing to a wave height and di-rection sensor developed by Harigae et al. (2004) by installing a point-positioning GPS receiver on a surface drifting buoy. The point-positioning GPS sensor can extract three dimensional movements of the buoy excited by ocean waves with minimizing effects of GPS point-positioning errors through the use of a high-pass filter. Two drifting buoys equipped with the GPS-based wave sensor charged by solar cells were drifted in the western North Pacific and one of them continued to observe wind waves during 16 months from Sep. 2007. The RMSE of the GPS-based wave sensor was less than 10cm in significant wave height and about 1s in significant wave period in comparison with other sensors, i.e. accelerometers installed on drifting buoys of Japan Meteorological Agency, ultrasonic sensors placed at the Hiratsuka observation station of the University of Tokyo and altimeter of the JASON-1. The GPS-based wave buoys enabled us to detect freak waves defined as waves whose height is more than twice the significant wave height. The observation conducted by

  2. Wind power, distrubted generation and transmission

    DEFF Research Database (Denmark)

    Østergaard, Poul Alberg

    the possibilities for integration of even more wind power using new power balancing strategies that exploit the possibilities given by the existence of CHP plants as well as the impact of heat pumps for district heating. The analyses demonstrate that it is possible to accommodate 50% or more wind power without......Denmark has the World?s highest penetration of wind power in electricity generation with a share of 15.0% of total domestic demand in 2002 (DEA, 2004). This is unevenly distributed in the two electricity systems of Denmark giving a share as high as 20.7% in Western Denmark in 2003 up from 18...... power balancing strategies are not applied, costly grid expansions will follow expansions in installed wind power capacity....

  3. Wind-wave modelling aspects within complicate topography

    Directory of Open Access Journals (Sweden)

    S. Christopoulos

    Full Text Available Wave forecasting aspects for basins with complicate geomorphology, such as the Aegean Sea, are investigated through an intercomparison study. The efficiency of the available wind models (ECMWF, UKMO to reproduce wind patterns over special basins, as well as three wave models incorporating different physics and characteristics (WAM, AUT, WACCAS, are tested for selected storm cases representing the typical wind situations over the basin. From the wave results, discussed in terms of time-series and statistical parameters, the crucial role is pointed out of the wind resolution and the reliability of the different wave models to estimate the wave climate in such a basin. The necessary grid resolution is also tested, while for a specific test case (December 1991 ERS-1 satellite data are compared with those of the model.

  4. Development of superconducting wind turbine generators

    DEFF Research Database (Denmark)

    Jensen, Bogi Bech; Mijatovic, Nenad; Abrahamsen, Asger Bech

    2013-01-01

    In this paper, the commercial activities in the field of superconducting machines, particularly superconducting wind turbine generators, are reviewed and presented. Superconducting generators have the potential to provide a compact and light weight drive train at high torques and slow rotational...... speeds, because high magnetic fields can be produced by coils with very little loss. Three different superconducting wind turbine generator topologies have been proposed by three different companies. One is based on low temperature superconductors; one is based on high temperature superconductors......; and one is a fully superconducting generator based on MgB2. It is concluded that there is large commercial interest in superconducting machines, with an increasing patenting activity. Such generators are, however, not without their challenges. The superconductors have to be cooled down to somewhere...

  5. Development of Superconducting Wind Turbine Generators

    DEFF Research Database (Denmark)

    Jensen, Bogi Bech; Mijatovic, Nenad; Abrahamsen, Asger Bech

    2012-01-01

    In this paper the commercial activities in the field of superconducting machines, particularly superconducting wind turbine generators, are reviewed and presented. Superconducting generators have the potential to provide a compact and light weight drive train at high torques and slow rotational...... speeds, because high magnetic fields can be produced by coils with very little loss. Three different superconducting wind turbine generator topologies have been proposed by three different companies. One is based on low temperature superconductors (LTS); one is based on high temperature superconductors...... (HTS); and one is a fully superconducting generator based on MgB2. It is concluded that there is large commercial interest in superconducting machines, with an increasing patenting activity. Such generators are however not without their challenges. The superconductors have to be cooled down...

  6. Extreme wind-wave modeling and analysis in the south Atlantic ocean

    Science.gov (United States)

    Campos, R. M.; Alves, J. H. G. M.; Guedes Soares, C.; Guimaraes, L. G.; Parente, C. E.

    2018-04-01

    A set of wave hindcasts is constructed using two different types of wind calibration, followed by an additional test retuning the input source term Sin in the wave model. The goal is to improve the simulation in extreme wave events in the South Atlantic Ocean without compromising average conditions. Wind fields are based on Climate Forecast System Reanalysis (CFSR/NCEP). The first wind calibration applies a simple linear regression model, with coefficients obtained from the comparison of CFSR against buoy data. The second is a method where deficiencies of the CFSR associated with severe sea state events are remedied, whereby "defective" winds are replaced with satellite data within cyclones. A total of six wind datasets forced WAVEWATCH-III and additional three tests with modified Sin in WAVEWATCH III lead to a total of nine wave hindcasts that are evaluated against satellite and buoy data for ambient and extreme conditions. The target variable considered is the significant wave height (Hs). The increase of sea-state severity shows a progressive increase of the hindcast underestimation which could be calculated as a function of percentiles. The wind calibration using a linear regression function shows similar results to the adjustments to Sin term (increase of βmax parameter) in WAVEWATCH-III - it effectively reduces the average bias of Hs but cannot avoid the increase of errors with percentiles. The use of blended scatterometer winds within cyclones could reduce the increasing wave hindcast errors mainly above the 93rd percentile and leads to a better representation of Hs at the peak of the storms. The combination of linear regression calibration of non-cyclonic winds with scatterometer winds within the cyclones generated a wave hindcast with small errors from calm to extreme conditions. This approach led to a reduction of the percentage error of Hs from 14% to less than 8% for extreme waves, while also improving the RMSE.

  7. Time-resolved PIV measurements of the atmospheric boundary layer over wind-driven surface waves

    Science.gov (United States)

    Markfort, Corey; Stegmeir, Matt

    2017-11-01

    Complex interactions at the air-water interface result in two-way coupling between wind-driven surface waves and the atmospheric boundary layer (ABL). Turbulence generated at the surface plays an important role in aquatic ecology and biogeochemistry, exchange of gases such as oxygen and carbon dioxide, and it is important for the transfer of energy and controlling evaporation. Energy transferred from the ABL promotes the generation and maintenance of waves. A fraction of the energy is transferred to the surface mixed layer through the generation of turbulence. Energy is also transferred back to the ABL by waves. There is a need to quantify the details of the coupled boundary layers of the air-water system to better understand how turbulence plays a role in the interactions. We employ time-resolved PIV to measure the detailed structure of the air and water boundary layers under varying wind and wave conditions in the newly developed IIHR Boundary-Layer Wind-Wave Tunnel. The facility combines a 30-m long recirculating water channel with an open-return boundary layer wind tunnel. A thick turbulent boundary layer is developed in the 1 m high air channel, over the water surface, allowing for the study of boundary layer turbulence interacting with a wind-driven wave field.

  8. Sound wave contours around wind turbine arrays

    International Nuclear Information System (INIS)

    Van Beek, A.; Van Blokland, G.J.

    1993-02-01

    Noise pollution is an important factor in selecting suitable sites for wind turbines in order to realize 1000 MW of wind power as planned by the Dutch government for the year 2000. Therefore an accurate assessment of wind turbine noise is important. The amount of noise pollution from a wind turbine depends on the wind conditions. An existing standard method to assess wind turbine noise is supplemented and adjusted. In the first part of the investigation the method was developed and applied for a solitary sound source. In the second part attention is paid to the use of the method for wind turbine arrays. It appears that the adjusted method results in a shift of the contours of the permitted noise level. In general the contours are 15-25% closer to the wind farm, which means that the minimal permitted distance between houses and wind turbine arrays can be reduced. 14 figs., 1 tab., 4 appendices, 7 refs

  9. Water waves generated by underwater explosion

    CERN Document Server

    Mehaute, Bernard Le

    1996-01-01

    This is the first book on explosion-generated water waves. It presents the theoretical foundations and experimental results of the generation and propagation of impulsively generated waves resulting from underwater explosions. Many of the theories and concepts presented herein are applicable to other types of water waves, in particular, tsunamis and waves generated by the fall of a meteorite. Linear and nonlinear theories, as well as experimental calibrations, are presented for cases of deep and shallow water explosions. Propagation of transient waves on dissipative, nonuniform bathymetries to

  10. Measurements of Waves in a Wind-wave Tank Under Steady and Time-varying Wind Forcing.

    Science.gov (United States)

    Zavadsky, Andrey; Shemer, Lev

    2018-02-13

    This manuscript describes an experimental procedure that allows obtaining diverse quantitative information on temporal and spatial evolution of water waves excited by time-dependent and steady wind forcing. Capacitance-type wave gauge and Laser Slope Gauge (LSG) are used to measure instantaneous water surface elevation and two components of the instantaneous surface slope at a number of locations along the test section of a wind-wave facility. The computer-controlled blower provides airflow over the water in the tank whose rate can vary in time. In the present experiments, the wind speed in the test section initially increases quickly from rest to the set value. It is then kept constant for the prescribed duration; finally, the airflow is shut down. At the beginning of each experimental run, the water surface is calm and there is no wind. Operation of the blower is initiated simultaneously with the acquisition of data provided by all sensors by a computer; data acquisition continues until the waves in the tank fully decay. Multiple independent runs performed under identical forcing conditions allow determining statistically reliable ensemble-averaged characteristic parameters that quantitatively describe wind-waves' variation in time for the initial development stage as a function of fetch. The procedure also allows characterizing the spatial evolution of the wave field under steady wind forcing, as well as decay of waves in time, once the wind is shut down, as a function of fetch.

  11. Testing the effectiveness of monolayers under wind and wave conditions.

    Science.gov (United States)

    Palada, C; Schouten, P; Lemckert, C

    2012-01-01

    Monolayers are highly desirable for their evaporation reducing capabilities due to their relatively minimal cost and ease of application. Despite these positive attributes, monolayers have consistently failed to perform effectively due to the harsh wind and wave conditions prevalent across real-world water reserves. An exhaustive and consistent study testing the influence of wind and wave combinations on monolayer performance has yet to be presented in the literature. To remedy this, the effect of simultaneous wind and wave conditions on a benchmark high-performance monolayer (octadecanol suspension, CH(3)(CH(2))(16)CH(2)OH) has been analysed. Subjected only to waves, the monolayer remained intact due to its innate ability to compress and expand. However, the constant simultaneous application of wind and waves caused the monolayer to break up and gather down-wind where it volatilised over time. At wind speeds above 1.3 m s(-1) the monolayer was completely ineffective. For wind speeds below this threshold, the monolayer had an influence on the evaporation rate dependent on wind speed. From these results a series of application protocols can now be developed for the optimised deployment of monolayers in real-world water reserves. This will be of interest to private, commercial and government organisations involved in the storage and management of water resources.

  12. Microprocessor control of a wind turbine generator

    Science.gov (United States)

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

    1978-01-01

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

  13. Spontaneous Wave Generation from Submesoscale Fronts and Filaments

    Science.gov (United States)

    Shakespeare, C. J.; Hogg, A.

    2016-02-01

    Submesoscale features such as eddies, fronts, jets and filaments can be significant sources of spontaneous wave generation at the ocean surface. Unlike near-inertial waves forced by winds, these spontaneous waves are typically of higher frequency and can propagate through the thermocline, whereupon they break and drive mixing in the ocean interior. Here we investigate the spontaneous generation, propagation and subsequent breaking of these waves using a combination of theory and submesoscale resolving numerical models. The mechanism of generation is nearly identical to that of lee waves where flow is deflected over a rigid obstacle on the sea floor. Here, very sharp fronts and filaments of order 100m width moving in the submesoscale surface flow generate "surface lee waves" by presenting an obstacle to the surrounding stratified fluid. Using our numerical model we quantify the net downward wave energy flux from the surface, and where it is dissipated in the water column. Our results suggest an alternative to the classical paradigm where the energy associated with mixing in the ocean interior is sourced from bottom-generated lee waves.

  14. Site-optimization of wind turbine generators

    Energy Technology Data Exchange (ETDEWEB)

    Wolff, T.J. de; Thillerup, J. [Nordtank Energy Group, Richmond, VA (United States)

    1997-12-31

    The Danish Company Nordtank is one of the pioneers within the wind turbine industry. Since 1981 Nordtank has installed worldwide more than 2500 wind turbine generators with a total name plate capacity that is exceeding 450 MW. The opening up of new and widely divergent markets has demanded an extremely flexible approach towards wind turbine construction. The Nordtank product range has expanded considerable in recent years, with the main objective to develop wind energy conversion machines that can run profitable in any given case. This paper will describe site optimization of Nordtank wind turbines. Nordtank has developed a flexible design concept for its WTGs in the 500/750 kW range, in order to offer the optimal WTG solution for any given site and wind regime. Through this flexible design, the 500/750 turbine line can adjust the rotor diameter, tower height and many other components to optimally fit the turbine to each specific project. This design philosophy will be illustrated with some case histories of recently completed projects.

  15. Quantifying the Benefits of Combining Offshore Wind and Wave Energy

    Science.gov (United States)

    Stoutenburg, E.; Jacobson, M. Z.

    2009-12-01

    For many locations the offshore wind resource and the wave energy resource are collocated, which suggests a natural synergy if both technologies are combined into one offshore marine renewable energy plant. Initial meteorological assessments of the western coast of the United States suggest only a weak correlation in power levels of wind and wave energy at any given hour associated with the large ocean basin wave dynamics and storm systems of the North Pacific. This finding indicates that combining the two power sources could reduce the variability in electric power output from a combined wind and wave offshore plant. A combined plant is modeled with offshore wind turbines and Pelamis wave energy converters with wind and wave data from meteorological buoys operated by the US National Buoy Data Center off the coast of California, Oregon, and Washington. This study will present results of quantifying the benefits of combining wind and wave energy for the electrical power system to facilitate increased renewable energy penetration to support reductions in greenhouse gas emissions, and air and water pollution associated with conventional fossil fuel power plants.

  16. Simulation of Small Wind Turbine Generation System Using Ring Winding Slotless PMSG by FEM

    OpenAIRE

    徳永, 翔平; 袈裟丸, 勝己; Tokunaga, Shohei; Kesamaru, Katsumi

    2011-01-01

    This paper describes a novel small wind turbine generation system with ring winding slotless PMSG. To reduce cogging torque, ring winding PM generator is used for a wind turbine generator. Using finite element analysis, the characteristics of slotless PMSGs are elucidated and the dynamic performance of the proposed system with MPPT control is represented. In this paper, the constant wind test and the quasi-natural wind test are conducted. The results of these tests indicate the proposed syste...

  17. ULF Wave Activity in the Magnetosphere: Resolving Solar Wind Interdependencies to Identify Driving Mechanisms

    Science.gov (United States)

    Bentley, S. N.; Watt, C. E. J.; Owens, M. J.; Rae, I. J.

    2018-04-01

    Ultralow frequency (ULF) waves in the magnetosphere are involved in the energization and transport of radiation belt particles and are strongly driven by the external solar wind. However, the interdependency of solar wind parameters and the variety of solar wind-magnetosphere coupling processes make it difficult to distinguish the effect of individual processes and to predict magnetospheric wave power using solar wind properties. We examine 15 years of dayside ground-based measurements at a single representative frequency (2.5 mHz) and a single magnetic latitude (corresponding to L ˜ 6.6RE). We determine the relative contribution to ULF wave power from instantaneous nonderived solar wind parameters, accounting for their interdependencies. The most influential parameters for ground-based ULF wave power are solar wind speed vsw, southward interplanetary magnetic field component Bzstill account for significant amounts of power. We suggest that these three parameters correspond to driving by the Kelvin-Helmholtz instability, formation, and/or propagation of flux transfer events and density perturbations from solar wind structures sweeping past the Earth. We anticipate that this new parameter reduction will aid comparisons of ULF generation mechanisms between magnetospheric sectors and will enable more sophisticated empirical models predicting magnetospheric ULF power using external solar wind driving parameters.

  18. Plan for the Brent Spar. Wind and wave energy converter

    International Nuclear Information System (INIS)

    De Vries, E.

    1996-01-01

    In a competition on the future of the much discussed oil platform Brent Spar of Shell the idea to retrofit the platform into a combined wind/wave energy converter appears to be an attractive option for Shell

  19. Plasma wave and second harmonic generation

    International Nuclear Information System (INIS)

    Sodha, M.S.; Sharma, J.K.; Tewari, D.P.; Sharma, R.P.; Kaushik, S.C.

    1978-01-01

    An investigation is made of a plasma wave at pump wave frequency and second harmonic generation caused by a self induced transverse inhomogeneity introduced by a Gaussian electromagnetic beam in a hot collisionless plasma. In the presence of a Gaussian beam the carriers get redistributed from the high field region to the low field region by ponderomative force and a transverse density gradient is established in the plasma. When the electric vector of the main beam is parallel to this density gradient, a plasma wave at the pump wave frequency is generated. In addition to this the transverse intensity gradient of the electromagnetic wave also contributes significantly to the plasma wave generation. The power of the plasma wave exhibits a maximum and minimum with the power of the pump wave (at z = 0). The generated plasma wave interacts with the electromagnetic wave and leads to the generation of a second harmonic. Furthermore, if the initial power of the pump wave is more than the critical power for self-focusing, the beam gets self-focused and hence the generated plasma wave and second harmonic which depend upon the background electron concentration and power of the main beam also get accordingly modified. (author)

  20. Characterization of wind velocities in the upstream induction zone of a wind turbine using scanning continuous-wave lidars

    DEFF Research Database (Denmark)

    Simley, Eric; Angelou, Nikolas; Mikkelsen, Torben Krogh

    2016-01-01

    As a wind turbine generates power, induced velocities, lower than the freestream velocity, will be present upstream of the turbine due to perturbation of the flow by the rotor. In this study, the upstream induction zone of a 225kW horizontal axis Vestas V27 wind turbine located at the Danish...... Technical University’s Risø campus is investigated using a scanning Light Detection and Ranging (lidar) system. Three short-range continuous-waveWindScanner” lidars are positioned in the field around the V27 turbine allowing detection of all three components of the wind velocity vectors within...... the induction zone. The time-averaged mean wind speeds at different locations in the upstream induction zone are measured by scanning a horizontal plane at hub height and a vertical plane centered at the middle of the rotor extending roughly 1.5 rotor diameters (D) upstream of the rotor. Turbulence statistics...

  1. Evolution of offshore wind waves tracked by surface drifters with a point-positioning GPS sensor

    Science.gov (United States)

    Komatsu, K.

    2009-12-01

    Wind-generated waves have been recognized as one of the most important factors of the sea surface roughness which plays crucial roles in various air-sea interactions such as energy, momentum, heat and gas exchanges. At the same time, wind waves with extreme wave heights representatively called as freak or rogue waves have been a matter of great concern for many people involved in shipping, fishing, constracting, surfing and other marine activities, because such extreme waves frequently affect on the marine activities and sometimes cause serious disasters. Nevertheless, investigations of actual conditions for the evolution of wind waves in the offshore region are less and sparse in contrast to dense monitoring networks in the coastal regions because of difficulty of offshore observation with high accuracy. Recently accurate in situ observation of offshore wind waves is getting possible at low cost owing to a wave height and direction sensor developed by Harigae et al. (2004) by installing a point-positioning GPS receiver on a surface drifting buoy. The point-positioning GPS sensor can extract three dimensional movements of the buoy excited by ocean waves with minimizing effects of GPS point-positioning errors through the use of a high-pass filter. Two drifting buoys equipped with the GPS-based wave sensor charged by solar cells were drifted in the western North Pacific and one of them continued to observe wind waves during 16 months from Sep. 2007. The RMSE of the GPS-based wave sensor was less than 10cm in significant wave height and about 1s in significant wave period in comparison with other sensors, i.e. accelerometers installed on drifting buoys of Japan Meteorological Agency, ultrasonic sensors placed at the Hiratsuka observation station of the University of Tokyo and altimeter of the JASON-1. The GPS-based wave buoys enabled us to detect freak waves defined as waves whose height is more than twice the significant wave height. The observation conducted by the

  2. Experimental and numerical study of a 10MW TLP wind turbine in waves and wind

    DEFF Research Database (Denmark)

    Pegalajar Jurado, Antonio Manuel; Hansen, Anders Mandrup; Laugesen, Robert

    2016-01-01

    with the tests by matching key system features, namely the steady thrust curve and the decay tests in water. The calibrated model is used to reproduce the wind-wave climates in the laboratory, including regular and irregular waves, with and without wind. The model predictions are compared to the measured data......This paper presents tests on a 1:60 version of the DTU 10MW wind turbine mounted on a tension leg platform and their numerical reproduction. Both the experimental setup and the numerical model are Froude-scaled, and the dynamic response of the floating wind turbine to wind and waves is compared......, and a good agreement is found for surge and heave, while some discrepancies are observed for pitch, nacelle acceleration and line tension. The addition of wind generally improves the agreement with test results. The aerodynamic damping is identified in both tests and simulations. Finally, the sources...

  3. Wave run-up on offshore wind turbine foundations

    DEFF Research Database (Denmark)

    Baden, Elisabeth; Skourup, Jesper; Andersen, Thomas Lykke

    2012-01-01

    Wave run-up on appurtenances like boat landings, ladders, platforms and J-tubes of Offshore Wind Turbine foundations have in some cases caused severe and costly damage to these installations. A well-known example of large run-up was registered at the foundations of Horns Reef Offshore Wind Farm, ...

  4. Wind-Driven Waves in Tampa Bay, Florida

    Science.gov (United States)

    Gilbert, S. A.; Meyers, S. D.; Luther, M. E.

    2002-12-01

    Turbidity and nutrient flux due to sediment resuspension by waves and currents are important factors controlling water quality in Tampa Bay. During December 2001 and January 2002, four Sea Bird Electronics SeaGauge wave and tide recorders were deployed in Tampa Bay in each major bay segment. Since May 2002, a SeaGauge has been continuously deployed at a site in middle Tampa Bay as a component of the Bay Regional Atmospheric Chemistry Experiment (BRACE). Initial results for the summer 2002 data indicate that significant wave height is linearly dependent on wind speed and direction over a range of 1 to 12 m/s. The data were divided into four groups according to wind direction. Wave height dependence on wind speed was examined for each group. Both northeasterly and southwesterly winds force significant wave heights that are about 30% larger than those for northwesterly and southeasterly winds. This difference is explained by variations in fetch due to basin shape. Comparisons are made between these observations and the results of a SWAN-based model of Tampa Bay. The SWAN wave model is coupled to a three-dimensional circulation model and computes wave spectra at each model grid cell under observed wind conditions and modeled water velocity. When SWAN is run without dissipation, the model results are generally similar in wave period but about 25%-50% higher in significant wave height than the observations. The impact of various dissipation mechanisms such as bottom drag and whitecapping on the wave state is being investigated. Preliminary analyses on winter data give similar results.

  5. Influence of wave modelling on the prediction of fatigue for offshore wind turbines

    Science.gov (United States)

    Veldkamp, H. F.; van der Tempel, J.

    2005-01-01

    Currently it is standard practice to use Airy linear wave theory combined with Morison's formula for the calculation of fatigue loads for offshore wind turbines. However, offshore wind turbines are typically placed in relatively shallow water depths of 5-25 m where linear wave theory has limited accuracy and where ideally waves generated with the Navier-Stokes approach should be used. This article examines the differences in fatigue for some representative offshore wind turbines that are found if first-order, second-order and fully non-linear waves are used. The offshore wind turbines near Blyth are located in an area where non-linear wave effects are common. Measurements of these waves from the OWTES project are used to compare the different wave models with the real world in spectral form. Some attention is paid to whether the shape of a higher-order wave height spectrum (modified JONSWAP) corresponds to reality for other places in the North Sea, and which values for the drag and inertia coefficients should be used. Copyright

  6. Estimating Wind and Wave Induced Forces On a Floating Wind Turbine

    DEFF Research Database (Denmark)

    Henriksen, Lars Christian; Natarajan, Anand; Kim, Taeseong

    2013-01-01

    -principles derived state space model of the floating wind turbine. The ability to estimate aero- and hydrodynamic states could prove crucial for the performance of model-based control methods applied on floating wind turbines. Furthermore, two types of water kinematics have been compared two determine whether......In this work, the basic model for a spar buoy floating wind turbine [1], used by an extended Kalman filter, is presented and results concerning wind speed and wave force estimations are shown. The wind speed and aerodynamic forces are estimated using an extended Kalman filter based on a first...... or not linear and nonlinear water kinematics lead to significantly different loads....

  7. Operating of Small Wind Power Plants with Induction Generators

    OpenAIRE

    Jakub Nevrala; Stanislav Misak

    2008-01-01

    This paper describes different systems of small wind power plants with induction generators used in the Czech Republic. Problems of wind power plants running with induction generators are solved within partial target of the research project MSM 6198910007. For small wind power plants is used induction motor as a generator. Parameters of the name plate of motor must be resolved for generator running on measuring base. These generators are running as a separately working generators or generator...

  8. Generation and Analysis of Random Waves

    DEFF Research Database (Denmark)

    Liu, Zhou; Frigaard, Peter

    applied to hydrology, wind mechanics, ice mechanics, etc., not to mention the fact that spectral analysis comes originally from optics and electronics. The book intents to be a textbook for senior and graduate students who have interest in coastal and offshore structures. The only pre......Sea waves are the most important phenomenon to be considered in the design of coastal and offshore structures. It should be stressed that, even though all contents in the book are related to sea waves, they have a broader application in practice. For example, the extreme theory has also been......-requirement for the book is the knowledge of linear wave theory....

  9. Alfvén wave mixing and non-JWKB waves in stellar winds

    International Nuclear Information System (INIS)

    Webb, G M; McKenzie, J F; Hu, Q; Zank, G P

    2013-01-01

    Alfvén wave mixing equations used in locally incompressible turbulence transport equations in the solar wind contain as a special case, non-Jeffreys–Wentzel–Kramers–Brouillon (non-JWKB) wave equations used in models of Alfvén wave driven winds. We discuss the canonical wave energy equation; the physical wave energy equation, and the JWKB limit of the wave interaction equations. Lagrangian and Hamiltonian variational principles for the waves are developed. Noether’s theorem is used to derive the canonical wave energy equation which is associated with the linearity symmetry of the equations. A further conservation law associated with time translation invariance of the action, applicable for steady background wind flows is also derived. In the latter case, the conserved density is the Hamiltonian density for the waves, which is distinct from the canonical wave energy density. The canonical wave energy conservation law is a special case of a wider class of conservation laws associated with Green’s theorem for the wave mixing system and the adjoint wave mixing system, which are related to Noether’s second theorem. In the sub-Alfvénic flow, inside the Alfvén point of the wind, the backward and forward waves have positive canonical energy densities, but in the super-Alfvénic flow outside the Alfvén critical point, the backward Alfvén waves are negative canonical energy waves, and the forward Alfvén waves are positive canonical energy waves. Reflection and transmission coefficients for the backward and forward waves in both the sub-Alfvénic and super-Alfvénic regions of the flow are discussed. (paper)

  10. Electron wind in strong wave guide fields

    Science.gov (United States)

    Krienen, F.

    1985-03-01

    The X-ray activity observed near highly powered waveguide structures is usually caused by local electric discharges originating from discontinuities such as couplers, tuners or bends. In traveling waves electrons move in the direction of the power flow. Seed electrons can multipactor in a traveling wave, the moving charge pattern is different from the multipactor in a resonant structure and is self-extinguishing. The charge density in the wave guide will modify impedance and propagation constant of the wave guide. The radiation level inside the output wave guide of the SLAC, 50 MW, S-band, klystron is estimated. Possible contributions of radiation to window failure are discussed.

  11. Modulated Field Synchronous Generator for Wind Turbines

    Directory of Open Access Journals (Sweden)

    Petru Chioncel

    2013-01-01

    Full Text Available This paper presents a modern electromechanical conversion systemsolution as the modulated field synchronous generator, offering on theone hand, an output voltage with constant frequency in terms of speedvariation of the wind turbine and on the other hand an advantagepower / weight ratio due to the high frequency for which the magneticcircuit of the electric machine is sized. The mathematical model of the modulated field synchronous generator is implemented in MatLABmodeling language, highlighting the command structure on thetransistors bases of the inverter transistors, through which thefunctioning of the electric machine can be studied, especially in terms of the frequency of the delivered voltage.

  12. Wind Wave Behavior in Fetch and Depth Limited Estuaries

    Science.gov (United States)

    Karimpour, Arash; Chen, Qin; Twilley, Robert R.

    2017-01-01

    Wetland dominated estuaries serve as one of the most productive natural ecosystems through their ecological, economic and cultural services, such as nursery grounds for fisheries, nutrient sequestration, and ecotourism. The ongoing deterioration of wetland ecosystems in many shallow estuaries raises concerns about the contributing erosive processes and their roles in restraining coastal restoration efforts. Given the combination of wetlands and shallow bays as landscape components that determine the function of estuaries, successful restoration strategies require knowledge of wind wave behavior in fetch and depth limited water as a critical design feature. We experimentally evaluate physics of wind wave growth in fetch and depth limited estuaries. We demonstrate that wave growth rate in shallow estuaries is a function of wind fetch to water depth ratio, which helps to develop a new set of parametric wave growth equations. We find that the final stage of wave growth in shallow estuaries can be presented by a product of water depth and wave number, whereby their product approaches 1.363 as either depth or wave energy increases. Suggested wave growth equations and their asymptotic constraints establish the magnitude of wave forces acting on wetland erosion that must be included in ecosystem restoration design.

  13. A numerical study of the wave shoaling effect on wind-wave momentum flux

    Science.gov (United States)

    Hao, Xuanting; Shen, Lian

    2017-11-01

    Momentum transfer between wind and waves is crucial to many physical processes in air-sea interactions. For decades, there has been a number of observational evidence that the surface roughness in the nearshore region is notably higher than in the open sea. In order to explain the mechanism behind this important phenomenon, in particular the wave shoaling effect on surface roughness, we conduct a series of numerical experiments using the wind-wave module of WOW (Wave-Ocean-Wind), a high-fidelity computational framework developed in house. We use prescribed monochromatic waves with linear shoaling effect incorporated, while the wind field is simulated using wall-resolved large-eddy simulation. A comparison between a shallow water wave case and deep water wave cases shows remarkably stronger wave effects on the wind for the former. Detailed analyses show that the increased surface roughness is closely associated with the increased form drag that is mainly due to the reduced wave age in wave shoaling.

  14. A Dynamic Wind Generation Model for Power Systems Studies

    OpenAIRE

    Estanqueiro, Ana

    2007-01-01

    In this paper, a wind park dynamic model is presented together with a base methodology for its application to power system studies. This detailed wind generation model addresses the wind turbine components and phenomena more relevant to characterize the power quality of a grid connected wind park, as well as the wind park response to the grid fast perturbations, e.g., low voltage ride through fault. The developed model was applied to the operating conditions of the selected sets of wind turbi...

  15. Discussion on mass concrete construction of wind turbine generator foundation

    Science.gov (United States)

    Shang, Liang; Wu, Chaoxiang; Yin, Xiaoyong

    2018-04-01

    Wind power is one of the main power sources currently. China has rich wind power resources, wind power plants are developed faster and faster. However, China wind power construction started late, which is lack of relevant experience technology. It is easy to produce quality problems. The key to the construction quality of wind power plant is the construction quality of mass concrete construction. Therefore, construction technology and quality control of wind turbine generator foundation mass concrete are discussed and analyzed in the paper.

  16. Wind and wave dataset for Matara, Sri Lanka

    Science.gov (United States)

    Luo, Yao; Wang, Dongxiao; Priyadarshana Gamage, Tilak; Zhou, Fenghua; Madusanka Widanage, Charith; Liu, Taiwei

    2018-01-01

    We present a continuous in situ hydro-meteorology observational dataset from a set of instruments first deployed in December 2012 in the south of Sri Lanka, facing toward the north Indian Ocean. In these waters, simultaneous records of wind and wave data are sparse due to difficulties in deploying measurement instruments, although the area hosts one of the busiest shipping lanes in the world. This study describes the survey, deployment, and measurements of wind and waves, with the aim of offering future users of the dataset the most comprehensive and as much information as possible. This dataset advances our understanding of the nearshore hydrodynamic processes and wave climate, including sea waves and swells, in the north Indian Ocean. Moreover, it is a valuable resource for ocean model parameterization and validation. The archived dataset (Table 1) is examined in detail, including wave data at two locations with water depths of 20 and 10 m comprising synchronous time series of wind, ocean astronomical tide, air pressure, etc. In addition, we use these wave observations to evaluate the ERA-Interim reanalysis product. Based on Buoy 2 data, the swells are the main component of waves year-round, although monsoons can markedly alter the proportion between swell and wind sea. The dataset (Luo et al., 2017) is publicly available from Science Data Bank (https://doi.org/10.11922/sciencedb.447).

  17. Wind and wave dataset for Matara, Sri Lanka

    Directory of Open Access Journals (Sweden)

    Y. Luo

    2018-01-01

    Full Text Available We present a continuous in situ hydro-meteorology observational dataset from a set of instruments first deployed in December 2012 in the south of Sri Lanka, facing toward the north Indian Ocean. In these waters, simultaneous records of wind and wave data are sparse due to difficulties in deploying measurement instruments, although the area hosts one of the busiest shipping lanes in the world. This study describes the survey, deployment, and measurements of wind and waves, with the aim of offering future users of the dataset the most comprehensive and as much information as possible. This dataset advances our understanding of the nearshore hydrodynamic processes and wave climate, including sea waves and swells, in the north Indian Ocean. Moreover, it is a valuable resource for ocean model parameterization and validation. The archived dataset (Table 1 is examined in detail, including wave data at two locations with water depths of 20 and 10 m comprising synchronous time series of wind, ocean astronomical tide, air pressure, etc. In addition, we use these wave observations to evaluate the ERA-Interim reanalysis product. Based on Buoy 2 data, the swells are the main component of waves year-round, although monsoons can markedly alter the proportion between swell and wind sea. The dataset (Luo et al., 2017 is publicly available from Science Data Bank (https://doi.org/10.11922/sciencedb.447.

  18. Low frequency wave sources in the outer magnetosphere, magnetosheath, and near Earth solar wind

    Directory of Open Access Journals (Sweden)

    O. D. Constantinescu

    2007-11-01

    Full Text Available The interaction of the solar wind with the Earth magnetosphere generates a broad variety of plasma waves through different mechanisms. The four Cluster spacecraft allow one to determine the regions where these waves are generated and their propagation directions. One of the tools which takes full advantage of the multi-point capabilities of the Cluster mission is the wave telescope technique which provides the wave vector using a plane wave representation. In order to determine the distance to the wave sources, the source locator – a generalization of the wave telescope to spherical waves – has been recently developed. We are applying the source locator to magnetic field data from a typical traversal of Cluster from the cusp region and the outer magnetosphere into the magnetosheath and the near Earth solar wind. We find a high concentration of low frequency wave sources in the electron foreshock and in the cusp region. To a lower extent, low frequency wave sources are also found in other magnetospheric regions.

  19. A simplified approach to detect undervoltage tripping of wind generators

    Energy Technology Data Exchange (ETDEWEB)

    Sigrist, Lukas; Rouco, Luis [Universidad Pontificia Comillas, Madrid (Spain). Inst. de Investigacion Tecnologica

    2012-07-01

    This paper proposes a simplified but fast approach based on a Norton equivalent of wind generators to detect undervoltage tripping of wind generators. This approach is successfully applied to a real wind farm. The relevant grid code requires the wind farm to withstand a voltage dip of 0% retained voltage. The ability of the wind generators to raise the voltage supplying reactive current and to avoid undervoltage tripping is investigated. The obtained results are also compared with the results obtained from detailed dynamic simulations, which make use of wind generator models complying with the relevant grid code. (orig.)

  20. Aggregated wind power generation probabilistic forecasting based on particle filter

    International Nuclear Information System (INIS)

    Li, Pai; Guan, Xiaohong; Wu, Jiang

    2015-01-01

    Highlights: • A new method for probabilistic forecasting of aggregated wind power generation. • A dynamic system is established based on a numerical weather prediction model. • The new method handles the non-Gaussian and time-varying wind power uncertainties. • Particle filter is applied to forecast predictive densities of wind generation. - Abstract: Probability distribution of aggregated wind power generation in a region is one of important issues for power system daily operation. This paper presents a novel method to forecast the predictive densities of the aggregated wind power generation from several geographically distributed wind farms, considering the non-Gaussian and non-stationary characteristics in wind power uncertainties. Based on a mesoscale numerical weather prediction model, a dynamic system is established to formulate the relationship between the atmospheric and near-surface wind fields of geographically distributed wind farms. A recursively backtracking framework based on the particle filter is applied to estimate the atmospheric state with the near-surface wind power generation measurements, and to forecast the possible samples of the aggregated wind power generation. The predictive densities of the aggregated wind power generation are then estimated based on these predicted samples by a kernel density estimator. In case studies, the new method presented is tested on a 9 wind farms system in Midwestern United States. The testing results that the new method can provide competitive interval forecasts for the aggregated wind power generation with conventional statistical based models, which validates the effectiveness of the new method

  1. Methods and apparatus for cooling wind turbine generators

    Science.gov (United States)

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

    2008-10-28

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

  2. The environmental interactions of tidal and wave energy generation devices

    OpenAIRE

    Frid, C.; Andonegi, E.; Depestele, J.; Judd, A.; Rihan, D.; Rogers, S.I.; Kenchington, E.

    2012-01-01

    Global energy demand continues to grow and tidal and wave energy generation devices can provide a significant source of renewable energy. Technological developments in offshore engineering and the rising cost of traditional energy means that offshore energy resources will be economic in the next few years. While there is now a growing body of data on the ecological impacts of offshore wind farms, the scientific basis on which to make informed decisions about the environmental effects of other...

  3. Beating HF waves to generate VLF waves in the ionosphere

    Science.gov (United States)

    Kuo, Spencer; Snyder, Arnold; Kossey, Paul; Chang, Chia-Lie; Labenski, John

    2012-03-01

    Beat-wave generation of very low frequency (VLF) waves by two HF heaters in the ionosphere is formulated theoretically and demonstrated experimentally. The heater-induced differential thermal pressure force and ponderomotive force, which dominate separately in the D and F regions of the ionosphere, drive an electron current for the VLF emission. A comparison, applying appropriate ionospheric parameters shows that the ponderomotive force dominates in beat-wave generation of VLF waves. Three experiments, one in the nighttime in the absence of D and E layers and two in the daytime in the presence of D and E layers, were performed. X mode HF heaters of slightly different frequencies were transmitted at CW full power. VLF waves at 10 frequencies ranging from 3.5 to 21.5 kHz were generated. The frequency dependencies of the daytime and nighttime radiation intensities are quite similar, but the nighttime radiation is much stronger than the daytime one at the same radiation frequency. The intensity ratio is as large as 9 dB at 11.5 kHz. An experiment directly comparing VLF waves generated by the beat-wave approach and by the amplitude modulation (AM) approach was also conducted. The results rule out the likely contribution of the AM mechanism acting on the electrojet and indicate that beat-wave in the VLF range prefers to be generated in the F region of the ionosphere through the ponderomotive nonlinearity, consistent with the theory. In the nighttime experiment, the ionosphere was underdense to the HF heaters, suggesting a likely setting for effective beat-wave generation of VLF waves by the HF heaters.

  4. Statistical Analysis of Langmuir Waves Associated with Type III Radio Bursts: I. Wind Observations

    Directory of Open Access Journals (Sweden)

    Vidojević S.

    2011-12-01

    Full Text Available Interplanetary electron beams are unstable in the solar wind and they generate Langmuir waves at the local plasma frequency or its harmonic. Radio observations of the waves in the range 4-256 kHz, observed in 1994-2010 with the WAVES experiment onboard the WIND spacecraft, are statistically analyzed. A subset of 36 events with Langmuir waves and type III bursts occurring at the same time was selected. After removal of the background, the remaining power spectral density is modeled by the Pearson system of probability distributions (types I, IV and VI. The Stochastic Growth Theory (SGT predicts log-normal distribution for the power spectrum density of the Langmuir waves. Our results indicate that SGT possibly requires further verification.

  5. design of a small scale wind generator for low wind speed areas

    African Journals Online (AJOL)

    USER

    Most small scale level wind turbine generators are directly driven system, variable speed, and partially ... the best solutions for small-scale wind power plants. Low-speed multi-pole PM generators ..... Designs of the Same Magnet Structure for.

  6. Generating asymptotically plane wave spacetimes

    International Nuclear Information System (INIS)

    Hubeny, Veronika E.; Rangamani, Mukund

    2003-01-01

    In an attempt to study asymptotically plane wave spacetimes which admit an event horizon, we find solutions to vacuum Einstein's equations in arbitrary dimension which have a globally null Killing field and rotational symmetry. We show that while such solutions can be deformed to include ones which are asymptotically plane wave, they do not posses a regular event horizon. If we allow for additional matter, such as in supergravity theories, we show that it is possible to have extremal solutions with globally null Killing field, a regular horizon, and which, in addition, are asymptotically plane wave. In particular, we deform the extremal M2-brane solution in 11-dimensional supergravity so that it behaves asymptotically as a 10-dimensional vacuum plane wave times a real line. (author)

  7. The design of wind turbine for electrical power generation in Malaysian wind characteristics

    International Nuclear Information System (INIS)

    Abas Ab Wahab; Chong Wen Thong

    2000-01-01

    The paper describes the study of a wind turbine for electrical power generation in Malaysia wind characteristics. In this research, the wind turbine is designs based on the local wind characteristics and tries to avoid the problems faced in the past (turbine design, access, manpower and technical). The new wind turbine rotor design for a medium speed wind speed turbine utilises the concept of open-close type of horizontal axis (up-wind) wind turbine is intended to widen the optimum performance range for electrical generation in Malaysia wind characteristics. The wind turbine has been designed to cut-in at a lower speed, and to provide the rotation speed that high enough to run a generator. The analysis and design of new low speed wind turbine blades and open-close turbine rotor and prediction of turbine performance are being detailed in this paper. (Author)

  8. Wave-trains in the solar wind. III

    International Nuclear Information System (INIS)

    Richter, A.K.

    1975-01-01

    Applying an Alfven-Wave-Extended-QRH-approximation and the method of characteristics, the equations of motion for outwardly propagating Alfven waves are solved analytically for three different cases of an azimuthal dependence of the background solar wind, (a) for a pure fast-slow stream configuration, (b) for the situation where the high-speed stream originates from a diverging magnetic field, and (c) for the case of (b) and an initially decreasing density configuration ('coronal hole'). The reaction of these waves on the background state as well as mode-mode coupling effects are neglected. These three solar wind models are discussed shortly. For the superimposed Alfven waves it is found, on an average, that there is a strong azimuthal dependence of all relevant parameters which, correlated with the azimuthal distributions of the solar wind variables, leads to good agreements with observations. The signature of high-speed streams and these correlations could clearly indicate solar wind streams originating from 'coronal holes'. Contrary to the purely radial solar wind, where outwardly propagating Alfven waves are exclusively refracted towards the radial direction, a refraction nearly perpendicular to the direction of the interplanetary magnetic field in the compression region and closely towards the magnetic field direction down the trailing edge and in the low-speed regime is found. (Auth.)

  9. Generating wind fluctuations for Large Eddy Simulation inflow boundary condition

    International Nuclear Information System (INIS)

    Bekele, S.A.; Hangan, H.

    2004-01-01

    Large Eddy Simulation (LES) studies of flows over bluff bodies immersed in a boundary layer wind environment require instantaneous wind characteristics. The influences of the wind environment on the building pressure distribution are a well-established fact in the experimental study of wind engineering. Measured wind data of full or model scale are available only at a limited number of points. A method of obtaining instantaneous wind data at all mesh points of the inlet boundary for LES computation is necessary. Herein previous and new wind inflow generation techniques are presented. The generated wind data is then applied to a LES computation of a channel flow. The characteristics of the generated wind fluctuations in comparison to the measured data and the properties of the flow field computed from these two wind data are discussed. (author)

  10. Analysis of wind energy generation possibilities with various rotor types at disadvantageous wind condition zones

    OpenAIRE

    Bieniek Andrzej

    2017-01-01

    The paper describe possibilities of energy generation using various rotor types but especially with multi-blade wind engine operates in the areas with unfavourable wind condition. The paper presents also wind energy conversion estimation results presented based on proposed solution of multi-blade wind turbine of outer diameter of 4 m. Based on the wind distribution histogram from the disadvantage wind condition zones (city of Basel) and taking into account design and estimated operating index...

  11. Integration of Wave and Offshore Wind Energy in a European Offshore Grid

    DEFF Research Database (Denmark)

    Chozas, Julia Fernandez; Sørensen, H. C.; Korpås, M.

    2010-01-01

    of offshore renewable energy sources. According to this, the paper covers i) public and private initiatives for offshore transmission networks, ii) the synergies between the wave and the offshore wind energy sector within an offshore grid, iii) power transmission options for offshore generation and iv...

  12. Dynamic Analysis of Wind Power Turbine's Tower under the Combined Action of Winds and Waves

    Institute of Scientific and Technical Information of China (English)

    CHENG You-liang; QU Jiang-man; XUE Zhan-pu; JIANG Yan

    2017-01-01

    To deal with the dynamic response problem of offshore wind power tower under the combined action of winds and waves,finite element method is used to analyze the structure and flow field around the outside flange of the segmentation part.The changes of pressure distribution and vorticity about the outside flange are obtained.Focused on the analysis on the change of hydrostatic pressure and temperature of the tower cut surface,contour lines under the combined action of winds and waves are depicted.Results show that the surface of the offshore wind turbine tower presents instable temperature field when it suffers the action of winds and waves loads,the static pressure increases nonlinearly with the increase of altitude,the fluid vorticity around the outside flange follows an parabolic curve approximately.Results provide a reference for the actual monitoring data of the offshore wind turbine tower under the combined action of winds and waves,so as to ensure the normal operation of tower.

  13. MHD waves detected by ice at distances > 28 x 106 km from Comet Halley: Cometary or solar wind origin

    International Nuclear Information System (INIS)

    Tsurutani, B.T.; Brinca, A.L.; Smith, E.J.; Thorne, R.M.; Scarf, F.L.; Gosling, J.T.; Ipavich, F.M.

    1986-01-01

    Spectral analyses of the high resolution magnetic field data are employed to determine if there is evidence of cometary heavy ion pickup when ICE was closest to Halley, ∼28 x 10 6 km. No evidence is found for the presence of heavy ion cyclotron waves. However, from this search, two new wave modes are discovered in the solar wind: electromagnetic ion cyclotron waves and drift mirror mode waves. Both modes have scales of 10 to 60 s (1 to 6 T/sub p/) in the spacecraft frame. The possibility of wave generation by cometary hydrogen pickup is explored. Theoretical arguments and further experimental evidence indicates that cometary origin is improbable. The most likely source is plasma instabilities associated with solar wind stream-stream interactions. VLF electrostatic emissions are found to occur in field minima or at gradients of the drift mirror structures. Possible generation mechanisms of drift mirror mode waves, cyclotron waves and electrostatic waves are discussed

  14. Selecting optimum locations for co-located wave and wind energy farms. Part I: The Co-Location Feasibility index

    International Nuclear Information System (INIS)

    Astariz, S.; Iglesias, G.

    2016-01-01

    Highlights: • New approach to identifying suitable sites for co-located wave and wind farms. • A new tool, the Co-Location Feasibility (CLF) index, is defined. • Its application is analysed by means of a case study off the Danish coast. • Hindcast and measured wave and wind data from 2005 to 2015 are used. • Third-generation models of winds and waves (WAsP and SWAN) are used. - Abstract: Marine energy is poised to play a fundamental role in meeting renewable energy and carbon emission targets thanks to the abundant, and still largely untapped, wave and tidal resources. However, it is often considered difficult and uneconomical – as is usually the case of nascent technologies. Combining various renewables, such as wave and offshore wind energy, has emerged as a solution to improve their competitiveness and in the process overcome other challenges that hinder their development. The objective of this paper is to develop a new approach to identifying suitable sites for co-located wave and wind farms based on the assessment of the available resources and technical constraints, and to illustrate its application by means of a case study off the Danish coast – an area of interest for combining wave and wind energy. The method is based on an ad hoc tool, the Co-Location Feasibility (CLF) index, and is based on a joint characterisation of the wave and wind resources, which takes into account not only the available power but also the correlation between both resources and the power variability. The analysis is carried out based on hindcast data and observations from 2005 to 2015, and using third-generation models of winds and waves – WAsP and SWAN, respectively. Upon selection and ranking, it is found that a number of sites in the study region are indeed suited to realising the synergies between wave and offshore wind energy. The approach developed in this work can be applied elsewhere.

  15. Model 0A wind turbine generator FMEA

    Science.gov (United States)

    Klein, William E.; Lalli, Vincent R.

    1989-01-01

    The results of Failure Modes and Effects Analysis (FMEA) conducted for the Wind Turbine Generators are presented. The FMEA was performed for the functional modes of each system, subsystem, or component. The single-point failures were eliminated for most of the systems. The blade system was the only exception. The qualitative probability of a blade separating was estimated at level D-remote. Many changes were made to the hardware as a result of this analysis. The most significant change was the addition of the safety system. Operational experience and need to improve machine availability have resulted in subsequent changes to the various systems which are also reflected in this FMEA.

  16. Generation Expansion Planning Considering Integrating Large-scale Wind Generation

    DEFF Research Database (Denmark)

    Zhang, Chunyu; Ding, Yi; Østergaard, Jacob

    2013-01-01

    necessitated the inclusion of more innovative and sophisticated approaches in power system investment planning. A bi-level generation expansion planning approach considering large-scale wind generation was proposed in this paper. The first phase is investment decision, while the second phase is production...... optimization decision. A multi-objective PSO (MOPSO) algorithm was introduced to solve this optimization problem, which can accelerate the convergence and guarantee the diversity of Pareto-optimal front set as well. The feasibility and effectiveness of the proposed bi-level planning approach and the MOPSO...

  17. Comparison of simulations and offshore measurement data of a prototype of a floating combined wind and wave energy conversion system

    DEFF Research Database (Denmark)

    Yde, Anders; Larsen, Torben J.; Hansen, Anders Melchior

    2015-01-01

    In this paper, results from comparisons of simulations and measured offshore data from a floating combined wind and wave energy conversion system are presented. The device is a downscaled prototype that consists of a floating platform equipped with ten wave energy absorbers and three wind turbines....... The numerical model of the platform is based on the aeroelastic code, HAWC2, developed by DTU Wind Energy, which is coupled with a special external system that reads the output generated directly by the wave analysis software, WAMIT. The model also includes models for the dynamic mooring lines as well...... as the turbines non-linear yaw and teeter motion behavior. The main focus on the comparison will be on the statistical trends of the platform motion, mooring loads and turbine loads in measurements and simulations during different operational conditions such as increasing wind speed, wave height and wind...

  18. Model-Based Control of a Ballast-Stabilized Floating Wind Turbine Exposed to Wind and Waves

    DEFF Research Database (Denmark)

    Christiansen, Søren

    2013-01-01

    wind turbine, for water depths beyond 50 meters where winds are stronger and less turbulent. A floating wind turbine is subject to not only aerodynamics and wind induced loads, but also to hy-drodynamics and wave induced loads. In contrast to a bottom fixed wind turbine, the floating structure......, the hydrodynamics and the loads change the dynamic behavior of a floating wind turbine. Consequently, conventional wind turbine control cause instabilities on floating wind turbines. This work addresses the control of a floating spar buoy wind turbine, and focuses on the impact of the additional platform dynamics....... A time varying control model is presented based on the wind speed and wave frequency. Estimates of the wind speed and wave frequency are used as scheduling variables in a gain scheduled linear quadratic controller to improve the electrical power production while reducing fatigue. To address the problem...

  19. Structural Flexibility of Large Direct Drive Generators for Wind Turbines

    NARCIS (Netherlands)

    Shrestha, G.

    2013-01-01

    The trend in wind energy is towards large offshore wind farms. This trend has led to the demand for high reliability and large single unit wind turbines. Different energy conversion topologies such as multiple stage geared generators, single stage geared generators and gearless (direct drive)

  20. Interconnector capacity allocation in offshore grids with variable wind generation

    DEFF Research Database (Denmark)

    Schröder, Sascha Thorsten

    2013-01-01

    the interconnector capacity should be allocated for wind generation and for international power trading. The main difficulty arises from the stochastic nature of wind generation: in a case with radial connections to the national coast, the wind park owner has the possibility of aggregating the offshore wind park....... It is concluded that treating offshore generation as a single price zone within the interconnector reduces the wind operator’s ability to pool it with other generation. Furthermore, a single offshore price zone between two markets will always receive the lower spot market price of the neighbouring zones, although...

  1. A Floating Offshore Wind Turbine in Extreme Wave Conditions

    DEFF Research Database (Denmark)

    Wehmeyer, Christof

    in order to include non-linear irregular incident waves as well as non-linear irregular incident waves with an embedded Stream-function wave. A linear background sea state into which a Stream-function wave was embedded was assumed no longer appropriate. Therefore a 2nd order sea state model was developed...... and served as well as the background sea state in which the Stream-function wave was embedded. The combined sea state was then applied in the numerical model in order to investigate the bow tendon responses of the FOWT TLP. A comparison of measured bow mooring responses and the numerically predicted bow......The PhD work evaluated the performance of engineering procedures, used in the design of bottom fixed offshore wind turbines, for the hydrodynamic ULS analysis of a FOWT tension leg platform (TLP). Dynamically sensitive topsides have been included and water depths were considered, where wave shapes...

  2. Wind hazard assessment for Point Lepreau Generating Station

    International Nuclear Information System (INIS)

    Mullin, D.; Moland, M.; Sciaudone, J.C.; Twisdale, L.A.; Vickery, P.J.; Mizzen, D.R.

    2015-01-01

    In response to the CNSC Fukushima Action Plan, NB Power has embarked on a wind hazard assessment for the Point Lepreau Generating Station site that incorporates the latest up to date wind information and modeling. The objective was to provide characterization of the wind hazard from all potential sources and estimate wind-driven missile fragilities and wind pressure fragilities for various structures, systems and components that would provide input to a possible high wind Probabilistic Safety Assessment. The paper will discuss the overall methodology used to assess hazards related to tornadoes, hurricanes and straight-line winds, and site walk-down and hazard/fragility results. (author)

  3. Density Fluctuations in the Solar Wind Driven by Alfvén Wave Parametric Decay

    Science.gov (United States)

    Bowen, Trevor A.; Badman, Samuel; Hellinger, Petr; Bale, Stuart D.

    2018-02-01

    Measurements and simulations of inertial compressive turbulence in the solar wind are characterized by anti-correlated magnetic fluctuations parallel to the mean field and density structures. This signature has been interpreted as observational evidence for non-propagating pressure balanced structures, kinetic ion-acoustic waves, as well as the MHD slow-mode. Given the high damping rates of parallel propagating compressive fluctuations, their ubiquity in satellite observations is surprising and suggestive of a local driving process. One possible candidate for the generation of compressive fluctuations in the solar wind is the Alfvén wave parametric instability. Here, we test the parametric decay process as a source of compressive waves in the solar wind by comparing the collisionless damping rates of compressive fluctuations with growth rates of the parametric decay instability daughter waves. Our results suggest that generation of compressive waves through parametric decay is overdamped at 1 au, but that the presence of slow-mode-like density fluctuations is correlated with the parametric decay of Alfvén waves.

  4. Design and Experiment Analysis of a Direct-Drive Wave Energy Converter with a Linear Generator

    OpenAIRE

    Jing Zhang; Haitao Yu; Zhenchuan Shi

    2018-01-01

    Coastal waves are an abundant nonpolluting and renewable energy source. A wave energy converter (WEC) must be designed for efficient and steady operation in highly energetic ocean environments. A direct-drive wave energy conversion (D-DWEC) system with a tubular permanent magnet linear generator (TPMLG) on a wind and solar photovoltaic complementary energy generation platform is proposed to improve the conversion efficiency and reduce the complexity and device volume of WECs. The operating pr...

  5. Wind Turbine Generator System Acoustic Noise Test Report for the Gaia Wind 11-kW Wind Turbine

    Energy Technology Data Exchange (ETDEWEB)

    Huskey, A.

    2011-11-01

    This report details the acoustic noise test conducted on the Gaia-Wind 11-kW wind turbine at the National Wind Technology Center. The test turbine is a two- bladed, downwind wind turbine with a rated power of 11 kW. The test turbine was tested in accordance with the International Electrotechnical Commission standard, IEC 61400-11 Ed 2.1 2006-11 Wind Turbine Generator Systems -- Part 11 Acoustic Noise Measurement Techniques.

  6. An axisymmetric inertia-gravity wave generator

    Science.gov (United States)

    Maurer, P.; Ghaemsaidi, S. J.; Joubaud, S.; Peacock, T.; Odier, P.

    2017-10-01

    There has been a rich interplay between laboratory experimental studies of internal waves and advancing understanding of their role in the ocean and atmosphere. In this study, we present and demonstrate the concept for a new form of laboratory internal wave generator that can excite axisymmetric wave fields of arbitrary radial structure. The construction and operation of the generator are detailed, and its capabilities are demonstrated through a pair of experiments using a Bessel function and a bourrelet (i.e., ring-shaped) configuration. The results of the experiments are compared with the predictions of an accompanying analytical model.

  7. Protective, Modular Wave Power Generation System

    Energy Technology Data Exchange (ETDEWEB)

    Vvedensky, Jane M.; Park, Robert Y.

    2012-11-27

    The concept of small wave energy conversion modules that can be built into large, scalable arrays, in the same vein as solar panels, has been developed. This innovation lends itself to an organic business and development model, and enables the use of large-run manufacturing technology to reduce system costs. The first prototype module has been built to full-scale, and tested in a laboratory wave channel. The device has been shown to generate electricity and dissipate wave energy. Improvements need to be made to the electrical generator and a demonstration of an array of modules should be made in natural conditions.

  8. Current generation by monochromatic electromagnetic waves

    International Nuclear Information System (INIS)

    Belikov, V.S.; Kolesnichenko, Ya.I.; Plotnik, I.S.

    1983-01-01

    The generation of longitudinal currents in a magnetically confined plasma with travelling monochromatic electromagnetic waves of finite amplitude propagating at some angle to the external magnetic field is considered. By averaging over the particle cyclotron gyration period, the kinetic equation for the distribution function of electrons interacting with an electromagnetic wave is derived. This equation is solved for the case of low-frequency waves, on the assumption that the bounce period of electrons trapped by the wave field is small compared to the typical times of Coulomb collisions (in which case, the driving current is largest). From the solution obtained, analytic expressions for the driving current and the absorbed power, which are valid for a wide range of wave phase velocities, are found. The current drive method considered and the method using the wave packet are compared. (author)

  9. Design Optimization and Evaluation of Different Wind Generator Systems

    DEFF Research Database (Denmark)

    Chen, Zhe; Li, Hui

    2008-01-01

    . In this paper, seven variable speed constant frequency (VSCF) wind generator systems are investigated, namely permanent magnet synchronous generators with the direct-driven (PMSG_DD), the single-stage gearbox (PMSG_1G) and three-stage gearbox (PMSG_3G) concepts, doubly fed induction generators with the three......With rapid development of wind power technologies and significant growth of wind power capacity installed worldwide, various wind generator systems have been developed and built. The objective of this paper is to evaluate various wind generator systems by optimization designs and comparisons......-stage gearbox (DFIG_3G) and with the single-stage gearbox (DFIG_1G), the electricity excited synchronous generator with the direct-driven (EESG_DD), and the VSCF squirrel cage induction generator with the three-stage gearbox (SCIG_3G). Firstly, the design models of wind turbines, three/single stage gearbox...

  10. Wind turbine/generator set and method of making same

    Science.gov (United States)

    Bevington, Christopher M.; Bywaters, Garrett L.; Coleman, Clint C.; Costin, Daniel P.; Danforth, William L.; Lynch, Jonathan A.; Rolland, Robert H.

    2013-06-04

    A wind turbine comprising an electrical generator that includes a rotor assembly. A wind rotor that includes a wind rotor hub is directly coupled to the rotor assembly via a simplified connection. The wind rotor and generator rotor assembly are rotatably mounted on a central spindle via a bearing assembly. The wind rotor hub includes an opening having a diameter larger than the outside diameter of the central spindle adjacent the bearing assembly so as to allow access to the bearing assembly from a cavity inside the wind rotor hub. The spindle is attached to a turret supported by a tower. Each of the spindle, turret and tower has an interior cavity that permits personnel to traverse therethrough to the cavity of the wind rotor hub. The wind turbine further includes a frictional braking system for slowing, stopping or keeping stopped the rotation of the wind rotor and rotor assembly.

  11. On the dependence of sea surface roughness on wind waves

    DEFF Research Database (Denmark)

    Johnson, H.K.; Højstrup, J.; Vested, H.J.

    1998-01-01

    that calculations of the wind friction velocities using the wave-spectra-dependent expression of Hansen and Larsen agrees quite well with measured values during RASEX. It also gives a trend in Charnock parameter consistent with that found by combining the field data. Last, calculations using a constant Charnock...

  12. Design Study of Fully Superconducting Wind Turbine Generators

    DEFF Research Database (Denmark)

    Song, Xiaowei (Andy); Mijatovic, Nenad; Jensen, Bogi Bech

    2015-01-01

    In this paper, two fully superconducting generators employing MgB2 armature winding, with YBCO and MgB2 field winding respectively, are presented and analyzed. The ac loss in armature winding is estimated, and a simple comparative study is carried out. The results show that both electromagnetic...... designs for fully superconducting generators are promising with respect to the power density. However, the cost of removing ac loss in armature winding is as high as $900 000. It is also noted that with the current price of YBCO tape, the generator employing MgB 2 field winding would have lower cost....

  13. Investigation of surge protective devices operation of a wind generator

    International Nuclear Information System (INIS)

    Dimitrov, D.; Vasileva, M.

    2008-01-01

    The interest to the investments in a wind energetics increases in the last years. The wind energetics is the fastest developing direction in the energetics in global scale. The wind energy is more attractive because its prices are lower in comparison of the other technologies for generating energy. The right choice of the surge protective devices has the important meaning on building and exploitation of the wind generators. The aim of this paper is investigation of the surge protective devices operation when they are installation to a wind generator. (authors)

  14. Power Quality Improvements in Wind Diesel Power Generation System

    Directory of Open Access Journals (Sweden)

    Omar Feddaoui

    2015-08-01

    Full Text Available Generation of electricity using diesel is costly for small remote isolated communities. At remote location electricity generation from renewable energy such as wind can help reduce the overall operating costs by reducing the fuel costs. However, the penetration of wind power into small diesel-based grids is limited because of its effect on power quality and reliability. This paper focuses on the combination of Wind Turbine and Diesel Generator systems for sustained power generation, to improve the power quality of wind generation system. The performances of the optimal control structure are assessed and discussed by means of a set of simulations.

  15. Persistent gravity wave coupling from the stratosphere to the MLT versus secondary wave generation in Antarctica

    Science.gov (United States)

    Zhao, J.; Geraghty, I.; Chu, X.; Vadas, S.; Becker, E.; Harvey, V. L.; Jones, R. M.; Chen, C.; Lu, X.

    2017-12-01

    After Antarctic persistent gravity waves (GWs) in the Mesosphere and Lower Thermosphere (MLT) were discovered from lidar observations [Chen et al., 2013, 2016], secondary wave generation theory was proposed to explain the source. Here we perform a source investigation of such persistent GWs through analyzing both stratospheric and MLT GWs at McMurdo using temperature measurements (30 - 50 km, year 2011 - 2015) obtained by Fe Boltzmann lidar. In the stratosphere, GW vertical wavelengths (λ) and periods exhibit seasonal cycles with winter maxima and summer minima, which linearly correlated with mean zonal wind velocities. GWs dissipate more in winter than in summer due to larger wave amplitudes. The potential energy density (Ep) are anti-correlated with wind rotation angles but positively correlated with surface and stratospheric winds. Critical level filtering, in-situ generation of GWs, and wave saturation changes play roles in Ep seasonal variations (winter maxima and summer minima). The large increase of Ep from summer to winter possibly results from the decrease in critical level filtering. The gradual variations of Ep from Mar to Oct are likely related both to the increased λ towards winter, allowing larger wave amplitudes before saturation, and to in-situ GW generation via geostrophic adjustment, secondary GW generation. Large Ep occur when McMurdo is inside the jet stream core 5-24º poleward from vortex edge. In winter MLT, the persistent GWs cause larger temperature perturbations (± 30 K, compared to ± 10 K in the stratosphere) with longer λ (23.5 km) and larger vertical phase speeds (1.8 m/s). More waves (95.4%) show downward phase progression compared to the stratospheric GWs (70.4%). Since the inferred horizontal wavelength of stratospheric GWs (350 - 450 km) are much shorter than those of the persistent GWs in the MLT (1000 - 2000 km), the dominant stratospheric GWs are not the direct source of the MLT persistent GWs. Secondary wave generation

  16. Turbulence Simulation of Laboratory Wind-Wave Interaction in High Winds and Upscaling to Ocean Conditions

    Science.gov (United States)

    2016-12-22

    Oceanogr., 46, 1377-1397 Cebeci, T. & P. Bradshaw, 1988: physical and computational aspects of convective heat transfer , Springer-Verlag, p.487...on surface properties and flow separation. Strongly-forced wind seas are characterized by enhanced group modulation , as significant additional...energy flux from the wind augments the hydrodynamic modulations . Using compact steep chirped wave packets, we investigated for the first time the

  17. Design of High Performance Permanent-Magnet Synchronous Wind Generators

    Directory of Open Access Journals (Sweden)

    Chun-Yu Hsiao

    2014-11-01

    Full Text Available This paper is devoted to the analysis and design of high performance permanent-magnet synchronous wind generators (PSWGs. A systematic and sequential methodology for the design of PMSGs is proposed with a high performance wind generator as a design model. Aiming at high induced voltage, low harmonic distortion as well as high generator efficiency, optimal generator parameters such as pole-arc to pole-pitch ratio and stator-slot-shoes dimension, etc. are determined with the proposed technique using Maxwell 2-D, Matlab software and the Taguchi method. The proposed double three-phase and six-phase winding configurations, which consist of six windings in the stator, can provide evenly distributed current for versatile applications regarding the voltage and current demands for practical consideration. Specifically, windings are connected in series to increase the output voltage at low wind speed, and in parallel during high wind speed to generate electricity even when either one winding fails, thereby enhancing the reliability as well. A PMSG is designed and implemented based on the proposed method. When the simulation is performed with a 6 Ω load, the output power for the double three-phase winding and six-phase winding are correspondingly 10.64 and 11.13 kW. In addition, 24 Ω load experiments show that the efficiencies of double three-phase winding and six-phase winding are 96.56% and 98.54%, respectively, verifying the proposed high performance operation.

  18. Unraveling Climatic Wind and Wave Trends in the Red Sea Using Wave Spectra Partitioning

    KAUST Repository

    Langodan, Sabique

    2017-12-27

    The wind and wave climatology of the Red Sea is derived from a validated 30-year high-resolution model simulation. After describing the relevant features of the basin, the main wind and wave systems are identified by using an innovative spectral partition technique to explain their genesis and characteristics. In the northern part of the sea, wind and waves of the same intensity are present throughout the year, while the central and southern zones are characterized by a marked seasonality. The partition technique allows the association of a general decrease in the energy of the different wave systems with a specific weather pattern. The most intense decrease is found in the northern storms, which are associated with meteorological pulses from the Mediterranean Sea.

  19. Unraveling Climatic Wind and Wave Trends in the Red Sea Using Wave Spectra Partitioning

    KAUST Repository

    Langodan, Sabique; Cavaleri, Luigi; Pomaro, Angela; Portilla, Jesus; Abualnaja, Yasser; Hoteit, Ibrahim

    2017-01-01

    The wind and wave climatology of the Red Sea is derived from a validated 30-year high-resolution model simulation. After describing the relevant features of the basin, the main wind and wave systems are identified by using an innovative spectral partition technique to explain their genesis and characteristics. In the northern part of the sea, wind and waves of the same intensity are present throughout the year, while the central and southern zones are characterized by a marked seasonality. The partition technique allows the association of a general decrease in the energy of the different wave systems with a specific weather pattern. The most intense decrease is found in the northern storms, which are associated with meteorological pulses from the Mediterranean Sea.

  20. Analysis of wind energy generation possibilities with various rotor types at disadvantageous wind condition zones

    Science.gov (United States)

    Bieniek, Andrzej

    2017-10-01

    The paper describe possibilities of energy generation using various rotor types but especially with multi-blade wind engine operates in the areas with unfavourable wind condition. The paper presents also wind energy conversion estimation results presented based on proposed solution of multi-blade wind turbine of outer diameter of 4 m. Based on the wind distribution histogram from the disadvantage wind condition zones (city of Basel) and taking into account design and estimated operating indexes of the considered wind engine rotor an annual energy generation was estimated. Also theoretical energy generation using various types of wind turbines operates at disadvantage wind conditions zones were estimated and compared. The conducted analysis shows that introduction of multi-blade wind rotor instead of the most popular 3- blades or vertical axis rotors results of about 5% better energy generation. Simultaneously there are energy production also at very disadvantages wind condition at wind speed lower then 4 m s-1. Based on considered construction of multi-blade wind engine the rise of rotor mounting height from 10 to 30 m results with more then 300 % better results in terms of electric energy generation.

  1. Analysis of wind energy generation possibilities with various rotor types at disadvantageous wind condition zones

    Directory of Open Access Journals (Sweden)

    Bieniek Andrzej

    2017-01-01

    Full Text Available The paper describe possibilities of energy generation using various rotor types but especially with multi-blade wind engine operates in the areas with unfavourable wind condition. The paper presents also wind energy conversion estimation results presented based on proposed solution of multi-blade wind turbine of outer diameter of 4 m. Based on the wind distribution histogram from the disadvantage wind condition zones (city of Basel and taking into account design and estimated operating indexes of the considered wind engine rotor an annual energy generation was estimated. Also theoretical energy generation using various types of wind turbines operates at disadvantage wind conditions zones were estimated and compared. The conducted analysis shows that introduction of multi-blade wind rotor instead of the most popular 3- blades or vertical axis rotors results of about 5% better energy generation. Simultaneously there are energy production also at very disadvantages wind condition at wind speed lower then 4 ms-1. Based on considered construction of multi-blade wind engine the rise of rotor mounting height from 10 to 30 m results with more then 300 % better results in terms of electric energy generation.

  2. Turbulence and Waves as Sources for the Solar Wind

    Science.gov (United States)

    Cranmer, S. R.

    2008-05-01

    Gene Parker's insights from 50 years ago provided the key causal link between energy deposition in the solar corona and the acceleration of solar wind streams. However, the community is still far from agreement concerning the actual physical processes that give rise to this energy. It is still unknown whether the solar wind is fed by flux tubes that remain open (and are energized by footpoint-driven wavelike fluctuations) or if mass and energy is input more intermittently from closed loops into the open-field regions. No matter the relative importance of reconnections and loop-openings, though, we do know that waves and turbulent motions are present everywhere from the photosphere to the heliosphere, and it is important to determine how they affect the mean state of the plasma. In this presentation, I will give a summary of wave/turbulence models that seem to succeed in explaining the time-steady properties of the corona (and the fast and slow solar wind). The coronal heating and solar wind acceleration in these models comes from anisotropic turbulent cascade, which is driven by the partial reflection of low-frequency Alfven waves propagating along the open magnetic flux tubes. Specifically, a 2D model of coronal holes and streamers at solar minimum reproduces the latitudinal bifurcation of slow and fast streams seen by Ulysses. The radial gradient of the Alfven speed affects where the waves are reflected and damped, and thus whether energy is deposited below or above Parker's critical point. As predicted by earlier studies, a larger coronal expansion factor gives rise to a slower and denser wind, higher temperature at the coronal base, less intense Alfven waves at 1 AU, and correlative trends for commonly measured ratios of ion charge states and FIP-sensitive abundances that are in general agreement with observations. Finally, I will outline the types of future observations that would be most able to test and refine these ideas.

  3. Coupling Atmosphere and Waves for Coastal Wind Turbine Design

    DEFF Research Database (Denmark)

    Bolanos, Rodolfo; Larsén, Xiaoli Guo; Petersen, Ole S.

    2014-01-01

    model (MIKE 21 SW) are implemented for the North Sea in order to consider wave effects on roughness. The objective is to see the reaction of an atmospheric model to the water surface description through offline coupling. A comparison with three simplified roughness formulations embedded in WRF showed......Offshore wind farms in coastal areas are considered by the Danish government to contribute to the goal of having 50% of the energy consumption from renewable sources by 2025. Therefore, new coastal developments will take place in Danish areas. The impact of waves on atmosphere is most often...... described by roughness length, which is typically determined by the Charnock formulation. This simplification in many atmospheric models has been shown to bring bias in the estimation of the extreme wind. Some wave-dependent formulations have been reported to overestimate the drag coefficient and roughness...

  4. Alternative methods of modeling wind generation using production costing models

    International Nuclear Information System (INIS)

    Milligan, M.R.; Pang, C.K.

    1996-08-01

    This paper examines the methods of incorporating wind generation in two production costing models: one is a load duration curve (LDC) based model and the other is a chronological-based model. These two models were used to evaluate the impacts of wind generation on two utility systems using actual collected wind data at two locations with high potential for wind generation. The results are sensitive to the selected wind data and the level of benefits of wind generation is sensitive to the load forecast. The total production cost over a year obtained by the chronological approach does not differ significantly from that of the LDC approach, though the chronological commitment of units is more realistic and more accurate. Chronological models provide the capability of answering important questions about wind resources which are difficult or impossible to address with LDC models

  5. A Floating Offshore Wind Turbine in Extreme Wave Conditions

    DEFF Research Database (Denmark)

    Wehmeyer, Christof

    is an expected maximum wave in accordance with a Rayleigh distribution. The maximum waves are numerically represented by embedded Stream-function waves. The author compares the resulting bow tendon loading of the hybrid model to the measured responses, as a key performance indicator. 90% to 95% of the loads show...... a satisfying match, though the hybrid model over predicts the remaining 5% to 10% maximum loads by 32%, 34% and 29% for a linear irregular sea state, a nonlinear irregular sea state and a nonlinear irregular sea state with an embedded Stream-function wave, respectively. The limited number of sea states during...... important aspects, which make them non-conservative in use for FOWT: (A) The offshore wind industry intends to install floating structures at much lower water depth (from 50m onwards), than the offshore oil & gas industry (from 300m onwards). In such cases a linear wave theory approach might...

  6. Design and development of direct drive generators for wind turbines

    International Nuclear Information System (INIS)

    Nagrial, M.; Hellany, A.

    2011-01-01

    This paper discusses various options for wind generators in modern wind turbines without any gearbox. Various power converter configurations are also discussed. The design of modern and efficient variable speed generators is also proposed. The design of a novel permanent magnet generator is also given. (author)

  7. Assessment of wind power generation along the coast of Ghana

    Energy Technology Data Exchange (ETDEWEB)

    Adaramola, Muyiwa S., E-mail: muyiwa.adaramola@umb.no [Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences, Ås (Norway); Agelin-Chaab, Martin [Department of Automotive, Mechanical and Manufacturing Engineering, University of Ontario Institute of Technology, Oshawa, ON (Canada); Paul, Samuel S. [REHAU Industries, Winnipeg, Manitoba (Canada)

    2014-01-15

    Highlights: • The wind energy and its economic viability along the coastal region of Ghana are examined. • Wind resource along the coastal region of Ghana fall into Class 2 or less wind resource. • Wind turbine with rated speed from 9 to 11 m/s is suggested for wind power development. • The unit cost of wind generated electricity is found be between 0.0732 GH¢/kW h and 0.2905 GH¢/kW h. - Abstract: This study examined the wind energy potential and the economic viability of using wind turbine for electricity generation in selected locations along the coastal region of Ghana. The two-parameter Weibull probability density function was employed to analyze the wind speed data obtained from the Ghana Energy Commission. The energy output and unit cost of electricity generated from medium size commercial wind turbine models with rated powers ranging from 50 kW to 250 kW were determined. It was found that the wind resource along the coastal region of Ghana can be classified into Class 2 or less wind resource which indicate that this resource in this area is marginally suitable for large scale wind energy development or suitable for small scale applications and be useful as part of hybrid energy system. It was further observed that wind turbine with designed cut-in wind speed of less than 3 m/s and moderate rated wind speed between 9 and 11 m/s is more suitable for wind energy development along the coastal region of Ghana. Based on the selected wind turbine and assumptions used in this study, it was estimated that the unit cost of electricity varied between 0.0695 GH¢/kW h and 0.2817 GH¢/kW h.

  8. Assessment of wind power generation along the coast of Ghana

    International Nuclear Information System (INIS)

    Adaramola, Muyiwa S.; Agelin-Chaab, Martin; Paul, Samuel S.

    2014-01-01

    Highlights: • The wind energy and its economic viability along the coastal region of Ghana are examined. • Wind resource along the coastal region of Ghana fall into Class 2 or less wind resource. • Wind turbine with rated speed from 9 to 11 m/s is suggested for wind power development. • The unit cost of wind generated electricity is found be between 0.0732 GH¢/kW h and 0.2905 GH¢/kW h. - Abstract: This study examined the wind energy potential and the economic viability of using wind turbine for electricity generation in selected locations along the coastal region of Ghana. The two-parameter Weibull probability density function was employed to analyze the wind speed data obtained from the Ghana Energy Commission. The energy output and unit cost of electricity generated from medium size commercial wind turbine models with rated powers ranging from 50 kW to 250 kW were determined. It was found that the wind resource along the coastal region of Ghana can be classified into Class 2 or less wind resource which indicate that this resource in this area is marginally suitable for large scale wind energy development or suitable for small scale applications and be useful as part of hybrid energy system. It was further observed that wind turbine with designed cut-in wind speed of less than 3 m/s and moderate rated wind speed between 9 and 11 m/s is more suitable for wind energy development along the coastal region of Ghana. Based on the selected wind turbine and assumptions used in this study, it was estimated that the unit cost of electricity varied between 0.0695 GH¢/kW h and 0.2817 GH¢/kW h

  9. On the spatial hedging effectiveness of German wind power futures for wind power generators

    DEFF Research Database (Denmark)

    Christensen, Troels Sønderby; Pircalabu, Anca

    2018-01-01

    The wind power futures recently introduced on the German market fill the gap of a standardized product that addresses directly the volume risk in wind power trading. While the German wind power futures entail risk-reducing benefits for wind power generators generally speaking, it remains unclear...... the extent of these benefits across wind farms with different geographical locations. In this paper, we consider the wind utilization at 31 different locations in Germany, and for each site, we propose a copula model for the joint behavior of the site-specific wind index and the overall German wind index....... Our results indicate that static mixture copulas are preferred to the stand-alone copula models usually employed in the economic literature. Further, we find evidence of asymmetric dependence and upper tail dependence. To quantify the benefits of wind power futures at each wind site, we perform...

  10. Power Generation Using Mechanical Wave Energy Converter

    Directory of Open Access Journals (Sweden)

    Srinivasan Chandrasekaran

    2012-03-01

    Full Text Available Ocean wave energy plays a significant role in meeting the growing demand of electric power. Economic, environmental, and technical advantages of wave energy set it apart from other renewable energy resources. Present study describes a newly proposed Mechanical Wave Energy Converter (MEWC that is employed to harness heave motion of floating buoy to generate power. Focus is on the conceptual development of the device, illustrating details of component level analysis. Employed methodology has many advantages such as i simple and easy fabrication; ii easy to control the operations during rough weather; and iii low failure rate during normal sea conditions. Experimental investigations carried out on the scaled model of MWEC show better performance and its capability to generate power at higher efficiency in regular wave fields. Design Failure Mode and Effect Analysis (FMEA shows rare failure rates for all components except the floating buoy.

  11. Extreme wave and wind response predictions

    DEFF Research Database (Denmark)

    Jensen, Jørgen Juncher; Olsen, Anders S.; Mansour, Alaa E.

    2011-01-01

    codes and the short duration of the time domain simulations needed (typically 60–300s to cover the hydro- and aerodynamic memory effects in the response) the calculation of the mean out-crossing rates of a given response is fast. Thus non-linear effects can be included. Furthermore, the FORM analysis...... also identifies the most probable wave episodes leading to given responses.Because of the linearization of the failure surface in the FORM procedure the results are only asymptotically exact and thus MCS often also needs to be performed. In the present paper a scaling property inherent in the FORM...

  12. Vortex, ULF wave and Aurora Observation after Solar Wind Dynamic Pressure Change

    Science.gov (United States)

    Shi, Q.

    2017-12-01

    Here we will summarize our recent study and show some new results on the Magnetosphere and Ionosphere Response to Dynamic Pressure Change/disturbances in the Solar Wind and foreshock regions. We study the step function type solar wind dynamic pressure change (increase/decrease) interaction with the magnetosphere using THEMIS satellites at both dayside and nightside in different geocentric distances. Vortices generated by the dynamic pressure change passing along the magnetopause are found and compared with model predictions. ULF waves and vortices are excited in the dayside and nightside plasma sheet when dynamic pressure change hit the magnetotail. The related ionospheric responses, such as aurora and TCVs, are also investigated. We compare Global MHD simulations with the observations. We will also show some new results that dayside magnetospheric FLRs might be caused by foreshock structures.Shi, Q. Q. et al. (2013), THEMIS observations of ULF wave excitation in the nightside plasma sheet during sudden impulse events, J. Geophys. Res. Space Physics, 118, doi:10.1029/2012JA017984. Shi, Q. Q. et al. (2014), Solar wind pressure pulse-driven magnetospheric vortices and their global consequences, J. Geophys. Res. Space Physics, 119, doi:10.1002/2013JA019551. Tian, A.M. et al.(2016), Dayside magnetospheric and ionospheric responses to solar wind pressure increase: Multispacecraft and ground observations, J. Geophys. Res., 121, doi:10.1002/2016JA022459. Shen, X.C. et al.(2015), Magnetospheric ULF waves with increasing amplitude related to solar wind dynamic pressure changes: THEMIS observations, J. Geophys. Res., 120, doi:10.1002/2014JA020913Zhao, H. Y. et al. (2016), Magnetospheric vortices and their global effect after a solar wind dynamic pressure decrease, J. Geophys. Res. Space Physics, 121, doi:10.1002/2015JA021646. Shen, X. C., et al. (2017), Dayside magnetospheric ULF wave frequency modulated by a solar wind dynamic pressure negative impulse, J. Geophys. Res

  13. Trading wind generation from short-term probabilistic forecasts of wind power

    DEFF Research Database (Denmark)

    Pinson, Pierre; Chevallier, Christophe; Kariniotakis, Georges

    2007-01-01

    Due to the fluctuating nature of the wind resource, a wind power producer participating in a liberalized electricity market is subject to penalties related to regulation costs. Accurate forecasts of wind generation are therefore paramount for reducing such penalties and thus maximizing revenue......, as well as on modeling of the sensitivity a wind power producer may have to regulation costs. The benefits resulting from the application of these strategies are clearly demonstrated on the test case of the participation of a multi-MW wind farm in the Dutch electricity market over a year....... participation. Such strategies permit to further increase revenues and thus enhance competitiveness of wind generation compared to other forms of dispatchable generation. This paper formulates a general methodology for deriving optimal bidding strategies based on probabilistic forecasts of wind generation...

  14. Stability improvement of induction generator-based wind turbine systems

    DEFF Research Database (Denmark)

    Chen, Zhe; Hu, Y.; Blaabjerg, Frede

    2007-01-01

    The stability improvement of induction-generator-based wind turbine systems under power system fault conditions has been studied. Two types of generators are considered, namely rotor short-circuited induction generators and dynamic slip-controlled wound rotor induction generators. The factors...... affecting the stability are analysed. The characteristics of the induction-generator-based wind turbines are described, and possible methods of improving stability of the wind generators are discussed. The system modelling is presented, and then the discussed methods of improving stability are investigated...

  15. On The Implications of Atmospheric Gravity Waves on Wind Power

    OpenAIRE

    Norris, Luke

    2011-01-01

    In view of the rapidly rising cost of fossil fuels and concerns over climate change, there can be little doubt that renewable energy is to play a large role in the future of our economic development. The impact of Atmospheric Gravity Waves (AGWs) on wind power is, at best, unclear. In this research, AGWs are successfully modelled both in theoretical and real world environments using the WindSim software package which has revealed a potential 7.4% drop in annual power output as a direct ...

  16. Ion acoustic waves and related plasma observations in the solar wind

    International Nuclear Information System (INIS)

    Gurnett, D.A.; Marsch, E.; Pilipp, W.; Schwenn, R.; Rosenbauer, H.

    1979-01-01

    This paper presents an investigation of solar wind ion acoustic waves and their relationship to the macroscopic and microscopic characteristics of the solar wind plasma. Comparisons with the overall solar wind corotational structure show that the most intense ion acoustic waves usually occur in the low-velocity regions ahead of high-speed solar wind streams. Of the detailed plasma parameters investigated, the ion acoustic wave intensities are found to be most closely correlated with the electron to proton temperature ratio T/sub e//T/sub p/ and with the electron heat flux. Investigations of the detailed electron and proton distribution functions also show that the ion acoustic waves usually occur in regions with highly non-Maxwellian distributions characteristic of double-proton streams. The distribution functions for the double-proton streams are usually not resolved into two clearly defined peaks, but rather they appear as a broad shoulder on the main proton distribution. Two main mechanisms, an electron heat flux instability and a double-ion beam instability, are considered for generating the ion-acoustic-like waves observed in the solar wind. Both mechanisms have favorable and unfavorable features. The electron heat flux mechanism can account for the observed waves at moderate to large ratios of T/sub e//T/sub p/ but has problems when T/sub e//T/sub p/ is small, as sometimes occurs. The ion beam instability appears to provide more flexibility on the T/sub e//T/sub p/ ratio; however detailed comparisons using observed distribution functions indicate that the ion beam mode is usually stable. Possible resolutions of these difficulties are discussed

  17. EXPERIMENTAL DETERMINATION OF WHISTLER WAVE DISPERSION RELATION IN THE SOLAR WIND

    Energy Technology Data Exchange (ETDEWEB)

    Stansby, D.; Horbury, T. S.; Chen, C. H. K.; Matteini, L., E-mail: david.stansby14@imperial.ac.uk [Department of Physics, Imperial College London, London SW7 2AZ (United Kingdom)

    2016-09-20

    The origins and properties of large-amplitude whistler wavepackets in the solar wind are still unclear. In this Letter, we utilize single spacecraft electric and magnetic field waveform measurements from the ARTEMIS mission to calculate the plasma frame frequency and wavevector of individual wavepackets over multiple intervals. This allows direct comparison of experimental measurements with theoretical dispersion relations to identify the observed waves as whistler waves. The whistlers are right-hand circularly polarized, travel anti-sunward, and are aligned with the background magnetic field. Their dispersion is strongly affected by the local electron parallel beta in agreement with linear theory. The properties measured are consistent with the electron heat flux instability acting in the solar wind to generate these waves.

  18. Dependence of Wave-Breaking Statistics on Wind Stress and Wave Development

    Science.gov (United States)

    Katsaros, Kristina B.; Atakturk, Serhad S.

    1992-01-01

    Incidence of wave breaking for pure wind driven waves has been studied on Lake Washington at wind speeds up to 8 m/s. Video recordings were employed to identify and categorize the breaking events in terms of micro-scale, spilling and plunging breakers. These events were correlated with the magnitude of the wave spectrum measured with a resistance wire wave gauge and band pass filtered between 6 and 10 Hz. An equivalent percentage of breaking crests were found for spilling and plunging events. Wave forcing as measured by wind stress (or friction velocity, u(sub *), squared) and by inverse wave age, u(sub *)/Cp where Cp is the phase velocity of the waves at the peak of the frequency spectrum, were found to be good prerictors of percentage of breaking crests. When combined in a two parameter regression, those two variables gave small standard deviation and had a high correlation coefficient (66 percent). The combination of u(sub *)(exp 2) and u(sub *)/Cp can be understood in physical terms. Furthermore, for the larger values of u(sub *)(exp 2) the dependence of wave braking and wave age was stronger than at the low end of the values u(sub *)(exp 2) and u(sub *)/Cp. Thus, both the level of wave development as determined by inverse wave age, which we may term relative wind effectiveness for wave forcing and the wind forcing on the water surface determine the incidence of wave breaking. Substituting U(sub 10)(sup 3.75) (which is the dependence of whitecap cover found by Monahan and coworkers) an equivalent correlation was found to the prediction by u(sub *)(exp 2). Slightly better standard deviation value and higher correlation coefficient were found by using a Reynolds number as predictor. A two-parameter regression involving u(sub *)(exp 2) and a Reynold's number proposed by Toba and his colleagues which relates u(sub *)(exp 2) and peak wave frequency, improves the correlation even more but is less easy to interpret in physical terms. The equivalent percentage of

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-11-01

    This report summarizes the results of a safety and function test that NREL conducted on the Entegrity EW50 wind turbine. This test was conducted in accordance with the International Electrotechnical Commissions' (IEC) standard, Wind Turbine Generator System Part 2: Design requirements for small wind turbines, IEC 61400-2 Ed.2.0, 2006-03.

  20. Hybrid biomass-wind power plant for reliable energy generation

    International Nuclear Information System (INIS)

    Perez-Navarro, A.; Alfonso, D.; Alvarez, C.; Ibanez, F.; Sanchez, C.; Segura, I.

    2010-01-01

    Massive implementation of renewable energy resources is a key element to reduce CO 2 emissions associated to electricity generation. Wind resources can provide an important alternative to conventional electricity generation mainly based on fossil fuels. However, wind generators are greatly affected by the restrictive operating rules of electricity markets because, as wind is naturally variable, wind generators may have serious difficulties on submitting accurate generation schedules on a day ahead basis, and on complying with scheduled obligations in real-time operation. In this paper, an innovative system combining a biomass gasification power plant, a gas storage system and stand-by generators to stabilize a generic 40 MW wind park is proposed and evaluated with real data. The wind park power production model is based on real data about power production of a Spanish wind park and a probabilistic approach to quantify fluctuations and so, power compensation needs. The hybrid wind-biomass system is analysed to obtain main hybrid system design parameters. This hybrid system can mitigate wind prediction errors and so provide a predictable source of electricity. An entire year cycle of hourly power compensations needs has been simulated deducing storage capacity, extra power needs of the biomass power plant and stand-by generation capacity to assure power compensation during critical peak hours with acceptable reliability. (author)

  1. Stochastic generation of hourly wind speed time series

    International Nuclear Information System (INIS)

    Shamshad, A.; Wan Mohd Ali Wan Hussin; Bawadi, M.A.; Mohd Sanusi, S.A.

    2006-01-01

    In the present study hourly wind speed data of Kuala Terengganu in Peninsular Malaysia are simulated by using transition matrix approach of Markovian process. The wind speed time series is divided into various states based on certain criteria. The next wind speed states are selected based on the previous states. The cumulative probability transition matrix has been formed in which each row ends with 1. Using the uniform random numbers between 0 and 1, a series of future states is generated. These states have been converted to the corresponding wind speed values using another uniform random number generator. The accuracy of the model has been determined by comparing the statistical characteristics such as average, standard deviation, root mean square error, probability density function and autocorrelation function of the generated data to those of the original data. The generated wind speed time series data is capable to preserve the wind speed characteristics of the observed data

  2. Simulation of Irregular Waves and Wave Induced Loads on Wind Power Plants in Shallow Water

    Energy Technology Data Exchange (ETDEWEB)

    Trumars, Jenny [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Water Environment Transport

    2004-05-01

    The essay gives a short introduction to waves and discusses the problem with non-linear waves in shallow water and how they effect an offshore wind energy converter. The focus is on the realisation of non-linear waves in the time domain from short-term statistics in the form of a variance density spectrum of the wave elevation. For this purpose the wave transformation from deep water to the near to shore site of a wind energy farm at Bockstigen has been calculated with the use of SWAN (Simulating Waves Near Shore). The result is a wave spectrum, which can be used as input to the realisation. The realisation of waves is done by perturbation theory to the first and second-order. The properties calculated are the wave elevation, water particle velocity and acceleration. The wave heights from the second order perturbation equations are higher than those from the first order perturbation equations. This is also the case for the water particle kinematics. The increase of variance is significant between the first order and the second order realisation. The calculated wave elevation exhibits non-linear features as the peaks become sharper and the troughs flatter. The resulting forces are calculated using Morison's equation. For second order force and base moment there is an increase in the maximum values. The force and base moment are largest approximately at the zero up and down crossing of the wave elevation. This indicates an inertia dominated wave load. So far the flexibility and the response of the structure have not been taken into account. They are, however, of vital importance. For verification of the wave model the results will later on be compared with measurements at Bockstigen off the coast of Gotland in the Baltic Sea.

  3. Wave Run-Up on Offshore Wind Turbines

    DEFF Research Database (Denmark)

    Ramirez, Jorge Robert Rodriguez

    to the cylinder. Based on appropriate analysis the collected data has been analysed with the stream function theory to obtain the relevant parameters for the use of the predicted wave run-up formula. An analytical approach has been pursued and solved for individual waves. Maximum run-up and 2% run-up were studied......This study has investigated the interaction of water waves with a circular structure known as wave run-up phenomenon. This run-up phenomenon has been simulated by the use of computational fluid dynamic models. The numerical model (NS3) used in this study has been verified rigorously against...... a number of cases. Regular and freak waves have been generated in a numerical wave tank with agentle slope in order to address the study of the wave run-up on a circular cylinder. From the computational side it can be said that it is inexpensive. Furthermore, the comparison of the current numerical model...

  4. Wave Run-Up on Offshore Wind Turbines

    DEFF Research Database (Denmark)

    Ramirez, Jorge Robert Rodriguez

    to the cylinder. Based on appropriate analysis the collected data has been analysed with the stream function theory to obtain the relevant parameters for the use of the predicted wave run-up formula. An analytical approach has been pursued and solved for individual waves. Maximum run-up and 2% run-up were studied......This study has investigated the interaction of water waves with a circular structure known as wave run-up phenomenon. This run-up phenomenon has been simulated by the use of computational fluid dynamic models. The numerical model (NS3) used in this study has been verified rigorously against...... a number of cases. Regular and freak waves have been generated in a numerical wave tank with a gentle slope in order to address the study of the wave run-up on a circular cylinder. From the computational side it can be said that it is inexpensive. Furthermore, the comparison of the current numerical model...

  5. A Note on the Effect of Wind Waves on Vertical Mixing in Franks Tract, Sacramento–San Joaquin Delta, California

    Directory of Open Access Journals (Sweden)

    Nicole L. Jones

    2008-06-01

    Full Text Available A one-dimensional numerical model that simulates the effects of whitecapping waves was used to investigate the importance of whitecapping waves to vertical mixing at a 3-meter-deep site in Franks Tract in the Sacramento-San Joaquin Delta over an 11-day period. Locally-generated waves of mean period approximately 2 s were generated under strong wind conditions; significant wave heights ranged from 0 to 0.3 m. A surface turbulent kinetic energy flux was used to model whitecapping waves during periods when wind speeds > 5 m s-1 (62% of observations. The surface was modeled as a wind stress log-layer for the remaining 38% of the observations. The model results demonstrated that under moderate wind conditions (5–8 m s-1 at 10 m above water level, and hence moderate wave heights, whitecapping waves provided the dominant source of turbulent kinetic energy to only the top 10% of the water column. Under stronger wind (> 8 m s-1, and hence larger wave conditions, whitecapping waves provided the dominant source of turbulent kinetic energy over a larger portion of the water column; however, this region extended to the bottom half of the water column for only 7% of the observation period. The model results indicated that phytoplankton concentrations close to the bed were unlikely to be affected by the whitecapping of waves, and that the formation of concentration boundary layers due to benthic grazing was unlikely to be disrupted by whitecapping waves. Furthermore, vertical mixing of suspended sediment was unlikely to be affected by whitecapping waves under the conditions experienced during the 11-day experiment. Instead, the bed stress provided by tidal currents was the dominant source of turbulent kinetic energy over the bottom half of the water column for the majority of the 11-day period.

  6. Wind Turbine Generator Efficiency Based on Powertrain Combination and Annual Power Generation Prediction

    Directory of Open Access Journals (Sweden)

    Dongmyung Kim

    2018-05-01

    Full Text Available Wind turbine generators are eco-friendly generators that produce electric energy using wind energy. In this study, wind turbine generator efficiency is examined using a powertrain combination and annual power generation prediction, by employing an analysis model. Performance testing was conducted in order to analyze the efficiency of a hydraulic pump and a motor, which are key components, and so as to verify the analysis model. The annual wind speed occurrence frequency for the expected installation areas was used to predict the annual power generation of the wind turbine generators. It was found that the parallel combination of the induction motors exhibited a higher efficiency when the wind speed was low and the serial combination showed higher efficiency when wind speed was high. The results of predicting the annual power generation considering the regional characteristics showed that the power generation was the highest when the hydraulic motors were designed in parallel and the induction motors were designed in series.

  7. Low Cost Small Wind Turbine Generators for Developing Countries

    NARCIS (Netherlands)

    Ani, S.O.

    2013-01-01

    Wind energy accounts for an increasing percentage of the energy supplied to the electricity network. Electricity generation from wind is now cheaper than other renewables and almost cost competitive with other conventional sources of electricity generation. However, this impressive growth is largely

  8. Reliability analysis of wind embedded power generation system for ...

    African Journals Online (AJOL)

    This paper presents a method for Reliability Analysis of wind energy embedded in power generation system for Indian scenario. This is done by evaluating the reliability index, loss of load expectation, for the power generation system with and without integration of wind energy sources in the overall electric power system.

  9. Magnetosheath waves under very low solar wind dynamic pressure: Wind/Geotail observations

    Directory of Open Access Journals (Sweden)

    C. J. Farrugia

    2005-06-01

    Full Text Available The expanded bow shock on and around "the day the solar wind almost disappeared" (11 May 1999 allowed the Geotail spacecraft to make a practically uninterrupted 54-h-long magnetosheath pass near dusk (16:30-21:11 magnetic local time at a radial distance of 24 to 30 RE (Earth radii. During most of this period, interplanetary parameters varied gradually and in such a way as to give rise to two extreme magnetosheath structures, one dominated by magnetohydrodynamic (MHD effects and the other by gas dynamic effects. We focus attention on unusual features of electromagnetic ion wave activity in the former magnetosheath state, and compare these features with those in the latter. Magnetic fluctuations in the gas dynamic magnetosheath were dominated by compressional mirror mode waves, and left- and right-hand polarized electromagnetic ion cyclotron (EIC waves transverse to the background field. In contrast, the MHD magnetosheath, lasting for over one day, was devoid of mirror oscillations and permeated instead by EIC waves of weak intensity. The weak wave intensity is related to the prevailing low solar wind dynamic pressures. Left-hand polarized EIC waves were replaced by bursts of right-hand polarized waves, which remained for many hours the only ion wave activity present. This activity occurred when the magnetosheath proton temperature anisotropy (= $T_{p, perp}/T_{p, parallel}{-}1$ became negative. This was because the weakened bow shock exposed the magnetosheath directly to the (negative temperature anisotropy of the solar wind. Unlike the normal case studied in the literature, these right-hand waves were not by-products of left-hand polarized waves but derived their energy source directly from the magnetosheath temperature anisotropy. Brief entries into the

  10. Magnetosheath waves under very low solar wind dynamic pressure: Wind/Geotail observations

    Directory of Open Access Journals (Sweden)

    C. J. Farrugia

    2005-06-01

    Full Text Available The expanded bow shock on and around "the day the solar wind almost disappeared" (11 May 1999 allowed the Geotail spacecraft to make a practically uninterrupted 54-h-long magnetosheath pass near dusk (16:30-21:11 magnetic local time at a radial distance of 24 to 30 RE (Earth radii. During most of this period, interplanetary parameters varied gradually and in such a way as to give rise to two extreme magnetosheath structures, one dominated by magnetohydrodynamic (MHD effects and the other by gas dynamic effects. We focus attention on unusual features of electromagnetic ion wave activity in the former magnetosheath state, and compare these features with those in the latter. Magnetic fluctuations in the gas dynamic magnetosheath were dominated by compressional mirror mode waves, and left- and right-hand polarized electromagnetic ion cyclotron (EIC waves transverse to the background field. In contrast, the MHD magnetosheath, lasting for over one day, was devoid of mirror oscillations and permeated instead by EIC waves of weak intensity. The weak wave intensity is related to the prevailing low solar wind dynamic pressures. Left-hand polarized EIC waves were replaced by bursts of right-hand polarized waves, which remained for many hours the only ion wave activity present. This activity occurred when the magnetosheath proton temperature anisotropy (= became negative. This was because the weakened bow shock exposed the magnetosheath directly to the (negative temperature anisotropy of the solar wind. Unlike the normal case studied in the literature, these right-hand waves were not by-products of left-hand polarized waves but derived their energy source directly from the magnetosheath temperature anisotropy. Brief entries into the low latitude boundary layer (LLBL and duskside magnetosphere occurred under such inflated conditions that the magnetospheric magnetic pressure was insufficient to maintain pressure balance. In these crossings, the inner edge of

  11. Wind power generation and dispatch in competitive power markets

    Science.gov (United States)

    Abreu, Lisias

    Wind energy is currently the fastest growing type of renewable energy. The main motivation is led by more strict emission constraints and higher fuel prices. In addition, recent developments in wind turbine technology and financial incentives have made wind energy technically and economically viable almost anywhere. In restructured power systems, reliable and economical operation of power systems are the two main objectives for the ISO. The ability to control the output of wind turbines is limited and the capacity of a wind farm changes according to wind speeds. Since this type of generation has no production costs, all production is taken by the system. Although, insufficient operational planning of power systems considering wind generation could result in higher system operation costs and off-peak transmission congestions. In addition, a GENCO can participate in short-term power markets in restructured power systems. The goal of a GENCO is to sell energy in such a way that would maximize its profitability. However, due to market price fluctuations and wind forecasting errors, it is essential for the wind GENCO to keep its financial risk at an acceptable level when constituting market bidding strategies. This dissertation discusses assumptions, functions, and methodologies that optimize short-term operations of power systems considering wind energy, and that optimize bidding strategies for wind producers in short-term markets. This dissertation also discusses uncertainties associated with electricity market environment and wind power forecasting that can expose market participants to a significant risk level when managing the tradeoff between profitability and risk.

  12. Assessment of wind energy potential for electricity generation

    African Journals Online (AJOL)

    Wind energy is proposed as an alternative source of electricity to fossil fuel generators .... can be connected to the national grid line to supplement the shortfall that arises during the dry ... systems are environmentally friendly. By generating ...

  13. statistical analysis of wind speed for electrical power generation

    African Journals Online (AJOL)

    HOD

    sites are suitable for the generation of electrical energy. Also, the results ... Nigerian Journal of Technology (NIJOTECH). Vol. 36, No. ... parameter in the wind-power generation system. ..... [3] A. Zaharim, A. M Razali, R. Z Abidin, and K Sopian,.

  14. Effect of fall wind on wind power generation; Furyoku hatsuden ni okeru dashikaze no koka

    Energy Technology Data Exchange (ETDEWEB)

    Nagai, H [Nihon University, Tokyo (Japan)

    1997-11-25

    Wind conditions in Arakawa Town, Niigata Prefecture, were surveyed by anemometers and anemoscopes installed at 3 different points, and the data are analyzed to develop the prediction model for investigating possibility of introduction of wind mills there. Outlined herein is power generated by fall wind by comparing predicted power availability with the actual results. In order to investigate possibility of power generation by fall wind, the wind conditions and power availability are simulated using the observed wind condition data. Predicted wind velocity involves a large error at a point where frequency of prevailing wind direction is high, and direction in which average wind velocity is high coincides with direction in which land is slanted at a high slope. Fall wind occurs locally for geographical reasons. Location of the wind mill must be carefully considered, because it is complex, although potentially gives a larger quantity of power. A wind mill of 400kW can produce power of around 600MWh annually, when it is located at the suited site confirmed by the wind condition analysis results. 6 refs., 5 figs., 6 tabs.

  15. Wind Turbine Power Curve Design for Optimal Power Generation in Wind Farms Considering Wake Effect

    Directory of Open Access Journals (Sweden)

    Jie Tian

    2017-03-01

    Full Text Available In modern wind farms, maximum power point tracking (MPPT is widely implemented. Using the MPPT method, each individual wind turbine is controlled by its pitch angle and tip speed ratio to generate the maximum active power. In a wind farm, the upstream wind turbine may cause power loss to its downstream wind turbines due to the wake effect. According to the wake model, downstream power loss is also determined by the pitch angle and tip speed ratio of the upstream wind turbine. By optimizing the pitch angle and tip speed ratio of each wind turbine, the total active power of the wind farm can be increased. In this paper, the optimal pitch angle and tip speed ratio are selected for each wind turbine by the exhausted search. Considering the estimation error of the wake model, a solution to implement the optimized pitch angle and tip speed ratio is proposed, which is to generate the optimal control curves for each individual wind turbine off-line. In typical wind farms with regular layout, based on the detailed analysis of the influence of pitch angle and tip speed ratio on the total active power of the wind farm by the exhausted search, the optimization is simplified with the reduced computation complexity. By using the optimized control curves, the annual energy production (AEP is increased by 1.03% compared to using the MPPT method in a case-study of a typical eighty-turbine wind farm.

  16. Nonlinear internal gravity waves and their interaction with the mean wind

    International Nuclear Information System (INIS)

    Grimshaw, R.

    1975-01-01

    The interaction of a wave packet of internal gravity waves with the mean wind is investigated, for the case when there is a region of wind shear and hence a critical level. The principal equations are the Doppler-shifted dispersion relation, the equation for conservation of wave action and the mean momentum equation, in which the mean wind is accelerated by a 'radiation stress' tensor, due to the waves. These equations are integrated numerically to study the behaviour of a wave packet approaching a critical level, where the horizontal phase speed matches the mean wind. The results demonstrate the exchange of energy from the waves to the mean wind in the vicinity of the critical level. The interaction between the waves and the mean wind is also studied in the absence of any initial wind shear. (author)

  17. The influence of waves on the offshore wind resource

    Energy Technology Data Exchange (ETDEWEB)

    Lange, B [Risoe National Lab., Roskilde (Denmark); Hoejstrup, J [NEG Micon, Randers (Denmark)

    1999-03-01

    With the growing interest in offshore wind resources, it has become increasingly important to establish and refine models for the interaction between wind and waves in order to obtain accurate models for the sea surface roughness. The simple Charnock relation that has been applied for open sea conditions does not work well in the shallow water near-coastal areas that are important for offshore wind energy. A model for the surface roughness of the sea has been developed based on this concept, using an expression for the Charnock constant as a function of wave age, and then relating the wave `age` to the distance to the nearest upwind coastline. The data used in developing these models originated partly from analysis of data from the Vindeby site, partly from previously published results. The scatter in the data material was considerable and consequently there is a need to test these models further by analysing data from sites exhibiting varying distances to the coast. Results from such analysis of recent data are presented for sites with distances to the coast varying from 10 km to several hundreds of km. The model shows a good agreement also with this data. (au)

  18. On WKB expansions for Alfven waves in the solar wind

    International Nuclear Information System (INIS)

    Hollweg, J.V.

    1990-01-01

    The author reexamines the WKB expansion for toroidal Alfven waves in the solar wind, as described by equations (9) of Heinemann and Olbert (1980). His principal conclusions are as follows: (1) The WKB expansion used by Belcher (1971) and Hollweg (1973) is nonuniformly convergent. (2) Using the method of multiple scales (Nayfeh, 1981), he obtains an expansion which is uniform. (3) The uniform expansion takes into account the small modification to the Alfven wave phase speed due to spatial gradients of the background. (4) Both the uniform and nonuniform expansions reveal that each normal mode has both Elsaesser variables δz + ≠ 0 and δz - ≠ 0. Thus if δz - corresponds to the outgoing mode in a homogeneous background, an observation of δz + ≠ 0 does not necessarily imply the presence of the inward propagating mode, as is commonly assumed. (5) Even at the Alfven critical point (where V = υ A ) he finds that δz + ≠ 0. Thus incompressible MHD turbulence, which requires both δz + ≠ 0 and δz - ≠ 0, can proceed at the Alfven critical point (cf. Roberts, 1989). (6) With very few exceptions, the predictions of these calculations do not agree with recent observations (Marsch and Tu, 1990) of the power spectra of δz + and δz - in the solar wind. Thus the evolution of Alfven waves in the solar wind is governed by dynamics not included in the Heinemann and Olbert equations

  19. Manual for wave generation and analysis

    DEFF Research Database (Denmark)

    Jakobsen, Morten Møller

    This Manual is for the included wave generation and analysis software and graphical user interface. The package is made for Matlab and is meant for educational purposes. The code is free to use under the GNU Public License (GPL). It is still in development and should be considered as such. If you...

  20. Optimization of airborne wind energy generators

    NARCIS (Netherlands)

    Fagiano, L.; Milanese, M.; Piga, D.

    2012-01-01

    This paper presents novel results related to an innovative airborne wind energy technology, named Kitenergy, for the conversion of high-altitude wind energy into electricity. The research activities carried out in the last five years, including theoretical analyses, numerical simulations, and

  1. Aerodynamical noise from wind turbine generators

    International Nuclear Information System (INIS)

    Jakobsen, J.; Andersen, B.

    1993-06-01

    Two extensive measurement series of noise from wind turbines have been made during different modifications of their rotors. One series focused on the influence from the tip shape on the noise, while the other series dealt with the influence from the trailing edge. The experimental layout for the two investigations was identical. The total A-weighted noise from the wind turbine was measured in 1/3 octave bands from 50 Hz to 10 kHz in 1-minute periods simultaneously with wind speed measurements. The microphone was mounted on a hard board on the ground about 40 m directly downwind of the wind turbine, and the wind speed meter was placed at the same distance upwind of the wind turbine 10 m above ground. Regression analysis was made between noise and wind speed in each 1/3 octave band to determine the spectrum at 8 m/s. During the measurements care was taken to avoid influence from background noise, and the influence from machinery noise was minimized and corrected for. Thus the results display the aerodynamic rotor noise from the wind turbines. By use of this measurement technique, the uncertainty has been reduced to 1.5 - 2 dB per 1/3 octave band in the relevant frequency range and to about 1 dB on the total A-weighted levels. (au) (10 refs.)

  2. Design evolution of large wind turbine generators

    Science.gov (United States)

    Spera, D. A.

    1979-01-01

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

  3. Selecting optimum locations for co-located wave and wind energy farms. Part II: A case study

    International Nuclear Information System (INIS)

    Astariz, S.; Iglesias, G.

    2016-01-01

    Highlights: • The benefits of wave and wind combined systems relative to independent farms are analysed. • This purpose is carried out through a case study off the Danish coast. • The power production, power smoothing and shadow effect are analysed. • Hindcast and measured wave and wind data from 2005 to 2015 are used. • Third-generation models of winds and waves (WAsP and SWAN) are used. - Abstract: Combined energy systems present an opportunity to enhance the competitiveness of renewables and overcome other challenges of these novel renewables by realising the synergies between them. Among the different possibilities for combined systems, this work focuses on wave and wind co-located farms with the aim of assessing their benefits relative to standalone wind farms. To this end we estimate the energy production, investigate the power smoothing and shadow effect, and quantify the reduction in downtime achieved by the co-located farm through a case study off the Danish coast – a promising area for co-located farms based on the available resource and other considerations including technical constraints. The analysis is carried out based on hindcast data and observations extending from 2005 to 2015, and by means of state-of-the-art numerical models of the wind and wave fields – WAsP and SWAN, respectively. It is found that the energy yield per unit area with the combined wave-wind farm increases by 3.4% relative to a standalone wind farm, the downtime periods decrease by 58% and the power output variability reduces by 12.5%. Moreover, the capital and operational expenditures (CAPEX and OPEX, respectively) would also be significantly reduced thanks to the synergies realised through the combination of wind and wave power.

  4. SimWIND: A geospatial infrastructure model for optimizing wind power generation and transmission

    International Nuclear Information System (INIS)

    Phillips, Benjamin R.; Middleton, Richard S.

    2012-01-01

    Wind is a clean, enduring energy resource with the capacity to satisfy 20% or more of U.S. electricity demand. Presently, wind potential is limited by a paucity of electrical transmission lines and/or capacity between promising wind resources and primary load centers. We present the model SimWIND to address this shortfall. SimWIND is an integrated optimization model for the geospatial arrangement and cost minimization of wind-power generation–transmission–delivery infrastructure. Given a set of possible wind-farm sites, the model simultaneously determines (1) where and how much power to generate and (2) where to build new transmission infrastructure and with what capacity in order to minimize the cost for delivering a targeted amount of power to load. Costs and routing of transmission lines consider geographic and social constraints as well as electricity losses. We apply our model to the Electric Reliability Council of Texas (ERCOT) Interconnection, considering scenarios that deliver up to 20 GW of new wind power. We show that SimWIND could potentially reduce ERCOT's projected ∼$5B transmission network upgrade line length and associated costs by 50%. These results suggest that SimWIND's coupled generation–transmission–delivery modeling approach could play a critical role in enhancing planning efforts and reducing costs for wind energy integration. - Highlights: ► Wind power is limited by transmission capacity between resources and demands. ► SimWIND is a coupled generation-transmission-delivery model for wind infrastructure. ► The model minimizes costs considering realistic transmission routing and networking. ► We show that SimWIND could save 50% of $5B costs for expanding the Texas grid. ► Results suggest SimWIND may play a critical role in enhancings wind planning efforts.

  5. Ionospheric cusp flows pulsed by solar wind Alfvén waves

    Directory of Open Access Journals (Sweden)

    P. Prikryl

    2002-02-01

    observed delay of the reconnection onset. The compressional fluctuations in solar wind and those generated in the magnetosheath through the interaction between the solar wind Alfvén waves and the bow shock were the source of magnetopause surface waves inducing reconnection.Key words. Interplanetary physics (MHD waves and turbulence – Magnetospheric physics (magnetosphere-ionosphere interactions; solar wind-magnetosphere interactions

  6. Wind Generation on Winnebago Tribal Lands

    Energy Technology Data Exchange (ETDEWEB)

    Multiple

    2009-09-30

    The Winnebago Wind Energy Study evaluated facility-scale, community-scale and commercial-scale wind development on Winnebago Tribal lands in northeastern Nebraska. The Winnebago Tribe of Nebraska has been pursuing wind development in various forms for nearly ten years. Wind monitoring utilizing loaned met towers from NREL took place during two different periods. From April 2001 to April 2002, a 20-meter met tower monitored wind data at the WinnaVegas Casino on the far eastern edge of the Winnebago reservation in Iowa. In late 2006, a 50-meter tower was installed, and subsequently monitored wind data at the WinnaVegas site from late 2006 through late 2008. Significant challenges with the NREL wind monitoring equipment limited the availability of valid data, but based on the available data, average wind speeds between 13.6 – 14.3 miles were indicated, reflecting a 2+/3- wind class. Based on the anticipated cost of energy produced by a WinnaVegas wind turbine, and the utility policies and rates in place at this time, a WinnaVegas wind project did not appear to make economic sense. However, if substantial grant funding were available for energy equipment at the casino site, and if either Woodbury REC backup rates were lower, or NIPCO was willing to pay more for wind power, a WinnaVegas wind project could be feasible. With funding remaining in the DOE-funded project budget,a number of other possible wind project locations on the Winnebago reservation were considered. in early 2009, a NPPD-owned met tower was installed at a site identified in the study pursuant to a verbal agreement with NPPD which provided for power from any ultimately developed project on the Western Winnebago site to be sold to NPPD. Results from the first seven months of wind monitoring at the Western Winnebago site were as expected at just over 7 meters per second at 50-meter tower height, reflecting Class 4 wind speeds, adequate for commercial development. If wind data collected in the remaining

  7. Diaphragmless shock wave generators for industrial applications of shock waves

    Science.gov (United States)

    Hariharan, M. S.; Janardhanraj, S.; Saravanan, S.; Jagadeesh, G.

    2011-06-01

    The prime focus of this study is to design a 50 mm internal diameter diaphragmless shock tube that can be used in an industrial facility for repeated loading of shock waves. The instantaneous rise in pressure and temperature of a medium can be used in a variety of industrial applications. We designed, fabricated and tested three different shock wave generators of which one system employs a highly elastic rubber membrane and the other systems use a fast acting pneumatic valve instead of conventional metal diaphragms. The valve opening speed is obtained with the help of a high speed camera. For shock generation systems with a pneumatic cylinder, it ranges from 0.325 to 1.15 m/s while it is around 8.3 m/s for the rubber membrane. Experiments are conducted using the three diaphragmless systems and the results obtained are analyzed carefully to obtain a relation between the opening speed of the valve and the amount of gas that is actually utilized in the generation of the shock wave for each system. The rubber membrane is not suitable for industrial applications because it needs to be replaced regularly and cannot withstand high driver pressures. The maximum shock Mach number obtained using the new diaphragmless system that uses the pneumatic valve is 2.125 ± 0.2%. This system shows much promise for automation in an industrial environment.

  8. Vertical Wave Impacts on Offshore Wind Turbine Inspection Platforms

    DEFF Research Database (Denmark)

    Bredmose, Henrik; Jacobsen, Niels Gjøl

    2011-01-01

    Breaking wave impacts on a monopile at 20 m depth are computed with a VOF (Volume Of Fluid) method. The impacting waves are generated by the second-order focused wave group technique, to obtain waves that break at the position of the monopile. The subsequent impact from the vertical run-up flow...... on a horizontal inspection platform is computed for five different platform levels. The computational results show details of monopile impact such as slamming pressures from the overturning wave front and the formation of run-up flow. The results show that vertical platform impacts can occur at 20 m water depth....... The dependence of the vertical platform load to the platform level is discussed. Attention is given to the significant downward force that occur after the upward force associated with the vertical impact. The effect of the numerical resolution on the results is assessed. The position of wave overturning is found...

  9. Modeling of wind turbines with doubly fed generator system

    CERN Document Server

    Fortmann, Jens

    2014-01-01

    Jens Fortmann describes the deduction of models for the grid integration of variable speed wind turbines and the reactive power control design of wind plants. The modeling part is intended as background to understand the theory, capabilities and limitations of the generic doubly fed generator and full converter wind turbine models described in the IEC 61400-27-1 and as 2nd generation WECC models that are used as standard library models of wind turbines for grid simulation software. Focus of the reactive power control part is a deduction of the origin and theory behind the reactive current requ

  10. Photovoltaic-wind hybrid autonomous generation systems in Mongolia

    Energy Technology Data Exchange (ETDEWEB)

    Dei, Tsutomu; Ushiyama, Izumi

    2005-01-01

    Two hybrid stand-alone (autonomous) power systems, each with wind and PV generation, were studied as installed at health clinics in semi-desert and mountainous region in Mongolia. Meteorological and system operation parameters, including power output and the consumption of the system, were generally monitored by sophisticated monitoring. However, where wind and solar site information was lacking, justifiable estimates were made. The results show that there is a seasonal complementary relationship between wind and solar irradiation in Tarot Sum. The users understood the necessity of Demand Side Management of isolated wind-PV generation system through technology transfer seminars and actually executed DSM at both sites. (author)

  11. Solar, wind and waves: Natural limits to renewable sources of energy within the Earth system

    Energy Technology Data Exchange (ETDEWEB)

    Kleidon, Axel [Max-Planck-Institute for Biogeochemistry, Jena (Germany)

    2013-07-01

    Renewable sources of energy, such as solar, wind, wave, or hydropower, utilize energy that is continuously generated by natural processes within the Earth system from the planetary forcing. Here we estimate the limits of these natural energy conversions and the extent to which these can be used as renewable energy sources using the laws of thermodynamics. At most, wind power in the order of 1 000 TW (1 TW = 1E12 W) can be derived from the total flux of incoming solar radiation of 175 000 TW, which is consistent with estimates based on observations. Other generation rates that are derived from the kinetic energy of wind are in the order of 10-100 TW. In comparison, the human primary energy demand of about 17 TW constitutes a considerable fraction of these rates. We provide some further analysis on the limits of wind power using a combination of conceptual models, observational data, and numerical simulation models. We find that many current estimates of wind power substantially overestimate the potential of wind power because the effect of kinetic energy extraction on the air flow is neglected. We conclude that the only form of renewable energy that is available in substantial amounts and that is associated with minor climatic impacts is solar power.

  12. On the Use of Coupled Wind, Wave, and Current Fields in the Simulation of Loads on Bottom-Supported Offshore Wind Turbines during Hurricanes: March 2012 - September 2015

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Eungsoo [Univ. of Texas, Austin, TX (United States); Manuel, Lance [Univ. of Texas, Austin, TX (United States); Curcic, Milan [Univ. of Miami, Coral Gables, FL (United States); Chen, Shuyi S. [Univ. of Miami, Coral Gables, FL (United States); Phillips, Caleb [National Renewable Energy Lab. (NREL), Golden, CO (United States); Veers, Paul [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2016-06-01

    In the United States, potential offshore wind plant sites have been identified along the Atlantic seaboard and in the Gulf of Mexico. It is imperative that we define external conditions associated with hurricanes and severe winter storms and consider load cases for which wind turbines may need to be designed. We selected two hurricanes, Ike (2008) and Sandy (2012), and investigated the effect these tropical storms would have on bottom-supported offshore wind turbines that were hypothetically in or close to their path as they made landfall. For realistic turbine loads assessment, it is important that the coupled influences of the changing wind, wave, and current fields are simulated throughout the evolution of the hurricanes. We employed a coupled model--specifically, the University of Miami Coupled Model (UMCM)--that integrates atmospheric, wave, and ocean components to produce needed wind, wave, and current data. The wind data are used to generate appropriate vertical wind profiles and full wind velocity fields including turbulence; the current field over the water column is obtained by interpolated discrete output current data; and short-crested irregular second-order waves are simulated using output directional wave spectra from the coupled model. We studied two monopile-supported offshore wind turbines sited in 20 meters of water in the Gulf of Mexico to estimate loads during Hurricane Ike, and a jacket space-frame platform-supported offshore wind turbine sited in 50 meters of water in the mid-Atlantic region to estimate loads during Hurricane Sandy. In this report we discuss in detail how the simulated hurricane wind, wave, and current output data are used in turbine loads studies. In addition, important characteristics of the external conditions are studied, including the relative importance of swell versus wind seas, aerodynamic versus hydrodynamic forces, current velocity effects, yaw control options for the turbine, hydrodynamic drag versus inertia forces

  13. Heat generation by a wind turbine

    Energy Technology Data Exchange (ETDEWEB)

    Corten, G.P. [ECN Wind, Petten (Netherlands)

    2001-01-01

    It will be shown that an actuator disk operating in wind turbine mode extracts more energy from the fluid than can be transferred into useful energy. At the Lanchester-Betz limit the decrease of the kinetic energy in the wind is converted by 2 /3 into useful power and by 1 /3 into heat. Behind the wind turbine the outer flow and the flow that has passed the actuator disk will mix. In this process momentum is conserved but part of the kinetic energy will dissipate in heat via viscous shear. 7 refs.

  14. Capacity expansion model of wind power generation based on ELCC

    Science.gov (United States)

    Yuan, Bo; Zong, Jin; Wu, Shengyu

    2018-02-01

    Capacity expansion is an indispensable prerequisite for power system planning and construction. A reasonable, efficient and accurate capacity expansion model (CEM) is crucial to power system planning. In most current CEMs, the capacity of wind power generation is considered as boundary conditions instead of decision variables, which may lead to curtailment or over construction of flexible resource, especially at a high renewable energy penetration scenario. This paper proposed a wind power generation capacity value(CV) calculation method based on effective load-carrying capability, and a CEM that co-optimizes wind power generation and conventional power sources. Wind power generation is considered as decision variable in this model, and the model can accurately reflect the uncertainty nature of wind power.

  15. An approach to the conversion of the power generated by an offshore wind power farm connected into seawave power generator

    Energy Technology Data Exchange (ETDEWEB)

    Franzitta, Vicenzo; Messineo, Antonio; Trapanese, Marco

    2011-07-01

    The development of renewable energy systems has been undergoing for the past decades but sea wave's energy resource has been under-utilized. This under-utilization has several reasons: the energy concentration is low in sea waves, extraction of this energy requires leading edge technologies and conversion of the energy into electrical energy is difficult. This study compares two different methods to connect the sea waves' generator to the network and to the offshore wind power farm. The first method consists in a decentralized approach: each generator is connected to the grid through an AC converter. The second method is a partially centralized approach: a rectifier is connected to each generator, all of the generators are then connected together to a common DC bus and power is then converted in AC to be connected to the grid. This study has shown that the partially centralized approach is more reliable and efficient than the decentralized approach.

  16. Predictions of Resuspension of Highway Detention Pond Deposits in Interrain Event Periods due to Wind-Induced Currents and Waves

    DEFF Research Database (Denmark)

    Bentzen, Thomas Ruby; Larsen, Torben; Rasmussen, Michael R.

    2009-01-01

    -shear stress induced by the return flow near the bed and waves both generated by the wind. Wind statistics for 30 years have been applied for prediction of the annual discharged bulk of suspended solids and associated pollutants; fluoranthene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, dibenzo......(a,h)anthracene and indeno(1,2,3-cd)pyrene (PAHs) and the heavy metals of cadmium, chromium, copper, lead, nickel, and zinc. The current and wave-generated bed-shear stresses entail a discharged bulk of pollutants corresponding to approximately 10% of the annual accumulation of pollutants in the present pond due...

  17. The interaction of katabatic winds and mountain waves

    Energy Technology Data Exchange (ETDEWEB)

    Poulos, Gregory Steve [Colorado State Univ., Fort Collins, CO (United States)

    1997-01-01

    The variation in the oft-observed, thermally-forced, nocturnal katabatic winds along the east side of the Rocky Mountains can be explained by either internal variability or interactions with various other forcings. Though generally katabatic flows have been studied as an entity protected from external forcing by strong thermal stratification, this work investigates how drainage winds along the Colorado Front Range interact with, in particular, topographically forced mountain waves. Previous work has shown, based on measurements taken during the Atmospheric Studies in Complex Terrain 1993 field program, that the actual dispersion in katabatic flows is often greater than reflected in models of dispersion. The interaction of these phenomena is complicated and non-linear since the amplitude, wavelength and vertical structure of mountain waves developed by flow over the Rocky Mountain barrier are themselves partly determined by the evolving atmospheric stability in which the drainage flows develop. Perturbations to katabatic flow by mountain waves, relative to their more steady form in quiescent conditions, are found to be caused by both turbulence and dynamic pressure effects. The effect of turbulent interaction is to create changes to katabatic now depth, katabatic flow speed, katabatic jet height and, vertical thermal stratification. The pressure effect is found to primarily influence the variability of a given katabatic now through the evolution of integrated column wave forcing on surface pressure. Variability is found to occur on two scales, on the mesoscale due to meso-gamma scale mountain wave evolution, and on the microscale, due to wave breaking. Since existing parameterizations for the statically stable case are predominantly based on nearly flat terrain atmospheric measurements under idealized or nearly quiescent conditions, it is no surprise that these parameterizations often contribute to errors in prediction, particularly in complex terrain.

  18. Economic Selection of Generators for a Wind Farm

    Directory of Open Access Journals (Sweden)

    Omid Alavi

    2015-09-01

    Full Text Available The selection suitable generator for wind turbines will be done based on technical criteria and priorities of the project. In this paper, a method for determining the type of wind turbine generator with an example is explained. In the paper, for a 10kW wind turbine, two generators have been proposed. The first case is a squirrel-cage asynchronous generator coupled to the turbine through the gearbox and directly connected to three phase output. Other PM generators that are directly coupled to the turbine and it is connected to the grid using the inverter. The results show that according to wind conditions, a 10kW permanent magnet generator is more advantageous in terms of energy production.

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

    Energy Technology Data Exchange (ETDEWEB)

    van Dam, J.; Jager, D.

    2010-02-01

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

  20. Performance characteristics of aerodynamically optimum turbines for wind energy generators

    Science.gov (United States)

    Rohrbach, C.; Worobel, R.

    1975-01-01

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

  1. A KINETIC ALFVEN WAVE AND THE PROTON DISTRIBUTION FUNCTION IN THE FAST SOLAR WIND

    International Nuclear Information System (INIS)

    Li Xing; Lu Quanming; Chen Yao; Li Bo; Xia Lidong

    2010-01-01

    Using one-dimensional test particle simulations, the effect of a kinetic Alfven wave on the velocity distribution function (VDF) of protons in the collisionless solar wind is investigated. We first use linear Vlasov theory to numerically obtain the property of a kinetic Alfven wave (the wave propagates in the direction almost perpendicular to the background magnetic field). We then numerically simulate how the wave will shape the proton VDF. It is found that Landau resonance may be able to generate two components in the initially Maxwellian proton VDF: a tenuous beam component along the direction of the background magnetic field and a core component. The streaming speed of the beam relative to the core proton component is about 1.2-1.3 Alfven speed.

  2. Observations of neutral winds, wind shears, and wave structure during a sporadic-E/QP event

    Directory of Open Access Journals (Sweden)

    M. F. Larsen

    2005-10-01

    Full Text Available The second Sporadic E Experiment over Kyushu (SEEK-2 was carried out on 3 August 2002, during an active sporadic-E event that also showed quasi-periodic (QP echoes. Two rockets were launched into the event from Kagoshima Space Center in southern Japan 15 min apart. Both carried a suite of instruments, but the second rocket also released a trimethyl aluminum (TMA trail to measure the neutral winds and turbulence structure. In a number of earlier measurements in similar conditions, large winds and shears that were either unstable or close to instability were observed in the altitude range where the ionization layer occurred. The SEEK-2 wind measurements showed similar vertical structure, but unlike earlier experiments, there was a significant difference between the up-leg and down-leg wind profiles. In addition, wave or billow-like fluctuations were evident in the up-leg portion of the trail, while the lower portion of the down-leg trail was found to have extremely strong turbulence that led to a rapid break-up of the trail. The large east-west gradient in the winds and the strong turbulence have not been observed before. The wind profiles and shears, as well as the qualitative characteristics of the strong turbulence are presented, along with a discussion of the implications of the dynamical features. Keywords. Ionosphere (Mid-latitude ionosphere; Ionospheric irregularities; Electric field and currents

  3. Market protocols in ERCOT and their effect on wind generation

    International Nuclear Information System (INIS)

    Sioshansi, Ramteen; Hurlbut, David

    2010-01-01

    Integrating wind generation into power systems and wholesale electricity markets presents unique challenges due to the characteristics of wind power, including its limited dispatchability, variability in generation, difficulty in forecasting resource availability, and the geographic location of wind resources. Texas has had to deal with many of these issues beginning in 2002 when it restructured its electricity industry and introduced aggressive renewable portfolio standards that helped spur major investments in wind generation. In this paper we discuss the issues that have arisen in designing market protocols that take account of these special characteristics of wind generation and survey the regulatory and market rules that have been developed in Texas. We discuss the perverse incentives some of the rules gave wind generators to overschedule generation in order to receive balancing energy payments, and steps that have been taken to mitigate those incentive effects. Finally, we discuss more recent steps taken by the market operator and regulators to ensure transmission capacity is available for new wind generators that are expected to come online in the future.

  4. Arrangement for matching a wind rotor to an electrical generator

    Energy Technology Data Exchange (ETDEWEB)

    Beusse, H

    1978-04-06

    The invention concerns an arrangement for matching a wind power machine to an electrical generator, which feeds a consumer network. According to the invention first generator using the shaft horsepower of the wind power machine feeds an electric water, which is coupled to a second generator, whose power is taken to the consumer network. The output signal of a computer which has the annemometer feeding into it controls the excitation of the motor at sufficient wind speed, so that the speed of rotation of the second generator is practically constant, and a spted regulator takes excess energy via a controlled rectifier (thyristor) to a shunt circuit of the motor, if the wind power exceeds the load taken from the output of the second generator. As an extension of the arrangement according to the invention it is proposed to arrange a Diesel engine in the shaft of the second generator, which can be controlled at constant speed by the control device, so that it takes over the missing output if the wind power is less than the load at the generator output. Apart from this, it is proposed that the loading of the wind rotor should be controlled by the control device so that it only comes in if the wind rotor has reached a stable working point after accelerating on no load.

  5. Method and apparatus for generating acoustic waves

    International Nuclear Information System (INIS)

    Rao, G.V.; Gopal, R.

    1982-01-01

    A portable source of acoustic waves comprises a sample of iron-nickel alloy including an austenite phase cooled to become martensite, and a wave guide to transmit the acoustic waves. The source is applied to the pressure boundary region of a pressurized water reactor to simulate an actual metal flaw and test the calibration of the monitoring and surveillance system. With at most 29.7% nickel in the sample, the source provides acoustic emission due to ductile deformation, and with at least 30% nickel the acoustic emission is characteristic of a brittle deformation. Thus, the monitoring and surveillance system can be tested in either or both situations. In the prior art, synthetic waveform signals were used for such calibration but found not suitable for on-line simulation of the surveillance system. This invention provides an improved system in that it generates true acoustic signals. (author)

  6. The Parametric Decay Instability of Alfvén Waves in Turbulent Plasmas and the Applications in the Solar Wind

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Mijie; Xiao, Chijie; Wang, Xiaogang [State Key Laboratory of Nuclear Physics and Technology, Fusion Simulation Center, School of Physics, Peking University, Beijing 100871 (China); Li, Hui, E-mail: cjxiao@pku.edu.cn [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2017-06-10

    We perform three-dimensional ideal magnetohydrodynamic (MHD) simulations to study the parametric decay instability (PDI) of Alfvén waves in turbulent plasmas and explore its possible applications in the solar wind. We find that, over a broad range of parameters in background turbulence amplitudes, the PDI of an Alfvén wave with various amplitudes can still occur, though its growth rate in turbulent plasmas tends to be lower than both the theoretical linear theory prediction and that in the non-turbulent situations. Spatial–temporal FFT analyses of density fluctuations produced by the PDI match well with the dispersion relation of the slow MHD waves. This result may provide an explanation of the generation mechanism of slow waves in the solar wind observed at 1 au. It further highlights the need to explore the effects of density variations in modifying the turbulence properties as well as in heating the solar wind plasmas.

  7. Effect of Second-Order and Fully Nonlinear Wave Kinematics on a Tension-Leg-Platform Wind Turbine in Extreme Wave Conditions: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Robertson, Amy N [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Jonkman, Jason [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Pegalajar-Jurado, Antonio [Technical University of Denmark; Borg, Michael [Technical University of Denmark; Bredmose, Henrik [Technical University of Denmark

    2017-08-02

    In this study, we assess the impact of different wave kinematics models on the dynamic response of a tension-leg-platform wind turbine. Aero-hydro-elastic simulations of the floating wind turbine are carried out employing linear, second-order, and fully nonlinear kinematics using the Morison equation for the hydrodynamic forcing. The wave kinematics are computed from either theoretical or measured signals of free-surface elevation. The numerical results from each model are compared to results from wave basin tests on a scaled prototype. The comparison shows that sub and superharmonic responses can be introduced by second-order and fully nonlinear wave kinematics. The response at the wave frequency range is better reproduced when kinematics are generated from the measured surface elevation. In the future, the numerical response may be further improved by replacing the global, constant damping coefficients in the model by a more detailed, customizable definition of the user-defined numerical damping.

  8. Effect of Second-Order and Fully Nonlinear Wave Kinematics on a Tension-Leg-Platform Wind Turbine in Extreme Wave Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Robertson, Amy N [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Jonkman, Jason [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Pegalajar-Jurado, Antonio [Technical University of Denmark; Borg, Michael [Technical University of Denmark; Bredmose, Henrik [Technical University of Denmark

    2017-06-03

    In this study, we assess the impact of different wave kinematics models on the dynamic response of a tension-leg-platform wind turbine. Aero-hydro-elastic simulations of the floating wind turbine are carried out employing linear, second-order, and fully nonlinear kinematics using the Morison equation for the hydrodynamic forcing. The wave kinematics are computed from either theoretical or measured signals of free-surface elevation. The numerical results from each model are compared to results from wave basin tests on a scaled prototype. The comparison shows that sub and superharmonic responses can be introduced by second-order and fully nonlinear wave kinematics. The response at the wave frequency range is better reproduced when kinematics are generated from the measured surface elevation. In the future, the numerical response may be further improved by replacing the global, constant damping coefficients in the model by a more detailed, customizable definition of the user-defined numerical damping.

  9. Simulations of large winds and wind shears induced by gravity wave breaking in the mesosphere and lower thermosphere (MLT) region

    OpenAIRE

    X. Liu; X. Liu; J. Xu; H.-L. Liu; J. Yue; W. Yuan

    2014-01-01

    Using a fully nonlinear two-dimensional (2-D) numerical model, we simulated gravity waves (GWs) breaking and their contributions to the formation of large winds and wind shears in the mesosphere and lower thermosphere (MLT). An eddy diffusion coefficient is used in the 2-D numerical model to parameterize realistic turbulent mixing. Our study shows that the momentum deposited by breaking GWs accelerates the mean wind. The resultant large background wind increases the GW's app...

  10. Performance evaluation of stand alone hybrid PV-wind generator

    International Nuclear Information System (INIS)

    Nasir, M. N. M.; Saharuddin, N. Z.; Sulaima, M. F.; Jali, Mohd Hafiz; Bukhari, W. M.; Bohari, Z. H.; Yahaya, M. S.

    2015-01-01

    This paper presents the performance evaluation of standalone hybrid system on Photovoltaic (PV)-Wind generator at Faculty of Electrical Engineering (FKE), UTeM. The hybrid PV-Wind in UTeM system is combining wind turbine system with the solar system and the energy capacity of this hybrid system can generate up to charge the battery and supply the LED street lighting load. The purpose of this project is to evaluate the performance of PV-Wind hybrid generator. Solar radiation meter has been used to measure the solar radiation and anemometer has been used to measure the wind speed. The effectiveness of the PV-Wind system is based on the various data that has been collected and compared between them. The result shows that hybrid system has greater reliability. Based on the solar result, the correlation coefficient shows strong relationship between the two variables of radiation and current. The reading output current followed by fluctuate of solar radiation. However, the correlation coefficient is shows moderate relationship between the two variables of wind speed and voltage. Hence, the wind turbine system in FKE show does not operate consistently to produce energy source for this hybrid system compare to PV system. When the wind system does not fully operate due to inconsistent energy source, the other system which is PV will operate and supply the load for equilibrate the extra load demand

  11. Performance evaluation of stand alone hybrid PV-wind generator

    Science.gov (United States)

    Nasir, M. N. M.; Saharuddin, N. Z.; Sulaima, M. F.; Jali, Mohd Hafiz; Bukhari, W. M.; Bohari, Z. H.; Yahaya, M. S.

    2015-05-01

    This paper presents the performance evaluation of standalone hybrid system on Photovoltaic (PV)-Wind generator at Faculty of Electrical Engineering (FKE), UTeM. The hybrid PV-Wind in UTeM system is combining wind turbine system with the solar system and the energy capacity of this hybrid system can generate up to charge the battery and supply the LED street lighting load. The purpose of this project is to evaluate the performance of PV-Wind hybrid generator. Solar radiation meter has been used to measure the solar radiation and anemometer has been used to measure the wind speed. The effectiveness of the PV-Wind system is based on the various data that has been collected and compared between them. The result shows that hybrid system has greater reliability. Based on the solar result, the correlation coefficient shows strong relationship between the two variables of radiation and current. The reading output current followed by fluctuate of solar radiation. However, the correlation coefficient is shows moderate relationship between the two variables of wind speed and voltage. Hence, the wind turbine system in FKE show does not operate consistently to produce energy source for this hybrid system compare to PV system. When the wind system does not fully operate due to inconsistent energy source, the other system which is PV will operate and supply the load for equilibrate the extra load demand.

  12. Performance evaluation of stand alone hybrid PV-wind generator

    Energy Technology Data Exchange (ETDEWEB)

    Nasir, M. N. M.; Saharuddin, N. Z.; Sulaima, M. F.; Jali, Mohd Hafiz; Bukhari, W. M.; Bohari, Z. H. [Faculty of Electrical Engineering, Universiti Teknikal Malaysia Melaka (UTeM), Hang Tuah Jaya, 76100 Melaka (Malaysia); Yahaya, M. S. [Faculty of Engineering Technology, Universiti Teknikal Malaysia Melaka (UTeM), Hang Tuah Jaya, 76100 Melaka (Malaysia)

    2015-05-15

    This paper presents the performance evaluation of standalone hybrid system on Photovoltaic (PV)-Wind generator at Faculty of Electrical Engineering (FKE), UTeM. The hybrid PV-Wind in UTeM system is combining wind turbine system with the solar system and the energy capacity of this hybrid system can generate up to charge the battery and supply the LED street lighting load. The purpose of this project is to evaluate the performance of PV-Wind hybrid generator. Solar radiation meter has been used to measure the solar radiation and anemometer has been used to measure the wind speed. The effectiveness of the PV-Wind system is based on the various data that has been collected and compared between them. The result shows that hybrid system has greater reliability. Based on the solar result, the correlation coefficient shows strong relationship between the two variables of radiation and current. The reading output current followed by fluctuate of solar radiation. However, the correlation coefficient is shows moderate relationship between the two variables of wind speed and voltage. Hence, the wind turbine system in FKE show does not operate consistently to produce energy source for this hybrid system compare to PV system. When the wind system does not fully operate due to inconsistent energy source, the other system which is PV will operate and supply the load for equilibrate the extra load demand.

  13. The U.S. Navy's Global Wind-Wave Models: An Investigation into Sources of Errors in Low-Frequency Energy Predictions

    National Research Council Canada - National Science Library

    Rogers, W

    2002-01-01

    This report describes an investigation to determine the relative importance of various sources of error in the two global-scale models of wind-generated surface waves used operationally by the U.S. Navy...

  14. Wind power: cost effective generation for the 1990s

    Energy Technology Data Exchange (ETDEWEB)

    Pedersen, T [Vestas Wind Systems A/S (Denmark)

    1989-01-01

    Wind power plants have been installed all over the world, notably in California and Denmark. Commercially available wind turbines today are rated from 50 KW to 1 MW with emphasis on the 1 MW range. As the fuel is ''free'' generating costs are identical to the capital, operation and maintenance costs of the plant. An estimate of the unit price of wind power generated electricity in Denmark is comparable to that generated by a coal fired plant. The main environmental impacts of a wind farm are considered. These are visual impact, noise emission, use of (agricultural) space and the impact on wildlife, mainly birds. Finally the installation of a wind farm and its connection to the grid are described. (3 figures, 1 table). (UK)

  15. Modeling and Parameter Estimation of a Small Wind Generation System

    Directory of Open Access Journals (Sweden)

    Carlos A. Ramírez Gómez

    2013-11-01

    Full Text Available The modeling and parameter estimation of a small wind generation system is presented in this paper. The system consists of a wind turbine, a permanent magnet synchronous generator, a three phase rectifier, and a direct current load. In order to estimate the parameters wind speed data are registered in a weather station located in the Fraternidad Campus at ITM. Wind speed data were applied to a reference model programed with PSIM software. From that simulation, variables were registered to estimate the parameters. The wind generation system model together with the estimated parameters is an excellent representation of the detailed model, but the estimated model offers a higher flexibility than the programed model in PSIM software.

  16. Power Electronics for the Next Generation Wind Turbine System

    DEFF Research Database (Denmark)

    Ma, Ke

    generation unit, are becoming crucial in the wind turbine system. The objective of this project is to study the power electronics technology used for the next generation wind turbines. Some emerging challenges as well as potentials like the cost of energy and reliability are going to be addressed. First...... conversion is pushed to multi-MW level with high power density requirement. It has also been revealed that thermal stress in the power semiconductors is closely related to many determining factors in the wind power application like the reliability, cost, power density, etc. therefore it is an important......The wind power generation has been steadily growing both for the total installed capacity and for the individual turbine size. Due to much more significant impacts to the power grid, the power electronics, which can change the behavior of wind turbines from an unregulated power source to an active...

  17. A methodology to generate statistically dependent wind speed scenarios

    Energy Technology Data Exchange (ETDEWEB)

    Morales, J.M.; Conejo, A.J. [Department of Electrical Engineering, Univ. Castilla - La Mancha, Campus Universitario s/n, 13071 Ciudad Real (Spain); Minguez, R. [Environmental Hydraulics Institute ' ' IH Cantabria' ' , Univ. Cantabria, Avenida de los Castros s/n, 39005 Santander (Spain)

    2010-03-15

    Wind power - a renewable energy source increasingly attractive from an economic viewpoint - constitutes an electricity production alternative of growing relevance in current electric energy systems. However, wind power is an intermittent source that cannot be dispatched at the will of the producer. Modeling wind power production requires characterizing wind speed at the sites where the wind farms are located. The wind speed at a particular location can be described through a stochastic process that is spatially correlated with the stochastic processes describing wind speeds at other locations. This paper provides a methodology to characterize the stochastic processes pertaining to wind speed at different geographical locations via scenarios. Each one of these scenarios embodies time dependencies and is spatially dependent of the scenarios describing other wind stochastic processes. The scenarios generated by the proposed methodology are intended to be used within stochastic programming decision models to make informed decisions pertaining to wind power production. The methodology proposed is accurate in reproducing wind speed historical series as well as computationally efficient. A comprehensive case study is used to illustrate the capabilities of the proposed methodology. Appropriate conclusions are finally drawn. (author)

  18. A methodology to generate statistically dependent wind speed scenarios

    International Nuclear Information System (INIS)

    Morales, J.M.; Minguez, R.; Conejo, A.J.

    2010-01-01

    Wind power - a renewable energy source increasingly attractive from an economic viewpoint - constitutes an electricity production alternative of growing relevance in current electric energy systems. However, wind power is an intermittent source that cannot be dispatched at the will of the producer. Modeling wind power production requires characterizing wind speed at the sites where the wind farms are located. The wind speed at a particular location can be described through a stochastic process that is spatially correlated with the stochastic processes describing wind speeds at other locations. This paper provides a methodology to characterize the stochastic processes pertaining to wind speed at different geographical locations via scenarios. Each one of these scenarios embodies time dependencies and is spatially dependent of the scenarios describing other wind stochastic processes. The scenarios generated by the proposed methodology are intended to be used within stochastic programming decision models to make informed decisions pertaining to wind power production. The methodology proposed is accurate in reproducing wind speed historical series as well as computationally efficient. A comprehensive case study is used to illustrate the capabilities of the proposed methodology. Appropriate conclusions are finally drawn.

  19. Power generation from wind turbines in a solar chimney

    Energy Technology Data Exchange (ETDEWEB)

    Foote, Tudor [Graduate Student, Department of Mechanical Engineering and Materials Science, Washington University in St. Louis, Jolley Hall, Campus Box 1185, One Brookings Drive, St. Louis, Missouri, 63130 (United States); Agarwal, Ramesh K. [William Palm Professor, Department of Mechanical Engineering and Materials Science, Washington University in St. Louis, Jolley Hall, Campus Box 1185, One Brookings Drive, St. Louis, Missouri, 63130 (United States)

    2013-07-01

    Recent studies have shown that shrouded wind turbines can generate greater power compared to bare turbines. A solar chimney generates an upward draft of wind inside a tower and a shroud around the wind turbine. There are numerous empty silos on farms in the U.S. that can be converted to solar chimneys with minor modifications at modest cost. The objective of this study is to determine the potential of these silos/chimneys for generating wind power. The study is conducted through analytical/computational approach by employing the commercial Computational Fluid Dynamics (CFD) software. Computations are performed for five different geometric configurations consisting of a turbine, a cylindrical silo, and/or a venturi and/or a diffuser using the dimensions of typical silos and assuming Class 3 wind velocity. The incompressible Navier-Stokes equations with the Boussinesq approximation and a two equation realizable {kappa}-{epsilon} model are employed in the calculations, and the turbine is modeled as an actuator disk. The power coefficient (Cp) and generated power are calculated for the five cases. Consistent with recent literature, it was found that the silos with diffusers increase the Cp beyond Betz’s limit significantly and thus the generated power. It should be noted that Cp is calculated by normalizing it by the turbine area swept by the wind. This study shows the potential of using abandoned silos in the mid-west and other parts of the country for localized wind power generation.

  20. 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

  1. Some answers to power generation lie blowing in the wind

    Energy Technology Data Exchange (ETDEWEB)

    1975-10-02

    An assessment of wind power generation schemes by the Energy Technology Support Unit is reported. The capital cost of large, efficient windmills should be around 100--200 Pounds per installed kW and an optimum size for a single wind rotor would be 1 MW.

  2. Power Electronics for the Next Generation Wind Turbine System

    DEFF Research Database (Denmark)

    Ma, Ke

    This book presents recent studies on the power electronics used for the next generation wind turbine system. Some criteria and tools for evaluating and improving the critical performances of the wind power converters have been proposed and established. The book addresses some emerging problems...

  3. The environmental interactions of tidal and wave energy generation devices

    International Nuclear Information System (INIS)

    Frid, Chris; Andonegi, Eider; Depestele, Jochen; Judd, Adrian; Rihan, Dominic; Rogers, Stuart I.; Kenchington, Ellen

    2012-01-01

    Global energy demand continues to grow and tidal and wave energy generation devices can provide a significant source of renewable energy. Technological developments in offshore engineering and the rising cost of traditional energy means that offshore energy resources will be economic in the next few years. While there is now a growing body of data on the ecological impacts of offshore wind farms, the scientific basis on which to make informed decisions about the environmental effects of other offshore energy developments is lacking. Tidal barrages have the potential to cause significant ecological impacts particularly on bird feeding areas when they are constructed at coastal estuaries or bays. Offshore tidal stream energy and wave energy collectors offer the scope for developments at varying scales. They also have the potential to alter habitats. A diversity of designs exist, including floating, mid-water column and seabed mounted devices, with a variety of moving-part configurations resulting in a unique complex of potential environmental effects for each device type, which are discussed to the extent possible. - Highlights: ► We review the environmental impacts of tidal barrages and fences, tidal stream farms and wave energy capture devices. ► Impacts on habitats, species and the water column, and effects of noise and electromagnetic fields are considered. ► Tidal barrages can cause significant impacts on bird feeding areas when constructed at coastal estuaries or bays. ► Wave energy collectors can alter water column and sea bed habitats locally and over large distances.

  4. Influence of winding construction on starter-generator thermal processes

    Science.gov (United States)

    Grachev, P. Yu; Bazarov, A. A.; Tabachinskiy, A. S.

    2018-01-01

    Dynamic processes in starter-generators features high winding are overcurrent. It can lead to insulation overheating and fault operation mode. For hybrid and electric vehicles, new high efficiency construction of induction machines windings is proposed. Stator thermal processes need be considered in the most difficult operation modes. The article describes construction features of new compact stator windings, electromagnetic and thermal models of processes in stator windings and explains the influence of innovative construction on thermal processes. Models are based on finite element method.

  5. Future wave and wind projections for United States and United-States-affiliated Pacific Islands

    Science.gov (United States)

    Storlazzi, Curt D.; Shope, James B.; Erikson, Li H.; Hegermiller, Christine A.; Barnard, Patrick L.

    2015-01-01

    Changes in future wave climates in the tropical Pacific Ocean from global climate change are not well understood. Spatially and temporally varying waves dominate coastal morphology and ecosystem structure of the islands throughout the tropical Pacific. Waves also impact coastal infrastructure, natural and cultural resources, and coastal-related economic activities of the islands. Wave heights, periods, and directions were forecast through the year 2100 using wind parameter outputs from four atmosphere-ocean global climate models from the Coupled Model Inter-Comparison Project, Phase 5, for Representative Concentration Pathways (RCP) scenarios 4.5 and 8.5 that correspond to moderately mitigated and unmitigated greenhouse gas emissions, respectively. Wind fields from the global climate models were used to drive a global WAVEWATCH-III wave model and generate hourly time-series of bulk wave parameters for 25 islands in the mid to western tropical Pacific for the years 1976–2005 (historical), 2026–2045 (mid-century projection), and 2085–2100 (end-of-century projection). Although the results show some spatial heterogeneity, overall the December-February extreme significant wave heights, defined as the mean of the top 5 percent of significant wave height time-series data modeled within a specific period, increase from present to mid-century and then decrease toward the end of the century; June-August extreme wave heights increase throughout the century within the Central region of the study area; and September-November wave heights decrease strongly throughout the 21st century, displaying the largest and most widespread decreases of any season. Peak wave periods increase east of the International Date Line during the December-February and June-August seasons under RCP4.5. Under the RCP8.5 scenario, wave periods decrease west of the International Date Line during December-February but increase in the eastern half of the study area. Otherwise, wave periods decrease

  6. Operating of Small Wind Power Plants with Induction Generators

    Directory of Open Access Journals (Sweden)

    Jakub Nevrala

    2008-01-01

    Full Text Available This paper describes different systems of small wind power plants with induction generators used in the Czech Republic. Problems of wind power plants running with induction generators are solved within partial target of the research project MSM 6198910007. For small wind power plants is used induction motor as a generator. Parameters of the name plate of motor must be resolved for generator running on measuring base. These generators are running as a separately working generators or generators connected to the power grid. Methods of control these systems as a separately working, directly connecting to power grid, control by frequency converter and wiring by synchronous cascade are confronted on the measuring base too.

  7. Power Maximization Control of Variable Speed Wind Generation System Using Permanent Magnet Synchronous Generator

    Science.gov (United States)

    Morimoto, Shigeo; Nakamura, Tomohiko; Takeda, Yoji

    This paper proposes the sensorless output power maximization control of the wind generation system. A permanent magnet synchronous generator (PMSG) is used as a variable speed generator in the proposed system. The generator torque is suitably controlled according to the generator speed and thus the power from a wind turbine settles down on the maximum power point by the proposed MPPT control method, where the information of wind velocity is not required. Moreover, the maximum available generated power is obtained by the optimum current vector control. The current vector of PMSG is optimally controlled according to the generator speed and the required torque in order to minimize the losses of PMSG considering the voltage and current constraints. The proposed wind power generation system can be achieved without mechanical sensors such as a wind velocity detector and a position sensor. Several experimental results show the effectiveness of the proposed control method.

  8. Wind Power Generation in India: Evolution, Trends and Prospects

    Directory of Open Access Journals (Sweden)

    M.F. Khan

    2013-10-01

    Full Text Available In the present context of shrinking conventional resources coupled with environmental perils, the wind power offers an attractive alternative. Wind power generation in India started way back in early 1980s with the installation of experimental wind turbines in western and southern states of Gujarat and Tamil Nadu. For first two decades of its existence until about 2000 the progress was slow but steady. In last one decade Indian wind electricity sector has grown at very rapid pace which has promoted the country to the fifth position as largest wind electric power generator and the third largest market in the world. The galvanization of wind sector has been achieved through some aggressive policy mechanisms and persistent support by government organizations such as MNRE and C-WET. This paper articulates the journey of Indian wind program right since its inception to the present trends and developments as well as the future prospects. Keywords: mnre, c-wet, renewable energy, wind power, wind turbines.

  9. Fully Coupled Three-Dimensional Dynamic Response of a Tension-Leg Platform Floating Wind Turbine in Waves and Wind

    DEFF Research Database (Denmark)

    Kumari Ramachandran, Gireesh Kumar Vasanta; Bredmose, Henrik; Sørensen, Jens Nørkær

    2014-01-01

    , which is a consequence of the wave-induced rotor dynamics. Loads and coupled responses are predicted for a set of load cases with different wave headings. Further, an advanced aero-elastic code, Flex5, is extended for the TLP wind turbine configuration and the response comparison with the simpler model......A dynamic model for a tension-leg platform (TLP) floating offshore wind turbine is proposed. The model includes three-dimensional wind and wave loads and the associated structural response. The total system is formulated using 17 degrees of freedom (DOF), 6 for the platform motions and 11...... for the wind turbine. Three-dimensional hydrodynamic loads have been formulated using a frequency-and direction-dependent spectrum. While wave loads are computed from the wave kinematics using Morison's equation, the aerodynamic loads are modeled by means of unsteady blade-element-momentum (BEM) theory...

  10. Short circuit signatures from different wind turbine generator types

    DEFF Research Database (Denmark)

    Martinez, Jorge; Kjær, Philip C.; Rodriguez, Pedro

    2011-01-01

    Modern wind power plants are required and designed to ride through faults in the network, subjected to the fault clearance and following grid code demands. Beside voltage support during faults, the wind turbine fault current contribution is important to establish the correct settings for the relay...... of the protections. The following wind turbine generator during faults have been studied: (i) induction generator, (ii) induction generator with variable rotor resistance (iii) converter-fed rotor (often referred to as DFIG) and (iv) full scale converter. To make a clear comparison and performance analysis during...... faults, and the consequent effects on substation protections, the aforementioned configurations have been simulated using PSCAD/EMTDC, with the same power plant configuration, electrical grid and generator data. Additionally, a comparison of these wind turbine technologies with a conventional power plant...

  11. Minimisation of Generation Variability of a Group of Wind Plants

    Directory of Open Access Journals (Sweden)

    Dubravko Sabolić

    2017-09-01

    Full Text Available Minimisation of variability of energy delivered from a group of wind plants into the power system using portfolio theory approach was studied. One of the assumptions of that theory is Gaussian distribution of the sample, which is not satisfied in case of wind generation. Therefore, optimisation of a “portfolio” of plants with different goal functions was studied. It was supposed that a decision on distribution of a fixed amount of generation capacity to be installed among a set of geographical locations with known wind statistics is to be made with minimised variability of generation as a goal. In that way the statistical cancellation of variability would be used in the best possible manner. This article is a brief report on results of such an investigation. An example of nine locations in Croatia was used. These locations’ wind statistics are known from historic generation data.

  12. Hybrid system power generation'wind-photovoltaic' connected to the ...

    African Journals Online (AJOL)

    Hybrid system power generation'wind-photovoltaic' connected to the ... from Hybrid System, power delivered to or from grid and phase voltage of the inverter leg. ... Renewable Energy, Electrical Network 220 kV, Hybrid System, Solar, MPPT.

  13. Risk assessment of electric generation systems with high wind penetration

    International Nuclear Information System (INIS)

    Salgado Duarte, Yorlandys; Castillo Serpa, Alfredo M. del

    2017-01-01

    The research evaluates the risk function of an Electric Generation System (SGE) with high wind power penetration using the Sequential Monte Carlo Simulation (SMCS) method, which allows calculating indicators that characterize the performance of the SGE with expected average values. The research uses a Markov model of two states or four states according to the characteristics of the generator to simulate the instantaneous capacity. The primary sources of each conventional generator are assumed to be always available; however, wind power depends on the wind behavior in each analyzed region. In this research, the Chronological Series and Weibull models are used to model the wind behavior, and the analyzes are performed in the IEEE-RTS system. The work shows that the behavior of the probabilistic indicators used to analyze the static capacity of the SGE is determined by the model used to simulate the stochastic of the generators and by the primary energy source. (author)

  14. Superconducting generators for wind turbines: design considerations

    DEFF Research Database (Denmark)

    Mijatovic, Nenad; Abrahamsen, Asger Bech; Træholt, Chresten

    2010-01-01

    The harmonic content of high temperature superconductors (HTS) field winding in air-core high temperature superconducting synchronous machine (HTS SM) has been addressed in order to investigate tendency of HTS SM towards mechanical oscillation and additional loss caused by higher flux harmonic...

  15. The production of wind-generated electricity

    International Nuclear Information System (INIS)

    2013-11-01

    After some key data on installed wind power and its evolution in the World (notably in China and in the USA), in European countries and in France, an overview of the sector economic evolution in France in terms of jobs in different fields (fabrication, electricity production, studies and installations), this publication comments the various benefits of wind energy and its necessary framework for a sane development. Strengths are discussed: a local and clean energy source, a predictable and manageable energy source, an increasing competitiveness. Issues to be considered are also discussed: control of acoustic and landscape impacts, protection of biodiversity, management of interactions with military, meteorological and civil aviation radars, a necessary more steady and coherent regulation. After a discussion of the possibilities offered by small wind energy installations (between 1 and 36 kW), actions undertaken by the ADEME are overviewed. A conclusion outlines the role of wind energy on the supply-demand balance in the French power system, its contribution to the reduction of greenhouse gas emissions, the positive environmental impact, the importance of societal appropriation, and the importance of developing this sector while keeping on reducing consumptions

  16. Optimal prediction intervals of wind power generation

    DEFF Research Database (Denmark)

    Wan, Can; Wu, Zhao; Pinson, Pierre

    2014-01-01

    direct optimization of both the coverage probability and sharpness to ensure the quality. The proposed method does not involve the statistical inference or distribution assumption of forecasting errors needed in most existing methods. Case studies using real wind farm data from Australia have been...

  17. Fluctuations of offshore wind generation: Statistical modelling

    DEFF Research Database (Denmark)

    Pinson, Pierre; Christensen, Lasse E.A.; Madsen, Henrik

    2007-01-01

    The magnitude of power fluctuations at large offshore wind farms has a significant impact on the control and management strategies of their power output. If focusing on the minute scale, one observes successive periods with smaller and larger power fluctuations. It seems that different regimes yi...

  18. Wind Turbine Contingency Control Through Generator De-Rating

    Science.gov (United States)

    Frost, Susan; Goebel, Kai; Balas, Mark

    2013-01-01

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

  19. Simulated wind-generated inertial oscillations compared to current measurements in the northern North Sea

    Science.gov (United States)

    Bruserud, Kjersti; Haver, Sverre; Myrhaug, Dag

    2018-04-01

    Measured current speed data show that episodes of wind-generated inertial oscillations dominate the current conditions in parts of the northern North Sea. In order to acquire current data of sufficient duration for robust estimation of joint metocean design conditions, such as wind, waves, and currents, a simple model for episodes of wind-generated inertial oscillations is adapted for the northern North Sea. The model is validated with and compared against measured current data at one location in the northern North Sea and found to reproduce the measured maximum current speed in each episode with considerable accuracy. The comparison is further improved when a small general background current is added to the simulated maximum current speeds. Extreme values of measured and simulated current speed are estimated and found to compare well. To assess the robustness of the model and the sensitivity of current conditions from location to location, the validated model is applied at three other locations in the northern North Sea. In general, the simulated maximum current speeds are smaller than the measured, suggesting that wind-generated inertial oscillations are not as prominent at these locations and that other current conditions may be governing. Further analysis of the simulated current speed and joint distribution of wind, waves, and currents for design of offshore structures will be presented in a separate paper.

  20. Wind Velocity and Position Sensor-less Operation for PMSG Wind Generator

    Science.gov (United States)

    Senjyu, Tomonobu; Tamaki, Satoshi; Urasaki, Naomitsu; Uezato, Katsumi; Funabashi, Toshihisa; Fujita, Hideki

    Electric power generation using non-conventional sources is receiving considerable attention throughout the world. Wind energy is one of the available non-conventional energy sources. Electrical power generation using wind energy is possible in two ways, viz. constant speed operation and variable speed operation using power electronic converters. Variable speed power generation is attractive, because maximum electric power can be generated at all wind velocities. However, this system requires a rotor speed sensor, for vector control purpose, which increases the cost of the system. To alleviate the need of rotor speed sensor in vector control, we propose a new sensor-less control of PMSG (Permanent Magnet Synchronous Generator) based on the flux linkage. We can estimate the rotor position using the estimated flux linkage. We use a first-order lag compensator to obtain the flux linkage. Furthermore‚we estimate wind velocity and rotation speed using a observer. The effectiveness of the proposed method is demonstrated thorough simulation results.

  1. Model-based control of a ballast-stabilized floating wind turbine exposed to wind and waves

    Energy Technology Data Exchange (ETDEWEB)

    Christiansen, Soeren

    2013-01-15

    The wind turbine is a commercial product which is competing against other sources of energy, such as coal and gas. This competition drives a constant development to reduce costs and improve efficiency in order to reduce the total cost of the energy. The latest offshore development is the floating wind turbine, for water depths beyond 50 meters where winds are stronger and less turbulent. A floating wind turbine is subject to not only aerodynamics and wind induced loads, but also to hydrodynamics and wave induced loads. In contrast to a bottom fixed wind turbine, the floating structure, the hydrodynamics and the loads change the dynamic behavior of a floating wind turbine. Consequently, conventional wind turbine control cause instabilities on floating wind turbines. This work addresses the control of a floating spar buoy wind turbine, and focuses on the impact of the additional platform dynamics. A time varying control model is presented based on the wind speed and wave frequency. Estimates of the wind speed and wave frequency are used as scheduling variables in a gain scheduled linear quadratic controller to improve the electrical power production while reducing fatigue. To address the problem of negative damped fore-aft tower motion, additional control loops are suggested which stabilize the response of the onshore controller and reduce the impact of the wave induced loads. This research is then extended to model predictive control, to further address wave disturbances. In the context of control engineering, the dynamics and disturbances of a floating wind turbine have been identified and modeled. The objectives of maximizing the production of electrical power and minimizing fatigue have been reached by using advanced methods of estimation and control. (Author)

  2. ION HEATING IN INHOMOGENEOUS EXPANDING SOLAR WIND PLASMA: THE ROLE OF PARALLEL AND OBLIQUE ION-CYCLOTRON WAVES

    International Nuclear Information System (INIS)

    Ozak, N.; Ofman, L.; Viñas, A.-F.

    2015-01-01

    Remote sensing observations of coronal holes show that heavy ions are hotter than protons and their temperature is anisotropic. In-situ observations of fast solar wind streams provide direct evidence for turbulent Alfvén wave spectrum, left-hand polarized ion-cyclotron waves, and He ++ - proton drift in the solar wind plasma, which can produce temperature anisotropies by resonant absorption and perpendicular heating of the ions. Furthermore, the solar wind is expected to be inhomogeneous on decreasing scales approaching the Sun. We study the heating of solar wind ions in inhomogeneous plasma with a 2.5D hybrid code. We include the expansion of the solar wind in an inhomogeneous plasma background, combined with the effects of a turbulent wave spectrum of Alfvénic fluctuations and initial ion-proton drifts. We study the influence of these effects on the perpendicular ion heating and cooling and on the spectrum of the magnetic fluctuations in the inhomogeneous background wind. We find that inhomogeneities in the plasma lead to enhanced heating compared to the homogenous solar wind, and the generation of significant power of oblique waves in the solar wind plasma. The cooling effect due to the expansion is not significant for super-Alfvénic drifts, and is diminished further when we include an inhomogeneous background density. We reproduce the ion temperature anisotropy seen in observations and previous models, which is present regardless of the perpendicular cooling due to solar wind expansion. We conclude that small scale inhomogeneities in the inner heliosphere can significantly affect resonant wave ion heating

  3. FEM Simulation of Small Wind Power Generating System Using PMSG

    Science.gov (United States)

    Kesamaru, Katsumi; Ohno, Yoshihiro; Sonoda, Daisuke

    The paper describes a new approach to simulate the small wind power generating systems using PMSG, in which the output is connected to constant resistive load, such as heaters, through the rectifier and the dc chopper. The dynamics of the wind power generating system is presented, and it is shown by simulation results that this approach is useful for system dynamics, such as starting phenomena.

  4. Modeling and Simulation of Generator Side Converter of Doubly Fed Induction Generator-Based Wind Power Generation System

    DEFF Research Database (Denmark)

    Guo, Yougui; Zeng, Ping; Blaabjerg, Frede

    2010-01-01

    A real wind power generation system is given in this paper. SVM control strategy and vector control is applied for generator side converter and doubly fed induction generator respectively. First the mathematical models of the wind turbine rotor, drive train, generator side converter are described...

  5. Exploration of dispatch model integrating wind generators and electric vehicles

    International Nuclear Information System (INIS)

    Haque, A.N.M.M.; Ibn Saif, A.U.N.; Nguyen, P.H.; Torbaghan, S.S.

    2016-01-01

    Highlights: • A novel business model for the BRPs is analyzed. • Imbalance cost of wind generation is considered in the UC-ED model. • Smart charging of EVs is included into the UC-ED problem to mitigate the imbalance cost. • Effects of smart charging on generation cost, CO 2 emissions and total network load are assessed. - Abstract: In recent years, the share of renewable energy sources (RES) in the electricity generation mix has been expanding rapidly. However, limited predictability of the RES poses challenges for traditional scheduling and dispatching mechanisms based on unit commitment (UC) and economic dispatch (ED). This paper presents an advanced UC-ED model to incorporate wind generators as RES-based units alongside conventional centralized generators. In the proposed UC-ED model, an imbalance cost is introduced reflecting the wind generation uncertainty along with the marginal generation cost. The proposed UC-ED model aims to utilize the flexibility of fleets of plug-in electric vehicles (PEVs) to optimally compensate for the wind generation uncertainty. A case study with 15 conventional units and 3 wind farms along with a fixed-sized PEV fleet demonstrates that shifting of PEV fleets charging at times of high wind availability realizes generation cost savings. Nevertheless, the operational cost saving incurred by controlled charging appears to diminish when dispatched wind energy becomes considerably larger than the charging energy of PEV fleets. Further analysis of the results reveals that the effectiveness of PEV control strategy in terms of CO 2 emission reduction is strongly coupled with generation mix and the proposed control strategy is favored in cases where less pollutant-based plants like nuclear and hydro power are profoundly dominant.

  6. Different Models for Forecasting Wind Power Generation: Case Study

    Directory of Open Access Journals (Sweden)

    David Barbosa de Alencar

    2017-11-01

    Full Text Available Generation of electric energy through wind turbines is one of the practically inexhaustible alternatives of generation. It is considered a source of clean energy, but still needs a lot of research for the development of science and technologies that ensures uniformity in generation, providing a greater participation of this source in the energy matrix, since the wind presents abrupt variations in speed, density and other important variables. In wind-based electrical systems, it is essential to predict at least one day in advance the future values of wind behavior, in order to evaluate the availability of energy for the next period, which is relevant information in the dispatch of the generating units and in the control of the electrical system. This paper develops ultra-short, short, medium and long-term prediction models of wind speed, based on computational intelligence techniques, using artificial neural network models, Autoregressive Integrated Moving Average (ARIMA and hybrid models including forecasting using wavelets. For the application of the methodology, the meteorological variables of the database of the national organization system of environmental data (SONDA, Petrolina station, from 1 January 2004 to 31 March 2017, were used. A comparison among results by different used approaches is also done and it is also predicted the possibility of power and energy generation using a certain kind of wind generator.

  7. Environmental Impact Assessment of Wind Generators in the Czech Republic

    Directory of Open Access Journals (Sweden)

    Vladimír Lapčík

    2008-11-01

    Full Text Available The article summarizes author´s experience with environmental impact assessment in branch of wind generators. The introductorypart of paper describes legislative obligations of the Czech Republic in frame of fulfilling the European Union´s limits in branch ofrenewable energy resources utilization. Next part of paper deals with analysis of impacts of wind generators on the environment.The final part of paper deals with experience with implementation of the environmental impact assessment process (pursuant to the ActNo. 100/2001 Coll. in the field of wind power in the Czech Republic.

  8. Effects of distributing wind energy generation over Europe

    Energy Technology Data Exchange (ETDEWEB)

    Giebel, G [Risoe National Lab., Wind Energy and Atmospheric Physics Dept., Roskilde (Denmark)

    1999-03-01

    Using data from 60 meteorological stations distributed all over Europe in conjunction with the National Grid Model (NGM) from the Rutherford Appleton Laboratory, the effects of the large-scale distribution of wind energy generation are studied. In some regions of Europe, wind energy already covers a significant proportion of the electricity demand. But the intermittence of the wind resource is always a limiting factor when penetration levels are high. Studies for single countries have shown that distributing the generation over a large area reduces the variability of the output and hence makes wind energy more appealing to utilities, since the stability requirement of the network are easier to fulfil. The data are analysed in terms of absolute highs and lows, temporal and spatial correlations. To assess the financial benefits, the NGM is used to evaluate the match of electricity demand and generation as well as the possibel savings of fossil fuel in an electricity grid incorporating various capacities of wind energy generation. To assess the value of wind energy on a trans-national scale, the European plant mix is modelled, and the NGM is used to simulate the scheduling of these plants in the presence of different penetrations of wind energy. (au) EU-JOULE-3. 11 refs.

  9. Shear Wave Generation by Decoupled and Partially Coupled Explosions

    National Research Council Canada - National Science Library

    Stevens, Jeffry L; Xu, Heming; Baker, G. E

    2008-01-01

    The objective of this project is to investigate the sources of shear wave generation by decoupled and partially coupled explosions, and the differences in shear wave generation between tamped and decoupled explosions...

  10. Evaluating potentials for future generation off-shore wind-power outside Norway

    Science.gov (United States)

    Benestad, R. E.; Haugen, J.; Haakenstad, H.

    2012-12-01

    With todays critical need of renewable energy sources, it is naturally to look towards wind power. With the long coast of Norway, there is a large potential for wind farms offshore Norway. Although there are more challenges with offshore wind energy installations compared to wind farms on land, the offshore wind is generally higher, and there is also higher persistence of wind speed values in the power generating classes. I planning offshore wind farms, there is a need of evaluation of the wind resources, the wind climatology and possible future changes. In this aspect, we use data from regional climate model runs performed in the European ENSEMBLE-project (van der Linden and J.F.B. Mitchell, 2009). In spite of increased reliability in RCMs in the recent years, the simulations still suffer from systematic model errors, therefore the data has to be corrected before using them in wind resource analyses. In correcting the wind speeds from the RCMs, we will use wind speeds from a Norwegian high resolution wind- and wave- archive, NORA10 (Reistad et al 2010), to do quantile mapping (Themeβl et. al. 2012). The quantile mapping is performed individually for each regional simulation driven by ERA40-reanalysis from the ENSEMBLE-project corrected against NORA10. The same calibration is then used to the belonging regional climate scenario. The calibration is done for each grid cell in the domain and for each day of the year centered in a +/-15 day window to make an empirical cumulative density function for each day of the year. The quantile mapping of the scenarios provide us with a new wind speed data set for the future, more correct compared to the raw ENSEMBLE scenarios. References: Reistad M., Ø. Breivik, H. Haakenstad, O. J. Aarnes, B. R. Furevik and J-R Bidlo, 2010, A high-resolution hindcast of wind and waves for The North Sea, The Norwegian Sea and The Barents Sea. J. Geophys. Res., 116. doi:10.1029/2010JC006402. Themessl M. J., A. Gobiet and A. Leuprecht, 2012

  11. Final Report for Project: Impacts of stratification and non-equilibrium winds and waves on hub-height winds

    Energy Technology Data Exchange (ETDEWEB)

    Patton, Edward G. [Univ. Corporation for Atmospheric Research, Boulder, CO (United States)

    2015-07-14

    This project used a combination of turbulence-resolving large-eddy simulations, single-column modeling (where turbulence is parameterized), and currently available observations to improve, assess, and develop a parameterization of the impact of non-equilibrium wave states and stratification on the buoy-observed winds to establish reliable wind data at the turbine hub-height level. Analysis of turbulence-resolving simulations and observations illuminates the non-linear coupling between the atmosphere and the undulating sea surface. This analysis guides modification of existing boundary layer parameterizations to include wave influences for upward extrapolation of surface-based observations through the turbine layer. Our surface roughness modifications account for the interaction between stratification and the effects of swell’s amplitude and wavelength as well as swell’s relative motion with respect to the mean wind direction. The single-column version of the open source Weather and Research Forecasting (WRF) model (Skamarock et al., 2008) serves as our platform to test our proposed planetary boundary layer parameterization modifications that account for wave effects on marine atmospheric boundary layer flows. WRF has been widely adopted for wind resource analysis and forecasting. The single column version is particularly suitable to development, analysis, and testing of new boundary layer parameterizations. We utilize WRF’s single-column version to verify and validate our proposed modifications to the Mellor-Yamada-Nakanishi-Niino (MYNN) boundary layer parameterization (Nakanishi and Niino, 2004). We explore the implications of our modifications for two-way coupling between WRF and wave models (e.g.,Wavewatch III). The newly implemented parameterization accounting for marine atmospheric boundary layer-wave coupling is then tested in three-dimensional WRF simulations at grid sizes near 1 km. These simulations identify the behavior of simulated winds at the

  12. Renewable energy and sustainable communities: Alaska's wind generator experience†

    Directory of Open Access Journals (Sweden)

    R. Steven Konkel

    2013-08-01

    Full Text Available Background . In 1984, the Alaska Department of Commerce and Economic Development (DCED issued the State's first inventory/economic assessment of wind generators, documenting installed wind generator capacity and the economics of replacing diesel-fuel-generated electricity. Alaska's wind generation capacity had grown from hundreds of installed kilowatts to over 15.3 megawatts (MW by January 2012. Method . This article reviews data and conclusions presented in “Alaska's Wind Energy Systems; Inventory and Economic Assessment” (1. (Alaska Department of Commerce and Economic Development, S. Konkel, 1984. It provides a foundation and baseline for understanding the development of this renewable energy source. Results . Today's technologies have evolved at an astonishing pace; a typical generator in an Alaska wind farm now is likely rated at 1.5-MW capacity, compared to the single-kilowatt (kW machines present in 1984. Installed capacity has mushroomed, illustrated by Unalakleet's 600-kW wind farm dwarfing the original three 10-kW machines included in the 1984 inventory. Kodiak Electric had three 1.5-MW turbines installed at Pillar Mountain in 2009, with three additional turbines of 4.5-MW capacity installed in 2012. Utilities now actively plan for wind generation and compete for state funding. Discussion . State of Alaska energy policy provides the context for energy project decision-making. Substantial renewable energy fund (REF awards – $202,000,000 to date for 227 REF projects in the first 5 cycles of funding – along with numerous energy conservation programs – are now in place. Increasing investment in wind is driven by multiple factors. Stakeholders have interests both in public policy and meeting private investment objectives. Wind generator investors should consider project economics and potential impacts of energy decisions on human health. Specifically this article considers: a. changing environmental conditions in remote Alaska

  13. Renewable energy and sustainable communities: Alaska's wind generator experience.

    Science.gov (United States)

    Konkel, R Steven

    2013-01-01

    In 1984, the Alaska Department of Commerce and Economic Development (DCED) issued the State's first inventory/economic assessment of wind generators, documenting installed wind generator capacity and the economics of replacing diesel-fuel-generated electricity. Alaska's wind generation capacity had grown from hundreds of installed kilowatts to over 15.3 megawatts (MW) by January 2012. This article reviews data and conclusions presented in "Alaska's Wind Energy Systems; Inventory and Economic Assessment" (1). (Alaska Department of Commerce and Economic Development, S. Konkel, 1984). It provides a foundation and baseline for understanding the development of this renewable energy source. Today's technologies have evolved at an astonishing pace; a typical generator in an Alaska wind farm now is likely rated at 1.5-MW capacity, compared to the single-kilowatt (kW) machines present in 1984. Installed capacity has mushroomed, illustrated by Unalakleet's 600-kW wind farm dwarfing the original three 10-kW machines included in the 1984 inventory. Kodiak Electric had three 1.5-MW turbines installed at Pillar Mountain in 2009, with three additional turbines of 4.5-MW capacity installed in 2012. Utilities now actively plan for wind generation and compete for state funding. State of Alaska energy policy provides the context for energy project decision-making. Substantial renewable energy fund (REF) awards--$202,000,000 to date for 227 REF projects in the first 5 cycles of funding--along with numerous energy conservation programs--are now in place. Increasing investment in wind is driven by multiple factors. Stakeholders have interests both in public policy and meeting private investment objectives. Wind generator investors should consider project economics and potential impacts of energy decisions on human health. Specifically this article considers: changing environmental conditions in remote Alaska villages, impacts associated with climate change on human health, progress in

  14. Renewable energy and sustainable communities: Alaska's wind generator experience†

    Science.gov (United States)

    Konkel, R. Steven

    2013-01-01

    Background In 1984, the Alaska Department of Commerce and Economic Development (DCED) issued the State's first inventory/economic assessment of wind generators, documenting installed wind generator capacity and the economics of replacing diesel-fuel-generated electricity. Alaska's wind generation capacity had grown from hundreds of installed kilowatts to over 15.3 megawatts (MW) by January 2012. Method This article reviews data and conclusions presented in “Alaska's Wind Energy Systems; Inventory and Economic Assessment” (1). (Alaska Department of Commerce and Economic Development, S. Konkel, 1984). It provides a foundation and baseline for understanding the development of this renewable energy source. Results Today's technologies have evolved at an astonishing pace; a typical generator in an Alaska wind farm now is likely rated at 1.5-MW capacity, compared to the single-kilowatt (kW) machines present in 1984. Installed capacity has mushroomed, illustrated by Unalakleet's 600-kW wind farm dwarfing the original three 10-kW machines included in the 1984 inventory. Kodiak Electric had three 1.5-MW turbines installed at Pillar Mountain in 2009, with three additional turbines of 4.5-MW capacity installed in 2012. Utilities now actively plan for wind generation and compete for state funding. Discussion State of Alaska energy policy provides the context for energy project decision-making. Substantial renewable energy fund (REF) awards – $202,000,000 to date for 227 REF projects in the first 5 cycles of funding – along with numerous energy conservation programs – are now in place. Increasing investment in wind is driven by multiple factors. Stakeholders have interests both in public policy and meeting private investment objectives. Wind generator investors should consider project economics and potential impacts of energy decisions on human health. Specifically this article considers:changing environmental conditions in remote Alaska villages,impacts associated

  15. Modified Grid-Connected CSI for Hybrid PV/Wind Power Generation System

    Directory of Open Access Journals (Sweden)

    D. Amorndechaphon

    2012-01-01

    Full Text Available The principle of a power conditioning unit for hybrid PV/wind power generation system is proposed. The proposed power conditioner is based on the current source inverter (CSI topology. All energy sources are connected in parallel with a DC-bus through the modified wave-shaping circuits. To achieve the unity power factor at the utility grid, the DC-link current can be controlled via the wave-shaping circuits with the sinusoidal PWM scheme. In this work, the carrier-based PWM scheme is also proposed to minimize the utility current THD. The power rating of the proposed system can be increased by connecting more PV/wind modules through their wave-shaping circuits in parallel with the other modules. The details of the operating principles, the system configurations, and the design considerations are described. The effectiveness of the proposed CSI is demonstrated by simulation results.

  16. Optimizing Wind And Hydropower Generation Within Realistic Reservoir Operating Policy

    Science.gov (United States)

    Magee, T. M.; Clement, M. A.; Zagona, E. A.

    2012-12-01

    Previous studies have evaluated the benefits of utilizing the flexibility of hydropower systems to balance the variability and uncertainty of wind generation. However, previous hydropower and wind coordination studies have simplified non-power constraints on reservoir systems. For example, some studies have only included hydropower constraints on minimum and maximum storage volumes and minimum and maximum plant discharges. The methodology presented here utilizes the pre-emptive linear goal programming optimization solver in RiverWare to model hydropower operations with a set of prioritized policy constraints and objectives based on realistic policies that govern the operation of actual hydropower systems, including licensing constraints, environmental constraints, water management and power objectives. This approach accounts for the fact that not all policy constraints are of equal importance. For example target environmental flow levels may not be satisfied if it would require violating license minimum or maximum storages (pool elevations), but environmental flow constraints will be satisfied before optimizing power generation. Additionally, this work not only models the economic value of energy from the combined hydropower and wind system, it also captures the economic value of ancillary services provided by the hydropower resources. It is recognized that the increased variability and uncertainty inherent with increased wind penetration levels requires an increase in ancillary services. In regions with liberalized markets for ancillary services, a significant portion of hydropower revenue can result from providing ancillary services. Thus, ancillary services should be accounted for when determining the total value of a hydropower system integrated with wind generation. This research shows that the end value of integrated hydropower and wind generation is dependent on a number of factors that can vary by location. Wind factors include wind penetration level

  17. Ocean wave generation by collapsing ice shelves

    Science.gov (United States)

    Macayeal, D. R.; Bassis, J. N.; Okal, E. A.; Aster, R. C.; Cathles, L. M.

    2008-12-01

    The 28-29 February, 2008, break-up of the Wilkins Ice Shelf, Antarctica, exemplifies the now-familiar, yet largely unexplained pattern of explosive ice-shelf break-up. While environmental warming is a likely ultimate cause of explosive break-up, several key aspects of their short-term behavior need to be explained: (1) The abrupt, near-simultaneous onset of iceberg calving across long spans of the ice front margin; (2) High outward drift velocity (about 0.3 m/s) of a leading phalanx of tabular icebergs that originate from the seaward edge of the intact ice shelf prior to break-up; (3) Rapid coverage of the ocean surface in the wake of this leading phalanx by small, capsized and dismembered tabular icebergs; (4) Extremely large gravitational potential energy release rates, e.g., up to 3 × 1010 W; (5) Lack of proximal iceberg-calving triggers that control the timing of break-up onset and that maintain the high break-up calving rates through to the conclusion of the event. Motivated by seismic records obtained from icebergs and the Ross Ice Shelf that show hundreds of micro- tsunamis emanating from near the ice shelf front, we re-examine the basic dynamic features of ice- shelf/ocean-wave interaction and, in particular, examine the possibility that collapsing ice shelves themselves are a source of waves that stimulate the disintegration process. We propose that ice-shelf generated surface-gravity waves associated with initial calving at an arbitrary seed location produce stress perturbations capable of triggering the onset of calving on the entire ice front. Waves generated by parting detachment rifts, iceberg capsize and break-up act next to stimulate an inverted submarine landslide (ice- slide) process, where gravitational potential energy released by upward movement of buoyant ice is radiated as surface gravity waves in the wake of the advancing phalanx of tabular icebergs. We conclude by describing how field research and remote sensing can be used to test the

  18. Generators for gearless wind energy converters

    Energy Technology Data Exchange (ETDEWEB)

    Grauers, A. [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Electric Power Engineering

    1996-12-01

    This paper discusses some design alternatives for directly driven generators, and one specific generator type is investigated for a wide range of rated power. First, the specification for a directly driven generator is presented, then different design alternatives are discussed. A radial-flux permanent magnet generator for frequency converter connection has been chosen for a more detailed investigation. The design, optimization and performance of that generator type are presented. Generators from 30 kW to 3 MW are designed and compared with conventional four-pole generators with gear. It is found that a directly driven generator can be more efficient than a conventional generator and gear and have a rather small diameter and a low active weight. 8 refs, 7 figs, 2 tabs

  19. Electricity generating system. [Wind/diesel/flywheel system

    Energy Technology Data Exchange (ETDEWEB)

    Moody, R.L.

    1992-02-05

    An electricity generating system is described which includes a water tank with electric heating elements connected to the water cooling system of a diesel engine which is heated by excess output of the system. Power in excess of that required by a load which is generated by a wind turbine driven generator runs up a flywheel and further excess is absorbed in the tank. A fan associated with a radiator connected to the tank may be operated to dissipate further excess power. When the load requirements exceed the output of the generators linked to the wind turbine and the flywheel the engine operates a synchronous alternator. (author).

  20. Control of Permanent Magnet Synchronous Generator for large wind turbines

    DEFF Research Database (Denmark)

    Busca, Cristian; Stan, Ana-Irina; Stanciu, Tiberiu

    2010-01-01

    Direct Torque Control (DTC) and Field Oriented Control (FOC) are the most dominant control strategies used in generators for wind turbines. In this paper both control methods were implemented on a Permanent Magnet Synchronous Generator (PMSG). The variable speed wind turbine with full scale power...... converter topology was chosen for design. Parameters from a 2 MW wind turbine were used for system modeling. All the components of the wind turbine system (WTS), except the DC-link and the grid site converter were implemented in MATLAB/Simulink. The pitch controller was used to limit the output power...... produced by the turbine. DTC and FOC strategies, using SVM were used to control the generator rotor speed. The performance of the two control strategies were compared after different tests have been carried out....

  1. Comparison of Simulations and Offshore Measurement Data of a Combined Floating Wind and Wave Energy Demonstration Platform

    DEFF Research Database (Denmark)

    Yde, Anders; Larsen, Torben J.; Hansen, Anders Melchior

    2015-01-01

    In this paper, results from comparisons of simulations and measured offshore data from a floating combined wind and wave energy conversion system are presented. The numerical model of the platform is based on the aeroelastic code, HAWC2, developed by DTU Wind Energy, which is coupled with a special...... external system that reads the output generated directly by the wave analysis software WAMIT. The main focus of the comparison is on the statistical trends of the platform motion, mooring loads, and turbine loads in measurements and simulations during different operational conditions. Finally, challenges...

  2. Design Loads on Platforms on Offshore wind Turbine Foundations with Respect to Vertical Wave Run-up

    DEFF Research Database (Denmark)

    Damsgaard, Mathilde L.; Gravesen, Helge; Andersen, Thomas Lykke

    2007-01-01

    reduction in the loads by up to 75%. Furthermore it is indicated, that the fact that offshore wind turbines often are placed on limited water depths thereby increasing the amount of (nearly) breaking waves, seems to increase the run-up height and thereby the pressures on the structure.......Experiences have shown that the vertical run-up generated by waves meeting the offshore wind turbine foundations, can result in rather vigorous loads on appurtenances and platform structures. This study aims to provide a qualitative method of determining run-up height and the following loads...

  3. Observations of wind and waves in the central Bay of Bengal during ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Time-series wind and wave measurements were carried out onboard INS ... relation for gross estimation of effective depth within which the sound energy is generally trapped during its ..... and wave climate; (USA: Pergamon, Elsevier Science).

  4. Determining the impact of wind on system costs via the temporal patterns of load and wind generation

    International Nuclear Information System (INIS)

    Davis, Clay D.; Gotham, Douglas J.; Preckel, Paul V.; Liu, Andrew L.

    2013-01-01

    Ambitious targets have been set for expanding electricity generation from renewable sources, including wind. Expanding wind power impacts needs for other electricity generating resources. As states plan for increasing levels of wind generation in their portfolio of generation resources it is important to consider how this intermittent resource impacts the need for other generation resources. A case study for Indiana estimates the value of wind capacity and demonstrates how to optimize its level and the levels of other generation resources. Changes are driven by temporal patterns of wind power output and load. System wide impacts are calculated for energy, capacity, and costs under multiple wind expansion scenarios which highlight the geographic characteristics of a systems portfolio of wind generation. The impacts of carbon prices, as proposed in the Bingaman Bill, are considered. Finally, calculations showing the effect increasing levels of wind generation will have on end use Indiana retail rates are included. - Highlights: • We estimate the value of wind capacity. • We determine wind generation's impact on the optimal mix of non-wind generation. • Optimal levels of wind and non-wind generation are determined. • We consider the impact of a carbon price on the optimal mix of resources. • The impact of additional wind capacity on Indiana residential rates is calculated

  5. Emergy-based sustainability evaluation of wind power generation systems

    International Nuclear Information System (INIS)

    Yang, Jin; Chen, Bin

    2016-01-01

    Highlights: • Emergy is used to quantify the sustainability level of wind farms. • A GHG-based indicator is incorporated into emergetic accounting. • Possible pathways to achieve sustainable wind farm management are analyzed. - Abstract: With large-scale commercialization of wind technology, one must investigate economical and sustainable wind resource utilization. In this paper, emergy analysis is used to quantify the environmental pressure, renewability, economic efficiency, and sustainability of a typical wind power system, considering the lifetime stages from extraction and processing of raw materials and resources to the final product (electricity) via material transportation, construction and operation. Possible pathways to achieve sustainable management of wind energy supply chain were also analyzed based on scenario analysis. Results show that wind power is a promising means of substituting traditional fossil fuel-based power generation systems, with the lowest transformity of 4.49 × 10"4 sej/J, smaller environmental loading ratio of 5.84, and lower greenhouse gas emission intensity of 0.56 kg/kWh. To shed light on potential pathways to achieve sustainable and low-carbon wind energy supply chain management and make informed choices, a sensitivity analysis was done by establishing scenarios from the perspectives of material recycling and technical development. Results suggest that using new materials of lower energy intensity or recycled materials in upstream wind turbine manufacturing and construction materials are the most effective measures.

  6. Neural network based control of Doubly Fed Induction Generator in wind power generation

    Science.gov (United States)

    Barbade, Swati A.; Kasliwal, Prabha

    2012-07-01

    To complement the other types of pollution-free generation wind energy is a viable option. Previously wind turbines were operated at constant speed. The evolution of technology related to wind systems industry leaded to the development of a generation of variable speed wind turbines that present many advantages compared to the fixed speed wind turbines. In this paper the phasor model of DFIG is used. This paper presents a study of a doubly fed induction generator driven by a wind turbine connected to the grid, and controlled by artificial neural network ANN controller. The behaviour of the system is shown with PI control, and then as controlled by ANN. The effectiveness of the artificial neural network controller is compared to that of a PI controller. The SIMULINK/MATLAB simulation for Doubly Fed Induction Generator and corresponding results and waveforms are displayed.

  7. Conceptual survey of Generators and Power Electronics for Wind Turbines

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, L.H.; Helle, L.; Blaabjerg, F.; Ritchie, E.; Munk-Nielsen, S.; Bindner, H.; Soerensen, P.; Bak-Jensen, B.

    2001-12-01

    This report presents a survey on generator concepts and power electronic concepts for wind turbines. The report is aimed as a tool for decision-makers and development people with respect to wind turbine manufactures, utilities, and independent system operators as well as manufactures of generators and power electronics. The survey is focused on the electric development of wind turbines and it yields an overview on: State of the art on generators and power electronics; future concepts and technologies within generators and power electronics; market needs in the shape of requirements to the grid connection, and; consistent system solutions, plus an evaluation of these seen in the prospect of market needs. This survey on of generator and power electronic concepts was carried out in co-operation between Aalborg University and Risoe National Laboratory in the scope of the research programme Electric Design and Control. (au)

  8. Assessment of the Joint Development Potential of Wave and Wind Energy in the South China Sea

    Directory of Open Access Journals (Sweden)

    Yong Wan

    2018-02-01

    Full Text Available The South China Sea is a major shipping hub between the West Pacific and Indian Oceans. In this region, the demand for energy is enormous, both for residents’ daily lives and for economic development. Wave energy and wind energy are two major clean and low-cost ocean sources of renewable energy. The reasonable development and utilization of these energy sources can provide a stable energy supply for coastal cities and remote islands of China. Before wave energy and wind energy development, however, we must assess the potential of each of these sources. Based on high-resolution and high-accuracy wave field data and wind field data obtained by ERA-Interim reanalysis for the recent 38-year period from 1979–2016, the joint development potential of wave energy and wind energy was assessed in detail for offshore and nearshore areas in the South China Sea. Based on potential installed capacity, the results revealed three promising areas for the joint development of nearshore wave energy and wind energy, including the Taiwan Strait, Luzon Strait and the sea southeast of the Indo-China Peninsula. For these three dominant areas (key stations, the directionality of wave energy and wind energy propagation were good in various seasons; the dominant wave conditions and the dominant wind conditions were the same, which is advantageous for the joint development of wave and wind energy. Existing well-known wave energy converters (WECs are not suitable for wave energy development in the areas of interest. Therefore, we must consider the distributions of wave conditions and develop more suitable WECs for these areas. The economic and environmental benefits of the joint development of wave and wind energy are high in these promising areas. The results described in this paper can provide references for the joint development of wave and wind energy in the South China Sea.

  9. Generating gravity waves with matter and electromagnetic waves

    International Nuclear Information System (INIS)

    Barrabes, C.; Hogan, P A.

    2008-01-01

    If a homogeneous plane lightlike shell collides head on with a homogeneous plane electromagnetic shock wave having a step-function profile then no backscattered gravitational waves are produced. We demonstrate, by explicit calculation, that if the matter is accompanied by a homogeneous plane electromagnetic shock wave with a step-function profile then backscattered gravitational waves appear after the collision

  10. On-Line Generation of 3D-Waves

    DEFF Research Database (Denmark)

    Frigaard, Peter

    1992-01-01

    The paper describes the technique of filtering white noise for on-line generation of 3D-waves on a small computer in the laboratory. The wave generation package is implemented and tested in the 3D-wave basin at the University of Aalborg.......The paper describes the technique of filtering white noise for on-line generation of 3D-waves on a small computer in the laboratory. The wave generation package is implemented and tested in the 3D-wave basin at the University of Aalborg....

  11. Multi-objective Generation Expansion Planning for Integrating Largescale Wind Generation

    DEFF Research Database (Denmark)

    Zhang, Chunyu; Ding, Yi; Kang, Chongqing

    2013-01-01

    Due to the growth of energy consumption, the extensive use of conventional fossil fuels from the exhaustible resources and the environmental concerns, high penetration of renewable energy resources is considerably observed worldwide. Wind power generation is holding the first rank in terms...... of utilization and importance. In the last decade, the growth rate of the global installed wind capacity has been about 30% per annum. Denmark, Germany, and Spain are the first few countries generating 20% of their electricity from wind turbines....

  12. Harnessing Alternative Energy Sources to Enhance the Design of a Wave Generator

    Science.gov (United States)

    Bravo, A.

    2017-12-01

    Wave energy has the power to replace a non-renewable source of electricity for a home near the ocean. I built a small-scale wave generator capable of producing approximately 5 volts of electricity. The generator is an array of 16 small generators, each consisting of 200 feet of copper wire, 12 magnets, and a buoy. I tested my design in the Pacific Ocean and was able to power a string of lights I had attached to the generator. While the waves in the ocean moved my buoys, my design was powered by the vertical motion of the waves. My generator was hit with significant horizontal wave motion, and I realized I wasn't taking advantage of that direction of motion. To make my generator produce more electricity, I experimented with capturing the energy of the horizontal motion of water and incorporated that into my generator design. My generator, installed in the ocean, is also exposed to sun and wind, and I am exploring the potential of solar and wind energy collection in my design to increase the electricity output. Once I have maximized my electricity output, I would like to explore scaling up my design.

  13. Synchrophasor Applications for Wind Power Generation

    Energy Technology Data Exchange (ETDEWEB)

    Muljadi, E. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Zhang, Y. C. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Allen, A. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Singh, M. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Gevorgian, V. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Wan, Y. H. [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2014-02-01

    The U.S. power industry is undertaking several initiatives that will improve the operations of the electric power grid. One of those is the implementation of wide-area measurements using phasor measurement units to dynamically monitor the operations and status of the network and provide advanced situational awareness and stability assessment. The overviews of synchrophasors and stability analyses in this report are intended to present the potential future applications of synchrophasors for power system operations under high penetrations of wind and other renewable energy sources.

  14. Wind Generator & Biomass No-draft Gasification Hybrid

    Science.gov (United States)

    Hein, Matthew R.

    The premise of this research is that underutilized but vast intermittent renewable energy resources, such as wind, can become more market competitive by coupling with storable renewable energy sources, like biomass; thereby creating a firm capacity resource. Specifically, the Midwest state of South Dakota has immense wind energy potential that is not used because of economic and logistic barriers of electrical transmission or storage. Coupling the state's intermittent wind resource with another of the state's energy resources, cellulosic non-food biomass, by using a wind generator and no-draft biomass gasification hybrid system will result in a energy source that is both firm and storable. The average energy content of common biomass feedstock was determined, 14.8 MJ/kg (7.153 Btu/lb), along with the assumed typical biomass conversion efficiency of the no-draft gasifier, 65%, so that an average electrical energy round trip efficiency (RTE) of 214% can be expected (i.e. One unit of wind electrical energy can produce 2.14 kWh of electrical energy stored as syngas.) from a wind generator and no-draft biomass gasification system. Wind characteristics are site specific so this analysis utilizes a synthetic wind resource to represent a statistically sound gross representation of South Dakota's wind regime based on data from the Wind Resource Assessment Network (WRAN) locations. A synthetic wind turbine generated from common wind turbine power curves and scaled to 1-MW rated capacity was utilized for this analysis in order to remove equipment bias from the results. A standard 8,760-hour BIN Analysis model was constructed within HOMER, powerful simulation software developed by the National Renewable Energy Laboratory (NREL) to model the performance of renewable power systems. It was found that the optimum configuration on a per-megawatt-transmitted basis required a wind generator (wind farm) rated capacity of 3-MW with an anticipated annual biomass feedstock of 26,132 GJ

  15. Wind generator with electronic variable-speed drives

    Energy Technology Data Exchange (ETDEWEB)

    David, A.; Buchheit, N.; Jakobsen, H.

    1996-12-31

    Variable speed drives have been inserted between the network and the generator on certain recent wind power facilities. They have the following advantages: the drive allows the wind generator to operate at low speed with a significant reduction in acoustic noise, an important point if the facilities are sited near populated areas; the drive optimizes energy transfer, providing a gain of 4 to 10 %; the drive can possibly replace certain mechanical parts (the starting system and it in some cases, the reduction gear); the drive not only provides better transient management in relation to the network for less mechanical stress on the wind generator, it is also able to control reactive power. One commercial drive design sold by several manufacturers has already been installed on several wind generators with outputs of between 150 and 600 kw. In addition, such a solution is extremely well suited to mixed renewable energy systems. This design uses two inverse rectifier type converters and can therefore exchange energy in both directions. The equivalent drive with a single IGBT converter on the motor side and a diode converter on the network side is the solution most widely adopted throughout industry (with more than 50, 000 units installed in France per year). It still remains to be seen whether such a solution could be profitable in wind generator application (since the cost of the drive is quite high). This technical analysis is more destined for the converter-machine assembly specialists and is presented in this document, paying particular attention as it does to the modelling of the `wind energy - generator - drive - network` assembly, the associated drive command and control strategies and the simulations obtained during various transients. A 7.5 kW test bed has been installed in the Laboratoire d`Electronique de Puissance de Clamart, enabling tests to be carried out which emulate the operation of a wind generator.

  16. Offshore winds from a new generation of European satellites

    DEFF Research Database (Denmark)

    Badger, Merete; Karagali, Ioanna; Ahsbahs, Tobias Torben

    at sea. All are important for the planning, operation, and maintenance of offshore wind farms. Typical shortcomings of SAR-based wind fields include a low sampling frequency and a need for advanced data processing in order to retrieve the wind speed at 10 m above sea level. A new generation of European...... satellites and services could lower these barriers for applications in wind energy significantly. The Sentinel-1 A/B missions by the European Space Agency (ESA) deliver C-band SAR observations at an unprecedented coverage and spatial resolution. Over the seas of Europe, approximately 200 new acquisitions...... of Europe over time. The accuracy of this new product is currently under investigation. TerraSAR-X is an X-band SAR mission by the German Aerospace Center (DLR). It offers very high-resolution imagery, which may be used for detailed studies of e.g. wind farm wakes. TerraSAR-X imagery is acquired on...

  17. Low cost infrastructure solutions for small embedded wind generators

    Energy Technology Data Exchange (ETDEWEB)

    Robb, C.

    2003-07-01

    This report gives details of a project to demonstrate novel economic solutions to increase the potential for installing small-scale embedded wind generator systems at many UK sites which have so far been dismissed as too difficult. Details are given of the first phase of the study which examined current solutions to infrastructure problems and potential techniques. The use of drilled rock anchor foundations to minimise the need for delivery of ready-mix concrete to wind turbine sites, and the use of a winch and A-frame system for erecting a wind turbine to avoid the use of cranes are discussed. The demonstration of the installation of a 50kW wind turbine on the Isle of Luing in Scotland where there is no access for cranes or larger vehicles in the second phase of the project is described. The potential for the use of these techniques on larger wind turbines is considered.

  18. Probabilistic forecasting of wind power generation using extreme learning machine

    DEFF Research Database (Denmark)

    Wan, Can; Xu, Zhao; Pinson, Pierre

    2014-01-01

    an extreme learning machine (ELM)-based probabilistic forecasting method for wind power generation. To account for the uncertainties in the forecasting results, several bootstrapmethods have been compared for modeling the regression uncertainty, based on which the pairs bootstrap method is identified......Accurate and reliable forecast of wind power is essential to power system operation and control. However, due to the nonstationarity of wind power series, traditional point forecasting can hardly be accurate, leading to increased uncertainties and risks for system operation. This paper proposes...... with the best performance. Consequently, a new method for prediction intervals formulation based on theELMand the pairs bootstrap is developed.Wind power forecasting has been conducted in different seasons using the proposed approach with the historical wind power time series as the inputs alone. The results...

  19. Breaking phase focused wave group loads on offshore wind turbine monopiles

    DEFF Research Database (Denmark)

    Ghadirian, Amin; Bredmose, Henrik; Dixen, M.

    2016-01-01

    The current method for calculating extreme wave loads on offshore wind turbine structures is based on engineering models for non-breaking regular waves. The present article has the aim of validating previously developed models at DTU, namely the OceanWave3D potential flow wave model and a coupled...

  20. Optimization of power generation from shrouded wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Foote, Tudor; Agarwal, Ramesh [Department of Mechanical Engineering and Materials Science, Washington University in St. Louis (United States)

    2013-07-01

    In past several years, several studies have shown that the shrouded wind turbines can generate greater power compared to bare turbines. The objective of this study is to determine the potential of shrouded wind turbines for increased power generation by conducting numerical simulations. An analytical/computational study is performed by employing the well-known commercial Computational Fluid Dynamics (CFD) software FLUENT. An actuator disc model is used to model the turbine. The incompressible Navier-Stokes equations and a two equation realizable {kappa}-{epsilon} model are employed in the calculations. The power coefficient Cp and generated power are calculated for a large number of cases for horizontal axis wind turbines (HAWT) of various diameters and wind speeds for both bare and shrouded turbines. The design of the shroud is optimized by employing a single objective genetic algorithm; the objective being the maximization of the power coefficient Cp. It was found that the shroud indeed increases the Cp beyond the Betz’s limit significantly and as a result the generated power; this effect is consistent with that found in the recent literature that the shrouded wind-turbines can generate greater power than the bare turbines. The optimized shape of the shroud or diffuser further increases the generated power and Cp.

  1. Cross-wind fatigue analysis of a full scale offshore wind turbine in the case of wind–wave misalignment

    DEFF Research Database (Denmark)

    Koukoura, Christina; Brown, Cameron; Natarajan, Anand

    2016-01-01

    Wind–wave misalignment is often necessary to consider during the design of offshore wind turbines due to excitation of side–side vibration and the low aerodynamic damping in that direction. The measurements from a fully instrumented 3.6 MW pitch regulated-variable speed offshore wind turbine were...

  2. Coupling of WRF meteorological model to WAM spectral wave model through sea surface roughness at the Balearic Sea: impact on wind and wave forecasts

    Science.gov (United States)

    Tolosana-Delgado, R.; Soret, A.; Jorba, O.; Baldasano, J. M.; Sánchez-Arcilla, A.

    2012-04-01

    Meteorological models, like WRF, usually describe the earth surface characteristics by tables that are function of land-use. The roughness length (z0) is an example of such approach. However, over sea z0 is modeled by the Charnock (1955) relation, linking the surface friction velocity u*2 with the roughness length z0 of turbulent air flow, z0 = α-u2* g The Charnock coefficient α may be considered a measure of roughness. For the sea surface, WRF considers a constant roughness α = 0.0185. However, there is evidence that sea surface roughness should depend on wave energy (Donelan, 1982). Spectral wave models like WAM, model the evolution and propagation of wave energy as a function of wind, and include a richer sea surface roughness description. Coupling WRF and WAM is thus a common way to improve the sea surface roughness description of WRF. WAM is a third generation wave model, solving the equation of advection of wave energy subject to input/output terms of: wind growth, energy dissipation and resonant non-linear wave-wave interactions. Third generation models work on the spectral domain. WAM considers the Charnock coefficient α a complex yet known function of the total wind input term, which depends on the wind velocity and on the Charnock coefficient again. This is solved iteratively (Janssen et al., 1990). Coupling of meteorological and wave models through a common Charnock coefficient is operationally done in medium-range met forecasting systems (e.g., at ECMWF) though the impact of coupling for smaller domains is not yet clearly assessed (Warner et al, 2010). It is unclear to which extent the additional effort of coupling improves the local wind and wave fields, in comparison to the effects of other factors, like e.g. a better bathymetry and relief resolution, or a better circulation information which might have its influence on local-scale meteorological processes (local wind jets, local convection, daily marine wind regimes, etc.). This work, within the

  3. Variable slip wind generator modeling for real-time simulation

    Energy Technology Data Exchange (ETDEWEB)

    Gagnon, R.; Brochu, J.; Turmel, G. [Hydro-Quebec, Varennes, PQ (Canada). IREQ

    2006-07-01

    A model of a wind turbine using a variable slip wound-rotor induction machine was presented. The model was created as part of a library of generic wind generator models intended for wind integration studies. The stator winding of the wind generator was connected directly to the grid and the rotor was driven by the turbine through a drive train. The variable resistors was synthesized by an external resistor in parallel with a diode rectifier. A forced-commutated power electronic device (IGBT) was connected to the wound rotor by slip rings and brushes. Simulations were conducted in a Matlab/Simulink environment using SimPowerSystems blocks to model power systems elements and Simulink blocks to model the turbine, control system and drive train. Detailed descriptions of the turbine, the drive train and the control system were provided. The model's implementation in the simulator was also described. A case study demonstrating the real-time simulation of a wind generator connected at the distribution level of a power system was presented. Results of the case study were then compared with results obtained from the SimPowerSystems off-line simulation. Results showed good agreement between the waveforms, demonstrating the conformity of the real-time and the off-line simulations. The capability of Hypersim for real-time simulation of wind turbines with power electronic converters in a distribution network was demonstrated. It was concluded that hardware-in-the-loop (HIL) simulation of wind turbine controllers for wind integration studies in power systems is now feasible. 5 refs., 1 tab., 6 figs.

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

    Energy Technology Data Exchange (ETDEWEB)

    Wakui, Tetsuya; Hashizume, Takumi; Outa, Eisuke

    1999-07-01

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

  5. Model of analysis of maximum loads in wind generators produced by extreme winds

    International Nuclear Information System (INIS)

    Herrera – Sánchez, Omar; Schellong, Wolfgang; González – Fernández, Vladimir

    2010-01-01

    The use of the wind energy by means of the wind turbines in areas of high risk of occurrence of Hurricanes comes being an important challenge for the designers of wind farm at world for some years. The wind generator is not usually designed to support this type of phenomena, for this reason the areas of high incidence of tropical hurricanes of the planning are excluded, that which, in occasions disables the use of this renewable source of energy totally, either because the country is very small, or because it coincides the area of more potential fully with that of high risk. To counteract this situation, a model of analysis of maxims loads has been elaborated taken place the extreme winds in wind turbines of great behavior. This model has the advantage of determining, in a chosen place, for the installation of a wind farm, the micro-areas with higher risk of wind loads above the acceptable for the standard classes of wind turbines. (author)

  6. Optimization of Multibrid Permanent-Magnet Wind Generator Systems

    DEFF Research Database (Denmark)

    Chen, Zhe; Li, H.; Polinder, H.

    2009-01-01

    and multibrid wind turbine configurations are obtained, and the suitable ranges of gear ratios for different power ratings are investigated. Finally, the detailed comparisons of themost cost-effective multibridPMgenerator system and the optimized direct-drive PM generator system are also presented and discussed....... The comparative results have shown that the multibrid wind turbine concept appears more cost-effective than the direct-drive concept.......This paper investigates the cost-effective ranges of gearbox ratios and power ratings of multibrid permanent-magnet (PM) wind generator systems by using a design optimization method. First, the analytical model of a multibrid wind turbine concept consisting of a single-stage gearbox and a three...

  7. Voltage Control in Wind Power Plants with Doubly Fed Generators

    DEFF Research Database (Denmark)

    Garcia, Jorge Martinez

    In this work, the process of designing a wind power plant composed of; doubly fed induction generators, a static compensator unit, mechanically switched capacitors and on-load tap changer, for voltage control is shown. The selected control structure is based on a decentralized system, since...... supplied by the doubly fed induction generator wind turbines is overcome by installing a reactive power compensator, i.e. a static compensator unit, which is coordinated with the plant control by a specific dispatcher. This dispatcher is set according to the result of the wind power plant load flow....... To release the operation of the converters during steady-state disturbances, mechanically switched capacitors are installed in the wind power plant, which due to their characteristics, they are appropriate for permanent disturbances compensation. The mechanically switched capacitors are controlled to allow...

  8. ANALYSING SOLAR-WIND HYBRID POWER GENERATING SYSTEM

    Directory of Open Access Journals (Sweden)

    Mustafa ENGİN

    2005-02-01

    Full Text Available In this paper, a solar-wind hybrid power generating, system that will be used for security lighting was designed. Hybrid system was installed and solar cells, wind turbine, battery bank, charge regulators and inverter performance values were measured through the whole year. Using measured values of overall system efficiency, reliability, demanded energy cost per kWh were calculated, and percentage of generated energy according to resources were defined. We also include in the paper a discussion of new strategies to improve hybrid power generating system performance and demanded energy cost per kWh.

  9. Conceptual survey of generators and power electronics for wind turbines

    DEFF Research Database (Denmark)

    Hansen, L.H.; Helle, L.; Blaabjerg, F.

    2002-01-01

    This report presents a survey on generator concepts and power electronic concepts for wind turbines. The report is aimed as a tool for decision-makers and development people with respect to wind turbine manufactures, utilities, and independent systemoperators as well as manufactures of generators...... and power electronics. The survey is focused on the electric development of wind turbines and it yields an overview on: - State of the art on generators and power electronics. - future concepts andtechnologies within generators and power electronics. - market needs in the shape of requirements to the grid...... connection, and - consistent system solutions, plus an evaluation of these seen in the prospect of market needs. This survey on of generatorand power electronic concepts was carried out in co-operation between Aalborg University and Risø National Laboratory in the scope of the research programme Electric...

  10. Smoothing Control of Wind Farm Output by Using Kinetic Energy of Variable Speed Wind Power Generators

    Science.gov (United States)

    Sato, Daiki; Saitoh, Hiroumi

    This paper proposes a new control method for reducing fluctuation of power system frequency through smoothing active power output of wind farm. The proposal is based on the modulation of rotaional kinetic energy of variable speed wind power generators through power converters between permanent magnet synchronous generators (PMSG) and transmission lines. In this paper, the proposed control is called Fluctuation Absorption by Flywheel Characteristics control (FAFC). The FAFC can be easily implemented by adding wind farm output signal to Maximum Power Point Tracking control signal through a feedback control loop. In order to verify the effectiveness of the FAFC control, a simulation study was carried out. In the study, it was assumed that the wind farm consisting of PMSG type wind power generator and induction machine type wind power generaotors is connected with a power sysem. The results of the study show that the FAFC control is a useful method for reducing the impacts of wind farm output fluctuation on system frequency without additional devices such as secondary battery.

  11. Study on Micro Wind Generator System for Automobile

    Science.gov (United States)

    Fujimoto, Koji; Washizu, Shinsuke; Ichikawa, Tomohiko; Yukita, Kazuto; Goto, Yasuyuki; Ichiyanagi, Katsuhiro; Oshima, Takamitsu; Hayashi, Niichi; Tobi, Nobuo

    This paper proposes the micro wind generator system for automobile. This proposes system is composed of the deflector, the micro windmill, the generator, and electric storage device. Then, the effectiveness is confirmed from an examination using air blower. Therefore, new energy can be expected to be obtained by installing this system in the truck.

  12. Feasibility of wind power generation in Ghana | Ayensu | Journal of ...

    African Journals Online (AJOL)

    For payback period of 10 years, the projected cost of the energy produced by a single turbine was estimated to be GHC 0.30 (~ 20 cents) per kWh (compared to 14 cents/kWh for photovoltaic generation and 10 cents/kWh for solar thermal), which therefore makes large scale optimized wind power generation competitive in ...

  13. Infragravity wave generation and dynamics over a mild slope beach : Experiments and numerical computations

    Science.gov (United States)

    Cienfuegos, R.; Duarte, L.; Hernandez, E.

    2008-12-01

    Charasteristic frequencies of gravity waves generated by wind and propagating towards the coast are usually comprised between 0.05Hz and 1Hz. Nevertheless, lower frequecy waves, in the range of 0.001Hz and 0.05Hz, have been observed in the nearshore zone. Those long waves, termed as infragravity waves, are generated by complex nonlinear mechanisms affecting the propagation of irregular waves up to the coast. The groupiness of an incident random wave field may be responsible for producing a slow modulation of the mean water surface thus generating bound long waves travelling at the group speed. Similarly, a quasi- periodic oscillation of the break-point location, will be accompained by a slow modulation of set-up/set-down in the surf zone and generation and release of long waves. If the primary structure of the carrying incident gravity waves is destroyed (e.g. by breaking), forced long waves can be freely released and even reflected at the coast. Infragravity waves can affect port operation through resonating conditions, or strongly affect sediment transport and beach morphodynamics. In the present study we investigate infragravity wave generation mechanisms both, from experiments and numerical computations. Measurements were conducted at the 70-meter long wave tank, located at the Instituto Nacional de Hidraulica (Chile), prepared with a beach of very mild slope of 1/80 in order to produce large surf zone extensions. A random JONSWAP type wave field (h0=0.52m, fp=0.25Hz, Hmo=0.17m) was generated by a piston wave-maker and measurements of the free surface displacements were performed all over its length at high spatial resolution (0.2m to 1m). Velocity profiles were also measured at four verticals inside the surf zone using an ADV. Correlation maps of wave group envelopes and infragravity waves are computed in order to identify long wave generation and dynamics in the experimental set-up. It appears that both mechanisms (groupiness and break-point oscillation) are

  14. Reactive power management of power networks with wind generation

    CERN Document Server

    Amaris, Hortensia; Ortega, Carlos Alvarez

    2012-01-01

    As the energy sector shifts and changes to focus on renewable technologies, the optimization of wind power becomes a key practical issue. Reactive Power Management of Power Networks with Wind Generation brings into focus the development and application of advanced optimization techniques to the study, characterization, and assessment of voltage stability in power systems. Recent advances on reactive power management are reviewed with particular emphasis on the analysis and control of wind energy conversion systems and FACTS devices. Following an introduction, distinct chapters cover the 5 key

  15. Alliance created to study wind-generated power potential

    International Nuclear Information System (INIS)

    Anon.

    1991-01-01

    Wind-generated power may get a boost from a new consortium of companies that have joined together to expand the potential across the country for this cheap, renewable energy source. Niagara Mohawk Power Corporation has announced that it will join with the Pacific Gas and Electric Company (PG ampersand E), the Electric Power Research Institute (EPRI) and US Windpower, Inc., in developing an advanced, 33-meter, variable-speed wind turbine that reduced the cost and improves the power quality of wind energy. The majority of the estimated $20 million cost will be provided by US Windpower

  16. Hybrid Test Bed of Wind Electric Generator with Photovoltaic Panels

    OpenAIRE

    G.D.Anbarasi Jebaselvi; S.Paramasivam

    2014-01-01

    Driven by the increasing costs of power production and decreasing fossil fuel reserves with the addition of global environmental concerns, renewable energy is now becoming significant fraction of total electricity production in the world. Advancements in the field of wind electric generator technology and power electronics help to achieve rapid progress in hybrid power system which mainly involves wind, solar and diesel energy with a good battery back-up. Here the discussion brings about the ...

  17. Electric Generators and their Control for Large Wind Turbines

    DEFF Research Database (Denmark)

    Boldea, Ion; Tutelea, Lucian; Rallabandi, Vandana

    2017-01-01

    induction generator, the cage rotor induction generator, and the synchronous generator with DC or permanent magnet excitation. The operating principle, performance, optimal design, and the modeling and control of the machine-side converter for each kind of generator are adressed and evaluated. In view......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...... of the fact that individual power rating of WTs has increased to around 10 MW, generator design and control technologies required to reach this power rating are discussed....

  18. Windmills: Ancestors of the wind power generation

    Institute of Scientific and Technical Information of China (English)

    Cesare ROSSI; Flavio RUSSO; Sergio SAVINO

    2017-01-01

    A brief description of the windmills from the second millennium BC to the Renaissance is presented.This survey is a part of several studies conducted by the authors on technology in the ancient world.The windmills are the first motor,other than human muscles,and are the ancestors of the modem wind turbines.Some authors' virtual reconstructions of old windmills are also presented.The paper shows that the operating principle of many modem machines had already been conceived in the ancient times by using a technology that was more advanced than expected,but with two main differences,as follows:Similar tasks were accomplished by using much less energy;and the environmental impact was nil or very low.Modem designers should sometimes consider simplicity rather than the use of a large amount of energy.

  19. Windmills: Ancestors of the wind power generation

    Science.gov (United States)

    Rossi, Cesare; Russo, Flavio; Savino, Sergio

    2017-09-01

    A brief description of the windmills from the second millennium BC to the Renaissance is presented. This survey is a part of several studies conducted by the authors on technology in the ancient world. The windmills are the first motor, other than human muscles, and are the ancestors of the modern wind turbines. Some authors' virtual reconstructions of old windmills are also presented. The paper shows that the operating principle of many modern machines had already been conceived in the ancient times by using a technology that was more advanced than expected, but with two main differences, as follows: Similar tasks were accomplished by using much less energy; and the environmental impact was nil or very low. Modern designers should sometimes consider simplicity rather than the use of a large amount of energy.

  20. Wave loads on foundations for wind turbines. A literature survey; Vaaglaster paa fundament till vindkraftverk - systemdynamik och utmattning: Litteraturstudie

    Energy Technology Data Exchange (ETDEWEB)

    Carlen, Ingemar

    2001-05-01

    This report is an overview of literature covering the influence of wave loads on foundations for wind power plants. Relevant subjects are wave motion, wave forces on slender structures, wave statistics for the Swedish coast together with planning and certification.

  1. Extreme winds and waves for offshore turbines: Coupling atmosphere and wave modeling for design and operation in coastal zones

    DEFF Research Database (Denmark)

    Larsén, Xiaoli Guo; Bolanos, Rodolfo; Du, Jianting

    modeling for oshore wind farms. This modeling system consists of the atmospheric Weather Research and Forecasting (WRF) model, the wave model SWAN and an interface the Wave Boundary Layer Model WBLM, within the framework of coupled-ocean-atmosphere-wave-sediment transport modeling system COAWST...... (Hereinafter the WRF-WBLM-SWAN model). WBLM is implemented in SWAN, and it calculates stress and kinetic energy budgets in the lowest atmospheric layer where the wave-induced stress is introduced to the atmospheric modeling. WBLM ensures consistent calculation of stress for both the atmospheric and wave......, which can aect the choice of the off-shore wind turbine type. X-WiWa examined various methodologies for wave modeling. The offline coupling system using atmospheric data such as WRF or global reanalysis wind field to the MIKE 21 SW model has been improved with considerations of stability, air density...

  2. 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.

  3. Waves in the Red Sea: Response to monsoonal and mountain gap winds

    KAUST Repository

    Ralston, David K.; Jiang, Houshuo; Farrar, J. Thomas

    2013-01-01

    An unstructured grid, phase-averaged wave model forced with winds from a high resolution atmospheric model is used to evaluate wind wave conditions in the Red Sea over an approximately 2-year period. The Red Sea lies in a narrow rift valley

  4. The effects of tropical wind data on the prediction of ultralong waves

    Science.gov (United States)

    Baker, W. E.

    1981-01-01

    The influence of tropical wind data on the prediction of planetary waves were studied. Two assimilation experiments were performed, one with and one without FGGE tropical winds. The planetary wave error was then analyzed in 72 h forecasts from the initial conditions provided by the two assimilations.

  5. Aero-Hydro-Elastic Simulation Platform for Wave Energy Systems and floating Wind Turbines

    DEFF Research Database (Denmark)

    Kallesøe, Bjarne Skovmose

    This report present results from the PSO project 2008-1-10092 entitled Aero-Hydro-Elastic Simulation Platform for Wave Energy Systems and floating Wind Turbines that deals with measurements, modelling and simulations of the world’s first combined wave and wind energy platform. The floating energy...

  6. Wave modelling for the North Indian Ocean using MSMR analysed winds

    Digital Repository Service at National Institute of Oceanography (India)

    Vethamony, P.; Sudheesh, K.; Rupali, S.P.; Babu, M.T.; Jayakumar, S.; Saran, A; Basu, S.K.; Kumar, R.; Sarkar, A

    prediction when NCMRWF winds blended with MSMR winds are utilised in the wave model. A comparison between buoy and TOPEX wave heights of May 2000 at 4 buoy locations provides a good match, showing the merit of using altimeter data, wherever it is difficult...

  7. 76 FR 74776 - Forum-Trends in Extreme Winds, Waves, and Extratropical Storms Along the Coasts

    Science.gov (United States)

    2011-12-01

    ... Winds, Waves, and Extratropical Storms Along the Coasts AGENCY: National Environmental Satellite, Data...-extratropical-storms/home . FOR FURTHER INFORMATION CONTACT: Brooke Stewart, National Climatic Data Center, 151.../noaa.gov/extreme-winds-waves-extratropical-storms/home . Topics To Be Addressed This forum will address...

  8. Fatigue and extreme wave loads on bottom fixed offshore wind turbines. Effects from fully nonlinear wave forcing on the structural dynamics

    DEFF Research Database (Denmark)

    Schløer, Signe

    2013-01-01

    wind farms. As wind farms are being moved further offshore the wave loads become larger compared to the wind loads and therefore more important in the design of offshore wind turbines. Yet, the water depth is still only shallow or intermediate where the waves should be described by nonlinear irregular...

  9. The energy balance of wind waves and the remote sensing problem

    Science.gov (United States)

    Hasselmann, K.

    1972-01-01

    Measurements of wave growth indicate an energy balance of the wave spectrum governed primarily by input from the atmosphere, nonlinear transfer to shorter and longer waves, and advection. The pronounced spectral peak and sharp low frequency cut-off characteristic of fetch-limited spectra are explained as a self-stabilizing feature of the nonlinear wave-wave interactions. The momentum transferred from the atmosphere to the wind waves accounts for a large part of the wind drag. These findings are relevant for remote microwave sensing of the sea surface by backscatter and passive radiometry methods.

  10. Enhancing Wave Energy Competitiveness through Co-Located Wind and Wave Energy Farms. A Review on the Shadow Effect

    Directory of Open Access Journals (Sweden)

    Sharay Astariz

    2015-07-01

    Full Text Available Wave energy is one of the most promising alternatives to fossil fuels due to the enormous available resource; however, its development may be slowed as it is often regarded as uneconomical. The largest cost reductions are expected to be obtained through economies of scale and technological progress. In this sense, the incorporation of wave energy systems into offshore wind energy farms is an opportunity to foster the development of wave energy. The synergies between both renewables can be realised through these co-located energy farms and, thus, some challenges of offshore wind energy can be met. Among them, this paper focuses on the longer non-operational periods of offshore wind turbines—relative to their onshore counterparts—typically caused by delays in maintenance due to the harsh marine conditions. Co-located wave energy converters would act as a barrier extracting energy from the waves and resulting in a shielding effect over the wind farm. On this basis, the aim of this paper is to analyse wave energy economics in a holistic way, as well as the synergies between wave and offshore wind energy, focusing on the shadow effect and the associated increase in the accessibility to the wind turbines.

  11. Introduction Of Wavestar Wave Energy Converters At The Danish Offshore Wind Power Plant Horns Rev 2

    DEFF Research Database (Denmark)

    Marquis, L.; Kramer, Morten; Kringelum, J.

    is to be connected to a wind turbine at the DONG Energy owned wind power plant Horns Rev 2 placed off the western coast of Denmark. The plant delivers its energy production to a transformer station owned by Energinet.dk. Energinet.dk has the obligation to ensure that power is transmitted to the Danish consumers...... with this combination. This can increase the value of the produced power from future wind/wave plants. Further potential synergies of combining wind and wave energy in the same area include increased energy production from the available area and sharing of infrastructure costs as well as O&M facilities. In a future....... If Executed the project will be the first one in the world where wind and wave power are combined at full scale. The goal of the project is to evaluate the opportunities of combining wind and wave energy production on a commercial scale and to demonstrate the reduction of energy fluctuations...

  12. Fully Coupled Three-Dimensional Dynamic Response of a TLP Floating Wind Turbine in Waves and Wind

    DEFF Research Database (Denmark)

    Ramachandran, Gireesh Kumar V.R.; Bredmose, Henrik; Sørensen, Jens Nørkær

    2013-01-01

    is a consequence of the wave-induced rotor dynamics. In the absence of a controller scheme for the wind turbine, the rotor torque fluctuates considerably, which induces a growing roll response especially when the wind turbine is operated nearly at the rated wind speed. This can be eliminated either...... by appropriately adjusting the controller so as to regulate the torque or by optimizing the floater or tendon dimensions, thereby limiting the roll motion. Loads and coupled responses are predicted for a set of load cases with different wave headings. Based on the results, critical load cases are identified...

  13. Impact of an offshore wind farm on wave conditions and shoreline development

    DEFF Research Database (Denmark)

    Christensen, Erik Damgaard; Kristensen, Sten Esbjørn; Deigaard, Rolf

    2014-01-01

    the shoreline’s sensitivity to the distance from the OWF to the shoreline was studied. The effect of the reduced wind speed inside and on the lee side of the offshore wind farm was incorporated in a parameterized way in a spectral wind wave model. The shoreline impact was studied with a one-line model....

  14. Comparison of superconducting generators and permanent magnet generators for 10-MW direct-drive wind turbines

    DEFF Research Database (Denmark)

    Liu, Dong; Polinder, Henk; Abrahamsen, Asger Bech

    2016-01-01

    Large offshore direct-drive wind turbines of 10-MW power levels are being extensively proposed and studied because of a reduced cost of energy. Conventional permanent magnet generators currently dominating the direct-drive wind turbine market are still under consideration for such large wind...... turbines. In the meantime, superconducting generators (SCSGs) have been of particular interest to become a significant competitor because of their compactness and light weight. This paper compares the performance indicators of these two direct-drive generator types in the same 10-MW wind turbine under...... the same design and optimization method. Such comparisons will be interesting and insightful for commercialization of superconducting generators and for development of future wind energy industry, although SCSGs are still far from a high technology readiness level. The results show that the SCSGs may...

  15. Wind turbine integrated multipole permanent magnet generator (PMG)

    Energy Technology Data Exchange (ETDEWEB)

    Vilsboell, N.; Pinegin, A.; Goussarov, D.

    1996-01-01

    Designed permanent magnet generator (PMG - 20 kW) possesses a number of advantages: it makes possible to replace gearbox, the generator and possibly the hub of the wind turbine by combining wind rotor with external rotor of the generator; use of rare earth magnets Nd-Fe-B allows to reduce mass and dimensions of the generator; use of the PMG for wind turbines increases the reliability of the construction during the life time, comparing to the conventional design (gearbox, asynchronous generator). The test of the PMG -20 kW informs that design method, developed for calculation of multipole permanent magnet generators is correct in general and meets engineering requirements. The calculation uncertainty of the magnetic system and output characteristics does not exceed 2-3%. The test shows, that the maximum efficiency of the PGM - 20 kW with full load can be achieved as high as 90-91.5% and excels the efficiency of the traditional system `generator-gearbox` by 4-5.5%. Designing permanent magnet generator, it is recommended to take into account voltage stabilization (capacitance). Efficiency is expected to be higher, mass and production cost of the generator can be reduced by 25-30%. The frequency converter shall be used not only for control of rotational speed, but also to obtain sinusoidal capacitive current on the generator side. For PMG - 20 kW the angle between voltage and current should be within the range 0-23%. (au)

  16. Swell impact on wind stress and atmospheric mixing in a regional coupled atmosphere-wave model

    DEFF Research Database (Denmark)

    Wu, Lichuan; Rutgersson, Anna; Sahlée, Erik

    2016-01-01

    Over the ocean, the atmospheric turbulence can be significantly affected by swell waves. Change in the atmospheric turbulence affects the wind stress and atmospheric mixing over swell waves. In this study, the influence of swell on atmospheric mixing and wind stress is introduced into an atmosphere-wave-coupled...... regional climate model, separately and combined. The swell influence on atmospheric mixing is introduced into the atmospheric mixing length formula by adding a swell-induced contribution to the mixing. The swell influence on the wind stress under wind-following swell, moderate-range wind, and near......-neutral and unstable stratification conditions is introduced by changing the roughness length. Five year simulation results indicate that adding the swell influence on atmospheric mixing has limited influence, only slightly increasing the near-surface wind speed; in contrast, adding the swell influence on wind stress...

  17. Dynamics and Control of Lateral Tower Vibrations in Offshore Wind Turbines by Means of Active Generator Torque

    Directory of Open Access Journals (Sweden)

    Zili Zhang

    2014-11-01

    Full Text Available Lateral tower vibrations of offshore wind turbines are normally lightly damped, and large amplitude vibrations induced by wind and wave loads in this direction may significantly shorten the fatigue life of the tower. This paper proposes the modeling and control of lateral tower vibrations in offshore wind turbines using active generator torque. To implement the active control algorithm, both the mechanical and power electronic aspects have been taken into consideration. A 13-degrees-of-freedom aeroelastic wind turbine model with generator and pitch controllers is derived using the Euler–Lagrangian approach. The model displays important features of wind turbines, such as mixed moving frame and fixed frame-defined degrees-of-freedom, couplings of the tower-blade-drivetrain vibrations, as well as aerodynamic damping present in different modes of motions. The load transfer mechanisms from the drivetrain and the generator to the nacelle are derived, and the interaction between the generator torque and the lateral tower vibration are presented in a generalized manner. A three-dimensional rotational sampled turbulence field is generated and applied to the rotor, and the tower is excited by a first order wave load in the lateral direction. Next, a simple active control algorithm is proposed based on active generator torques with feedback from the measured lateral tower vibrations. A full-scale power converter configuration with a cascaded loop control structure is also introduced to produce the feedback control torque in real time. Numerical simulations have been carried out using data calibrated to the referential 5-MW NREL (National Renewable Energy Laboratory offshore wind turbine. Cases of drivetrains with a gearbox and direct drive to the generator are considered using the same time series for the wave and turbulence loadings. Results show that by using active generator torque control, lateral tower vibrations can be significantly mitigated for

  18. High Power Wind Generator Designs with Less or No PMs

    DEFF Research Database (Denmark)

    Boldea, Ion; Tutelea, Lucian; Blaabjerg, Frede

    2014-01-01

    synchronous generators, by doubly-fed (wound rotor) induction and cage induction generators and by introducing new topologies with pertinent costs for high power (MW range) wind energy conversion units. The present overview attempts, based on recent grid specifications, an evaluation of commercial and novel...... considering the interaction with the PWM converter in terms of power/speed range, losses, kVA, and costs) rather than on the control issues which abound in literature, will be of use for future R&D efforts in wind energy conversion, storage and use.......The recent steep increase in high energy permanent magnet (PM) price (above 130$/kg and more) triggered already strong R&D efforts to develop wind generators with less PMs (less weight in NdFeB magnets/kW or the use of ferrite PMs) or fully without PMs. All these by optimizing existing dc excited...

  19. Variability in large-scale wind power generation: Variability in large-scale wind power generation

    Energy Technology Data Exchange (ETDEWEB)

    Kiviluoma, Juha [VTT Technical Research Centre of Finland, Espoo Finland; Holttinen, Hannele [VTT Technical Research Centre of Finland, Espoo Finland; Weir, David [Energy Department, Norwegian Water Resources and Energy Directorate, Oslo Norway; Scharff, Richard [KTH Royal Institute of Technology, Electric Power Systems, Stockholm Sweden; Söder, Lennart [Royal Institute of Technology, Electric Power Systems, Stockholm Sweden; Menemenlis, Nickie [Institut de recherche Hydro-Québec, Montreal Canada; Cutululis, Nicolaos A. [DTU, Wind Energy, Roskilde Denmark; Danti Lopez, Irene [Electricity Research Centre, University College Dublin, Dublin Ireland; Lannoye, Eamonn [Electric Power Research Institute, Palo Alto California USA; Estanqueiro, Ana [LNEG, Laboratorio Nacional de Energia e Geologia, UESEO, Lisbon Spain; Gomez-Lazaro, Emilio [Renewable Energy Research Institute and DIEEAC/EDII-AB, Castilla-La Mancha University, Albacete Spain; Zhang, Qin [State Grid Corporation of China, Beijing China; Bai, Jianhua [State Grid Energy Research Institute Beijing, Beijing China; Wan, Yih-Huei [National Renewable Energy Laboratory, Transmission and Grid Integration Group, Golden Colorado USA; Milligan, Michael [National Renewable Energy Laboratory, Transmission and Grid Integration Group, Golden Colorado USA

    2015-10-25

    The paper demonstrates the characteristics of wind power variability and net load variability in multiple power systems based on real data from multiple years. Demonstrated characteristics include probability distribution for different ramp durations, seasonal and diurnal variability and low net load events. The comparison shows regions with low variability (Sweden, Spain and Germany), medium variability (Portugal, Ireland, Finland and Denmark) and regions with higher variability (Quebec, Bonneville Power Administration and Electric Reliability Council of Texas in North America; Gansu, Jilin and Liaoning in China; and Norway and offshore wind power in Denmark). For regions with low variability, the maximum 1 h wind ramps are below 10% of nominal capacity, and for regions with high variability, they may be close to 30%. Wind power variability is mainly explained by the extent of geographical spread, but also higher capacity factor causes higher variability. It was also shown how wind power ramps are autocorrelated and dependent on the operating output level. When wind power was concentrated in smaller area, there were outliers with high changes in wind output, which were not present in large areas with well-dispersed wind power.

  20. Reducing storage of global wind ensembles with stochastic generators

    KAUST Repository

    Jeong, Jaehong

    2018-03-09

    Wind has the potential to make a significant contribution to future energy resources. Locating the sources of this renewable energy on a global scale is however extremely challenging, given the difficulty to store very large data sets generated by modern computer models. We propose a statistical model that aims at reproducing the data-generating mechanism of an ensemble of runs via a Stochastic Generator (SG) of global annual wind data. We introduce an evolutionary spectrum approach with spatially varying parameters based on large-scale geographical descriptors such as altitude to better account for different regimes across the Earth’s orography. We consider a multi-step conditional likelihood approach to estimate the parameters that explicitly accounts for nonstationary features while also balancing memory storage and distributed computation. We apply the proposed model to more than 18 million points of yearly global wind speed. The proposed SG requires orders of magnitude less storage for generating surrogate ensemble members from wind than does creating additional wind fields from the climate model, even if an effective lossy data compression algorithm is applied to the simulation output.

  1. Reducing storage of global wind ensembles with stochastic generators

    KAUST Repository

    Jeong, Jaehong; Castruccio, Stefano; Crippa, Paola; Genton, Marc G.

    2018-01-01

    Wind has the potential to make a significant contribution to future energy resources. Locating the sources of this renewable energy on a global scale is however extremely challenging, given the difficulty to store very large data sets generated by modern computer models. We propose a statistical model that aims at reproducing the data-generating mechanism of an ensemble of runs via a Stochastic Generator (SG) of global annual wind data. We introduce an evolutionary spectrum approach with spatially varying parameters based on large-scale geographical descriptors such as altitude to better account for different regimes across the Earth’s orography. We consider a multi-step conditional likelihood approach to estimate the parameters that explicitly accounts for nonstationary features while also balancing memory storage and distributed computation. We apply the proposed model to more than 18 million points of yearly global wind speed. The proposed SG requires orders of magnitude less storage for generating surrogate ensemble members from wind than does creating additional wind fields from the climate model, even if an effective lossy data compression algorithm is applied to the simulation output.

  2. Wind Generation Participation in Power System Frequency Response: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Gevorgian, Vahan; Zhang, Yingchen

    2017-01-01

    The electrical frequency of an interconnected power system must be maintained close its nominal level at all times. Excessive under- and overfrequency excursions can lead to load shedding, instability, machine damage, and even blackouts. There is a rising concern in the electric power industry in recent years about the declining amount of inertia and primary frequency response (PFR) in many interconnections. This decline may continue due to increasing penetrations of inverter-coupled generation and the planned retirements of conventional thermal plants. Inverter-coupled variable wind generation is capable of contributing to PFR and inertia with a response that is different from that of conventional generation. It is not yet entirely understood how such a response will affect the system at different wind power penetration levels. The modeling work presented in this paper evaluates the impact of wind generation's provision of these active power control strategies on a large, synchronous interconnection. All simulations were conducted on the U.S. Western Interconnection with different levels of instantaneous wind power penetrations (up to 80%). The ability of wind power plants to provide PFR - and a combination of synthetic inertial response and PFR - significantly improved the frequency response performance of the system.

  3. An artificial generation of a few specific wave conditions: New simulator design and experimental performance

    International Nuclear Information System (INIS)

    Ramadan, A.; Mohamed, M.H.; Marzok, S.Y.; Montasser, O.A.; El Feky, A.; El Baz, A.R.

    2014-01-01

    In recent years, an amplified global awareness has led to a reawakening of interest in renewable energy technology. In an effort to reduce the worldwide dependence on fossil fuels, cleaner power generation methods are being sought in the field of solar, biomass, wind and wave energy. The importance of wave energy is increased in particular in some countries like UK, Portugal, Spain and Japan. A considerable progress has already been achieved in this field but the available technical designs are not adequate to develop reliable wave energy converters. Wave energy is the most available energy associated in water seas and oceans. Simultaneously, the wave energy has consisted of two types of energies: potential and kinetic energy. Therefore, many attempts have been applied to capture these energies. In the present work, a wave generator device has been designed and manufactured to simulate and generate the heaving motion of sea waves with different specification. A PC based electro-pneumatic control system was designed and implemented to individually control wave height, these heights are 3, 8, 16, 18 and 20 cm and different frequencies to generate these regular and irregular waves. - Highlights: • Wave energy is one of the most promising sources of renewable energy. • Most researchers built huge flume to simulate waves with large size and high budget. • A new simulator design for the direct and indirect wave energy is introduced. • The regular and irregular wave can be obtained for the new wave simulator. • This design is compact, flexible in terms amplitude, frequencies and high accuracy

  4. The environmental interactions of tidal and wave energy generation devices

    Energy Technology Data Exchange (ETDEWEB)

    Frid, Chris, E-mail: c.l.j.frid@liv.ac.uk [School of Environmental Sciences, University of Liverpool, Crown Street, Liverpool, L69 7ZB (United Kingdom); Andonegi, Eider, E-mail: eandonegi@azti.es [AZTI-Tecnalia, Txatxarramendi ugartea, z/g E-48395 Sukarrieta (Bizkaia) (Spain); Depestele, Jochen, E-mail: jochen.depestele@ilvo.vlaanderen.be [Institute for Agricultural and Fisheries Research, Ankerstraat 1, B-8400 Oostende (Belgium); Judd, Adrian, E-mail: Adrian.Judd@cefas.co.uk [Centre for Environment, Fisheries and Aquaculture Science , Lowestoft Laboratory, Pakefield Road, Lowestoft NR33 0HT United Kingdom (United Kingdom); Rihan, Dominic, E-mail: Dominic.RIHAN@ec.europa.eu [Irish Sea Fisheries Board, P.O. Box 12 Dun Laoghaire, Co. Dublin (Ireland); Rogers, Stuart I., E-mail: stuart.rogers@cefas.co.uk [Centre for Environment, Fisheries and Aquaculture Science , Lowestoft Laboratory, Pakefield Road, Lowestoft NR33 0HT United Kingdom (United Kingdom); Kenchington, Ellen, E-mail: Ellen.Kenchington@dfo-mpo.gc.ca [Fisheries and Oceans Canada, Bedford Institute of Oceanography, P.O. Box 1006, Dartmouth Canada, NS B2Y 4A2 (Canada)

    2012-01-15

    Global energy demand continues to grow and tidal and wave energy generation devices can provide a significant source of renewable energy. Technological developments in offshore engineering and the rising cost of traditional energy means that offshore energy resources will be economic in the next few years. While there is now a growing body of data on the ecological impacts of offshore wind farms, the scientific basis on which to make informed decisions about the environmental effects of other offshore energy developments is lacking. Tidal barrages have the potential to cause significant ecological impacts particularly on bird feeding areas when they are constructed at coastal estuaries or bays. Offshore tidal stream energy and wave energy collectors offer the scope for developments at varying scales. They also have the potential to alter habitats. A diversity of designs exist, including floating, mid-water column and seabed mounted devices, with a variety of moving-part configurations resulting in a unique complex of potential environmental effects for each device type, which are discussed to the extent possible. - Highlights: Black-Right-Pointing-Pointer We review the environmental impacts of tidal barrages and fences, tidal stream farms and wave energy capture devices. Black-Right-Pointing-Pointer Impacts on habitats, species and the water column, and effects of noise and electromagnetic fields are considered. Black-Right-Pointing-Pointer Tidal barrages can cause significant impacts on bird feeding areas when constructed at coastal estuaries or bays. Black-Right-Pointing-Pointer Wave energy collectors can alter water column and sea bed habitats locally and over large distances.

  5. Twenty-first century wave climate projections for Ireland and surface winds in the North Atlantic Ocean

    Science.gov (United States)

    Gallagher, Sarah; Gleeson, Emily; Tiron, Roxana; McGrath, Ray; Dias, Frédéric

    2016-04-01

    Ireland has a highly energetic wave and wind climate, and is therefore uniquely placed in terms of its ocean renewable energy resource. The socio-economic importance of the marine resource to Ireland makes it critical to quantify how the wave and wind climate may change in the future due to global climate change. Projected changes in winds, ocean waves and the frequency and severity of extreme weather events should be carefully assessed for long-term marine and coastal planning. We derived an ensemble of future wave climate projections for Ireland using the EC-Earth global climate model and the WAVEWATCH III® wave model, by comparing the future 30-year period 2070-2099 to the period 1980-2009 for the RCP4.5 and the RCP8.5 forcing scenarios. This dataset is currently the highest resolution wave projection dataset available for Ireland. The EC-Earth ensemble predicts decreases in mean (up to 2 % for RCP4.5 and up to 3.5 % for RCP8.5) 10 m wind speeds over the North Atlantic Ocean (5-75° N, 0-80° W) by the end of the century, which will consequently affect swell generation for the Irish wave climate. The WAVEWATCH III® model predicts an overall decrease in annual and seasonal mean significant wave heights around Ireland, with the largest decreases in summer (up to 15 %) and winter (up to 10 %) for RCP8.5. Projected decreases in mean significant wave heights for spring and autumn were found to be small for both forcing scenarios (less than 5 %), with no significant decrease found for RCP4.5 off the west coast in those seasons.

  6. Influence of Wind Model Performance on Wave Forecasts of the Naval Oceanographic Office

    Science.gov (United States)

    Gay, P. S.; Edwards, K. L.

    2017-12-01

    Significant discrepancies between the Naval Oceanographic Office's significant wave height (SWH) predictions and observations have been noted in some model domains. The goal of this study is to evaluate these discrepancies and identify to what extent inaccuracies in the wind predictions may explain inaccuracies in SWH predictions. A one-year time series of data is evaluated at various locations in Southern California and eastern Florida. Correlations are generally quite good, ranging from 73% at Pendleton to 88% at both Santa Barbara, California, and Cape Canaveral, Florida. Correlations for month-long periods off Southern California drop off significantly in late spring through early autumn - less so off eastern Florida - likely due to weaker local wind seas and generally smaller SWH in addition to the influence of remotely-generated swell, which may not propagate accurately into and through the wave models. The results of this study suggest that it is likely that a change in meteorological and/or oceanographic conditions explains the change in model performance, partially as a result of a seasonal reduction in wind model performance in the summer months.

  7. Quantifying the Role of Atmospheric Forcing in Ice Edge Retreat and Advance Including Wind-Wave Coupling

    Science.gov (United States)

    2015-09-30

    Low-Level Profiles, Pressure, Temperature, Humidity Rawinsonde (Kite, Tethered Balloon , Unmanned Aerial vehicle) Wave Characteristics, Wind wave and...Thermistor, Ship intake, Manual Bucket Tropospheric Profiles, 4/day – Pressure, Temperature, Humidity, Wind Vector Rawinsonde (Weather Balloon

  8. Wind turbine power generation in the South Pennines

    International Nuclear Information System (INIS)

    Anon.

    1991-10-01

    This document has been produced in response to emerging demands for locating wind farms in the South Pennines region in the United Kingdom region, the absence - as yet - of any national policy guidelines and a concern that a lack of protected landscape area status may lead to increased targeting of the area for wind farm developments. Increasingly, the rich heritage based landscape of the South Pennines is gaining recognition. It is important that the basic landscape resource is conserved and enhanced. Thus the need to clarify a set of relevant guidelines against which individual proposals may be considered. It is recommended that policies for dealing with demands for wind turbine developments are based upon an appreciation of the intrinsic character of the South Pennine landscape. Similarly, it is important that the consideration of guidelines is supported by information on how demands for wind generated power have evolved and why development pressures for wind farms are now emerging in the sub-region. The document is structured as follows: (1) Wind Power -Background; (2) Wind Power in the South Pennines - The Potential; (3) The South Pennines: Landscape Character; (4) Planning Policy Guidelines. (author)

  9. Wind energy research activities of the Dutch Electricity Generating Board

    International Nuclear Information System (INIS)

    Halberg, N.

    1990-01-01

    The varying degrees of penetration of wind energy conversion systems (WECs) into the Dutch electricity generating system has been examined. A simulation has been carried out using wind data recorded at 6 sites spread across the area of interest in the Netherlands. The recorded wind data has been used in conjunction with a production costing model normally used by Sep (the Dutch Electricity Generating Board) for planning purposes. This model was modified to give a correct assessment of the quantity and value of fuel savings made by WECs. System studies were carried out for the year 2000 for zero wind penetration and for three distinctive penetration degrees of WECs, namely 5%, 10% and 15%. After incorporation of the WECS capacity, adjustments were made to the basic plant mix to allow the capacity credit WECs. Separate production cost simulations were executed for each distinct WECS capacity factor. Economic assessments were carried out using standard procedures. Except for the unpredictable development of fuel prices, the capital costs of the WECs proved to be the determinant for the economic viability of wind power. Significant improvements in costs and performance, as may be achieved through additional technological advances, are needed to made wind power competitive in widespread utility applications. (Author)

  10. Grid-connected inverter for wind power generation system

    Institute of Scientific and Technical Information of China (English)

    YANG Yong; RUAN Yi; SHEN Huan-qing; TANG Yan-yan; YANG Ying

    2009-01-01

    In wind power generation system the grid-connected inverter is an important section for energy conversion and transmission, of which the performance has a direct influence on the entire wind power generation system. The mathematical model of the grid-connected inverter is deduced firstly. Then, the space vector pulse width modulation (SVPWM) is analyzed. The power factor can be controlled close to unity, leading or lagging, which is realized based on PI-type current controller and grid voltage vector-oriented control. The control strategy is verified by the simulation and experimental results with a good sinusoidal current, a small harmonic component and a fast dynamic response.

  11. Towards the best approach for wind wave modelling in the Red Sea

    KAUST Repository

    Langodan, Sabique

    2015-04-01

    While wind and wave modelling is nowadays quite satisfactory in the open oceans, problems are still present in the enclosed seas. In general, the smaller the basin, the poorer the models perform, especially if the basin is surrounded by a complex orography. The Red Sea is an extreme example in this respect, especially because of its long and narrow shape. This deceivingly simple domain offers very interesting challenges for wind and wave modeling, not easily, if ever, found elsewhere. Depending on the season, opposite wind regimes, one directed to southeast, the other one to northwest, are present and may coexist in the most northerly and southerly parts of the Red Sea. Where the two regimes meet, the wave spectra can be rather complicated and, crucially dependent on small details of the driving wind fields. We explored how well we could reproduce the general and unusual wind and wave patterns of the Red Sea using different meteorological products. Best results were obtained using two rather opposite approaches: the high-resolution Weather Research Forecasting (WRF) regional model and the slightly enhanced surface winds from the global European Centre for Medium-Range Weather Forecasts (ECMWF) model. We discuss the reasons why these two approaches produce the best results and the implications on wave modeling in the Red Sea. The unusual wind and wave patterns in the Red Sea suggest that the currently available wave model source functions may not properly represent the evolution of local fields. However, within limits, the WAVEWATCH III wave model, based on Janssen\\'s and also Ardhuin\\'s wave model physics, provides in many cases very reasonable results. Because surface winds lead to important uncertainties in wave simulation, we also discuss the impact of data assimilation for simulating the most accurate winds, and consequently waves, over the Red Sea.

  12. Estimating generation costs for wind power production in France

    International Nuclear Information System (INIS)

    Benazet, J.F.; Probert, E.J.

    1997-01-01

    Wind power is being exploited in several European countries as one of a possible number of sources of renewable energy. However, in France there is a heavy reliance on nuclear and hydro-electric power and the potential of wind power as part of the energy mix has been virtually ignored. One of the reasons advanced for the under utilisation of this technology is that it is financially unattractive. In this paper the contribution which wind power could potentially make to overall power production levels in France is examined. A cost estimate model is developed which derives electricity generation costs and determines realistic levels of production for the future. The model automatically determines the associated number of wind turbines required and the geographical areas in which they should be located. (author)

  13. Testing of a direct drive generator for wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Sondergaard, L.M. [Riso National Laboratory, Roskilde (Denmark)

    1996-12-31

    The normal drive train of a wind turbine consists a gearbox and a 4 to 8 poles asynchronous generator. The gearbox is an expensive and unreliable components and this paper deals with testing of a direct drive synchronous generator for a gearless wind turbine. The Danish company Belt Electric has constructed and manufactured a 27 kW prototype radial flux PM-generator (DD600). They have used cheap hard ferrite magnets in the rotor of this PM-generator. This generator has been tested at Riso and the test results are investigated and analyzed in this paper. The tests have been done with three different load types (1: resistance; 2: diode rectifier, DC-capacitor, resistance; 3: AC-capacitor, diode rectifier, DC-capacitor, resistance). 1 ref., 9 figs., 5 tabs.

  14. Fuzzy logic based variable speed wind generation system

    Energy Technology Data Exchange (ETDEWEB)

    Simoes, M.G. [Sao Paulo Univ., SP (Brazil). Escola Politecnica. PMC - Mecatronica; Bose, B.K. [Tennessee Univ., Knoxville, TN (United States). Dept. of Electrical Engineering; Spiegel, Ronal J. [Environmental Protection Agency, Research Triangle Park, NC (United States). Air and Energy Engineering Research Lab.

    1996-12-31

    This work demonstrates the successful application of fuzzy logic to enhance the performance and control of a variable speed wind generation system. A maximum power point tracker control is performed with three fuzzy controllers, without wind velocity measurement, and robust to wind vortex and turbine torque ripple. A squirrel cage induction generator feeds the power to a double-sided PWM converter system which pumps the power to a utility grid or supplies to an autonomous system. The fuzzy logic controller FLC-1 searches on-line the generator speed so that the aerodynamic efficiency of the wind turbine is optimized. A second fuzzy controller FLC-2 programs the machine flux by on-line search so as to optimize the machine-converter system wind vortex. Detailed analysis and simulation studies were performed for development of the control strategy and fuzzy algorithms, and a DSP TMS320C30 based hardware with C control software was built for the performance evaluation of a laboratory experimental set-up. The theoretical development was fully validated and the system is ready to be reproduced in a higher power installation. (author) 7 refs., 3 figs., 1 tab.

  15. Maximum wind power plant generation by reducing the wake effect

    International Nuclear Information System (INIS)

    De-Prada-Gil, Mikel; Alías, César Guillén; Gomis-Bellmunt, Oriol; Sumper, Andreas

    2015-01-01

    Highlights: • To analyze the benefit of applying a new control strategy to maximise energy yield. • To operate some wind turbines at non-optimum points for reducing wake effects. • Single, partial and multiple wakes for any wind direction are taken into account. • Thrust coefficient is computed according to Blade Element Momentum (BEM) theory. - Abstract: This paper analyses, from a steady state point of view, the potential benefit of a Wind Power Plant (WPP) control strategy whose main objective is to maximise its total energy yield over its lifetime by taking into consideration that the wake effect within the WPP varies depending on the operation of each wind turbine. Unlike the conventional approach in which each wind turbine operation is optimised individually to maximise its own energy capture, the proposed control strategy aims to optimise the whole system by operating some wind turbines at sub-optimum points, so that the wake effect within the WPP is reduced and therefore the total power generation is maximised. The methodology used to assess the performance of both control approaches is presented and applied to two particular study cases. It contains a comprehensive wake model considering single, partial and multiple wake effects among turbines. The study also takes into account the Blade Element Momentum (BEM) theory to accurately compute both power and thrust coefficient of each wind turbine. The results suggest a good potential of the proposed concept, since an increase in the annual energy captured by the WPP from 1.86% up to 6.24% may be achieved (depending on the wind rose at the WPP location) by operating some specific wind turbines slightly away from their optimum point and reducing thus the wake effect

  16. Integration of a wind farm with a wave- and an aquaculture farm

    OpenAIRE

    He, J.; Weissenberger, J.; Bergh, Øivind; Hjøllo, Solfrid Sætre; Wehde, Henning; Agnalt, Ann-Lisbeth; Chen, Z.; Olason, D.; Thorsteinson, B.; Fosso, O.B.

    2011-01-01

    There is a growing interest in placing wind farms offshore. 140 GW of offshore wind are currently being planned to reach the EU energy 2020 goal. However, an offshore wind farm occupies a large area and competes with other users of the maritime space. The integration of an offshore wind farm with other marine energy producers such as wave energy and other maritime users such as aquaculture farms may result in significant benefits in terms of economics, optimising spatial utilization, and mini...

  17. Theoretical parameters of powerful radio galaxies. II. Generation of MHD turbulence by collisionless shock waves

    International Nuclear Information System (INIS)

    Baryshev, Yu.V.; Morozov, V.N.

    1988-01-01

    It is shown that MHD turbulence can be generated by collisionless shock waves due to anisotropy of the pressure behind the front of the reverse sock at the hot spot of a powerful radio galaxy. The energy density of the MHD turbulence generated behind the shock front is estimated. Analysis of the theoretical studies and experimental data on collisionless shock waves in the solar wind indicates that an important part is played by streams of ions reflected by the shock fronts, the streams generating plasma and MHD turbulence in the region ahead of the front. The extension of these ideas to shock waves in powerful radio galaxies must be made with care because of the great difference between the parameters of the shock waves in the two cases

  18. Implementation of viscoelastic mud-induced energy attenuation in the third-generation wave model, SWAN

    Science.gov (United States)

    Beyramzade, Mostafa; Siadatmousavi, Seyed Mostafa

    2018-01-01

    The interaction of waves with fluid mud can dissipate the wave energy significantly over few wavelengths. In this study, the third-generation wave model, SWAN, was advanced to include attenuation of wave energy due to interaction with a viscoelastic fluid mud layer. The performances of implemented viscoelastic models were verified against an analytical solution and viscous formulations for simple one-dimensional propagation cases. Stationary and non-stationary test cases in the Surinam coast and the Atchafalaya Shelf showed that the inclusion of the mud-wave interaction term in the third-generation wave model enhances the model performance in real applications. A high value of mud viscosity (of the order of 0.1 m2/s) was required in both field cases to remedy model overestimation at high frequency ranges of the wave spectrum. The use of frequency-dependent mud viscosity value improved the performance of model, especially in the frequency range of 0.2-0.35 Hz in the wave spectrum. In addition, the mud-wave interaction might affect the high frequency part of the spectrum, and this part of the wave spectrum is also affected by energy transfer from wind to waves, even for the fetch lengths of the order of 10 km. It is shown that exclusion of the wind input term in such cases might result in different values for parameters of mud layer when inverse modeling procedure was employed. Unlike viscous models for wave-mud interaction, the inverse modeling results to a set of mud parameters with the same performance when the viscoelastic model is used. It provides an opportunity to select realistic mud parameters which are in more agreement with in situ measurements.

  19. Wind turbine generators having wind assisted cooling systems and cooling methods

    Science.gov (United States)

    Bagepalli, Bharat [Niskayuna, NY; Barnes, Gary R [Delanson, NY; Gadre, Aniruddha D [Rexford, NY; Jansen, Patrick L [Scotia, NY; Bouchard, Jr., Charles G.; Jarczynski, Emil D [Scotia, NY; Garg, Jivtesh [Cambridge, MA

    2008-09-23

    A wind generator includes: a nacelle; a hub carried by the nacelle and including at least a pair of wind turbine blades; and an electricity producing generator including a stator and a rotor carried by the nacelle. The rotor is connected to the hub and rotatable in response to wind acting on the blades to rotate the rotor relative to the stator to generate electricity. A cooling system is carried by the nacelle and includes at least one ambient air inlet port opening through a surface of the nacelle downstream of the hub and blades, and a duct for flowing air from the inlet port in a generally upstream direction toward the hub and in cooling relation to the stator.

  20. Quasi-optical millimeter wave rotating TE62 mode generator

    International Nuclear Information System (INIS)

    Li Shaopu; Zhang Conghui; Wang Zhong; Guo Feng; Chen Hongbin; Hu Linlin; Pan Wenwu

    2011-01-01

    The design,measurement technique and experimental results of rotating TE 6 2 mode generator are presented. The source includes millimeter wave optical system and open coaxial wave guide system. The millimeter wave optical system consists of pyramid antenna, hyperbolical reflector, parabolic reflector and quasi parabolic reflector. The open coaxial wave guide system contains open coaxial wave guide cavity, cylinder wave guide and output antenna. It is tested by network analyser and millimeter wave near field pattern auto-test system, and the purity of rotating TE 6 2 mode at 96.4 GHz is about 97%. (authors)

  1. Issues and regulatory requirements for the connection of wind generation

    Energy Technology Data Exchange (ETDEWEB)

    Gimenez Alvarez, J.M. [National University of San Juan (Argentina)], E-mail: jgimenez@unsj.edu.ar; Gomez Targarona, J.C. [National University of Rio Cuarto, Cordoba (Argentina). Electric Power Systems Protection Institute (IPSEP)], E-mail: jcgomez@ing.unrc.edu.ar

    2009-07-01

    Pollution problems such as greenhouse effect as well as the high value and volatility of fuel prices have forced and accelerated the development and use of renewable energy sources. In this work a complete revision of wind generation is presented. In the first part a brief history of the wind energy developments is detailed. Next, some commentaries related to the present and future state are made. Then, a revision of the modern structures of wind generation is realized. In fourth place it is included a brief comparison between small and big size turbines. Then, different types of energy storage are mentioned. Finally regulatory aspects are discussed, respect to the treatment of the technical problems. (author)

  2. Wind Generators Test Bench. Optimal Design of PI Controller

    Directory of Open Access Journals (Sweden)

    TUDORACHE, T.

    2011-08-01

    Full Text Available This paper proposes a novel and robust strategy for the optimal design of the drive system integrated in a wind generators test bench. The PI regulator coefficients used in control systems are usually computed based on simplified hypotheses and then tuned manually so as the system response meet certain specifications in terms of stability, accuracy and speed. The proposed methodology permits the automatic identification of PI regulator coefficients using intelligent optimization algorithms, the initial guess for the search procedure being determined based on particular simplified hypotheses. The proposed procedure can help the design engineers to drastically reduce the effort for finding the best PI regulator coefficients offering a range of feasible solutions depending on the imposed optimum criteria. The characteristics and performances of the optimization strategy are highlighted by using it for the design of a DC motor drive system used to simulate the wind prime mover integrated in a wind generators test bench.

  3. Output power control of two coupled wind generators

    Directory of Open Access Journals (Sweden)

    A Boukhelifa

    2016-09-01

    Full Text Available In this paper we are interested to the power control of two wind generators coupled to the network through power converters. Every energy chain conversion is composed of a wind turbine, a gearbox, a Double Fed Induction Generator (DFIG, two PWM converters and a DC bus. The power exchange and the DC voltage are controlled by the use of proportional integral correctors. For our study, initially we have modeled all the components of the one system energy conversion, and then we have simulated its behavior using Matlab/Simulink. In another part of this paper we present the analysis of the interaction and the powerflow between the two aerogenerators following a disturbance due to wind speed on every turbine. Also we have considered a connection fault to the DC bus. In each case the assessment of power brought into play is checked. Simulation tests are established.

  4. Wind generation systems for remote communities: market assessment and guidelines for wind turbines selection

    International Nuclear Information System (INIS)

    Brothers, C.

    1993-06-01

    Wind technology and its market potential in remote communities of the Canadian North were discussed. These communities, unserviced by the main utility electricity grid, generate their own electricity using high quality, expensive diesel fuel to power diesel driven generators. The logistics of delivering fuel to these remote communities is an expensive operation. Wind resource in many of these communities is substantial and wind energy is seen as a prime candidate for supplying electricity to many potential sites in the Arctic and also areas in Quebec and Newfoundland. However, the severe service (i.e., cold climate, remote locations with limited facilities) requires special considerations to ensure that equipment installed performs reliably. This report described some demonstration projects in northern Canada over the last ten years, where an understanding of the special needs of wind turbines in remote areas has been developed. A guide which assessed the suitability of wind turbines for Arctic applications was included to assist organisations in preparing requirements to be used in acquiring wind turbines for use in cold regions. Refs., tabs., figs

  5. Rogue waves generated through quantum chaos

    KAUST Repository

    Liu, Changxu

    2013-05-01

    Rouge waves, or freak waves, are extreme events that manifest themselves with the formation of waves with giant amplitude. One of the distinctive features of their appearance is an anomalous amplitude probability distribution, which shows significant deviations from the classical Rayleigh statistics [1]. Initially observed in the context of oceanography, rogue waves have been extensively studied in Optics where their observation has been reported in nonlinear optical fibers [2] and laser systems [3]. © 2013 IEEE.

  6. Rogue waves generated through quantum chaos

    KAUST Repository

    Liu, Changxu; Di Falco, Andrea; Krauss, Thomas F.; Fratalocchi, Andrea

    2013-01-01

    Rouge waves, or freak waves, are extreme events that manifest themselves with the formation of waves with giant amplitude. One of the distinctive features of their appearance is an anomalous amplitude probability distribution, which shows significant deviations from the classical Rayleigh statistics [1]. Initially observed in the context of oceanography, rogue waves have been extensively studied in Optics where their observation has been reported in nonlinear optical fibers [2] and laser systems [3]. © 2013 IEEE.

  7. Effect of wind waves on air-sea gas exchange: proposal of an overall CO2 transfer velocity formula as a function of breaking-wave parameter

    International Nuclear Information System (INIS)

    Zhao, D.; Suzuki, Y.; Komori, S.

    2003-01-01

    A new formula for gas transfer velocity as a function of the breaking-wave parameter is proposed based on correlating gas transfer with whitecap coverage. The new formula for gas transfer across an air-sea interface depends not only on wind speed but also on wind-wave state. At the same wind speed, a higher gas transfer velocity will be obtained for a more developed wind-sea, which is represented by a smaller spectral peak frequency of wind waves. We suggest that the large uncertainties in the traditional relationship of gas transfer velocity with wind speed be ascribed to the neglect of the effect of wind waves. The breaking-wave parameter can be regarded as a Reynolds number that characterizes the intensity of turbulence associated with wind waves in the downward-bursting boundary layer (DBBL). DBBL provides an effective way to exchange gas across the air-sea interface, which might be related to the surface renewal

  8. Floating wind generators offshore wind farm: Implications for structural loads and control actions

    International Nuclear Information System (INIS)

    Garcia, E.; Morant F, Quiles E.; Correcher, A.

    2009-01-01

    This paper describes the work currently carried out in the design of floating wind generators and their involvement in the future development of power generation in marine farms in depths exceeding 20 m. We discuss the main issues to be taken into account in the design of floating platforms, including the involvement of structural loads they bear. Also from a standpoint of control engineering are discussed strategies to reduce structural loads such a system to ensure adequate durability and therefore ensuring their economic viability. Finally, the abstract modeling tools for floating wind turbines that can be used in both structural design and the design of appropriate control algorithms

  9. Modelling wind speed parameters for computer generation of wind speed in Flanders. A case study using small wind turbines in an urban environment

    Energy Technology Data Exchange (ETDEWEB)

    Gay, Michael; Dessel, Michel van [Lessius Mechelen, Campus De Nayer (Belgium). Dept. of Applied Engineering; Driesen, Johan [Leuven Univ. (Belgium). Dept. of Electrical Engineering / ESAT

    2012-07-01

    The calculation of wind energy parameters is made for small wind turbines on moderate height in a suburban environment. After using the measured data, the same parameters were calculated using first order Markov chain computer generated data. Some characteristics of the wind and the wind power were preserved using Markov, other were not. (orig.)

  10. Wind-Wave Effects on Vertical Mixing in Chesapeake Bay, USA: comparing observations to second-moment closure predictions.

    Science.gov (United States)

    Fisher, A. W.; Sanford, L. P.; Scully, M. E.

    2016-12-01

    Coherent wave-driven turbulence generated through wave breaking or nonlinear wave-current interactions, e.g. Langmuir turbulence (LT), can significantly enhance the downward transfer of momentum, kinetic energy, and dissolved gases in the oceanic surface layer. There are few observations of these processes in the estuarine or coastal environments, where wind-driven mixing may co-occur with energetic tidal mixing and strong density stratification. This presents a major challenge for evaluating vertical mixing parameterizations used in modeling estuarine and coastal dynamics. We carried out a large, multi-investigator study of wind-driven estuarine dynamics in the middle reaches of Chesapeake Bay, USA, during 2012-2013. The center of the observational array was an instrumented turbulence tower with both atmospheric and marine turbulence sensors as well as rapidly sampled temperature and conductivity sensors. For this paper, we examined the impacts of surface gravity waves on vertical profiles of turbulent mixing and compared our results to second-moment turbulence closure predictions. Wave and turbulence measurements collected from the vertical array of Acoustic Doppler Velocimeters (ADVs) provided direct estimates of the dominant terms in the TKE budget and the surface wave field. Observed dissipation rates, TKE levels, and turbulent length scales are compared to published scaling relations and used in the calculation of second-moment nonequilibrium stability functions. Results indicate that in the surface layer of the estuary, where elevated dissipation is balanced by vertical divergence in TKE flux, existing nonequilibrium stability functions underpredict observed eddy viscosities. The influences of wave breaking and coherent wave-driven turbulence on modeled and observed stability functions will be discussed further in the context of turbulent length scales, TKE and dissipation profiles, and the depth at which the wave-dominated turbulent transport layer

  11. Generation and Limiters of Rogue Waves

    Science.gov (United States)

    2014-06-01

    Jacobs, 7320 Ruth H. Preller, 7300 1231 1008.3 E. R. Franchi , 7000 Erick Rogers, 7322 1. REFERENCES AND ENCLOSURES 2. TYPE OF PUBLICATION OR...wave heights do not grow unlimited. With massive amount of global wave observations available nowadays, wave heights much in excess of 30m have never

  12. Stochastic generation of continuous wave spectra

    DEFF Research Database (Denmark)

    Trulsen, J.; Dysthe, K. B.; Pécseli, Hans

    1983-01-01

    Wave packets of electromagnetic or Langmuir waves trapped in a well between oscillating reflectors are considered. An equation for the temporal evolution of the probability distribution for the carrier wave number is derived, and solved analytically in terms of moments in the limits of long...

  13. Wave loads on offshore wind turbines: Accurate tools and structural response

    DEFF Research Database (Denmark)

    Bredmose, Henrik

    2014-01-01

    Can the design models for offshore wind turbine wave loads be improved? And how will that change the overall load picture? Core questions of the Wave Loads project which was finalised in 2013 with two PhD theses, response calculations for jackets and monopiles, a detailed set of experiments and a3D...... coupled CFD wave solver...

  14. Multi-Pole HTS Generators for Direct Drive Wind Turbines

    DEFF Research Database (Denmark)

    Jensen, Bogi Bech; Abrahamsen, Asger Bech; Seiler, Eugen

    or the performance of the coated conductor has to improve significantly (by a factor of 10 or more) in order for HTS generators to become feasible in direct drive offshore wind turbines. This price/performance improvement is not unrealistic in the coming decade. Additionally the reliability of such machines...

  15. Induction Generators for Direct-Drive Wind Turbines

    DEFF Research Database (Denmark)

    Henriksen, Matthew Lee; Jensen, Bogi Bech

    2011-01-01

    This paper considers the use of a squirrel cage induction generator for a direct-drive wind turbine. Advantages of this topology include a simple/rugged construction, and no need for permanent magnets. A major focus of this paper is the choice of an appropriate pole number. An iterative, analytical...

  16. Simulations of wind turbine rotor with vortex generators

    DEFF Research Database (Denmark)

    Sørensen, Niels N.; Zahle, Frederik; Sørensen, Niels N.

    2016-01-01

    This work presents simulations of the DTU 10MW wind turbine rotor equipped with vortex generators (VGs) on the inner part of the blades. The objective is to study the influence of different VG configurations on rotor performance and in particular to investigate the radial dependence of VGs, i...

  17. Optimal Excitation Controller Design for Wind Turbine Generator

    Directory of Open Access Journals (Sweden)

    A. K. Boglou

    2011-01-01

    Full Text Available An optimal excitation controller design based on multirate-output controllers (MROCs having a multirate sampling mechanismwith different sampling period in each measured output of the system is presented. The proposed H∞ -control techniqueis applied to the discrete linear open-loop system model which represents a wind turbine generator supplying an infinite busthrough a transmission line.

  18. Computation of Superconducting Generators for Wind Turbine Applications

    DEFF Research Database (Denmark)

    Rodriguez Zermeno, Victor Manuel

    The idea of introducing a superconducting generator for offshore wind turbine applications has received increasing support. It has been proposed as a way to meet energy market requirements and policies demanding clean energy sources in the near future. However, design considerations have to take......, to the actual generators in the KW (MW) class with an expected cross section in the order of decimeters (meters). This thesis work presents cumulative results intended to create a bottom-up model of a synchronous generator with superconducting rotor windings. In a first approach, multiscale meshes with large...... of the generator including ramp-up of rotor coils, load connection and change was simulated. Hence, transient hysteresis losses in the superconducting coils were computed. This allowed addressing several important design and performance issues such as critical current of the superconducting coils, electric load...

  19. The influence of solar wind variability on magnetospheric ULF wave power

    International Nuclear Information System (INIS)

    Pokhotelov, D.; Rae, I.J.; Mann, I.R.

    2015-01-01

    Magnetospheric ultra-low frequency (ULF) oscillations in the Pc 4-5 frequency range play an important role in the dynamics of Earth's radiation belts, both by enhancing the radial diffusion through incoherent interactions and through the coherent drift-resonant interactions with trapped radiation belt electrons. The statistical distributions of magnetospheric ULF wave power are known to be strongly dependent on solar wind parameters such as solar wind speed and interplanetary magnetic field (IMF) orientation. Statistical characterisation of ULF wave power in the magnetosphere traditionally relies on average solar wind-IMF conditions over a specific time period. In this brief report, we perform an alternative characterisation of the solar wind influence on magnetospheric ULF wave activity through the characterisation of the solar wind driver by its variability using the standard deviation of solar wind parameters rather than a simple time average. We present a statistical study of nearly one solar cycle (1996-2004) of geosynchronous observations of magnetic ULF wave power and find that there is significant variation in ULF wave powers as a function of the dynamic properties of the solar wind. In particular, we find that the variability in IMF vector, rather than variabilities in other parameters (solar wind density, bulk velocity and ion temperature), plays the strongest role in controlling geosynchronous ULF power. We conclude that, although time-averaged bulk properties of the solar wind are a key factor in driving ULF powers in the magnetosphere, the solar wind variability can be an important contributor as well. This highlights the potential importance of including solar wind variability especially in studies of ULF wave dynamics in order to assess the efficiency of solar wind-magnetosphere coupling.

  20. Feasibility study of 5MW superconducting wind turbine generator

    DEFF Research Database (Denmark)

    Abrahamsen, Asger Bech; Jensen, Bogi Bech; Seiler, E.

    2011-01-01

    The feasibility of installing a direct drive superconducting generator in the 5MW reference offshore wind turbine of the National Renewable Energy Laboratory (NREL) has been examined. The engineering current densities Je obtained in a series of race track coils have been combined with magnetization...... measurements to estimate the properties of suitable field coils for a synchronous generator, which is more light weight than the conventional used combination of a gear box and a fast rotating generator. An analytical model and finite element simulations have been used to estimate the active mass of generators...

  1. Heat wave generates questions about Ontario's generation capacity

    International Nuclear Information System (INIS)

    Horne, D.

    2005-01-01

    Concerns regarding Ontario's power generation capacity were raised following a major blackout which occurred in August 2003. Power demand reached 26,170 MW during the weeks leading to the blackout, forcing the Independent Electricity System Operator (IESO) to ask residents to reduce electricity use during the day. The grid operator had also issued a forecast that Toronto could face rolling blackouts during times of heavy power demand. Ontario power consumption records were set in June and July of 2003 due to a heat wave, with hourly demand exceeding 25,000 MW on 53 occasions. Ontario was forced to import up to 3,400 MW (13 per cent of its power needs) from neighbouring provinces and the United States. During that period, the price of power had risen sharply to over 30 cents a kilowatt hour, although household consumers were still charged in the 5 to 10 cent range per kilowatt hour. However, it was noted that taxpayers will eventually bear the cost of importing power. The IESO noted that importing electricity is cheaper than the generation available in Ontario and that it is more economical to import, based on the market clearing price of all generators. In 2004, the IESO purchased 6 per cent of their electricity from the United States. That figure is expected to increase for 2005. Ontario generators produced 26.9 million MWh more in the summer of 2005 than during the same period in 2004 to meet electricity demand levels. It was noted that although importing power presently meets peak demand, the IESO agrees there is a need for new generation within Ontario. In addition to restarting Ontario's Pickering and Bruce nuclear facilities, more than 3,300 MW of new gas-fired generation is under construction or approved, and more than 9,000 MW are in various stages of approval. This paper discussed the effect of high energy costs on industry and Ontario's ability to meet future electricity demand in comparison to neighbouring jurisdictions. Issues regarding grid maintenance

  2. Concentrated Windings in Compact Permanent Magnet Synchronous Generators: Managing Efficiency

    Directory of Open Access Journals (Sweden)

    Olivier Barré

    2016-01-01

    Full Text Available In electric power generation, customers want generators with high efficiency. Nowadays, modern turbo-generators have efficiencies greater than 98%. Although this amount should not be obtained for all kind of machines, efficiency will remain one of the main parameters for customer choice. Efficiency is also linked to the life of the machine: the higher the efficiency is, the longer the machine’s lifetime. During the past decade, new forms of energy production have appeared and generators have been developed to fit well into this market. For example, wind generators evolved towards permanent magnet generators having high polarity and running at low speed. Nevertheless, their structure is not fixed. An industrial company has built a prototype of such a generator which uses fractional-slot concentrated-windings (FSCW. This kind of winding is not the structure used by default in such electrical machines. Another field of interest is in autonomous generators which can be used on boats. Even if everyone has in mind large merchant ships, we must not forget smaller ships, such as fishing boats and short-range cruise ships, which spend the most of their time near the coast. This kind of ship does nothave large areas for installing the electric generation or the electric propulsion. It is the reason why, in this article, we focus on the efficiency of machines using fractional-slot concentrated-windings. In many publications which compare performances between distributed and concentrated windings, the result is almost the same. The efficiency of FSCW is not as high as the efficiency associated to the machines which are using distributed windings. Design methods have to be redrawn to integrate, as soon as possible, the loss mitigation in order to provide the best efficiency in power conversion. The following discussion, step by step, introduces the loss mitigation in every part of a machine using FSCW. To close the discussion, a design is produced and it

  3. A stationary phase solution for mountain waves with application to mesospheric mountain waves generated by Auckland Island

    Science.gov (United States)

    Broutman, Dave; Eckermann, Stephen D.; Knight, Harold; Ma, Jun

    2017-01-01

    A relatively general stationary phase solution is derived for mountain waves from localized topography. It applies to hydrostatic, nonhydrostatic, or anelastic dispersion relations, to arbitrary localized topography, and to arbitrary smooth vertically varying background temperature and vector wind profiles. A simple method is introduced to compute the ray Jacobian that quantifies the effects of horizontal geometrical spreading in the stationary phase solution. The stationary phase solution is applied to mesospheric mountain waves generated by Auckland Island during the Deep Propagating Gravity Wave Experiment. The results are compared to a Fourier solution. The emphasis is on interpretations involving horizontal geometrical spreading. The results show larger horizontal geometrical spreading for nonhydrostatic waves than for hydrostatic waves in the region directly above the island; the dominant effect of horizontal geometrical spreading in the lower ˜30 km of the atmosphere, compared to the effects of refraction and background density variation; and the enhanced geometrical spreading due to directional wind in the approach to a critical layer in the mesosphere.

  4. An innovative approach for energy generation from waves

    Energy Technology Data Exchange (ETDEWEB)

    Al-Habaibeh, A. [Advanced Design and Manufacturing Engineering Centre, School of Architecture, Design and the Built Environment, Nottingham Trent University (United Kingdom); Su, D. [School of Architecture, Design and the Built Environment, Nottingham Trent University (United Kingdom); McCague, J. [Technical Director, Ocean Navitas Ltd., Lincolnshire (United Kingdom); Knight, A. [Marketing and Communications Manager, Ocean Navitas Ltd., Lincolnshire (United Kingdom)

    2010-08-15

    Sustainable energy generation is becoming increasingly important due to the expected limitations in current energy resources and to reduce pollution. Wave energy generation has seen significant development in recent years. This paper describes an innovative system for generating energy from wave power. A complete description of the system is presented including the general concept, configurations, mechanical design, electrical system, simulation techniques and expected power output of the system. The results from the hydraulic linear wave simulator, using a real wave profiles captured at a location in the UK using an ultrasound system, it was seen that a {+-}0.8 m wave at 10 s time period, produced a conditioned power output of approximately 22 kW at optimum load conditions for the tested 3-phase 44 kW permanent magnet generator type STK500. The results indicate that this new technology could provide an efficient and low cost method of generating electricity from waves. (author)

  5. An innovative approach for energy generation from waves

    International Nuclear Information System (INIS)

    Al-Habaibeh, A.; Su, D.; McCague, J.; Knight, A.

    2010-01-01

    Sustainable energy generation is becoming increasingly important due to the expected limitations in current energy resources and to reduce pollution. Wave energy generation has seen significant development in recent years. This paper describes an innovative system for generating energy from wave power. A complete description of the system is presented including the general concept, configurations, mechanical design, electrical system, simulation techniques and expected power output of the system. The results from the hydraulic linear wave simulator, using a real wave profiles captured at a location in the UK using an ultrasound system, it was seen that a ±0.8 m wave at 10 s time period, produced a conditioned power output of approximately 22 kW at optimum load conditions for the tested 3-phase 44 kW permanent magnet generator type STK500. The results indicate that this new technology could provide an efficient and low cost method of generating electricity from waves.

  6. Stochastic model for joint wave and wind loads on offshore structures

    DEFF Research Database (Denmark)

    Ditlevsen, Ove Dalager

    2002-01-01

    _s,T_z)$ from the North Sea a well fitting joint distribution of $(H_s,T_z)$ is obtained as a so-called Nataf model. Since the wave field is wind driven, there is a correlation between the time averaged wind velocity pressure $Q$ and the characteristic wave height in the stationary situation. Using the Poisson...... process model to concentrate on those load events that are of importance for the evaluation of the safety of the structure, that is, events with $Q$ larger than some threshold $q_0$, available information about the wind velocity pressure distributionin high wind situations can be used to formulate a Nataf...

  7. Extended onshore control of a floating wind turbine with wave disturbance reduction

    DEFF Research Database (Denmark)

    Christiansen, S.; Knudsen, T.; Bak, Thomas

    2014-01-01

    Reaching for higher wind resources floating wind turbines are being investigated. Wave induced loads significantly increase for floating wind turbines, and applying conventional onshore control strategies to floating wind turbines has been shown to impose negative damped oscillations in fore......-aft due to the low natural frequency of the floating structure. We suggest a control loop extension of the onshore controller which stabilizes the system and reduces the wave disturbance. The result is improved performance in power fluctuations, blade pitch activity, and platform oscillations...

  8. Enhancing Wave Energy Competitiveness through Co-Located Wind and Wave Energy Farms. A Review on the Shadow Effect

    OpenAIRE

    Sharay Astariz; Gregorio Iglesias

    2015-01-01

    Wave energy is one of the most promising alternatives to fossil fuels due to the enormous available resource; however, its development may be slowed as it is often regarded as uneconomical. The largest cost reductions are expected to be obtained through economies of scale and technological progress. In this sense, the incorporation of wave energy systems into offshore wind energy farms is an opportunity to foster the development of wave energy. The synergies between both renewables can be rea...

  9. The Triple Spar campaign: Model tests of a 10MW floating wind turbine with waves, wind and pitch control

    DEFF Research Database (Denmark)

    Bredmose, Henrik; Lemmer, F.; Borg, Michael Borg

    2017-01-01

    Results of a test campaign for a floating wind turbine in simultaneous wind and wave forcing at scale 1:60 are presented. The floater is the Triple Spar floater, a hybrid between a spar buoy and a semi submersible tri-floater, tested here for the first time. The turbine is a model scale version...... of the DTU 10 MW reference wind turbine, which, also for the first time, is tested with active blade pitch control. The tests focus on the effects of aerodynamic damping and interaction effects between the wind forcing, wave forcing and the blade pitch control algorithm. Special focus is devoted...... to the instability of the platform pitch natural mode, that can occur if a standard land-based controller is applied....

  10. French wind power generation programme EOLE 2005 - first results

    Energy Technology Data Exchange (ETDEWEB)

    Laali, A.R. [Electricite de France (EDF), Chatou (France); Benard, M. [Electricite de France (EDF), Paris (France)

    1997-12-31

    EOLE 2005 has been launched in July 1996 by the French Ministry of Industry, Electricite de France and ADEME (Agency for Environment and Energy Management). The Ministries of Research and Environment are participating also in this programme. The purpose is to create an initial market in France for wind power generation in order to evaluate the cost-effectiveness and the competitiveness of the wind energy compared to other energy sources by 2005. The installed capacity will reach at least 250 MW and possibly 500 MW.

  11. Wind energy-hydrogen storage hybrid power generation

    Energy Technology Data Exchange (ETDEWEB)

    Wenjei Yang; Orhan Aydin [University of Michigan, Ann Arbor, MI (United States). Dept. of Mechanical Engineering and Applied Mechanics

    2001-07-01

    In this theoretical investigation, a hybrid power generation system utilizing wind energy and hydrogen storage is presented. Firstly, the available wind energy is determined, which is followed by evaluating the efficiency of the wind energy conversion system. A revised model of windmill is proposed from which wind power density and electric power output are determined. When the load demand is less than the output of the generation, the excess electric power is relayed to the electrolytic cell where it is used to electrolyse the de-ionized water. Hydrogen thus produced can be stored as hydrogen compressed gas or liquid. Once the hydrogen is stored in an appropriate high-pressure vessel, it can be used in a combustion engine, fuel cell, or burned in a water-cooled burner to produce a very high-quality steam for space heating, or to drive a turbine to generate electric power. It can also be combined with organic materials to produce synthetic fuels. The conclusion is that the system produces no harmful waste and depletes no resources. Note that this system also works well with a solar collector instead of a windmill. (author)

  12. Gravitational wave generation by stellar core collapse

    International Nuclear Information System (INIS)

    Moore, T.A.

    1981-01-01

    Stars which have masses greater than 5 to 8 solar masses are thought to undergo a stage of catastrophic core collapse and subsequent supernova explosion at the end of their lives. If the core is not spherically symmetric, the bounce which halts its collapse at transnuclear densities will generate a pulse of gravitational waves. This thesis presents a fully relativistic model of core collapse which treats deviations from spherical symmetry as small perturbations on a spherical background. This model may be used to predict qualitative and quantitative features of the gravitational radiation emitted by stellar cores with odd-parity, axisymmetric fluid perturbations, and represents a first step in the application of perturbative methods to more general asymmetries. The first chapter reviews the present consensus on the physics of core collapse and outlines the important features, assumptions, and limitations of the model. A series of model runs are presented and discussed. Finally, several proposals for future research are presented. Subsequent chapters explore in detail the mathematical features of the present model and its realization on the computer

  13. MPPT for PM wind generator using gradient approximation

    International Nuclear Information System (INIS)

    Hong, Y.-Y.; Lu, S.-D.; Chiou, C.-S.

    2009-01-01

    This paper applies new maximum-power-point tracking (MPPT) algorithms to a wind-turbine generator system (WTGS). In this paper, the WTGS is a direct-drive system and includes the wind-turbine, permanent-magnet (PM) synchronous generator, three-phase full bridge rectifier, buck-boost converter and load. The new MPPT method uses gradient approximation (GA) algorithm. Three methods based on GA for achieving MPPT are discussed in this paper: (1) full-sensor control with anemometer and tachometer, (2) rule-based method and (3) adaptive duty cycle method. The third method has merits of no PID parameters, proportional constant, anemometer, tachometer and characteristics of WTGS required. This method enables the permanent-magnet synchronous generator (PMSG) to operate at variable speeds to achieve good performance. Simulation results show that the tip-speed ratio (TSR) and power coefficient obtained by the adaptive duty cycle method with GA can be almost identical to the optimal values

  14. Propagation of nonlinear ion acoustic wave with generation of long-wavelength waves

    International Nuclear Information System (INIS)

    Ohsawa, Yukiharu; Kamimura, Tetsuo

    1978-01-01

    The nonlinear propagation of the wave packet of an ion acoustic wave with wavenumber k 0 asymptotically equals k sub(De) (the electron Debye wavenumber) is investigated by computer simulations. From the wave packet of the ion acoustic wave, waves with long wavelengths are observed to be produced within a few periods for the amplitude oscillation of the original wave packet. These waves are generated in the region where the original wave packet exists. Their characteristic wavelength is of the order of the length of the wave packet, and their propagation velocity is almost equal to the ion acoustic speed. The long-wavelength waves thus produced strongly affect the nonlinear evolution of the original wave packet. (auth.)

  15. Coastal and offshore wind energy generation: is it environmentally benign?

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, J. C.; Elliott, M.; Cutts, N. D.; Mander, L.; Mendao, V.; Perez-Dominguez, R.; Phelps, A. [Institute of Estuarine and Coastal Studies, University of Hull, Hull, HU6 7RX (United Kingdom); Wilson, J. C. [Amec, Booths Park, Chelford Road, Knutsford, Cheshire, WA16 8QZ (United Kingdom); Mendao, V. [Projecto Delfim, Centro Portugues de Estudo dos Mamiferos Marinhos, Rua Alto do Duque, 45, 1400-009 Lisboa (Portugal)

    2010-07-15

    Offshore and coastal wind power is one of the fastest growing industries in many areas, especially those with shallow coastal regions due to the preferable generation conditions available in the regions. As with any expanding industry, there are concerns regarding the potential environmental effects which may be caused by the installation of the offshore wind turbines and their associated infrastructure, including substations and subsea cables. These include the potential impacts on the biological, physical and human environments. This review discusses in detail the potential impacts arising from offshore wind farm construction, and how these may be quantified and addressed through the use of conceptual models. It concludes that while not environmentally benign, the environmental impacts are minor and can be mitigated through good siting practices. In addition, it suggests that there are opportunities for environmental benefits through habitat creation and conservation protection areas. (authors)

  16. A multi-decadal wind-wave hindcast for the North Sea 1949-2014: coastDat2

    Science.gov (United States)

    Groll, Nikolaus; Weisse, Ralf

    2017-12-01

    Long and consistent wave data are important for analysing wave climate variability and change. Moreover, such wave data are also needed in coastal and offshore design and for addressing safety-related issues at sea. Using the third-generation spectral wave model WAM a multi-decadal wind-wave hindcast for the North Sea covering the period 1949-2014 was produced. The hindcast is part of the coastDat database representing a consistent and homogeneous met-ocean data set. It is shown that despite not being perfect, data from the wave hindcast are generally suitable for wave climate analysis. In particular, comparisons of hindcast data with in situ and satellite observations show on average a reasonable agreement, while a tendency towards overestimation of the highest waves could be inferred. Despite these limitations, the wave hindcast still provides useful data for assessing wave climate variability and change as well as for risk analysis, in particular when conservative estimates are needed. Hindcast data are stored at the World Data Center for Climate (WDCC) and can be freely accessed using the doi:10.1594/WDCC/coastDat-2_WAM-North_Sea Groll and Weisse(2016) or via the coastDat web-page http://www.coastdat.de.

  17. Extreme Value Predictions for Wave- and Wind-induced Loads on Floating Offshore Wind Turbines using FORM

    DEFF Research Database (Denmark)

    Joensen, Sunvard; Jensen, Jørgen Juncher; Mansour, Alaa E.

    2007-01-01

    duration of the time domain simulations needed (typically 60-300s to cover the hy-drodynamic memory effects in the response) the calcu-lation of the mean out-crossing rates of a given response are very fast. Thus complicated non-linear effects can be included. The FORM analysis also identifies the most...... probable wave episodes leading to given re-sponses. As an example the motions of floating foundations for offshore wind turbines are analysed taking into consid-eration both the wave and wind induced loads and con-sidering different mooring systems. The possible large horizontal motions make it important...

  18. Feasibility study of wind-generated electricity for rural applications in southwestern Ohio

    Science.gov (United States)

    Kohring, G. W.

    The parameters associated with domestic production of wind generated electricity for direct use by small farms and rural homes in the southwestern Ohio region are discussed. The project involves direct utility interfaced electricity generation from a horizontal axis, down-wind, fixed pitch, wind powered induction generator system. Goals of the project are to determine: the ability to produce useful amounts of domestic wind generated electricity in the southwestern Ohio region; economic justification for domestic wind generated electrical production; and the potential of domestic wind generated electricity for reducing dependence on non-renewable energy resources in the southwestern Ohio region.

  19. Design Tool for Direct Drive Wind Turbine Generators

    DEFF Research Database (Denmark)

    Leban, Krisztina Monika

    . A comparison of the selected machine types in view of up-scaling to 20 [MW] was performed. As an example fitness criterion, the use of active materials for the generators was considered. Based on this, suggestions for 20 [MW] generators were made. The results are discussed and future work, directions......The current work offers a comparison of the proposed machine geometries for 6 [MW] direct drive wind generator candidates with the prospective of up scaling to 20MW. The suggestions are based on a design tool especially built for this investigation. The in-built flexibility of the design tool gives...

  20. Effect of wind turbine generator model and siting on wind power changes out of large WECS arrays

    Science.gov (United States)

    Schleuter, R. A.; Park, G. L.; Lotfalian, M.; Dorsey, J.; Shayanfar, H.

    1981-01-01

    Methods of reducing the WECS generation change through selection of the wind turbine model for each site, selection of an appropriate siting configuration, and wind array controls are discussed. An analysis of wind generation change from an echelon and a farm for passage of a thunderstorm is presented. Reduction of the wind generation change over ten minutes is shown to reduce the increase in spinning reserve, unloadable generation and load following requirements on unit commitment when significant WECS generation is present and the farm penetration constraint is satisfied. Controls on the blade pitch angle of all wind turbines in an array or a battery control are shown to reduce both the wind generation change out of an array and the effective farm penetration in anticipation of a storm so that the farm penetration constraint may be satisfied.

  1. Beat-wave generation of plasmons in semiconductor plasmas

    International Nuclear Information System (INIS)

    Berezhiani, V.I.; Mahajan, S.M.

    1995-08-01

    It is shown that in semiconductor plasmas, it is possible to generate large amplitude plasma waves by the beating of two laser beams with frequency difference close to the plasma frequency. For narrow gap seimconductors (for example n-type InSb), the system can simulate the physics underlying beat wave generation in relativistic gaseous plasmas

  2. Beat-wave generation of plasmons in semiconductor plasmas

    International Nuclear Information System (INIS)

    Berezhiani, V.I.; Mahajan, S.M.

    1995-08-01

    It is shown that in semiconductor plasmas, it is possible to generate large amplitude plasma waves by the beating of two laser beams with frequency difference close to the plasma frequency. For narrow gap semiconductor (for example n-type InSb), the system can simulate the physics underlying beat wave generation in relativistic gaseous plasmas. (author). 7 refs

  3. The Red Sea: A Natural Laboratory for Wind and Wave Modeling

    KAUST Repository

    Langodan, Sabique; Cavaleri, Luigi; Viswanadhapalli, Yesubabu; Hoteit, Ibrahim

    2014-01-01

    The Red Sea is a narrow, elongated basin that is more than 2000km long. This deceivingly simple structure offers very interesting challenges for wind and wave modeling, not easily, if ever, found elsewhere. Using standard meteorological products and local wind and wave models, this study explores how well the general and unusual wind and wave patterns of the Red Sea could be reproduced. The authors obtain the best results using two rather opposite approaches: the high-resolution Weather Research Forecasting (WRF) local model and the slightly enhanced surface winds from the global European Centre for Medium-Range Weather Forecasts model. The reasons why these two approaches produce the best results and the implications on wave modeling in the Red Sea are discussed. The unusual wind and wave patterns in the Red Sea suggest that the currently available wave model source functions may not properly represent the evolution of local fields. However, within limits, the WAVEWATCH III wave model, based on Janssen's and also Ardhuin's wave model physics, provides very reasonable results in many cases. The authors also discuss these findings and outline related future work.

  4. The Red Sea: A Natural Laboratory for Wind and Wave Modeling

    KAUST Repository

    Langodan, Sabique

    2014-12-01

    The Red Sea is a narrow, elongated basin that is more than 2000km long. This deceivingly simple structure offers very interesting challenges for wind and wave modeling, not easily, if ever, found elsewhere. Using standard meteorological products and local wind and wave models, this study explores how well the general and unusual wind and wave patterns of the Red Sea could be reproduced. The authors obtain the best results using two rather opposite approaches: the high-resolution Weather Research Forecasting (WRF) local model and the slightly enhanced surface winds from the global European Centre for Medium-Range Weather Forecasts model. The reasons why these two approaches produce the best results and the implications on wave modeling in the Red Sea are discussed. The unusual wind and wave patterns in the Red Sea suggest that the currently available wave model source functions may not properly represent the evolution of local fields. However, within limits, the WAVEWATCH III wave model, based on Janssen\\'s and also Ardhuin\\'s wave model physics, provides very reasonable results in many cases. The authors also discuss these findings and outline related future work.

  5. Towards the best approach for wind wave modelling in the Red Sea

    KAUST Repository

    Langodan, Sabique; Cavaleri, Luigi; Viswanadhapalli; Viswanadhapalli, Yesubabu; Hoteit, Ibrahim

    2015-01-01

    orography. The Red Sea is an extreme example in this respect, especially because of its long and narrow shape. This deceivingly simple domain offers very interesting challenges for wind and wave modeling, not easily, if ever, found elsewhere. Depending

  6. Experimental and Theoretical Analysis of a Combined Floating Wave and Wind Energy Conversion Platform

    DEFF Research Database (Denmark)

    Yde, Anders; Pedersen, Mads Mølgaard; Bellew, Sarah Bellew

    This report presents results from the PSO project 2011-1-10668 entitled Poseidon 2. The project is a continuation of the previous PSO project entitled Aero-Hydro-Elastic Simulation Platform for Wave Energy Systems and floating Wind Turbines. Floating Power Plant has developed the technology...... for a novel, floating, wave- and wind-energy hybrid device. To test the technology they have scaled the design to P37, a 37 m wide test platform that has been undergoing offshore testing for four complete test phases (totaling more than 2 years). The test platform provides electricity to the grid from both...... wind and wave energy, however its purpose is purely for research and development. The PSO project has equipped the platform with comprehensive measurements equipment for measuring platform motion, wave and wind conditions and turbine loads. Data from the test periods has been used for evaluating...

  7. The Red Sea: An Arena for Wind-Wave Modeling in Enclosed Seas

    KAUST Repository

    Langodan, Sabique

    2016-01-01

    weather and climate is crucial for a wide range of applications, including oceanographic studies, maritime activities and ocean engineering. Despite being one of the important world shipping routes, the wind-wave characteristics in the Red Sea are yet

  8. Real-Time Forecasting System of Winds, Waves and Surge in Tropical Cyclones

    National Research Council Canada - National Science Library

    Graber, Hans C; Donelan, Mark A; Brown, Michael G; Slinn, Donald N; Hagen, Scott C; Thompson, Donald R; Jensen, Robert E; Black, Peter G; Powell, Mark D; Guiney, John L

    2005-01-01

    The long-term goal of this partnership is to establish an operational forecasting system of the wind field and resulting waves and surge impacting the coastline during the approach and landfall of tropical cyclones...

  9. Real-Time Forecasting System of Winds, Waves and Surge in Tropical Cyclones

    National Research Council Canada - National Science Library

    Graber, Hans C; Donelan, Mark A; Brown, Michael G; Slinn, Donald N; Hagen, Scott C; Thompson, Donald R; Jensen, Robert E; Black, Peter G; Powell, Mark D; Guiney, John L

    2004-01-01

    The long-term goal of this partnership is to establish an operational forecasting system of the wind field and resulting waves and surge impacting the coastline during the approach and landfall of tropical cyclones...

  10. Real-Time Forecasting System of Winds, Waves and Surge in Tropical Cyclones

    National Research Council Canada - National Science Library

    Graber, Hans C; Donelan, Mark A; Brown, Michael G; Slinn, Donald N; Hagen, Scott C; Thompson, Donald R; Jensen, Robert E; Black, Peter G; Powell, Mark D; Guiney, John L; Cardone, Vincent J; Cox, Andrew T; Augustus, Ellsworth H; Colonnese, Christopher P

    2003-01-01

    The long-term goal of this partnership is to establish an operational forecasting system of the wind field and resulting waves and surge impacting the coastline during the approach and landfall of tropical cyclones...

  11. The influence of solar wind variability on magnetospheric ULF wave power

    Directory of Open Access Journals (Sweden)

    D. Pokhotelov

    2015-06-01

    Full Text Available Magnetospheric ultra-low frequency (ULF oscillations in the Pc 4–5 frequency range play an important role in the dynamics of Earth's radiation belts, both by enhancing the radial diffusion through incoherent interactions and through the coherent drift-resonant interactions with trapped radiation belt electrons. The statistical distributions of magnetospheric ULF wave power are known to be strongly dependent on solar wind parameters such as solar wind speed and interplanetary magnetic field (IMF orientation. Statistical characterisation of ULF wave power in the magnetosphere traditionally relies on average solar wind–IMF conditions over a specific time period. In this brief report, we perform an alternative characterisation of the solar wind influence on magnetospheric ULF wave activity through the characterisation of the solar wind driver by its variability using the standard deviation of solar wind parameters rather than a simple time average. We present a statistical study of nearly one solar cycle (1996–2004 of geosynchronous observations of magnetic ULF wave power and find that there is significant variation in ULF wave powers as a function of the dynamic properties of the solar wind. In particular, we find that the variability in IMF vector, rather than variabilities in other parameters (solar wind density, bulk velocity and ion temperature, plays the strongest role in controlling geosynchronous ULF power. We conclude that, although time-averaged bulk properties of the solar wind are a key factor in driving ULF powers in the magnetosphere, the solar wind variability can be an important contributor as well. This highlights the potential importance of including solar wind variability especially in studies of ULF wave dynamics in order to assess the efficiency of solar wind–magnetosphere coupling.

  12. Private wind powered electricity generators for industry in the UK

    Science.gov (United States)

    Thabit, S. S.; Stark, J.

    This paper investigates the impact of the provisions of the new Energy Act, 1983 on industrial wind-powered private generators of electricity and the effects of published tariffs on various industrial working patterns. Up to 30 percent savings can be achieved in annual electricity bill costs for an industrial generator/user of electricity working a single daily shift, if located in a favorable, 7 m/s mean annual wind speed regime. Variation of the availability charge between Electricity Boards about a base value of 0.70 pounds sterling/kVA was found to have insignificant (+ or - 1.3 percent) impact on total electricity bill costs. It was also shown that for industrial users of electricity, the simpler two-rate purchase terms were commercially adequate when compared with the four-rate alternative where expensive metering becomes necessary.

  13. Optimized Generator Designs for the DTU 10-MW Offshore Wind Turbine using GeneratorSE

    Energy Technology Data Exchange (ETDEWEB)

    Sethuraman, Latha; Maness, Michael; Dykes, Katherine

    2017-01-09

    Compared to land-based applications, offshore wind imposes challenges for the development of next generation wind turbine generator technology. Direct-drive generators are believed to offer high availability, efficiency, and reduced operation and maintenance requirements; however, previous research suggests difficulties in scaling to several megawatts or more in size. The resulting designs are excessively large and/or massive, which are major impediments to transportation logistics, especially for offshore applications. At the same time, geared wind turbines continue to sustain offshore market growth through relatively cheaper and lightweight generators. However, reliability issues associated with mechanical components in a geared system create significant operation and maintenance costs, and these costs make up a large portion of overall system costs offshore. Thus, direct-drive turbines are likely to outnumber their gear-driven counterparts for this market, and there is a need to review the costs or opportunities of building machines with different types of generators and examining their competitiveness at the sizes necessary for the next generation of offshore wind turbines. In this paper, we use GeneratorSE, the National Renewable Energy Laboratory's newly developed systems engineering generator sizing tool to estimate mass, efficiency, and the costs of different generator technologies satisfying the electromagnetic, structural, and basic thermal design requirements for application in a very large-scale offshore wind turbine such as the Technical University of Denmark's (DTU) 10-MW reference wind turbine. For the DTU reference wind turbine, we use the previously mentioned criteria to optimize a direct-drive, radial flux, permanent-magnet synchronous generator; a direct-drive electrically excited synchronous generator; a medium-speed permanent-magnet generator; and a high-speed, doubly-fed induction generator. Preliminary analysis of leveled costs of

  14. Optimized Generator Designs for the DTU 10-MW Offshore Wind Turbine using GeneratorSE: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Sethuraman, Latha; Maness, Michael; Dykes, Katherine

    2017-01-01

    Compared to land-based applications, offshore wind imposes challenges for the development of next generation wind turbine generator technology. Direct-drive generators are believed to offer high availability, efficiency, and reduced operation and maintenance requirements; however, previous research suggests difficulties in scaling to several megawatts or more in size. The resulting designs are excessively large and/or massive, which are major impediments to transportation logistics, especially for offshore applications. At the same time, geared wind turbines continue to sustain offshore market growth through relatively cheaper and lightweight generators. However, reliability issues associated with mechanical components in a geared system create significant operation and maintenance costs, and these costs make up a large portion of overall system costs offshore. Thus, direct-drive turbines are likely to outnumber their gear-driven counterparts for this market, and there is a need to review the costs or opportunities of building machines with different types of generators and examining their competitiveness at the sizes necessary for the next generation of offshore wind turbines. In this paper, we use GeneratorSE, the National Renewable Energy Laboratory's newly developed systems engineering generator sizing tool to estimate mass, efficiency, and the costs of different generator technologies satisfying the electromagnetic, structural, and basic thermal design requirements for application in a very large-scale offshore wind turbine such as the Technical University of Denmark's (DTU) 10-MW reference wind turbine. For the DTU reference wind turbine, we use the previously mentioned criteria to optimize a direct-drive, radial flux, permanent-magnet synchronous generator; a direct-drive electrically excited synchronous generator; a medium-speed permanent-magnet generator; and a high-speed, doubly-fed induction generator. Preliminary analysis of leveled costs of

  15. Removable bearing arrangement for a wind turbine generator

    Science.gov (United States)

    Bagepalli, Bharat Sampathkumaran; Jansen, Patrick Lee; Gadre, Aniruddha Dattatraya

    2010-06-15

    A wind generator having removable change-out bearings includes a rotor and a stator, locking bolts configured to lock the rotor and stator, a removable bearing sub-assembly having at least one shrunk-on bearing installed, and removable mounting bolts configured to engage the bearing sub-assembly and to allow the removable bearing sub-assembly to be removed when the removable mounting bolts are removed.

  16. Design of DOE facilities for wind-generated missiles

    International Nuclear Information System (INIS)

    Kuilanoff, G.; Drake, R.M.

    1991-01-01

    This paper presents criteria and procedures for the design of structures and components for wind-generated missiles. Methods for determining missile-induced loading, calculated structural response, performance requirements, and design considerations are covered. The presented criteria is applicable to Safety-Related concrete buildings as a whole and to all their exposed external components including walls, roofs, and supporting structural systems and elements

  17. Real Time Wave Forecasting Using Wind Time History and Genetic Programming

    Directory of Open Access Journals (Sweden)

    A.R. Kambekar

    2014-12-01

    Full Text Available The significant wave height and average wave period form an essential input for operational activities in ocean and coastal areas. Such information is important in issuing appropriate warnings to people planning any construction or instillation works in the oceanic environment. Many countries over the world routinely collect wave and wind data through a network of wave rider buoys. The data collecting agencies transmit the resulting information online to their registered users through an internet or a web-based system. Operational wave forecasts in addition to the measured data are also made and supplied online to the users. This paper discusses operational wave forecasting in real time mode at locations where wind rather than wave data are continuously recorded. It is based on the time series modeling and incorporates an artificial intelligence technique of genetic programming. The significant wave height and average wave period values are forecasted over a period of 96 hr in future from the observations of wind speed and directions extending to a similar time scale in the past. Wind measurements made by floating buoys at eight different locations around India over a period varying from 1.5 yr to 9.0 yr were considered. The platform of Matlab and C++ was used to develop a graphical user interface that will extend an internet based user-friendly access of the forecasts to any registered user of the data dissemination authority.

  18. Wave Run-Up on Cylindrical and Cone Shaped Foundations for Offshore Wind Turbines

    DEFF Research Database (Denmark)

    De Vos, Leen; Frigaard, Peter; De Rouck, Julien

    2007-01-01

    During the last decade, several offshore wind-farms were built and offshore wind energy promises to be a suitable alternative to provide green energy. However, there are still some engineering challenges in placing the foundations of offshore wind turbines. For example, wave run-up and wave impacts....... The results show that the shape of the foundation substantially affects the maximum run-up level, increasing the expected run-up value. A new relationship between the wave climate (regular and irregular waves) and the run-up is suggested. For this, the velocity stagnation head theory is adjusted and second...... order Stokes equations are used to calculate the wave kinematics in the crest. The variation of the run-up around the pile is measured and it is found that the position with the lowest run-up level is located under 135°, while the run-up at that position amounts to approximately 40% to 50...

  19. Time-Reversal Generation of Rogue Waves

    Science.gov (United States)

    Chabchoub, Amin; Fink, Mathias

    2014-03-01

    The formation of extreme localizations in nonlinear dispersive media can be explained and described within the framework of nonlinear evolution equations, such as the nonlinear Schrödinger equation (NLS). Within the class of exact NLS breather solutions on a finite background, which describe the modulational instability of monochromatic wave trains, the hierarchy of rational solutions localized in both time and space is considered to provide appropriate prototypes to model rogue wave dynamics. Here, we use the time-reversal invariance of the NLS to propose and experimentally demonstrate a new approach to constructing strongly nonlinear localized waves focused in both time and space. The potential applications of this time-reversal approach include remote sensing and motivated analogous experimental analysis in other nonlinear dispersive media, such as optics, Bose-Einstein condensates, and plasma, where the wave motion dynamics is governed by the NLS.

  20. Generation and Micro-scale Effects of Electrostatic Waves in an Oblique Shock

    Science.gov (United States)

    Goodrich, K.; Ergun, R.; Schwartz, S. J.; Newman, D.; Johlander, A.; Argall, M. R.; Wilder, F. D.; Torbert, R. B.; Khotyaintsev, Y. V.; Lindqvist, P. A.; Strangeway, R. J.; Russell, C. T.; Giles, B. L.; Gershman, D. J.; Burch, J. L.

    2017-12-01

    We present an analysis of large amplitude (>100 mV/m), high frequency (≤1 kHz), electrostatic waves observed by MMS during an oblique bow shock crossing event. The observed waves primarily consist of electrostatic solitary waves (ESWs) and oblique ion plasma waves (IPWs). ESWs typically include nonlinear structures such as double layers, ion phase-space holes, and electron phase-space holes. Oblique IPWs are observed to be similar to ion acoustic waves, but can propagate up to 70° from the ambient magnetic field direction. Both wave-modes, particularly IPWs, are observed to have very short wavelengths ( 100 m) and are highly localized. While such wave-modes have been previously observed in the terrestrial bow shock, instrumental constraints have limited detailed insight into their generation and their effect on their plasma shock environment. Analysis of this oblique shock event shows evidence that ESWs and oblique IPWs can be generated through field-aligned currents associated with magnetic turbulence and through a counterstreaming ion instability respectively. We also present evidence that this wave activity can facilitate momentum exchange between ion populations, resulting in deceleration of incoming solar wind, and localized electron heating.

  1. Lightweight MgB2 superconducting 10 MW wind generator

    Science.gov (United States)

    Marino, I.; Pujana, A.; Sarmiento, G.; Sanz, S.; Merino, J. M.; Tropeano, M.; Sun, J.; Canosa, T.

    2016-02-01

    The offshore wind market demands a higher power rate and more reliable turbines in order to optimize capital and operational costs. The state-of-the-art shows that both geared and direct-drive conventional generators are difficult to scale up to 10 MW and beyond due to their huge size and weight. Superconducting direct-drive wind generators are considered a promising solution to achieve lighter weight machines. This work presents an innovative 10 MW 8.1 rpm direct-drive partial superconducting generator using MgB2 wire for the field coils. It has a warm iron rotor configuration with the superconducting coils working at 20 K while the rotor core and the armature are at ambient temperature. A cooling system based on cryocoolers installed in the rotor extracts the heat from the superconducting coils by conduction. The generator's main parameters are compared against a permanent magnet reference machine, showing a significant weight and size reduction. The 10 MW superconducting generator concept will be experimentally validated with a small-scale magnetic machine, which has innovative components such as superconducting coils, modular cryostats and cooling systems, and will have similar size and characteristics as the 10 MW generator.

  2. Loss Minimizing Operation of Doubly Fed Induction Generator Based Wind Generation Systems Considering Reactive Power Provision

    DEFF Research Database (Denmark)

    Baohua, Zhang; Hu, Weihao; Chen, Zhe

    2014-01-01

    The paper deals with control techniques for minimizing the operating loss of doubly fed induction generator based wind generation systems when providing reactive power. The proposed method achieves its goal through controlling the rotor side q-axis current in the synchronous reference frame...

  3. Vibration monitoring of large generator stator and-winding

    International Nuclear Information System (INIS)

    Duffeau, F.; Bernard, P.

    1999-01-01

    Large generators of French Nuclear Power plants are equipped with a standardised vibration monitoring system. The first aim of these new systems is to protect the machines by generating alarms in the control room when predefined vibration thresholds have been over-passed. Secondly, this specially designed instrumentation permits to create a National data base allowing to compare different generators of the same technology. Additionally, statistical methods have been developed in order to 'guess' vibration level at several locations of the stator end-windings, depending on the actual operating parameters of the generator, i.e. reactive and active power load. So this paper presents the general concept of the vibration monitoring of EDF large generator stators and deals with a new method to predict vibrations in different locations under control. (authors)

  4. Crowbar System in Doubly Fed Induction Wind Generators

    Directory of Open Access Journals (Sweden)

    Maurício B. C. Salles

    2010-04-01

    Full Text Available In the last 15 years, the use of doubly fed induction machines in modern variable-speed wind turbines has increased rapidly. This development has been driven by the cost reduction as well as the low-loss generation of Insulated Gate Bipolar Transistors (IGBT. According to new grid code requirements, wind turbines must remain connected to the grid during grid disturbances. Moreover, they must also contribute to voltage support during and after grid faults. The crowbar system is essential to avoid the disconnection of the doubly fed induction wind generators from the network during faults. The insertion of the crowbar in the rotor circuits for a short period of time enables a more efficient terminal voltage control. As a general rule, the activation and the deactivation of the crowbar system is based only on the DC-link voltage level of the back-to-back converters. In this context, the authors discuss the critical rotor speed to analyze the instability of doubly fed induction generators during grid faults.

  5. Probabilistic Forecast of Wind Power Generation by Stochastic Differential Equation Models

    KAUST Repository

    Elkantassi, Soumaya

    2017-01-01

    Reliable forecasting of wind power generation is crucial to optimal control of costs in generation of electricity with respect to the electricity demand. Here, we propose and analyze stochastic wind power forecast models described by parametrized

  6. A novel excitation assistance switched reluctance wind power generator

    DEFF Research Database (Denmark)

    Liu, Xiao; Park, Kiwoo; Chen, Zhe

    2014-01-01

    The high inductance of a general switched reluctance generator (SRG) may prevent the excitation of the magnetic field from being quickly established enough, which may further limit the output power of the SRG. A novel excitation assistance SRG (EASRG) for wind power generation is proposed...... in this paper to solve the above problem. C-shape stator cores are employed in a modular design concept for quick maintenance or replacement, and a ring-shape excitation assistant coil is sandwiched in the space between the modular stator cores. The magnetization and torque characteristics are simulated by 3-D...

  7. HTS technology - Generating the future of offshore wind power

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, Jens

    2010-09-15

    Superconductive generator design is going to become a real competitive alternative in the future. In general, superconductor design is the most competitive out of Direct Drive Systems and best fulfils the needs of the upcoming market - especially in the offshore market, where WECs with higher nominal power up to 10MW are required. Low weight, high reliability and the very good grid behaviour are the main advantages of the superconductor generator design and will lead to lower costs. The other systems are restricted to a smaller energy output range and / or onshore wind power production business.

  8. 5MW Direct Drive Wind Turbine Generator Design

    DEFF Research Database (Denmark)

    Zaidi, Arsalan; Senn, Lucile; Ortega, Iratxe

    2012-01-01

    A 5MW direct drive offshore wind turbine generator was studied and simulated using Vector Fields OPERA. This software allows calculation of the flux density, force, torque, and eddy currents in the machine at different rotor positions. Based on the data obtained from the model, initial assumptions...... for the suitable machine are listed and the modelling process presented. The model of the generator was improved by changing design parameters, e.g the position of the magnets or fitting additional I-Cores, and analyse the effect of it....

  9. Improvement of an installation to generate shock waves

    Energy Technology Data Exchange (ETDEWEB)

    1974-04-29

    An installation to generate a shock wave in a fluid layer is described. A water projectile is moved at a high velocity. It leaves behind an underpressure in which the adjacent water implodes, therby generating the desired shock wave. The installation is characterized by a tube-shaped hull in which a piston can move freely. One side of the hull is connected to the pressure-generator chamber of the piston. (6 claims)

  10. Fuzzy generation scheduling for a generation company (GenCo) with large scale wind farms

    International Nuclear Information System (INIS)

    Siahkali, H.; Vakilian, M.

    2010-01-01

    Wind power is a promising alternative in power generation because of its tremendous environmental and social benefits. Generation scheduling (GS) is more important in a power system integrating wind farms. Unlike conventional power generation sources, wind power generators supply intermittent power because of uncertainty in resource. This paper presents a fuzzy approach to the generation scheduling problem of a GenCo considering uncertainties in parameters or constraints such as load, reserve and available wind power generation. The modeling of constraints is an important issue in power system scheduling. A fuzzy optimization approach is an approach that can be used to obtain the generation scheduling under an uncertain environment. In this paper, a fuzzy optimization-based method is developed to solve power system GS problem with fuzzy objective and constraints. The crisp formulation of this GS problem is firstly defined and is rearranged by introduction of a membership function of some constraints and objective function. Then, this fuzzy optimization problem is converted to a crisp optimization and solved using GAMS software by mixed integer nonlinear programming. Employing the fuzzy optimization GS, it is expected that in practice a higher profit would be achieved in the operation and cost management of a real power system with large scale wind farms in different level of constraints' satisfaction. The proposed approach is applied to a sample system (including six conventional units and two wind farms) and the results are compared with the results of crisp solution. This approach is also applied to a larger test case to demonstrate the robustness of this fuzzy optimization method.

  11. Lightweight MgB2 superconducting 10 MW wind generator

    International Nuclear Information System (INIS)

    Marino, I; Pujana, A; Sarmiento, G; Sanz, S; Merino, J M; Tropeano, M; Sun, J; Canosa, T

    2016-01-01

    The offshore wind market demands a higher power rate and more reliable turbines in order to optimize capital and operational costs. The state-of-the-art shows that both geared and direct-drive conventional generators are difficult to scale up to 10 MW and beyond due to their huge size and weight. Superconducting direct-drive wind generators are considered a promising solution to achieve lighter weight machines. This work presents an innovative 10 MW 8.1 rpm direct-drive partial superconducting generator using MgB 2 wire for the field coils. It has a warm iron rotor configuration with the superconducting coils working at 20 K while the rotor core and the armature are at ambient temperature. A cooling system based on cryocoolers installed in the rotor extracts the heat from the superconducting coils by conduction. The generator’s main parameters are compared against a permanent magnet reference machine, showing a significant weight and size reduction. The 10 MW superconducting generator concept will be experimentally validated with a small-scale magnetic machine, which has innovative components such as superconducting coils, modular cryostats and cooling systems, and will have similar size and characteristics as the 10 MW generator. (paper)

  12. Ripple Field AC Losses in 10-MW Wind Turbine Generators With a MgB2 Superconducting Field Winding

    DEFF Research Database (Denmark)

    Liu, Dong; Polinder, Henk; Magnusson, Niklas

    2016-01-01

    Superconducting (SC) synchronous generators are proposed as a promising candidate for 10-20-MW direct-drive wind turbines because they can have low weights and small sizes. A common way of designing an SC machine is to use SC wires with high current-carrying capability in the dc field winding...... and the ac armature winding is made with copper conductors. In such generators, the dc field winding is exposed to ac magnetic field ripples due to space harmonics from the armature. In generator design phases, the ac loss caused by these ripple fields needs to be evaluated to avoid local overheating...... and an excessive cooling budget. To determine the applicability of different design solutions in terms of ac losses, this paper estimates the ac loss level of 10-MW wind generator designs employing a MgB2 SC field winding. The effects on ac losses are compared between nonmagnetic and ferromagnetic teeth...

  13. Influence of the characteristic and installation site of wind generator on quantity of produced energy

    International Nuclear Information System (INIS)

    Palge, V.; Lepa, J.; Tamm, T.

    2002-01-01

    In Estonia, especially in inland the wind speed is rather low. According to the Master thesis of Tonis Tamm the opportunities of use of several types of wind generators are analysed. It is found out, that the wind generator, beginning to produce energy at wind speed 2 m/s can in such conditions produce about four times more electricity energy than such having 'cut-in' wind speed 4 m/s. (author)

  14. Models for Numerical Evaluation of Variable Speed Different Wind Generator Systems

    DEFF Research Database (Denmark)

    Li, Hui; Chen, Zhe; Polinder, H.

    2007-01-01

    of different wind generator systems, the other presents the optimization results and evaluation of variable speed wind generator systems. In this report, firstly, it gives an overview of various wind generator topologies, including their advantages and disadvantages, market status and developing trends. Next...

  15. Terahertz wave generation in coupled quantum dots

    International Nuclear Information System (INIS)

    Ma Yu-Rong; Guo Shi-Fang; Duan Su-Qing

    2012-01-01

    Based on coupled quantum dots, we present an interesting optical effect in a four-level loop coupled system. Both the two upper levels and the two lower levels are designed to be almost degenerate, which induces a considerable dipole moment. The terahertz wave is obtained from the low-frequency component of the photon emission spectrum. The frequency of the terahertz wave can be controlled by tuning the energy levels via designing the nanostructure appropriately or tuning the driving laser field. A terahertz wave with adjustable frequency and considerable intensity (100 times higher than that of the Rayleigh line) can be obtained. It provides an effective scheme for a terahertz source. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  16. Statistical study of waves distribution in the inner magnetosphere using geomagnetic indices and solar wind parameters

    Science.gov (United States)

    Aryan, H.; Yearby, K.; Balikhin, M. A.; Krasnoselskikh, V.; Agapitov, O. V.

    2013-12-01

    The interaction of gyroresonant wave particles with chorus waves largely determine the dynamics of the Earth's radiation belts that effects the acceleration and loss of radiation belt electrons. The common approach is to present model waves distribution in the inner magnetosphere under different values of geomagnetic activity as expressed by the geomagnetic indices. However it is known that solar wind parameters such as bulk velocity (V) and density (n) are more effective in the control of high energy fluxes at the geostationary orbit. Therefore in the present study the set of parameters of the wave distribution is expanded to include the solar wind parameters in addition to the geomagnetic indices. The present study examines almost four years (01, January, 2004 to 29, September, 2007) of Cluster STAFF-SA, Double Star TC1 and OMNI data in order to present a combined model of wave magnetic field intensities for the chorus waves as a function of magnetic local time (MLT), L-shell (L*), geomagnetic activity, and solar wind velocity and density. Generally, the largest wave intensities are observed during average solar wind velocities (3006cm-3. On the other hand the wave intensity is lower and limited between 06:00 to 18:00 MLT for V700kms-1.

  17. Interaction of suprathermal solar wind electron fluxes with sheared whistler waves: fan instability

    Directory of Open Access Journals (Sweden)

    C. Krafft

    Full Text Available Several in situ measurements performed in the solar wind evidenced that solar type III radio bursts were some-times associated with locally excited Langmuir waves, high-energy electron fluxes and low-frequency electrostatic and electromagnetic waves; moreover, in some cases, the simultaneous identification of energetic electron fluxes, Langmuir and whistler waves was performed. This paper shows how whistlers can be excited in the disturbed solar wind through the so-called "fan instability" by interacting with energetic electrons at the anomalous Doppler resonance. This instability process, which is driven by the anisotropy in the energetic electron velocity distribution along the ambient magnetic field, does not require any positive slope in the suprathermal electron tail and thus can account for physical situations where plateaued reduced electron velocity distributions were observed in solar wind plasmas in association with Langmuir and whistler waves. Owing to linear calculations of growth rates, we show that for disturbed solar wind conditions (that is, when suprathermal particle fluxes propagate along the ambient magnetic field, the fan instability can excite VLF waves (whistlers and lower hybrid waves with characteristics close to those observed in space experiments.

    Key words. Space plasma physics (waves and instabilities – Radio Science (waves in plasma – Solar physics, astrophysics and astronomy (radio emissions

  18. Interaction of suprathermal solar wind electron fluxes with sheared whistler waves: fan instability

    Directory of Open Access Journals (Sweden)

    C. Krafft

    2003-07-01

    Full Text Available Several in situ measurements performed in the solar wind evidenced that solar type III radio bursts were some-times associated with locally excited Langmuir waves, high-energy electron fluxes and low-frequency electrostatic and electromagnetic waves; moreover, in some cases, the simultaneous identification of energetic electron fluxes, Langmuir and whistler waves was performed. This paper shows how whistlers can be excited in the disturbed solar wind through the so-called "fan instability" by interacting with energetic electrons at the anomalous Doppler resonance. This instability process, which is driven by the anisotropy in the energetic electron velocity distribution along the ambient magnetic field, does not require any positive slope in the suprathermal electron tail and thus can account for physical situations where plateaued reduced electron velocity distributions were observed in solar wind plasmas in association with Langmuir and whistler waves. Owing to linear calculations of growth rates, we show that for disturbed solar wind conditions (that is, when suprathermal particle fluxes propagate along the ambient magnetic field, the fan instability can excite VLF waves (whistlers and lower hybrid waves with characteristics close to those observed in space experiments.Key words. Space plasma physics (waves and instabilities – Radio Science (waves in plasma – Solar physics, astrophysics and astronomy (radio emissions

  19. Wave Disturbance Reduction of a Floating Wind Turbine Using a Reference Model-based Predictive Control

    DEFF Research Database (Denmark)

    Christiansen, Søren; Tabatabaeipour, Seyed Mojtaba; Bak, Thomas

    2013-01-01

    pitch such that the state trajectories of the controlled system tracks the reference trajectories. The framework is demonstrated with a reference model of the desired closed-loop system undisturbed by the incident waves. This allows the wave-induced motion of the platform to be damped significantly...... compared to a baseline floating wind turbine controller at the cost of more pitch action....

  20. Wing/kite-based wind energy generation: An overview

    Science.gov (United States)

    Milanese, M.

    2013-06-01

    Several technologies, aimed at converting high-altitude wind into electricity, are actually being investigated by companies, research centers and universities worldwide, and the community of people working in this field has coined the term airborne wind energy (AWE) as a common umbrella for these concepts. Indeed, many basic ideas that are now being developed in the context of AWE were already present in patents and publications since the '70s. Then, these ideas remained somehow silent, until more recent years, when several research groups and companies started to carry out theoretical, numerical and experimental analyses, made possible by important advances in diverse fields like materials, aerodynamics, sensors, computation and control. In this lecture, the basic AWE concepts and results that have been up to date accomplished are overviewed, with a focus on a particular class of AWE generators, namely with flexible wings and ground level generators, and emphasis on optimization and control aspects. Finally, we delineate what challenges are still to be faced, in order to fully demonstrate the viability of airborne wind energy.