WorldWideScience

Sample records for monitor wind speed

  1. Wind_Speeds_Master

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set included wind speeds for each subregion in the study (Georges Bank, Gulf of Maine, Southern New England, Middle Atlantic Bight) . The data came from...

  2. Wind speed perception and risk.

    Directory of Open Access Journals (Sweden)

    Duzgun Agdas

    Full Text Available BACKGROUND: How accurately do people perceive extreme wind speeds and how does that perception affect the perceived risk? Prior research on human-wind interaction has focused on comfort levels in urban settings or knock-down thresholds. No systematic experimental research has attempted to assess people's ability to estimate extreme wind speeds and perceptions of their associated risks. METHOD: We exposed 76 people to 10, 20, 30, 40, 50, and 60 mph (4.5, 8.9, 13.4, 17.9, 22.3, and 26.8 m/s winds in randomized orders and asked them to estimate wind speed and the corresponding risk they felt. RESULTS: Multilevel modeling showed that people were accurate at lower wind speeds but overestimated wind speeds at higher levels. Wind speed perceptions mediated the direct relationship between actual wind speeds and perceptions of risk (i.e., the greater the perceived wind speed, the greater the perceived risk. The number of tropical cyclones people had experienced moderated the strength of the actual-perceived wind speed relationship; consequently, mediation was stronger for people who had experienced fewer storms. CONCLUSION: These findings provide a clearer understanding of wind and risk perception, which can aid development of public policy solutions toward communicating the severity and risks associated with natural disasters.

  3. Wind Speed Perception and Risk

    Science.gov (United States)

    Agdas, Duzgun; Webster, Gregory D.; Masters, Forrest J.

    2012-01-01

    Background How accurately do people perceive extreme wind speeds and how does that perception affect the perceived risk? Prior research on human–wind interaction has focused on comfort levels in urban settings or knock-down thresholds. No systematic experimental research has attempted to assess people's ability to estimate extreme wind speeds and perceptions of their associated risks. Method We exposed 76 people to 10, 20, 30, 40, 50, and 60 mph (4.5, 8.9, 13.4, 17.9, 22.3, and 26.8 m/s) winds in randomized orders and asked them to estimate wind speed and the corresponding risk they felt. Results Multilevel modeling showed that people were accurate at lower wind speeds but overestimated wind speeds at higher levels. Wind speed perceptions mediated the direct relationship between actual wind speeds and perceptions of risk (i.e., the greater the perceived wind speed, the greater the perceived risk). The number of tropical cyclones people had experienced moderated the strength of the actual–perceived wind speed relationship; consequently, mediation was stronger for people who had experienced fewer storms. Conclusion These findings provide a clearer understanding of wind and risk perception, which can aid development of public policy solutions toward communicating the severity and risks associated with natural disasters. PMID:23226230

  4. Forecasting Solar Wind Speeds

    CERN Document Server

    Suzuki, T K

    2006-01-01

    By explicitly taking into account effects of Alfven waves, I derive from a simple energetics argument a fundamental relation which predicts solar wind (SW) speeds in the vicinity of the earth from physical properties on the sun. Kojima et al. recently found from their observations that a ratio of surface magnetic field strength to an expansion factor of open magnetic flux tubes is a good indicator of the SW speed. I show by using the derived relation that this nice correlation is an evidence of the Alfven wave which accelerates SW in expanding flux tubes. The observations further require that fluctuation amplitudes of magnetic field lines at the surface should be almost universal in different coronal holes, which needs to be tested by future observations.

  5. NTF – wind speed comparison

    DEFF Research Database (Denmark)

    Vesth, Allan; Gómez Arranz, Paula

    The report describes measurements carried out on a given turbine. A comparison between wind speed on the met mast and Nacelle Wind speed are made and the results are presented on graphs and in a table. The data used for the comparison are the data that are same as used for the power curve report...

  6. Oceanic Wind Speed and Wind Stress Estimation from Ambient Noise Measurements.

    Science.gov (United States)

    1977-02-01

    it was found that noise records may be used to monitor wind speed and wind stress over the ocean. Time series of wind speeds can be produced from...wind direction, the wind stress has also been estimated and vector-averaged. The monthly mean stress from the authors’ data is higher than values

  7. Wind speed forecasting for wind energy applications

    Science.gov (United States)

    Liu, Hong

    With more wind energy being integrated into our grid systems, forecasting wind energy has become a necessity for all market participants. Recognizing the market demands, a physical approach to site-specific hub-height wind speed forecasting system has been developed. This system is driven by the outputs from the Canadian Global Environmental Multiscale (GEM) model. A simple interpolation approach benchmarks the forecasting accuracy inherited from GEM. Local, site specific winds are affected on a local scale by a variety of factors including representation of the land surface and local boundary-layer process over heterogeneous terrain which have been a continuing challenge in NWP models like GEM with typical horizontal resolution of order 15-km. In order to resolve these small scale effects, a wind energy industry standard model, WAsP, is coupled with GEM to improve the forecast. Coupling the WAsP model with GEM improves the overall forecasts, but remains unsatisfactory for forecasting winds with abrupt surface condition changes. Subsequently in this study, a new coupler that uses a 2-D RANS model of boundary-layer flow over surface condition changes with improved physics has been developed to further improve the forecasts when winds coming from a water surface to land experience abrupt changes in surface conditions. It has been demonstrated that using vertically averaged wind speeds to represent geostrophic winds for input into the micro-scale models could reduce forecast errors. The hub-height wind speed forecasts could be further improved using a linear MOS approach. The forecasting system has been evaluated, using a wind energy standard evaluation matrix, against data from an 80-m mast located near the north shore of Lake Erie. Coupling with GEM-LAM and a power conversion model using a theoretical power curve have also been investigated. For hub-height wind speeds GEM appears to perform better with a 15-Ian grid than the high resolution GEM-2.5Ian version at the

  8. Condition Monitoring with WinTControl {sup trademark} in variable-speed wind power systems; Condition Monitoring mit WinTControl {sup trademark} an drehzahlveraenderlichen Windenergieanlagen

    Energy Technology Data Exchange (ETDEWEB)

    Becker; Dahlhaus, N. [Flender Service GmbH, Herne (Germany). Abt. Condition Monitoring

    2003-07-01

    In 2002, German insurance company had to pay the all-time high of about 40 million Euro for damage in wind power systems. In consequence, a servicing and maintenance clause is now included in the insurance contracts, and requirements on condition monitoring for wind power systems were defined. Condition monitoring is based on an analysis of vibrations of components that are subject to wear, i.e. gears, generators, toothing, roller bearings, rotors, and electric components. All of these have typical and significant vibration patterns which can be measured and compared in order to assess the status of a plant by high-sensitivity spectral analyses. The contribution presents the examples of reversible, constant-speed asynchronous generators with gears and of double-fed, variable-speed asynchronous generators with gears. (orig.) [German] Im Jahre 2002 haben die deutschen Versicherer fuer Schaeden an Windenergieanlagen (WEA) den Spitzenwert von rund 40 Mio. Euro bezahlt, was unter anderem dazu fuehrte, dass eine Wartungs- und Instandhaltungsklausel in die Vertraege aufgenommen und Anforderungen an ein geeignetes Condition Monitoring fuer Windenergieanlagen definiert wurden. Basis des Condition Monitoring sind 'Soll/Ist-Vergleiche' des Schwingungsverhaltens verschleissbehafteter Komponenten. Getriebe, Generatoren, Verzahnungen, Waelzlager, Rotoren und E-Technikkomponenten haben typische und signifikante Schwingungsbilder, welche bei Messung unter vergleichbaren Betriebsbedingungen eine einfache Beurteilung der Zustandveraenderung erlauben. Zustandsveraenderungen dieser Komponenten lassen sich ueber Spektralanalysen hochempfindlich verfolgen. Wie sich das Condition Monitoring an WEA dennoch realisieren laesst, wird nachfolgend an Triebstraengen mit polumschaltbaren, drehzahlstarren Asynchrongeneratoren mit Getrieben und an doppeltgespeisten, drehzahlveraenderlichen Asynchrongeneratoren mit Getrieben beschrieben. (orig.)

  9. Towards an automatic system for monitoring of CN2 and wind speed profiles with GeMS

    CERN Document Server

    Masciadri, E; Guesalaga, A; Turchi, A

    2016-01-01

    Wide Field Adaptive Optics (WFAO) systems represent the more sophisticated AO systems available today at large telescopes. A critical aspect for these WFAO systems in order to deliver an optimised performance is the knowledge of the vertical spatiotemporal distribution of the CN2 and the wind speed. Previous studies (Cortes et al., 2012) already proved the ability of GeMS (the Gemini Multi-Conjugated AO system) in retrieving CN2 and wind vertical stratification using the telemetry data. To assess the reliability of the GeMS wind speed estimates a preliminary study (Neichel et al., 2014) compared wind speed retrieved from GeMS with that obtained with the atmospherical model Meso-Nh on a small sample of nights providing promising results. The latter technique is very reliable for the wind speed vertical stratification. The model outputs gave, indeed, an excellent agreement with a large sample of radiosoundings (~ 50) both in statistical terms and on individual flights (Masciadri et al., 2013). Such a tool can t...

  10. Deterministic prediction of surface wind speed variations

    OpenAIRE

    Drisya, G. V.; Kiplangat, D. C.; Asokan, K; K. Satheesh Kumar

    2014-01-01

    Accurate prediction of wind speed is an important aspect of various tasks related to wind energy management such as wind turbine predictive control and wind power scheduling. The most typical characteristic of wind speed data is its persistent temporal variations. Most of the techniques reported in the literature for prediction of wind speed and power are based on statistical methods or probabilistic distribution of wind speed data. In this paper we demonstrate that determin...

  11. Unsafe at Any (Wind) Speed?.

    Science.gov (United States)

    Schmidlin, Thomas; Hammer, Barbara; King, Paul; Ono, Yuichi; Miller, L. Scott; Thumann, Gregory

    2002-12-01

    The goal of this research was to examine the relative safety and stability of stationary motor vehicles exposed to severe winds. The focus was on private passenger vehicles. 1) The behavior of two instrumented storm-chase vehicles that were exposed to severe winds, 2) the behavior of 291 vehicles exposed to a tornado, and 3) the wind speed required to upset a sedan and a minivan exposed to winds in a wind tunnel were studied. A wind as strong as 47 m s1 (105 mph) has been measured by a storm-chase pickup truck and 44 m s1 (98 mph) by a storm chase sedan. The vehicles were not adversely affected by the wind. Also studied were 291 vehicles parked outdoors at homes struck by tornadoes, and the behavior of the vehicles was compared to the F-scale damage to the house. At sites with F1 or F2 damage, 72% of the vehicles were not moved by the wind and 96% were not tipped over. At sites with F3 or F4 damage, 50% were not moved by the wind and 82% were not tipped over. Wind tunnel tests on a sedan and minivan showed they were most vulnerable to upset (lifting of one tire from the ground) with wind directions near 45° and 135°, as measured from the front. When modeled with 5° of suspension tilt to the side, the sedan was found to be upset at wind speeds of 51-67 m s1 (115-150 mph), and the minivan was upset at wind speeds of 58-80 m s1 (130-180 mph). Although an underground shelter or sturdy building offer the best protection from severe winds, it is found that a vehicle may be a relatively stable place and may be safer than a mobile home or the outdoors. These findings may warrant changes to public recommendations made during tornado warnings and other severe storm situations.

  12. Hanford Site peak gust wind speeds

    Energy Technology Data Exchange (ETDEWEB)

    Ramsdell, J.V.

    1998-09-29

    Peak gust wind data collected at the Hanford Site since 1945 are analyzed to estimate maximum wind speeds for use in structural design. The results are compared with design wind speeds proposed for the Hanford Site. These comparisons indicate that design wind speeds contained in a January 1998 advisory changing DOE-STD-1020-94 are excessive for the Hanford Site and that the design wind speeds in effect prior to the changes are still appropriate for the Hanford Site.

  13. Speed control at low wind speeds for a variable speed fixed pitch wind turbine

    Energy Technology Data Exchange (ETDEWEB)

    Rosmin, N.; Watson, S.J.; Tompson, M. [Loughborough Univ., Loughborough, Leicestershire (United Kingdom)

    2010-03-09

    The maximum power regulation below rated wind speed is regulated by changing the rotor/generator speed at large frequency range in a fixed pitch, variable speed, stall-regulated wind turbine. In order to capture the power at a maximum value the power coefficient is kept at maximum peak point by maintaining the tip speed ratio at its optimum value. The wind industry is moving from stall regulated fixed speed wind turbines to newer improved innovative versions with better reliability. While a stall regulated fixed pitch wind turbine is among the most cost-effective wind turbine on the market, its problems include noise, severe vibrations, high thrust loads and low power efficiency. Therefore, in order to improve such drawbacks, the rotation of the generator speed is made flexible where the rotation can be controlled in variable speed. This paper discussed the development of a simulation model which represented the behaviour of a stall regulated variable speed wind turbine at low wind speed control region by using the closed loop scalar control with adjustable speed drive. The paper provided a description of each sub-model in the wind turbine system and described the scalar control of the induction machine. It was concluded that by using a constant voltage/frequency ratio of the generator's stator side control, the generator speed could be regulated and the generator torque could be controlled to ensure the power coefficient could be maintained close to its maximum value. 38 refs., 1 tab., 10 figs.

  14. Fault tolerant wind speed estimator used in wind turbine controllers

    DEFF Research Database (Denmark)

    Odgaard, Peter Fogh; Stoustrup, Jakob

    2012-01-01

    . In this paper a fault tolerant wind speed estimator is designed based on a set of unknown input observers, each designed to the different sets of non-faulty sensors. Faults in the rotor, generator and wind speed sensors are considered. The designed wind speed estimator is passive tolerant towards faults...... in the wind speed sensors, and faults in the generator and rotor speed sensors are accommodated by an active fault tolerant observer scheme in which the faults are detected and identified, and the observer corresponding to the non-faulty sensors are used. The potential of the scheme is shown by applying......Advanced control schemes can be used to optimize energy production and cost of energy in modern wind turbines. These control schemes most often rely on wind speed estimations. These designs of wind speed estimators are, however, not designed to be fault tolerant towards faults in the used sensors...

  15. Wind speed assessment at Treculliacks, Constantine, Falmouth, Cornwall

    Energy Technology Data Exchange (ETDEWEB)

    Williams, G.J.; Angell, R.K.; Collis, J.A.; Odgers, M.; Beechey-Newman, H.J.A.; Shaw, G.A.

    1995-05-01

    An anemometer mast was erected at Treculliacks close to the proposed position for Windpower`s next wind turbine. Anemometers were mounted at 15 and 25 m agl. Wind velocity was monitored from June 1991 to February 1992 inclusive and referenced to the long term record at St. Mawgan. The predicted long term mean annual wind speed was compared with the measured results. The net annual wind turbine output is predicted. (UK)

  16. When real life wind speed exceeds design wind assumptions

    Energy Technology Data Exchange (ETDEWEB)

    Winther-Jensen, M.; Joergensen, E.R. [Risoe National Lab., Roskilde (Denmark)

    1999-03-01

    Most modern wind turbines are designed according to a standard or a set of standards to withstand the design loads with a defined survival probability. Mainly the loads are given by the wind conditions on the site defining the `design wind speeds`, normally including extreme wind speeds given as an average and a peak value. The extreme wind speeds are normally (e.g. in the upcoming IEC standard for wind turbine safety) defined as having a 50-year recurrence period. But what happens when the 100 or 10,000 year wind situation hits a wind turbine? Results on wind turbines of wind speeds higher than the extreme design wind speeds are presented based on experiences especially from the State of Gujarat in India. A description of the normal approach of designing wind turbines in accordance with the standards in briefly given in this paper with special focus on limitations and built-in safety levels. Based on that, other possibilities than just accepting damages on wind turbines exposed for higher than design wind speeds are mentioned and discussed. The presentation does not intend to give the final answer to this problem but is meant as an input to further investigations and discussions. (au)

  17. Mars - Wind friction speeds for particle movement

    Science.gov (United States)

    Greeley, R.; Leach, R.; White, B.; Iversen, J.; Pollack, J.

    1976-01-01

    Wind friction threshold speeds for particle movement were determined in a low pressure boundary layer wind tunnel at an atmospheric pressure of 5.3 mb. The results imply that for comparable pressures on Mars, the minimum wind friction threshold speed is about 2.5 m/sec, which would require free-stream winds of 50 to 135 m/sec, depending on the character of the surface and the atmospheric conditions. The corresponding wind speeds at the height of the Viking lander meteorology instrument would be about a factor of two less than the free-stream wind speed. The particle size most easily moved by winds on Mars is about 160 microns; particles both larger and smaller than this (at least down to about 5 microns) require stronger winds to initiate movement.

  18. Feed forward control of estimated wind speed

    Energy Technology Data Exchange (ETDEWEB)

    Van Engelen, T.G.; Van der Hooft, E.L. [ECN Wind Energy, Petten (Netherlands)

    2003-12-01

    A control structure 'feed forward of estimated wind speed' is described, as it were: 'the wind turbine rotor will be used as a wind meter'. The control structure is based on 'estimation' of wind speed as well as a non-linear compensation of a wind speed dependent pitch speed setpoint, which is optimised to maintain (stationary) rated electric power. It is required to know the rotor properties with moderate accuracy. In time domain simulations, inclusion of a feed forward of estimated wind speed control action has shown to be a powerful extension to current ECN wind turbine control structures: reduction of rotor speed variations: 0.2 rpm decreased standard deviation; improved turbine behaviour to large wind gusts; increase of energy yield of 0.9%; For reasons of simplicity and robustness, a tabular implementation approach is preferred above polynomial implementation. The resulting brief algorithm uses small sized tables, requires low hardware requirements and needs a minimum of easy interpretable parameters for design and tuning. Both stability, robustness and parametric uncertainties were observed. The addition control loop has a slightly positive effect on overall stability and robustness. Appeared offsets in the estimated wind speed value due to parameter uncertainties do not have impact on the effectuation of the wind speed feed forward loop.

  19. Deterministic prediction of surface wind speed variations

    Science.gov (United States)

    Drisya, G. V.; Kiplangat, D. C.; Asokan, K.; Satheesh Kumar, K.

    2014-11-01

    Accurate prediction of wind speed is an important aspect of various tasks related to wind energy management such as wind turbine predictive control and wind power scheduling. The most typical characteristic of wind speed data is its persistent temporal variations. Most of the techniques reported in the literature for prediction of wind speed and power are based on statistical methods or probabilistic distribution of wind speed data. In this paper we demonstrate that deterministic forecasting methods can make accurate short-term predictions of wind speed using past data, at locations where the wind dynamics exhibit chaotic behaviour. The predictions are remarkably accurate up to 1 h with a normalised RMSE (root mean square error) of less than 0.02 and reasonably accurate up to 3 h with an error of less than 0.06. Repeated application of these methods at 234 different geographical locations for predicting wind speeds at 30-day intervals for 3 years reveals that the accuracy of prediction is more or less the same across all locations and time periods. Comparison of the results with f-ARIMA model predictions shows that the deterministic models with suitable parameters are capable of returning improved prediction accuracy and capturing the dynamical variations of the actual time series more faithfully. These methods are simple and computationally efficient and require only records of past data for making short-term wind speed forecasts within practically tolerable margin of errors.

  20. Wind turbine control and monitoring

    CERN Document Server

    Luo, Ningsu; Acho, Leonardo

    2014-01-01

    Maximizing reader insights into the latest technical developments and trends involving wind turbine control and monitoring, fault diagnosis, and wind power systems, 'Wind Turbine Control and Monitoring' presents an accessible and straightforward introduction to wind turbines, but also includes an in-depth analysis incorporating illustrations, tables and examples on how to use wind turbine modeling and simulation software.   Featuring analysis from leading experts and researchers in the field, the book provides new understanding, methodologies and algorithms of control and monitoring, comput

  1. Fiber Laser for Wind Speed Measurements

    DEFF Research Database (Denmark)

    Olesen, Anders Sig

    This PhD thesis evaluates the practical construction and use of a Frequency Stepped Pulse Train modulated coherent Doppler wind lidar (FSPT lidar) for wind speed measurement. The concept of Doppler lidar is introduced as a means to measure line of sight wind speed by the Doppler shift of reflected...... of concept wind speed measurements obtained with the FSPT lidar are shown. This is followed by a discussion of the advantages and disadvantages of a FSPT lidar compared to a CW and a pulsed lidar system, and further avenues for evolving the concepts....

  2. WIND SPEED AND ENERGY POTENTIAL ANALYSES

    Directory of Open Access Journals (Sweden)

    A. TOKGÖZLÜ

    2013-01-01

    Full Text Available This paper provides a case study on application of wavelet techniques to analyze wind speed and energy (renewable and environmental friendly energy. Solar and wind are main sources of energy that allows farmers to have the potential for transferring kinetic energy captured by the wind mill for pumping water, drying crops, heating systems of green houses, rural electrification's or cooking. Larger wind turbines (over 1 MW can pump enough water for small-scale irrigation. This study tried to initiate data gathering process for wavelet analyses, different scale effects and their role on wind speed and direction variations. The wind data gathering system is mounted at latitudes: 37° 50" N; longitude 30° 33" E and height: 1200 m above mean sea level at a hill near Süleyman Demirel University campus. 10 minutes average values of two levels wind speed and direction (10m and 30m above ground level have been recorded by a data logger between July 2001 and February 2002. Wind speed values changed between the range of 0 m/s and 54 m/s. Annual mean speed value is 4.5 m/s at 10 m ground level. Prevalent wind

  3. LIDAR Wind Speed Measurements of Evolving Wind Fields

    Energy Technology Data Exchange (ETDEWEB)

    Simley, E.; Pao, L. Y.

    2012-07-01

    Light Detection and Ranging (LIDAR) systems are able to measure the speed of incoming wind before it interacts with a wind turbine rotor. These preview wind measurements can be used in feedforward control systems designed to reduce turbine loads. However, the degree to which such preview-based control techniques can reduce loads by reacting to turbulence depends on how accurately the incoming wind field can be measured. Past studies have assumed Taylor's frozen turbulence hypothesis, which implies that turbulence remains unchanged as it advects downwind at the mean wind speed. With Taylor's hypothesis applied, the only source of wind speed measurement error is distortion caused by the LIDAR. This study introduces wind evolution, characterized by the longitudinal coherence of the wind, to LIDAR measurement simulations to create a more realistic measurement model. A simple model of wind evolution is applied to a frozen wind field used in previous studies to investigate the effects of varying the intensity of wind evolution. LIDAR measurements are also evaluated with a large eddy simulation of a stable boundary layer provided by the National Center for Atmospheric Research. Simulation results show the combined effects of LIDAR errors and wind evolution for realistic turbine-mounted LIDAR measurement scenarios.

  4. A New Fault Diagnosis Algorithm for PMSG Wind Turbine Power Converters under Variable Wind Speed Conditions

    Directory of Open Access Journals (Sweden)

    Yingning Qiu

    2016-07-01

    Full Text Available Although Permanent Magnet Synchronous Generator (PMSG wind turbines (WTs mitigate gearbox impacts, they requires high reliability of generators and converters. Statistical analysis shows that the failure rate of direct-drive PMSG wind turbines’ generators and inverters are high. Intelligent fault diagnosis algorithms to detect inverters faults is a premise for the condition monitoring system aimed at improving wind turbines’ reliability and availability. The influences of random wind speed and diversified control strategies lead to challenges for developing intelligent fault diagnosis algorithms for converters. This paper studies open-circuit fault features of wind turbine converters in variable wind speed situations through systematic simulation and experiment. A new fault diagnosis algorithm named Wind Speed Based Normalized Current Trajectory is proposed and used to accurately detect and locate faulted IGBT in the circuit arms. It is compared to direct current monitoring and current vector trajectory pattern approaches. The results show that the proposed method has advantages in the accuracy of fault diagnosis and has superior anti-noise capability in variable wind speed situations. The impact of the control strategy is also identified. Experimental results demonstrate its applicability on practical WT condition monitoring system which is used to improve wind turbine reliability and reduce their maintenance cost.

  5. Low wind speed wind turbine in DIY version

    OpenAIRE

    Van den Bossche, Alex

    2013-01-01

    Wind energy has still a place, as it can generate power in the winter, when less sun is available and when the wind speed is higher. This paper proposes a solution for low cost blades from a polyethylene pipe (PE) and a low cost electric bike generator, which is possible to realize by a do it yourself (DIY) person. It is intended as low wind speed wind turbine (LWWT). The design is rather optimized towards a low cost/swept area, rather than the cost/nominal power. It uses a variant on the fur...

  6. Low Speed Wind Tunnel Facility (LSWTF)

    Data.gov (United States)

    Federal Laboratory Consortium — Description: This facility consists of a large-scale, low-speed open-loop induction wind tunnel which has been modified to house a linear turbine cascade. A 125-hp...

  7. Modelling Wind for Wind Farm Layout Optimization Using Joint Distribution of Wind Speed and Wind Direction

    Directory of Open Access Journals (Sweden)

    Ju Feng

    2015-04-01

    Full Text Available Reliable wind modelling is of crucial importance for wind farm development. The common practice of using sector-wise Weibull distributions has been found inappropriate for wind farm layout optimization. In this study, we propose a simple and easily implementable method to construct joint distributions of wind speed and wind direction, which is based on the parameters of sector-wise Weibull distributions and interpolations between direction sectors. It is applied to the wind measurement data at Horns Rev and three different joint distributions are obtained, which all fit the measurement data quite well in terms of the coefficient of determination . Then, the best of these joint distributions is used in the layout optimization of the Horns Rev 1 wind farm and the choice of bin sizes for wind speed and wind direction is also investigated. It is found that the choice of bin size for wind direction is especially critical for layout optimization and the recommended choice of bin sizes for wind speed and wind direction is finally presented.

  8. Wind speed vertical distribution at Mt. Graham

    CERN Document Server

    Hagelin, S; Lascaux, F

    2010-01-01

    The characterization of the wind speed vertical distribution V(h) is fundamental for an astronomical site for many different reasons: (1) the wind speed shear contributes to trigger optical turbulence in the whole troposphere, (2) a few of the astroclimatic parameters such as the wavefront coherence time (tau_0) depends directly on V(h), (3) the equivalent velocity V_0, controlling the frequency at which the adaptive optics systems have to run to work properly, depends on the vertical distribution of the wind speed and optical turbulence. Also, a too strong wind speed near the ground can introduce vibrations in the telescope structures. The wind speed at a precise pressure (200 hPa) has frequently been used to retrieve indications concerning the tau_0 and the frequency limits imposed to all instrumentation based on adaptive optics systems, but more recently it has been proved that V_200 (wind speed at 200 hPa) alone is not sufficient to provide exhaustive elements concerning this topic and that the vertical d...

  9. Ocean Surface Wind Speed of Hurricane Helene Observed by SAR

    DEFF Research Database (Denmark)

    Xu, Qing; Cheng, Yongcun; Li, Xiaofeng

    2011-01-01

    The hurricanes can be detected by many remote sensors, but synthetic aperture radar (SAR) can yield high-resolution (sub-kilometer) and low-level wind information that cannot be seen below the cloud by other sensors. In this paper, an assessment of SAR capability of monitoring high-resolution hur......The hurricanes can be detected by many remote sensors, but synthetic aperture radar (SAR) can yield high-resolution (sub-kilometer) and low-level wind information that cannot be seen below the cloud by other sensors. In this paper, an assessment of SAR capability of monitoring high......-resolution hurricane was conducted. A case study was carried out to retrieve ocean surface wind field from C-band RADARSAT-1 SAR image which captured the structure of hurricane Helene over the Atlantic Ocean on 20 September, 2006. With wind direction from the outputs of U.S. Navy Operational Global Atmospheric...... CIWRAP models have been tested to extract wind speed from SAR data. The SAR retrieved ocean surface winds were compared to the aircraft wind speed observations from stepped frequency microwave radiometer (SFMR). The results show the capability of hurricane wind monitoring by SAR....

  10. Effect of Wind Direction on ENVISAT ASAR Wind Speed Retrieval

    DEFF Research Database (Denmark)

    Takeyama, Yuko; Ohsawa, Teruo; Kozai, Katsutoshi

    2010-01-01

    This paper presents an evaluation of effects of wind directions (NCEP, MANAL, QuickSCAT and WRF) on the sea surface wind speed retrieval from 75 ENVISAT ASAR images with four C-band Geophysical model functions, CMOD4, CMOD_IFR2, CMOD5 and CMOD5N at two target areas, Hiratsuka and Shirahama...

  11. Virtual inertia for variable speed wind turbines

    DEFF Research Database (Denmark)

    Zeni, Lorenzo; Rudolph, Andreas Jakob; Münster-Swendsen, Janus

    2013-01-01

    Inertia provision for frequency control is among the ancillary services that different national grid codes will likely require to be provided by future wind turbines. The aim of this paper is analysing how the inertia response support from a variable speed wind turbine (VSWT) to the primary...... frequency control of a power system can be enhanced. Unlike fixed speed wind turbines, VSWTs do not inherently contribute to system inertia, as they are decoupled from the power system through electronic converters. Emphasis in this paper is on how to emulate VSWTs inertia using control of the power...

  12. Development of Low Wind Speed Anemometer

    Directory of Open Access Journals (Sweden)

    Tan Wee Choon

    2012-01-01

    Full Text Available Anemometer is a measuring device used to measure the wind speed of an area. Before design or installing a wind turbine, it is important to determine the average wind speed of that particular area throughout the year. But it is illogically to purchase anemometer to measure the wind velocity for a year period. The purpose of this project is to design and fabricate a small scale of anemometer which will able to give the wind velocity with an acceptable range of uncertainty. The fabrication of the anemometer is developed using design methodology and simulation to obtain the optimized design. The designed anemometer has the mean absolute percentage error (MAPE of 3.23 % when compared with Dwyer series 471 thermo-anemometer.

  13. Modelling Wind for Wind Farm Layout Optimization Using Joint Distribution of Wind Speed and Wind Direction

    DEFF Research Database (Denmark)

    Feng, Ju; Shen, Wen Zhong

    2015-01-01

    Reliable wind modelling is of crucial importance for wind farm development. The common practice of using sector-wise Weibull distributions has been found inappropriate for wind farm layout optimization. In this study, we propose a simple and easily implementable method to construct joint distribu......Reliable wind modelling is of crucial importance for wind farm development. The common practice of using sector-wise Weibull distributions has been found inappropriate for wind farm layout optimization. In this study, we propose a simple and easily implementable method to construct joint...... quite well in terms of the coefficient of determination R-2. Then, the best of these joint distributions is used in the layout optimization of the Horns Rev 1 wind farm and the choice of bin sizes for wind speed and wind direction is also investigated. It is found that the choice of bin size for wind...... direction is especially critical for layout optimization and the recommended choice of bin sizes for wind speed and wind direction is finally presented....

  14. LIDAR wind speed measurements at a Taiwan onshore wind park

    Science.gov (United States)

    Wu, Yu-Ting; Lin, Ta-Hui; Hsuan, Chung-Yao; Li, Yu-Cheng; Yang, Ya-Fei; Tai, Tzy-Hwan; Huang, Chien-Cheng

    2016-04-01

    Measurements of wind speed and wind direction were carried out using a Leosphere Windcube LIDAR system at a Taiwan onshore wind park. The Lidar shot a total of five laser beams to the atmosphere to collect the light-of-sight (LOS) velocity. Four beams were sent successively in four cardinal directions along a 28° scanning cone angle, followed by a fifth, vertical beam. An unchangeable sampling rate of approximately 1.2 Hz was set in the LIDAR system to collect the LOS velocity. The supervisory control and data acquisition (SCADA) data from two GE 1.5 MW wind turbines near the LIDAR deployment site were acquired for the whole measuring period from February 4 to February 16 of 2015. The SCADA data include the blade angular velocity, the wind velocity measured at hub height from an anemometer mounted on the nacelle, the wind turbine yaw angle, and power production; each parameter was recorded as averages over 1-min periods. The data analysis involving the LIDAR measurements and the SCADA data were performed to obtain the turbulent flow statistics. The results show that the turbine power production has significant dependence to the wind speed, wind direction, turbulence intensity and wind shear.

  15. Locating air quality monitoring station using wind impact area diagram.

    Science.gov (United States)

    George, K V; Verma, P; Devotta, S

    2008-10-01

    In this study a new methodology is suggested to approximate the impact area downwind of an air pollution source, where air quality monitoring can be carried out to capture the maximum pollutant concentration. Hourly wind speed for a given month is grouped in to different wind speed ranges and the distance of pollutant travel is approximated from the average wind speed of that wind speed range. Since change in wind direction causes the impact distance to rotate, its rotation is approximated by the SD of wind direction change. Using this approach, area or region down wind of a source is determined and plotted. The pattern of monthly change of wind is better represented by the new type of diagram as compared to the wind rose diagram.

  16. 3D Wind: Quantifying wind speed and turbulence intensity

    Science.gov (United States)

    Barthelmie, R. J.; Pryor, S. C.; Wang, H.; Crippa, P.

    2013-12-01

    Integrating measurements and modeling of wind characteristics for wind resource assessment and wind farm control is increasingly challenging as the scales of wind farms increases. Even offshore or in relatively homogeneous landscapes, there are significant gradients of both wind speed and turbulence intensity on scales that typify large wind farms. Our project is, therefore, focused on (i) improving methods to integrate remote sensing and in situ measurements with model simulations to produce a 3-dimensional view of the flow field on wind farm scales and (ii) investigating important controls on the spatiotemporal variability of flow fields within the coastal zone. The instrument suite deployed during the field experiments includes; 3-D sonic and cup anemometers deployed on meteorological masts and buoys, anemometers deployed on tethersondes and an Unmanned Aerial Vehicle, multiple vertically-pointing continuous-wave lidars and scanning Doppler lidars. We also integrate data from satellite-borne instrumentation - specifically synthetic aperture radar and scatterometers and output from the Weather Research and Forecast (WRF) model. Spatial wind fields and vertical profiles of wind speed from WRF and from the full in situ observational suite exhibit excellent agreement in a proof-of-principle experiment conducted in north Indiana particularly during convective conditions, but showed some discrepancies during the breakdown of the nocturnal stable layer. Our second experiment in May 2013 focused on triangulating a volume above an area of coastal water extending from the port in Cleveland out to an offshore water intake crib (about 5 km) and back to the coast, and includes extremely high resolution WRF simulations designed to characterize the coastal zone. Vertically pointing continuous-wave lidars were operated at each apex of the triangle, while the scanning Doppler lidar scanned out across the water over 90 degrees azimuth angle. Preliminary results pertaining to

  17. Modeling wind adjustment factor and midflame wind speed for Rothermel's surface fire spread model

    Science.gov (United States)

    Patricia L. Andrews

    2012-01-01

    Rothermel's surface fire spread model was developed to use a value for the wind speed that affects surface fire, called midflame wind speed. Models have been developed to adjust 20-ft wind speed to midflame wind speed for sheltered and unsheltered surface fuel. In this report, Wind Adjustment Factor (WAF) model equations are given, and the BehavePlus fire modeling...

  18. Wind speed scaling and the drag coefficient

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Wind speed scaling in similarity law in wind-generated waves and the drag coefficient are studied. In analyzing the data in the wind wave channel, it is found that the u. scaling greatly reduces the scatter in the U10 scaling. The u. scaling has much less scatter than the scaling using other wind speeds. The friction velocity seems to play a distinctive role in wave growth. The result is important in the applications of the similarity law and in wave modeling. In theory it gives an insight into the mechanism of wind wave interaction. It is found that wave steepness is important in influencing the drag coefficient. The variability of the coefficients in the currently widely used drag form can be explained by the differences in wave steepness in the observations. A drag coefficient model with wind speed and wave steepness as parameters is proposed. An explanation for Kahma' s result that the u. scaling does not reduce the scatter in the U10 scaling is given.

  19. ACCUWIND - Accurate wind speed measurements in wind energy - Summary report

    DEFF Research Database (Denmark)

    Friis Pedersen, Troels; Dahlberg, J.-Å.; Cuerva, A.

    2006-01-01

    The cup anemometer is at present the standard instrument used for mean wind speed measurement in wind energy. It is being applied in high numbers around the world for wind energy assessments. It is also applied exclusively for accredited power performancemeasurements for certification...... and verification purposes, and for purposes of optimisation in research and development. The revised IEC standard on power performance measurements has now included requirements for classification of cup anemometers. Thebasis for setting up such requirements of cup anemometers is two EU projects SITEPARIDEN...... and CLASSCUP from which the proposed classification method for cup anemometers was developed for the IEC standard. While cup anemometers at present are the standardanemometer being used for average wind speed measurements, sonic anemometers have been developed significantly over the last years, and prices have...

  20. Estimation of Rotor Effective Wind Speed: A Comparison

    DEFF Research Database (Denmark)

    Soltani, Mohsen; Knudsen, Torben; Svenstrup, Mikael

    2013-01-01

    Modern wind turbine controllers use wind speed information to improve power production and reduce loads on the turbine components. The turbine top wind speed measurement is unfortunately imprecise and not a good representative of the rotor effective wind speed. Consequently, many different model...

  1. Wind Speed Measurement by Paper Anemometer

    Science.gov (United States)

    Zhong, Juhua; Cheng, Zhongqi; Guan, Wenchuan

    2011-01-01

    A simple wind speed measurement device, a paper anemometer, is fabricated based on the theory of standing waves. In providing the working profile of the paper anemometer, an experimental device is established, which consists of an anemometer sensor, a sound sensor, a microphone, paper strips, a paper cup, and sonic acquisition software. It shows…

  2. Wind Speed Measurement by Paper Anemometer

    Science.gov (United States)

    Zhong, Juhua; Cheng, Zhongqi; Guan, Wenchuan

    2011-01-01

    A simple wind speed measurement device, a paper anemometer, is fabricated based on the theory of standing waves. In providing the working profile of the paper anemometer, an experimental device is established, which consists of an anemometer sensor, a sound sensor, a microphone, paper strips, a paper cup, and sonic acquisition software. It shows…

  3. Fiber Laser for Wind Speed Measurements

    DEFF Research Database (Denmark)

    Olesen, Anders Sig

    This PhD thesis evaluates the practical construction and use of a Frequency Stepped Pulse Train modulated coherent Doppler wind lidar (FSPT lidar) for wind speed measurement. The concept of Doppler lidar is introduced as a means to measure line of sight wind speed by the Doppler shift of reflected...... light from aerosols. Central concepts are introduced and developed, i.a. heterodyne detection, carrier-to-noise ratio, probe length, measuring distance, and velocity precision. On this basis the concepts of a FSPT lidar are introduced and its general setup explained. The Lightwave Synthesized Frequency...... Sweeper (LSFS) is introduced and analyzed as a light source for the FSPT lidar. The setup of the LSFS is discussed, and the necessary concepts for modeling and analyzing LSFS noise are developed. The model and measurements are then used to discuss the growth of optical noise in the LSFS and the impact...

  4. Short-term wind speed estimation based on weather data

    OpenAIRE

    ÖZGÖNENEL, Okan; THOMAS, David W. P.

    2012-01-01

    For accurate and efficient use of wind power, it is important to know the statistical characteristics, availability, diurnal variation, and prediction of wind speed. Prediction of wind power permits the scheduling of the connection or the disconnection of wind turbines to achieve optimal operating costs. In this paper, a simple and accurate method for predicting wind speed based on weather-sensitive data is presented. The proposed wind speed prediction system is cost-effective and o...

  5. The wind speed profile at offshore wind farm sites

    Science.gov (United States)

    Lange, B.; Larsen, S. E.; Højstrup, J.; Barthelmie, R.

    2003-04-01

    The first large offshore wind farms are in the planning phase in several countries in Europe. Their economic viability depends on the favourable wind conditions compared to sites on land. The higher energy yield has to compensate the additional installation and maintenance cost. For project planning and siting a reliable prediction of the wind resource is therefore crucial. For turbine design the wind shear of the marine surface layer is an important design parameter, especially since the growing rotor diameter makes turbines more vulnerable for spatial wind speed variations. Compared to land surfaces the roughness of water is very low. It is commonly described either as a constant (as in the wind resource estimation program WAsP) or by means of the Charnock approach, relating sea surface roughness and friction velocity. While this relation works well for the open oceans it has been found inappropriate for coastal areas where waves are not fully developed. Information about the wave field is needed to model the sea surface roughness more accurately (see e.g. Johnson et al. (1998)). The atmospheric stability differs greatly between land and water areas. It is more important offshore compared to land sites due to the low surface roughness of water. The main influence of the atmospheric stability is on the vertical momentum transport, which is reflected in the vertical wind speed profile. It is usually described with Monin-Obukhov similarity theory. However, other effects not described by this approach might also play an important role: For offshore flow the flow regime at coastal sites is affected by the land-sea discontinuity (Højstrup, 1999). An internal boundary layer develops at the coastline and an inhomogeneous flow field might develop in the coastal zone, especially in stable stratification (see e.g. (Smedman et al. (1997)) Recent data from the measurement at Rødsand, 10 km off the Danish coast in the Baltic Sea, include simultaneous wind and wave data from

  6. Monitoring of wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    White, Jonathan R.; Adams, Douglas E.; Paquette, Josh

    2017-07-25

    Method and apparatus for determining the deflection or curvature of a rotating blade, such as a wind turbine blade or a helicopter blade. Also, methods and apparatus for establishing an inertial reference system on a rotating blade.

  7. Torque- and Speed Control of a Pitch Regulated Wind Turbine

    Energy Technology Data Exchange (ETDEWEB)

    Rasila, Mika

    2003-07-01

    Variable speed operated wind turbines has the potential to reduce fatigue loads, compared to fixed speed wind turbines. With pitch controllable rotor blades limitation of the power at high wind speeds is obtained. The thesis describes different controlling aspects concerning wind turbines and how these together can be used to optimize the system's performance. Torque control is used in order to achieve reduction on the mechanical loads on the drive-train for low wind speeds and limitation of power output for high wind speeds. In the high wind speed interval torque control is effective in order to limit the output power if a sufficiently fast pitch actuator is used. In the middle wind speed interval filter utilization can be used to give a reference signal to the controller in order to reduce speed and torque variations.

  8. Interval forecasts of a novelty hybrid model for wind speeds

    OpenAIRE

    Shanshan Qin; Feng Liu; Jianzhou Wang; Yiliao Song

    2015-01-01

    The utilization of wind energy, as a booming technology in the field of renewable energies, has been highly regarded around the world. Quantification of uncertainties associated with accurate wind speed forecasts is essential for regulating wind power generation and integration. However, it remains difficult work primarily due to the stochastic and nonlinear characteristics of wind speed series. Traditional models for wind speed forecasting mostly focus on generating certain predictive values...

  9. Multistep Wind Speed Forecasting Based on Wavelet and Gaussian Processes

    OpenAIRE

    Niya Chen; Zheng Qian; Xiaofeng Meng

    2013-01-01

    Accurate wind speed forecasts are necessary for the safety and economy of the renewable energy utilization. The wind speed forecasts can be obtained by statistical model based on historical data. In this paper, a novel W-GP model (wavelet decomposition based Gaussian process learning paradigm) is proposed for short-term wind speed forecasting. The nonstationary and nonlinear original wind speed series is first decomposed into a set of better-behaved constitutive subseries by wavelet decomposi...

  10. Control of Variable Speed Variable Pitch Wind Turbine at Above and Below Rated Wind Speed

    Directory of Open Access Journals (Sweden)

    Saravanakumar Rajendran

    2014-01-01

    Full Text Available The paper presents a nonlinear approach to wind turbine (WT using two-mass model. The main aim of the controller in the WT is to maximize the energy output at varying wind speed. In this work, a combination of linear and nonlinear controllers is adapted to variable speed variable pitch wind turbines (VSVPWT system. The major operating regions of the WT are below (region 2 and above rated (region 3 wind speed. In these regions, generator torque control (region 2 and pitch control (region 3 are used. The controllers in WT are tested for below and above rated wind speed for step and vertical wind speed profile. The performances of the controllers are analyzed with nonlinear FAST (Fatigue, Aerodynamics, Structures, and Turbulence WT dynamic simulation. In this paper, two nonlinear controllers, that is, sliding mode control (SMC and integral sliding mode control (ISMC, have been applied for region 2, whereas for pitch control in region 3 conventional PI control is used. In ISMC, the sliding manifold makes use of an integral action to show effective qualities of control in terms of the control level reduction and sliding mode switching control minimization.

  11. Wind speed forecasting in the central California wind resource area

    Energy Technology Data Exchange (ETDEWEB)

    McCarthy, E.F. [Wind Economics & Technology, Inc., Martinez, CA (United States)

    1997-12-31

    A wind speed forecasting program was implemented in the summer seasons of 1985 - 87 in the Central California Wind Resource Area (WRA). The forecasting program is designed to use either meteorological observations from the WRA and local upper air observations or upper air observations alone to predict the daily average windspeed at two locations. Forecasts are made each morning at 6 AM and are valid for a 24 hour period. Ease of use is a hallmark of the program as the daily forecast can be made using data entered into a programmable HP calculator. The forecasting program was the first step in a process to examine whether the electrical energy output of an entire wind power generation facility or defined subsections of the same facility could be predicted up to 24 hours in advance. Analysis of the results of the summer season program using standard forecast verification techniques show the program has skill over persistence and climatology.

  12. Comparison of SAR Wind Speed Retrieval Algorithms for Evaluating Offshore Wind Energy Resources

    DEFF Research Database (Denmark)

    Kozai, K.; Ohsawa, T.; Takeyama, Y.

    2010-01-01

    Envisat/ASAR-derived offshore wind speeds and energy densities based on 4 different SAR wind speed retrieval algorithms (CMOD4, CMOD-IFR2, CMOD5, CMOD5.N) are compared with observed wind speeds and energy densities for evaluating offshore wind energy resources. CMOD4 ignores effects of atmospheric...

  13. Automated wind-icing monitoring system

    Energy Technology Data Exchange (ETDEWEB)

    Horokhov, Y.; Nekrasov, Y.; Turbin, S. [Donbas National Academy of Civil Engineering and Architecture, Makeyevka, Donetsk (Ukraine); Grimud, G. [NEC Ukrenergo, Kiev (Ukraine)

    2005-07-01

    The development of automated wind-icing monitoring systems (AWIMS) has increased the operational reliability of existing overhead lines through a more accurate prediction of icing events in the Ukraine. The systems are capable of operating without the presence of personnel, and allow operators to immediately obtain information about icing processes. The systems provide statistically significant sets of data for determining and predicting loading conditions, as well as combining measurements of icing mass, wind speed and direction, temperature and humidity. An outline of the principles of AWIMS was presented in paper, as well as a description of the system's architecture and operating principles. The monitoring system consists of an ice mass measuring device; a strain gauge sensor; a photoelectric pickup to determine perpendicular mean wind direction; and a wire simulator. The measuring devices are installed 10 meters above ground. Data is transmitted every 30 minutes to a central information office, where information is processed and stored. Details of the ultrasonic anemometer for wind measurements as well as the devices used for humidity and temperature measurement were presented. The AWIMS computer software measures 6 climatic parameters: wind speed; wind direction; air temperature; humidity; icing mass; and wind pressure on ice-covered wires. Results of a series of tests were presented which included a weather station data analysis and a comparison of the AWIMS with standard climatic loads. An analysis of overhead line failure statistical data was also conducted. Spatial icing distributions were used to calculate the threshold sensitivity for the AWIMS. As estimation of overhead lines density per square kilometer showed was made to determine placement of the systems. It was concluded that 8 more AWIMS will be installed in the following year. 3 refs., 10 figs.

  14. An Analysis of Variable-Speed Wind Turbine Power-Control Methods with Fluctuating Wind Speed

    Directory of Open Access Journals (Sweden)

    Seung-Il Moon

    2013-07-01

    Full Text Available Variable-speed wind turbines (VSWTs typically use a maximum power-point tracking (MPPT method to optimize wind-energy acquisition. MPPT can be implemented by regulating the rotor speed or by adjusting the active power. The former, termed speed-control mode (SCM, employs a speed controller to regulate the rotor, while the latter, termed power-control mode (PCM, uses an active power controller to optimize the power. They are fundamentally equivalent; however, since they use a different controller at the outer control loop of the machine-side converter (MSC controller, the time dependence of the control system differs depending on whether SCM or PCM is used. We have compared and analyzed the power quality and the power coefficient when these two different control modes were used in fluctuating wind speeds through computer simulations. The contrast between the two methods was larger when the wind-speed fluctuations were greater. Furthermore, we found that SCM was preferable to PCM in terms of the power coefficient, but PCM was superior in terms of power quality and system stability.

  15. Wake flow characteristics at high wind speed

    DEFF Research Database (Denmark)

    Aagaard Madsen, Helge; Larsen, Torben J.; Larsen, Gunner Chr.

    2016-01-01

    power. In the present study we simulate the wake flow for a row of turbines with the wind aligned with the row using a simplified approach. The velocity deficit, being a function of the thrust coefficient, is simulated based on the BEM solution for wake expansion. An axis-symmetric boundary layer...... equation model (the same as implemented in the DWM model) is subsequently used to develop the deficit down to the next turbine, and then the approach is successively repeated. Simulation results for four different spacing’s in a row with eight turbines show that there are two major flow regimes...... in the intersection region between the two flow regimes a strong variation in power and thrust occur, e.g. going from almost zero power to rated power for a wind speed change of 4m/s. Another result is that the inflow profile to the last turbine in the row at a wind speed of 16m/s for a spacing of 3D shows...

  16. Photovoltaic Module Thermal/Wind Performance: Long-Term Monitoring and Model Development for Energy Rating

    Energy Technology Data Exchange (ETDEWEB)

    TamizhMani, G.; Ji, L.; Tang, Y.; Petacci, L.; Osterwald, C.

    2003-06-01

    In order to predict the energy production of photovoltaic (PV) modules, it is necessary to predict the module temperature as a function of ambient temperature, wind speed, wind direction, total irradiance, and relative humidity. This paper presents a mathematical model to predict the module temperature based on the field monitored real data of module temperature, ambient temperature, wind speed, wind direction and relative humidity.

  17. Wind speed change regionalization in China(1961-2012)

    Institute of Scientific and Technical Information of China (English)

    SHI; Pei-Jun; ZHANG; Gang-Feng; KONG; Feng; YE; Qian

    2015-01-01

    This research quantitatively recognized the wind speed change using wind speed trend and trend of wind speed variability from 1961 to 2012 and regionalized the wind speed change on a county-level basis.The mean wind speed observation data and linear fitting method were used.The findings suggested that level-I regionalization includes six zones according to wind speed trend value in different regions,viz.Northeast ChinaeNorth China substantial declining zone,EasteCentral China declining zone,Southeast China slightly declining zone,Southwest China very slightly declining zone,Northwest China declining zone,and QinghaieTibetan Plateau slightly declining zone.Level-II regionalization divides China into twelve regions based on trend of wind speed variability and the level-I regionalization results.

  18. Extreme wind speeds in mixed climates revisited

    Energy Technology Data Exchange (ETDEWEB)

    Cook, Nicholas J.; Ian Harris, R. [Anemos Associates Ltd., 14 The Chestnuts, Hemel Hempstead HP3 0DZ (United Kingdom); Whiting, Richard [Department of Aerospace, University of Bristol, Bristol BS8 1TR (United Kingdom)

    2003-02-01

    The methodology for the analysis of extreme wind speeds in mixed climates originally proposed in 1978 by Gomes and Vickery is updated to take advantage of recent improvements in methodology and available data records. The revised methodology is demonstrated for two sites in Australia: Onslow and Brisbane. This work shows that the observed curvature in the upper tail is due to incomplete convergence to the Fisher-Tippett Type 1 asymptote and is not an indicator of Type 3 behaviour as sometimes supposed. It is also shown that moving from a reference epoch of 1 year to an epoch of 50 years frees the method from most of the rate-dependent assumptions, and simplifies the problem to a single, dominant wind mechanism.

  19. Monitoring speed before and during a speed publicity campaign.

    NARCIS (Netherlands)

    Schagen, I.N.L.G. van Commandeur, J.J.F. Goldenbeld, C. & Stipdonk, H.

    2016-01-01

    Driving speeds were monitored during a period of 16 weeks encompassing different stages of an anti-speeding campaign in the Netherlands. This campaign targeted speed limit violations in built-up areas. The observation periods differed in terms of intensity and media used for the campaign. Small road

  20. Swatch Testing at Elevated Wind Speeds

    Science.gov (United States)

    2014-07-17

    were less than 0.2°F. Experimental uncertainty was determined in a method outlined in reference 8 (Barlow, Rae and Pope) and the measured velocity...Apr 2013. 8. Barlow, J., B., Rae , W.H., Pope, A. Low-Speed Wind Tunnel Testing, 3rd Edition, Wiley, New York, 1999. 9. Akima, H., "A New...10. Model 3936 SMPS (Scanning Mobility Particle Sizer) Instruction Manual , TSI Part Number 1933796, Apr 1999. 11. He M., Dhaniyala, S., “A

  1. Further development of an improved altimeter wind speed algorithm

    Science.gov (United States)

    Chelton, Dudley B.; Wentz, Frank J.

    1986-01-01

    A previous altimeter wind speed retrieval algorithm was developed on the basis of wind speeds in the limited range from about 4 to 14 m/s. In this paper, a new approach which gives a wind speed model function applicable over the range 0 to 21 m/s is used. The method is based on comparing 50 km along-track averages of the altimeter normalized radar cross section measurements with neighboring off-nadir scatterometer wind speed measurements. The scatterometer winds are constructed from 100 km binned measurements of radar cross section and are located approximately 200 km from the satellite subtrack. The new model function agrees very well with earlier versions up to wind speeds of 14 m/s, but differs significantly at higher wind speeds. The relevance of these results to the Geosat altimeter launched in March 1985 is discussed.

  2. Design of Wind Turbine Vibration Monitoring System

    National Research Council Canada - National Science Library

    Shoubin Wang; Wei Gong; Gang Su; Hongyue Sun

    2013-01-01

    In order to ensure safety of wind turbine operation and to reduce the occurrence of faults as well as to improve the reliability of wind turbine operation, a vibration monitoring for wind turbine is developed...

  3. Model of a synthetic wind speed time series generator

    DEFF Research Database (Denmark)

    Negra, N.B.; Holmstrøm, O.; Bak-Jensen, B.

    2008-01-01

    of possible wind conditions. If these information are not available, synthetic wind speed time series may be a useful tool as well, but their generator must preserve statistical and stochastic features of the phenomenon. This paper deals with this issue: a generator for synthetic wind speed time series...

  4. Pitch Angle Control for Variable Speed Wind Turbines

    DEFF Research Database (Denmark)

    Chen, Zhe; Zhang, Jianzhong; Cheng, M;

    2008-01-01

    controller, the mathematical model of the system should be known well. A fuzzy logic pitch angle controller is developed in this paper, in which it does not need well known about the system and the mean wind speed is used to compensate the non-linear sensitivity. The fuzzy logic control strategy may have......Pitch angle control is the most common means for adjusting the aerodynamic torque of the wind turbine when wind speed is above rated speed and various controlling variables may be chosen, such as wind speed, generator speed and generator power. As conventional pitch control usually use PI...

  5. Comparison of NWP wind speeds and directions to measured wind speeds and directions

    DEFF Research Database (Denmark)

    Astrup, Poul; Mikkelsen, Torben

    Numerical Weather Predictions (NWP) of wind speed and direction has been compared to measurements for seven German sites for nuclear power plants, and for Risø, the site of the Danish nuclear research reactors now being decommissioned . For the German sites the data cover approximately three month...

  6. Effectiveness of Changing Wind Turbine Cut-in Speed to Reduce Bat Fatalities at Wind Facilities

    Energy Technology Data Exchange (ETDEWEB)

    Huso, Manuela M. P. [Oregon State Univ., Corvallis, OR (United States); Hayes, John P. [Univ. of Florida, Gainesville, FL (United States)

    2009-04-01

    This report details an experiment on the effectiveness of changing wind turbine cut-in speed on reducing bat fatality from wind turbines at the Casselman Wind Project in Somerset County, Pennsylvania.

  7. Time Series Model of Wind Speed for Multi Wind Turbines based on Mixed Copula

    Directory of Open Access Journals (Sweden)

    Nie Dan

    2016-01-01

    Full Text Available Because wind power is intermittent, random and so on, large scale grid will directly affect the safe and stable operation of power grid. In order to make a quantitative study on the characteristics of the wind speed of wind turbine, the wind speed time series model of the multi wind turbine generator is constructed by using the mixed Copula-ARMA function in this paper, and a numerical example is also given. The research results show that the model can effectively predict the wind speed, ensure the efficient operation of the wind turbine, and provide theoretical basis for the stability of wind power grid connected operation.

  8. A nonlinear dynamics approach for incorporating wind-speed patterns into wind-power project evaluation.

    Science.gov (United States)

    Huffaker, Ray; Bittelli, Marco

    2015-01-01

    Wind-energy production may be expanded beyond regions with high-average wind speeds (such as the Midwest U.S.A.) to sites with lower-average speeds (such as the Southeast U.S.A.) by locating favorable regional matches between natural wind-speed and energy-demand patterns. A critical component of wind-power evaluation is to incorporate wind-speed dynamics reflecting documented diurnal and seasonal behavioral patterns. Conventional probabilistic approaches remove patterns from wind-speed data. These patterns must be restored synthetically before they can be matched with energy-demand patterns. How to accurately restore wind-speed patterns is a vexing problem spurring an expanding line of papers. We propose a paradigm shift in wind power evaluation that employs signal-detection and nonlinear-dynamics techniques to empirically diagnose whether synthetic pattern restoration can be avoided altogether. If the complex behavior of observed wind-speed records is due to nonlinear, low-dimensional, and deterministic system dynamics, then nonlinear dynamics techniques can reconstruct wind-speed dynamics from observed wind-speed data without recourse to conventional probabilistic approaches. In the first study of its kind, we test a nonlinear dynamics approach in an application to Sugarland Wind-the first utility-scale wind project proposed in Florida, USA. We find empirical evidence of a low-dimensional and nonlinear wind-speed attractor characterized by strong temporal patterns that match up well with regular daily and seasonal electricity demand patterns.

  9. Can wind help explain seasonal differences in avian migration speed?

    NARCIS (Netherlands)

    Kemp, M.U.; Shamoun-Baranes, J.; van Gasteren, H.; Bouten, W.; van Loon, E.E.

    2010-01-01

    A bird's ground speed is influenced by the wind conditions it encounters. Wind conditions, although variable, are not entirely random. Instead, wind exhibits persistent spatial and temporal dynamics described by the general circulation of the atmosphere. As such, in certain geographical areas wind's

  10. An Appropriate Wind Model for Wind Integrated Power Systems Reliability Evaluation Considering Wind Speed Correlations

    Directory of Open Access Journals (Sweden)

    Rajesh Karki

    2013-02-01

    Full Text Available Adverse environmental impacts of carbon emissions are causing increasing concerns to the general public throughout the world. Electric energy generation from conventional energy sources is considered to be a major contributor to these harmful emissions. High emphasis is therefore being given to green alternatives of energy, such as wind and solar. Wind energy is being perceived as a promising alternative. This source of energy technology and its applications have undergone significant research and development over the past decade. As a result, many modern power systems include a significant portion of power generation from wind energy sources. The impact of wind generation on the overall system performance increases substantially as wind penetration in power systems continues to increase to relatively high levels. It becomes increasingly important to accurately model the wind behavior, the interaction with other wind sources and conventional sources, and incorporate the characteristics of the energy demand in order to carry out a realistic evaluation of system reliability. Power systems with high wind penetrations are often connected to multiple wind farms at different geographic locations. Wind speed correlations between the different wind farms largely affect the total wind power generation characteristics of such systems, and therefore should be an important parameter in the wind modeling process. This paper evaluates the effect of the correlation between multiple wind farms on the adequacy indices of wind-integrated systems. The paper also proposes a simple and appropriate probabilistic analytical model that incorporates wind correlations, and can be used for adequacy evaluation of multiple wind-integrated systems.

  11. Monitoring speed before and during a speed publicity campaign.

    Science.gov (United States)

    van Schagen, Ingrid; Commandeur, Jacques J F; Goldenbeld, Charles; Stipdonk, Henk

    2016-12-01

    Driving speeds were monitored during a period of 16 weeks encompassing different stages of an anti-speeding campaign in the Netherlands. This campaign targeted speed limit violations in built-up areas. The observation periods differed in terms of intensity and media used for the campaign. Small road-side radars, mounted in light poles, were used and registered the speeds on 20 locations in built-up areas. Speeds of over 10 million vehicles were measured. Ten locations had a posted speed limit of 50km/h; the other ten had a posted speed limit of 30km/h. Posters were placed at half of each group of locations to remind drivers of the speed limit. The average speed on the 50km/h roads was 46.2km/h, and 36.1km/h on the 30km/h roads. The average proportions of vehicles exceeding the speed limit were 33.3% and 70.1% respectively. For the 30km/h roads, the data shows differences in speed and speeding behaviour between the six distinguished observation periods, but overall these differences cannot be logically linked to the contents of the phases and, hence, cannot be explained as an effect of the campaign. The only exception was an effect of local speed limit reminders on the 30km/h roads. This effect, however, was temporary and had disappeared within a week.

  12. Wind speed prediction using statistical regression and neural network

    Indian Academy of Sciences (India)

    Makarand A Kulkarni; Sunil Patil; G V Rama; P N Sen

    2008-08-01

    Prediction of wind speed in the atmospheric boundary layer is important for wind energy assess- ment,satellite launching and aviation,etc.There are a few techniques available for wind speed prediction,which require a minimum number of input parameters.Four different statistical techniques,viz.,curve fitting,Auto Regressive Integrated Moving Average Model (ARIMA),extrapolation with periodic function and Artificial Neural Networks (ANN)are employed to predict wind speed.These methods require wind speeds of previous hours as input.It has been found that wind speed can be predicted with a reasonable degree of accuracy using two methods,viz.,extrapolation using periodic curve fitting and ANN and the other two methods are not very useful.

  13. Determination trends and abnormal seasonal wind speed in Iraq

    Energy Technology Data Exchange (ETDEWEB)

    Hassoon, Ahmed F. [Department of Atmospheric Sciences, College of Science, AL- Mustansiriyah University, Baghdad (Iraq)

    2013-07-01

    Monthly observed wind speed data at four weather stations (Baghdad, Mosul, Basra, Rutba) at 10m above surface were used to explore the temporal variations of the wind speed (1971-2000) in Iraq. There are different methods to analyze wind speed variation data, but the time series are one of the powerful analysis methods to diagnose the seasonal wind speed anomaly. The results show most high abnormal data is found in summer seasons in all the stations of study, where it concentrated at 1975, 1976, 1978,1996-1995, 2000. Rutba station is different where its high deviation about annual average at nearly all the seasons, in this station there are trends in seasonal wind towards decreases in all the seasons, for example in winter it reached to about 0.046m/s.a-1, while in other stations Mosul and Basra there increases in annual seasonal wind speed trends in seasons spring, summer, autumn where its reached higher value at summer in Basra about 0.0482m/s.a-1. The second method to determine abnormal annual seasonal wind speed is through comparison seasonal average wind speed, where the average wind speed at the seasons summer and spring in Baghdad and Basra station have very high averages at nearly all years, this cannot see in Mosul and Rutba, in Rutba the seasonal average is intersected with each other, summer and spring is not have greater seasonal average in this station.

  14. Multistep Wind Speed Forecasting Based on Wavelet and Gaussian Processes

    Directory of Open Access Journals (Sweden)

    Niya Chen

    2013-01-01

    Full Text Available Accurate wind speed forecasts are necessary for the safety and economy of the renewable energy utilization. The wind speed forecasts can be obtained by statistical model based on historical data. In this paper, a novel W-GP model (wavelet decomposition based Gaussian process learning paradigm is proposed for short-term wind speed forecasting. The nonstationary and nonlinear original wind speed series is first decomposed into a set of better-behaved constitutive subseries by wavelet decomposition. Then these sub-series are forecasted respectively by GP method, and the forecast results are summed to formulate an ensemble forecast for original wind speed series. Therefore, the previous process which obtains wind speed forecast result is named W-GP model. Finally, the proposed model is applied to short-term forecasting of the mean hourly and daily wind speed for a wind farm located in southern China. The prediction results indicate that the proposed W-GP model, which achieves a mean 13.34% improvement in RMSE (Root Mean Square Error compared to persistence method for mean hourly data and a mean 7.71% improvement for mean daily wind speed data, shows the best forecasting accuracy among several forecasting models.

  15. Application-dependent Probability Distributions for Offshore Wind Speeds

    Science.gov (United States)

    Morgan, E. C.; Lackner, M.; Vogel, R. M.; Baise, L. G.

    2010-12-01

    The higher wind speeds of the offshore environment make it an attractive setting for future wind farms. With sparser field measurements, the theoretical probability distribution of short-term wind speeds becomes more important in estimating values such as average power output and fatigue load. While previous studies typically compare the accuracy of probability distributions using R2, we show that validation based on this metric is not consistent with validation based on engineering parameters of interest, namely turbine power output and extreme wind speed. Thus, in order to make the most accurate estimates possible, the probability distribution that an engineer picks to characterize wind speeds should depend on the design parameter of interest. We introduce the Kappa and Wakeby probability distribution functions to wind speed modeling, and show that these two distributions, along with the Biweibull distribution, fit wind speed samples better than the more widely accepted Weibull and Rayleigh distributions based on R2. Additionally, out of the 14 probability distributions we examine, the Kappa and Wakeby give the most accurate and least biased estimates of turbine power output. The fact that the 2-parameter Lognormal distribution estimates extreme wind speeds (i.e. fits the upper tail of wind speed distributions) with least error indicates that not one single distribution performs satisfactorily for all applications. Our use of a large dataset composed of 178 buoys (totaling ~72 million 10-minute wind speed observations) makes these findings highly significant, both in terms of large sample size and broad geographical distribution across various wind regimes. Boxplots of R2 from the fit of each of the 14 distributions to the 178 boy wind speed samples. Distributions are ranked from left to right by ascending median R2, with the Biweibull having the closest median to 1.

  16. Short-Term Wind Speed Forecasting for Power System Operations

    KAUST Repository

    Zhu, Xinxin

    2012-04-01

    The emphasis on renewable energy and concerns about the environment have led to large-scale wind energy penetration worldwide. However, there are also significant challenges associated with the use of wind energy due to the intermittent and unstable nature of wind. High-quality short-term wind speed forecasting is critical to reliable and secure power system operations. This article begins with an overview of the current status of worldwide wind power developments and future trends. It then reviews some statistical short-term wind speed forecasting models, including traditional time series approaches and more advanced space-time statistical models. It also discusses the evaluation of forecast accuracy, in particular, the need for realistic loss functions. New challenges in wind speed forecasting regarding ramp events and offshore wind farms are also presented. © 2012 The Authors. International Statistical Review © 2012 International Statistical Institute.

  17. Potential of Offshore Wind Energy and Extreme Wind Speed Forecasting on the West Coast of Taiwan

    Directory of Open Access Journals (Sweden)

    Pei-Chi Chang

    2015-02-01

    Full Text Available It is of great importance and urgency for Taiwan to develop offshore wind power. However, relevant data on offshore wind energy resources are limited. This study imported wind speeds measured by a tidal station and a buoy into the software WAsP to estimate the high-altitude wind speeds in the two areas. A light detection and ranging (Lidar system was set up near the tidal station and buoy. High-altitude wind speeds measured by the Lidar system were compared with the WAsP-estimated values, and it was discovered that the two data sets were consistent. Then, long-term wind speed data observed by buoys and tidal stations at various locations were imported into WAsP to forecast wind speeds at heights of 55–200 m on the west coast of Taiwan. The software WAsP Engineering was used to analyze the extreme wind speeds in the same areas. The results show that wind speeds at 100 m are approximately 9.32–11.24 m/s, which means that the coastal areas of west Taiwan are rich in wind energy resources. When a long-term 10-min average wind speed is used, the extreme wind speed on the west coast is estimated to be between 36.4 and 55.3 m/s.

  18. Modeling of the dynamics of wind to power conversion including high wind speed behavior

    DEFF Research Database (Denmark)

    Litong-Palima, Marisciel; Bjerge, Martin Huus; Cutululis, Nicolaos Antonio

    2016-01-01

    of power system studies, but the idea of the proposed wind turbine model is to include the main dynamic effects in order to have a better representation of the fluctuations in the output power and of the fast power ramping especially because of high wind speed shutdowns of the wind turbine. The high wind......This paper proposes and validates an efficient, generic and computationally simple dynamic model for the conversion of the wind speed at hub height into the electrical power by a wind turbine. This proposed wind turbine model was developed as a first step to simulate wind power time series...... for power system studies. This paper focuses on describing and validating the single wind turbine model, and is therefore neither describing wind speed modeling nor aggregation of contributions from a whole wind farm or a power system area. The state-of-the-art is to use static power curves for the purpose...

  19. Investigation of Wind Speed Persistence Over Marmara Region

    Science.gov (United States)

    Özgür, Evren; Koçak, Kasım

    2016-04-01

    Persistence is a measure of continuity of a variable over a period of time at any location. This definition implies that wind speed persistence means a positive serial correlation in a time series. In literature, there are numerous methods for measuring wind speed persistence. In this study, wind speed persistence were obtained for 19 stations located in Marmara Region by using two different methods. Daily wind speed data, taken from Turkish State Meteorological Service, were used in the study. The observation period was taken to be 1965-2014 for all stations. The methods used in the study are directional statistical method and wind speed duration curves approach. In directional statistical method, individual dates of winds are defined as directional variables; then, directional mean and variance are calculated. Wind dates are being converted to angular values and these days are being considered as a unit vector which has direction θ. In polar coordinate, the measures of directional mean and variance have been expressed as a vector with direction θmean and magnitude r. The r value can be considered as a measure of persistence. The wind speed duration curve is simply the cumulative distribution function of the wind speed in a certain period of time. In other words, it is the graphical representation of wind speed and percentage of exceedence time for a predefined threshold wind speed value in the same graphic. As a threshold wind speed, lower quartile (q0.25) value of ranked wind speed data were selected. In application, total time period was divided into five subperiods and changes of persistence in wind speeds as far as subperiods were presented. Persistence can be used in different kinds of study areas such as control of forest fires, dispersion of air pollutants, calculation of wind energy potential, ventilation of a city, etc. The results of this analysis showed that the proposed methods can be used as an alternative approach to determine whether a given time

  20. Wind Turbine Manufacturing Process Monitoring

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-04-26

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

  1. The influence of humidity fluxes on offshore wind speed profiles

    DEFF Research Database (Denmark)

    Barthelmie, Rebecca Jane; Sempreviva, Anna Maria; Pryor, Sara

    2010-01-01

    Wind energy developments offshore focus on larger turbines to keep the relative cost of the foundation per MW of installed capacity low. Hence typical wind turbine hub-heights are extending to 100 m and potentially beyond. However, measurements to these heights are not usually available, requiring...... extrapolation from lower measurements. With humid conditions and low mechanical turbulence offshore, deviations from the traditional logarithmic wind speed profile become significant and stability corrections are required. This research focuses on quantifying the effect of humidity fluxes on stability corrected...... wind speed profiles. The effect on wind speed profiles is found to be important in stable conditions where including humidity fluxes forces conditions towards neutral. Our results show that excluding humidity fluxes leads to average predicted wind speeds at 150 m from 10 m which are up to 4% higher...

  2. The influence of humidity fluxes on offshore wind speed profiles

    Directory of Open Access Journals (Sweden)

    R. J. Barthelmie

    2010-05-01

    Full Text Available Wind energy developments offshore focus on larger turbines to keep the relative cost of the foundation per MW of installed capacity low. Hence typical wind turbine hub-heights are extending to 100 m and potentially beyond. However, measurements to these heights are not usually available, requiring extrapolation from lower measurements. With humid conditions and low mechanical turbulence offshore, deviations from the traditional logarithmic wind speed profile become significant and stability corrections are required. This research focuses on quantifying the effect of humidity fluxes on stability corrected wind speed profiles. The effect on wind speed profiles is found to be important in stable conditions where including humidity fluxes forces conditions towards neutral. Our results show that excluding humidity fluxes leads to average predicted wind speeds at 150 m from 10 m which are up to 4% higher than if humidity fluxes are included, and the results are not very sensitive to the method selected to estimate humidity fluxes.

  3. Pitch Angle Control of Variable Speed Wind Turbine

    Directory of Open Access Journals (Sweden)

    Yousif El-Tous

    2008-01-01

    Full Text Available The aim of this study is to design a simple controller to maximize the extracted energy of wind turbines. In this study the pitch angle control of variable speed wind turbine is investigated. In particular, it concentrates on the extraction of maximum available energy, reduction of torque and output power variations, which gives stresses in the gearbox and mechanical structure. The control concentrates on separate wind speed internals as well as on whole wind speed region. It is found that the control structures varies substantially between the wind speed regions. Two different control systems are compared. The results show that pitch actuator with three levels of pitching speed have better response.

  4. Prediction models for wind speed at turbine locations in a wind farm

    DEFF Research Database (Denmark)

    Knudsen, Torben; Bak, Thomas; Soltani, Mohsen

    2011-01-01

    on the result related to effective wind speed, it is possible to predict wind speeds at neighboring turbines, with a separation of over 700 m, up to 1 min ahead reducing the error by 30% compared with a persistence method. The methodological results are demonstrated on data from an off-shore wind farm...

  5. Actuator disk model of wind farms based on the rotor average wind speed

    DEFF Research Database (Denmark)

    Han, Xing Xing; Xu, Chang; Liu, De You;

    2016-01-01

    Due to difficulty of estimating the reference wind speed for wake modeling in wind farm, this paper proposes a new method to calculate the momentum source based on the rotor average wind speed. The proposed model applies volume correction factor to reduce the influence of the mesh recognition...

  6. Assessment of C-Type Darrieus Wind Turbine Under Low Wind Speed Condition

    Science.gov (United States)

    Misaran, M. S.; Rahman, Md. M.; Muzammil, W. K.; Ismail, M. A.

    2017-07-01

    Harvesting wind energy in in a low wind speed region is deem un-economical if not daunting task. Study shows that a minimum cut in speed of 3.5 m/s is required to extract a meaningful wind energy for electricity while a mean speed of 6 m/s is preferred. However, in Malaysia the mean speed is at 2 m/s with certain potential areas having 3 m/s mean speed. Thus, this work aims to develop a wind turbine that able to operate at lower cut-in speed and produce meaningful power for electricity generation. A C-type Darrieus blade is selected as it shows good potential to operate in arbitrary wind speed condition. The wind turbine is designed and fabricated in UMS labs while the performance of the wind turbine is evaluated in a simulated wind condition. Test result shows that the wind turbine started to rotate at 1 m/s compared to a NACA 0012 Darrieus turbine that started to rotate at 3 m/s. The performance of the turbine shows that it have good potential to be used in an intermittent arbitrary wind speed condition as well as low mean wind speed condition.

  7. Reducing the uncertainty in wind speed estimations near the coast

    Science.gov (United States)

    Floors, Rogier; Hahmann, Andrea N.; Karagali, Ioanna; Vasiljevic, Nikola; Lea, Guillaume; Simon, Elliot; Courtney, Michael; Ahsbahs, Tobias; Bay Hasager, Charlotte; Badger, Merete; Peña, Alfredo

    2016-04-01

    Many countries plan to meet renewable energy targets by installing near-shore wind farms, because of the high offshore wind speeds and good grid connectivity. Because of the strong relation between mean wind speed and the annual energy production, there is an interest in reducing uncertainty of the estimation of the wind speed in these coastal areas. The RUNE project aims to provide recommendations on the use of lidar systems and mesoscale models results to find the most effective (cost vs. accuracy) solution of estimating near-shore wind resources. Here we show some first results of the RUNE measuring campaign at the west coast of Jutland that started in December 2015. In this campaign, a long-range WindScanner system (a multi-lidar instrumentation) was used simultaneously with measurements from several vertical profiling lidars, a meteorological mast and an offshore buoy. These measurements result in a detailed picture of the flow in a transect across the coastline from approximately 5 km offshore up to 3 km inland. The wind speed obtained from a lidar in a sector-scanning mode and from two time-synchronized lidars that were separated horizontally but focused in the same point, will be compared. Furthermore it will be shown how the resulting horizontal wind speed transects compare with the wind speed measurements from the vertical profiling lidars and the meteorological mast. The behaviour of the coastal gradient in wind speed in this area is discussed. Satellite data for the wind over the RUNE measurement area were also collected. Synthetic Aperture Radar (SAR) winds from Sentinel-1 and TerraSAR-X were retrieved at different spatial resolutions. Advanced Scatterometer (ASCAT) swath winds were obtained from both METOP-A and B platforms. These were used for direct comparisons with the lidar in sector scanning mode.

  8. Hourly Wind Speed Interval Prediction in Arid Regions

    Science.gov (United States)

    Chaouch, M.; Ouarda, T.

    2013-12-01

    The long and extended warm and dry summers, the low rate of rain and humidity are the main factors that explain the increase of electricity consumption in hot arid regions. In such regions, the ventilating and air-conditioning installations, that are typically the most energy-intensive among energy consumption activities, are essential for securing healthy, safe and suitable indoor thermal conditions for building occupants and stored materials. The use of renewable energy resources such as solar and wind represents one of the most relevant solutions to overcome the increase of the electricity demand challenge. In the recent years, wind energy is gaining more importance among the researchers worldwide. Wind energy is intermittent in nature and hence the power system scheduling and dynamic control of wind turbine requires an estimate of wind energy. Accurate forecast of wind speed is a challenging task for the wind energy research field. In fact, due to the large variability of wind speed caused by the unpredictable and dynamic nature of the earth's atmosphere, there are many fluctuations in wind power production. This inherent variability of wind speed is the main cause of the uncertainty observed in wind power generation. Furthermore, producing wind power forecasts might be obtained indirectly by modeling the wind speed series and then transforming the forecasts through a power curve. Wind speed forecasting techniques have received substantial attention recently and several models have been developed. Basically two main approaches have been proposed in the literature: (1) physical models such as Numerical Weather Forecast and (2) statistical models such as Autoregressive integrated moving average (ARIMA) models, Neural Networks. While the initial focus in the literature has been on point forecasts, the need to quantify forecast uncertainty and communicate the risk of extreme ramp events has led to an interest in producing probabilistic forecasts. In short term

  9. Rainband Feature Tracking for Wind Speeds around Typhoon Eye Using Multiple Sensors

    Science.gov (United States)

    He, S.; Liu, A. A. K.; Yu, C. K.; He, Z.; Yang, J.; Zheng, G.; Chen, Y.

    2016-02-01

    No direct measurements of surface winds are available now except that by aircraft at a high cost, thus tracking and monitoring ocean features which have short coherent time periods from sequential satellite images is a good option to estimate extreme wind speeds associated with typhoons. In this study, five typhoon cases observed by quasi-concurrent satellite-based Synthetic Aperture Radar (SAR) and Moderate Resolution Imaging Spectroradiometer (MODIS) data, and one of the cases also by ground-based Doppler radar observations have been studied. The rainband features around typhoon eyes are first delineated using wavelet analysis, and then the wind speeds are estimated by feature tracking using quasi-concurrent multi-sensor images. The resulting wind speeds are reasonable compared with the maximum wind speed reported from the Joint Typhoon Warning Center (JTWC). In a special case, with the aid of the Doppler radar near the coast, the wind speed estimates based on the multi-sensor also show consistent results. Therefore, it has been demonstrated that a reasonable wind speed around typhoon eyes can be derived from the rainband feature tracking using quasi-concurrent multi-sensor images. This technique may offer useful wind information for typhoon simulations and forecasts.

  10. Installation position determination of wind speed sensors on steel pole along a high-speed railway

    Institute of Scientific and Technical Information of China (English)

    熊小慧; 梁习锋

    2016-01-01

    In order to consider the influence of steel pole on the measurement of wind speed sensors and determinate the installation position of wind speed sensors, the flow field around wind speed sensors was investigated. Based on the three-dimensional steady Reynolds-averaged Navier-Stokes equations andk-ε double equations turbulent model, the field flow around the wind speed sensor and the steel pole along a high-speed railway was simulated on an unstructured grid. The grid-independent validation was conducted and the accuracy of the present numerical simulation method was validated by experiments and simulations carried out by previous researchers. Results show that the steel pole has a significant influence on the measurement results of wind speed sensors. As the distance between two wind speed sensors is varied from 0.3 to 1.0 m, the impact angles are less than ±20°, it is proposed that the distance between two wind speed sensors is 0.8 m at least, and the interval between wind speed sensors and the steel pole is more than 1.0 m with the sensors located on the upstream side.

  11. A Qualitative Description of Boundary Layer Wind Speed Records

    CERN Document Server

    Kavasseri, R G; Nagarajan, Radhakrishnan

    2006-01-01

    The complexity of the atmosphere endows it with the property of turbulence by virtue of which, wind speed variations in the atmospheric boundary layer (ABL) exhibit highly irregular fluctuations that persist over a wide range of temporal and spatial scales. Despite the large and significant body of work on microscale turbulence, understanding the statistics of atmospheric wind speed variations has proved to be elusive and challenging. Knowledge about the nature of wind speed at ABL has far reaching impact on several fields of research such as meteorology, hydrology, agriculture, pollutant dispersion, and more importantly wind energy generation. In the present study, temporal wind speed records from twenty eight stations distributed through out the state of North Dakota (ND, USA), ($\\sim$ 70,000 square-miles) and spanning a period of nearly eight years are analyzed. We show that these records exhibit a characteristic broad multifractal spectrum irrespective of the geographical location and topography. The rapi...

  12. Transient stability of a fixed speed wind farm

    Energy Technology Data Exchange (ETDEWEB)

    Ledesma, P.; Usaola, J.; Rodriguez, J.L. [Universidad Carlos III de Madrid, Madrid (Spain)

    2003-07-01

    A typical fixed speed wind farm connected to a simple grid is modelled. Using this model, a three-phase fault is applied close to the wind farm, and cleared by disconnecting the affected line. The effect of several electric, mechanical and operational parameters on the critical fault-clearing time of this base case is evaluated and discussed. The studied parameters are the short-circuit power at the connection bus, the reactive power compensation, the distance to the fault, the rotor inertia, the hub-generator resonant frequency, the wind speed and the power output. For each parameter, the relationship between its value and the critical fault-clearing time is shown graphically. The results help to understand the transient stability phenomena in fixed speed wind farms, and could help to design fixed speed wind farms attending to transient stability requirements. (Author)

  13. Wind speed and direction measurements using the sphere anemometer

    Science.gov (United States)

    Heisselmann, Hendrik; Hoelling, Michael; Peinke, Joachim

    2009-11-01

    In times of growing energy demand, the importance of wind energy is rapidly increasing and so is the need for accurate wind speed and direction measurements. The widely spread cup anemometers show significant over-speeding under turbulent wind conditions as inherent in atmospherical flows while being solely capable of detecting the wind speed. Therefore, we propose the newly developed sphere anemometer as a simple an robust sensor for direction and velocity measurements. The sphere anemometer exploits the velocity-dependent deflection of a tube, which is the order of μm and can be detected by means of a light pointer as used in atomic force microscopes. In comparative measurements under laboratory conditions the sphere anemometer showed a significantly higher temporal resolution then cup anemometers while it does not exhibit any over-speeding. Additionally, results of atmospherical wind measurements with the sphere anemometer and state-of-the-art cup anemometry are presented.

  14. A nonlinear dynamics approach for incorporating wind-speed patterns into wind-power project evaluation.

    Directory of Open Access Journals (Sweden)

    Ray Huffaker

    Full Text Available Wind-energy production may be expanded beyond regions with high-average wind speeds (such as the Midwest U.S.A. to sites with lower-average speeds (such as the Southeast U.S.A. by locating favorable regional matches between natural wind-speed and energy-demand patterns. A critical component of wind-power evaluation is to incorporate wind-speed dynamics reflecting documented diurnal and seasonal behavioral patterns. Conventional probabilistic approaches remove patterns from wind-speed data. These patterns must be restored synthetically before they can be matched with energy-demand patterns. How to accurately restore wind-speed patterns is a vexing problem spurring an expanding line of papers. We propose a paradigm shift in wind power evaluation that employs signal-detection and nonlinear-dynamics techniques to empirically diagnose whether synthetic pattern restoration can be avoided altogether. If the complex behavior of observed wind-speed records is due to nonlinear, low-dimensional, and deterministic system dynamics, then nonlinear dynamics techniques can reconstruct wind-speed dynamics from observed wind-speed data without recourse to conventional probabilistic approaches. In the first study of its kind, we test a nonlinear dynamics approach in an application to Sugarland Wind-the first utility-scale wind project proposed in Florida, USA. We find empirical evidence of a low-dimensional and nonlinear wind-speed attractor characterized by strong temporal patterns that match up well with regular daily and seasonal electricity demand patterns.

  15. 输电线路超声波自校正风速风向监测系统的设计%Ultrasonic Wind Speed and Dircetion Monitor System of Transmission Line

    Institute of Scientific and Technical Information of China (English)

    李佳奇; 刘松; 赵义松

    2015-01-01

    针对传统输电线路机械式风速风向采集系统的不足,设计了一种以ARM为核心的风速风向采集仪。该系统采用STM32处理器,以超声波时差法为测试手段,同时采用温度补偿技术,地磁角校正技术以及GPS定位技术,实现了输电线路风速风向的准确监测,并通过GPRS实时发送数据至主控室。该系统具有免维护、功耗低、精度高、安装方便等优点,可广泛用在输电线路监测环境中。%To overcome shortcomings of traditional mechanical anemometer wind acquisition system of power transmission line , the ARM wind collect instrument was designed.The system used STM32as processor,ultrasonic-time-difference testing method and temperature compensation technology,geomagnetic angle correcting and GPS positioning technology realizing accurate test of wind speed and wind direction of transmission line,and the collected data can be realt-ime transmitted to the main control room.The sys-tem is free-maintenance, and has low power consumption,high precision,and convenient installation,which can be widely used in power transmission line monitoring environment.

  16. Interval forecasts of a novelty hybrid model for wind speeds

    Directory of Open Access Journals (Sweden)

    Shanshan Qin

    2015-11-01

    Full Text Available The utilization of wind energy, as a booming technology in the field of renewable energies, has been highly regarded around the world. Quantification of uncertainties associated with accurate wind speed forecasts is essential for regulating wind power generation and integration. However, it remains difficult work primarily due to the stochastic and nonlinear characteristics of wind speed series. Traditional models for wind speed forecasting mostly focus on generating certain predictive values, which cannot properly handle uncertainties. For quantifying potential uncertainties, a hybrid model constructed by the Cuckoo Search Optimization (CSO-based Back Propagation Neural Network (BPNN is proposed to establish wind speed interval forecasts (IFs by estimating the lower and upper bounds. The quality of IFs is assessed quantitatively using IFs coverage probability (IFCP and IFs normalized average width (IFNAW. Moreover, to assess the overall quality of IFs comprehensively, a tradeoff between informativeness (IFNAW and validity (IFCP of IFs is examined by coverage width-based criteria (CWC. As an applicative study, wind speeds from the Xinjiang Region in China are used to validate the proposed hybrid model. The results demonstrate that the proposed model can construct higher quality IFs for short-term wind speed forecasts.

  17. Verification of high-speed solar wind stream forecasts using operational solar wind models

    OpenAIRE

    Reiss, Martin A.; Temmer, Manuela; Veronig, Astrid M.; Nikolic, Ljubomir; Vennerstrom, Susanne; Schoengassner, Florian; Hofmeister, Stefan J.

    2016-01-01

    High-speed solar wind streams emanating from coronal holes are frequently impinging on the Earth's magnetosphere causing recurrent, medium-level geomagnetic storm activity. Modeling high-speed solar wind streams is thus an essential element of successful space weather forecasting. Here we evaluate high-speed stream forecasts made by the empirical solar wind forecast (ESWF) and the semiempirical Wang-Sheeley-Arge (WSA) model based on the in situ plasma measurements from the ACE spacecraft for ...

  18. Representivity of wind measurements for design wind speed estimations

    CSIR Research Space (South Africa)

    Goliger, Adam M

    2013-07-01

    Full Text Available of instrumentation sited according to World Meteorological Organization (WMO) requirements. With the advent of automatic weather station technology several decades ago, wind measurements have become much more cost-effective. While previously wind measurements were...

  19. Indirect sensorless speed control of a PMSG for wind application

    DEFF Research Database (Denmark)

    Diaz, S.A.; Silva, C.; Juliet, J.

    2009-01-01

    the method usually referred in the literature as indirect speed control (ISC). The principle of this method is the regulation of the generator torque as function of rotor speed such that the steady state operation is at the MPPT. This strategy normally requires the knowledge of the shaft speed to determinate...... in the whole wind generator system a sensorless scheme is proposed, thereby avoiding problems of electromagnetic interferences and failures in the position sensor. Usually, in wind drive system, the generator is not operated a very low speeds, therefore problems related to low back-emf for flux estimation...... by a squirrel cage induction machine used as wind turbine emulator and the permanent magnet generator. A control program uses a simulated wind profile and gives the speed reference for the induction machine drive, considering the turbine torque production and the inertia of the system. Experimental results...

  20. Effects of surface wind speed decline on hydrology in China

    Science.gov (United States)

    Liu, X.; Zhang, X.; Tang, Q.; Zhang, X.

    2013-12-01

    Surface wind speed decline in China has been widely reported, but its effects on hydrology have not been fully evaluated to date. In this study, we evaluate the effects of wind speed decline on hydrology in China during 1966-2011 by using the Variable Infiltration Capacity (VIC) hydrological model. Two model experiments, i.e. VIC simulations with the observed (EXP1) and detrended wind speed (EXP2), are performed in the major river basins in China. The differences between the two experiments are analyzed to assess the effects of wind speed decline on hydrology. Results show that wind speed has decreased by 29% of its mean in China, even by 80% for some areas in the northern China. The wind speed decline have resulted in a decrease of evapotranspiration by 1-3% of mean annual evapotranspiration and an increase of runoff by 1-6% of mean annual runoff at most basins in China. The effect of wind speed on runoff and soil moisture is large in the northern basins where small change in hydrological conditions would have significant implications for water management. In addition, Wind speed decline has offset the expansion of the drought area in China. It has contributed to a reduction of drought areas by 21%, 17%, 15% and 12% for the mean drought area in the Songhuajiang River, Hai River, Liao River and Yellow River basins, respectively, and by 8.8% of the mean drought area over China. The effect of wind speed decline on soil moisture drought is large in most basins in China expect for the Southwest and Pearl River basins.

  1. Wind speed dynamical model in a wind farm

    DEFF Research Database (Denmark)

    Soleimanzadeh, Maryam; Wisniewski, Rafal

    2010-01-01

    , the dynamic model for wind flow will be established. The state space variables are determined based on a fine mesh defined for the farm. The end goal of this method is to assist the development of a dynamical model of a wind farm that can be engaged for better wind farm control strategies....

  2. Improving the Accuracy of Wind Turbine Power Curve Validation by the Rotor Equivalent Wind Speed Concept

    Science.gov (United States)

    Scheurich, Frank; Enevoldsen, Peder B.; Paulsen, Henrik N.; Dickow, Kristoffer K.; Fiedel, Moritz; Loeven, Alex; Antoniou, Ioannis

    2016-09-01

    The measurement of the wind speed at hub height is part of the current IEC standard procedure for the power curve validation of wind turbines. The inherent assumption is thereby made that this measured hub height wind speed sufficiently represents the wind speed across the entire rotor area. It is very questionable, however, whether the hub height wind speed (HHWS) method is appropriate for rotor sizes of commercial state-of-the-art wind turbines. The rotor equivalent wind speed (REWS) concept, in which the wind velocities are measured at several different heights across the rotor area, is deemed to be better suited to represent the wind speed in power curve measurements and thus results in more accurate predictions of the annual energy production (AEP) of the turbine. The present paper compares the estimated AEP, based on HHWS power curves, of two different commercial wind turbines to the AEP that is based on REWS power curves. The REWS was determined by LiDAR measurements of the wind velocities at ten different heights across the rotor area. It is shown that a REWS power curve can, depending on the wind shear profile, result in higher, equal or lower AEP estimations compared to the AEP predicted by a HHWS power curve.

  3. Correlation of mesoscale wind speeds over the sea

    DEFF Research Database (Denmark)

    Mehrens, Anna R.; Hahmann, Andrea N.; Larsén, Xiaoli Guo

    2016-01-01

    . The correlation coefficient as a function of the distance calculated from WRF is however higher than observed in the measurements. For the power spectra, wind speed and wind speed step changes distribution the results for all sites are quite similar. The land masses strongly influence the individual wind......A large offshore observational data set from stations across the North and Baltic Sea is used to investigate the planetary boundary layer wind characteristics and their coherence, correlation and power spectra. The data of thirteen sites, with pairs of sites at a horizontal distance of 4 to 848 km......, are analyzed for typical wind turbine nacelle heights. Mean wind characteristics, correlation and coherence are also calculated for analogous wind data from simulations with the Weather Research and Forecasting (WRF) model. Results indicate a general good agreement for the coherence calculated based...

  4. Contribution of variable-speed wind turbines to voltage control

    Energy Technology Data Exchange (ETDEWEB)

    Ledesma, P.; Usaola, J.

    2003-07-01

    Variable speed, grid connected, wind turbines open new possibilities for voltage control, because they use electronic converters, which may regulate the reactive power interchange with the grid. This paper proposes two voltage control schemes for variable speed wind turbines with double-fed induction generator. The first scheme acts on the wind-turbine power factor, while the latter acts directly on the converter current. Advantages and draw backs of both techniques are discussed. Both control techniques have been tested by simulations of a base case, which represent a synchronous generator, a wind farm and a local load, and several disturbances such as the loss of compensator capacitors. (author)

  5. Effects of Yaw Error on Wind Turbine Running Characteristics Based on the Equivalent Wind Speed Model

    Directory of Open Access Journals (Sweden)

    Shuting Wan

    2015-06-01

    Full Text Available Natural wind is stochastic, being characterized by its speed and direction which change randomly and frequently. Because of the certain lag in control systems and the yaw body itself, wind turbines cannot be accurately aligned toward the wind direction when the wind speed and wind direction change frequently. Thus, wind turbines often suffer from a series of engineering issues during operation, including frequent yaw, vibration overruns and downtime. This paper aims to study the effects of yaw error on wind turbine running characteristics at different wind speeds and control stages by establishing a wind turbine model, yaw error model and the equivalent wind speed model that includes the wind shear and tower shadow effects. Formulas for the relevant effect coefficients Tc, Sc and Pc were derived. The simulation results indicate that the effects of the aerodynamic torque, rotor speed and power output due to yaw error at different running stages are different and that the effect rules for each coefficient are not identical when the yaw error varies. These results may provide theoretical support for optimizing the yaw control strategies for each stage to increase the running stability of wind turbines and the utilization rate of wind energy.

  6. 622 Mbps High-speed satellite communication system for WINDS

    Science.gov (United States)

    Ogawa, Yasuo; Hashimoto, Yukio; Yoshimura, Naoko; Suzuki, Ryutaro; Gedney, Richard T.; Dollard, Mike

    2006-07-01

    WINDS is the experimental communications satellite currently under joint development by Japanese Aerospace Exploration Agency (JAXA) and the National Institute of Information and Communications Technology (NICT). The high-speed satellite communication system is very effective for quick deployment of high-speed networks economically. The WINDS will realize ultra high-speed networking and demonstrate operability of satellite communication systems in high-speed internet. NICT is now developing high-speed satellite communication system for WINDS. High-speed TDMA burst modem with high performance TPC error correction is underdevelopment. Up to the DAC on the transmitter and from the ADC on the receiver, all modem functions are performed in the digital processing technology. Burst modem has been designed for a user data rate up to 1244 Mbps. NICT is developing the digital terminal as a user interface and a network controller for this earth station. High compatibility with the Internet will be provided.

  7. Algorithm for wind speed estimate with polarimetric radar

    Directory of Open Access Journals (Sweden)

    Ю. А. Авер’янова

    2013-07-01

    Full Text Available The connection of wind speed and drops behavior is substantiated as well as the drop behavior influence onto the polarization characteristics of electromagnetic waves. The expression to calculate the wind speed taking into account the Weber number for the critical regime of drop deformation is obtained. The critical regime of drop deformation is the regime when drop is divided into two parts. The dependency of critical wind speed on the drop diameter is calculated and shown. The concept o polarization spectrum that is introduced in the previous papers is used to estimate the dynamic processes in the atmosphere. At the moment when the drop is under the influence of the wind that is equal to the critical wind speed the drop will be divided into two parts. This process will be reflected as the appearance of the two equal components of polarization spectra of reflected electromagnetic waves at the orthogonal antennas of Doppler Polarimetric Radar. Owing the information about the correspondence of the polarization component energy level to the drop diameter it is possible to estimate the wind speed with the obtained dependency. The process of the wind speed estimate with polarimetric radar is presented with the developed common algorithm

  8. Acoustic emission monitoring of wind turbine blades

    Science.gov (United States)

    Van Dam, Jeremy; Bond, Leonard J.

    2015-03-01

    Damage to wind turbine blades can, if left uncorrected, evolve into catastrophic failures resulting in high costs and significant losses for the operator. Detection of damage, especially in real time, has the potential to mitigate the losses associated with such catastrophic failure. To address this need various forms of online monitoring are being investigated, including acoustic emission detection. In this paper, pencil lead breaks are used as a standard reference source and tests are performed on unidirectional glass-fiber-reinforced-polymer plates. The mechanical pencil break is used to simulate an acoustic emission (AE) that generates elastic waves in the plate. Piezoelectric sensors and a data acquisition system are used to detect and record the signals. The expected dispersion curves generated for Lamb waves in plates are calculated, and the Gabor wavelet transform is used to provide dispersion curves based on experimental data. AE sources using an aluminum plate are used as a reference case for the experimental system and data processing validation. The analysis of the composite material provides information concerning the wave speed, modes, and attenuation of the waveform, which can be used to estimate maximum AE event - receiver separation, in a particular geometry and materials combination. The foundational data provided in this paper help to guide improvements in online structural health monitoring of wind turbine blades using acoustic emission.

  9. Roundfish monitoring Princess amalia Wind Farm

    NARCIS (Netherlands)

    Hal, van R.

    2013-01-01

    This report describes the results of field work in the Princess Amalia Wind Farm (in Dutch: Prinses Amaliawindpark, or PAWP). It is to realize the requirements of the Monitoring and Evaluation Program, which is part of the Wbr-permit of the wind farm. The objective is to determine if the wind farm f

  10. Wind Turbine Drivetrain Condition Monitoring - An Overview

    Energy Technology Data Exchange (ETDEWEB)

    Sheng, S; Veers, P.

    2011-10-01

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

  11. Design of Wind Turbine Vibration Monitoring System

    Directory of Open Access Journals (Sweden)

    Shoubin Wang

    2013-04-01

    Full Text Available In order to ensure safety of wind turbine operation and to reduce the occurrence of faults as well as to improve the reliability of wind turbine operation, a vibration monitoring for wind turbine is developed. In this paper, it analyses the enlargement of all the parts of the structure and the working mechanism, the research method of wind turbine operation vibration is introduced, with the focus being the use of the sensor principle. Finally the hardware design and software of this system is introduced and the main function of this system is described, which realizes condition monitoring of the work state of wind turbines.

  12. The Probability Distribution Model of Wind Speed over East Malaysia

    Directory of Open Access Journals (Sweden)

    Nurulkamal Masseran

    2013-07-01

    Full Text Available Many studies have found that wind speed is the most significant parameter of wind power. Thus, an accurate determination of the probability distribution of wind speed is an important parameter to measure before estimating the wind energy potential over a particular region. Utilizing an accurate distribution will minimize the uncertainty in wind resource estimates and improve the site assessment phase of planning. In general, different regions have different wind regimes. Hence, it is reasonable that different wind distributions will be found for different regions. Because it is reasonable to consider that wind regimes vary according to the region of a particular country, nine different statistical distributions have been fitted to the mean hourly wind speed data from 20 wind stations in East Malaysia, for the period from 2000 to 2009. The values from Kolmogorov-Smirnov statistic, Akaike’s Information Criteria, Bayesian Information Criteria and R2 correlation coefficient were compared with the distributions to determine the best fit for describing the observed data. A good fit for most of the stations in East Malaysia was found using the Gamma and Burr distributions, though there was no clear pattern observed for all regions in East Malaysia. However, the Gamma distribution was a clear fit to the data from all stations in southern Sabah.

  13. VT Predicted Mean Wind Speed - 30 meter height

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) Wind speed predictions at 30m are generated by a numerical model that simulates weather conditions over a 15-year period, taking into account...

  14. VT Predicted Mean Wind Speed - 70 meter height

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) Wind speed predictions at 70m are generated by a numerical model that simulates weather conditions over a 15-year period, taking into account...

  15. Hurricane Imaging Radiometer (HIRAD) Wind Speed Retrieval Assessment with Dropsondes

    Science.gov (United States)

    Cecil, Daniel J.; Biswas, Sayak K.

    2017-01-01

    Map surface wind speed over wide swath (approximately 50-60 km, for aircraft greater than FL600) in hurricanes. Provide research data for understanding hurricane structure, and intensity change. Enable improved forecasts, warnings, and decision support.

  16. Estimation of wind speed and wave height during cyclones

    Digital Repository Service at National Institute of Oceanography (India)

    SanilKumar, V.; Mandal, S.; AshokKumar, K.

    reported by ships were comparable. Empirical expressions relating wind speed, wave height and wave period to storm parameters were derived. The design wave height for different return periods was obtained by fitting a two-parameter Weibull distribution...

  17. Decomposition of wind speed fluctuations at different time scales

    Indian Academy of Sciences (India)

    Qinmin Zheng; S Rehman; Md Mahbub Alam; L M Alhems; A Lashin

    2017-04-01

    Understanding the inherent features of wind speed (variability on different time scales) has become critical for assured wind power availability, grid stability, and effective power management. The study utilizes the wavelet, autocorrelation, and FFT (fast Fourier transform) techniques to analyze and assimilate the fluctuating nature of wind speed data collected over a period of 29–42 years at different locations in the Kingdom of Saudi Arabia. The analyses extracted the intrinsic features of wind speed, including the long-term mean wind speed and fluctuations at different time scales (periods), which is critical for meteorological purposes including wind power resource assessment and weather forecasting. The longterm mean wind speed varied between 1.45 m/s at Mecca station and 3.73 m/s at Taif. The annual variation is the largest (±0.97 m/s) at Taif and the smallest (±0.25 m/s) at Mecca. Similarly, the wind speed fluctuation with different periods was also discussed in detail. The spectral characteristics obtained using FFT reveal that Al-Baha, Najran, Taif and Wadi-Al-Dawasser having a sharp peak at a frequency f = 0.00269 (1/day) retain a more regular annual repetition of wind speed than Bisha, Khamis-Mushait, Madinah, Mecca, and Sharourah. Based on the autocorrelation analysis and FFT results, the stations are divided into three groups: (i) having strong annual modulations (Al-Baha, Najran, Taif and Wadi-Al-Dawasser), (ii) having comparable annual and half-yearly modulations (Bisha, Khamis-Mushait, and Mecca) and (iii) having annual modulation moderately prominent (Madinah and Sharourah).

  18. Correlation of mesoscale wind speeds over the sea

    DEFF Research Database (Denmark)

    Mehrens, Anna R.; Hahmann, Andrea N.; Larsén, Xiaoli Guo

    2016-01-01

    , are analyzed for typical wind turbine nacelle heights. Mean wind characteristics, correlation and coherence are also calculated for analogous wind data from simulations with the Weather Research and Forecasting (WRF) model. Results indicate a general good agreement for the coherence calculated based....... The correlation coefficient as a function of the distance calculated from WRF is however higher than observed in the measurements. For the power spectra, wind speed and wind speed step changes distribution the results for all sites are quite similar. The land masses strongly influence the individual wind...... direction distribution of each site. The ability of the WRF model to reproduce the coherence of the measurements demonstrates that its output can be used to estimate the coherence of fluctuations for the integration of offshore energy. The power spectra of WRF time series underestimates the high frequency...

  19. Verification of high-speed solar wind stream forecasts using operational solar wind models

    Science.gov (United States)

    Reiss, Martin A.; Temmer, Manuela; Veronig, Astrid M.; Nikolic, Ljubomir; Vennerstrom, Susanne; Schöngassner, Florian; Hofmeister, Stefan J.

    2016-07-01

    High-speed solar wind streams emanating from coronal holes are frequently impinging on the Earth's magnetosphere causing recurrent, medium-level geomagnetic storm activity. Modeling high-speed solar wind streams is thus an essential element of successful space weather forecasting. Here we evaluate high-speed stream forecasts made by the empirical solar wind forecast (ESWF) and the semiempirical Wang-Sheeley-Arge (WSA) model based on the in situ plasma measurements from the Advanced Composition Explorer (ACE) spacecraft for the years 2011 to 2014. While the ESWF makes use of an empirical relation between the coronal hole area observed in Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) images and solar wind properties at the near-Earth environment, the WSA model establishes a link between properties of the open magnetic field lines extending from the photosphere to the corona and the background solar wind conditions. We found that both solar wind models are capable of predicting the large-scale features of the observed solar wind speed (root-mean-square error, RMSE ≈100 km/s) but tend to either overestimate (ESWF) or underestimate (WSA) the number of high-speed solar wind streams (threat score, TS ≈ 0.37). The predicted high-speed streams show typical uncertainties in the arrival time of about 1 day and uncertainties in the speed of about 100 km/s. General advantages and disadvantages of the investigated solar wind models are diagnosed and outlined.

  20. Pitch Based Wind Turbine Intelligent Speed Setpoint Adjustment Algorithms

    Directory of Open Access Journals (Sweden)

    Asier González-González

    2014-06-01

    Full Text Available This work is aimed at optimizing the wind turbine rotor speed setpoint algorithm. Several intelligent adjustment strategies have been investigated in order to improve a reward function that takes into account the power captured from the wind and the turbine speed error. After different approaches including Reinforcement Learning, the best results were obtained using a Particle Swarm Optimization (PSO-based wind turbine speed setpoint algorithm. A reward improvement of up to 10.67% has been achieved using PSO compared to a constant approach and 0.48% compared to a conventional approach. We conclude that the pitch angle is the most adequate input variable for the turbine speed setpoint algorithm compared to others such as rotor speed, or rotor angular acceleration.

  1. Wind speed power spectrum analysis for Bushland, Texas

    Energy Technology Data Exchange (ETDEWEB)

    Eggleston, E.D. [USDA-Agricultural Research Service, Bushland, TX (United States)

    1996-12-31

    Numerous papers and publications on wind turbulence have referenced the wind speed spectrum presented by Isaac Van der Hoven in his article entitled Power Spectrum of Horizontal Wind Speed Spectrum in the Frequency Range from 0.0007 to 900 Cycles per Hour. Van der Hoven used data measured at different heights between 91 and 125 meters above the ground, and represented the high frequency end of the spectrum with data from the peak hour of hurricane Connie. These facts suggest we should question the use of his power spectrum in the wind industry. During the USDA - Agricultural Research Service`s investigation of wind/diesel system power storage, using the appropriate wind speed power spectrum became a significant issue. We developed a power spectrum from 13 years of hourly average data, 1 year of 5 minute average data, and 2 particularly gusty day`s 1 second average data all collected at a height of 10 meters. While the general shape is similar to the Van der Hoven spectrum, few of his peaks were found in the Bushland spectrum. While higher average wind speeds tend to suggest higher amplitudes in the high frequency end of the spectrum, this is not always true. Also, the high frequency end of the spectrum is not accurately described by simple wind statistics such as standard deviation and turbulence intensity. 2 refs., 5 figs., 1 tab.

  2. Rotor equivalent wind speed for power curve measurement – comparative exercise for IEA Wind Annex 32

    DEFF Research Database (Denmark)

    Wagner, Rozenn; Cañadillas, B.; Clifton, A.;

    2014-01-01

    was the definition of the segment area used as weighting for the wind speeds measured at the various heights in the calculation of the REWS. This comparative exercise showed that the REWS method results in a significant difference compared to the standard method using the wind speed at hub height in conditions...

  3. Prediction of wind power potential by wind speed probability distribution in a hilly terrain near Bh

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Siraj; Diwakar, Nilesh

    2010-09-15

    Daily wind speed data in metre per second and its direction of flow in degree were recorded from of the India Meteorological Department for a site near the Bhopal Airport for the period of eleven years. The influence of roughness of the terrain, obstacles and topography in terms of contour for the area were also taken into consideration. These data were analysed using WAsP programme and regional wind climate of the area was determined. It is seen from the analysis of the wind speed data and keeping the topographical variation of terrain, exploitable wind speed is experienced at 50 m.

  4. Offshore wind speed and wind power characteristics for ten locations in Aegean and Ionian Seas

    Indian Academy of Sciences (India)

    Haralambos S Bagiorgas; Giouli Mihalakakou; Shafiqur Rehman; Luai M Al-Hadhrami

    2012-08-01

    This paper utilizes wind speed data measured at 3 and 10 m above water surface level using buoys at 10 stations in Ionian and Aegean Seas to understand the behaviour of wind and thereafter energy yield at these stations using 5 MW rated power offshore wind turbine. With wind power densities of 971 and 693 W/m2 at 50 m above water surface level, Mykonos and Lesvos were found to be superb and outstanding windy sites with wind class of 7 and 6, respectively. Other locations like Athos, Santorini and Skyros with wind power density of more than 530 W/m2 and wind class of 5 were found to be the excellent sites. Around 15–16% higher winds were observed at 10 m compared to that at 3 m. Lower values of wind speed were found during summer months and higher during winter time in most of the cases reported in the present work. Slightly decreasing (∼2% per year) linear trends were observed in annual mean wind speed at Lesvos and Santorini. These trends need to be verified with more data from buoys or from nearby onshore meteorological stations. At Athos and Mykonos, increasing linear trends were estimated. At all the stations the chosen wind turbine could produce energy for more than 70% of the time. The wind speed distribution was found to be well represented by Weibull parameters obtained using Maximum likelihood method compared to WAsP and Method of Moments.

  5. Wind shear proportional errors in the horizontal wind speed sensed by focused, range gated lidars

    DEFF Research Database (Denmark)

    Lindelöw, Per Jonas Petter; Courtney, Michael; Parmentier, R.

    2008-01-01

    The 10-minute average horizontal wind speeds sensed with lidar and mast mounted cup anemometers, at 60 to 116 meters altitude at Hovsore, are compared. The lidar deviation from the cup value as a function of wind velocity and wind shear is studied in a 2-parametric regression analysis which revea...

  6. Climate projection of extreme wind speed regime in the Arctic

    Science.gov (United States)

    Surkova, Galina; Sokolova, Larisa

    2016-04-01

    Extreme surface wind events over the Arctic (60-90N, 0-360 E) are studied for the modern climate and for its future possible changes on the base of ERA-Interim reanalysis data and CMIP5 scenario RCP8.5. Horizontal surface wind speed (10 m) probability distribution functions in every grid point of reanalysis and models data over the Arctic were evaluated as well as wind speed for 50, 95, 99, 99.9 percentiles (V0.50, V0.95, V0.99, V0.999). At first, changes of V0.50, V0.95, V0.99, V0.999 were studied on the base of ERA-Interim reanalysis for 1981-2010. Results showed regional inhomogenity of wind speed trend intensity. Also, analysis was made for zonal means and separate sectors of the Arctic. To study climate projection of high wind speed there were taken u,v values from CMIP5 numerical experiments for 1961-1990 (Historical) and 2081-2100 (RCP8.5). RCP8.5 scenario was chosen as having the most pronounced response in the climate system, which gave more statistical significance to the calculated trends. Modeled extreme wind speeds for the total Arctic and zonal means show rather good agreement with reanalysis data (compared for decades 1981-1990, 1991-2000). At the same time regional intermodel variability of wind speed is revealed. Trend of extreme surface wind speed in 21 century and for 2081-2100 over the Arctic are analyzed for each model. The study was supported by the Russian Science Foundation (project no. 14-37-00038).

  7. Thermal loading of wind power converter considering dynamics of wind speed

    DEFF Research Database (Denmark)

    Baygildina, Elvira; Peltoniemi, Pasi; Pyrhönen, Olli;

    2013-01-01

    The thermal loading of power semiconductors is a crucial performance related to the reliability and cost of the wind power converter. However, the thermal loading impacts by the variation of wind speeds have not yet been clarified, especially when considering the aerodynamic behavior of the wind...... turbines. In this paper, the junction temperatures in the wind power converter are studied under not only steady state, but also turbulent wind speed conditions. The study is based on a 1.5 MW direct-driven turbine system with aerodynamic model described by Unsteady Blade Element Momentum Method (BEMM......), and the thermal stress of power devices is investigated from the frequency spectrum point of view of wind speed. It is concluded that because of the strong inertia effects by the aerodynamic behavior of wind turbines, thermal stress of the semiconductors is relatively more stable and only influenced by the low...

  8. Hurricane Wind Speed Estimation Using WindSat 6 and 10 GHz Brightness Temperatures

    Directory of Open Access Journals (Sweden)

    Lei Zhang

    2016-08-01

    Full Text Available The realistic and accurate estimation of hurricane intensity is highly desired in many scientific and operational applications. With the advance of passive microwave polarimetry, an alternative opportunity for retrieving wind speed in hurricanes has become available. A wind speed retrieval algorithm for wind speeds above 20 m/s in hurricanes has been developed by using the 6.8 and 10.7 GHz vertically and horizontally polarized brightness temperatures of WindSat. The WindSat measurements for 15 category 4 and category 5 hurricanes from 2003 to 2010 and the corresponding H*wind analysis data are used to develop and validate the retrieval model. In addition, the retrieved wind speeds are also compared to the Remote Sensing Systems (RSS global all-weather product and stepped-frequency microwave radiometer (SFMR measurements. The statistical results show that the mean bias and the overall root-mean-square (RMS difference of the retrieved wind speeds with respect to the H*wind analysis data are 0.04 and 2.75 m/s, respectively, which provides an encouraging result for retrieving hurricane wind speeds over the ocean surface. The retrieved wind speeds show good agreement with the SFMR measurements. Two case studies demonstrate that the mean bias and RMS difference are 0.79 m/s and 1.79 m/s for hurricane Rita-1 and 0.63 m/s and 2.38 m/s for hurricane Rita-2, respectively. In general, the wind speed retrieval accuracy of the new model in hurricanes ranges from 2.0 m/s in light rain to 3.9 m/s in heavy rain.

  9. Comparison of NWP wind speeds and directions to measured wind speeds and directions

    Energy Technology Data Exchange (ETDEWEB)

    Astrup, P.; Mikkelsen, Torben

    2010-09-15

    Numerical Weather Predictions (NWP) of wind speed and direction has been compared to measurements for seven German sites for nuclear power plants, and for Risoe, the site of the Danish nuclear research reactors now being decommissioned . For the German sites the data cover approximately three month, the NWP data from Austrian Meteorological and Geophysical Office, AMGO, cover 5th January to 31st March 2009 with two daily sets of analysis and 1 to 48 hours forecasts, the measured data cover the full three month, i.e. from 1st January, with 10 minute resolution. For the Risoe site NWP results of the HIRLAM code from Danish Meteorological Institute were once stored for two thirds of a year, i.e. 1017 times analysis and 1 to 5 hour forecast within the period 21st October 1998 to 30th September 1999, and 10 minute averaged measured data are available since November 1995. (author)

  10. The Radial Evolution of Solar Wind Speeds (Postprint)

    Science.gov (United States)

    2012-03-05

    the equatorial region, solar wind observed above 600 km/s has rarely been accelerated from slower speeds (see Figure 3), therefore speeds greater...unlimited. ratios. This solar wind rarely has an O7+/O6+ value greater than 0.05, or a C6+/C5+ charge state ratio greater than 0.5. These maximum O7+/O6...structure and coronal sources of the solar wind during May 12th, 1997 CME, J. Atmos. Sol. Terr . Phys., 66, 1295–1309. Hefti, S., H. Grunwaldt, P

  11. Load flow analysis for variable speed offshore wind farms

    DEFF Research Database (Denmark)

    Chen, Zhe; Zhao, Menghua; Blaabjerg, Frede

    2009-01-01

    A serial AC-DC integrated load flow algorithm for variable speed offshore wind farms is proposed. It divides the electrical system of a wind farm into several local networks, and different load flow methods are used for these local networks sequentially. This method is fast, more accurate, and many...... and integrated into the load flow algorithm: one takes into account the control strategy of converters and the other considers the power losses of converters. In addition, different types of variable speed wind turbine systems with different control methods are investigated. Finally, the method is demonstrated...

  12. Day-Ahead Wind Speed Forecasting Using Relevance Vector Machine

    Directory of Open Access Journals (Sweden)

    Guoqiang Sun

    2014-01-01

    Full Text Available With the development of wind power technology, the security of the power system, power quality, and stable operation will meet new challenges. So, in this paper, we propose a recently developed machine learning technique, relevance vector machine (RVM, for day-ahead wind speed forecasting. We combine Gaussian kernel function and polynomial kernel function to get mixed kernel for RVM. Then, RVM is compared with back propagation neural network (BP and support vector machine (SVM for wind speed forecasting in four seasons in precision and velocity; the forecast results demonstrate that the proposed method is reasonable and effective.

  13. Power curve report - with rotor equivalent wind speed

    DEFF Research Database (Denmark)

    Villanueva, Héctor; Gómez Arranz, Paula

    This report describes the power curve measurements carried out on a given wind turbine in a chosen period. The measurements were carried out following the measurement procedure in the draft of IEC 61400-12-1 Ed.2 [1], with some deviations mostly regarding uncertainty calculation. Here......, the reference wind speed used in the power curve is the equivalent wind speed obtained from lidar measurements at several heights between lower and upper blade tip, in combination with a hub height meteorological mast. The measurements have been performed using DTU’s measurement equipment, the analysis...

  14. Wind speed forecasting in the South Coast of Oaxaca, Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Cadenas, Erasmo [Facultad de Ingenieria Mecanica, Universidad Michoacana de San Nicolas de Hidalgo, Santiago Tapia No. 403, Centro (Mexico); Rivera, Wilfrido [Centro de Investigacion en Energia of the Universidad Nacional Autonoma de Mexico (UNAM), Apartado Postal 34, Temixco 62580, Morelos (Mexico)

    2007-10-15

    Comparison of two techniques for wind speed forecasting in the South Coast of the state of Oaxaca, Mexico is presented in this paper. The Autoregressive Integrated Moving Average (ARIMA) and the Artificial Neural Networks (ANN) methods are applied to a time series conformed by 7 years of wind speed measurements. Six years were used in the formulation of the models and the last year was used to validate and compare the effectiveness of the generated prediction by the techniques mentioned above. Seasonal ARIMA models present a better sensitivity to the adjustment and prediction of the wind speed for this case in particular. Nevertheless, it was shown both developed models can be used to predict in a reasonable way, the monthly electricity production of the wind power stations in La Venta, Oaxaca, Mexico to support the operators of the Electric Utility Control Centre. (author)

  15. Flicker Mitigation by Speed Control of Permanent Magnet Synchronous Generator Variable-Speed Wind Turbines

    Directory of Open Access Journals (Sweden)

    Yanting Hu

    2013-07-01

    Full Text Available Grid-connected wind turbines are fluctuating power sources that may produce flicker during continuous operation. This paper presents a simulation model of a MW-level variable speed wind turbine with a full-scale back-to-back power converter and permanent magnet synchronous generator (PMSG developed in the simulation tool of PSCAD/EMTDC. Flicker emission of this system is investigated. The 3p (three times per revolution power oscillation due to wind shear and tower shadow effects is the significant part in the flicker emission of variable speed wind turbines with PMSG during continuous operation. A new method of flicker mitigation by controlling the rotational speed is proposed. It smoothes the 3p active power oscillations from wind shear and tower shadow effects of the wind turbine by varying the rotational speed of the PMSG. Simulation results show that damping the 3p active power oscillation by using the flicker mitigation speed controller is an effective means for flicker mitigation of variable speed wind turbines with full-scale back-to-back power converters and PMSG during continuous operation.

  16. Wide Area Wind Field Monitoring Status & Results

    Energy Technology Data Exchange (ETDEWEB)

    Alan Marchant; Jed Simmons

    2011-09-30

    Volume-scanning elastic has been investigated as a means to derive 3D dynamic wind fields for characterization and monitoring of wind energy sites. An eye-safe volume-scanning lidar system was adapted for volume imaging of aerosol concentrations out to a range of 300m. Reformatting of the lidar data as dynamic volume images was successfully demonstrated. A practical method for deriving 3D wind fields from dynamic volume imagery was identified and demonstrated. However, the natural phenomenology was found to provide insufficient aerosol features for reliable wind sensing. The results of this study may be applicable to wind field measurement using injected aerosol tracers.

  17. A Diagnostic Diagram to Understand the Marine Atmospheric Boundary Layer at High Wind Speeds

    Science.gov (United States)

    Kettle, Anthony

    2014-05-01

    Long time series of offshore meteorological measurements in the lower marine atmospheric boundary layer show dynamical regimes and variability that are forced partly by interaction with the underlying sea surface and partly by the passage of cloud systems overhead. At low wind speeds, the dynamics and stability structure of the surface layer depend mainly on the air-sea temperature difference and the measured wind speed at a standard height. The physical processes are mostly understood and the quantified through Monin-Obukhov (MO) similarity theory. At high wind speeds different dynamical regimes become dominant. Breaking waves contribute to the atmospheric loading of sea spray and water vapor and modify the character of air-sea interaction. Downdrafts and boundary layer rolls associated with clouds at the top of the boundary layer impact vertical heat and momentum fluxes. Data from offshore meteorological monitoring sites will typically show different behavior and the regime shifts depending on the local winds and synoptic conditions. However, the regular methods to interpret time series through spectral analysis give only a partial view of dynamics in the atmospheric boundary layer. Also, the spectral methods have limited use for boundary layer and mesoscale modellers whose geophysical diagnostics are mostly anchored in directly measurable quantities: wind speed, temperature, precipitation, pressure, and radiation. Of these, wind speed and the air-sea temperature difference are the most important factors that characterize the dynamics of the lower atmospheric boundary layer and they provide a dynamical and thermodynamic constraint to frame observed processes, especially at high wind speeds. This was recognized in the early interpretation of the Froya database of gale force coastal winds from mid-Norway (Andersen, O.J. and J. Lovseth, Gale force maritime wind. The Froya data base. Part 1: Sites and instrumentation. Review of the data base, Journal of Wind

  18. Spatial modelling of wind speed around windbreaks

    NARCIS (Netherlands)

    Vigiak, O.; Sterk, G.; Warren, A.; Hagen, L.J.

    2003-01-01

    This paper presents a model to integrate windbreak shelter effects into a Geographic Information System (GIS). The GIS procedure incorporates the 1999 version windbreak sub-model of the Wind Erosion Prediction System (WEPS). Windbreak shelter is modeled in terms of friction velocity reduction, which

  19. Comparison of SAR-derived wind speed with the wind energy simulation toolkit (WEST)

    Energy Technology Data Exchange (ETDEWEB)

    Beaucage, P.; Lafrance, G.; Bernier, M. [Quebec Univ., Quebec City, PQ (Canada). Institut National de la Recherche Scientifique-Eau, Terre et Environnement; Glazer, A.; Benoit, R.; Yu, W. [Environment Canada, Gatineau, PQ (Canada)

    2005-07-01

    Wind power increases with air density, wind speed, and the surface area of wind turbine blades. Wind speed increases with altitude and topographic effects such as lower surface roughness, and high pressure gradient forcing. A comparative evaluation of a mesoscale compressible community numerical model (MC2) and synthetic aperture radar satellites (SAR) was presented. Wind speed predictions were presented, and details of both models were reviewed. Features of the MC2 included non hydrostatic Euler equations; a 3-D Lagrangian advection; full physical processes; resolution to a few km; self-nesting capabilities; topography adjustable at start-up; and open sourcing. Inputs included climatological fields; geophysical fields; initial and boundary atmospheric conditions; and dynamical and physical simulation settings. Outputs included wind speed vectors, pressure, temperature and humidity. Wind measurements from SAR satellites is conducted by observing wind friction in water. Radar signals are related to sea waves by Bragg resonant scattering. A geophysical model function establishes a semi-empirical relationship between the radar signal and wind vector. Several sources of wind direction inputs for SAR included scatterometer data; FFT of wind streaks on SAR images; local gradient filters on SAR images; NWP data; offshore coastal buoys and masts data. It was noted that with SAR, wind patterns were well represented and wind accuracy was improved. Micro-scale resolution is available and further improvements are expected with the launch of new satellites. Results of various studies comparing the use of MC2 and SAR in coastal waters were presented. It was concluded that wind features are well resolved by SAR and MC2 methods. A fusion of both methods was recommended to improve coastal and offshore wind assessments. refs., tabs., figs.

  20. Flicker Mitigation by Speed Control of Permanent Magnet Synchronous Generator Variable-Speed Wind Turbines

    DEFF Research Database (Denmark)

    Hu, Weihao; Zhang, Yunqian; Chen, Zhe;

    2013-01-01

    Grid-connected wind turbines are fluctuating power sources that may produce flicker during continuous operation. This paper presents a simulation model of a MW-level variable speed wind turbine with a full-scale back-to-back power converter and permanent magnet synchronous generator (PMSG...

  1. Dynamic behavior of parked wind turbine at extreme wind speed

    DEFF Research Database (Denmark)

    Totsuka, Yoshitaka; Imamura, Hiroshi; Yde, Anders

    2016-01-01

    of standstill and idling is analyzed by time domain simulations using two different coupled aero-hydro-servo-elastic codes. Trend in modern wind turbines is development of bigger, lighter and more flexible rotors where vibration issues may cause aero-elastic instabilities which have a serious impact...

  2. Variable-Speed Wind System Design : Final Report.

    Energy Technology Data Exchange (ETDEWEB)

    Lauw, Hinan K.; Weigand, Claus H.; Marckx, Dallas A.; Electronic Power Conditioning, Inc.

    1993-10-01

    Almost from the onset of the development of wind energy conversion systems (WECS), it was known that variable-speed operation of the turbine would maximize energy capture. This study was commissioned to assess the cost, efficiency gain, reduction of the cost of energy (COE), and other operating implications of converting the existing hardware of a modern fixed-speed wind energy conversion system to variable-speed operation. The purpose of this study was to develop a preliminary design for the hardware required to allow variable-speed operation using a doubly-fed generator with an existing fixed-speed wind turbine design. The turbine selected for this study is the AWT-26 designed and built by Advanced Wind Turbines Inc. of Redmond, Washington. The lowest projected COE using this variable-speed generation system is projected to be $0.0499/kWh, compared to the lowest possible COE with fixed-speed generation which is projected to be $0.0546/kWh. This translates into a 8.6% reduction of the COE using this variable-speed generation option. The preliminary system design has advanced to where the printed circuit boards can be physically laid out based on the schematics and the system software can be written based on the control flow-charts. The core of hardware and software has been proven to be successful in earlier versions of VSG systems. The body of this report presents the results of the VSWG system development. Operation under normal and fault conditions is described in detail, the system performance for variable-speed operation is estimated and compared to the original fixed-speed system performance, and specifications for all system components (generator, power electronic converter, and system controller) are given. Costs for all components are estimated, and incremental system cost is compared to incremental energy production. Finally, operational features of the VSWG which are not available in the existing FSWG system are outlined.

  3. ARE660 Wind Generator: Low Wind Speed Technology for Small Turbine Development

    Energy Technology Data Exchange (ETDEWEB)

    Robert W. Preus; DOE Project Officer - Keith Bennett

    2008-04-23

    This project is for the design of a wind turbine that can generate most or all of the net energy required for homes and small businesses in moderately windy areas. The purpose is to expand the current market for residential wind generators by providing cost effective power in a lower wind regime than current technology has made available, as well as reduce noise and improve reliability and safety. Robert W. Preus’ experience designing and/or maintaining residential wind generators of many configurations helped identify the need for an improved experience of safety for the consumer. Current small wind products have unreliable or no method of stopping the wind generator in fault or high wind conditions. Consumers and their neighbors do not want to hear their wind generators. In addition, with current technology, only sites with unusually high wind speeds provide payback times that are acceptable for the on-grid user. Abundant Renewable Energy’s (ARE) basic original concept for the ARE660 was a combination of a stall controlled variable speed small wind generator and automatic fail safe furling for shutdown. The stall control for a small wind generator is not novel, but has not been developed for a variable speed application with a permanent magnet alternator (PMA). The fail safe furling approach for shutdown has not been used to our knowledge.

  4. Survey of variable speed operation of wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, Ola; Hylander, J.; Thorborg, K. [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Electric Power Engineering

    1996-12-01

    During the last five years the production and operation of variable-speed wind turbines have advanced from a few experimental machines to a serial production of at least 10 MW of installed capacity of variable speed machines per week. The rated power of serial wind turbines is today around 600 kW and for the prototypes up to 3000 kW. Variable speed operation of wind turbines can be obtained with several different types of electrical generating systems, such as synchronous generators with diode rectifiers and thyristor inverters or induction generators with IGBT-converters, for the wide speed range. For the narrow speed range the wound motor induction generator with a rotor cascade or a controlled rotor resistance is preferable. The development of permanent magnetic material and the reduction of costs of the power electronic components have opened a possibility of designing cost-effective wind turbines with a directly driven generator. Pitch control together with variable speed will make it possible to limit the power variation within a few percent, 2 to 5 %, of the rated power. 7 refs, 4 figs, 2 tabs

  5. The interaction of the galactic cosmic rays with the high-speed solar wind streams

    Science.gov (United States)

    Klyuyeva, A. I.

    2014-12-01

    Based on statistical and comparative analysis of neutron monitor data from 1995 to 2013 years the influence of recurrent and sporadic high-speed streams of solar wind on the intensity of the galactic cosmic rays near Earth orbit was studied. Both types of high-speed solar wind streams modulate the galactic cosmic rays flux and cause Forbush decreases of different nature. The main parameters of Forbush decreases such as typical shape, magnitude, duration of decrease, delay, size of modulation area etc was studied.

  6. Estimated wind speed feed forward control for wind turbine operation optimisation

    Energy Technology Data Exchange (ETDEWEB)

    Van der Hooft, E.L.; Van Engelen, T.G. [ECN Wind Energy, Petten (Netherlands)

    2004-11-01

    For a pitch controlled variable speed wind turbine, a feed forward control structure based on the estimation of rotor averaged wind speed has been developed and analyzed. The additional control action will accelerate ordinary rotor speed feedback control to resist disturbances of wind speed turbulence and wind gusts. Wind speed estimation is based on reconstruction of aerodynamic torque from measurements and a priori knowledge of rotor behaviour. The theoretical base arises from the energy balance between captured aerodynamic energy from wind on the one hand and extracted electric energy (generator), stored kinetic energy (rotor inertia) and losses on the other hand. A tabular implementation for use in real-time control has been derived and evaluated by time domain simulations, stability analysis and parametric uncertainty studies. Without stability drawbacks, the proposed method has shown to be a powerful for reduction of rotor speed variations (30-40%) and wind gust suppression. Energy yield increase is feasible (0.9%) if temporarily torque excesses are not allowed.

  7. Modeling and Application of PMSG Based Variable Speed Wind Generation System

    OpenAIRE

    S. Sajedi; F. Khalifeh; T. Karimi; Z. Khalifeh

    2012-01-01

    In the early development of wind energy, the majority of wind turbines were operated at constant speed. Recently, the number of variable-speed wind turbines installed in wind farms has increased and more wind turbine manufacturers are making variable-speed wind turbines. In this study maximum power control of wind turbine and permanent magnet synchronous generator connected with two back to back voltage source converters to grid are studied. Machine currents are controlled by indirect vector ...

  8. What geometrical factors determine the in situ solar wind speed?

    CERN Document Server

    Li, Bo; Xia, Li-Dong

    2011-01-01

    At present it remains to address why the fast solar wind is fast and the slow wind is slow. Recently we have shown that the field line curvature may substantially influence the wind speed $v$, thereby offering an explanation for the Arge et al. finding that $v$ depends on more than just the flow tube expansion factor. Here we show by extensive numerical examples that the correlation between $v$ and field line curvature is valid for rather general base boundary conditions and for rather general heating functions. Furthermore, the effect of field line curvature is even more pronounced when the proton-alpha particle speed difference is examined. We suggest that any solar wind model has to take into account the field line shape for any quantitative analysis to be made.

  9. WIND TURBINE OPERATION PARAMETER CHARACTERISTICS AT A GIVEN WIND SPEED

    Directory of Open Access Journals (Sweden)

    Zdzisław Kamiński

    2014-06-01

    Full Text Available This paper discusses the results of the CFD simulation of the flow around Vertical Axis Wind Turbine rotor. The examined rotor was designed following patent application no. 402214. The turbine operation is characterised by parameters, such as opening angle of blades, power, torque, rotational velocity at a given wind velocity. Those parameters have an impact on the performance of entire assembly. The distribution of forces acting on the working surfaces in the turbine can change, depending on the angle of rotor rotation. Moreover, the resultant force derived from the force acting on the oncoming and leaving blades should be as high as possible. Accordingly, those parameters were individually simulated over time for each blade in three complete rotations. The attempts to improve the performance of the entire system resulted in a new research trend to improve the performance of working turbine rotor blades.

  10. Reduced wind speed improves plant growth in a desert city.

    Directory of Open Access Journals (Sweden)

    Christofer Bang

    Full Text Available BACKGROUND: The often dramatic effects of urbanization on community and ecosystem properties, such as primary productivity, abundances, and diversity are now well-established. In most cities local primary productivity increases and this extra energy flows upwards to alter diversity and relative abundances in higher trophic levels. The abiotic mechanisms thought to be responsible for increases in urban productivity are altered temperatures and light regimes, and increased nutrient and water inputs. However, another abiotic factor, wind speed, is also influenced by urbanization and well known for altering primary productivity in agricultural systems. Wind effects on primary productivity have heretofore not been studied in the context of urbanization. METHODOLOGY/PRINCIPAL FINDINGS: We designed a field experiment to test if increased plant growth often observed in cities is explained by the sheltering effects of built structures. Wind speed was reduced by protecting Encelia farinosa (brittlebush plants in urban, desert remnant and outlying desert localities via windbreaks while controlling for water availability and nutrient content. In all three habitats, we compared E. farinosa growth when protected by experimental windbreaks and in the open. E. farinosa plants protected against ambient wind in the desert and remnant areas grew faster in terms of biomass and height than exposed plants. As predicted, sheltered plants did not differ from unprotected plants in urban areas where wind speed is already reduced. CONCLUSION/SIGNIFICANCE: Our results indicate that reductions in wind speed due to built structures in cities contribute to increased plant productivity and thus also to changes in abundances and diversity of higher trophic levels. Our study emphasizes the need to incorporate wind speed in future urban ecological studies, as well as in planning for green space and sustainable cities.

  11. Higher-than-predicted saltation threshold wind speeds on Titan

    Science.gov (United States)

    Burr, Devon M.; Bridges, Nathan T.; Marshall, John R.; Smith, James K.; White, Bruce R.; Emery, Joshua P.

    2015-01-01

    Titan, the largest satellite of Saturn, exhibits extensive aeolian, that is, wind-formed, dunes, features previously identified exclusively on Earth, Mars and Venus. Wind tunnel data collected under ambient and planetary-analogue conditions inform our models of aeolian processes on the terrestrial planets. However, the accuracy of these widely used formulations in predicting the threshold wind speeds required to move sand by saltation, or by short bounces, has not been tested under conditions relevant for non-terrestrial planets. Here we derive saltation threshold wind speeds under the thick-atmosphere, low-gravity and low-sediment-density conditions on Titan, using a high-pressure wind tunnel refurbished to simulate the appropriate kinematic viscosity for the near-surface atmosphere of Titan. The experimentally derived saltation threshold wind speeds are higher than those predicted by models based on terrestrial-analogue experiments, indicating the limitations of these models for such extreme conditions. The models can be reconciled with the experimental results by inclusion of the extremely low ratio of particle density to fluid density on Titan. Whereas the density ratio term enables accurate modelling of aeolian entrainment in thick atmospheres, such as those inferred for some extrasolar planets, our results also indicate that for environments with high density ratios, such as in jets on icy satellites or in tenuous atmospheres or exospheres, the correction for low-density-ratio conditions is not required.

  12. Mitigation of Wind Power Fluctuation by Active Current Control of Variable Speed Wind Turbines

    DEFF Research Database (Denmark)

    Zhang, Yunqian; Chen, Zhe; Hu, Weihao

    2013-01-01

    Wind shear and tower shadow are the sources of power fluctuation of grid connected wind turbines during continuous operation. This paper presents a simulation model of a MW-level doubly fed induction generator (DFIG) based variable speed wind turbine with a partial-scale back-to-back power conver...... of the wind turbine. The simulations are performed on the NREL 1.5MW upwind reference wind turbine model. The simulation results are presented and discussed to demonstrate the validity of the proposed control method....

  13. Band Depth Clustering for Nonstationary Time Series and Wind Speed Behavior

    OpenAIRE

    Tupper, Laura L.; Matteson, David S.; Anderson, C. Lindsay

    2015-01-01

    We explore the behavior of wind speed over time, using the Eastern Wind Dataset published by the National Renewable Energy Laboratory. This dataset gives wind speeds over three years at hundreds of potential wind farm sites. Wind speed analysis is necessary to the integration of wind energy into the power grid; short-term variability in wind speed affects decisions about usage of other power sources, so that the shape of the wind speed curve becomes as important as the overall level. To asses...

  14. Operational Modal Analysis of Wind Turbine Speed-increase Gearbox

    Directory of Open Access Journals (Sweden)

    LI Yafeng

    2013-11-01

    Full Text Available Speed increase transmission gear box is the primary vibration and noise source of wind turbine, Operational modal method was adopted to collect impact data and response data of each point based on the gearbox test model. ANSYS finite element model is established to simulate the wind turbine gearbox. Then the modal frequencies of the two methods were compared to ensure the test model is correct. The results show that operational modal method can be applied in wind turbine gearbox modal analysis and it has important guiding significance to gearbox fault diagnosis and reliability and maintainability improving.  

  15. Calibration of a spinner anemometer for wind speed measurements

    DEFF Research Database (Denmark)

    Demurtas, Giorgio; Friis Pedersen, Troels; Zahle, Frederik

    2016-01-01

    of the spinner anemometer is based on the flow distortion caused by the wind turbine spinner. The flow on the spinner surface is measured by means of three 1D sonic sensors mounted on the spinner and a conversion algorithm to convert the wind velocity components measured by the three sonic sensors to horizontal...... wind speed, yaw misalignment and flow inclination angle. The algorithm utilizes two calibration constants that are specific to the spinner shape, blade root design and to the mounting positions of the sonic sensors on the spinner. The present analysis describes methods to determine the calibration......The power curve of a wind turbine can be measured, according to IEC 61400-12-2 with a nacelle-mounted anemometer. Typically, a sonic anemometer or a cup anemometer and a wind vane are mounted on the back of the nacelle roof. Another option is to use a spinner anemometer. The measurement principle...

  16. On Using Wind Speed Preview to Reduce Wind Turbine Tower Oscillations

    DEFF Research Database (Denmark)

    Kristalny, Maxim; Madjidian, Daria; Knudsen, Torben

    2013-01-01

    We investigate the potential of using previewed wind speed measurements for damping wind turbine fore-aft tower oscillations. Using recent results on continuous-time H 2 preview control, we develop a numerically efficient framework for the feedforward controller synthesis. One of the major benefits...

  17. Wind tunnel experiments to prove a hydraulic passive torque control concept for variable speed wind turbines

    NARCIS (Netherlands)

    Diepeveen, N.F.B.; Jarquin-Laguna, A.

    2014-01-01

    In this paper the results are presented of experiments to prove an innovative concept for passive torque control of variable speed wind turbines using fluid power technology. It is demonstrated that by correctly configuring the hydraulic drive train, the wind turbine rotor operates at or near maximu

  18. Wind tunnel experiments to prove a hydraulic passive torque control concept for variable speed wind turbines

    NARCIS (Netherlands)

    Diepeveen, N.F.B.; Jarquin-Laguna, A.

    2014-01-01

    In this paper the results are presented of experiments to prove an innovative concept for passive torque control of variable speed wind turbines using fluid power technology. It is demonstrated that by correctly configuring the hydraulic drive train, the wind turbine rotor operates at or near maximu

  19. The dependence of wind stress on wave height and wind speed

    Science.gov (United States)

    Blake, Reginald A.

    1991-01-01

    Three near-neutral boundary layer data sets were investigated with the aim of finding a dependence of wind stress on both wind speed and significant wave height. The data set most representative of open-ocean wave height, wind speed, and momentum flux conditions, was selected and analyzed by means of the least-squares method to produce a new parameterization for the wind stress as a function of both wind speed and significant wave height. This study shows that the wind stress, and consequently the drag coefficient, decreases with increasing wave height for a fixed wind speed. The study also shows that the curvature of the wind profile decreases with increasing wave height and that the C(DN) = A + BU-bar(10) form for the drag coefficient parameterization is inadequate. A drag coefficient that applies to both smooth and rough flows is proposed. These results are more applicable for open-ocean deep-water conditions and less applicable for sheltered, closed, shallow water sites.

  20. Complete methodology on generating realistic wind speed profiles based on measurements

    DEFF Research Database (Denmark)

    Gavriluta, Catalin; Spataru, Sergiu; Mosincat, Ioan

    2012-01-01

    The wind speed represents the main exogenous signal applied to a Wind Energy Conversion System (WECS) and determines its behavior. The erratic variation of the wind speed, highly dependent on the given site and on the atmospheric conditions, makes the wind speed quite difficult to model. Moreover...

  1. Modulation of Saturn's radio clock by solar wind speed.

    Science.gov (United States)

    Zarka, Philippe; Lamy, Laurent; Cecconi, Baptiste; Prangé, Renée; Rucker, Helmut O

    2007-11-08

    The internal rotation rates of the giant planets can be estimated by cloud motions, but such an approach is not very precise because absolute wind speeds are not known a priori and depend on latitude: periodicities in the radio emissions, thought to be tied to the internal planetary magnetic field, are used instead. Saturn, despite an apparently axisymmetric magnetic field, emits kilometre-wavelength (radio) photons from auroral sources. This emission is modulated at a period initially identified as 10 h 39 min 24 +/- 7 s, and this has been adopted as Saturn's rotation period. Subsequent observations, however, revealed that this period varies by +/-6 min on a timescale of several months to years. Here we report that the kilometric radiation period varies systematically by +/-1% with a characteristic timescale of 20-30 days. Here we show that these fluctuations are correlated with solar wind speed at Saturn, meaning that Saturn's radio clock is controlled, at least in part, by conditions external to the planet's magnetosphere. No correlation is found with the solar wind density, dynamic pressure or magnetic field; the solar wind speed therefore has a special function. We also show that the long-term fluctuations are simply an average of the short-term ones, and therefore the long-term variations are probably also driven by changes in the solar wind.

  2. Variable Speed Wind Turbines Capability for Temporary Over-Production

    DEFF Research Database (Denmark)

    Tarnowski, Germán Claudio; Kjær, Philip Carne; Sørensen, Poul Ejnar

    2009-01-01

    New control systems for Variable Speed Wind Turbines (VSWT) need to be developed in order to provide inertia response and frequency control to support the grid. This work studies the behavior and capability of VSWT for providing temporary active power overproduction. The study is conducted on a m...

  3. The Link Between Mineral Dust and Wind Speed: Implications for Wind Energy in the Maghreb

    Science.gov (United States)

    McGraw, Z.; Storelvmo, T.

    2014-12-01

    Airborne dust is capable of degrading wind turbine performance. This will be a particularly salient consideration for future schemes to utilize wind energy in the Maghreb, a region of Africa marked by the presence of the Sahara desert, the world's largest source of mineral dust. In this study we analyzed the correlation between wind speed and the existence of dust in measurements pertaining to the region. Wind speed data was acquired from meteorological masts along with reanalysis output. Comparisons were made to the presence of polluted and desert dust as identified by CALIOP, a satellite-based lidar instrument, and to coarse-mode Aerosol Optical Depth (AOD) measurements from the AERONET network of sun photometers. It was anticipated that results would evidence the existence of a critical wind speed that is required for the emission of noticeable desert dust. The proximity of this threshold to the ideal range of wind speeds for turbine efficiency can potentially influence the feasibility of harvesting wind energy in the region.

  4. Verification of high-speed solar wind stream forecasts using operational solar wind models

    DEFF Research Database (Denmark)

    Reiss, Martin A.; Temmer, Manuela; Veronig, Astrid M.

    2016-01-01

    High-speed solar wind streams emanating from coronal holes are frequently impinging on the Earth's magnetosphere causing recurrent, medium-level geomagnetic storm activity. Modeling high-speed solar wind streams is thus an essential element of successful space weather forecasting. Here we evaluate...... high-speed stream forecasts made by the empirical solar wind forecast (ESWF) and the semiempirical Wang-Sheeley-Arge (WSA) model based on the in situ plasma measurements from the Advanced Composition Explorer (ACE) spacecraft for the years 2011 to 2014. While the ESWF makes use of an empirical relation...... between the coronal hole area observed in Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) images and solar wind properties at the near-Earth environment, the WSA model establishes a link between properties of the open magnetic field lines extending from the photosphere to the corona...

  5. Speed Synchronization of web winding System with Sliding Mode Control

    Directory of Open Access Journals (Sweden)

    Hachemi Glaoui

    2013-02-01

    Full Text Available A continuous web winding system is a large-scale, complex interconnected dynamic system with numerous tension zones to transport the web while processing it. There are two control schemes for large-scale system control: the centralized scheme and the decentralized scheme. Centralized control is the traditional control method, which considers all the information about the system to be a single dynamic model and design a control system for this model. A speed synchronization control strategy for multiple induction motors, based on adjacent cross-coupling control structure, is developed by employing total sliding mode control method. The proposed control strategy is to stabilize speed tracking of each induction motor while synchronizing its speed with the speed of the other motors so as to make speed synchronization error amongst induction motors converge to zero. The global stability and the convergence of the designed controller are proved by using Lyapunov method. Simulation results demonstrate the effectiveness of the proposed method.

  6. Complete methodology on generating realistic wind speed profiles based on measurements

    DEFF Research Database (Denmark)

    Gavriluta, Catalin; Spataru, Sergiu; Mosincat, Ioan;

    2012-01-01

    , wind modelling for medium and large time scales is poorly treated in the present literature. This paper presents methods for generating realistic wind speed profiles based on real measurements. The wind speed profile is divided in a low- frequency component (describing long term variations......The wind speed represents the main exogenous signal applied to a Wind Energy Conversion System (WECS) and determines its behavior. The erratic variation of the wind speed, highly dependent on the given site and on the atmospheric conditions, makes the wind speed quite difficult to model. Moreover...

  7. Doubly Fed Drives for Variable Speed Wind Turbines

    DEFF Research Database (Denmark)

    Lindholm, Morten

    2004-01-01

    This thesis deals with the use of variable speed wind turbines. Different wind turbine generator topologies are described. In particular, the reduced variable speed turbine, which uses a doubly fed induction generator, is covered. An overview of the power electronic inverters of interest...... in the machine is nearly constant. This means that changes of either the flux or torque producing current in the rotor circuit is limited by the transient time constant of the machine. A 40 kW laboratory model with a doubly fed induction generator and a 3-level neutral point clamped back to back power converter...... is constructed. Adaptive active flters are used to reduce harmonics and slip harmonics in the stator current. The flters are implemented in both inverters. The active flters reduce the stator harmonics by 20-30 dB. The flters can reduce the slip harmonics at variable speed....

  8. Hi-Q Rotor - Low Wind Speed Technology

    Energy Technology Data Exchange (ETDEWEB)

    Todd E. Mills; Judy Tatum

    2010-01-11

    The project objective was to optimize the performance of the Hi-Q Rotor. Early research funded by the California Energy Commission indicated the design might be advantageous over state-of-the-art turbines for collecting wind energy in low wind conditions. The Hi-Q Rotor is a new kind of rotor targeted for harvesting wind in Class 2, 3, and 4 sites, and has application in areas that are closer to cities, or 'load centers.' An advantage of the Hi-Q Rotor is that the rotor has non-conventional blade tips, producing less turbulence, and is quieter than standard wind turbine blades which is critical to the low-wind populated urban sites. Unlike state-of-the-art propeller type blades, the Hi-Q Rotor has six blades connected by end caps. In this phase of the research funded by DOE's Inventions and Innovation Program, the goal was to improve the current design by building a series of theoretical and numeric models, and composite prototypes to determine a best of class device. Development of the rotor was performed by aeronautical engineering and design firm, DARcorporation. From this investigation, an optimized design was determined and an 8-foot diameter, full-scale rotor was built and mounted using a Bergey LX-1 generator and furling system which were adapted to support the rotor. The Hi-Q Rotor was then tested side-by-side against the state-of-the-art Bergey XL-1 at the Alternative Energy Institute's Wind Test Center at West Texas State University for six weeks, and real time measurements of power generated were collected and compared. Early wind tunnel testing showed that the cut-in-speed of the Hi-Q rotor is much lower than a conventional tested HAWT enabling the Hi-Q Wind Turbine to begin collecting energy before a conventional HAWT has started spinning. Also, torque at low wind speeds for the Hi-Q Wind Turbine is higher than the tested conventional HAWT and enabled the wind turbine to generate power at lower wind speeds. Based on the data

  9. Short-term wind speed predictions with machine learning techniques

    Science.gov (United States)

    Ghorbani, M. A.; Khatibi, R.; FazeliFard, M. H.; Naghipour, L.; Makarynskyy, O.

    2016-02-01

    Hourly wind speed forecasting is presented by a modeling study with possible applications to practical problems including farming wind energy, aircraft safety and airport operations. Modeling techniques employed in this paper for such short-term predictions are based on the machine learning techniques of artificial neural networks (ANNs) and genetic expression programming (GEP). Recorded values of wind speed were used, which comprised 8 years of collected data at the Kersey site, Colorado, USA. The January data over the first 7 years (2005-2011) were used for model training; and the January data for 2012 were used for model testing. A number of model structures were investigated for the validation of the robustness of these two techniques. The prediction results were compared with those of a multiple linear regression (MLR) method and with the Persistence method developed for the data. The model performances were evaluated using the correlation coefficient, root mean square error, Nash-Sutcliffe efficiency coefficient and Akaike information criterion. The results indicate that forecasting wind speed is feasible using past records of wind speed alone, but the maximum lead time for the data was found to be 14 h. The results show that different techniques would lead to different results, where the choice between them is not easy. Thus, decision making has to be informed of these modeling results and decisions should be arrived at on the basis of an understanding of inherent uncertainties. The results show that both GEP and ANN are equally credible selections and even MLR should not be dismissed, as it has its uses.

  10. Short-term wind-speed forecasting system for wind power applications

    Science.gov (United States)

    Traiteur, J. J.; Baidya Roy, S.

    2010-12-01

    Accurate short-term wind speed forecasts for utility-scale large wind farms will be crucial for the U.S. Department of Energy's goal of providing 20% of total electricity from wind by 2030. Communicating the level of uncertainty in these wind speed forecasts will allow the industry to better quantify the level of financial risk inherent with these forecasts. In this study, a computationally efficient and accurate system for short-term (0-60 mins) forecasting of wind speed is developed. This system uses a 27 member ensemble of the Weather Research and Forecasting Single-Column Model (WRF-SCM) to generate a probability density function (pdf) of daytime forecasts at 90m height for a location in Chalmers Township in West/Central Illinois. The WRF-SCM ensemble is initialized by the 20km Rapid Update Cycle (RUC) 00h forecast and perturbed by both perturbations in the initial conditions and physics options. The pdf is calibrated using Bayesian Model Averaging (BMA) where the individual forecasts are weighted according to their performance. This combination of a numerical weather prediction ensemble system and Bayesian statistics allows for accurate and computationally efficient prediction of 1 hour wind speed and the level of uncertainty in the forecasts.

  11. A short-term ensemble wind speed forecasting system for wind power applications

    Science.gov (United States)

    Baidya Roy, S.; Traiteur, J. J.; Callicutt, D.; Smith, M.

    2011-12-01

    This study develops an adaptive, blended forecasting system to provide accurate wind speed forecasts 1 hour ahead of time for wind power applications. The system consists of an ensemble of 21 forecasts with different configurations of the Weather Research and Forecasting Single Column Model (WRFSCM) and a persistence model. The ensemble is calibrated against observations for a 2 month period (June-July, 2008) at a potential wind farm site in Illinois using the Bayesian Model Averaging (BMA) technique. The forecasting system is evaluated against observations for August 2008 at the same site. The calibrated ensemble forecasts significantly outperform the forecasts from the uncalibrated ensemble while significantly reducing forecast uncertainty under all environmental stability conditions. The system also generates significantly better forecasts than persistence, autoregressive (AR) and autoregressive moving average (ARMA) models during the morning transition and the diurnal convective regimes. This forecasting system is computationally more efficient than traditional numerical weather prediction models and can generate a calibrated forecast, including model runs and calibration, in approximately 1 minute. Currently, hour-ahead wind speed forecasts are almost exclusively produced using statistical models. However, numerical models have several distinct advantages over statistical models including the potential to provide turbulence forecasts. Hence, there is an urgent need to explore the role of numerical models in short-term wind speed forecasting. This work is a step in that direction and is likely to trigger a debate within the wind speed forecasting community.

  12. Grid impact of variable-speed wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Larsson, Aa. [Chalmers Univ. of Technology, Dept. of Electric Power Engineering, Goeteborg (Sweden); Soerensen, P. [Risoe National Lab., Roskilde (Denmark); Santjer, F. [German Wind Energy Inst., DEWI, Wilhelmshaven (Germany)

    1999-03-01

    In this paper the power quality of variable-speed wind turbines equipped with forced-commutated inverters is investigated. Measurements have been taken on the same type of variable-speed wind turbines in Germany and Sweden. The measurements have been analysed according to existing IEC standards. Special attention has been paid to the aggregation of several wind turbines on flicker emission and harmonics. The aggregation has been compared with the summation laws used in the draft IEC 61400-21 `Power Quality Requirements for Grid Connected wind turbines`. The methods for calculating and summing flicker proposed by IEC Standards are reliable. Harmonics and inter-harmonics are treated in IEC 61000-4-7 and IEC 61000-3-6. The methods for summing harmonics and inter-harmonics in IEC 61000-3-6 are applicable to wind turbines. In order to obtain a correct magnitude of the frequency components, the use of a well-defined window width, according to IEC 61000-4-7 Amendment 1 is of a great importance. (au)

  13. 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.

  14. Incorporating geostrophic wind information for improved space–time short-term wind speed forecasting

    KAUST Repository

    Zhu, Xinxin

    2014-09-01

    Accurate short-term wind speed forecasting is needed for the rapid development and efficient operation of wind energy resources. This is, however, a very challenging problem. Although on the large scale, the wind speed is related to atmospheric pressure, temperature, and other meteorological variables, no improvement in forecasting accuracy was found by incorporating air pressure and temperature directly into an advanced space-time statistical forecasting model, the trigonometric direction diurnal (TDD) model. This paper proposes to incorporate the geostrophic wind as a new predictor in the TDD model. The geostrophic wind captures the physical relationship between wind and pressure through the observed approximate balance between the pressure gradient force and the Coriolis acceleration due to the Earth’s rotation. Based on our numerical experiments with data from West Texas, our new method produces more accurate forecasts than does the TDD model using air pressure and temperature for 1to 6-hour-ahead forecasts based on three different evaluation criteria. Furthermore, forecasting errors can be further reduced by using moving average hourly wind speeds to fit the diurnal pattern. For example, our new method obtains between 13.9% and 22.4% overall mean absolute error reduction relative to persistence in 2-hour-ahead forecasts, and between 5.3% and 8.2% reduction relative to the best previous space-time methods in this setting.

  15. Performance Investigation of A Mix Wind Turbine Using A Clutch Mechanism At Low Wind Speed Condition

    Science.gov (United States)

    Jamanun, M. J.; Misaran, M. S.; Rahman, M.; Muzammil, W. K.

    2017-07-01

    Wind energy is one of the methods that generates energy from sustainable resources. This technology has gained prominence in this era because it produces no harmful product to the society. There is two fundamental type of wind turbine are generally used this day which is Horizontal axis wind turbine (HAWT) and Vertical axis wind turbine (VAWT). The VAWT technology is more preferable compare to HAWT because it gives better efficiency and cost effectiveness as a whole. However, VAWT is known to have distinct disadvantage compared to HAWT; self-start ability and efficiency at low wind speed condition. Different solution has been proposed to solve these issues which includes custom design blades, variable angle of attack mechanism and mix wind turbine. A new type of clutch device was successfully developed in UMS to be used in a mix Savonius-Darrieus wind turbine configuration. The clutch system which barely audible when in operation compared to a ratchet clutch system interconnects the Savonius and Darrieus rotor; allowing the turbine to self-start at low wind speed condition as opposed to a standalone Darrieus turbine. The Savonius height were varied at three different size in order to understand the effect of the Savonius rotor to the mix wind turbine performance. The experimental result shows that the fabricated Savonius rotor show that the height of the Savonius rotor affecting the RPM for the turbine. The swept area (SA), aspect ratio (AR) and tip speed ratio (TSR) also calculated in this paper. The highest RPM recorded in this study is 90 RPM for Savonius rotor 0.22-meter height at 2.75 m/s. The Savonius rotor 0.22-meter also give the highest TSR for each range of speed from 0.75 m/s, 1.75 m/s and 2.75 m/s where it gives 1.03 TSR, 0.76 TSR, and 0.55 TSR.

  16. 9x15 Low Speed Wind Tunnel Improvements Update

    Science.gov (United States)

    Stephens, David

    2017-01-01

    The 9- by 15-Foot Low Speed Wind Tunnel (9x15 LSWT) at NASA Glenn Research Center was built in 1969 in the return leg of the 8- by 6-Foot Supersonic Wind Tunnel (8x6 SWT). The 9x15 LSWT was designed for performance testing of VSTOL aircraft models, but with the addition of the current acoustic treatment in 1986 the tunnel been used principally for acoustic and performance testing of aircraft propulsion systems. The present document describes an anticipated acoustic upgrade to be completed in 2018.

  17. 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.

  18. An Improved Wind Speed Retrieval Algorithm For The CYGNSS Mission

    Science.gov (United States)

    Ruf, C. S.; Clarizia, M. P.

    2015-12-01

    The NASA spaceborne Cyclone Global Navigation Satellite System (CYGNSS) mission is a constellation of 8 microsatellites focused on tropical cyclone (TC) inner core process studies. CYGNSS will be launched in October 2016, and will use GPS-Reflectometry (GPS-R) to measure ocean surface wind speed in all precipitating conditions, and with sufficient frequency to resolve genesis and rapid intensification. Here we present a modified and improved version of the current baseline Level 2 (L2) wind speed retrieval algorithm designed for CYGNSS. An overview of the current approach is first presented, which makes use of two different observables computed from 1-second Level 1b (L1b) delay-Doppler Maps (DDMs) of radar cross section. The first observable, the Delay-Doppler Map Average (DDMA), is the averaged radar cross section over a delay-Doppler window around the DDM peak (i.e. the specular reflection point coordinate in delay and Doppler). The second, the Leading Edge Slope (LES), is the leading edge of the Integrated Delay Waveform (IDW), obtained by integrating the DDM along the Doppler dimension. The observables are calculated over a limited range of time delays and Doppler frequencies to comply with baseline spatial resolution requirements for the retrieved winds, which in the case of CYGNSS is 25 km. In the current approach, the relationship between the observable value and the surface winds is described by an empirical Geophysical Model Function (GMF) that is characterized by a very high slope in the high wind regime, for both DDMA and LES observables, causing large errors in the retrieval at high winds. A simple mathematical modification of these observables is proposed, which linearizes the relationship between ocean surface roughness and the observables. This significantly reduces the non-linearity present in the GMF that relate the observables to the wind speed, and reduces the root-mean square error between true and retrieved winds, particularly in the high wind

  19. Design of PVC Bladed Horizontal Axis Wind Turbine for Low Wind Speed Region

    Directory of Open Access Journals (Sweden)

    Vicky K Rathod

    2014-07-01

    Full Text Available The Project is aimed at designing a wind turbine that can be able to build by Laypersons, using readily available material which is feasible & affordable to provide much needed electricity. Since most of the high wind power density regions in the zone of high wind speed are already being tapped by large scale wind turbine and so it required creating a large scope for the development of low wind speed turbines. Our study focuses primarily on designing the blade for tapping power in the regions of low wind power density. The aerodynamic profiles of wind turbine blades have major influence on aerodynamic efficiency of wind turbine. This can be achieved by comparing the effectiveness of a crude blade fashioned from a different Size, Material & standard of PVC drainage pipe which are easily available in market. It can be evaluated by performing experimental analysis, data collection & its evaluation on different type & size of PVC Pipe & preparing an analytical tool for best Design.

  20. Reactive power control methods for improved reliability of wind power inverters under wind speed variations

    DEFF Research Database (Denmark)

    Ma, Ke; Liserre, Marco; Blaabjerg, Frede

    2012-01-01

    The thermal cycling of power switching devices may lead to failures that compromise the reliability of power converters. Wind Turbine Systems (WTS) are especially subject to severe thermal cycling which may be caused by the wind speed variations or power grid faults. This paper proposes a control...... in the most stressed devices. The possible model-based control system for the proposed method is demonstrated, designed and simulated based on the Three-level Neutral-Point- Clamped (3L-NPC) grid-connected converters. It is concluded that with the proposed reactive power control method, the junction...... method to relieve the thermal cycling of power switching devices under severe wind speed variations, by circulating reactive power among the parallel power converters in a WTS or among the WTS's in a wind park. The amount of reactive power is adjusted to limit the junction temperature fluctuation...

  1. AC-DC integrated load flow calculation for variable speed offshore wind farms

    DEFF Research Database (Denmark)

    Zhao, Menghua; Chen, Zhe; Blaabjerg, Frede

    2005-01-01

    This paper proposes a sequential AC-DC integrated load flow algorithm for variable speed offshore wind farms. In this algorithm, the variable frequency and the control strategy of variable speed wind turbine systems are considered. In addition, the losses of wind turbine systems and the losses...... of converters are also integrated into the load flow algorithm. As a general algorithm, it can be applied to different types of wind farm configurations, and the load flow is related to the wind speed....

  2. Generation of Random Wind Speed Profiles for Evaluation of Stress in WT Power Converters

    OpenAIRE

    Pigazo, Alberto; Qin, Zian; Liserre, Marco; Blaabjerg, Frede

    2013-01-01

    Wind turbines are subjected to wind speed variations that cause a power profile that will stress the overall system. This stress is tranfered to the power converter, resulting in temperature variations of the power devices and, hence, causing the reduction of the lifetime. The lifetime expectation changes depending on the real wind speed once the wind turbine is operating. Usually, the real wind speed profiles are employed to evaluate this stress but they do not consider all possible operatio...

  3. Near surface spatially averaged air temperature and wind speed determined by acoustic travel time tomography

    Directory of Open Access Journals (Sweden)

    Armin Raabe

    2001-03-01

    Full Text Available Acoustic travel time tomography is presented as a possibility for remote monitoring of near surface airtemperature and wind fields. This technique provides line-averaged effective sound speeds changing with temporally and spatially variable air temperature and wind vector. The effective sound speed is derived from the travel times of sound signals which propagate at defined paths between different acoustic sources and receivers. Starting with the travel time data a tomographic algorithm (Simultaneous Iterative Reconstruction Technique, SIRT is used to calculate area-averaged air temperature and wind speed. The accuracy of the experimental method and the tomographic inversion algorithm is exemplarily demonstrated for one day without remarkable differences in the horizontal temperature field, determined by independent in situ measurements at different points within the measuring field. The differences between the conventionally determined air temperature (point measurement and the air temperature determined by tomography (area-averaged measurement representative for the area of the measuring field 200m x 260m were below 0.5 K for an average of 10 minutes. The differences obtained between the wind speed measured at a meteorological mast and calculated from acoustic measurements are not higher than 0.5 ms-1 for the same averaging time. The tomographically determined area-averaged distribution of air temperature (resolution 50 m x 50 m can be used to estimate the horizontal gradient of air temperature as a pre-condition to detect horizontal turbulent fluxes of sensible heat.

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

    DEFF Research Database (Denmark)

    Østergaard, Kasper Zinck; Stoustrup, Jakob; Brath, Per

    2007-01-01

    This paper addresses state estimation and linear quadratic (LQ) control of variable speed variable pitch wind turbines. On the basis of a nonlinear model of a wind turbine, a set of operating conditions is identified and a LQ controller is designed for each operating point. The controller gains....... Simulation results are given that display good performance of the observers and comparisons with a controller designed by classical methods displays the potential of the method.  ...

  5. Comment on "Critical wind speed at which trees break"

    Science.gov (United States)

    Albrecht, Axel; Badel, Eric; Bonnesoeur, Vivien; Brunet, Yves; Constant, Thiéry; Défossez, Pauline; de Langre, Emmanuel; Dupont, Sylvain; Fournier, Meriem; Gardiner, Barry; Mitchell, Stephen J.; Moore, John R.; Moulia, Bruno; Nicoll, Bruce C.; Niklas, Karl J.; Schelhaas, Mart-Jan; Spatz, Hans-Christof; Telewski, Frank W.

    2016-12-01

    Virot et al. [E. Virot et al., Phys. Rev. E 93, 023001 (2016), 10.1103/PhysRevE.93.023001] assert that the critical wind speed at which ⩾50% of all trees in a population break is ≈42 m/s, regardless of tree characteristics. We show that empirical data do not support this assertion, and that the assumptions underlying the theory used by Virot et al. are inconsistent with the biomechanics of trees.

  6. Wind Speed Forecasting Using Hybrid Wavelet Transform—ARMA Techniques

    OpenAIRE

    Diksha Kaur; Tek Tjing Lie; Nirmal K. C. Nair; Brice Vallès

    2015-01-01

    The objective of this paper is to develop a novel wind speed forecasting technique, which produces more accurate prediction. The Wavelet Transform (WT) along with the Auto Regressive Moving Average (ARMA) is chosen to form a hybrid whose combination is expected to give minimum Mean Absolute Prediction Error (MAPE). A simulation study has been conducted by comparing the forecasting results using the Wavelet-ARMA with the ARMA and Artificial Neural Network (ANN)-Ensemble Kalman Filter (EnKF) hy...

  7. Active system monitoring applied on wind turbines

    DEFF Research Database (Denmark)

    Niemann, Hans Henrik; Poulsen, Niels Kjølstad; Parbo, Henrik

    2009-01-01

    A concept for active system monitoring (ASM) applied on wind turbines is presented in this paper. The concept is based on an injection of a small periodic auxiliary signal in the system. An investigation of the signature from the auxiliary input in residual (error) signals can then be applied...

  8. Multistep Wind Speed Forecasting Using a Novel Model Hybridizing Singular Spectrum Analysis, Modified Intelligent Optimization, and Rolling Elman Neural Network

    Directory of Open Access Journals (Sweden)

    Zhongshan Yang

    2016-01-01

    Full Text Available Wind speed high-accuracy forecasting, an important part of the electrical system monitoring and control, is of the essence to protect the safety of wind power utilization. However, the wind speed signals are always intermittent and intrinsic complexity; therefore, it is difficult to forecast them accurately. Many traditional wind speed forecasting studies have focused on single models, which leads to poor prediction accuracy. In this paper, a new hybrid model is proposed to overcome the shortcoming of single models by combining singular spectrum analysis, modified intelligent optimization, and the rolling Elman neural network. In this model, except for the multiple seasonal patterns used to reduce interferences from the original data, the rolling model is utilized to forecast the multistep wind speed. To verify the forecasting ability of the proposed hybrid model, 10 min and 60 min wind speed data from the province of Shandong, China, were proposed in this paper as the case study. Compared to the other models, the proposed hybrid model forecasts the wind speed with higher accuracy.

  9. Verification of high-speed solar wind stream forecasts using operational solar wind models

    CERN Document Server

    Reiss, Martin A; Veronig, Astrid M; Nikolic, Ljubomir; Vennerstrom, Susanne; Schoengassner, Florian; Hofmeister, Stefan J

    2016-01-01

    High-speed solar wind streams emanating from coronal holes are frequently impinging on the Earth's magnetosphere causing recurrent, medium-level geomagnetic storm activity. Modeling high-speed solar wind streams is thus an essential element of successful space weather forecasting. Here we evaluate high-speed stream forecasts made by the empirical solar wind forecast (ESWF) and the semiempirical Wang-Sheeley-Arge (WSA) model based on the in situ plasma measurements from the ACE spacecraft for the years 2011 to 2014. While the ESWF makes use of an empirical relation between the coronal hole area observed in Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) images and solar wind properties at the near-Earth environment, the WSA model establishes a link between properties of the open magnetic field lines extending from the photosphere to the corona and the background solar wind conditions. We found that both solar wind models are capable of predicting the large-scale features of the observed sol...

  10. Control of variable speed pitch-regulated wind turbines in strong wind conditions using a combined feedforward and feedback technique

    DEFF Research Database (Denmark)

    Feng, Ju; Shen, Wen Zhong

    2012-01-01

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

  11. Bimodal versus Weibull wind speed distributions: an analysis of wind energy potential in La Venta, Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Jaramillo, O.A.; Borja, M.A.

    2004-07-01

    The International Standard IEC 61400-12 and other international recommendations suggest the use of the two-parameter Weibull probability distribution function (PDF) to estimate the Annual Energy Production (AEP) of a wind turbine. Most of the commercial software uses the unimodal Weibull PDF as the default option to carry out estimations of AEP, which in turn, are used to optimise wind farm layouts. Furthermore, AEP is essential data to assess the economic feasibility of a wind power project. However, in some regions of the world, the use of these widely adopted and recommended methods lead to incorrect results. This is the case for the region of La Ventosa in Mexico, where the frequency of the wind speed shows a bimodal distribution. In this work, mathematical formulations by using a Weibull PDF and a bimodal distribution are established to compare the AEP, the capacity factor and the levelised production cost for a specific wind turbine. By combining one year of wind speed data with the hypothetic power performance of the Vestas V27-225 kW wind turbine, it was found that using the Weibull PDF underestimates AEP (and thus the Capacity Factor) by about 12%. (author)

  12. Decadal predictability of regional scale wind speed and wind energy potentials over Central Europe

    Science.gov (United States)

    Moemken, Julia; Reyers, Mark; Buldmann, Benjamin; Pinto, Joaquim G.

    2016-04-01

    Regional climate predictions on timescales from one year to one decade are gaining importance since this time frame falls within the planning horizon of politics, economy, and society. In this context, decadal predictions are of particular interest for the development of renewable energies such as wind energy. The present study examines the decadal predictability of regional scale wind speed and wind energy potentials in the framework of the MiKlip consortium ("Mittelfristige Klimaprognosen"; www.fona-miklip.de). This consortium aims to develop a model system based on the Max-Planck-Institute Earth System Model (MPI-ESM) that can provide skilful decadal predictions on regional and global scales. Three generations of the decadal prediction system, which differ primarily in their ocean initialisation, are analysed here. Ensembles of uninitialised historical and yearly initialised hindcast experiments are used to assess different skill scores for 10m wind speeds and wind energy output (Eout) over Central Europe, with special focus given to Germany. With this aim, a statistical-dynamical downscaling (SDD) approach is used for the regionalisation of the global datasets. Its added value is evaluated by comparison of skill scores for MPI-ESM large-scale wind speeds and SDD simulated regional wind speeds. All three MPI-ESM ensemble generations show some forecast skill for annual mean wind speed and Eout over Central Europe on yearly and multi-yearly time scales. The forecast skill is mostly limited to the first years after initialisation. Differences between the three ensemble generations are generally small. The regionalisation preserves and sometimes increases the forecast skill of the global runs but results depend on lead time and ensemble generation. Moreover, regionalisation often improves the ensemble spread. Seasonal Eout skills are generally lower than for annual means. Skill scores are lowest during summer, and persist longest in autumn. A large-scale westerly

  13. Relationship Between Solar Wind Speed and Coronal Magnetic Field Properties

    CERN Document Server

    Fujiki, Ken'ichi; Iju, Tomoya; Hakamada, Kazuyuki; Kojima, Masayoshi

    2015-01-01

    We have studied the relationship between the solar-wind speed $[V]$ and the coronal magnetic-field properties (a flux expansion factor [$f$] and photospheric magnetic-field strength [$B_{\\mathrm{S}}$]) at all latitudes using data of interplanetary scintillation and solar magnetic field obtained for 24 years from 1986 to 2009. Using a cross-correlation analyses, we verified that $V$ is inversely proportional to $f$ and found that $V$ tends to increase with $B_{\\mathrm{S}}$ if $f$ is the same. As a consequence, we find that $V$ has extremely good linear correlation with $B_{\\mathrm{S}}/f$. However, this linear relation of $V$ and $B_{\\mathrm{S}}/f$ cannot be used for predicting the solar-wind velocity without information on the solar-wind mass flux. We discuss why the inverse relation between $V$ and $f$ has been successfully used for solar-wind velocity prediction, even though it does not explicitly include the mass flux and magnetic-field strength, which are important physical parameters for solar-wind accele...

  14. Sea surface wind speed estimation from space-based lidar measurements

    Directory of Open Access Journals (Sweden)

    Y. Hu

    2008-02-01

    Full Text Available Global satellite observations of lidar backscatter measurements acquired by the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO mission and collocated sea surface wind speed data from the Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E, are used to investigate the relation between wind driven wave slope variance and sea surface wind speed. The new slope variance – wind speed relation established from this study is similar to the linear relation from Cox-Munk (1954 and the log-linear relation from Wu (1972, 1990 for wind speed larger than 7 m/s and 13.3 m/s, respectively. For wind speed less than 7 m/s, the slope variance is proportional to the square root of the wind speed, assuming a two dimensional isotropic Gaussian wave slope distribution. This slope variance – wind speed relation becomes linear if a one dimensional Gaussian wave slope distribution is assumed. Contributions from whitecaps and subsurface backscattering are effectively removed by using 532 nm lidar depolarization measurements. This new slope variance – wind speed relation is used to derive sea surface wind speed from CALIPSO single shot lidar measurements (70 m spot size, after correcting for atmospheric attenuation. The CALIPSO wind speed result agrees with the collocated AMSR-E wind speed, with 1.2 m/s rms error.

  15. Operational-Condition-Independent Criteria Dedicated to Monitoring Wind Turbine Generators: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Yang, W.; Sheng, S.; Court, R.

    2012-08-01

    To date the existing wind turbine condition monitoring technologies and commercially available systems have not been fully accepted for improving wind turbine availability and reducing their operation and maintenance costs. One of the main reasons is that wind turbines are subject to constantly varying loads and operate at variable rotational speeds. As a consequence, the influences of turbine faults and the effects of varying load and speed are coupled together in wind turbine condition monitoring signals. So, there is an urgent need to either introduce some operational condition de-coupling procedures into the current wind turbine condition monitoring techniques or develop a new operational condition independent wind turbine condition monitoring technique to maintain high turbine availability and achieve the expected economic benefits from wind. The purpose of this paper is to develop such a technique. In the paper, three operational condition independent criteria are developed dedicated for monitoring the operation and health condition of wind turbine generators. All proposed criteria have been tested through both simulated and practical experiments. The experiments have shown that these criteria provide a solution for detecting both mechanical and electrical faults occurring in wind turbine generators.

  16. Relationship of oceanic whitecap coverage to wind speed and wind history

    NARCIS (Netherlands)

    Callaghan, A.; Leeuw, G. de; Cohen, L.; O'Dowd, C.D.

    2008-01-01

    Sea surface images obtained during the 2006 Marine Aerosol Production (MAP) campaign in the North East Atlantic were analysed for values of percentage whitecap coverage (W). Values of W are presented for wind speeds up to circa 23 m s-1. The W data were divided into two overlapping groups and a

  17. Flicker study on variable speed wind turbines with doubly fed induction generators

    DEFF Research Database (Denmark)

    Sun, Tao; Chen, Zhe; Blaabjerg, Frede

    2005-01-01

    Grid connected wind turbines may produce flicker during continuous operation. This paper presents a simulation model of a MW-level variable speed wind turbine with a doubly fed induction generator developed in the simulation tool of PSCAD/EMTDC. Flicker emission of variable speed wind turbines...... with doubly fed induction generators is investigated during continuous operation, and the dependence of flicker emission on mean wind speed, wind turbulence intensity, short circuit capacity of grid and grid impedance angle are analyzed. A comparison is done with the fixed speed wind turbine, which leads...... to a conclusion that the factors mentioned above have different influences on flicker emission compared with that in the case of the fixed speed wind turbine. Flicker mitigation is realized by output reactive power control of the variable speed wind turbine with doubly fed induction generator. Simulation results...

  18. Accounting for the speed shear in wind turbine power performance measurement

    DEFF Research Database (Denmark)

    Wagner, Rozenn

    in the power curve. A power curve defined in terms of this equivalent wind speed would be less dependant on the shear than the standard power curve. The equivalent wind speed method was then experimentally validated with lidar measurements. Two equivalent wind speed definitions were considered both resulting...... ways of accounting for the turbulence were tested with the experimental data: an adaptation of the equivalent wind speed so that it also accounts for the turbulence intensity and the combination of the equivalent wind speed accounting for the wind shear only with the turbulence normalising method...... the vertical wind shear and the turbulence intensity. The work presented in this thesis consists of the description and the investigation of a simple method to account for the wind speed shear in the power performance measurement. Ignoring this effect was shown to result in a power curve dependant on the shear...

  19. ACCUWIND - Accurate wind speed measurements in wind energy - Summary report[Cup and sonic anemometers

    Energy Technology Data Exchange (ETDEWEB)

    Friis Pedersen, T.; Dahlberg, J.Aa.; Cuerva, A.; Mouzakis, F.; Busche, P.; Eecen, P.; Sanz-Andres, A.; Franchini, S.; Markkilde Petersen, S.

    2006-07-15

    The cup anemometer is at present the standard instrument used for mean wind speed measurement in wind energy. It is being applied in high numbers around the world for wind energy assessments. It is also applied exclusively for accredited power performance measurements for certification and verification purposes, and for purposes of optimisation in research and development. The revised IEC standard on power performance measurements has now included requirements for classification of cup anemometers. The basis for setting up such requirements of cup anemometers is two EU projects SITEPARIDEN and CLASSCUP from which the proposed classification method for cup anemometers was developed for the IEC standard. While cup anemometers at present are the standard anemometer being used for average wind speed measurements, sonic anemometers have been developed significantly over the last years, and prices have come down. The application of sonic anemometers may increase in wind energy if they prove to have comparable or better operational characteristics compared to cup anemometers, and if similar requirements to sonic anemometers are established as for cup anemometers. Sonic anemometers have historically been used by meteorologists for turbulence measurements, but have also found a role on wind turbine nacelles for wind speed and yaw control purposes. The report on cup and sonic anemometry deals with establishment of robustness in assessment and classification by focus on methods and procedures for analysis of characteristics of cup and sonic anemometers. The methods and procedures provide a platform, hopefully for use in meeting the requirements of the IEC standard on power performance measurements, as well as for development of improved instruments. (au)

  20. Observing seasonal variations of sea surface wind speed and significant wave height using TOPEX altimetry

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    One year of ocean topography experiment (TOPEX) altimeter data are used to study the seasonal variations of global sea surface wind speed and significant wave height. The major wind and wave zones of the world oceans are precisely identified, their seasonal variability and characteristics are quantitatively analyzed, and the diversity of global wind speed seasonality and the variability of significant wave height in response to sea surface wind speed are also revealed.

  1. Analysis and Modelling of Extreme Wind Speed Distributions in Complex Mountainous Regions

    Science.gov (United States)

    Laib, Mohamed; Kanevski, Mikhail

    2016-04-01

    Modelling of wind speed distributions in complex mountainous regions is an important and challenging problem which interests many scientists from several fields. In the present research, high frequency (10 min) Swiss wind speed monitoring data (IDAWEB service, Meteosuisse) are analysed and modelled with different parametric distributions (Weibull, GEV, Gamma, etc.) using maximum likelihood method. In total, 111 stations placed in different geomorphological units and at different altitude (from 203 to 3580 meters) are studied. Then, this information is used for training machine learning algorithms (Extreme Learning Machines, Support vector machine) to predict the distribution at new places, potentially useful for aeolian energy generation. An important part of the research deals with the construction and application of a high dimensional input feature space, generated from digital elevation model. A comprehensive study was carried out using feature selection approach to get the best model for the prediction. The main results are presented as spatial patterns of distributions' parameters.

  2. Estimation of rotor effective wind speeds using autoregressive models on Lidar data

    Science.gov (United States)

    Giyanani, A.; Bierbooms, W. A. A. M.; van Bussel, G. J. W.

    2016-09-01

    Lidars have become increasingly useful for providing accurate wind speed measurements in front of the wind turbine. The wind field measured at distant meteorological masts changes its structure or was too distorted before it reaches the turbine. Thus, one cannot simply apply Taylor's frozen turbulence for representing this distant flow field at the rotor. Wind turbine controllers can optimize the energy output and reduce the loads significantly, if the wind speed estimates were known in advance with high accuracy and low uncertainty. The current method to derive wind speed estimations from aerodynamic torque, pitch angle and tip speed ratio after the wind field flows past the turbine and have their limitations, e.g. in predicting gusts. Therefore, an estimation model coupled with the measuring capability of nacelle based Lidars was necessary for detecting extreme events and for estimating accurate wind speeds at the rotor disc. Nacelle-mounted Lidars measure the oncoming wind field from utpo 400m(5D) in front of the turbine and appropriate models could be used for deriving the rotor effective wind speed from these measurements. This article proposes an auto-regressive model combined with a method to include the blockage factor in order to estimate the wind speeds accurately using Lidar measurements. An Armax model was used to determine the transfer function that models the physical evolution of wind towards the wind turbine, incorporating the effect of surface roughness, wind shear and wind variability at the site. The model could incorporate local as well as global effects and was able to predict the rotor effective wind speeds with adequate accuracy for wind turbine control actions. A high correlation of 0.86 was achieved as the Armax modelled signal was compared to a reference signal. The model could also be extended to estimate the damage potential during high wind speeds, gusts or abrupt change in wind directions, allowing the controller to act appropriately

  3. Influence of local wind speed and direction on wind power dynamics – Application to offshore very short-term forecasting

    DEFF Research Database (Denmark)

    Gallego, Cristobal; Pinson, Pierre; Madsen, Henrik

    2011-01-01

    Wind power time series usually show complex dynamics mainly due to non-linearities related to the wind physics and the power transformation process in wind farms. This article provides an approach to the incorporation of observed local variables (wind speed and direction) to model some of these e......Wind power time series usually show complex dynamics mainly due to non-linearities related to the wind physics and the power transformation process in wind farms. This article provides an approach to the incorporation of observed local variables (wind speed and direction) to model some...... of these effects by means of statistical models. To this end, a benchmarking between two different families of varyingcoefficient models (regime-switching and conditional parametric models) is carried out. The case of the offshore wind farm of Horns Rev in Denmark has been considered. The analysis is focused...... underlying effects in the dynamics of wind power time series....

  4. Spatial Patterns of Wind Speed Distributions in Switzerland

    CERN Document Server

    Laib, Mohamed

    2016-01-01

    This paper presents an initial exploration of high frequency records of extreme wind speed in two steps. The first consists in finding the suitable extreme distribution for $120$ measuring stations in Switzerland, by comparing three known distributions: Weibull, Gamma, and Generalized extreme value. This comparison serves as a basis for the second step which applies a spatial modelling by using Extreme Learning Machine. The aim is to model distribution parameters by employing a high dimensional input space of topographical information. The knowledge of probability distribution gives a comprehensive information and a global overview of wind phenomena. Through this study, a flexible and a simple modelling approach is presented, which can be generalized to almost extreme environmental data for risk assessment and to model renewable energy.

  5. 9x15 Low Speed Wind Tunnel Acoustic Improvements

    Science.gov (United States)

    Stark, David; Stephens, David

    2016-01-01

    The 9- by 15-Foot Low Speed Wind Tunnel (9x15 LSWT) at NASA Glenn Research Center was built in 1969 in the return leg of the 8- by 6-Foot Supersonic Wind Tunnel (8x6 SWT). The 8x6 SWT was completed in 1949 and acoustically treated to mitigate community noise issues in 1950. This treatment included the addition of a large muffler downstream of the 8x6 SWT test section and diffuser. The 9x15 LSWT was designed for performance testing of VSTOL aircraft models, but with the addition of the current acoustic treatment in 1986 the tunnel has been used principally for acoustic and performance testing of aircraft propulsions systems. The present document describes an anticipated acoustic upgrade to be completed in 2017.

  6. ARMA based approaches for forecasting the tuple of wind speed and direction

    Energy Technology Data Exchange (ETDEWEB)

    Erdem, Ergin; Shi, Jing [Department of Industrial and Manufacturing Engineering, North Dakota State University, Dept. 2485, PO Box 6050, Fargo, ND 58108 (United States)

    2011-04-15

    Short-term forecasting of wind speed and direction is of great importance to wind turbine operation and efficient energy harvesting. In this study, the forecasting of wind speed and direction tuple is performed. Four approaches based on autoregressive moving average (ARMA) method are employed for this purpose. The first approach features the decomposition of the wind speed into lateral and longitudinal components. Each component is represented by an ARMA model, and the results are combined to obtain the wind direction and speed forecasts. The second approach employs two independent ARMA models - a traditional ARMA model for predicting wind speed and a linked ARMA model for wind direction. The third approach features vector autoregression (VAR) models to forecast the tuple of wind attributes. The fourth approach involves employing a restricted version of the VAR approach to predict the same. By employing these four approaches, the hourly mean wind attributes are forecasted 1-h ahead for two wind observation sites in North Dakota, USA. The results are compared using the mean absolute error (MAE) as a measure for forecasting quality. It is found that the component model is better at predicting the wind direction than the traditional-linked ARMA model, whereas the opposite is observed for wind speed forecasting. Utilizing VAR approaches rather than the univariate counterparts brings modest improvement in wind direction prediction but not in wind speed prediction. Between restricted and unrestricted versions of VAR models, there is little difference in terms of forecasting performance. (author)

  7. Wind Speed Estimation and Wake model Re-calibration for Downregulated Offshore Wind Farms

    Science.gov (United States)

    Göçmen Bozkurt, Tuhfe; Giebel, Gregor; Kjølstad Poulsen, Niels; Réthoré, Pierre-Elouan; Mirzaei, Mahmood

    2014-05-01

    In recent years, the wind farm sizes have increased tremendously and with increasing installed capacity, the wind farms are requested to downregulate from their maximum possible power more frequently, especially in the offshore environment. Determination of the possible (or available) power is crucial not only because the reserve power has considerable market value but also for wind farm developers to be properly compensated for the loss during downregulation. While the available power calculation is straightforward for a single turbine, it gets rather complicated for the whole wind farm due to the change in the wake characteristics. In fact, the wake losses generated by the upstream turbine(s) decrease during downregulation and the downstream turbines therefore see more wind compared to the normal operation case. Currently, the Transmission System Operators (TSOs) have no real way to determine exactly the available power of a whole wind farm which is downregulated. Therefore, the PossPOW project aims to develop a verified and internationally accepted way to determine the possible power of a down-regulated offshore wind farm. The first phase of the project is to estimate the rotor effective wind speed. Since the nacelle anemometers are not readily available and are known to have reliability issues, the proposed method is to use power, pitch angle and rotational speed as inputs and combine it with a generic Cp model to estimate the wind speed. The performance of the model has been evaluated for both normal operation and downregulation periods using two different case studies: Horns Rev-I wind farm and NREL 5MW single turbine. During downregulation, the wake losses are not as severe and the velocity deficits at the downstream turbines are smaller as if also the wake is "downregulated". On the other hand, in order to calculate the available power, the wakes that would have been produced normally (if the turbines were not curtailed) are of importance, not the

  8. 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.

  9. LIDAR and SODAR Measurements of Wind Speed and Direction in Upland Terrain for Wind Energy Purposes

    Directory of Open Access Journals (Sweden)

    Eamon McKeogh

    2011-08-01

    Full Text Available Detailed knowledge of the wind resource is necessary in the developmental and operational stages of a wind farm site. As wind turbines continue to grow in size, masts for mounting cup anemometers—the accepted standard for resource assessment—have necessarily become much taller, and much more expensive. This limitation has driven the commercialization of two remote sensing (RS tools for the wind energy industry: The LIDAR and the SODAR, Doppler effect instruments using light and sound, respectively. They are ground-based and can work over hundreds of meters, sufficient for the tallest turbines in, or planned for, production. This study compares wind measurements from two commercial RS instruments against an instrumented mast, in upland (semi-complex terrain typical of where many wind farms are now being installed worldwide. With appropriate filtering, regression analyses suggest a good correlation between the RS instruments and mast instruments: The RS instruments generally recorded lower wind speeds than the cup anemometers, with the LIDAR more accurate and the SODAR more precise.

  10. Wind shear proportional errors in the horizontal wind speed sensed by focused, range gated lidars

    Science.gov (United States)

    Lindelöw, P.; Courtney, M.; Parmentier, R.; Cariou, J. P.

    2008-05-01

    The 10-minute average horizontal wind speeds sensed with lidar and mast mounted cup anemometers, at 60 to 116 meters altitude at HØvsØre, are compared. The lidar deviation from the cup value as a function of wind velocity and wind shear is studied in a 2-parametric regression analysis which reveals an altitude dependent relation between the lidar error and the wind shear. A likely explanation for this relation is an error in the intended sensing altitude. At most this error is estimated to 9 m which induced errors in the horizontal wind velocity of up to 0.5 m/s as compared to a cup at the intended altitude. The altitude errors of focused range gated lidars are likely to arise partly from an unaccounted shift of the weighting functions, describing the sample volume, due to the range dependent collection efficiency of the focused telescope. Possibilities of correcting the lidar measurements both for wind velocity and wind shear dependent errors are discussed. The 2-parametric regression analysis described in this paper is proven to be a better approach when acceptance testing and calibrating lidars.

  11. A design of vertical axis wind power generating system combined with Darrieus-Savonius for adaptation of variable wind speed

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Young Taek; Oh, Chul Soo [Kyung Pook National University, Taegu (Korea, Republic of)

    1996-02-01

    This paper presents a design of vertical axis Darrieus wind turbine combined with Savonius for wind-power generating system to be adapted for variable wind speed. The wind turbine consists of two troposkien- and four Savonius-blades. Darrieus turbine is designed with diameter 9.4[m], chord length 380[mm], tip speed ratio 5. Savonius turbine is designed with diameter 1.8[m], height 2[m], tip speed ratio 0.95. The design of turbine is laid for the main data of rated wind speed 10[m/s], turbine speed 101.4[rpm]. The generating power is estimated to maximum power 20[kWh], and this is converted to commercial power line by means of three phase synchronous generator-inverter system. Generating system is designed for operation on VSVF(variable speed variable frequency) condition and constant voltage system. (author). 11 refs., 14 figs.

  12. Wind Speed Forecasting Using Hybrid Wavelet Transform—ARMA Techniques

    Directory of Open Access Journals (Sweden)

    Diksha Kaur

    2015-01-01

    Full Text Available The objective of this paper is to develop a novel wind speed forecasting technique, which produces more accurate prediction. The Wavelet Transform (WT along with the Auto Regressive Moving Average (ARMA is chosen to form a hybrid whose combination is expected to give minimum Mean Absolute Prediction Error (MAPE. A simulation study has been conducted by comparing the forecasting results using the Wavelet-ARMA with the ARMA and Artificial Neural Network (ANN-Ensemble Kalman Filter (EnKF hybrid technique to verify the effectiveness of the proposed hybrid method. Results of the proposed hybrid show significant improvements in the forecasting error.

  13. Low Speed PSP Testing in Production Wind Tunnels

    Science.gov (United States)

    Bell, James; Mehta, Rabi; Schairer, Ed; Hand, Larry; Nixon, David (Technical Monitor)

    1998-01-01

    The brightness signal from a pressure-sensitive paint varies inversely with absolute pressure. Consequently high signal-to-noise ratios are required to resolve aerodynamic pressure fields at low speeds, where the pressure variation around an object might only be a few percent of the mean pressure. This requirement is unavoidable, and implies that care must be taken to minimize noise sources present in the measurement. This paper discusses and compares the main noise sources in low speed PSP testing using the "classical" intensity-based single-luminophore technique. These are: temperature variation, model deformation, and lamp drift/paint degradation. Minimization of these error sources from the point of view of operation in production wind tunnels is discussed, with some examples from recent tests in NASA Ames facilities.

  14. Soil tillage and windbreak effects on millet and cowpea: I. Wind speed, evaporation, and wind erosion

    Energy Technology Data Exchange (ETDEWEB)

    Banzhaf, J.; Leihner, D.E.; Buerkert, A. (Univ. of Hohenheim, Stuttgart (Germany)); Serafini, P.G. (Univ. of Arkansas, Fayetteville (United States))

    Deforestation, overgrazing, and declining soil regeneration periods have resulted in increased wind erosion problems in dry areas of the West African Sahel, but little is known about the bio-physical factors involved. This research was conducted to determine the effects of ridging and four different windbreak spacings on wind erosion, potential evaporation, and soil water reserves. A field trial was conducted from 1985 to 1987 on 12 ha of a Psammentic Paleustalf in Southern Niger. Millet, Pennisetum glaucum (L.), and cowpea, Vigna unguiculata (L.) Walp., were seeded in strips on flat and ridged soil. Windbreaks of savannah vegetation were spaced at 6, 20, 40, and 90 m. The effects of ridging on wind speed, evaporation, and wind erosion were small and mostly non-significant. However, average wind speed at 0.3 m above ground in the center of cowpea and millet strips was significantly reduced from 2.8 to 2.1 m s[sup [minus]1] as windbreak distances narrowed from 90 to 6 m. As a consequence, potential evaporation declined by 15% and the amount of windblown soil particles by 50% in ridged and by 70% in flat treatments. Despite reduced potential evaporation, average subsoil water reserves were 14 mm smaller in the 6- than in the 20-m windbreak spacing indicating excessive water extraction by the windbreak vegetation. Thus, establishing windbreaks with natural savannah vegetation may require a careful consideration of the agronomic benefits and costs to competing crops. 21 refs., 5 figs.

  15. Wind speed analysis in the province of Alicante, Spain. Potential for small-scale wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Cabello, M.; Orza, J.A.G. [SCOLAb, Fisica Aplicada, Universidad Miguel Hernandez, 03202 Elche (Spain)

    2010-12-15

    The statistical characteristics of the wind speed in the province of Alicante, southeastern Spain, have been analyzed using 9-year wind data recorded at 2 m above the ground by 17 weather stations belonging to the Valencian Institute for Agriculture Research (IVIA). The overall mean wind speed in the area is 1.7 m/s with the windy regions located at the northwest side in the highlands. A clear seasonal and daily pattern is shown with maximum in spring-summer during the central hours of the day, influenced by the sea breeze; and minimum in autumn-winter at night. The wind frequency distributions show two and three modes. The sum-lognormal model is found to be a good fit with very high correlation in all the sites. The extrapolation to 10 m with the power law and the wind shear exponent {alpha}, shows a large underestimation in the northern coastal sites and a good agreement in the innermost locations, when compared to measurements done at 10 m in a number of stations. (author)

  16. Power system integration and control of variable speed wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Eek, Jarle

    2009-12-15

    A wind power plant is a highly dynamic system that dependent on the type of technology requires a number of automatic control loops. This research deals with modelling, control and analysis related to power system integration of variable speed, pitch controlled wind turbines. All turbine components have been modelled and implemented in the power system simulation program SIMPOW, and a description of the modelling approach for each component is given. The level of model detail relates to the classical modelling of power system components for power system stability studies, where low frequency oscillations are of special importance. The wind turbine model includes a simplified representation of the developed rotor torque and the thrust force based on C{sub p-} and C{sub t} characteristic curves. The mechanical system model represents the fundamental torsional mode and the first mode of blades and tower movements. Two generator technologies have been investigated. The doubly fed induction generator (DFIG) and the stator converter interfaced permanent magnet synchronous generator (PMSG). A simplified model of a 2 level voltage source converter is used for both machine types. The generator converter controllers have been given special attention. All model components are linearized for the purpose of control system design and power system interaction related to small signal stability analysis. Different control strategies discussed in the literature have been investigated with regard to power system interaction aspects. All control parameters are identified using the internal model control approach. The analysis is focused on three main areas: 1. Identification of low damped oscillatory modes. This is carried out by the establishment and discussion of wind turbine modelling. 2. Interaction between control loops. A systematic approach is presented in order to analyse the influence of control loops used in variable speed wind turbines. 3.Impact on power system performance

  17. Accounting for the speed shear in wind turbine power performance measurement

    DEFF Research Database (Denmark)

    Wagner, Rozenn; Courtney, Michael; Gottschall, Julia

    2011-01-01

    The current IEC standard for wind turbine power performance measurement only requires measurement of the wind speed at hub height assuming this wind speed to be representative for the whole rotor swept area. However, the power output of a wind turbine depends on the kinetic energy flux, which...... itself depends on the wind speed profile, especially for large turbines. Therefore, it is important to characterize the wind profile in front of the turbine, and this should be preferably achieved by measuring the wind speed over the vertical range between lower and higher rotor tips. In this paper, we...... describe an experiment in which wind speed profiles were measured in front of a multimegawatt turbine using a ground–based pulsed lidar. Ignoring the vertical shear was shown to overestimate the kinetic energy flux of these profiles, in particular for those deviating significantly from a power law profile...

  18. Effective wind speed estimation: Comparison between Kalman Filter and Takagi-Sugeno observer techniques.

    Science.gov (United States)

    Gauterin, Eckhard; Kammerer, Philipp; Kühn, Martin; Schulte, Horst

    2016-05-01

    Advanced model-based control of wind turbines requires knowledge of the states and the wind speed. This paper benchmarks a nonlinear Takagi-Sugeno observer for wind speed estimation with enhanced Kalman Filter techniques: The performance and robustness towards model-structure uncertainties of the Takagi-Sugeno observer, a Linear, Extended and Unscented Kalman Filter are assessed. Hence the Takagi-Sugeno observer and enhanced Kalman Filter techniques are compared based on reduced-order models of a reference wind turbine with different modelling details. The objective is the systematic comparison with different design assumptions and requirements and the numerical evaluation of the reconstruction quality of the wind speed. Exemplified by a feedforward loop employing the reconstructed wind speed, the benefit of wind speed estimation within wind turbine control is illustrated.

  19. Coupling between SST and wind speed over mesoscale eddies in the South China Sea

    Science.gov (United States)

    Sun, Shuangwen; Fang, Yue; Liu, Baochao; ᅟ, Tana

    2016-11-01

    The coupling between sea surface temperature (SST) and sea surface wind speed over mesoscale eddies in the South China Sea (SCS) was studied using satellite measurements. Positive correlations between SST anomalies (SSTA) and wind speed anomalies were found over both cyclonic and anticyclonic eddies. In contrast to the open oceans, the spatial patterns of the coupling over mesoscale eddies in the SCS depend largely on the seasonal variations of the background SST gradient, wind speed, and wind directional steadiness. In summer, the maximum SSTA location coincides with the center of eddy-induced sea surface height anomalies. In winter, the eddy-induced SSTA show a clear dipole pattern. The spatial patterns of wind speed anomalies over eddies are similar to those of the SSTA in both seasons. Wind speed anomalies are linearly correlated with SSTA over anticyclonic and cyclonic eddies. The coupling coefficients between SSTA and wind speed anomalies in the SCS are comparable to those in the open oceans.

  20. Comparison of measured and simulated wind speed data in the North Atlantic

    Energy Technology Data Exchange (ETDEWEB)

    Winterfeldt, J. [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Kuestenforschung

    2008-11-06

    A systematic investigation and comparison of near-surface marine wind speed obtained from in situ and satellite observations, atmospheric reanalyses and regional atmospheric hindcasts with reanalysis driven regional climate models (RCMs) is presented for the eastern North Atlantic and the North Sea. Wind speed retrievals from two remote sensing data sets, namely QuikSCAT and the Hamburg Ocean Atmosphere Parameters and Fluxes from Satellite (HOAPS) data set, are found to give good representation of observed near-surface wind speed. The value of the root mean squared error (RMSE) for all co-located HOAPS and in situ wind speed data is 2 m/s, while it is 1.8 m/s for QuikSCAT demonstrating that QuikSCAT's mission requirement of providing wind speed with an RMSE of 2 m/s is met for the eastern North Atlantic and the North Sea. QuikSCAT shows a slightly better agreement with observed instantaneous wind speed and its frequency distribution than HOAPS. In contrast, HOAPS wind speed is available for a much longer period and is therefore the more suitable product for climatic studies or investigations of trends in wind speed. The capability of two state-of-the-art RCMs (with and without spectral nudging applied) to add value for surface marine wind fields in comparison to the reanalysis wind speed forcing is assessed by the comparison with in situ wind speed observations in the eastern North Atlantic in 1998. The comparison of the 10 m wind speed forecasts from the NCEP/NCAR and NCEP/DOE-II reanalyses with in-situ observations demonstrates the implausibility of the latter forecast resulting in its non-consideration in the added value assessment. The added value is investigated for instantaneous wind speeds (relevant for case studies) and their frequency distribution (relevant for e.g., extreme value statistics and estimations of wind potential). The observations are discriminated into groups according to their proximity to land and assimilation status, meaning whether

  1. Universal computer vision system for monitoring the main parameters of wind turbines

    Directory of Open Access Journals (Sweden)

    Korzhavin Sergey

    2016-01-01

    Full Text Available The article presents universal autonomous system of computer vision to monitor the operation of wind turbines. The proposed system allows to estimate the rotational speed and the relative position deviation of the wind turbine. We present a universal method for determining the rotation of wind turbines of various shapes and structures. All obtained data are saved in the database. The presented method was tested at the Territory of Non-traditional Renewable Energy Sources of Ural Federal University Experimental wind turbines is produced by “Scientific and Production Association of automatics named after academician N.A. Semikhatov”. Results show the efficiency of the proposed system and the ability to determine main parameters such as the rotational speed, accuracy and quickness of orientation. The proposed solution is to assume that, in most cases a rotating and central parts of the wind turbine can be allocated different color. The color change of wind blade should not affect the system performance.

  2. Overall control strategy of variable speed doubly-fed induction generator wind turbine

    DEFF Research Database (Denmark)

    Hansen, A. D.; Soerensen, P.; Iov, Florin

    2004-01-01

    The variable speed doubly-fed induction generator wind turbine is today the most widely used concept. The paper presents an overall control system of the variable speed DFIG wind turbine, with focus on the control strategies and algorithms applied at each hierarchical control level of the wind tu...

  3. Vertical Structure of the Wind Speed Profile at the North Sea Offshore Measurement Platform FINO1

    Science.gov (United States)

    Kettle, A. J.

    2013-12-01

    The vertical wind speed profile in the lowest 100m of the marine atmospheric boundary layer has been characterized from data collected at the FINO1 offshore research platform in the German North Sea sector for 2005. Located in 30m of water, the platform has a dense vertical array of meteorological instrumentation to measure wind speed, air temperature, relative humidity, and atmospheric turbulence characteristics. Along measurements of the ocean temperature and surface waves, the platform is well-equipped to characterize wind properties in the near-surface boundary layer. Preliminary analysis reveals a high incidence of vertical wind speed profiles that deviate significantly from Monin-Obukhov similarity theory with wind speed inflections that suggest decoupled layers near the surface. The presentation shows how the properties of the vertical wind speed profile change mainly depending on the wind speed, wind direction, and time of year. The results are significant because there are few reports of inflections in the vertical wind speed profile over the ocean and there is an a priori assumption that the vertical wind speed profile varies smoothly according to similarity theory. There are possible consequences for the wind energy development in terms of understanding the forces acting on offshore wind turbines whose rotors sweep across heights 150-200m above the sea surface.

  4. Simulation of Variable Speed Wind Generation System Using Boost Converter of Permanent Magnet Synchronous Generator

    Science.gov (United States)

    Ohyama, Kazuhiro; Sakamoto, Tsuyoshi; Arinaga, Shinji; Yamashita, Yukio

    This paper proposes variable-speed wind generation system using the boost converter. The proposed system has three speed control modes for the wind velocity. The control mode of low wind velocity regulates the armature current of the generator with the boost converter to control the speed of wind turbine. The control mode of middle wind velocity regulates the DC link voltage with the vector controlled inverter to control the speed of wind turbine. The control mode of high wind velocity regulates the pitch angle of the wind turbine with the pitch angle control system to control the speed of wind turbine. The hybrid of three control modes extends the variable-speed range. The proposed system simplifies the maintenance and improves the reliability and reduces the cost in compare with the variable-speed wind generation system using PWM converter. This paper describes the control strategy and modeling for simulation using Matlab Simulink of the proposed system. Also this paper describes the control strategy and modeling of variable-speed wind generation system using PWM converter. The steady state and transient responses for wind velocity changes are simulated using the Matlab Simulink. This paper verifies the fundamental performance of the system using boost converter by discussing the simulation results of the both systems.

  5. Flying with the wind: scale dependency of speed and direction measurements in modelling wind support in avian flight

    Science.gov (United States)

    Safi, Kamran; Kranstauber, Bart; Weinzierl, Rolf P.; Griffin, Larry; Reese, Eileen C.; Cabot, David; Cruz, Sebastian; Proaño, Carolina; Takekawa, John Y.; Newman, Scott H.; Waldenström, Jonas; Bengtsson, Daniel; Kays, Roland; Wikelski, Martin; Bohrer, Gil

    2013-01-01

    Background: Understanding how environmental conditions, especially wind, influence birds' flight speeds is a prerequisite for understanding many important aspects of bird flight, including optimal migration strategies, navigation, and compensation for wind drift. Recent developments in tracking technology and the increased availability of data on large-scale weather patterns have made it possible to use path annotation to link the location of animals to environmental conditions such as wind speed and direction. However, there are various measures available for describing not only wind conditions but also the bird's flight direction and ground speed, and it is unclear which is best for determining the amount of wind support (the length of the wind vector in a bird’s flight direction) and the influence of cross-winds (the length of the wind vector perpendicular to a bird’s direction) throughout a bird's journey. Results: We compared relationships between cross-wind, wind support and bird movements, using path annotation derived from two different global weather reanalysis datasets and three different measures of direction and speed calculation for 288 individuals of nine bird species. Wind was a strong predictor of bird ground speed, explaining 10-66% of the variance, depending on species. Models using data from different weather sources gave qualitatively similar results; however, determining flight direction and speed from successive locations, even at short (15 min intervals), was inferior to using instantaneous GPS-based measures of speed and direction. Use of successive location data significantly underestimated the birds' ground and airspeed, and also resulted in mistaken associations between cross-winds, wind support, and their interactive effects, in relation to the birds' onward flight. Conclusions: Wind has strong effects on bird flight, and combining GPS technology with path annotation of weather variables allows us to quantify these effects for

  6. Experimental investigation of the dependence of radar backscattering on wind speed, wind stress and wave height

    Science.gov (United States)

    Gogineni, S. P.; Katsaros, K. B.

    1989-01-01

    During summer 1988, radar measurements were performed in conjunction with detailed environmental observations on Lake Washington at the University of Washington Sand Point field station. Radar data were collected at 5.3 and 10 GHz for incidence angles between 30 and 60 deg with VV-polarization. The environmental measurements included wind speed and direction, large-wave heights, the high-frequency portion of the wave spectrum, humidity, and air and water temperatures. The small-scale wave spectrum was measured using a resistance wire gauge. The results show that backscatter increased with wind speed as expected. However, little difference was observed in the scattering coefficient for upwind and crosswind directions. The results also indicated an increase in the amplitude of small waves with friction velocity.

  7. Analyzing Effects of Turbulence on Power Generation Using Wind Plant Monitoring Data: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, J.; Chowdhury, S.; Hodge, B. M.

    2014-01-01

    In this paper, a methodology is developed to analyze how ambient and wake turbulence affects the power generation of a single wind turbine within an array of turbines. Using monitoring data from a wind power plant, we selected two sets of wind and power data for turbines on the edge of the wind plant that resemble (i) an out-of-wake scenario (i.e., when the turbine directly faces incoming winds) and (ii) an in-wake scenario (i.e., when the turbine is under the wake of other turbines). For each set of data, two surrogate models were then developed to represent the turbine power generation (i) as a function of the wind speed; and (ii) as a function of the wind speed and turbulence intensity. Support vector regression was adopted for the development of the surrogate models. Three types of uncertainties in the turbine power generation were also investigated: (i) the uncertainty in power generation with respect to the published/reported power curve, (ii) the uncertainty in power generation with respect to the estimated power response that accounts for only mean wind speed; and (iii) the uncertainty in power generation with respect to the estimated power response that accounts for both mean wind speed and turbulence intensity. Results show that (i) under the same wind conditions, the turbine generates different power between the in-wake and out-of-wake scenarios, (ii) a turbine generally produces more power under the in-wake scenario than under the out-of-wake scenario, (iii) the power generation is sensitive to turbulence intensity even when the wind speed is greater than the turbine rated speed, and (iv) there is relatively more uncertainty in the power generation under the in-wake scenario than under the out-of-wake scenario.

  8. Optimal application of climate data to the development of design wind speeds

    DEFF Research Database (Denmark)

    Kruger, Andries C.; Retief, Johan V.; Goliger, Adam M.;

    2014-01-01

    Accurate extreme wind statistics are important for the design of a safe and economic built environment. The recent revision of the South African Wind Loading Code for engineers (SANS 10160-3:2011) will also include a reassessment of design wind speed statistics. In addition, the Wind Atlas of Sou...

  9. Control of variable speed wind turbines with doubly-fed induction generators

    DEFF Research Database (Denmark)

    Hansen, A. D.; Soerensen, Poul; Iov, Florin;

    2004-01-01

    The paper presents an overall control method for variable speed pitch controlled wind turbines with double-feed induction generators (DFIG). Emphasis is on control strategies and algorithms applied at each hierarchical control level of the wind turbine. The objectives of the control system are: 1......) to control the power drawn from the wind turbine in order to track the wind turbine maximum power operation point, 2) to limit the power in case of large wind speeds, and 3) to control the reactive power interchanged between the wind turbine generator and the grid. The present control method is designed...... for normal continuous operations. The strongest feature of the implemented control method is that it allows the turbine to operate with the optimum power efficiency over a wider range of wind speeds. The model of the variable speed, variable pitch wind turbine with doubly-fed induction generator...

  10. Modelling and control of variable speed wind turbines for power system studies

    DEFF Research Database (Denmark)

    Michalke, Gabriele; Hansen, Anca Daniela

    2010-01-01

    Modern wind turbines are predominantly variable speed wind turbines with power electronic interface. Emphasis in this paper is therefore on the modelling and control issues of these wind turbine concepts and especially on their impact on the power system. The models and control are developed...... and implemented in the power system simulation tool DIgSILENT. Important issues like the fault ride-through and grid support capabilities of these wind turbine concepts are addressed. The paper reveals that advanced control of variable speed wind turbines can improve power system stability. Finally......, it will be shown in the paper that wind parks consisting of variable speed wind turbines can help nearby connected fixed speed wind turbines to ride-through grid faults. Copyright © 2009 John Wiley & Sons, Ltd....

  11. An Appropriate Wind Model for Wind Integrated Power Systems Reliability Evaluation Considering Wind Speed Correlations

    OpenAIRE

    Rajesh Karki; Dinesh Dhungana; Roy Billinton

    2013-01-01

    Adverse environmental impacts of carbon emissions are causing increasing concerns to the general public throughout the world. Electric energy generation from conventional energy sources is considered to be a major contributor to these harmful emissions. High emphasis is therefore being given to green alternatives of energy, such as wind and solar. Wind energy is being perceived as a promising alternative. This source of energy technology and its applications have undergone significant researc...

  12. Voltage sag influence on fatigue life of the drivetrain of fixed speed wind turbines

    DEFF Research Database (Denmark)

    Veluri, Badrinath; Santos-Martin, David; Jensen, Henrik Myhre

    2011-01-01

    on the fatigue life of important drivetrain components. The high penetration of wind energy in the electrical grids demands new requirements for the operation of wind energy conversion systems. Although fixed speed wind turbine technology is nowadays replaced by variable speed wind turbines. In some countries...... effect on the fatigue life of drivetrain components. The capability to simulate these phenomena is a novel aspect in the present effort....

  13. Low Wind Speed Turbine Developments in Convoloid Gearing: Final Technical Report, June 2005 - October 2008

    Energy Technology Data Exchange (ETDEWEB)

    Genesis Partners LP

    2010-08-01

    This report presents the results of a study conducted by Genesis Partners LP as part of the United States Department of Energy Wind Energy Research Program to develop wind technology that will enable wind systems to compete in regions having low wind speeds. The purpose of the program is to reduce the cost of electricity from large wind systems in areas having Class 4 winds to 3 cents per kWh for onshore systems or 5 cents per kWh for offshore systems. This work builds upon previous activities under the WindPACT project, the Next Generation Turbine project, and Phase I of the Low Wind Speed Turbine (LWST) project. This project is concerned with the development of more cost-effective gearing for speed increasers for wind turbines.

  14. A preliminary assessment of the sea surface wind speed production of HY-2 scanning microwave radiometer

    Institute of Scientific and Technical Information of China (English)

    HUANG Xiaoqi; ZHU Jianhua; LIN Mingsen; ZHAO Yili; WANG He; CHEN Chuntao; PENG Hailong; ZHANG Youguang

    2014-01-01

    A scanning microwave radiometer (RM) was launched on August 16, 2011, on board HY-2 satellite. The six-month long global sea surface wind speeds observed by the HY-2 scanning microwave radiometer are preliminarily validated using in-situ measurements and WindSat observations, respectively, from January to June 2012. The wind speed root-mean-square (RMS) difference of the comparisons with in-situ data is 1.89 m/s for the measurements of NDBC and 1.72 m/s for the recent four-month data measured by PY30-1 oil platform, respectively. On a global scale, the wind speeds of HY-2 RM are compared with the sea surface wind speeds derived from WindSat, the RMS difference of 1.85 m/s for HY-2 RM collocated observations data set is calculated in the same period as above. With analyzing the global map of a mean difference between HY-2 RM and WindSat, it appears that the bias of the sea surface wind speed is obviously higher in the inshore regions. In the open sea, there is a relatively higher positive bias in the mid-latitude regions due to the overestimation of wind speed observations, while the wind speeds are underestimated in the Southern Ocean by HY-2 RM relative to WindSat observations.

  15. A Statistical Model for the Prediction of Wind-Speed Probabilities in the Atmospheric Surface Layer

    Science.gov (United States)

    Efthimiou, G. C.; Hertwig, D.; Andronopoulos, S.; Bartzis, J. G.; Coceal, O.

    2016-11-01

    Wind fields in the atmospheric surface layer (ASL) are highly three-dimensional and characterized by strong spatial and temporal variability. For various applications such as wind-comfort assessments and structural design, an understanding of potentially hazardous wind extremes is important. Statistical models are designed to facilitate conclusions about the occurrence probability of wind speeds based on the knowledge of low-order flow statistics. Being particularly interested in the upper tail regions we show that the statistical behaviour of near-surface wind speeds is adequately represented by the Beta distribution. By using the properties of the Beta probability density function in combination with a model for estimating extreme values based on readily available turbulence statistics, it is demonstrated that this novel modelling approach reliably predicts the upper margins of encountered wind speeds. The model's basic parameter is derived from three substantially different calibrating datasets of flow in the ASL originating from boundary-layer wind-tunnel measurements and direct numerical simulation. Evaluating the model based on independent field observations of near-surface wind speeds shows a high level of agreement between the statistically modelled horizontal wind speeds and measurements. The results show that, based on knowledge of only a few simple flow statistics (mean wind speed, wind-speed fluctuations and integral time scales), the occurrence probability of velocity magnitudes at arbitrary flow locations in the ASL can be estimated with a high degree of confidence.

  16. Trends in 100m Wind Speed using Global High-Resolution Downscaled Analysis

    Science.gov (United States)

    McGraw, Z.

    2015-12-01

    The strength and variability of the wind energy resource are expected to be susceptible to the complex changes undergoing Earth's climate system. A variety of physical mechanisms for long-term wind speed changes has been proposed, including modified temperature gradients, shifting storm tracks and altered land use. This study is an analysis of multi-decadal wind speed trends within a high-resolution downscaled global analysis provided by our collaborators at Vestas Wind Systems A/S. We have sought to identify the regions and landscape types that most exhibit long-term changes to wind speed and identify the mechanisms responsible.

  17. A Hybrid Wavelet Transform Based Short-Term Wind Speed Forecasting Approach

    OpenAIRE

    Jujie Wang

    2014-01-01

    It is important to improve the accuracy of wind speed forecasting for wind parks management and wind power utilization. In this paper, a novel hybrid approach known as WTT-TNN is proposed for wind speed forecasting. In the first step of the approach, a wavelet transform technique (WTT) is used to decompose wind speed into an approximate scale and several detailed scales. In the second step, a two-hidden-layer neural network (TNN) is used to predict both approximated scale and detailed scales,...

  18. Time series models to simulate and forecast hourly averaged wind speeds in Quetta, Pakistan

    Energy Technology Data Exchange (ETDEWEB)

    Lalarukh Kamal [Balochistan University, Quetta (Pakistan). Dept. of Mathematics; Yasmin Zahra Jafri [Balochistan University, Quetta (Pakistan). Dept. of Statistics

    1997-07-01

    Stochastic simulation and forecast models of hourly average wind speeds are presented. Time series models take into account several basic features of wind speed data including autocorrelation, non-Gaussian distribution and diurnal nonstationarity. The positive correlation between consecutive wind speed observations is taken into account by fitting an ARMA (p,q) process to wind speed data transformed to make their distribution approximately Gaussian and standardized to remove scattering of transformed data. Diurnal variations have been taken into account to observe forecasts and its dependence on lead times. We find the ARMA (p,q) model suitable for prediction intervals and probability forecasts. (author)

  19. Cauchy-Matern Model of Sea Surface Wind Speed at the Lake Worth, Florida

    Directory of Open Access Journals (Sweden)

    Ming Li

    2012-01-01

    Full Text Available We study the Cauchy-Matern (CM process with long-range dependence (LRD. The closed form of its power spectrum density (PSD function is given. We apply it to model the autocovariance function (ACF and the PSD of the sea surface wind speed (wind speed for short observed in the Lake Worth, Florida, over the 1984–2006 period. The present results exhibit that the wind speed at the Lake Worth over 1984–2006 is of LRD. The present results exhibit that the CM process may yet be a novel model to fit the wind speed there.

  20. Chaos and periodicity in solar wind speed: cycle 23

    Science.gov (United States)

    Sarkar, Tushnik; Ray, Rajdeep; Khondekar, Mofazzal H.; Ghosh, Koushik; Banerjee, Subrata

    2015-06-01

    The solar wind speed time series data from 1st January, 1997 to 28th October, 2003 has been pre-processed using simple exponential smoothing, discrete wavelet transform for denoising to investigate the underneath dynamics of it. Recurrence plot and recurrence quantification analysis has revealed that the time series is non-stationary one with deterministic chaotic behavior. The Hilbert-Huang Transform has been used in search of the underlying periods of the data series. Present investigation has revealed the periods of 21 days, 32.5 days, 43.6 days, 148.86 days, 180.7 days, 355.5 days, 403.2 days, 413.6 days, 490.72 days, 729.6 days, 1086.76 days, 1599.4 days and 1892.6 days.

  1. Prediction of Typhoon Wind Speeds under Global Warming Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Choun, Young Sun; Kim, Min Kyu [KAERI, Daejeon (Korea, Republic of); Kang, Ju Whan; Kim, Yang Seon [Mokpo National University, Muan (Korea, Republic of)

    2016-05-15

    The continuous increase of SST by global warming conditions in the western North Pacific Ocean results in an increased occurrence of supertyphoons in East Asia and the Korean Peninsula. Recent numerical experiments have found that the central pressures of two historical typhoons, Maemi (2003) and Rusa (2002), which recorded the highest storm surges along the coasts of the Korean Peninsula, dropped about 19 and 17 hPa, respectively, when considering the future SST (a warming of 3.9 .deg. C for 100 years) over the East China Sea. The maximum wind speeds increase under global warming conditions. The probability of occurrence of super-typhoons increases in the future. The estimated return period for supertyphoons affecting the Younggwang site is about 1,000,000 years.

  2. Changes in Surface Wind Speed over North America from CMIP5 Model Projections and Implications for Wind Energy

    Directory of Open Access Journals (Sweden)

    Sujay Kulkarni

    2014-01-01

    Full Text Available The centennial trends in the surface wind speed over North America are deduced from global climate model simulations in the Climate Model Intercomparison Project—Phase 5 (CMIP5 archive. Using the 21st century simulations under the RCP 8.5 scenario of greenhouse gas emissions, 5–10 percent increases per century in the 10 m wind speed are found over Central and East-Central United States, the Californian Coast, and the South and East Coasts of the USA in winter. In summer, climate models projected decreases in the wind speed ranging from 5 to 10 percent per century over the same coastal regions. These projected changes in the surface wind speed are moderate and imply that the current estimate of wind power potential for North America based on present-day climatology will not be significantly changed by the greenhouse gas forcing in the coming decades.

  3. A Meteorological Information Mining-Based Wind Speed Model for Adequacy Assessment of Power Systems With Wind Power

    DEFF Research Database (Denmark)

    Guo, Yifei; Gao, Houlei; Wu, Qiuwei

    2017-01-01

    factors are calculated. Secondly, the meteorological data are classified into several states using an improved Fuzzy C-means (FCM) algorithm. Then the Markov chain is used to model the chronological characteristics of meteorological states and wind speed. The proposed model was proved to be more accurate......Accurate wind speed simulation is an essential prerequisite to analyze the power systems with wind power. A wind speed model considering meteorological conditions and seasonal variations is proposed in this paper. Firstly, using the path analysis method, the influence weights of meteorological...... in capturing the characteristics of probability distribution, auto-correlation and seasonal variations of wind speed compared with the traditional Markov chain Monte Carlo (MCMC) and autoregressive moving average (ARMA) model. Furthermore, the proposed model was applied to adequacy assessment of generation...

  4. Wind Turbine Drivetrain Condition Monitoring - An Overview (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Sheng, S.; Yang, W.

    2013-07-01

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

  5. Structural health monitoring of wind turbine blades

    Science.gov (United States)

    Rumsey, Mark A.; Paquette, Joshua A.

    2008-03-01

    As electric utility wind turbines increase in size, and correspondingly, increase in initial capital investment cost, there is an increasing need to monitor the health of the structure. Acquiring an early indication of structural or mechanical problems allows operators to better plan for maintenance, possibly operate the machine in a de-rated condition rather than taking the unit off-line, or in the case of an emergency, shut the machine down to avoid further damage. This paper describes several promising structural health monitoring (SHM) techniques that were recently exercised during a fatigue test of a 9 meter glass-epoxy and carbon-epoxy wind turbine blade. The SHM systems were implemented by teams from NASA Kennedy Space Center, Purdue University and Virginia Tech. A commercial off-the-shelf acoustic emission (AE) NDT system gathered blade AE data throughout the test. At a fatigue load cycle rate around 1.2 Hertz, and after more than 4,000,000 fatigue cycles, the blade was diagnostically and visibly failing at the out-board blade spar-cap termination point at 4.5 meters. For safety reasons, the test was stopped just before the blade completely failed. This paper provides an overview of the SHM and NDT system setups and some current test results.

  6. Individual Pitch Control for Mitigation of Power Fluctuation of Variable Speed Wind Turbines

    DEFF Research Database (Denmark)

    Zhang, Yunqian; Hu, Weihao; Chen, Zhe;

    2012-01-01

    Grid connected wind turbines are the sources of power fluctuations during continuous operation due to wind speed variation, wind shear and tower shadow effects. This paper presents an individual pitch control (IPC) strategy to mitigate the wind turbine power fluctuation at both above and below...... the rated wind speed conditions. Three pitch angles are adjusted separately according to the generator output power and the azimuth angle of the wind turbine. The IPC strategy scheme is proposed and the individual pitch controller is designed. The simulations are performed on the NREL (National Renewable...

  7. Fixed-speed active-stall wind turbines in offshore applications

    DEFF Research Database (Denmark)

    Akhmatov, Vladislav; Nielsen, Arne Hejde

    2005-01-01

    A large offshore wind farm in the East Danish power system was commissioned in 2003 at Rodsand. The power capacity of the wind farm is 165 MW divided between 72 wind turbines. For this large offshore application, robust and well-known wind technology has been chosen in the form of fixed-speed, ac......-speed, active-stall wind turbines equipped with induction generators. In this paper, maintaining and improving the short-term voltage stability is discussed and systematized in terms of this wind technology. Copyright (C) 2004 John Wiley Sons, Ltd....

  8. Park correction for FINO1-wind speed measurements at alpha ventus

    Energy Technology Data Exchange (ETDEWEB)

    Kinder, F.; Westerhellweg, A.; Neumann, T. [DEWI, Wilhelmshaven (Germany)

    2013-02-15

    The FINO1-research platform and its 100m-mast were erected in 2003 to perform investigations of the marine atmospheric boundary layer for offshore wind energy projects. Meteorological measurements focus on wind speed and wind direction measured at different heights [1]. After six years of undisturbed measurements between 2004 and 2009, the offshore wind farm alpha ventus influences the wind and turbulence conditions reaching FINO1 from eastern directions. In the wake of a wind turbine the flow is changed such that the turbulence intensity increases while the wind speed decreases. To continue free flow measurements from eastern directions a LiDAR-device was mounted on the alpha ventus converter station in April 2011. The LiDAR measurements are evaluated in comparison with data from FINO1 for the recovery of the undisturbed wind field at FINO1 and to develop a park correction for the FINO1-wind measurement. For the period of May 2011 to September 2012 the park factor (vLiDAR/vFINO1) for eastern directions is calculated from 10-minute mean values and then averaged for 2 -wind direction bins, 2 m/s-wind speed bins and three different stability classes for four heights respectively. Only data points were regarded during which all the wind turbines influencing the particular wind direction bin were operating. The park effect increases for lower wind speeds and for heights close to the nacelle with highest values occurring during stable atmospheric stratification. (orig.)

  9. Intelligent control for large-scale variable speed variable pitch wind turbines

    Institute of Scientific and Technical Information of China (English)

    Xinfang ZHANG; Daping XU; Yibing LIU

    2004-01-01

    Large-scale wind turbine generator systems have strong nonlinear multivariable characteristics with many uncertain factors and disturbances.Automatic control is crucial for the efficiency and reliability of wind turbines.On the basis of simplified and proper model of variable speed variable pitch wind turbines,the effective wind speed is estimated using extended Kalman filter.Intelligent control schemes proposed in the paper include two loops which operate in synchronism with each other.At below-rated wind speed,the inner loop adopts adaptive fuzzy control based on variable universe for generator torque regulation to realize maximum wind energy capture.At above-rated wind speed, a controller based on least square support vector machine is proposed to adjust pitch angle and keep rated output power.The simulation shows the effectiveness of the intelligent control.

  10. Direct Torque Control of a Small Wind Turbine with a Sliding-Mode Speed Controller

    Science.gov (United States)

    Sri Lal Senanayaka, Jagath; Karimi, Hamid Reza; Robbersmyr, Kjell G.

    2016-09-01

    In this paper. the method of direct torque control in the presence of a sliding-mode speed controller is proposed for a small wind turbine being used in water heating applications. This concept and control system design can be expanded to grid connected or off-grid applications. Direct torque control of electrical machines has shown several advantages including very fast dynamics torque control over field-oriented control. Moreover. the torque and flux controllers in the direct torque control algorithms are based on hvsteretic controllers which are nonlinear. In the presence of a sliding-mode speed control. a nonlinear control system can be constructed which is matched for AC/DC conversion of the converter that gives fast responses with low overshoots. The main control objectives of the proposed small wind turbine can be maximum power point tracking and soft-stall power control. This small wind turbine consists of permanent magnet synchronous generator and external wind speed. and rotor speed measurements are not required for the system. However. a sensor is needed to detect the rated wind speed overpass events to activate proper speed references for the wind turbine. Based on the low-cost design requirement of small wind turbines. an available wind speed sensor can be modified. or a new sensor can be designed to get the required measurement. The simulation results will be provided to illustrate the excellent performance of the closed-loop control system in entire wind speed range (4-25 m/s).

  11. A conceptual framework for evaluating variable speed generator options for wind energy applications

    Science.gov (United States)

    Reddoch, T. W.; Lipo, T. A.; Hinrichsen, E. N.; Hudson, T. L.; Thomas, R. J.

    1995-01-01

    Interest in variable speed generating technology has accelerated as greater emphasis on overall efficiency and superior dynamic and control properties in wind-electric generating systems are sought. This paper reviews variable speed technology options providing advantages and disadvantages of each. Furthermore, the dynamic properties of variable speed systems are contrasted with synchronous operation. Finally, control properties of variable speed systems are examined.

  12. Field Measurement of Wind Speeds and Wind-Induced Responses atop the Shanghai World Financial Center under Normal Climate Conditions

    Directory of Open Access Journals (Sweden)

    Yong Quan

    2013-01-01

    Full Text Available Field measurement data on wind velocities and wind-induced acceleration responses at the top of the 492 m high Shanghai World Financial Center (SWFC under normal climate conditions are studied. Characteristics of the mean wind speeds and turbulence intensities, gust factors, power spectral densities, and turbulence integral scales of the fluctuating wind speed are analyzed in different observation time intervals. Power spectral densities of wind-induced acceleration are also investigated. The basic natural frequencies and structural damping ratios of the building are identified based on Hilbert-Huang transform method and random decrement method. The field measurement results of wind-induced responses of the SWFC are finally compared with those from the corresponding high-frequency force balance wind tunnel test study.

  13. The Skipheia Wind Measurement Station. Instrumentation, Wind Speed Profiles and Turbulence Spectra

    Energy Technology Data Exchange (ETDEWEB)

    Aasen, S.E.

    1995-10-01

    This thesis describes the design of a measurement station for turbulent wind and presents results from an analysis of the collected data. The station is located at Skipheia near the south-west end of Froeya, an island off the coast of Mid-Norway. The station is unique for studies of turbulent winds because of the large numbers of sensors, which are located at various heights above ground up to 100 m, a sampling rate of 0.85 Hz and storage of the complete time series. The frequency of lightning and atmospheric discharges to the masts are quite high and much effort has gone into minimizing the damage caused by lightning activity. A major part of the thesis deals with data analysis and modelling. There are detailed discussions on the various types of wind sensors and their calibration, the data acquisition system and operating experiences with it, the database, data quality control, the wind speed profile and turbulence. 40 refs., 78 figs., 17 tabs.

  14. Numerical study on the restriction speed of train passing curved rail in cross wind

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The results of numerical investigations of aerodynamic forces and moment coefficients of flow passing a simplified train geometry under different wind speeds are summarized. To compute numerically the different coefficients, the three-dimensional Reynolds-Averaged Navier-Stokes (RANS) equations, combined with the k-ε turbulence model, were solved using finite volume technique. The pres-sure-velocity fields were coupled using the SIMPLE algorithm. At each iteration the pressure correction was obtained by solving a velocity divergence-derived Poisson-like equation. With the computed aerodynamic forces, the formula of the restriction speed at which the train passed curved rail in cross wind was deduced to analyse the influences of aerodynamic forces on the restriction speed. Results of numerical investigations showed that aerodynamic lift and overturn moment increased more and more rapidly with train speed and wind speed. The enhancement trends showed nonlinear phenomena and enhanced risk in the course of train movement. When the train travels at a high speed and encounters a huge cross wind, the influence involved by nonlinear risk increment will extremely impair safety of train. The following conclusion can also be drawn: The effect of aerodynamic lift makes restriction speed reduce, however, the influences of aerodynamic drag to the limit train speed rest on the direction of wind flow. When the wind blows from inner rail to outer rail, aerodynamic forces shall reduce the restriction speed, by contraries, when the wind blows from outer rail to inner rail, aerodynamic forces shall increase the restriction speed.

  15. Numerical study on the restriction speed of train passing curved rail in cross wind

    Institute of Scientific and Technical Information of China (English)

    CHEN RuiLin; ZENG QingYuan; ZHONG XinGu; XIANG Jun; GUO XiaoGang; ZHAO Gang

    2009-01-01

    The results of numerical investigations of aerodynamic forces and moment coefficients of flow passing a simplified train geometry under different wind speeds are summarized. To compute numerically the different coefficients, the three-dimensional Reynolds-Averaged Navier-Stokes (RANS) equations,combined with the k-ε turbulence model, were solved using finite volume technique. The pressure-velocity fields were coupled using the SIMPLE algorithm. At each iteration the pressure correction was obtained by solving a velocity divergence-derived Poisson-Iike equation. With the computed aerodynamic forces, the formula of the restriction speed at which the train passed curved rail in cross wind was deduced to analyse the influences of aerodynamic forces on the restriction speed. Results of numerical investigations showed that aerodynamic lift and overturn moment increased more and more rapidly with train speed and wind speed. The enhancement trends showed nonlinear phenomena and enhanced risk in the course of train movement. When the train travels at a high speed and encounters a huge cross wind, the influence involved by nonlinear risk increment will extremely impair safety of train.The following conclusion can also he drawn: The effect of aerodynamic lift makes restriction speed reduce, however, the influences of aerodynamic drag to the limit train speed rest on the direction of wind flow. When the wind blows from inner rail to outer rail, aerodynamic forces shall reduce the restriction speed, by contraries, when the wind blows from outer rail to inner rail, aerodynamic forces shall increase the restriction speed.

  16. Analysis of wind speed distributions: Wind distribution function derived from minimum cross entropy principles as better alternative to Weibull function

    Energy Technology Data Exchange (ETDEWEB)

    Kantar, Yeliz Mert; Usta, Ilhan [Department of Statistics, Anadolu University, Eskisehir 26470 (Turkey)

    2008-05-15

    In this study, the minimum cross entropy (MinxEnt) principle is applied for the first time to the wind energy field. This principle allows the inclusion of previous information of a wind speed distribution and covers the maximum entropy (MaxEnt) principle, which is also discussed by Li and Li and Ramirez as special cases in their wind power study. The MinxEnt probability density function (pdf) derived from the MinxEnt principle are used to determine the diurnal, monthly, seasonal and annual wind speed distributions. A comparison between MinxEnt pdfs defined on the basis of the MinxEnt principle and the Weibull pdf on wind speed data, which are taken from different sources and measured in various regions, is conducted. The wind power densities of the considered regions obtained from Weibull and MinxEnt pdfs are also compared. The results indicate that the pdfs derived from the MinxEnt principle fit better to a variety of measured wind speed data than the conventionally applied empirical Weibull pdf. Therefore, it is shown that the MinxEnt principle can be used as an alternative method to estimate both wind distribution and wind power accurately. (author)

  17. Wind speed analysis in La Vainest, Mexico: a bimodal probability distribution case

    Energy Technology Data Exchange (ETDEWEB)

    Jaramillo, O.A.; Borja, M.A. [Energias No Convencionales, Morelos (Mexico). Instituto de Investigaciones Electricas

    2004-08-01

    The statistical characteristics of the wind speed in La Vainest, Oxoic, Mexico, have been analyzed by using wind speed data recorded by Instituto de Investigaciones Electricas (IIE). By grouping the observations by annual, seasonal and wind direction, we show that the wind speed distribution, with calms included, is not represented by the typical two-parameter Weibull function. A mathematical formulation by using a bimodal Weibull and Weibull probability distribution function (PDF) has been developed to analyse the wind speed frequency distribution in that region. The model developed here can be applied for similar regions where the wind speed distribution presents a bimodal PDF. The two-parameter Weibull wind speed distribution must not be generalised, since it is not accurate to represent some wind regimes as the case of La Ventosa, Mexico. The analysis of wind data shows that computing the capacity factor for wind power plants to be installed in La Ventosa must be carded out by means of a bimodal PDF instead of the typical Weibull PDF. Otherwise, the capacity factor will be underestimated. (author)

  18. Generation and Validation of Spatial Distribution of Hourly Wind Speed Time-Series using Machine Learning

    Science.gov (United States)

    Veronesi, F.; Grassi, S.

    2016-09-01

    Wind resource assessment is a key aspect of wind farm planning since it allows to estimate the long term electricity production. Moreover, wind speed time-series at high resolution are helpful to estimate the temporal changes of the electricity generation and indispensable to design stand-alone systems, which are affected by the mismatch of supply and demand. In this work, we present a new generalized statistical methodology to generate the spatial distribution of wind speed time-series, using Switzerland as a case study. This research is based upon a machine learning model and demonstrates that statistical wind resource assessment can successfully be used for estimating wind speed time-series. In fact, this method is able to obtain reliable wind speed estimates and propagate all the sources of uncertainty (from the measurements to the mapping process) in an efficient way, i.e. minimizing computational time and load. This allows not only an accurate estimation, but the creation of precise confidence intervals to map the stochasticity of the wind resource for a particular site. The validation shows that machine learning can minimize the bias of the wind speed hourly estimates. Moreover, for each mapped location this method delivers not only the mean wind speed, but also its confidence interval, which are crucial data for planners.

  19. Hour-Ahead Wind Speed and Power Forecasting Using Empirical Mode Decomposition

    Directory of Open Access Journals (Sweden)

    Ying-Yi Hong

    2013-11-01

    Full Text Available Operation of wind power generation in a large farm is quite challenging in a smart grid owing to uncertain weather conditions. Consequently, operators must accurately forecast wind speed/power in the dispatch center to carry out unit commitment, real power scheduling and economic dispatch. This work presents a novel method based on the integration of empirical mode decomposition (EMD with artificial neural networks (ANN to forecast the short-term (1 h ahead wind speed/power. First, significant parameters for training the ANN are identified using the correlation coefficients. These significant parameters serve as inputs of the ANN. Owing to the volatile and intermittent wind speed/power, the historical time series of wind speed/power is decomposed into several intrinsic mode functions (IMFs and a residual function through EMD. Each IMF becomes less volatile and therefore increases the accuracy of the neural network. The final forecasting results are achieved by aggregating all individual forecasting results from all IMFs and their corresponding residual functions. Real data related to the wind speed and wind power measured at a wind-turbine generator in Taiwan are used for simulation. The wind speed forecasting and wind power forecasting for the four seasons are studied. Comparative studies between the proposed method and traditional methods (i.e., artificial neural network without EMD, autoregressive integrated moving average (ARIMA, and persistence method are also introduced.

  20. An Experimental Investigation of FNN Model for Wind Speed Forecasting Using EEMD and CS

    Directory of Open Access Journals (Sweden)

    Jianzhou Wang

    2015-01-01

    Full Text Available With depletion of traditional energy and increasing environmental problems, wind energy, as an alternative renewable energy, has drawn more and more attention internationally. Meanwhile, wind is plentiful, clean, and environmentally friendly; moreover, its speed is a very important piece of information needed in the operations and planning of the wind power system. Therefore, choosing an effective forecasting model with good performance plays a quite significant role in wind power system. A hybrid CS-EEMD-FNN model is firstly proposed in this paper for multistep ahead prediction of wind speed, in which EEMD is employed as a data-cleaning method that aims to remove the high frequency noise embedded in the wind speed series. CS optimization algorithm is used to select the best parameters in the FNN model. In order to evaluate the effectiveness and performance of the proposed hybrid model, three other short-term wind speed forecasting models, namely, FNN model, EEMD-FNN model, and CS-FNN model, are carried out to forecast wind speed using data measured at a typical site in Shandong wind farm, China, over three seasons in 2011. Experimental results demonstrate that the developed hybrid CS-EEMD-FNN model outperforms other models with more accuracy, which is suitable to wind speed forecasting in this area.

  1. Retrieving hurricane wind speeds using cross-polarization C-band measurements

    NARCIS (Netherlands)

    Van Zadelhoff, G.J.; Stoffelen, A.; Vachon, P.W.; Wolfe, J.; Horstmann, J.; Belmonte Rivas, M.

    2014-01-01

    Hurricane-force wind speeds can have a large societal impact and in this paper microwave C-band cross-polarized (VH) signals are investigated to assess if they can be used to derive extreme wind-speed conditions. European satellite scatterometers have excellent hurricane penetration capability at C-

  2. DAC with LQR Control Design for Pitch Regulated Variable Speed Wind Turbine

    DEFF Research Database (Denmark)

    Imran, Raja Muhammad; Hussain, Dil Muhammad Akbar; Soltani, Mohsen

    2014-01-01

    Disturbance Accommodation Control (DAC) is used to model and simulate a system with known disturbance waveform. This paper presents a control scheme to mitigate the effect of disturbances by using collective pitch control for the aboverated wind speed (Region III) for a variable speed wind turbin...

  3. Retrieving hurricane wind speeds using cross-polarization C-band measurements

    NARCIS (Netherlands)

    Van Zadelhoff, G.J.; Stoffelen, A.; Vachon, P.W.; Wolfe, J.; Horstmann, J.; Belmonte Rivas, M.

    2014-01-01

    Hurricane-force wind speeds can have a large societal impact and in this paper microwave C-band cross-polarized (VH) signals are investigated to assess if they can be used to derive extreme wind-speed conditions. European satellite scatterometers have excellent hurricane penetration capability at C-

  4. Retrieving hurricane wind speeds using cross-polarization C-band measurements

    NARCIS (Netherlands)

    Van Zadelhoff, G.J.; Stoffelen, A.; Vachon, P.W.; Wolfe, J.; Horstmann, J.; Belmonte Rivas, M.

    2014-01-01

    Hurricane-force wind speeds can have a large societal impact and in this paper microwave C-band cross-polarized (VH) signals are investigated to assess if they can be used to derive extreme wind-speed conditions. European satellite scatterometers have excellent hurricane penetration capability at

  5. Estimated changes in wind speed and wind power density over the western High Plains, 1971-2000

    Science.gov (United States)

    Greene, J. Scott; Chatelain, Matthew; Morrissey, Mark; Stadler, Steve

    2012-08-01

    This manuscript presents the results of research on the temporal patterns in wind speed and wind power density from 1971 to 2000. The study area is across the western High Plains states east of the Rocky Mountains in an area which has a proven wind power resource. Policies and economic analyses involving the rapidly expanding wind power industry have often assumed a constant in the wind resource; however, any temporal pattern or trend in wind speeds can have a meaningful impact on the reliability of wind power as an energy resource. Using data provided by the North American Regional Climate Change Assessment Program (NARCCAP) to analyze decadal and seasonal trends of wind data, this study shows that from 1971 to 2000 there were some notable changes in the NARCCAP simulated wind velocities over the study region. Wind speed trends across the central High Plains of the USA were most notable across the western portion of the study area along the higher terrain near the front range of the Rocky Mountains. The most significant changes occurred during winter and spring when a large portion of the study area experienced the most substantial decrease in wind speed, with a 20% reduction in wind power density during spring across the western portion of the study area. During summer and fall, the trends are less noticeable, with only very small changes in the summer. Fall was the only season that saw widespread increased values of wind power density from the 1970s to 1990s, with increases of nearly 10% in some southern areas of the study area. Based upon the analysis of the data and previous literature, it is theorized that these changes could be the result of changing synoptic patterns across the study region.

  6. Wireless Sensors for Wind Turbine Blades Monitoring

    Science.gov (United States)

    Iftimie, N.; Steigmann, R.; Danila, N. A.; Rosu, D.; Barsanescu, P. D.; Savin, A.

    2017-06-01

    The most common defects in turbine blades may be faulty microscopic and mesoscopic appeared in matrix, no detected by classical nondestructive testing (i.e. using phased array sensors), broken fibers can also appear and develop under moderated loads, or cracks and delaminations due to low energy impacts, etc. The paper propose to present the results obtained from testing of glass fiber reinforced plastic used in the construction of the wind turbine blades as well as the monitoring of the entire scalable blade using wireless sensors placed on critical location on blade. In order to monitories the strain/stress during the tests, the determination of the location and the nature of defects have been simulated using FEM.

  7. MPPT Algorithm for Small Wind Systems based on Speed Control Strategy

    Directory of Open Access Journals (Sweden)

    Ciprian VLAD

    2008-07-01

    Full Text Available This paper presents experimental results of an autonomous low-power wind energy conversion system (WECS, based on a permanent-magnet synchronous generator (PMSG connected directly to the wind turbine. The purpose of this paper is to present an improving method for MPPT (Maximum Power Point Tracking algorithm based shaft rotational speed optimal control. The proposed method concern the variable delay compensation between measured wind speed from anemometer and wind shaft rotational speed proportional signal. Experimental results aiming to prove the efficiency of the proposed method are presented.

  8. Relationship between wind speed and aerosol optical depth over remote ocean

    Directory of Open Access Journals (Sweden)

    R. G. Grainger

    2009-11-01

    Full Text Available The effect of wind speed on aerosol optical depth (AOD at 550 nm over remote ocean regions is investigated. Remote ocean regions are defined by the combination of AOD from satellite observation and wind direction from ECMWF. According to our definition, many oceanic regions cannot be taken as remote ocean regions due to long-range transportation of aerosols from continents. Highly correlated linear relationships are found in remote ocean regions with a wind speed range of 4–20 ms−1. The enhancement of AOD at high wind speed is explained as the increase of sea salt aerosol production.

  9. Nonparametric Stochastic Model for Uncertainty Quantifi cation of Short-term Wind Speed Forecasts

    Science.gov (United States)

    AL-Shehhi, A. M.; Chaouch, M.; Ouarda, T.

    2014-12-01

    Wind energy is increasing in importance as a renewable energy source due to its potential role in reducing carbon emissions. It is a safe, clean, and inexhaustible source of energy. The amount of wind energy generated by wind turbines is closely related to the wind speed. Wind speed forecasting plays a vital role in the wind energy sector in terms of wind turbine optimal operation, wind energy dispatch and scheduling, efficient energy harvesting etc. It is also considered during planning, design, and assessment of any proposed wind project. Therefore, accurate prediction of wind speed carries a particular importance and plays significant roles in the wind industry. Many methods have been proposed in the literature for short-term wind speed forecasting. These methods are usually based on modeling historical fixed time intervals of the wind speed data and using it for future prediction. The methods mainly include statistical models such as ARMA, ARIMA model, physical models for instance numerical weather prediction and artificial Intelligence techniques for example support vector machine and neural networks. In this paper, we are interested in estimating hourly wind speed measures in United Arab Emirates (UAE). More precisely, we predict hourly wind speed using a nonparametric kernel estimation of the regression and volatility functions pertaining to nonlinear autoregressive model with ARCH model, which includes unknown nonlinear regression function and volatility function already discussed in the literature. The unknown nonlinear regression function describe the dependence between the value of the wind speed at time t and its historical data at time t -1, t - 2, … , t - d. This function plays a key role to predict hourly wind speed process. The volatility function, i.e., the conditional variance given the past, measures the risk associated to this prediction. Since the regression and the volatility functions are supposed to be unknown, they are estimated using

  10. The Forecasting Procedure for Long-Term Wind Speed in the Zhangye Area

    Directory of Open Access Journals (Sweden)

    Zhenhai Guo

    2010-01-01

    Full Text Available Energy crisis has made it urgent to find alternative energy sources for sustainable energy supply; wind energy is one of the attractive alternatives. Within a wind energy system, the wind speed is one key parameter; accurately forecasting of wind speed can minimize the scheduling errors and in turn increase the reliability of the electric power grid and reduce the power market ancillary service costs. This paper proposes a new hybrid model for long-term wind speed forecasting based on the first definite season index method and the Autoregressive Moving Average (ARMA models or the Generalized Autoregressive Conditional Heteroskedasticity (GARCH forecasting models. The forecasting errors are analyzed and compared with the ones obtained from the ARMA, GARCH model, and Support Vector Machine (SVM; the simulation process and results show that the developed method is simple and quite efficient for daily average wind speed forecasting of Hexi Corridor in China.

  11. Generation of Random Wind Speed Profiles for Evaluation of Stress in WT Power Converters

    DEFF Research Database (Denmark)

    Pigazo, Alberto; Qin, Zian; Liserre, Marco;

    2013-01-01

    changes depending on the real wind speed once the wind turbine is operating. Usually, the real wind speed profiles are employed to evaluate this stress but they do not consider all possible operation conditions and require intensive computations. To solve these issues, this paper proposes the generation......Wind turbines are subjected to wind speed variations that cause a power profile that will stress the overall system. This stress is tranfered to the power converter, resulting in temperature variations of the power devices and, hence, causing the reduction of the lifetime. The lifetime expectation...... of random wind speed profiles, based on the measured ones, in order to evaluate the thermal stress of the power devices based on a simplified statistical approach....

  12. The detection of wind turbine shaft misalignment using temperature monitoring.

    OpenAIRE

    2016-01-01

    Temperature is a parameter increasingly monitored in wind turbine systems. This paper details a potential temperature monitoring technique for use on shaft couplings. Such condition monitoring methods aid fault detection in other areas of wind turbines. However, application to shaft couplings has not previously been widely researched. A novel temperature measurement technique is outlined, using an infra-red thermometer which can be applied to online condition monitoring. The method was va...

  13. Improved Spatio-Temporal Linear Models for Very Short-Term Wind Speed Forecasting

    Directory of Open Access Journals (Sweden)

    Tansu Filik

    2016-03-01

    Full Text Available In this paper, the spatio-temporal (multi-channel linear models, which use temporal and the neighbouring wind speed measurements around the target location, for the best short-term wind speed forecasting are investigated. Multi-channel autoregressive moving average (MARMA models are formulated in matrix form and efficient linear prediction coefficient estimation techniques are first used and revised. It is shown in detail how to apply these MARMA models to the spatially distributed wind speed measurements. The proposed MARMA models are tested using real wind speed measurements which are collected from the five stations around Canakkale region of Turkey. According to the test results, considerable improvements are observed over the well known persistence, autoregressive (AR and multi-channel/vector autoregressive (VAR models. It is also shown that the model can predict wind speed very fast (in milliseconds which is suitable for the immediate short-term forecasting.

  14. Rain-aerosol relationships influenced by wind speed: RAIN-AEROSOL RELATIONSHIPS

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Yang [Scripps Institution of Oceanography, University of California, San Diego, La Jolla California USA; Russell, Lynn M. [Scripps Institution of Oceanography, University of California, San Diego, La Jolla California USA; Lou, Sijia [Scripps Institution of Oceanography, University of California, San Diego, La Jolla California USA; Liu, Ying [Atmospheric Science and Global Change Division, Pacific Northwest National Laboratory, Richland Washington USA; Singh, Balwinder [Atmospheric Science and Global Change Division, Pacific Northwest National Laboratory, Richland Washington USA; Ghan, Steven J. [Atmospheric Science and Global Change Division, Pacific Northwest National Laboratory, Richland Washington USA

    2016-03-08

    The aerosol optical depth (AOD) has been shown to correlate with precipitation rate (R) in recent studies. The relationships between R and AOD are examined in this study using 150-year simulations in preindustrial conditions with the CESM model. Through partial correlation analysis, with the impact from 10-m wind speed removed, relationships between modeled AOD and R exert a significant change from positive to negative over the mid-latitude oceans, indicating that the wind speed has the largest contribution to the relationships over the mid-latitude oceans. Sensitivity simulation shows that variations in wind speed lead to increasing R by +0.99 mm day-1 averaged globally, offsetting 64% of the wet scavenging induced decrease in precipitation between polluted and clean conditions. These demonstrate that wind speed is one of the major drivers of R-AOD relationships. Relative humidity can also result in the positive relationships; however, its role is smaller than that of wind speed.

  15. Reduction of horizontal wind speed in a boundary layer with obstacles

    DEFF Research Database (Denmark)

    Emeis, S.; Frandsen, S.

    1993-01-01

    The reduction of horizontal wind speed at hub height in an infinite cluster of wind turbines is computed from a balance between a loss of horizontal momentum due to the drag and replenishment from above by turbulent fluxes. This reduction is derived without assumptions concerning the vertical wind...

  16. Offshore coastal wind speed gradients: Issues for the design and development of large offshore windfarms

    DEFF Research Database (Denmark)

    Barthelmie, R.J.; Badger, Jake; Pryor, S.C.

    2007-01-01

    Simulations, from mesoscale numerical models, and analyses of in-situ and remote sensing data from offshore wind farms in Denmark, are used to examine both horizontal and vertical gradients of wind speeds in the coastal zone. Results suggest that the distance from the coastline over which wind...

  17. INTELLIGENT TOOL CONDITION MONITORING IN HIGH-SPEED ...

    African Journals Online (AJOL)

    MR PRINCE

    work model has been developed for on-line condition monitoring of tool wear in high-speed ... degraded behaviours in wire electrical dis- ... mathematical models such as regression (Lin et ... an 11 kW Computer Numerical Controlled.

  18. Directional Profiles of Wind Speed and Turbulence Intensity over Forest and Open Land

    Science.gov (United States)

    Beyer, Elisabeth; Dietz, Sebastian; Pinter, Anna

    2014-05-01

    More and more wind turbines are built onshore and reduce the available areas for wind energy. Forests are additional potential for wind energy priority areas. But the high roughness of wooden areas and the resulting turbulences make it difficult to assess sites in forests. In order to cope with this problem some measurements were done inside and outside wooden areas. Therefore met masts equipped with ultra sonic and cup anemometers and LIDAR were used. With the measured wind speed and its standard deviation the turbulence intensity was calculated. The results are direction dependent profiles of wind speed and turbulence intensity.

  19. The Control System Simulation of Variable-Speed Constant-Frequency Wind Turbine

    Institute of Scientific and Technical Information of China (English)

    窦金延; 曹娜

    2010-01-01

    <正>In general,Variable-Speed Constant Frequency (VSCF)Wind generation system is controlled by stator voltage orientation method which based on the mathematic model of VSCF Wind generation system and discussed the control strategy.Present the whole dynamic control model of variable-speed wind generator system in MATLAB/ Simulink,and the simulation results confirm the validity and effectiveness of the proposed control strategy.

  20. Changes in Wind Speed and Extremes in Beijing during 1960-2008 Based on Homogenized Observations

    Institute of Scientific and Technical Information of China (English)

    LI Zhen; YAN Zhongwei; TU Kai; LIU Weidong; WANG Yingchun

    2011-01-01

    Daily observations of wind speed at 12 stations in the Greater Beijing Area during 1960-2008 were homogenized using the Multiple Analysis of Series for Homogenization method. The linear trends in the regional mean annual and seasonal (winter, spring, summer and autumn) wind speed series were -0.26,-0.39, -0.30, -0.12 and -0.22 m s-1 (10 yr)-1, respectively. Winter showed the greatest magnitude in declining wind speed, followed by spring, autumn and summer. The annual and seasonal frequencies of wind speed extremes (days) also decreased, more prominently for winter than for the other seasons. The declining trends in wind speed and extremes were formed mainly by some rapid declines during the 1970s and 1980s. The maximum declining trend in wind speed occurred at Chaoyang (CY), a station within the central business district (CBD) of Beijing with the highest level of urbanization. The declining trends were in general smaller in magnitude away from the city center, except for the winter case in which the maximum declining trend shifted northeastward to rural Miyun (MY). The influence of urbanization on the annual wind speed was estimated to be about -0.05 m s-1 (10 yr)-1 during 1960-2008, accounting for around one fifth of the regional mean declining trend. The annual and seasonal geostrophic wind speeds around Beijing, based on daily mean sea level pressure (MSLP) from the ERA-40 reanalysis dataset, also exhibited decreasing trends, coincident with the results from site observations. A comparative analysis of the MSLP fields between 1966-1975 and 1992-2001 suggested that the influences of both the winter and summer monsoons on Beijing were weaker in the more recent of the two decades. It is suggested that the bulk of wind in Beijing is influenced considerably by urbanization, while changes in strong winds or wind speed extremes are prone to large-scale climate change in the region.

  1. Monitoring fatigue loads on wind turbines using cycle counting data acquisition systems

    Energy Technology Data Exchange (ETDEWEB)

    Soeker, H.; Seifert, H. [Deutsches Windenergie-Institut (Germany); Fragoulis, A.; Vionis, P.; Foussekis, D. [Center for Renewable Energy Sources (Greece); Dahlberg, J.A.; Poppen, M. [The Aeronautical Research Institue of Sweden (Sweden)

    1996-09-01

    As in any industrial application, the duration of a wind turbine`s life is a key parameter for the evaluation of its economic potential. Assuming a service life of 20 years, components of the turbine have to withstand a number of load cycles of up to 10{sup 8}. Such numbers of load cycles impose high demands on the fatigue characteristics of both, the used materials and the design. Nevertheless, fatigue loading of wind turbine components still remains a parameter of high uncertainty in the design of wind turbines. The specific features of these fatigue loads can be expected to vary with the type of turbine and the site of operation. In order to ensure the reliability of the next generation of larger scale wind turbines improved load assumptions will be of vital importance. Within the scope of the presented research program DEWI, C.R.E.S. and FFA monitored fatigue loads of serial produced wind turbines by means of a monitoring method that uses on-line cycle counting techniques. The blade root bending moments of two pitch controlled, variable speed wind turbines operating in the Hamswehrum wind farm, and also that of a stall controlled, fixed speed wind turbine operating in CRES` complex terrain test site, were measured by DEWI and CRES. In parallel FFA used their database of time series measurements of blade root bending moments on a stall controlled, fixed speed turbine at Alsvik Windfarm in order to derive semi-empirical fatigue load data. The experience gained from application of the on-line measurement technique is discussed with respect to performance, data quality, reliability and cost effectiveness. Investigations on the effects of wind farm and complex terrain operation on the fatigue loads of wind turbine rotor blades are presented. (au)

  2. Bayesian adaptive combination of short-term wind speed forecasts from neural network models

    Energy Technology Data Exchange (ETDEWEB)

    Li, Gong; Shi, Jing; Zhou, Junyi [Department of Industrial and Manufacturing Engineering, North Dakota State University, Dept. 2485, PO Box 6050, Fargo, ND 58108 (United States)

    2011-01-15

    Short-term wind speed forecasting is of great importance for wind farm operations and the integration of wind energy into the power grid system. Adaptive and reliable methods and techniques of wind speed forecasts are urgently needed in view of the stochastic nature of wind resource varying from time to time and from site to site. This paper presents a robust two-step methodology for accurate wind speed forecasting based on Bayesian combination algorithm, and three neural network models, namely, adaptive linear element network (ADALINE), backpropagation (BP) network, and radial basis function (RBF) network. The hourly average wind speed data from two North Dakota sites are used to demonstrate the effectiveness of the proposed approach. The results indicate that, while the performances of the neural networks are not consistent in forecasting 1-h-ahead wind speed for the two sites or under different evaluation metrics, the Bayesian combination method can always provide adaptive, reliable and comparatively accurate forecast results. The proposed methodology provides a unified approach to tackle the challenging model selection issue in wind speed forecasting. (author)

  3. The Change in the Maximum Wind Speed and the Impact of it on Agricultural Production

    Institute of Scientific and Technical Information of China (English)

    WU Jian-mei; SUN Jin-sen; SUI Gui-ling; XIE Su-he; WANG Meng

    2012-01-01

    Using the data on the maximum wind speed within ten minutes every month in the period 1971-2009 in Zhucheng City of Shandong Province, we conduct statistical analysis of the maximum wind speed in Zhucheng City. The results show that over thirty-nine years, the annual maximum wind speed in four seasons in Zhucheng City tends to decline. The annual maximum wind speed declines at the rate of 1.45 m/s every 10 years. It falls fastest in winter, with decline rate of 1.73 m/s every 10 years; it is close to the average annual maximum wind speed in spring and autumn, with decline rate of 1.44 m/s and 14.8 m/s every 10 years, respectively; it falls slowest in summer, and the extreme value of the maximum wind speed occurs mainly in spring. The curve of changes in the monthly maximum wind speed in Zhucheng City assumes diminishing shape of "two peaks and one trough". We conduct preliminary analysis of the windy weather situation, and put forth specific defensive measures against the hazards of strong winds in the different periods.

  4. Proactive condition monitoring of low-speed machines

    CERN Document Server

    Stamboliska, Zhaklina; Moczko, Przemyslaw

    2015-01-01

    This book broadens readers’ understanding of proactive condition monitoring of low-speed machines in heavy industries. It focuses on why low-speed machines are different than others and how maintenance of these machines should be implemented with particular attention. The authors explain the best available monitoring techniques for various equipment and the principle of how to get proactive information from each technique. They further put forward possible strategies for application of FEM for detection of faults and technical assessment of machinery. Implementation phases are described and industrial case-studies of proactive condition monitoring are included. Proactive Condition Monitoring of Low-Speed Machines is an essential resource for engineers and technical managers across a range of industries as well as design engineers working in industrial product development. This book also: ·         Explains the practice of proactive condition monitoring and illustrates implementation phases ·   ...

  5. Exogenous Measurements from Basic Meteorological Stations for Wind Speed Forecasting

    Directory of Open Access Journals (Sweden)

    Antonio Moreno-Muñoz

    2013-11-01

    Full Text Available This research presents a comparative analysis of wind speed forecasting methods applied to perform 1 h-ahead forecasting. The main significant development has been the introduction of low-quality measurements as exogenous information to improve these predictions. Eight prediction models have been assessed; three of these models [persistence, autoregressive integrated moving average (ARIMA and multiple linear regression] are used as references, and the remaining five, based on neural networks, are evaluated on the basis of two procedures. Firstly, four quality indices are assessed (the Pearson’s correlation coefficient, the index of agreement, the mean absolute error and the mean squared error. Secondly, an analysis of variance test and multiple comparison procedure are conducted. The findings indicate that a backpropagation network with five neurons in the hidden layer is the best model obtained with respect to the reference models. The pair of improvements (mean absolute-mean squared error obtained are 29.10%–56.54%, 28.15%–53.99% and 4.93%–14.38%, for the persistence, ARIMA and multiple linear regression models, respectively. The experimental results reported in this paper show that traditional agricultural measurements enhance the predictions.

  6. Validation of sentinel-1A SAR coastal wind speeds against scanning LiDAR

    DEFF Research Database (Denmark)

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

    2017-01-01

    High-accuracy wind data for coastal regions is needed today, e.g., for the assessment of wind resources. Synthetic Aperture Radar (SAR) is the only satellite borne sensor that has enough resolution to resolve wind speeds closer than 10 km to shore but the Geophysical Model Functions (GMF) used...... for SAR wind retrieval are not fully validated here. Ground based scanning light detection and ranging (LiDAR) offer high horizontal resolution wind velocity measurements with high accuracy, also in the coastal zone. This study, for the first time, examines accuracies of SAR wind retrievals at 10 m height...... with respect to the distance to shore by validation against scanning LiDARs. Comparison of 15 Sentinel-1A wind retrievals using the GMF called C-band model 5.N (CMOD5.N) versus LiDARs show good agreement. It is found, when nondimenionalising with a reference point, that wind speed reductions are between 4...

  7. Observation of the Starting and Low Speed Behavior of Small Horizontal Axis Wind Turbine

    Directory of Open Access Journals (Sweden)

    Sikandar Khan

    2014-01-01

    Full Text Available This paper describes the starting behavior of small horizontal axis wind turbines at high angles of attack and low Reynolds number. The unfavorable relative wind direction during the starting time leads to low starting torque and more idling time. Wind turbine models of sizes less than 5 meters were simulated at wind speed range of 2 m/s to 5 m/s. Wind turbines were modeled in Pro/E and based on the optimized designs given by MATLAB codes. Wind turbine models were simulated in ADAMS for improving the starting behavior. The models with high starting torques and less idling times were selected. The starting behavior was successfully improved and the optimized wind turbine models were able to produce more starting torque even at wind speeds less than 5 m/s.

  8. Impact of Wind Speed Correlation on the Operation of Energy Storage Systems

    Directory of Open Access Journals (Sweden)

    Davril Mathieu

    2016-01-01

    Full Text Available Renewable resources technologies such as wind power currently demonstrate a worldwide popularity thanks to their environmental friendly status and their economic potential. The variability of the wind power output implies the use of practical solutions such as energy storage systems in order to retain the power system stability and reliability. The wind geographical correlation between different wind farms also impacts the system reliability. This paper studies the effects of the wind speed correlation level on the performance of the associated energy storage system (ESS. Wind correlated model using Weibull probability distribution and Nataf transformation is presented. Energy storage system model and energy management algorithm are developed. Both are applied to a modified IEEE-RTS power generation and load model. The case simulation results indicate that the wind speed correlation level between two wind farms impacts the power distribution inside energy storages and that it needs to be considered in order not to overestimate ESS benefits on the system.

  9. LIDAR wind speed measurements from a rotating spinner (SpinnerEx 2009)

    DEFF Research Database (Denmark)

    Angelou, Nikolas; Mikkelsen, Torben; Hansen, Kasper Hjorth

    spinner of a MW-sized wind turbine, and investigate the approaching wind fields from this vantage point. Time series of wind speed measurements from the lidar with 50 Hz sampling rate were successfully obtained for approximately 60 days, during the measurement campaign lasting from April to August 2009...... and the wind turbine’s yaw relative to the mean wind speed direction. The data analysis processes are documented. A methodology for the calculation of the yaw misalignment of the wind turbine relative to the wind direction, as a function of various averaging times, is proposed, using the lidar’s instantaneous...... the lidar measurements. Data from an adjacent meteorological mast as well as data logged within the wind turbine’s control system were used to evaluate the results....

  10. Accounting for the speed shear in wind turbine power performance measurement

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, R.

    2010-04-15

    The power curve of a wind turbine is the primary characteristic of the machine as it is the basis of the warranty for it power production. The current IEC standard for power performance measurement only requires the measurement of the wind speed at hub height and the air density to characterise the wind field in front of the turbine. However, with the growing size of the turbine rotors during the last years, the effect of the variations of the wind speed within the swept rotor area, and therefore of the power output, cannot be ignored any longer. Primary effects on the power performance are from the vertical wind shear and the turbulence intensity. The work presented in this thesis consists of the description and the investigation of a simple method to account for the wind speed shear in the power performance measurement. Ignoring this effect was shown to result in a power curve dependant on the shear condition, therefore on the season and the site. It was then proposed to use an equivalent wind speed accounting for the whole speed profile in front of the turbine. The method was first tested with aerodynamic simulations of a multi-megawatt wind turbine which demonstrated the decrease of the scatter in the power curve. A power curve defined in terms of this equivalent wind speed would be less dependant on the shear than the standard power curve. The equivalent wind speed method was then experimentally validated with lidar measurements. Two equivalent wind speed definitions were considered both resulting in the reduction of the scatter in the power curve. As a lidar wind profiler can measure the wind speed at several heights within the rotor span, the wind speed profile is described with more accuracy than with the power law model. The equivalent wind speed derived from measurements, including at least one measurement above hub height, resulted in a smaller scatter in the power curve than the equivalent wind speed derived from profiles extrapolated from measurements

  11. Control of variable speed wind turbine with doubly-fed induction generator

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, A.D.; Soerensen, P. [Risoe National Lab., Wind Energy Dept., Roskilde (Denmark); Iov, F.; Blaabjerg, F. [Aalborg Univ., Inst. of Energy Technology, Aalborg (Denmark)

    2004-07-01

    draIn this paper, a Control method suitable for a variable speed grid connected pitch-controlled wind turbine with doubly-fed induction generator (DFIG) is developed. The targets of the Control system are: 1) to Control the power drawn from the wind turbine in order to track the wind turbine optimum operation point 2) to limit the power in case of high wind speeds and 3) to Control the reactive power interchanged between the wind turbine generator and the grid. The considered configuration of DFIG is an induction generator with a wound rotor connected to the grid through a back-to-back power converter and a stator directly connected to the grid. The paper presents the overall Control system of the variable speed DFIG wind turbine, with focus on the Control strategies and algorithms applied at each hierarchical Control level of the wind turbine. There are two Control levels: a DFIG Control level and wind turbine Control level. The DFIG Control level contains a fast Control of the power converter and of the doubly-fed induction generator and it has as goal to Control the active and reactive power of the wind turbine independently. The wind turbine Control level supervises with Control signals both the DFIG Control level and the hydraulic pitch Control system of the wind turbine. The present Control method is designed for normal continuous operations. The variable speed/variable pitch wind turbine with doubly-fed induction generator is implemented in the dynamic power system simulation tool DIgSILENT, which makes possible to investigate the dynamic performance of gid-connected wind turbines as a part of realistic electrical grid models. Several significant simulation results are performed With the overall Control-implemented algorithm applied on a variable speed, variable pitch wind turbine model. (au)

  12. Analytical calculation of the minimum wind speed required to sustain wind-blown sand on Earth and Mars

    CERN Document Server

    Kok, Jasper F

    2010-01-01

    The wind-driven hopping motion of sand grains, known as saltation, forms dunes and ripples and ejects fine dust particles into the atmosphere on both Earth and Mars. While the wind speed at which saltation is initiated, the fluid threshold, has been studied extensively, the wind speed at which it is halted, the impact threshold, has been poorly quantified for Mars conditions. We present an analytical model of the impact threshold, which we show to be in agreement with measurements and recent numerical simulations for Earth conditions. For Mars conditions, we find that the impact threshold is approximately an order of magnitude below the fluid threshold, in agreement with previous studies. Saltation on Mars can thus be sustained at wind speeds an order of magnitude less than required to initiate it, leading to the occurrence of hysteresis. These results confirm earlier simulations with a detailed numerical saltation model, and have important implications for the formation of sand dunes, ripples, and dust storm...

  13. First and second order semi-Markov chains for wind speed modeling

    CERN Document Server

    D'Amico, Guglielmo; Prattico, Flavio

    2012-01-01

    The increasing interest in renewable energy, particularly in wind, has given rise to the necessity of accurate models for the generation of good synthetic wind speed data. Markov chains are often used with this purpose but better models are needed to reproduce the statistical properties of wind speed data. We downloaded a database, freely available from the web, in which are included wind speed data taken from L.S.I. -Lastem station (Italy) and sampled every 10 minutes. With the aim of reproducing the statistical properties of this data we propose the use of three semi-Markov models. We generate synthetic time series for wind speed by means of Monte Carlo simulations. The time lagged autocorrelation is then used to compare statistical properties of the proposed models with those of real data and also with a synthetic time series generated though a simple Markov chain.

  14. A global study of temporal and spatial variation of SWH and wind speed and their correlation

    Institute of Scientific and Technical Information of China (English)

    HAN Shuzong; ZHANG Huirong; ZHENG Yunxia

    2014-01-01

    The climatology of significant wave height (SWH) and sea surface wind speed are matters of concern in the fields of both meteorology and oceanography because they are very important parameters for planning offshore structures and ship routings. The TOPEX/Poseidon altimeter, which collected data for about 13 years from September 1992 to October 2005, has measured SWHs and surface wind speeds over most of the world’s oceans. In this paper, a study of the global spatiotemporal distributions and variations of SWH and sea surface wind speed was conducted using the TOPEX/Poseidon altimeter data set. The range and char-acteristics of the variations were analyzed quantitatively for the Pacific, Atlantic, and Indian oceans. Areas of rough waves and strong sea surface winds were localized precisely, and the correlation between SWH and sea surface wind speed analyzed.

  15. On the relationship of radar backscatter to wind speed and fetch. [ocean wave generation

    Science.gov (United States)

    Ross, D.; Jones, W. L.

    1978-01-01

    The physics of the interaction of electromagnetic waves with the ocean surface has been an active area of research for a number of years. This paper contains the results of satellite and aircraft experiments to investigate the ability of active microwave radars to infer surface wind speeds remotely. Data obtained from the recent National Aeronautics and Space Administration (NASA) Skylab experiment are compared with surface wind speeds measured by low-flying aircraft and ships-of-opportunity and found to give useful estimates of the ocean wind field. Also investigated was the influence of varying wave height on radar measurements of wind speed by measuring the backscattering cross-section for constant wind speed but variable wave conditions. It is found that this effect is of little importance.

  16. Cost-Effective Shaft Torque Observer for Condition Monitoring of Wind Turbines

    DEFF Research Database (Denmark)

    Perisic, Nevena; Kirkegaard, Poul Henning; Pedersen, Bo Juul

    2015-01-01

    Improvement of condition monitoring (CM) systems for wind turbines (WTs) and reduction of the cost of wind energy are possible if knowledge about the condition of different WT components is available. CM based on the WT drive train shaft torque signal can give a better understanding of the gearbox...... suggests a novel approach for low-cost, indirect monitoring of the shaft torque from standard WT measurements. The shaft torque is estimated recursively from measurements of generator torque, high speed shaft and low speed shaft angular speeds using the well-known Kalman filter theory. The performance...... of the augmented Kalman filter with fading memory (AKFF) is compared with the augmented Kalman filter (AKF) using simulated data of theWT for different load conditions, measurement noise levels andWT fault scenarios. A multiple-model algorithm, based on a set of different Kalman filters, is designed for practical...

  17. Modeling and Application of PMSG Based Variable Speed Wind Generation System

    Directory of Open Access Journals (Sweden)

    S. Sajedi

    2012-04-01

    Full Text Available In the early development of wind energy, the majority of wind turbines were operated at constant speed. Recently, the number of variable-speed wind turbines installed in wind farms has increased and more wind turbine manufacturers are making variable-speed wind turbines. In this study maximum power control of wind turbine and permanent magnet synchronous generator connected with two back to back voltage source converters to grid are studied. Machine currents are controlled by indirect vector control method. In this method, generator side converter controls the maximum excitation (air gap flux by machine's d-axis current and controls generator torque by machine's q-axis current. PMSG speed is controlled by Tip Speed Ratio (TSR upon the wind speed variations to generate the maximum output power. Grid side converter regulates the DC link voltage and injective active power by d-axis current and regulates the injective reactive power by q-axis current using simple control method P-Q. Simulation results depict that the proposed method operates properly.

  18. High wind speeds prevent formation of a distinct bacterioneuston community in the sea-surface microlayer.

    Science.gov (United States)

    Rahlff, Janina; Stolle, Christian; Giebel, Helge-Ansgar; Brinkhoff, Thorsten; Ribas-Ribas, Mariana; Hodapp, Dorothee; Wurl, Oliver

    2017-05-01

    The sea-surface microlayer (SML) at the boundary between atmosphere and hydrosphere represents a demanding habitat for bacteria. Wind speed is a crucial but poorly studied factor for its physical integrity. Increasing atmospheric burden of CO2, as suggested for future climate scenarios, may particularly act on this habitat at the air-sea interface. We investigated the effect of increasing wind speeds and different pCO2 levels on SML microbial communities in a wind-wave tunnel, which offered the advantage of low spatial and temporal variability. We found that enrichment of bacteria in the SML occurred solely at a U10 wind speed of ≤5.6 m s-1 in the tunnel and ≤4.1 m s-1 in the Baltic Sea. High pCO2 levels further intensified the bacterial enrichment in the SML during low wind speed. In addition, low wind speed and pCO2 induced the formation of a distinctive bacterial community as revealed by 16S rRNA gene fingerprints and influenced the presence or absence of individual taxonomic units within the SML. We conclude that physical stability of the SML below a system-specific wind speed threshold induces specific bacterial communities in the SML entailing strong implications for ecosystem functioning by wind-driven impacts on habitat properties, gas exchange and matter cycling processes. © FEMS 2017.

  19. A Hybrid Wavelet Transform Based Short-Term Wind Speed Forecasting Approach

    Science.gov (United States)

    Wang, Jujie

    2014-01-01

    It is important to improve the accuracy of wind speed forecasting for wind parks management and wind power utilization. In this paper, a novel hybrid approach known as WTT-TNN is proposed for wind speed forecasting. In the first step of the approach, a wavelet transform technique (WTT) is used to decompose wind speed into an approximate scale and several detailed scales. In the second step, a two-hidden-layer neural network (TNN) is used to predict both approximated scale and detailed scales, respectively. In order to find the optimal network architecture, the partial autocorrelation function is adopted to determine the number of neurons in the input layer, and an experimental simulation is made to determine the number of neurons within each hidden layer in the modeling process of TNN. Afterwards, the final prediction value can be obtained by the sum of these prediction results. In this study, a WTT is employed to extract these different patterns of the wind speed and make it easier for forecasting. To evaluate the performance of the proposed approach, it is applied to forecast Hexi Corridor of China's wind speed. Simulation results in four different cases show that the proposed method increases wind speed forecasting accuracy. PMID:25136699

  20. A hybrid wavelet transform based short-term wind speed forecasting approach.

    Science.gov (United States)

    Wang, Jujie

    2014-01-01

    It is important to improve the accuracy of wind speed forecasting for wind parks management and wind power utilization. In this paper, a novel hybrid approach known as WTT-TNN is proposed for wind speed forecasting. In the first step of the approach, a wavelet transform technique (WTT) is used to decompose wind speed into an approximate scale and several detailed scales. In the second step, a two-hidden-layer neural network (TNN) is used to predict both approximated scale and detailed scales, respectively. In order to find the optimal network architecture, the partial autocorrelation function is adopted to determine the number of neurons in the input layer, and an experimental simulation is made to determine the number of neurons within each hidden layer in the modeling process of TNN. Afterwards, the final prediction value can be obtained by the sum of these prediction results. In this study, a WTT is employed to extract these different patterns of the wind speed and make it easier for forecasting. To evaluate the performance of the proposed approach, it is applied to forecast Hexi Corridor of China's wind speed. Simulation results in four different cases show that the proposed method increases wind speed forecasting accuracy.

  1. A Hybrid Wavelet Transform Based Short-Term Wind Speed Forecasting Approach

    Directory of Open Access Journals (Sweden)

    Jujie Wang

    2014-01-01

    Full Text Available It is important to improve the accuracy of wind speed forecasting for wind parks management and wind power utilization. In this paper, a novel hybrid approach known as WTT-TNN is proposed for wind speed forecasting. In the first step of the approach, a wavelet transform technique (WTT is used to decompose wind speed into an approximate scale and several detailed scales. In the second step, a two-hidden-layer neural network (TNN is used to predict both approximated scale and detailed scales, respectively. In order to find the optimal network architecture, the partial autocorrelation function is adopted to determine the number of neurons in the input layer, and an experimental simulation is made to determine the number of neurons within each hidden layer in the modeling process of TNN. Afterwards, the final prediction value can be obtained by the sum of these prediction results. In this study, a WTT is employed to extract these different patterns of the wind speed and make it easier for forecasting. To evaluate the performance of the proposed approach, it is applied to forecast Hexi Corridor of China’s wind speed. Simulation results in four different cases show that the proposed method increases wind speed forecasting accuracy.

  2. Stability Augmentation of Wind Farm using Variable Speed Permanent Magnet Synchronous Generator

    Science.gov (United States)

    Rosyadi, Marwan; Muyeen, S. M.; Takahashi, Rion; Tamura, Junji

    This paper presents a new control strategy of variable speed permanent magnet wind generator for stability augmentation of wind farm including fixed speed wind turbine with Induction Generator (IG). A new control scheme is developed for two levels back-to-back converters of Permanent Magnet Synchronous Generator (PMSG), by which both active and reactive powers delivered to the grid can be controlled easily. To avoid the converter damage, the DC link protection controller is also proposed in order to protect the dc link circuit during fault condition. To evaluate the control capability of the proposed controllers, simulations are performed on two model systems composed of wind farms connected to an infinite bus. From transient and steady state analyses by using PSCAD/EMTDC, it is concluded that the proposed control scheme is very effective to improve the stability of wind farm for severe network disturbance and randomly fluctuating wind speed.

  3. Variations in long term wind speed during different decades in Arabian Sea and Bay of Bengal

    Indian Academy of Sciences (India)

    V Sanil Kumar; C Sajiv Philip

    2010-10-01

    A study has been carried out by comparing the extreme wind speeds estimated based on NCEP/NCAR reanalysis data for 100 years return period using Fischer Tippet-1 (commonly known as Gumbel)and Weibull distributions for three locations (off Goa,Visakhapatnam and Machilipatnam)in the north Indian Ocean.The wind dataset for Goa is compared with that from ERA-40 data.For higher wind speeds (12-20 m s−1),NCEP wind speed has higher percentage of occurrence than that of ERA-40.Analysis has shown slight upward trend in the annual maximum wind for location off Machilipatnam with an increase of 1.2cms−1 per year and a decreasing trend of −1.3cms−1 per year in the case of Goa.The Weibull distribution with shape parameter 2 fits the annual maximum wind data better than FT-1 distribution.

  4. Time series analysis of wind speed using VAR and the generalized impulse response technique

    Energy Technology Data Exchange (ETDEWEB)

    Ewing, Bradley T. [Area of Information Systems and Quantitative Sciences, Rawls College of Business and Wind Science and Engineering Research Center, Texas Tech University, Lubbock, TX 79409-2101 (United States); Kruse, Jamie Brown [Center for Natural Hazard Research, East Carolina University, Greenville, NC (United States); Schroeder, John L. [Department of Geosciences and Wind Science and Engineering Research Center, Texas Tech University, Lubbock, TX (United States); Smith, Douglas A. [Department of Civil Engineering and Wind Science and Engineering Research Center, Texas Tech University, Lubbock, TX (United States)

    2007-03-15

    This research examines the interdependence in time series wind speed data measured in the same location at four different heights. A multiple-equation system known as a vector autoregression is proposed for characterizing the time series dynamics of wind. Additionally, the recently developed method of generalized impulse response analysis provides insight into the cross-effects of the wind series and their responses to shocks. Findings are based on analysis of contemporaneous wind speed time histories taken at 13, 33, 70 and 160 ft above ground level with a sampling rate of 10 Hz. The results indicate that wind speeds measured at 70 ft was the most variable. Further, the turbulence persisted longer at the 70-ft measurement than at the other heights. The greatest interdependence is observed at 13 ft. Gusts at 160 ft led to the greatest persistence to an 'own' shock and led to greatest persistence in the responses of the other wind series. (author)

  5. Neuron-Adaptive PID Based Speed Control of SCSG Wind Turbine System

    Directory of Open Access Journals (Sweden)

    Shan Zuo

    2014-01-01

    Full Text Available In searching for methods to increase the power capacity of wind power generation system, superconducting synchronous generator (SCSG has appeared to be an attractive candidate to develop large-scale wind turbine due to its high energy density and unprecedented advantages in weight and size. In this paper, a high-temperature superconducting technology based large-scale wind turbine is considered and its physical structure and characteristics are analyzed. A simple yet effective single neuron-adaptive PID control scheme with Delta learning mechanism is proposed for the speed control of SCSG based wind power system, in which the RBF neural network (NN is employed to estimate the uncertain but continuous functions. Compared with the conventional PID control method, the simulation results of the proposed approach show a better performance in tracking the wind speed and maintaining a stable tip-speed ratio, therefore, achieving the maximum wind energy utilization.

  6. Wind speed affects prey-catching behaviour in an orb web spider

    Science.gov (United States)

    Turner, Joe; Vollrath, Fritz; Hesselberg, Thomas

    2011-12-01

    Wind has previously been shown to influence the location and orientation of spider web sites and also the geometry and material composition of constructed orb webs. We now show that wind also influences components of prey-catching behaviour within the web. A small wind tunnel was used to generate different wind speeds. Araneus diadematus ran more slowly towards entangled Drosophila melanogaster in windy conditions, which took less time to escape the web. This indicates a lower capture probability and a diminished overall predation efficiency for spiders at higher wind speeds. We conclude that spiders' behaviour of taking down their webs as wind speed increases may therefore not be a response only to possible web damage.

  7. Variable speed wind turbine generator system with current controlled voltage source inverter

    Energy Technology Data Exchange (ETDEWEB)

    Muyeen, S.M., E-mail: muyeen0809@yahoo.co [Dept. of Electrical Engineering, Petroleum Institute, P.O. Box 2533, Abu Dhabi (United Arab Emirates); Al-Durra, Ahmed [Dept. of Electrical Engineering, The Petroleum Institute, P.O. Box 2533, Abu Dhabi (United Arab Emirates); Tamura, J. [Dept. of EEE, Kitami Institute of Technology, 165 Koen-cho, Kitami 090-8507 (Japan)

    2011-07-15

    highlights: {yields} Current controlled voltage source inverter scheme for wind power application. {yields} Low voltage ride through of wind farm. {yields} Variable speed wind turbine driven permanent magnet synchronous generator-operation and control. -- Abstract: The present popular trend of wind power generation is to use variable speed wind turbine (VSWT) driving a doubly fed induction generator (DFIG), wound field synchronous generator (WFSG) or permanent magnet synchronous generator (PMSG). Among them, stability analyses of DFIG type of VSWT have already been reported in many literatures. However, transient stability and low voltage ride through (LVRT) characteristics analyses for synchronous generator type of VSWT is not sufficient enough. This paper focuses on detailed LVRT characteristic analysis of variable speed wind turbine driving a PMSG (VSWT-PMSG) with current controlled voltage source inverter (CC-VSI). Modeling and suitable control strategies for overall system are developed to augment the low voltage ride through capability of variable speed wind generator, considering recent wind farm grid code. Both symmetrical and unsymmetrical faults are analyzed as network disturbances in this paper. The permanent fault due to unsuccessful reclosing of circuit breakers is taken into consideration, which is a salient feature of this study. Moreover, the dynamic characteristic is analyzed using real wind speed data measured in Hokkaido Island, Japan. The proposed control scheme is simulated by using the standard power system simulation package PSCAD/EMTDC and results are verified by comparing that of voltage controlled voltage source inverter scheme available in power system literature.

  8. Dependency of U.S. Hurricane Economic Loss on Maximum Wind Speed and Storm Size

    CERN Document Server

    Zhai, Alice R

    2014-01-01

    Many empirical hurricane economic loss models consider only wind speed and neglect storm size. These models may be inadequate in accurately predicting the losses of super-sized storms, such as Hurricane Sandy in 2012. In this study, we examined the dependencies of normalized U.S. hurricane loss on both wind speed and storm size for 73 tropical cyclones that made landfall in the U.S. from 1988 to 2012. A multi-variate least squares regression is used to construct a hurricane loss model using both wind speed and size as predictors. Using maximum wind speed and size together captures more variance of losses than using wind speed or size alone. It is found that normalized hurricane loss (L) approximately follows a power law relation with maximum wind speed (Vmax) and size (R). Assuming L=10^c Vmax^a R^b, c being a scaling factor, the coefficients, a and b, generally range between 4-12 and 2-4, respectively. Both a and b tend to increase with stronger wind speed. For large losses, a weighted regression model, with...

  9. Ammonia removal from water: The comparison between using the wind speed and agitation method

    Directory of Open Access Journals (Sweden)

    Intamanee, J.

    2005-01-01

    Full Text Available Ammonia removal from skim latex is an essential step in skim block production process. In general, skim latex contains about 0.4% ammonia by weight of skim latex and needs to be reduced in order to minimize acid usage during rubber coagulation step. The method used to remove ammonia from skim latex in many concentrated rubber latex plants is ammonia volatilization by agitating skim latex using a large agitator in a mixing pool. In this research, a new method to remove ammonia from water by blowing wind over the water surface was investigated. The effects of agitation speed and wind speed on overall mass transfer coefficient and removal rate of ammonia were investigated in a pilot scale experiment. The result has shown that the overall mass transfer coefficient and the ammonia removal rate increase linearly with increasing Reynolds number of air and liquid. However, the ammonia removal rate by using wind speed was much higher than that given by agitation method. The wind speed method proposed in this study is then recommended for ammonia removal from skim latex. Possible ways for applying the wind speed method for skim latex production plant are also suggested. The relationship between the wind speed or Reynolds number and the mass transfer coefficient can also be used to design the system for ammonia removal from water byusing wind speed.

  10. Comparing measurements of the horizontal wind speed of a 2D Multi-Lidar and a cup anemometer

    Science.gov (United States)

    Schneemann, Jörge; Trabucchi, Davide; José Trujillo, Juan; Kühn, Martin

    2014-12-01

    Wind measurements of a 2D Multi-Lidar and a mast mounted cup anemometer are compared in this study. Average wind speed and direction as well as the turbulence intensity of the wind speed are considered. Data analysis is mainly performed using standard regression analysis on 10 minute average data and the calculation of the power spectral density. The results show a good agreement regarding wind speed and direction and the turbulence intensity of the horizontal wind.

  11. Control design for a pitch-regulated, variable speed wind turbine

    DEFF Research Database (Denmark)

    Hansen, M.H.; Hansen, Anca Daniela; Larsen, Torben J.;

    2005-01-01

    of tuning the parameters of the frequency converter to obtain a more constant power output. The dynamicmodelling of the power controller is an important result for the inclusion of generator dynamics in the aeroelastic modelling of wind turbines. A reduced dynamic model of the relation between generator...... different, which makes a directly quantitative comparison difficult. But there are some observations of similar behaviours should be mentioned: • Very similar step responses in rotor speed, pitch angle, and powerare seen for simulations with steps in wind speed. • All controllers show a peak in power...... for wind speed step-up over rated wind speed, which can be almost removed by changing the parameters of the frequency converter. • Responses of rotor speed, pitchangle, and power for different simulations with turbulent inflow are similar for all three controllers. Again, there seems to be an advantage...

  12. EU-NORSEWIND - Delivering Offshore Wind Speed Data

    DEFF Research Database (Denmark)

    Oldroyd, Andy; Hasager, Charlotte Bay; Stickland, M.T.

    Offshore wind is the major growth area in the wind industry sector today, with a host of large projects being announced and innovative approaches being proposed. However, with all this investment and innovation there remains a key, fundamental missing element - a thorough understanding...... of the offshore wind climatology and likely wind resource. As the wind industry starts to look in detail at the wind regime offshore, the need for more physical data becomes apparent. As well as the normal AEP requirements for project finance, baseline data is required in order to better understand the local...... conditions with respect to shear and hence loading implications, and of equal concern directionality which can feed into important research areas such as offshore wake propagation. Indeed, a good baseline understanding of the wind flow regime is essential in being able to determine the accumulative impact...

  13. Using Data-Mining Approaches for Wind Turbine Power Curve Monitoring: A Comparative Study

    DEFF Research Database (Denmark)

    Schlechtingen, Meik; Santos, Ilmar; Achiche, Sofiane

    2013-01-01

    Four data-mining approaches for wind turbine power curve monitoring are compared. Power curve monitoring can be applied to evaluate the turbine power output and detect deviations, causing financial loss. In this research, cluster center fuzzy logic, neural network, and -nearest neighbor models...... are built and their performance compared against literature. Recently developed adaptive neuro-fuzzy-interference system models are set up and their performance compared with the other models, using the same data. Literature models often neglect the influence of the ambient temperature and the wind...... direction. The ambient temperature can influence the power output up to 20%. Nearby obstacles can lower the power output for certain wind directions. The approaches proposed in literature and the ANFIS models are compared by using wind speed only and two additional inputs. The comparison is based...

  14. Power Smoothing of a Variable-Speed Wind Turbine Generator in Association With the Rotor-Speed-Dependent Gain

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yeonhee; Kang, Moses; Muljadi, Eduard; Park, Jung-Wook; Kang, Yong Cheol

    2017-07-01

    This paper proposes a power-smoothing scheme for a variable-speed wind turbine generator (WTG) that can smooth out the WTG's fluctuating power caused by varying wind speeds, and thereby keep the system frequency within a narrow range. The proposed scheme employs an additional loop based on the system frequency deviation that operates in conjunction with the maximum power point tracking (MPPT) control loop. Unlike the conventional, fixed-gain scheme, its control gain is modified with the rotor speed. In the proposed scheme, the control gain is determined by considering the ratio of the output of the additional loop to that of the MPPT loop. To improve the contribution of the scheme toward maintaining the frequency while ensuring the stable operation of WTGs, in the low rotor speed region, the ratio is set to be proportional to the rotor speed; in the high rotor speed region, the ratio remains constant. The performance of the proposed scheme is investigated under varying wind conditions for the IEEE 14-bus system. The simulation results demonstrate that the scheme successfully operates regardless of the output power fluctuation of a WTG by adjusting the gain with the rotor speed, and thereby improves the frequency-regulating capability of a WTG.

  15. Flux-tube geometry and solar wind speed during an activity cycle

    Science.gov (United States)

    Pinto, R. F.; Brun, A. S.; Rouillard, A. P.

    2016-07-01

    Context. The solar wind speed at 1 AU shows cyclic variations in latitude and in time which reflect the evolution of the global background magnetic field during the activity cycle. It is commonly accepted that the terminal (asymptotic) wind speed in a given magnetic flux-tube is generally anti-correlated with its total expansion ratio, which motivated the definition of widely used semi-empirical scaling laws relating one to the other. In practice, such scaling laws require ad hoc corrections (especially for the slow wind in the vicinities of streamer/coronal hole boundaries) and empirical fits to in situ spacecraft data. A predictive law based solely on physical principles is still missing. Aims: We test whether the flux-tube expansion is the controlling factor of the wind speed at all phases of the cycle and at all latitudes (close to and far from streamer boundaries) using a very large sample of wind-carrying open magnetic flux-tubes. We furthermore search for additional physical parameters based on the geometry of the coronal magnetic field which have an influence on the terminal wind flow speed. Methods: We use numerical magneto-hydrodynamical simulations of the corona and wind coupled to a dynamo model to determine the properties of the coronal magnetic field and of the wind velocity (as a function of time and latitude) during a whole 11-yr activity cycle. These simulations provide a large statistical ensemble of open flux-tubes which we analyse conjointly in order to identify relations of dependence between the wind speed and geometrical parameters of the flux-tubes which are valid globally (for all latitudes and moments of the cycle). Results: Our study confirms that the terminal (asymptotic) speed of the solar wind depends very strongly on the geometry of the open magnetic flux-tubes through which it flows. The total flux-tube expansion is more clearly anti-correlated with the wind speed for fast rather than for slow wind flows, and effectively controls the

  16. Different Condition Monitoring Approaches for Main Shafts of Offshore Wind Turbines

    DEFF Research Database (Denmark)

    Ambühl, Simon; Sørensen, John Dalsgaard

    Condition monitoring can be used to detect faults and failures at an early stage. Thus it decreases the overall maintenance expenses. This report gives an example of condition monitoring with focus on early crack detection in the main shaft of an offshore wind turbine. This article discusses...... the applicability of different condition monitoring techniques like performance monitoring, strain gauge results and vibration analysis for crack detection on the low speed shaft. Different signal processing methods like descriptive statistics, Fourier Transforms, Wavelet transforms, Modal Assurance Criteria...

  17. A hybrid approach for short-term forecasting of wind speed.

    Science.gov (United States)

    Tatinati, Sivanagaraja; Veluvolu, Kalyana C

    2013-01-01

    We propose a hybrid method for forecasting the wind speed. The wind speed data is first decomposed into intrinsic mode functions (IMFs) with empirical mode decomposition. Based on the partial autocorrelation factor of the individual IMFs, adaptive methods are then employed for the prediction of IMFs. Least squares-support vector machines are employed for IMFs with weak correlation factor, and autoregressive model with Kalman filter is employed for IMFs with high correlation factor. Multistep prediction with the proposed hybrid method resulted in improved forecasting. Results with wind speed data show that the proposed method provides better forecasting compared to the existing methods.

  18. A Hybrid Approach for Short-Term Forecasting of Wind Speed

    Directory of Open Access Journals (Sweden)

    Sivanagaraja Tatinati

    2013-01-01

    Full Text Available We propose a hybrid method for forecasting the wind speed. The wind speed data is first decomposed into intrinsic mode functions (IMFs with empirical mode decomposition. Based on the partial autocorrelation factor of the individual IMFs, adaptive methods are then employed for the prediction of IMFs. Least squares-support vector machines are employed for IMFs with weak correlation factor, and autoregressive model with Kalman filter is employed for IMFs with high correlation factor. Multistep prediction with the proposed hybrid method resulted in improved forecasting. Results with wind speed data show that the proposed method provides better forecasting compared to the existing methods.

  19. Wind Turbine Generator Modeling and Simulation Where Rotational Speed is the Controlled Variable

    DEFF Research Database (Denmark)

    Mihet-Popa, Lucian; Blaabjerg, Frede; Boldea, Ion

    2004-01-01

    the interaction between a wind turbine and the power system. The model is intended to simulate the behaviour of the wind turbine using induction generators both during normal operation. Sample simulation results for two induction generators (2/0.5 MW) validate the fundamental issues....... for application in variable speed wind turbines. The usual strategy is to control the power or the torque acting on the wind turbine shafts. This paper presents an alternative control strategy, where the rotational speed is the controlled variable. The paper describes a model, which is being developed to simulate...

  20. A New Hybrid Forecasting Strategy Applied to Mean Hourly Wind Speed Time Series

    Directory of Open Access Journals (Sweden)

    Stylianos Sp. Pappas

    2014-01-01

    Full Text Available An alternative electric power source, such as wind power, has to be both reliable and autonomous. An accurate wind speed forecasting method plays the key role in achieving the aforementioned properties and also is a valuable tool in overcoming a variety of economic and technical problems connected to wind power production. The method proposed is based on the reformulation of the problem in the standard state space form and on implementing a bank of Kalman filters (KF, each fitting an ARMA model of different order. The proposed method is to be applied to a greenhouse unit which incorporates an automatized use of renewable energy sources including wind speed power.

  1. Flicker Mitigation by Individual Pitch Control of Variable Speed Wind Turbines With DFIG

    DEFF Research Database (Denmark)

    Zhang, Yunqian; Chen, Zhe; Hu, Weihao;

    2014-01-01

    generatorto investigate the flicker emission and mitigation issues. An individual pitch control (IPC) strategy is proposed to reduce the flicker emission at different wind speed conditions. The IPC scheme is proposed and the individual pitch controller is designed according to the generator active power...... and the azimuth angle of the wind turbine. The simulations are performed on the NREL (National Renewable Energy Laboratory) 1.5-MW upwind reference wind turbine model. Simulation results show that damping the generator active power by IPC is an effective means for flicker mitigation of variable speed wind...

  2. A disturbance decoupling nonlinear control law for variable speed wind turbines

    DEFF Research Database (Denmark)

    Thomsen, Sven Creutz; Poulsen, Niels Kjølstad

    2007-01-01

    This paper describes a nonlinear control law for controlling variable speed wind turbines using feedback linearization. The novel aspect of the control law is its ability to decouple the effect of wind fluctuations. Furthermore, the transformation to feedback linearizable coordinates is chosen...... intelligently so that the majority of the system structure is invariant under the transformation. Consequently the physical interpretation is preserved. The method assumes that the effective wind speed and acceleration are estimated from measurements on the wind turbine. The performance of the control...

  3. Winds measured by the Rover Environmental Monitoring Station (REMS) during Curiosity's Bagnold Dunes Campaign

    Science.gov (United States)

    Newman, Claire E.; Gomez-Elvira, Javier; Navarro Lopez, Sara; Marin Jimenez, Mercedes; Torres Redondo, Josefina; Richardson, Mark I.

    2016-10-01

    Curiosity's damaged wind sensor has trouble measuring winds coming from behind the rover, due to the loss of its side-pointing boom during landing. During the Bagnold Dunes Campaign, however, the rover was turned to permit measurements of winds from missing directions, capturing upslope/downslope day-night flow on the slopes of Aeolis Mons and blocking of wind in the lee of a dune.The rover's heading is generally determined by the drive direction and often varies little over many tens of sols. Good wind measurements are made when the wind comes from the hemisphere to the front of the rover, but there are sometimes long periods during which winds from certain directions (i.e., at certain times of sol) are largely missed. Since rover turns are often precluded by rover safety and other operational constraints, it is usually not possible to turn to measure such winds properly.During the Bagnold Dunes Campaign, wind measurements were prioritized to provide context for aeolian dune studies. Rover headings were optimized for three wind investigations covering a period of about 90 sols. The first investigation characterized the wind field on approach to the dunes, with the rover turned to face two unusual headings for several sols each and monitoring focused on the 'missing' winds / times of sol. This confirmed the expected primary wind pattern of daytime roughly upslope winds (from ~NW/N) and nighttime downslope winds (from ~S/SE) on the slopes of Aeolis Mons, with significant sol-to-sol variability in e.g. the timing of the reversals. Comparison with the previous year suggests an increasingly upslope-downslope pattern as Curiosity approached the slope.The second investigation studied changes to the wind pattern in the lee of the Namib Dune. This revealed the blocking of northerly winds by the large dune, leaving primarily a westerly component to the daytime winds with weaker wind speeds.The third investigation characterized the wind field at the side of Namib Dune. The

  4. Time Series Analysis and Forecasting for Wind Speeds Using Support Vector Regression Coupled with Artificial Intelligent Algorithms

    OpenAIRE

    Ping Jiang; Shanshan Qin; Jie Wu; Beibei Sun

    2015-01-01

    Wind speed/power has received increasing attention around the earth due to its renewable nature as well as environmental friendliness. With the global installed wind power capacity rapidly increasing, wind industry is growing into a large-scale business. Reliable short-term wind speed forecasts play a practical and crucial role in wind energy conversion systems, such as the dynamic control of wind turbines and power system scheduling. In this paper, an intelligent hybrid model for short-term ...

  5. Environmental Monitoring - Lillgrund Offshore Wind Farm. Lillgrund Pilot Project

    Energy Technology Data Exchange (ETDEWEB)

    Davy, Thomas (Vattenfall Vindkraft AB, Stockholm (Sweden))

    2009-02-15

    225 m3 which is significantly lower than the max stipulated 200 000 m3, due to the fact that vessels able to operate in shallow waters were used. The method used for the dredging was also adjusted to reduce the amount of spillage. The total dredged volume was 68 598 m3 for cable work, which is well below the stipulated max of 100 000 m3. For the feedback control on flora and fauna, the key environmental parameters were eel grass and common sea mussels. No negative impacts were observed during construction. For possible effects on the nearby coastline, a monitoring program has been performed, including a baseline study and follow-up studies. The follow-up study was performed during autumn 2008 and results show no negative effects on the nearby coastline from the construction of the wind farm. To ensure that the contractors worked in accordance with the Swedish requirements for 'operators control', audits of their management systems were performed checking their procedures for fulfilling legal requirements and other environmental requirements. Audits were also performed on site, based on the above-mentioned checklist. The procedure worked well and no major deviations were found at the audits performed. For all minor deviations corrective actions were taken accordingly. A number of further environmental monitoring programs are performed including studies on: - Birds; - Fish and Fishing; - Infauna above cables (part of the Flora and Fauna program); - Noise. Baseline studies on noise have been performed and show that the equivalent noise level measured varied between 31-46 dB(A) at wind speeds between 2-8 m/s. This means that the background noise level for longer periods is above the max noise level stated by the authorities. However, the consultants conclusion from the baseline studies is that it will be possible to perform immission measurements as planned, given the correct weather conditions and times are chosen. Baseline studies on fish, fishing and birds

  6. Development of Wind Power Generation Model with DFIG for Varying Wind Speed and Frequency Control for Wind Diesel Power Plant

    Directory of Open Access Journals (Sweden)

    Naresh Kumari

    2016-04-01

    Full Text Available The power generation with non-renewable energy sources has very harmful effects on the environment as well as these sources are depleting. On the other side the renewable energy sources are quite unpredictable source of power. The best trade-off is to use the combination of both kind of sources to make a hybrid system so that their individual power generation constraints can be overcome. The hybrid system taken for analysis in this work comprises of wind and diesel power generation systems. The complete modelling of the system has been done in MATLAB/SIMULINK environment. Doubly fed induction generator (DFIG is used for power generation in wind power system. The modelling has been done considering the changing wind speed and varying load conditions. The mathematical models of DFIG and diesel power generator have been used to develop the simulink model which can be used for analysis of various performances of the system like frequency response and power sharing between different sources with load variation .The generating margin of DFIG is also simulated for the frequency support during varying load conditions .The generating margin is created by the control of active power output from DFIG. Also as the power demand rises the generating margin of DFIG keeps the balance between the power generation and load. Proportional Integral controller has been used for diesel generator plant for frequency control. The controller gains have been optimized with Particle Swarm Optimization technique. The proper selection of controller gains and wind power reserve help to achieve the enhanced frequency response of the hybrid system.

  7. De-trending of wind speed variance based on first-order and second-order statistical moments only

    DEFF Research Database (Denmark)

    Larsen, Gunner Chr.; Hansen, Kurt Schaldemose

    2014-01-01

    statistical data only. The first model is a pure time series analysis approach, which quantifies the effect of non-stationary characteristics of ensemble mean wind speeds on the estimated wind speed standard deviations as based on mean wind speed statistics only. This model is applicable to statistics......The lack of efficient methods for de-trending of wind speed resource data may lead to erroneous wind turbine fatigue and ultimate load predictions. The present paper presents two models, which quantify the effect of an assumed linear trend on wind speed standard deviations as based on available...... of arbitrary types of time series. The second model uses the full set of information and includes thus additionally observed wind speed standard deviations to estimate the effect of ensemble mean non-stationarities on wind speed standard deviations. This model takes advantage of a simple physical relationship...

  8. Rainband, Feature Tracking for Wind Speeds Around Typhoon Eyes Using Multiple Sensors

    Science.gov (United States)

    He, S.; Liu, A. K.; Yu, C.-K.

    2016-08-01

    In this study, five typhoon cases observed by quasi-concurrent satellite-based Synthetic Aperture Radar (SAR) and Moderate Resolution Imaging Spectroradiometer (MODIS) data, and one of the cases also by ground-based Doppler radar observations have been studied. The rainband features around typhoon eyes are first delineated using wavelet analysis, and then the wind speeds are estimated by feature tracking using quasi-concurrent multi-sensor images.It was found that the resulting wind speeds are reasonable compared with the maximum wind speed reported by the Joint Typhoon Warning Center (JTWC), which accounts for the radial dependence of wind speed using the Rankine combined vortex approximation. In a specific case, with the aid of Doppler radar near the coast, wind speed estimation based on the multi-sensor also shows consistent results. This study demonstrates that the local wind distribution of cyclonic winds around typhoon eyes at different radial distances from the typhoon centers may be derived from rainband feature tracking using quasi-concurrent multi-sensor images. This technique may offer useful wind information for typhoon simulations and forecasting.

  9. Identification and Attribution of Global Wind Speed Trends at 100m

    Science.gov (United States)

    McGraw, Zachary; Smith, Ronald; Storelvmo, Trude

    2016-04-01

    Recent studies have found evidence that global climate change significantly alters the strength of large-scale wind patterns. Any enduring trends over large regions are potentially of value to understand due to their implications for the wind energy industry. In this study we identify and evaluate global wind speed trends at the wind turbine hub height (~100m) through the use of CMIP5 models, standard reanalyses (ERA-Interim, NCEP2) and a uniquely high-resolution analysis dataset (Vestas Mesoscale Library). By analyzing how wind speeds change across the globe throughout the period 1900-2100 (with emphasis on the satellite era, 1979-2014), we assess the significance of multi-decadal wind speed trends in the context of natural spatial and temporal variability. Our results show substantial differences in regional trends between different datasets though several regions including the Southern Hemisphere mid-latitudes and the Caribbean show consistently substantial changing wind speeds during the satellite era. Wind speed trends tend to diminish over large time scales and follow spatial patterns that link multi-decadal trends to the evolving behaviors of internal variability modes, especially those of ENSO and the Southern Annular Mode (SAM).

  10. Wind speed estimation using C-band compact polarimetric SAR for wide swath imaging modes

    Science.gov (United States)

    Denbina, Michael; Collins, Michael J.

    2016-03-01

    We have investigated the use of C-band compact polarimetric synthetic aperture radar for estimation of ocean surface wind speeds. Using 1399 buoy observations collocated with Radarsat-2 scenes, compact polarimetric data was simulated for two of the Radarsat Constellation's planned wide swath imaging modes. Provided the wind direction is known or can be estimated, our results demonstrate that wind speed can be estimated from the right-vertical polarization channel of the compact polarimetry using a combination of the CMOD5 geophysical model function and a linear model. If wind speed estimation without wind direction input is desired, the randomly-polarized component of the backscattered power can be used in a similar fashion to that of the linear cross-polarizations, but is less affected by increases in the noise effective sigma-zero of the data. A model is proposed for the randomly-polarized power as a function of incidence angle and wind speed, independent of wind direction. The results suggest that compact polarimetry is a strong alternative to linearly polarized synthetic aperture radar data for wind speed estimation applications, particularly for wide swath imaging modes with a high noise floor.

  11. Load Mitigation and Optimal Power Capture for Variable Speed Wind Turbine in Region 2

    Directory of Open Access Journals (Sweden)

    Saravanakumar Rajendran

    2015-01-01

    Full Text Available This paper proposes the two nonlinear controllers for variable speed wind turbine (VSWT operating at below rated wind speed. The objective of the controller is to maximize the energy capture from the wind with reduced oscillation on the drive train. The conventional controllers such as aerodynamic torque feedforward (ATF and indirect speed control (ISC are adapted initially, which introduce more power loss, and the dynamic aspects of WT are not considered. In order to overcome the above drawbacks, modified nonlinear static state with feedback estimator (MNSSFE and terminal sliding mode controller (TSMC based on Modified Newton Raphson (MNR wind speed estimator are proposed. The proposed controllers are simulated with nonlinear FAST (fatigue, aerodynamics, structures, and turbulence WT dynamic simulation for different mean wind speeds at below rated wind speed. The frequency analysis of the drive train torque is done by taking the power spectral density (PSD of low speed shaft torque. From the result, it is found that a trade-off is to be maintained between the transient load on the drive train and maximum power capture.

  12. Environmental Monitoring - Lillgrund Offshore Wind Farm. Lillgrund Pilot Project

    Energy Technology Data Exchange (ETDEWEB)

    Davy, Thomas (Vattenfall Vindkraft AB, Stockholm (Sweden))

    2009-02-15

    225 m3 which is significantly lower than the max stipulated 200 000 m3, due to the fact that vessels able to operate in shallow waters were used. The method used for the dredging was also adjusted to reduce the amount of spillage. The total dredged volume was 68 598 m3 for cable work, which is well below the stipulated max of 100 000 m3. For the feedback control on flora and fauna, the key environmental parameters were eel grass and common sea mussels. No negative impacts were observed during construction. For possible effects on the nearby coastline, a monitoring program has been performed, including a baseline study and follow-up studies. The follow-up study was performed during autumn 2008 and results show no negative effects on the nearby coastline from the construction of the wind farm. To ensure that the contractors worked in accordance with the Swedish requirements for 'operators control', audits of their management systems were performed checking their procedures for fulfilling legal requirements and other environmental requirements. Audits were also performed on site, based on the above-mentioned checklist. The procedure worked well and no major deviations were found at the audits performed. For all minor deviations corrective actions were taken accordingly. A number of further environmental monitoring programs are performed including studies on: - Birds; - Fish and Fishing; - Infauna above cables (part of the Flora and Fauna program); - Noise. Baseline studies on noise have been performed and show that the equivalent noise level measured varied between 31-46 dB(A) at wind speeds between 2-8 m/s. This means that the background noise level for longer periods is above the max noise level stated by the authorities. However, the consultants conclusion from the baseline studies is that it will be possible to perform immission measurements as planned, given the correct weather conditions and times are chosen. Baseline studies on fish, fishing and birds

  13. Wind speed reductions by large-scale wind turbine deployments lower turbine efficiencies and set low generation limits.

    Science.gov (United States)

    Miller, Lee M; Kleidon, Axel

    2016-11-29

    Wind turbines generate electricity by removing kinetic energy from the atmosphere. Large numbers of wind turbines are likely to reduce wind speeds, which lowers estimates of electricity generation from what would be presumed from unaffected conditions. Here, we test how well wind power limits that account for this effect can be estimated without explicitly simulating atmospheric dynamics. We first use simulations with an atmospheric general circulation model (GCM) that explicitly simulates the effects of wind turbines to derive wind power limits (GCM estimate), and compare them to a simple approach derived from the climatological conditions without turbines [vertical kinetic energy (VKE) estimate]. On land, we find strong agreement between the VKE and GCM estimates with respect to electricity generation rates (0.32 and 0.37 We m(-2)) and wind speed reductions by 42 and 44%. Over ocean, the GCM estimate is about twice the VKE estimate (0.59 and 0.29 We m(-2)) and yet with comparable wind speed reductions (50 and 42%). We then show that this bias can be corrected by modifying the downward momentum flux to the surface. Thus, large-scale limits to wind power use can be derived from climatological conditions without explicitly simulating atmospheric dynamics. Consistent with the GCM simulations, the approach estimates that only comparatively few land areas are suitable to generate more than 1 We m(-2) of electricity and that larger deployment scales are likely to reduce the expected electricity generation rate of each turbine. We conclude that these atmospheric effects are relevant for planning the future expansion of wind power.

  14. 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.

  15. Designing, Constructing, And Testing A Low – Speed Open – Jet Wind Tunnel

    Directory of Open Access Journals (Sweden)

    Nguyen Quoc Y

    2014-01-01

    Full Text Available A low-speed wind tunnel has been built and tested in the Laboratory of Fluid Mechanics at the Hochiminh City University of Technology for teaching and doing research. The wind tunnel is an open-jet type with the nozzle area of 1m x 1m and the maximum wind speed of 14 m/s. To evaluate quality of the wind flow created by the tunnel, velocity distribution and turbulence intensity of airflow were measured at the nozzle by a thermal-couple anemometer. The measurements indicated that the turbulence intensity was less than two percent while the uniformity of wind speed across the nozzle is more than ninety five percent.

  16. Wind speed forecasting at different time scales: a non parametric approach

    CERN Document Server

    D'Amico, Guglielmo; Prattico, Flavio

    2013-01-01

    The prediction of wind speed is one of the most important aspects when dealing with renewable energy. In this paper we show a new nonparametric model, based on semi-Markov chains, to predict wind speed. Particularly we use an indexed semi-Markov model, that reproduces accurately the statistical behavior of wind speed, to forecast wind speed one step ahead for different time scales and for very long time horizon maintaining the goodness of prediction. In order to check the main features of the model we show, as indicator of goodness, the root mean square error between real data and predicted ones and we compare our forecasting results with those of a persistence model.

  17. Ensemble standar deviation of wind speed and direction of the FDDA input to WRF

    Data.gov (United States)

    U.S. Environmental Protection Agency — NetCDF file of the SREF standard deviation of wind speed and direction that was used to inject variability in the FDDA input. variable U_NDG_OLD contains standard...

  18. Does the size distribution of mineral dust aerosols depend on the wind speed at emission?

    Directory of Open Access Journals (Sweden)

    J. F. Kok

    2011-07-01

    Full Text Available The size distribution of mineral dust aerosols greatly affects their interactions with clouds, radiation, ecosystems, and other components of the Earth system. Several theoretical dust emission models predict that the dust size distribution depends on the wind speed at emission, with larger wind speeds predicted to produce smaller aerosols. The present study investigates this prediction using a compilation of published measurements of the size-resolved vertical dust flux emitted by eroding soils. Surprisingly, these measurements indicate that the size distribution of naturally emitted dust aerosols is independent of the wind speed. This finding is consistent with the recently formulated brittle fragmentation theory of dust emission, but inconsistent with other theoretical dust emission models. The independence of the emitted dust size distribution with wind speed simplifies both the parameterization of dust emission in atmospheric circulation models as well as the interpretation of geological records of dust deposition.

  19. Does the size distribution of mineral dust aerosols depend on the wind speed at emission?

    CERN Document Server

    Kok, Jasper F

    2011-01-01

    The size distribution of mineral dust aerosols partially determines their interactions with clouds, radiation, ecosystems, and other components of the Earth system. Several theoretical models predict that the dust size distribution depends on the wind speed at emission, with larger wind speeds predicted to produce smaller aerosols. The present study investigates this prediction using a compilation of published measurements of the size-resolved vertical dust flux emitted by eroding soils. Surprisingly, these measurements indicate that the size distribution of naturally emitted dust aerosols is independent of the wind speed. The recently formulated brittle fragmentation theory of dust emission is consistent with this finding, whereas other theoretical dust emission models are not. The independence of the emitted dust size distribution with wind speed simplifies both the interpretation of geological records of dust deposition and the parameterization of dust emission in atmospheric circulation models.

  20. Dynamic Performance of a Single Machine Brushless DFIG during Wind Speed Variation

    Directory of Open Access Journals (Sweden)

    Mona N. Eskander

    2015-07-01

    Full Text Available In this paper, the dynamic performance of the specially-designed Single Machine Brushless Doubly-Fed Induction Generator "SM-BDFIG" coupled to variable speed wind turbine is investigated. The rotor voltage of the SM-BDFIG during super-synchronous operation is used to charge a number of batteries, connected to the rotor via a 3- phase bridge rectifier. The number of charged battery cells are changed, by parallel and series connections, according to the wind speed variation, and consequently, the rotor voltage variation. The response of the stator, rotor, and DC link voltages and currents due to wind speed variations is presented. The electromagnetic torque, the stator active power, and the rotor active power during wind speed variations are also presented.

  1. Effect of wind speed and relative humidity on atmospheric dust concentrations in semi-arid climates.

    Science.gov (United States)

    Csavina, Janae; Field, Jason; Félix, Omar; Corral-Avitia, Alba Y; Sáez, A Eduardo; Betterton, Eric A

    2014-07-15

    Atmospheric particulate have deleterious impacts on human health. Predicting dust and aerosol emission and transport would be helpful to reduce harmful impacts but, despite numerous studies, prediction of dust events and contaminant transport in dust remains challenging. In this work, we show that relative humidity and wind speed are both determinants in atmospheric dust concentration. Observations of atmospheric dust concentrations in Green Valley, AZ, USA, and Juárez, Chihuahua, México, show that PM10 concentrations are not directly correlated with wind speed or relative humidity separately. However, selecting the data for high wind speeds (>4m/s at 10 m elevation), a definite trend is observed between dust concentration and relative humidity: dust concentration increases with relative humidity, reaching a maximum around 25% and it subsequently decreases with relative humidity. Models for dust storm forecasting may be improved by utilizing atmospheric humidity and wind speed as main drivers for dust generation and transport.

  2. Effect of Wind Speed and Relative Humidity on Atmospheric Dust Concentrations in Semi-Arid Climates

    Science.gov (United States)

    Csavina, Janae; Field, Jason; Félix, Omar; Corral-Avitia, Alba Y.; Sáez, A. Eduardo; Betterton, Eric A.

    2014-01-01

    Atmospheric particulate have deleterious impacts on human health. Predicting dust and aerosol emission and transport would be helpful to reduce harmful impacts but, despite numerous studies, prediction of dust events and contaminant transport in dust remains challenging. In this work, we show that relative humidity and wind speed are both determinants in atmospheric dust concentration. Observations of atmospheric dust concentrations in Green Valley, AZ, USA, and Juárez, Chihuahua, México, show that PM10 concentrations are not directly correlated with wind speed or relative humidity separately. However, selecting the data for high wind speeds (> 4 m/s at 10 m elevation), a definite trend is observed between dust concentration and relative humidity: dust concentration increases with relative humidity, reaching a maximum around 25% and it subsequently decreases with relative humidity. Models for dust storm forecasting may be improved by utilizing atmospheric humidity and wind speed as main drivers for dust generation and transport. PMID:24769193

  3. 40 CFR Table F-2 to Subpart F of... - Particle Sizes and Wind Speeds for Full Wind Tunnel Test, Wind Tunnel Inlet Aspiration Test, and...

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 5 2010-07-01 2010-07-01 false Particle Sizes and Wind Speeds for Full Wind Tunnel Test, Wind Tunnel Inlet Aspiration Test, and Static Chamber Test F Table F-2 to Subpart F... Characteristics of Class II Equivalent Methods for PM2.5 Pt. 53, Subpt. F, Table F-2 Table F-2 to Subpart F of...

  4. Wind Power - WINDSPD100_IN: Mean Wind Speed at Height of 100 Meters above Ground, Derived from Mesoscale Atmospheric Simulation System and WindMap (TrueWind Solutions, 200-Meter Grid)

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — The following is excerpted from an unpublished report by Michael Brower (2004): "Using the MesoMap system, TrueWind has produced maps of mean wind speed in Indiana...

  5. Wind Power - WINDSPD50_IN: Mean Wind Speed at Height of 50 Meters above Ground, Derived from Mesoscale Atmospheric Simulation System and WindMap (TrueWind Solutions, 200-Meter Grid)

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — The following is excerpted from an unpublished report by Michael Brower (2004): "Using the MesoMap system, TrueWind has produced maps of mean wind speed in Indiana...

  6. Numerical simulation of aerodynamic derivatives and critical wind speed for long-span bridges based on simplified steady wind field

    Science.gov (United States)

    Xin, Dabo; Ou, Jinping

    2007-06-01

    Combining the computational fluid dynamics-based numerical simulation with the forced vibration technique for extraction of aerodynamic derivatives, an approach for calculating the aerodynamic derivatives and the critical flutter wind speed for long-span bridges is presented in this paper. The RNG k-ɛ turbulent model is introduced to establish the governing equations, including the continuity equation and the Navier-Stokes equations, for solving the wind flow field around a two-dimensional bridge section. To illustrate the effectiveness and accuracy of the proposed approach, a simple application to the Hume Bridge in China is provided, and the numerical results show that the aerodynamic derivatives and the critical flutter wind speed obtained agree well with the wind tunnel test results.

  7. Numerical simulation of aerodynamic derivatives and critical wind speed for long-span bridges based on simplified steady wind field

    Institute of Scientific and Technical Information of China (English)

    Xin Dabo; Ou Jinping

    2007-01-01

    Combining the computational fluid dynamics-based numerical simulation with the forced vibration technique for extraction of aerodynamic derivatives, an approach for calculating the aerodynamic derivatives and the critical flutter wind speed for long-span bridges is presented in this paper. The RNG κ-ε turbulent model is introduced to establish the governing equations, including the continuity equation and the Navier-Stokes equations, for solving the wind flow field around a two-dimensional bridge section. To illustrate the effectiveness and accuracy of the proposed approach, a simple application to the Hume Bridge in China is provided, and the numerical results show that the aerodynamic derivatives and the critical flutter wind speed obtained agree well with the wind tunnel test results.

  8. LONG TERM WIND SPEED PREDICTION USING WAVELET COEFFICIENTS AND SOFT COMPUTING

    Directory of Open Access Journals (Sweden)

    Manju Khanna

    2016-10-01

    Full Text Available In the past researches, scholars have carried out short-term prediction for wind speed. The present work deals with long-term wind speed prediction, required for hybrid power generation design and contract planning. As the total database is quite large for long-term prediction, feature extraction of data by application of Lifting wavelet coefficients is exploited, along with soft computing techniques for time series data, which is scholastic in nature.

  9. LONG TERM WIND SPEED PREDICTION USING WAVELET COEFFICIENTS AND SOFT COMPUTING

    OpenAIRE

    Manju Khanna; Srinath, N. K; K. Mendiratta

    2016-01-01

    In the past researches, scholars have carried out short-term prediction for wind speed. The present work deals with long-term wind speed prediction, required for hybrid power generation design and contract planning. As the total database is quite large for long-term prediction, feature extraction of data by application of Lifting wavelet coefficients is exploited, along with soft computing techniques for time series data, which is scholastic in nature.

  10. A Hybrid Approach for Short-Term Forecasting of Wind Speed

    OpenAIRE

    Sivanagaraja Tatinati; Kalyana C. Veluvolu

    2013-01-01

    We propose a hybrid method for forecasting the wind speed. The wind speed data is first decomposed into intrinsic mode functions (IMFs) with empirical mode decomposition. Based on the partial autocorrelation factor of the individual IMFs, adaptive methods are then employed for the prediction of IMFs. Least squares-support vector machines are employed for IMFs with weak correlation factor, and autoregressive model with Kalman filter is employed for IMFs with high correlation factor. Multistep ...

  11. Comparison of Wind Power Converter Reliability with Low-Speed and Medium-Speed Permanent-Magnet Synchronous Generators

    DEFF Research Database (Denmark)

    Zhou, Dao; Blaabjerg, Frede; Franke, Toke

    2015-01-01

    of the low-speed (direct-drive) and medium-speed (one-stage) permanent-magnet synchronous generators are both promising solutions. This paper will assess and compare the reliability metrics for the machine-side converter for those two configurations. First, a translation from the mission profile......, according to the lifetime power cycles, the lifespan can be calculated when operating in various wind classes. It is concluded that, although the low-speed permanent-magnet synchronous generator is able to eliminate the gearbox, the lifespan of its machine-side converter is lower than the one-stage medium...

  12. 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......, the analytical models include the wind turbine power characteristics; the single/threestage gearbox and the power electronic converter for possible wind turbine concepts are described. Finally, the electromagnetic design models of the investigated generator topologies are presented, including the squirrel cage...... induction generator (SCIG), the doubly-fed induction generator (DFIG), the electrically excited synchronous generator (EESG) and permanent magnet synchronous generator (PMSG). Numerical evaluation with optimized design and comparison of variable speed wind generator systems by using the presented models...

  13. Estimation of the high-spatial-resolution variability in extreme wind speeds for forestry applications

    Science.gov (United States)

    Venäläinen, Ari; Laapas, Mikko; Pirinen, Pentti; Horttanainen, Matti; Hyvönen, Reijo; Lehtonen, Ilari; Junila, Päivi; Hou, Meiting; Peltola, Heli M.

    2017-07-01

    The bioeconomy has an increasing role to play in climate change mitigation and the sustainable development of national economies. In Finland, a forested country, over 50 % of the current bioeconomy relies on the sustainable management and utilization of forest resources. Wind storms are a major risk that forests are exposed to and high-spatial-resolution analysis of the most vulnerable locations can produce risk assessment of forest management planning. In this paper, we examine the feasibility of the wind multiplier approach for downscaling of maximum wind speed, using 20 m spatial resolution CORINE land-use dataset and high-resolution digital elevation data. A coarse spatial resolution estimate of the 10-year return level of maximum wind speed was obtained from the ERA-Interim reanalyzed data. Using a geospatial re-mapping technique the data were downscaled to 26 meteorological station locations to represent very diverse environments. Applying a comparison, we find that the downscaled 10-year return levels represent 66 % of the observed variation among the stations examined. In addition, the spatial variation in wind-multiplier-downscaled 10-year return level wind was compared with the WAsP model-simulated wind. The heterogeneous test area was situated in northern Finland, and it was found that the major features of the spatial variation were similar, but in some locations, there were relatively large differences. The results indicate that the wind multiplier method offers a pragmatic and computationally feasible tool for identifying at a high spatial resolution those locations with the highest forest wind damage risks. It can also be used to provide the necessary wind climate information for wind damage risk model calculations, thus making it possible to estimate the probability of predicted threshold wind speeds for wind damage and consequently the probability (and amount) of wind damage for certain forest stand configurations.

  14. The Impacts of Atmospheric Stability on the Accuracy of Wind Speed Extrapolation Methods

    Directory of Open Access Journals (Sweden)

    Jennifer F. Newman

    2014-01-01

    Full Text Available The building of utility-scale wind farms requires knowledge of the wind speed climatology at hub height (typically 80–100 m. As most wind speed measurements are taken at 10 m above ground level, efforts are being made to relate 10-m measurements to approximate hub-height wind speeds. One common extrapolation method is the power law, which uses a shear parameter to estimate the wind shear between a reference height and hub height. The shear parameter is dependent on atmospheric stability and should ideally be determined independently for different atmospheric stability regimes. In this paper, data from the Oklahoma Mesonet are used to classify atmospheric stability and to develop stability-dependent power law fits for a nearby tall tower. Shear exponents developed from one month of data are applied to data from different seasons to determine the robustness of the power law method. In addition, similarity theory-based methods are investigated as possible alternatives to the power law. Results indicate that the power law method performs better than similarity theory methods, particularly under stable conditions, and can easily be applied to wind speed data from different seasons. In addition, the importance of using co-located near-surface and hub-height wind speed measurements to develop extrapolation fits is highlighted.

  15. Prediction of wind speed time series using modified Taylor Kriging method

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Heping; Shi, Jing; Erdem, Ergin [Department of Industrial and Manufacturing Engineering, North Dakota State University, Dept 2485, PO Box 6050, Fargo, ND 58108 (United States)

    2010-12-15

    Wind speed forecasting is critical for the operations of wind turbine and penetration of wind energy into electricity systems. In this paper, a novel time series forecasting method is proposed for this purpose. This method originates from TK (Taylor Kriging) model, but is properly modified for the forecasting of wind speed time series. To investigate the performance of this new method, the wind speed data from an observation site in North Dakota, USA, are adopted. One-year hourly wind speed data are divided into 10 samples, and forecast is made for each sample. In the case study, both the modified TK method and (ARIMA) autoregressive integrated moving average method are employed and their performances are compared. It is found that on average, the proposed method outperforms the ARIMA method by 18.60% and 15.23% in terms of (MAE) mean absolute error and (RMSE) root mean square error. Meanwhile, further theoretical analysis is provided to discuss why the modified TK method is potentially more accurate than the ARIMA method for wind speed time series prediction. (author)

  16. Influence of Wind Speed on RGB-D Images in Tree Plantations

    Directory of Open Access Journals (Sweden)

    Dionisio Andújar

    2017-04-01

    Full Text Available Weather conditions can affect sensors’ readings when sampling outdoors. Although sensors are usually set up covering a wide range of conditions, their operational range must be established. In recent years, depth cameras have been shown as a promising tool for plant phenotyping and other related uses. However, the use of these devices is still challenged by prevailing field conditions. Although the influence of lighting conditions on the performance of these cameras has already been established, the effect of wind is still unknown. This study establishes the associated errors when modeling some tree characteristics at different wind speeds. A system using a Kinect v2 sensor and a custom software was tested from null wind speed up to 10 m·s−1. Two tree species with contrasting architecture, poplars and plums, were used as model plants. The results showed different responses depending on tree species and wind speed. Estimations of Leaf Area (LA and tree volume were generally more consistent at high wind speeds in plum trees. Poplars were particularly affected by wind speeds higher than 5 m·s−1. On the contrary, height measurements were more consistent for poplars than for plum trees. These results show that the use of depth cameras for tree characterization must take into consideration wind conditions in the field. In general, 5 m·s−1 (18 km·h−1 could be established as a conservative limit for good estimations.

  17. Reduction of the performance of a noise screen due to screen-induced wind-speed gradients: numerical computations and wind-tunnel experiments

    NARCIS (Netherlands)

    Salomons, E.M.

    1999-01-01

    Downwind sound propagation over a noise screen is investigated by numerical computations and scale model experiments in a wind tunnel. For the computations, the parabolic equation method is used, with a range-dependent sound-speed profile based on wind-speed profiles measured in the wind tunnel and

  18. Reduction of the performance of a noise screen due to screen-induced wind-speed gradients: numerical computations and wind-tunnel experiments

    NARCIS (Netherlands)

    Salomons, E.M.

    1999-01-01

    Downwind sound propagation over a noise screen is investigated by numerical computations and scale model experiments in a wind tunnel. For the computations, the parabolic equation method is used, with a range-dependent sound-speed profile based on wind-speed profiles measured in the wind tunnel and

  19. Power Control of Permanent Magnet Generator Based Variable Speed Wind Turbines

    DEFF Research Database (Denmark)

    Deng, Fujin; Chen, Zhe

    2009-01-01

    When the wind power accounts for a large portion of the grid, it will be required to regulate the active power and reactive power. This paper investigates a MWlevel variable speed wind turbine with a permanent magnet synchronous generator (PMSG). The power control capabilities of two kinds...

  20. A New Structure Based on Cascaded Multilevel Converter for Variable Speed Wind Turbine

    DEFF Research Database (Denmark)

    Deng, Fujin; Chen, Zhe

    2010-01-01

    An alternative structure for variable speed wind turbine, using multiple permanent magnet synchronous generators (PMSGs) drive-train configuration and cascaded multilevel converter is proposed in this paper. This study presents a power electronic solution for the wind turbine. A transformer...

  1. Ensemble Nonlinear Autoregressive Exogenous Artificial Neural Networks for Short-Term Wind Speed and Power Forecasting.

    Science.gov (United States)

    Men, Zhongxian; Yee, Eugene; Lien, Fue-Sang; Yang, Zhiling; Liu, Yongqian

    2014-01-01

    Short-term wind speed and wind power forecasts (for a 72 h period) are obtained using a nonlinear autoregressive exogenous artificial neural network (ANN) methodology which incorporates either numerical weather prediction or high-resolution computational fluid dynamics wind field information as an exogenous input. An ensemble approach is used to combine the predictions from many candidate ANNs in order to provide improved forecasts for wind speed and power, along with the associated uncertainties in these forecasts. More specifically, the ensemble ANN is used to quantify the uncertainties arising from the network weight initialization and from the unknown structure of the ANN. All members forming the ensemble of neural networks were trained using an efficient particle swarm optimization algorithm. The results of the proposed methodology are validated using wind speed and wind power data obtained from an operational wind farm located in Northern China. The assessment demonstrates that this methodology for wind speed and power forecasting generally provides an improvement in predictive skills when compared to the practice of using an "optimal" weight vector from a single ANN while providing additional information in the form of prediction uncertainty bounds.

  2. Dynamic Analysis of Fluid Power Drive-trains for Variable Speed Wind Turbines: a Parameter Study

    NARCIS (Netherlands)

    Jarquin Laguna, A.; Diepeveen, N.F.B.

    2013-01-01

    In the pursuit of making wind energy technology more economically attractive, the application of fluid power technology for the transmission of wind energy is being developed by several parties all over the world. This paper presents a dynamic model of a fluid power transmission for variable speed w

  3. Seasonal variation of Sigma sub(Theta) with wind speed, direction and stability

    Digital Repository Service at National Institute of Oceanography (India)

    Sadhuram, Y.

    For an airport site near Visakhapatnam, India, and based on 10 years of data for the months of January, April, August and October, values of Sigma sub(Theta) are given as a function of wind speed, wind direction and Pasquill diffusion category...

  4. How well can we measure the vertical wind speed? Implications for fluxes of energy and mass

    Science.gov (United States)

    John Kochendorfer; Tilden P. Meyers; John Frank; William J. Massman; Mark W. Heuer

    2012-01-01

    Sonic anemometers are capable of measuring the wind speed in all three dimensions at high frequencies (10­50 Hz), and are relied upon to estimate eddy-covariance-based fluxes of mass and energy over a wide variety of surfaces and ecosystems. In this study, wind-velocity measurement errors from a three-dimensional sonic anemometer with a nonorthogonal transducer...

  5. Low Voltage Ride-Through of Variable Speed Wind Turbines with Permanent Magnet Synchronous Generator

    DEFF Research Database (Denmark)

    Hu, Weihao; Chen, Zhe; Wang, Yue

    2009-01-01

    This paper presents a simulation model of a MW-level variable speed wind turbine with a permanent magnet synchronous generator (PMSG) and a full-scale converter developed in the simulation tool of PSCAD/EMTDC. The low voltage ride-through (LVRT) capability of the wind turbine is investigated. A n...

  6. Dynamic Analysis of Fluid Power Drive-trains for Variable Speed Wind Turbines: a Parameter Study

    NARCIS (Netherlands)

    Jarquin Laguna, A.; Diepeveen, N.F.B.

    2013-01-01

    In the pursuit of making wind energy technology more economically attractive, the application of fluid power technology for the transmission of wind energy is being developed by several parties all over the world. This paper presents a dynamic model of a fluid power transmission for variable speed w

  7. Modeling and Operational Testing of an Isolated Variable Speed PMSG Wind Turbine with Battery Energy Storage

    OpenAIRE

    BAROTE, L.; MARINESCU, C.

    2012-01-01

    This paper presents the modeling and operational testing of an isolated permanent magnet synchronous generator (PMSG), driven by a small wind turbine with a battery energy storage system during wind speed and load variations. The whole system is initially modeled, including the PMSG, the boost converter and the storage system. The required power for the connected loads can be effectively delivered and supplied by the proposed wind turbine and energy storage systems, subject to an appropri...

  8. The Mathematical Representation of Wind Speed and Temperature Profiles in the Unstable Atmospheric Surface Layer

    DEFF Research Database (Denmark)

    Paulson, C.A.

    1970-01-01

    Analytical expressions which specify non-dimensionalized wind speed and potential temperature gradients as functions of stability are integrated. The integrated equations are tested against Swinhank's wind and temperature profiles measured at Kerang, Australia. It is found that a representation s...... suggested independently by Businger and by Dyer gives the best fit to temperature profiles and describes the wind profiles equally as well as a relation suggested by Panofsky et al....

  9. Changes in Surface Wind Speed over North America from CMIP5 Model Projections and Implications for Wind Energy

    OpenAIRE

    Sujay Kulkarni; Huei-Ping Huang

    2014-01-01

    The centennial trends in the surface wind speed over North America are deduced from global climate model simulations in the Climate Model Intercomparison Project—Phase 5 (CMIP5) archive. Using the 21st century simulations under the RCP 8.5 scenario of greenhouse gas emissions, 5–10 percent increases per century in the 10 m wind speed are found over Central and East-Central United States, the Californian Coast, and the South and East Coasts of the USA in winter. In summer, climate models proje...

  10. Calibration of a spinner anemometer for wind speed measurements

    OpenAIRE

    Demurtas, Giorgio; Friis Pedersen, Troels; Zahle, Frederik

    2016-01-01

    The power curve of a wind turbine can be measured, according to IEC 61400-12-2 with a nacelle-mounted anemometer. Typically, a sonic anemometer or a cup anemometer and a wind vane are mounted on the back of the nacelle roof. Another option is to use a spinner anemometer. The measurement principle of the spinner anemometer is based on the flow distortion caused by the wind turbine spinner. The flow on the spinner surface is measured by means of three 1D sonic sensors mounted on the spinner and...

  11. Damage tolerance and structural monitoring for wind turbine blades.

    Science.gov (United States)

    McGugan, M; Pereira, G; Sørensen, B F; Toftegaard, H; Branner, K

    2015-02-28

    The paper proposes a methodology for reliable design and maintenance of wind turbine rotor blades using a condition monitoring approach and a damage tolerance index coupling the material and structure. By improving the understanding of material properties that control damage propagation it will be possible to combine damage tolerant structural design, monitoring systems, inspection techniques and modelling to manage the life cycle of the structures. This will allow an efficient operation of the wind turbine in terms of load alleviation, limited maintenance and repair leading to a more effective exploitation of offshore wind.

  12. Damage tolerance and structural monitoring for wind turbine blades

    Science.gov (United States)

    McGugan, M.; Pereira, G.; Sørensen, B. F.; Toftegaard, H.; Branner, K.

    2015-01-01

    The paper proposes a methodology for reliable design and maintenance of wind turbine rotor blades using a condition monitoring approach and a damage tolerance index coupling the material and structure. By improving the understanding of material properties that control damage propagation it will be possible to combine damage tolerant structural design, monitoring systems, inspection techniques and modelling to manage the life cycle of the structures. This will allow an efficient operation of the wind turbine in terms of load alleviation, limited maintenance and repair leading to a more effective exploitation of offshore wind. PMID:25583858

  13. China's Wind Power: Going Forward with Lightening Speed

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Not long ago, CREIA (Chinese Renewable Energy Industries Association) and Greenpeace, one of the international environmentalprotection organizations, announced that China has become the world's largest country of wind power capacity. According to another report, Chinese wind power companies, such as Goldwind Technology, Dongfang Electric and oth- ers are actively "going out" to expand their market territory. From the manufacture of

  14. Wind turbine condition monitoring based on SCADA data using normal behavior models

    DEFF Research Database (Denmark)

    Schlechtingen, Meik; Santos, Ilmar; Achiche, Sofiane

    2013-01-01

    This paper proposes a system for wind turbine condition monitoring using Adaptive Neuro-Fuzzy Interference Systems (ANFIS). For this purpose: (1) ANFIS normal behavior models for common Supervisory Control And Data Acquisition (SCADA) data are developed in order to detect abnormal behavior....... The applicability of the set up ANFIS models for anomaly detection is proved by the achieved performance of the models. In combination with the FIS the prediction errors can provide information about the condition of the monitored components. In this paper the condition monitoring system is described. Part two...... the applicability of ANFIS models for monitoring wind turbine SCADA signals. The computational time needed for model training is compared to Neural Network (NN) models showing the strength of ANFIS in training speed. (2) For automation of fault diagnosis Fuzzy Interference Systems (FIS) are used to analyze...

  15. Fault diagnosis and condition monitoring of wind turbines

    DEFF Research Database (Denmark)

    Niemann, Hans Henrik; Poulsen, Niels Kjølstad; Mirzaei, Mahmood

    2017-01-01

    standard sensors on modern wind turbines, including moment sensors and rotor angle sensors. This approach will allow the method to be applied to existing wind turbines without any modifications. The method is based on the detection of asymmetries in the rotor system caused by changes or faults in the rotor......This paper describes a model-free method for the fault diagnosis and condition monitoring of rotor systems in wind turbines. Both fault diagnosis and monitoring can be achieved without using a model for the wind turbine, applied controller, or wind profiles. The method is based on measurements from...... and phase information of the modulation signals. It is possible to detect and isolate which blade is faulty or has been changed based on these signatures. Furthermore, the faulty component can be isolated, ie, the actuator, sensor or blade, and the type of fault can be determined. The method can be used...

  16. Experimental Testing of a Generic Submarine Model in the DSTO Low Speed Wind Tunnel. Phase 2

    Science.gov (United States)

    2014-03-01

    Defence Science and Technology Organisation Technical Report DSTO-TR-1622, 2004. [3] Barlow, J. B., Rae , W. H. and Pope, A., Low-Speed Wind Tunnel...kW (900 hp) electric motor driving a 3.96 m diameter eight bladed fan, with a maximum rotational speed 750 RPM, manually controlled. Cooling 40 °C

  17. Improving transition between power optimization and power limitation of variable speed/variable pitch wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, A.D.; Bindner, H. [Risoe National Lab., Wind Energy and Atmospheric Physics Dept., Roskilde (Denmark); Rebsdorf, A. [Vestas Wind Systems A/S, Lem (Denmark)

    1999-03-01

    The paper summarises and describes the main results of a recently performed study of improving the transition between power optimization and power limitation for variable speed/variable pitch wind turbines. The results show that the capability of varying the generator speed also can be exploited in the transition stage to improve the quality of the generated power. (au)

  18. Variable Speed Wind Turbine Based on Multiple Generators Drive-Train Configuration

    DEFF Research Database (Denmark)

    Deng, Fujin; Chen, Zhe

    2010-01-01

    A variable speed wind turbine is presented in this paper, where multiple permanent magnet synchronous generators (MPMSGs) drive-train configuration is employed in the wind turbine. A cascaded multilevel converter interface based on the MPMSGs is developed to synthesize a desired high ac sinusoidal...... reduce the fluctuation of the electromagnetic torque sum and results in a good performance for the MPMSGs structure. The simulation study is conducted using PSCAD/EMTDC, and the results verify the feasibility of this variable speed wind turbine based on multiple generators drive-train configuration....

  19. Retrieval of Wind Speed Using an L-band Synthetic Aperture Radar

    DEFF Research Database (Denmark)

    Monaldo, Frank M.; Thompson, Donald R.; Badger, Merete

    2007-01-01

    Retrieval of wind speed using L-band synthetic aperture radar (SAR) is both an old and new endeavor. Although the Seasat L-band SAR in 1978 was not well calibrated, early results indicated a strong relationship between observed SAR image intensity and wind speed. The JERS-1 L-band SAR had limited...... usefulness over the ocean. Most recent wind retrievals from spaceborne SARs have been at C-band for ERS-1/2, Radarsat, and Envisat. With the launch of the sophisticated multi- polarization Phased Array L-band Synthetic Aperture Radar (PALSAR) on the Advanced Land Observing Satellite (ALOS), we renew...

  20. Short term forecasting of surface layer wind speed using a continuous cascade model

    CERN Document Server

    Baile, Rachel; Poggi, Philippe

    2010-01-01

    This paper describes a statistical method for short-term forecasting of surface layer wind velocity amplitude relying on the notion of continuous cascades. Inspired by recent empirical findings that suggest the existence of some cascading process in the mesoscale range, we consider that wind speed can be described by a seasonal component and a fluctuating part represented by a "multifractal noise" associated with a random cascade. Performances of our model are tested on hourly wind speed series gathered at various locations in Corsica (France) and Netherlands. The obtained results show a systematic improvement of the prediction as compared to reference models like persistence or Artificial Neural Networks.

  1. Wind speed and direction predictions by WRF and WindSim coupling over Nygårdsfjell

    Science.gov (United States)

    Bilal, M.; Solbakken, K.; Birkelund, Y.

    2016-09-01

    In this study, the performance of the mesoscale meteorological Weather Research and Forecast (WRF) model coupled with the microscale computational fluid dynamics based model WindSim is investigated and compared to the performance of WRF alone. The two model set-ups, WRF and WRF-WindSim, have been tested on three high-wind events in February, June and October, over a complex terrain at the Nygårdsfjell wind park in Norway. The wind speeds and wind directions are compared to measurements and the results are evaluated based on root mean square error, bias and standard deviation error. Both model set-ups are able to reproduce the high wind events. For the winter month February the WRF-WindSim performed better than WRF alone, with the root mean square error (RMSE) decreasing from 2.86 to 2.38 and standard deviation error (STDE) decreasing from 2.69 to 2.37. For the two other months no such improvements were found. The best model performance was found in October where the WRF had a RMSE of 1.76 and STDE of 1.68. For June, both model set-ups underestimate the wind speed. Overall, the adopted coupling method of using WRF outputs as virtual climatology for coupling WRF and WindSim did not offer a significant improvement over the complex terrain of Nygårdsfjell. However, the proposed coupling method offers high degree of simplicity when it comes to its application. Further testing is recommended over larger number of test cases to make a significant conclusion.

  2. The Distribution of Solar Wind Speeds During Solar Minimum: Calibration for Numerical Solar Wind Modeling Constraints on the Source of the Slow Solar Wind (Postprint)

    Science.gov (United States)

    2012-03-05

    2003) and Schwadron et al. (2005) as constraints. The new relationship was tested by using it to drive the ENLIL 3‐D MHD solar wind model and obtain...it to drive the ENLIL 3‐D MHD solar wind model and obtain solar wind parameters at Earth (1.0 AU) and Ulysses (1.4 AU). The improvements in speed...propagated out into the heliosphere using the ENLIL solar wind model . ENLIL is a 3‐D Magne- tohydrodynamic ( MHD ) model of the heliosphere [Odstrcil, 2003

  3. Stochastic modeling and performance monitoring of wind farm power production

    CERN Document Server

    Milan, Patrick; Peinke, Joachim

    2015-01-01

    We present a new stochastic approach to describe and remodel the conversion process of a wind farm at a sampling frequency of 1Hz. When conditioning on various wind direction sectors, the dynamics of the conversion process appear as a fluctuating trajectory around an average IEC-like power curve, see section II. Our approach is to consider the wind farm as a dynamical system that can be described as a stochastic drift/diffusion model, where a drift coefficient describes the attraction towards the power curve and a diffusion coefficient quantifies additional turbulent fluctuations. These stochastic coefficients are inserted into a Langevin equation that, once properly adapted to our particular system, models a synthetic signal of power output for any given wind speed/direction signals, see section III. When combined with a pre-model for turbulent wind fluctuations, the stochastic approach models the power output of the wind farm at a sampling frequency of 1Hz using only ten-minute average values of wind speed ...

  4. Space-time wind speed forecasting for improved power system dispatch

    KAUST Repository

    Zhu, Xinxin

    2014-02-27

    To support large-scale integration of wind power into electric energy systems, state-of-the-art wind speed forecasting methods should be able to provide accurate and adequate information to enable efficient, reliable, and cost-effective scheduling of wind power. Here, we incorporate space-time wind forecasts into electric power system scheduling. First, we propose a modified regime-switching, space-time wind speed forecasting model that allows the forecast regimes to vary with the dominant wind direction and with the seasons, hence avoiding a subjective choice of regimes. Then, results from the wind forecasts are incorporated into a power system economic dispatch model, the cost of which is used as a loss measure of the quality of the forecast models. This, in turn, leads to cost-effective scheduling of system-wide wind generation. Potential economic benefits arise from the system-wide generation of cost savings and from the ancillary service cost savings. We illustrate the economic benefits using a test system in the northwest region of the United States. Compared with persistence and autoregressive models, our model suggests that cost savings from integration of wind power could be on the scale of tens of millions of dollars annually in regions with high wind penetration, such as Texas and the Pacific northwest. © 2014 Sociedad de Estadística e Investigación Operativa.

  5. Wind Turbine Tower Vibration Modeling and Monitoring by the Nonlinear State Estimation Technique (NSET

    Directory of Open Access Journals (Sweden)

    Peng Guo

    2012-12-01

    Full Text Available With appropriate vibration modeling and analysis the incipient failure of key components such as the tower, drive train and rotor of a large wind turbine can be detected. In this paper, the Nonlinear State Estimation Technique (NSET has been applied to model turbine tower vibration to good effect, providing an understanding of the tower vibration dynamic characteristics and the main factors influencing these. The developed tower vibration model comprises two different parts: a sub-model used for below rated wind speed; and another for above rated wind speed. Supervisory control and data acquisition system (SCADA data from a single wind turbine collected from March to April 2006 is used in the modeling. Model validation has been subsequently undertaken and is presented. This research has demonstrated the effectiveness of the NSET approach to tower vibration; in particular its conceptual simplicity, clear physical interpretation and high accuracy. The developed and validated tower vibration model was then used to successfully detect blade angle asymmetry that is a common fault that should be remedied promptly to improve turbine performance and limit fatigue damage. The work also shows that condition monitoring is improved significantly if the information from the vibration signals is complemented by analysis of other relevant SCADA data such as power performance, wind speed, and rotor loads.

  6. Wind speed forecasting in three different regions of Mexico, using a hybrid ARIMA-ANN model

    Energy Technology Data Exchange (ETDEWEB)

    Cadenas, Erasmo [Facultad de Ingenieria Mecanica, Universidad Michoacana de San Nicolas de Hidalgo, Santiago Tapia No. 403, Centro (Mexico); Rivera, Wilfrido [Centro de Ivestigacion en Energia, Universidad Nacional Autonoma de Mexico, Apartado Postal 34, Temixco 62580, Morelos (Mexico)

    2010-12-15

    In this paper the wind speed forecasting in the Isla de Cedros in Baja California, in the Cerro de la Virgen in Zacatecas and in Holbox in Quintana Roo is presented. The time series utilized are average hourly wind speed data obtained directly from the measurements realized in the different sites during about one month. In order to do wind speed forecasting Hybrid models consisting of Autoregressive Integrated Moving Average (ARIMA) models and Artificial Neural Network (ANN) models were developed. The ARIMA models were first used to do the wind speed forecasting of the time series and then with the obtained errors ANN were built taking into account the nonlinear tendencies that the ARIMA technique could not identify, reducing with this the final errors. Once the Hybrid models were developed 48 data out of sample for each one of the sites were used to do the wind speed forecasting and the results were compared with the ARIMA and the ANN models working separately. Statistical error measures such as the mean error (ME), the mean square error (MSE) and the mean absolute error (MAE) were calculated to compare the three methods. The results showed that the Hybrid models predict the wind velocities with a higher accuracy than the ARIMA and ANN models in the three examined sites. (author)

  7. Flicker Study on Variable Speed Wind Turbines with Permanent Magnet Synchronous Generator

    DEFF Research Database (Denmark)

    Hu, Weihao; Chen, Zhe; Wang, Yue

    2008-01-01

    Grid connected wind turbines are fluctuating power sources that may produce flicker during continuous operation. This paper presents a simulation model of a MW-level variable speed wind turbines with a permanent magnet synchronous generator (PMSG) and a full-scale converter developed in the simul......Grid connected wind turbines are fluctuating power sources that may produce flicker during continuous operation. This paper presents a simulation model of a MW-level variable speed wind turbines with a permanent magnet synchronous generator (PMSG) and a full-scale converter developed...... in the simulation tool of PSCAD/EMTDC. Flicker emission of this system is investigated during continuous operation. The dependence of flicker emission on wind characteristics (mean speed, turbulence intensity), 3p torque oscillations due to wind shear and tower shadow effects and grid conditions (short circuit...... capacity, grid impedance angle) are analyzed. Flicker mitigation is realized by output reactive power control of the variable speed wind turbines with PMSG. Simulation results show the output reactive power control is an effective measure to mitigate the flicker during continuous operation of grid...

  8. Short-Term Wind Speed Forecasting Using Support Vector Regression Optimized by Cuckoo Optimization Algorithm

    Directory of Open Access Journals (Sweden)

    Jianzhou Wang

    2015-01-01

    Full Text Available This paper develops an effectively intelligent model to forecast short-term wind speed series. A hybrid forecasting technique is proposed based on recurrence plot (RP and optimized support vector regression (SVR. Wind caused by the interaction of meteorological systems makes itself extremely unsteady and difficult to forecast. To understand the wind system, the wind speed series is analyzed using RP. Then, the SVR model is employed to forecast wind speed, in which the input variables are selected by RP, and two crucial parameters, including the penalties factor and gamma of the kernel function RBF, are optimized by various optimization algorithms. Those optimized algorithms are genetic algorithm (GA, particle swarm optimization algorithm (PSO, and cuckoo optimization algorithm (COA. Finally, the optimized SVR models, including COA-SVR, PSO-SVR, and GA-SVR, are evaluated based on some criteria and a hypothesis test. The experimental results show that (1 analysis of RP reveals that wind speed has short-term predictability on a short-term time scale, (2 the performance of the COA-SVR model is superior to that of the PSO-SVR and GA-SVR methods, especially for the jumping samplings, and (3 the COA-SVR method is statistically robust in multi-step-ahead prediction and can be applied to practical wind farm applications.

  9. Gusts detection in a horizontal wind turbine by monitoring of innovations error of an extended Kalman filter

    Science.gov (United States)

    Recalde, L. F.; Hur, S.; Leithead, W. E.

    2016-09-01

    This paper presents a novel model-based detection scheme capable of detecting and diagnosing gusts. Detection is achieved by monitoring the innovations error (i.e., the difference between the estimated and measured outputs) of an extended discrete Kalman filter. It is designed to trigger a detection/confirmation alarm in the presence of wind anomalies. Simulation results are presented to demonstrate that both operating and coherent extreme wind gusts can successfully be detected. The wind anomaly is identified in magnitude and shape through maximum likelihood ratio and goodness of fit, respectively. The detector is capable of isolating extreme wind gusts before the turbine over speeds.

  10. Application of Surface Protective Coating to Enhance Environment-Withstanding Property of the MEMS 2D Wind Direction and Wind Speed Sensor

    National Research Council Canada - National Science Library

    Kyu-Sik Shin; Dae-Sung Lee; Sang-Woo Song; Jae Pil Jung

    2017-01-01

    In this study, a microelectromechanical system (MEMS) two-dimensional (2D) wind direction and wind speed sensor consisting of a square heating source and four thermopiles was manufactured using the heat detection method...

  11. Robust Active Disturbance Rejection Control Approach to Maximize Energy Capture in Variable-Speed Wind Turbines

    OpenAIRE

    Horacio Coral-Enriquez; John Cortés-Romero; Germán A. Ramos

    2013-01-01

    This paper proposes an alternative robust observer-based linear control technique to maximize energy capture in a 4.8 MW horizontal-axis variable-speed wind turbine. The proposed strategy uses a generalized proportional integral (GPI) observer to reconstruct the aerodynamic torque in order to obtain a generator speed optimal trajectory. Then, a robust GPI observer-based controller supported by an active disturbance rejection (ADR) approach allows asymptotic tracking of the generator speed opt...

  12. Comparative study of speed estimators with highly noisymeasurement signals for Wind Energy Generation Systems

    OpenAIRE

    Carranza Castillo, Oscar; Figueres Amorós, Emilio; Garcerá Sanfeliú, Gabriel; GONZÁLEZ MORALES, LUIS GERARDO

    2011-01-01

    This paper presents a comparative study of several speed estimators to implement a sensorless speed control loop in Wind Energy Generation Systems driven by power factor correction three-phase boost rectifiers. This rectifier topology reduces the low frequency harmonics contents of the generator currents and, consequently, the generator power factor approaches unity whereas undesired vibrations of the mechanical system decrease. For implementation of the speed estimators, the compared techniq...

  13. LIDAR wind speed measurements from a rotating spinner (SpinnerEx 2009)

    Energy Technology Data Exchange (ETDEWEB)

    Angelou, N.; Mikkelsen, Torben; Hansen, Kasper H.; Sjoeholm, M.; Harris, M.

    2010-08-15

    In the context of the increasing application of remote sensing techniques in wind energy, the feasibility of upwind observations via a spinner-mounted wind lidar was tested during the SpinnerEx 2009 experiment. The objective was to install a QinetiQ (Natural Power) ZephIR lidar in the rotating spinner of a MW-sized wind turbine, and investigate the approaching wind fields from this vantage point. Time series of wind speed measurements from the lidar with 50 Hz sampling rate were successfully obtained for approximately 60 days, during the measurement campaign lasting from April to August 2009. In this report, information is given regarding the experimental setup and the lidar's operation parameters. The geometrical model used for the reconstruction of the scanning pattern of the lidar is described. This model takes into account the lidar's pointing direction, the spinner axis's vertical tilt and the wind turbine's yaw relative to the mean wind speed direction. The data analysis processes are documented. A methodology for the calculation of the yaw misalignment of the wind turbine relative to the wind direction, as a function of various averaging times, is proposed, using the lidar's instantaneous line-of-sight radial wind speed measurements. Two different setups have been investigated in which the approaching wind field was measured at distances of 0.58 OE and 1.24 OE rotor diameters upwind, respectively. For both setups, the instantaneous yaw misalignment of the turbine has been estimated from the lidar measurements. Data from an adjacent meteorological mast as well as data logged within the wind turbine's control system were used to evaluate the results. (author)

  14. Hybrid Short Term Wind Speed Forecasting Using Variational Mode Decomposition and a Weighted Regularized Extreme Learning Machine

    Directory of Open Access Journals (Sweden)

    Nantian Huang

    2016-11-01

    Full Text Available Accurate wind speed forecasting is a fundamental element of wind power prediction. Thus, a new hybrid wind speed forecasting model, using variational mode decomposition (VMD, the partial autocorrelation function (PACF, and weighted regularized extreme learning machine (WRELM, is proposed to improve the accuracy of wind speed forecasting. First, the historic wind speed time series is decomposed into several intrinsic mode functions (IMFs. Second, the partial correlation of each IMF sequence is analyzed using PACF to select the optimal subfeature set for particular predictors of each IMF. Then, the predictors of each IMF are constructed in order to enhance its strength using WRELM. Finally, wind speed is obtained by adding up all the predictors. The experiment, using real wind speed data, verified the effectiveness and advancement of the new approach.

  15. Analysis of vertical wind direction and speed gradients for data from the met. mast at Hoevsoere

    Energy Technology Data Exchange (ETDEWEB)

    Cariou, N.; Wagner, R.; Gottschall, J.

    2010-05-15

    The task of this project has been to study the vertical gradient of the wind direction from experimental data obtained with different measurement instruments at the Hoevsoere test site, located at the west coast of Denmark. The major part of the study was based on data measured by wind vanes mounted at a meteorological (met.) mast. These measurements enabled us to make an analysis of the variation of the direction with altitude, i.e. the wind direction shear. For this purpose, four years of wind direction measurements at two heights (60 m and 100 m) were analysed with special respect to the diurnal and seasonal variations of the direction gradient. The location of the test site close to the sea allowed for an investigation of specific trends for offshore and onshore winds, dependent on the considered wind direction sector. Furthermore, a comparison to lidar measurements showed the existence of an offset between the two vanes used for the analysis, which has to be considered for evaluating the significance and uncertainty of the results. Finally, the direction shear was analysed as function of wind speed and compared to the corresponding relation for the wind speed shear. Our observation from this is that the direction shear does not necessarily increase with the speed shear. (author)

  16. Aerodynamical errors on tower mounted wind speed measurements due to the presence of the tower

    Energy Technology Data Exchange (ETDEWEB)

    Bergstroem, H. [Uppsala Univ. (Sweden). Dept. of Meteorology; Dahlberg, J.Aa. [Aeronautical Research Inst. of Sweden, Bromma (Sweden)

    1996-12-01

    Field measurements of wind speed from two lattice towers showed large differences for wind directions where the anemometers of both towers should be unaffected by any upstream obstacle. The wind speed was measured by cup anemometers mounted on booms along the side of the tower. A simple wind tunnel test indicates that the boom, for the studied conditions, could cause minor flow disturbances. A theoretical study, by means of simple 2D flow modelling of the flow around the mast, demonstrates that the tower itself could cause large wind flow disturbances. A theoretical study, based on simple treatment of the physics of motion of a cup anemometer, demonstrates that a cup anemometer is sensitive to velocity gradients across the cups and responds clearly to velocity gradients in the vicinity of the tower. Comparison of the results from the theoretical study and field tests show promising agreement. 2 refs, 8 figs

  17. CONSTRAINING HIGH-SPEED WINDS IN EXOPLANET ATMOSPHERES THROUGH OBSERVATIONS OF ANOMALOUS DOPPLER SHIFTS DURING TRANSIT

    Energy Technology Data Exchange (ETDEWEB)

    Miller-Ricci Kempton, Eliza [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Rauscher, Emily, E-mail: ekempton@ucolick.org [Lunar and Planetary Laboratory, University of Arizona, 1629 East University Boulevard, Tucson, AZ 85721 (United States)

    2012-06-01

    Three-dimensional (3D) dynamical models of hot Jupiter atmospheres predict very strong wind speeds. For tidally locked hot Jupiters, winds at high altitude in the planet's atmosphere advect heat from the day side to the cooler night side of the planet. Net wind speeds on the order of 1-10 km s{sup -1} directed towards the night side of the planet are predicted at mbar pressures, which is the approximate pressure level probed by transmission spectroscopy. These winds should result in an observed blueshift of spectral lines in transmission on the order of the wind speed. Indeed, Snellen et al. recently observed a 2 {+-} 1 km s{sup -1} blueshift of CO transmission features for HD 209458b, which has been interpreted as a detection of the day-to-night (substellar to anti-stellar) winds that have been predicted by 3D atmospheric dynamics modeling. Here, we present the results of a coupled 3D atmospheric dynamics and transmission spectrum model, which predicts the Doppler-shifted spectrum of a hot Jupiter during transit resulting from winds in the planet's atmosphere. We explore four different models for the hot Jupiter atmosphere using different prescriptions for atmospheric drag via interaction with planetary magnetic fields. We find that models with no magnetic drag produce net Doppler blueshifts in the transmission spectrum of {approx}2 km s{sup -1} and that lower Doppler shifts of {approx}1 km s{sup -1} are found for the higher drag cases, results consistent with-but not yet strongly constrained by-the Snellen et al. measurement. We additionally explore the possibility of recovering the average terminator wind speed as a function of altitude by measuring Doppler shifts of individual spectral lines and spatially resolving wind speeds across the leading and trailing terminators during ingress and egress.

  18. Performance comparison of control schemes for variable-speed wind turbines

    Science.gov (United States)

    Bottasso, C. L.; Croce, A.; Savini, B.

    2007-07-01

    We analyze the performance of different control schemes when applied to the regulation problem of a variable-speed representative wind turbine. In particular, we formulate and compare a wind-scheduled PID, a LQR controller and a novel adaptive non-linear model predictive controller, equipped with observers of the tower states and wind. The simulations include gusts and turbulent winds of varying intensity in nominal as well as off-design operating conditions. The experiments highlight the possible advantages of model-based non-linear control strategies.

  19. Performance comparison of control schemes for variable-speed wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Bottasso, C L; Croce, A; Savini, B [Dipartimento di Ingegneria Aerospaziale, Politecnico di Milano, Via La Masa 34 I-20156 Milan (Italy)

    2007-07-15

    We analyze the performance of different control schemes when applied to the regulation problem of a variable-speed representative wind turbine. In particular, we formulate and compare a wind-scheduled PID, a LQR controller and a novel adaptive non-linear model predictive controller, equipped with observers of the tower states and wind. The simulations include gusts and turbulent winds of varying intensity in nominal as well as off-design operating conditions. The experiments highlight the possible advantages of model-based non-linear control strategies.

  20. The effects of disjunct sampling and averaging time on maximum mean wind speeds

    DEFF Research Database (Denmark)

    Larsén, Xiaoli Guo; Mann, J.

    2006-01-01

    Conventionally, the 50-year wind is calculated on basis of the annual maxima of consecutive 10-min averages. Very often, however, the averages are saved with a temporal spacing of several hours. We call it disjunct sampling. It may also happen that the wind speeds are averaged over a longer time...... period before being saved. In either case, the extreme wind will be underestimated. This paper investigates the effects of the disjunct sampling interval and the averaging time on the attenuation of the extreme wind estimation by means of a simple theoretical approach as well as measurements...

  1. Advantages on monitoring wind turbine nacelle oscillation

    DEFF Research Database (Denmark)

    Skrimpas, Georgios Alexandros; Marhadi, Kun Saptohartyadi; Hilmisson, Reynir

    2015-01-01

    and vibrations on blades, tower and drive train components, which may jeopardize their working condition. The present paper deals with the comparison and analysis of vibration signals from wind turbines subjected to various failure modes and operating conditions, such as blade misalignment, pitch malfunction......, ice accretion, damaged blade tips and yaw system defects. Theoretical analysis of nacelle movement at down wind and lateral direction is presented along with field results from multi megawatt wind turbines. Additionally the paper discusses the employment of nacelle accelerometers for cross reference...... of drive train defects, where propagation of vibrations from a drive train component to the nacelle frame usually indicates a late stage failure. This cross correlation is particularly beneficial towards accurate and consistent fault severity assessment....

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1998-05-01

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

  3. Maximum Output Power Control System of Variable-Speed Small Wind Generators

    Science.gov (United States)

    Amano, Yoko; Kajiwara, Hiroyuki

    This paper proposes a maximum output power control system of variable-speed small wind generators. Paying attention to an optimum rotational speed of a single phase AC wind generator which can obtain maximum output power according to natural wind speed, the proposed method adjusts the rotational speed of the single phase AC generator to the optimum rotational speed. Since this adjustment is realized on line so that it can be adapted for variable-speed wind, a generated power brake links directly with the single phase AC generator, and the rotational speed of the single phase AC generator is adjusted by controlling the current that flows the FET (Field-Effect Transistor) device as the generated power brake. In order to reduce heat loss of the FET device, the PWM (Pulse Width Modulation) controller is introduced. Moreover, the experimental system of the proposed method is constituted and the experiment is performed. Finally, the validity and the practicality of the proposed method are confirmed by experimental results.

  4. Frequency swept fibre laser for wind speed measurements

    DEFF Research Database (Denmark)

    Pedersen, Anders Tegtmeier

    This PhD thesis builds around a light source forming the basis for a novel type of wind measuring lidar. The lidar emits a train of laser pulses with each pulse being separated from its neighbours in frequency, while being closely spaced in time, thus combining the advantages of conventional cont...

  5. LQG Controller Design for Pitch Regulated Variable Speed Wind Turbine

    DEFF Research Database (Denmark)

    Imran, Raja Muhammed; Hussain, Dil Muhammad Akbar; Chen, Zhe

    2014-01-01

    the effect of disturbance acting on its rotor blades by wind. CART2 (Control Advanced Research Turbine) linear model is produced/generated by FAST (Fatigue, Aerodynamics, Structures and Turbulence) code to test its simulation on MATLAB/Simulink and various results are compared. The designed controller...

  6. Power curve report - with rotor equivalent wind speed

    DEFF Research Database (Denmark)

    Villanueva, Héctor; Gómez Arranz, Paula

    This report describes the power curve measurements carried out on a given wind turbine in a chosen period. The measurements were carried out following the measurement procedure in the draft of IEC 61400-12-1 Ed.2 [1], with some deviations mostly regarding uncertainty calculation. Here, the refere...

  7. Probability distribution of surface wind speed induced by convective adjustment on Venus

    Science.gov (United States)

    Yamamoto, Masaru

    2017-03-01

    The influence of convective adjustment on the spatial structure of Venusian surface wind and probability distribution of its wind speed is investigated using an idealized weather research and forecasting model. When the initially uniform wind is much weaker than the convective wind, patches of both prograde and retrograde winds with scales of a few kilometers are formed during active convective adjustment. After the active convective adjustment, because the small-scale convective cells and their related vertical momentum fluxes dissipate quickly, the large-scale (>4 km) prograde and retrograde wind patches remain on the surface and in the longitude-height cross-section. This suggests the coexistence of local prograde and retrograde flows, which may correspond to those observed by Pioneer Venus below 10 km altitude. The probability distributions of surface wind speed V during the convective adjustment have a similar form in different simulations, with a sharp peak around ∼0.1 m s-1 and a bulge developing on the flank of the probability distribution. This flank bulge is associated with the most active convection, which has a probability distribution with a peak at the wind speed 1.5-times greater than the Weibull fitting parameter c during the convective adjustment. The Weibull distribution P(> V) (= exp[-(V/c)k]) with best-estimate coefficients of Lorenz (2016) is reproduced during convective adjustments induced by a potential energy of ∼7 × 107 J m-2, which is calculated from the difference in total potential energy between initially unstable and neutral states. The maximum vertical convective heat flux magnitude is proportional to the potential energy of the convective adjustment in the experiments with the initial unstable-layer thickness altered. The present work suggests that convective adjustment is a promising process for producing the wind structure with occasionally generating surface winds of ∼1 m s-1 and retrograde wind patches.

  8. Extreme wind speed regime and weather patterns in the Barents Sea

    Science.gov (United States)

    Surkova, Galina; Krylov, Aleksey

    2016-04-01

    The synoptic patterns of extreme wind events over the Barents Sea during 1981-2010 are studied on the base of ERA-Interim reanalysis data (6-hours, 0.75x0.75 degrees of latitude and longitude). Frequency of events was defined after analysis of 50, 95, 99, 99.9 percentiles (V(0.50), V(0.95), V(0.99), V(0.999)) of wind speed probability distribution function over the central part of the sea where wind speed is the highest. First part of the study was devoted to the features of seasonal and interannual variability of the surface (10 m) wind speed. Results showed very slow and statistically almost insignificant decreasing of wind speed for all percentile speed values during 1981-2010. The highest standard deviation for annual percentile speed values were derived for the most seldom events, V(0.999). Mean values for the central part of the Barents Sea are V(0.95)=14.3 m/s, V(0.99)=17.2 m/s, V(0.999)=20.3 m/s. At the next stage the calendar of extreme events with wind speed more the threshold value V(0.99) was extracted. Sea level pressure (SLP) fields for these extreme events were classified by cluster analysis. Formal detection of typical SLP fields accompanying by storm winds allows to evaluate their frequency in different time periods. It is more reliable then use of wind speed data because the accuracy of SLP simulation in re-analysis and climate models is higher than that for the wind speed. The progress of the work is seen as further development of climate projection of extreme events on the base of CMIP5 scenarios through the projection of synoptic situations that create these events as it was shown in our previous works. Developed methodology allows to assess the frequency of synoptic events accompanying by hazards, not only in the past, but in the future. The study was supported by the Russian Science Foundation (project no. 14-37-00038).

  9. Highly reliable wind-rolling triboelectric nanogenerator operating in a wide wind speed range

    Science.gov (United States)

    Yong, Hyungseok; Chung, Jihoon; Choi, Dukhyun; Jung, Daewoong; Cho, Minhaeng; Lee, Sangmin

    2016-09-01

    Triboelectric nanogenerators are aspiring energy harvesting methods that generate electricity from the triboelectric effect and electrostatic induction. This study demonstrates the harvesting of wind energy by a wind-rolling triboelectric nanogenerator (WR-TENG). The WR-TENG generates electricity from wind as a lightweight dielectric sphere rotates along the vortex whistle substrate. Increasing the kinetic energy of a dielectric converted from the wind energy is a key factor in fabricating an efficient WR-TENG. Computation fluid dynamics (CFD) analysis is introduced to estimate the precise movements of wind flow and to create a vortex flow by adjusting the parameters of the vortex whistle shape to optimize the design parameters to increase the kinetic energy conversion rate. WR-TENG can be utilized as both a self-powered wind velocity sensor and a wind energy harvester. A single unit of WR-TENG produces open-circuit voltage of 11.2 V and closed-circuit current of 1.86 μA. Additionally, findings reveal that the electrical power is enhanced through multiple electrode patterns in a single device and by increasing the number of dielectric spheres inside WR-TENG. The wind-rolling TENG is a novel approach for a sustainable wind-driven TENG that is sensitive and reliable to wind flows to harvest wasted wind energy in the near future.

  10. Wind Turbine Gearbox Oil Filtration and Condition Monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Sheng, Shuangwen

    2015-10-25

    This is an invited presentation for a pre-conference workshop, titled advances and opportunities in lubrication: wind turbine, at the 2015 Society of Tribologists and Lubrication Engineers (STLE) Tribology Frontiers Conference held in Denver, CO. It gives a brief overview of wind turbine gearbox oil filtration and condition monitoring by highlighting typical industry practices and challenges. The presentation starts with an introduction by covering recent growth of global wind industry, reliability challenges, benefits of oil filtration and condition monitoring, and financial incentives to conduct wind operation and maintenance research, which includes gearbox oil filtration and condition monitoring work presented herein. Then, the presentation moves on to oil filtration by stressing the benefits of filtration, discussing typical main- and offline-loop practices, highlighting important factors considered when specifying a filtration system, and illustrating real-world application challenges through a cold-start example. In the next section on oil condition monitoring, a discussion on oil sample analysis, oil debris monitoring, oil cleanliness measurements and filter analysis is given based on testing results mostly obtained by and at NREL, and by pointing out a few challenges with oil sample analysis. The presentation concludes with a brief touch on future research and development (R and D) opportunities. It is hoping that the information presented can inform the STLE community to start or redirect their R and D work to help the wind industry advance.

  11. Flux-tube geometry and wind speed during an activity cycle

    CERN Document Server

    Pinto, R F; Rouillard, A P

    2016-01-01

    The solar wind speed at 1 AU shows variations in latitude and in time which reflect the evolution of the global background magnetic field during the activity cycle. It is commonly accepted that the terminal wind speed in a magnetic flux-tube is anti-correlated with its expansion ratio, which motivated the definition of widely-used semi-empirical scaling laws relating one to the other. In practice, such scaling laws require ad-hoc corrections. A predictive law based solely on physical principles is still missing. We test whether the flux-tube expansion is the controlling factor of the wind speed at all phases of the cycle and at all latitudes using a very large sample of wind-carrying open magnetic flux-tubes. We furthermore search for additional physical parameters based on the geometry of the coronal magnetic field which have an influence on the terminal wind flow speed. We use MHD simulations of the corona and wind coupled to a dynamo model to provide a large statistical ensemble of open flux-tubes which we...

  12. Near-surface wind speed statistical distribution: comparison between ECMWF System 4 and ERA-Interim

    Science.gov (United States)

    Marcos, Raül; Gonzalez-Reviriego, Nube; Torralba, Verónica; Cortesi, Nicola; Young, Doo; Doblas-Reyes, Francisco J.

    2017-04-01

    In the framework of seasonal forecast verification, knowing whether the characteristics of the climatological wind speed distribution, simulated by the forecasting systems, are similar to the observed ones is essential to guide the subsequent process of bias adjustment. To bring some light about this topic, this work assesses the properties of the statistical distributions of 10m wind speed from both ERA-Interim reanalysis and seasonal forecasts of ECMWF system 4. The 10m wind speed distribution has been characterized in terms of the four main moments of the probability distribution (mean, standard deviation, skewness and kurtosis) together with the coefficient of variation and goodness of fit Shapiro-Wilks test, allowing the identification of regions with higher wind variability and non-Gaussian behaviour at monthly time-scales. Also, the comparison of the predicted and observed 10m wind speed distributions has been measured considering both inter-annual and intra-seasonal variability. Such a comparison is important in both climate research and climate services communities because it provides useful climate information for decision-making processes and wind industry applications.

  13. A reward semi-Markov process with memory for wind speed modeling

    Science.gov (United States)

    Petroni, F.; D'Amico, G.; Prattico, F.

    2012-04-01

    The increasing interest in renewable energy leads scientific research to find a better way to recover most of the available energy. Particularly, the maximum energy recoverable from wind is equal to 59.3% of that available (Betz law) at a specific pitch angle and when the ratio between the wind speed in output and in input is equal to 1/3. The pitch angle is the angle formed between the airfoil of the blade of the wind turbine and the wind direction. Old turbine and a lot of that actually marketed, in fact, have always the same invariant geometry of the airfoil. This causes that wind turbines will work with an efficiency that is lower than 59.3%. New generation wind turbines, instead, have a system to variate the pitch angle by rotating the blades. This system able the wind turbines to recover, at different wind speed, always the maximum energy, working in Betz limit at different speed ratios. A powerful system control of the pitch angle allows the wind turbine to recover better the energy in transient regime. A good stochastic model for wind speed is then needed to help both the optimization of turbine design and to assist the system control to predict the value of the wind speed to positioning the blades quickly and correctly. The possibility to have synthetic data of wind speed is a powerful instrument to assist designer to verify the structures of the wind turbines or to estimate the energy recoverable from a specific site. To generate synthetic data, Markov chains of first or higher order are often used [1,2,3]. In particular in [1] is presented a comparison between a first-order Markov chain and a second-order Markov chain. A similar work, but only for the first-order Markov chain, is conduced by [2], presenting the probability transition matrix and comparing the energy spectral density and autocorrelation of real and synthetic wind speed data. A tentative to modeling and to join speed and direction of wind is presented in [3], by using two models, first

  14. Wind plant capacity credit variations: A comparison of results using multiyear actual and simulated wind-speed data

    Energy Technology Data Exchange (ETDEWEB)

    Milligan, M.R. [National Renewable Energy Lab., Golden, CO (United States)

    1997-12-31

    Although it is widely recognized that variations in annual wind energy capture can be significant, it is not clear how significant this effect is on accurately calculating the capacity credit of a wind plant. An important question is raised concerning whether one year of wind data is representative of long-term patterns. This paper calculates the range of capacity credit measures based on 13 years of actual wind-speed data. The results are compared to those obtained with synthetic data sets that are based on one year of data. Although the use of synthetic data sets is a considerable improvement over single-estimate techniques, this paper finds that the actual inter-annual variation in capacity credit is still understated by the synthetic data technique.

  15. Comparative study of speed estimators with highly noisy measurement signals for Wind Energy Generation Systems

    Energy Technology Data Exchange (ETDEWEB)

    Carranza, O. [Escuela Superior de Computo, Instituto Politecnico Nacional, Av. Juan de Dios Batiz S/N, Col. Lindavista, Del. Gustavo A. Madero 7738, D.F. (Mexico); Figueres, E.; Garcera, G. [Grupo de Sistemas Electronicos Industriales, Departamento de Ingenieria Electronica, Universidad Politecnica de Valencia, Camino de Vera S/N, 7F, 46020 Valencia (Spain); Gonzalez, L.G. [Departamento de Ingenieria Electronica, Universidad de los Andes, Merida (Venezuela)

    2011-03-15

    This paper presents a comparative study of several speed estimators to implement a sensorless speed control loop in Wind Energy Generation Systems driven by power factor correction three-phase boost rectifiers. This rectifier topology reduces the low frequency harmonics contents of the generator currents and, consequently, the generator power factor approaches unity whereas undesired vibrations of the mechanical system decrease. For implementation of the speed estimators, the compared techniques start from the measurement of electrical variables like currents and voltages, which contain low frequency harmonics of the fundamental frequency of the wind generator, as well as switching frequency components due to the boost rectifier. In this noisy environment it has been analyzed the performance of the following estimation techniques: Synchronous Reference Frame Phase Locked Loop, speed reconstruction by measuring the dc current and voltage of the rectifier and speed estimation by means of both an Extended Kalman Filter and a Linear Kalman Filter. (author)

  16. Comparison of Geophysical Model Functions for SAR Wind Speed Retrieval in Japanese Coastal Waters

    Directory of Open Access Journals (Sweden)

    Merete Badger

    2013-04-01

    Full Text Available This work discusses the accuracies of geophysical model functions (GMFs for retrieval of sea surface wind speed from satellite-borne Synthetic Aperture Radar (SAR images in Japanese coastal waters characterized by short fetches and variable atmospheric stability conditions. In situ observations from two validation sites, Hiratsuka and Shirahama, are used for comparison of the retrieved sea surface wind speeds using CMOD (C-band model4, CMOD_IFR2, CMOD5 and CMOD5.N. Of all the geophysical model functions (GMFs, the latest C-band GMF, CMOD5.N, has the smallest bias and root mean square error at both sites. All of the GMFs exhibit a negative bias in the retrieved wind speed. In order to understand the reason for this bias, all SAR-retrieved wind speeds are separated into two categories: onshore wind (blowing from sea to land and offshore wind (blowing from land to sea. Only offshore winds were found to exhibit the large negative bias, and short fetches from the coastline may be a possible reason for this. Moreover, it is clarified that in both the unstable and stable conditions, CMOD5.N has atmospheric stability effectiveness, and can keep the same accuracy with CMOD5 in the neutral condition. In short, at the moment, CMOD5.N is thought to be the most promising GMF for the SAR wind speed retrieval with the atmospheric stability correction in Japanese coastal waters, although there is ample room for future improvement for the effect from short fetch.

  17. Improving the atmospheric wind speed measured accuracy by the ground-based airglow imaging interferometer

    Science.gov (United States)

    Tang, Yuanhe; Yang, Rui; Gao, Haiyang; Zhai, Fengtao; Yu, Yang; Cui, Jin

    2017-02-01

    A prototype ground based airglow imaging interferometer (GBAII) has been constructed to observe the upper atmospheric wind velocity and temperature at an altitude of 90-100 km, but the GBAII's wind speed accuracy was found to be unsatisfactory with a value of 21.0 m/s. Three theoretical aspects have been investigated to improve the accuracy, with the following finding: 1) By replacing the surface coatings of the GBAII's 6 lenses and Michelson interferometer (MI) with a new wind-speed infrared film rather than the original visible light film, the accuracy can be increased by 3.0 m/s. 2) By replacing the original charge-coupled device (CCD) with a quantum efficiency (QE) of 0.38 at the wavelength of approximately 866 nm by an electron multiplying CCD (EMCCD) with QE of 0.95, the accuracy can be increased by 6.7 m/s. By adding all the factors that improve the accuracy of the GBAII, it can be improved by 15.0 m/s, which realizes the original aim of wind speed accuracy of 6.0 m/s. Experimental results have been obtained for two aspects: 1) By replacing the surface film on the GBAII's 6 lenses and MI interface, the wind speed accuracy has been increased by 3.8 m/s. 2) A new GBAII temperature controller has been constructed to control the environmental temperature in 0.2 K steps. The results obtained by the GBAII on Dec. 6, 2013 show an average atmospheric temperature of 206.5 K, zonal wind speed of -26.8 m/s and meridional wind speed of 28.1 m/s. These results are close to those of the TIMED (Thermosphere Ionosphere Mesosphere Energetics and Dynamics) satellite Doppler interferometer (TIDI) data collected at almost the same time.

  18. A prediction model for wind speed ratios at pedestrian level with simplified urban canopies

    Science.gov (United States)

    Ikegaya, N.; Ikeda, Y.; Hagishima, A.; Razak, A. A.; Tanimoto, J.

    2017-02-01

    The purpose of this study is to review and improve prediction models for wind speed ratios at pedestrian level with simplified urban canopies. We adopted an extensive database of velocity fields under various conditions for arrays consisting of cubes, slender or flattened rectangles, and rectangles with varying roughness heights. Conclusions are summarized as follows: first, a new geometric parameter is introduced as a function of the plan area index and the aspect ratio so as to express the increase in virtual density that causes wind speed reduction. Second, the estimated wind speed ratios in the range 0.05 database to within an error of ±25%. Lastly, the effects of the spatial distribution of the flow were investigated by classifying the regions near building models into areas in front of, to the side of, or behind the building. The correlation coefficients between the wind speeds averaged over the entire region, and the front or side region values are larger than 0.8. In contrast, in areas where the influence of roughness elements is significant, such as behind a building, the wind speeds are weakly correlated.

  19. Assessment of Gearbox Operational Loads and Reliability under High Mean Wind Speeds

    DEFF Research Database (Denmark)

    Dabrowski, Dariusz; Natarajan, Anand

    2015-01-01

    wind turbine that operates in storm conditions with mean wind speeds less than 30 m/s is presented. In the study, normal shut-downs of a wind turbine in storm conditions were investigated. The analysis were conducted for two storm control strategies and different wind conditions from an extreme...... of the model was based on the experimental data provided by NREL for 750 kW prototype gearbox. Failures of gearboxes caused by high dynamic loads have a significant influence on the cost of operation of wind farms. For these reasons in the study, the probability of failure of the gearbox working in an offshore...... operating gust, normal turbulence model and extreme turbulence model. In the paper, loads in the planetary gear are quantified as well as the torsional moments in the main shaft. On the basis of simulation results the annual probability of failure of the gearbox in a wind turbine with soft storm controller...

  20. A statistical study of underestimates of wind speeds by VHF radar

    Directory of Open Access Journals (Sweden)

    L. Thomas

    Full Text Available Comparisons are made between horizontal wind measurements carried out using a VHF-radar system at Aberystwyth (52.4°N, 4.1°W and radiosondes launched from Aberporth, some 50 km to the south-west. The radar wind results are derived from Doppler wind measurements at zenith angles of 6° in two orthogonal planes and in the vertical direction. Measurements on a total of 398 days over a 2-year period are considered, but the major part of the study involves a statistical analysis of data collected during 75 radiosonde flights selected to minimise the spatial separation of the two sets of measurements. Whereas good agreement is found between the two sets of wind direction, radar-derived wind speeds show underestimates of 4–6% compared with radiosonde values over the height range 4–14 km. Studies of the characteristics of this discrepancy in wind speeds have concentrated on its directional dependence, the effects of the spatial separation of the two sets of measurements, and the influence of any uncertainty in the radar measurements of vertical velocities. The aspect sensitivity of radar echoes has previously been suggested as a cause of underestimates of wind speeds by VHF radar. The present statistical treatment and case-studies show that an appropriate correction can be applied using estimates of the effective radar beam angle derived from a comparison of echo powers at zenith angles of 4.2° and 8.5°.

  1. A climatology of Brazilian surface wind speed trends using in-situ and climate reanalysis datasets from 1980-2014

    Science.gov (United States)

    Gilliland, J. M.; Keim, B. D.

    2015-12-01

    Wind speed trends have been extensively researched for the Northern Hemisphere and Australia. The general consensus among scientists is that wind speeds have declined over the past century. However, a minimal amount of research has focused on understanding how wind speeds changed across Brazil based on temporal and geographical perspectives. Therefore, this study provides a climatological assessment of wind speed trends across Brazil using in-situ and climatic model datasets from 1980-2014. Seasonal and annual trends are determined across the study area using linear and quantile regression. Geographical Information Systems is used to interpret and understand how wind speed trends have changed across Brazil. Preliminary results show two distinct wind speed trend patterns exist across Brazil. The largest wind speed magnitude increases occurred along northeastern and coastal Brazil, where as decreasing wind speeds have been observed for central and southeastern Brazil. Furthermore, quantile regression also shows the largest seasonal and annual wind trend fluctuations occur at lower (5%) and upper percentiles (95%) for both in-situ and climate model datasets. As a result, these findings indicate possible alterations in atmospheric and oceanic circulations could be affecting wind speed trends across Brazil and warrants further investigation and research.

  2. Recommended protocols for monitoring impacts of wind turbines on birds

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2007-04-15

    The behaviour of birds in relation to turbine locations are routinely monitored to determine risk factors. Baseline information is typically gathered on birds that reside or migrate through an area to be developed. The purpose of this document was to provide proponents of wind turbine projects with information on the types of protocols likely to be used for baseline studies and follow-up monitoring at proposed wind turbine sites in order to evaluate the impacts of wind turbines on birds. It is intended to facilitate the comparison of data among wind power projects. In order to meet federal environmental assessment requirements, proponents may also be required to follow-up on the actual impact of the installation on birds. This document described methods for collecting field data as well as pre-construction baseline sample methods that might be expected as part of the Environmental Impact Assessment process. Follow-up monitoring should be undertaken during the breeding season, non-breeding season, and at offshore locations. This document also discussed the need to monitor prospective wind turbine sites to determine whether any of the sites present an elevated risk for substantial bat mortality. An overview of post-construction follow-up studies was also provided for carcass searches and collision studies. Details on some of the sampling protocols that are likely to be appropriate for bird monitoring in the context of wind turbine environmental assessment were presented with reference to searches, standardized area searches, distance sampling, behavioural studies, point counts, microphone point counts, playback counts, stopover counts, passage migration counts, acoustic monitoring of migrating birds, radar monitoring, carcass searches, and estimating collisions using other methods. This document also included codes for breeding evidence and a sample data sheet for ten minute point counts. 3 appendices.

  3. Variability of the vertical profile of wind speed: characterization at various time scales and analytical approximation

    Science.gov (United States)

    Jourdier, Bénédicte; Plougonven, Riwal; Drobinski, Philippe; Dupont, Jean-Charles

    2014-05-01

    Wind measurements are key for the wind resource assessment. But as wind turbines get higher, wind measurement masts are often lower than the future wind turbine hub height. Therefore one of the first steps in the energy yield assessment is the vertical extrapolation of wind measurements. Such extrapolation is often done by approximating the vertical profile of wind speed with an analytical expression: either a logarithmic law which has a theoretical basis in Monin-Obukhov similarity theory; or a power law which is empirical. The present study analyzes the variability of the wind profile and how this variability affects the results of the vertical extrapolation methods. The study is conducted with data from the SIRTA observatory, 20km south of Paris (France). A large set of instrumentation is available, including sonic anemometers at 10 and 30 meters, a LIDAR measuring wind speeds from 40 to 200 meters and a SODAR measuring wind speeds starting from 100m up to 1km. The comparison between the instruments enables to characterize the measurements uncertainties. The observations show that close to the ground the wind is stronger during daytime and weaker at night while higher, around 150 m, the wind is weaker during daytime and stronger at night. Indeed the wind shear has a pronounced diurnal cycle. The vertical extrapolation methods currently used in the industry do not usually take into account the strong variability of the wind profile. The often fit the parameters of the extrapolation law, not on each time step, but on time-averaged profiles. The averaging period may be the whole measurement period or some part of it: there may be one constant parameter computed on the wind profile that was averaged on the whole year of measures, or the year of measures may be divided into a small number of cases (for example into night or daytime data, or into 4 seasons) and the parameter is adjusted for each case. The study analyzes thoroughly the errors generated by both

  4. First and second order semi-Markov chains for wind speed modeling

    Science.gov (United States)

    Prattico, F.; Petroni, F.; D'Amico, G.

    2012-04-01

    The increasing interest in renewable energy leads scientific research to find a better way to recover most of the available energy. Particularly, the maximum energy recoverable from wind is equal to 59.3% of that available (Betz law) at a specific pitch angle and when the ratio between the wind speed in output and in input is equal to 1/3. The pitch angle is the angle formed between the airfoil of the blade of the wind turbine and the wind direction. Old turbine and a lot of that actually marketed, in fact, have always the same invariant geometry of the airfoil. This causes that wind turbines will work with an efficiency that is lower than 59.3%. New generation wind turbines, instead, have a system to variate the pitch angle by rotating the blades. This system able the wind turbines to recover, at different wind speed, always the maximum energy, working in Betz limit at different speed ratios. A powerful system control of the pitch angle allows the wind turbine to recover better the energy in transient regime. A good stochastic model for wind speed is then needed to help both the optimization of turbine design and to assist the system control to predict the value of the wind speed to positioning the blades quickly and correctly. The possibility to have synthetic data of wind speed is a powerful instrument to assist designer to verify the structures of the wind turbines or to estimate the energy recoverable from a specific site. To generate synthetic data, Markov chains of first or higher order are often used [1,2,3]. In particular in [3] is presented a comparison between a first-order Markov chain and a second-order Markov chain. A similar work, but only for the first-order Markov chain, is conduced by [2], presenting the probability transition matrix and comparing the energy spectral density and autocorrelation of real and synthetic wind speed data. A tentative to modeling and to join speed and direction of wind is presented in [1], by using two models, first

  5. On Structural Health Monitoring of Wind Turbine Blades

    DEFF Research Database (Denmark)

    Skov, Jonas falk; Ulriksen, Martin Dalgaard; Dickow, Kristoffer Ahrens

    2013-01-01

    The aim of the present paper is to provide a state-of-the-art outline of structural health monitoring (SHM) techniques, utilizing temperature, noise and vibration, for wind turbine blades, and subsequently perform a typology on the basis of the typical four damage identification levels in SHM....... Before presenting the state-of-the-art outline, descriptions of structural damages typically occurring in wind turbine blades are provided along with a brief description of the four damage identification levels....

  6. Speed Control of Induction Motor Fed from Wind Turbine via Particle Swarm Optimization Based PI Controller

    Directory of Open Access Journals (Sweden)

    A.S. Oshaba

    2013-05-01

    Full Text Available Three-phase Induction Motor (IM is widely used in the industry because of its rugged construction and absence of brushes. However, speed control of IM is required depending on the desired speed and application. This study proposes a design of a Proportional Integral (PI controller using Particle Swarm Optimization (PSO algorithm to control the speed of an IM supplied from wind turbine. The wind turbine acts as a prime mover to a connected DC generator. Pulse Width Modulation (PWM is used to obtain three phase AC voltage from the output of DC generator. The proposed design problem of speed controller is formulated as an optimization problem. PSO is employed to search for optimal controller parameters by minimizing the time domain objective function. The performance of the proposed technique has been evaluated with respect to the variation of load torque and speed wind turbine. Also the performance of the proposed controller has been evaluated with the performance of the PI controller tuned by Genetic Algorithm (GA in order to demonstrate the superior efficiency of the proposed PSO in tuning PI controller. Simulation results emphasis on the better performance of the optimized PI controller based on PSO in compare to optimized PI controller based on GA over a wide range of load torque and speed wind turbine.

  7. Dependence of the surf zone aerosol on wind direction and wind speed at a coastal site on the Baltic Sea

    Directory of Open Access Journals (Sweden)

    Tymon Zieliński

    2003-09-01

    Full Text Available Since 1992 lidar-based measurements have been carried out under various meteorological conditions and at various times of the year. The aerosol optical properties were determined in the marine boundary layer as a function of altitude using such factors as wind direction, duration and velocity and aerosol size distribution and concentration. It was confirmed that in all cases, the total aerosol concentration, size distribution and aerosol extinction increase with wind speed but decrease with altitude. In the range of wind velocities from 1 to 15 m s-1 the mean aerosol optical thickness of the atmosphere (VIS obtained from the lidar varied from 0.1 to 0.38 for offshore winds and from 0.01 to about 0.1 for onshore winds, while the Ångström parameter for VIS oscillated around 0.65 for onshore winds and around 1 for offshore winds. Both parameters depended strongly on the history of the air mass above the Baltic Sea. Such aerosol optical thicknesses are in agreement with those obtained by other researchers in the Baltic Sea area.

  8. Quantifying equivalent neutral wind speed variance due to temporal and spatial difference between SeaWinds and in situ data

    Science.gov (United States)

    May, J. C.; Bourassa, M. A.

    2010-12-01

    Satellite measured winds, such as those reported by the SeaWinds scatterometer onboard the QuikSCAT satellite, can be validated with in situ data. The in situ data used for comparison with SeaWinds should be collocated in both time and space; however, due to the sparseness of data and time sampling intervals of the in situ data, ideally collocated observations are rare. Therefore, in situ data within a certain time and space range to the satellite overpass are used. This approach results in a total variance from three primary sources: variance in SeaWinds, variance in the comparison data, and variance associated with the temporal and spatial difference. The purpose of this study is to determine the amount of variance due to the temporal and spatial difference between two observations, in particular the equivalent neutral wind speed reported by SeaWinds and in situ data. Initially, this natural variability is examined in an idealized scenario where only in situ data is considered: the one-minute observations collected through the Shipboard Automated Meteorological and Oceanographic System (SAMOS) initiative from 2005 through 2009. The satellite is assumed to pass over the ship on the hour every hour. Shifts in time are used to examine the error associated with a mismatch in time. Taylor’s hypothesis can be used to translate a temporal shift to a spatial shift. The results show that the variance associated with the temporal difference increases as the mismatch in time increases. The temporal variance can also be separated into wind speed groups, which shows that there is a larger amount of variance associated with higher wind speeds. Confirmation of the idealized case method and results is done by using collocated SeaWinds and SAMOS observations. The comparison uses the closest collocation in both time and space to the satellite overpass. The total variance associated with a time shift from 0 to 60 minutes is estimated as the root mean square sum of the temporal

  9. Observer Backstepping Control for Variable Speed Wind Turbine

    DEFF Research Database (Denmark)

    Galeazzi, Roberto; Gryning, Mikkel Peter Sidoroff; Blanke, Mogens

    2013-01-01

    . The nonlinear controller aims at regulating the generator torque such that an optimal tip-speed ratio can be obtained. Simply relying on the measured rotor angular velocity the proposed observer backstepping controller guarantees global asymptotic tracking of the desired trajectory while maintaining a globally...

  10. Wind tunnel experiments to prove a hydraulic passive rotor speed control concept for variable speed wind turbines (poster)

    NARCIS (Netherlands)

    Diepeveen, N.F.B.; Jarquin Laguna, A.

    2012-01-01

    As alternative to geared and direct drive solutions, fluid power drive trains are being developed by several institutions around the world. The common configuration is where the wind turbine rotor is coupled to a hydraulic pump. The pump is connected through a high pressure line to a hydraulic motor

  11. Variation in wind speed and surface shear stress from open floor to porous parallel windbreaks: A wind tunnel study

    Science.gov (United States)

    Guan, De-Xin; Zhong, Ye; Jin, Chang-Jie; Wang, An-Zhi; Wu, Jia-Bing; Shi, Ting-Ting; Zhu, Ting-Yao

    2009-08-01

    As vegetative windbreaks become established on a large scale in agricultural ecosystems, understanding the influence of windbreak networks on the momentum budget of the atmospheric boundary layer becomes important. The authors conducted a wind tunnel experiment to study the variation of wind speed profile and surface shear stress of wind flow passing from an open surface to another with parallel windbreaks. Five spacing (L = 5, 10, 15, 20, 30 h, wherein h is the windbreak height) windbreak arrays with moderate porosity (aerodynamic porosity α = 0.501) were used in the experiments. Both near-floor and over-array wind speed measurements showed that airflow will approach equilibrium state behind a special windbreak of the array, varying from 4th to 9th windbreak when the spacing change from 30 to 5 h. Within the range of L/h values investigated, arrays with narrower spacing cause higher friction velocity and roughness length, which were up to 2.26 and nearly 100 times those observed over open floor, respectively. A semiempirical momentum budget model is developed on the arrayed surface to estimate windbreak drag and shear stress on the protected floor. Windbreak drag accounts for more than 80% of shear stress on the arrayed surface, and the shear stress on protected floor is less than 20% when L/h < 40 based on the model estimation. The sum of the two estimated components agrees well with the estimates obtained from over-array wind profiles.

  12. Wind Speed Forecasting Based on FEEMD and LSSVM Optimized by the Bat Algorithm

    Directory of Open Access Journals (Sweden)

    Wei Sun

    2015-06-01

    Full Text Available Affected by various environmental factors, wind speed presents high fluctuation, nonlinear and non-stationary characteristics. To evaluate wind energy properly and efficiently, this paper proposes a modified fast ensemble empirical model decomposition (FEEMD-bat algorithm (BA-least support vector machines (LSSVM (FEEMD-BA-LSSVM model combined with input selected by deep quantitative analysis. The original wind speed series are first decomposed into a limited number of intrinsic mode functions (IMFs with one residual series. Then a LSSVM is built to forecast these sub-series. In order to select input from environment variables, Cointegration and Granger causality tests are proposed to check the influence of temperature with different leading lengths. Partial correlation is applied to analyze the inner relationships between the historical speeds thus to select the LSSVM input. The parameters in LSSVM are fine-tuned by BA to ensure the generalization of LSSVM. The forecasting results suggest the hybrid approach outperforms the compared models.

  13. Mesoscale Near-Surface Wind Speed Variability Mapping with Synthetic Aperture Radar.

    Science.gov (United States)

    Young, George; Sikora, Todd; Winstead, Nathaniel

    2008-11-05

    Operationally-significant wind speed variability is often observed within synthetic aperture radar-derived wind speed (SDWS) images of the sea surface. This paper is meant as a first step towards automated distinguishing of meteorological phenomena responsible for such variability. In doing so, the research presented in this paper tests feature extraction and pixel aggregation techniques focused on mesoscale variability of SDWS. A sample of twenty eight SDWS images possessing varying degrees of near-surface wind speed variability were selected to serve as case studies. Gaussian high- and low-pass, local entropy, and local standard deviation filters performed well for the feature extraction portion of the research while principle component analysis of the filtered data performed well for the pixel aggregation. The findings suggest recommendations for future research.

  14. Decentralized & Adaptive Load-Frequency Control Scheme of Variable Speed Wind Turbines

    DEFF Research Database (Denmark)

    Hoseinzadeh, Bakhtyar; Silva, Filipe Miguel Faria da; Bak, Claus Leth

    2014-01-01

    In power systems with high penetration of Wind Power (WP), transferring a part of Load Frequency Control (LFC) burden to variable speed Wind Turbines (WTs) is inevitable. The conventional LFC schemes merely rely on frequency information and since frequency is a common variable throughout the netw......In power systems with high penetration of Wind Power (WP), transferring a part of Load Frequency Control (LFC) burden to variable speed Wind Turbines (WTs) is inevitable. The conventional LFC schemes merely rely on frequency information and since frequency is a common variable throughout...... the network, the contribution share of faraway and close WTs in the LFC plan is same, whereas there may be sufficient spinning reserve available in the local WTs close to the event location. This paper employs the initial voltage drop at the moment of perturbation to assess the proximity to the failure point...

  15. On capture and acceleration of heavy ions (a-particle) in high-speed solar wind

    Institute of Scientific and Technical Information of China (English)

    SONG; Liting(宋礼庭); XIAO; Chijie(肖池阶)

    2002-01-01

    The α-particles and other heavy ions, as well es a few protons are observed to be faster than the main part of protons by about the local Alfven speed in the high-speed solar wind. It is suggested that when the velocity of the solar wind is equal to the local Alfven velocity, another Iow-frequency kinetic Alfvan wave will be excitated, and trap ail the α-particles and a few protons, so these ions have a local Alfven velocity faster than the other parts of the solar wind. The undamping kinetic Alfven waves change into Iow-frequency Alfven solitons in the solar wind. This model can explain the observation and give the conditions of wave excitated and ions trapped.

  16. An adaptive control for a variable speed wind turbine using RBF neural network

    Directory of Open Access Journals (Sweden)

    El Mjabber E.

    2016-01-01

    Full Text Available In this work, a controller based on Radial Basis Functions (RBF for network adaptation is considered. The adaptive Neural Network (NN control approximates the nonlinear dynamics of the wind turbine based on input/output measurement and ensures smooth tracking of optimal tip speed-ratio at different wind speeds. The wind turbine system and this controller were modeled and a program to integrate the obtained coupled equations was developed under Matlab/Simulink software package. Then, performance of the controller was studied numerically. The proposed controller was found to effectively improve the control performance against large uncertainty of the wind turbine system. comparison with nonlinear dynamic State feedback control with Kalman filter controller was performed, and the obtained results have demonstrated the relevance of this RBFNN based controller.

  17. Short-term Probabilistic Forecasting of Wind Speed Using Stochastic Differential Equations

    DEFF Research Database (Denmark)

    Iversen, Jan Emil Banning; Morales González, Juan Miguel; Møller, Jan Kloppenborg;

    2016-01-01

    It is widely accepted today that probabilistic forecasts of wind power production constitute valuable information for both wind power producers and power system operators to economically exploit this form of renewable energy, while mitigating the potential adverse effects related to its variable...... and uncertain nature. In this paper, we propose a modeling framework for wind speed that is based on stochastic differential equations. We show that stochastic differential equations allow us to naturally capture the time dependence structure of wind speed prediction errors (from 1 up to 24 hours ahead) and......, most importantly, to derive point and quantile forecasts, predictive distributions, and time-path trajectories (also referred to as scenarios or ensemble forecasts), all by one single stochastic differential equation model characterized by a few parameters....

  18. Dual stator winding variable speed asynchronous generator: magnetic equivalent circuit with saturation, FEM analysis and experiments

    Science.gov (United States)

    Tutelea, L. N.; Muntean, N.; Deaconu, S. I.; Cunţan, C. D.

    2016-02-01

    The authors carried out a theoretical and experimental study of dual stator winding squirrel cage asynchronous generator (DSWA) behaviour in the presence of saturation regime (non-sinusoidal) due to the variable speed operation. The main aims are the determination of the relations of calculating the equivalent parameters of the machine windings, FEM validation of parameters and characteristics with free FEMM 4.2 computing software and the practice experimental tests for verifying them. Issue is limited to three phase range of double stator winding cage-asynchronous generator of small sized powers, the most currently used in the small adjustable speed wind or hydro power plants. The tests were carried out using three-phase asynchronous generator having rated power of 6 [kVA].

  19. Polar summer mesospheric extreme horizontal drift speeds during interplanetary corotating interaction regions (CIRs) and high-speed solar wind streams: Coupling between the solar wind and the mesosphere

    Science.gov (United States)

    Lee, Young-Sook; Kirkwood, Sheila; Kwak, Young-Sil; Kim, Kyung-Chan; Shepherd, Gordon G.

    2014-05-01

    We report the observation of echo extreme horizontal drift speed (EEHS, ≥ 300 m s-1) during polar mesospheric (80-90 km) summer echoes (PMSEs) by the VHF (52 MHz) radar at Esrange, Sweden, in years of 2006 and 2008. The EEHS occur in PMSEs as correlated with high-speed solar wind streams (HSSs), observed at least once in 12-17% of all hours of observation for the two summers. The EEHS rate peaks occur either during high solar wind speed in the early part of the PMSE season or during the arrival of interplanetary corotating interaction regions (CIRs) followed by peaks in PMSE occurrence rate after 1-4 days, in the latter part of the 2006 summer. The cause of EEHS rate peaks is likely under the competition between the interval of the CIR and HSS passage over the magnetosphere. A candidate process in producing EEHS is suggested to be localized strong electric field, which is caused by solar wind energy transfer from the interaction of CIR and HSS with the magnetosphere in a sequential manner. We suggest that EEHS are created by strong electric field, estimated as > 10-30 V m-1 at 85 km altitude, exceeding the mesospheric breakdown threshold field.

  20. Vibration-based angular speed estimation for multi-stage wind turbine gearboxes

    Science.gov (United States)

    Peeters, Cédric; Leclère, Quentin; Antoni, Jérôme; Guillaume, Patrick; Helsen, Jan

    2017-05-01

    Most processing tools based on frequency analysis of vibration signals are only applicable for stationary speed regimes. Speed variation causes the spectral content to smear, which encumbers most conventional fault detection techniques. To solve the problem of non-stationary speed conditions, the instantaneous angular speed (IAS) is estimated. Wind turbine gearboxes however are typically multi-stage gearboxes, consisting of multiple shafts, rotating at different speeds. Fitting a sensor (e.g. a tachometer) to every single stage is not always feasible. As such there is a need to estimate the IAS of every single shaft based on the vibration signals measured by the accelerometers. This paper investigates the performance of the multi-order probabilistic approach for IAS estimation on experimental case studies of wind turbines. This method takes into account the meshing orders of the gears present in the system and has the advantage that a priori it is not necessary to associate harmonics with a certain periodic mechanical event, which increases the robustness of the method. It is found that the MOPA has the potential to easily outperform standard band-pass filtering techniques for speed estimation. More knowledge of the gearbox kinematics is beneficial for the MOPA performance, but even with very little knowledge about the meshing orders, the MOPA still performs sufficiently well to compete with the standard speed estimation techniques. This observation is proven on two different data sets, both originating from vibration measurements on the gearbox housing of a wind turbine.

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

    Science.gov (United States)

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

    2003-04-01

    Early wind turbines used for performing mechanical work (pumping, grinding and cutting) optimized aerodynamics by being allowed to run at variable speed. Some of the earliest DC electric wind turbines were allowed to run at variable speed. With the advent of grid-connected AC turbines, rotational speeds were limited in order to control the wind turbine AC frequency output to equal the grid frequency. With the advent of semiconductor devices, attempts began as early as the 1970s to allow variable-speed operation of large-scale turbines. The introduction of a new generation of high-voltage, high-speed power electronic components allows a wide range of variable-speed operation for very-large-scale machines. Over the past 30 years a number of designs have been tested, a few of which have entered commercial operation. A number of these designs and their histories are described. A detailed description of a wide range of electrical methods for allowing variable-speed operation is provided.

  2. Fast tracking of wind speed with a differential absorption LiDAR system: first results of an experimental campaign at Stromboli volcano

    Science.gov (United States)

    Parracino, Stefano; Santoro, Simone; Maio, Giovanni; Nuvoli, Marcello; Aiuppa, Alessandro; Fiorani, Luca

    2017-04-01

    Carbon dioxide (CO2) is considered a precursor gas of volcanic eruptions by volcanologists. Monitoring the anomalous release of this parameter, we can retrieve useful information for the mitigation of volcanic hazards, such as for air traffic security. From a dataset collected during the Stromboli volcano field campaign, an assessment of the wind speed, in both horizontal and vertical paths, performing a fast tracking of this parameter was retrieved. This was determined with a newly designed shot-per-shot differential absorption LiDAR system operated in the near-infrared spectral region due to the simultaneous reconstruction of CO2 concentrations and wind speeds, using the same sample of LiDAR returns. A correlation method was used for the wind speed retrieval in which the transport of the spatial inhomogeneities of the aerosol backscattering coefficient, along the optical path of the system, was analyzed.

  3. A storm severity index based on return levels of wind speeds

    Science.gov (United States)

    Becker, Nico; Nissen, Katrin M.; Ulbrich, Uwe

    2015-04-01

    European windstorms related to extra-tropical cyclones cause considerable damages to infrastructure during the winter season. Leckebusch et al. (2008) introduced a storm severity index (SSI) based on the exceedances of the local 98th percentile of wind speeds. The SSI is based on the assumption that (insured) damage usually occurs within the upper 2%-quantile of the local wind speed distribution (i.e. if the 98th percentile is exceeded). However, critical infrastructure, for example related to the power network or the transportation system, is usually designed to withstand wind speeds reaching the local 50-year return level, which is much higher than the 98th percentile. The aim of this work is to use the 50-year return level to develop a modified SSI, which takes into account only extreme wind speeds relevant to critical infrastructure. As a first step we use the block maxima approach to estimate the spatial distribution of return levels by fitting the generalized extreme value (GEV) distribution to the wind speeds retrieved from different reanalysis products. We show that the spatial distributions of the 50-year return levels derived from different reanalyses agree well within large parts of Europe. The differences between the reanalyses are largely within the range of the uncertainty intervals of the estimated return levels. As a second step the exceedances of the 50-year return level are evaluated and compared to the exceedances of the 98th percentiles for different extreme European windstorms. The areas where the wind speeds exceed the 50-year return level in the reanalysis data do largely agree with the areas where the largest damages were reported, e.g. France in the case of "Lothar" and "Martin" and Central Europe in the case of "Kyrill". Leckebusch, G. C., Renggli, D., & Ulbrich, U. (2008). Development and application of an objective storm severity measure for the Northeast Atlantic region. Meteorologische Zeitschrift, 17(5), 575-587.

  4. Modeling and Design Optimization of Variable-Speed Wind Turbine Systems

    Directory of Open Access Journals (Sweden)

    Ulas Eminoglu

    2014-01-01

    Full Text Available As a result of the increase in energy demand and government subsidies, the usage of wind turbine system (WTS has increased dramatically. Due to the higher energy production of a variable-speed WTS as compared to a fixed-speed WTS, the demand for this type of WTS has increased. In this study, a new method for the calculation of the power output of variable-speed WTSs is proposed. The proposed model is developed from the S-type curve used for population growth, and is only a function of the rated power and rated (nominal wind speed. It has the advantage of enabling the user to calculate power output without using the rotor power coefficient. Additionally, by using the developed model, a mathematical method to calculate the value of rated wind speed in terms of turbine capacity factor and the scale parameter of the Weibull distribution for a given wind site is also proposed. Design optimization studies are performed by using the particle swarm optimization (PSO and artificial bee colony (ABC algorithms, which are applied into this type of problem for the first time. Different sites such as Northern and Mediterranean sites of Europe have been studied. Analyses for various parameters are also presented in order to evaluate the effect of rated wind speed on the design parameters and produced energy cost. Results show that proposed models are reliable and very useful for modeling and optimization of WTSs design by taking into account the wind potential of the region. Results also show that the PSO algorithm has better performance than the ABC algorithm for this type of problem.

  5. Damage tolerance and structural monitoring for wind turbine blades

    DEFF Research Database (Denmark)

    McGugan, Malcolm; Pereira, Gilmar Ferreira; Sørensen, Bent F.

    2015-01-01

    The paper proposes a methodology for reliable design and maintenance of wind turbine rotor blades using a condition monitoring approach and a damage tolerance index coupling the material and structure. By improving the understanding of material properties that control damage propagation...... it will be possible to combine damage tolerant structural design, monitoring systems, inspection techniques and modelling to manage the life cycle of the structures. This will allow an efficient operation of the wind turbine in terms of load alleviation, limited maintenance and repair leading to a more effective...

  6. Final Technical Report Recovery Act: Online Nonintrusive Condition Monitoring and Fault Detection for Wind Turbines

    Energy Technology Data Exchange (ETDEWEB)

    Wei Qiao

    2012-05-29

    The penetration of wind power has increased greatly over the last decade in the United States and across the world. The U.S. wind power industry installed 1,118 MW of new capacity in the first quarter of 2011 alone and entered the second quarter with another 5,600 MW under construction. By 2030, wind energy is expected to provide 20% of the U.S. electricity needs. As the number of wind turbines continues to grow, the need for effective condition monitoring and fault detection (CMFD) systems becomes increasingly important [3]. Online CMFD is an effective means of not only improving the reliability, capacity factor, and lifetime, but it also reduces the downtime, energy loss, and operation and maintenance (O&M) of wind turbines. The goal of this project is to develop novel online nonintrusive CMFD technologies for wind turbines. The proposed technologies use only the current measurements that have been used by the control and protection system of a wind turbine generator (WTG); no additional sensors or data acquisition devices are needed. Current signals are reliable and easily accessible from the ground without intruding on the wind turbine generators (WTGs) that are situated on high towers and installed in remote areas. Therefore, current-based CMFD techniques have great economic benefits and the potential to be adopted by the wind energy industry. Specifically, the following objectives and results have been achieved in this project: (1) Analyzed the effects of faults in a WTG on the generator currents of the WTG operating at variable rotating speed conditions from the perspective of amplitude and frequency modulations of the current measurements; (2) Developed effective amplitude and frequency demodulation methods for appropriate signal conditioning of the current measurements to improve the accuracy and reliability of wind turbine CMFD; (3) Developed a 1P-invariant power spectrum density (PSD) method for effective signature extraction of wind turbine faults with

  7. Validation of satellite SAR offshore wind speed maps to in-situ data, microscale and mesoscale model results

    DEFF Research Database (Denmark)

    Hasager, C.B.; Astrup, Poul; Barthelmie, R.J.

    2002-01-01

    planning of offshore wind farms. The report describes the validation analysis in detail for three sites in Denmark, Italy and Egypt. The site in Norway is analyzed by the Nansen Environmental and Remote SensingCentre (NERSC). Wind speed maps and wind direction maps from Earth Observation data recorded...... band in which the SAR wind speed observations have a strong negative bias. The bathymetry of Horns Rev combined with tidal currents give rise to bias in the SAR wind speed maps near areas of shallow, complex bottom topography in some cases. Atotal of 16 cases were analyzed for Horns Rev. For Maddalena...

  8. Dynamic Protective Control Strategy for Distributed Generation System with Fixed-speed Wind Turbines

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    The characteristics of induction generator based fixed-speed wind turbines (FSWT) are investigated. The impacts of different execution time in protective operations are studied under different fauit duration and various wind velocity situations, e.g. , FSWT stabilities of load shedding in distribution systems. Based on this research, a dynamic protective control strategy for a distributed generation system (DGS) with FSWT is proposed. Finally, simulation results demonstrate the effectiveness of the strategy.

  9. A Rotating Speed Controller Design Method for Power Levelling by Means of Inertia Energy in Wind Power Systems

    DEFF Research Database (Denmark)

    Qin, Zian; Blaabjerg, Frede; Loh, Poh Chiang

    2015-01-01

    Power fluctuation caused by wind speed variations may be harmful for the stability of the power system as well as the reliability of the wind power converter, since it may induce thermal excursions in the solder joints of the power modules. Using the wind turbine rotor inertia energy for power...... leveling has been studied before, but no quantified analysis or generic design method have been found. In this paper, the transfer functions from the wind speed to electrical power, electromagnetic torque, and rotating speed are built based on which the rotating speed controller is designed...

  10. Wind speed modeled as a semi-Markov process with memory

    CERN Document Server

    D'Amico, Guglielmo; Prattico, Flavio

    2012-01-01

    The increasing interest in renewable energy, particularly in wind, has given rise to the necessity of accurate models for the generation of good synthetic wind speed data. Markov chains are often used with this purpose but better models are needed to reproduce the statistical properties of wind speed data. In a previous paper we showed that semi-Markov processes are more appropriate for this purpose but to reach an accurate reproduction of real data features high order model should be used. In this work we introduce an indexed semi-Markov process that is able to fit real data. We downloaded a database, freely available from the web, in which are included wind speed data taken from L.S.I. -Lastem station (Italy) and sampled every 10 minutes. We then generate synthetic time series for wind speed by means of Monte Carlo simulations. The time lagged autocorrelation is then used to compare statistical properties of the proposed model with those of real data and also with a synthetic time series generated though a ...

  11. An Intelligent Ensemble Neural Network Model for Wind Speed Prediction in Renewable Energy Systems.

    Science.gov (United States)

    Ranganayaki, V; Deepa, S N

    2016-01-01

    Various criteria are proposed to select the number of hidden neurons in artificial neural network (ANN) models and based on the criterion evolved an intelligent ensemble neural network model is proposed to predict wind speed in renewable energy applications. The intelligent ensemble neural model based wind speed forecasting is designed by averaging the forecasted values from multiple neural network models which includes multilayer perceptron (MLP), multilayer adaptive linear neuron (Madaline), back propagation neural network (BPN), and probabilistic neural network (PNN) so as to obtain better accuracy in wind speed prediction with minimum error. The random selection of hidden neurons numbers in artificial neural network results in overfitting or underfitting problem. This paper aims to avoid the occurrence of overfitting and underfitting problems. The selection of number of hidden neurons is done in this paper employing 102 criteria; these evolved criteria are verified by the computed various error values. The proposed criteria for fixing hidden neurons are validated employing the convergence theorem. The proposed intelligent ensemble neural model is applied for wind speed prediction application considering the real time wind data collected from the nearby locations. The obtained simulation results substantiate that the proposed ensemble model reduces the error value to minimum and enhances the accuracy. The computed results prove the effectiveness of the proposed ensemble neural network (ENN) model with respect to the considered error factors in comparison with that of the earlier models available in the literature.

  12. Frequency support capability of variable speed wind turbine based on electromagnetic coupler

    DEFF Research Database (Denmark)

    You, Rui; Barahona Garzón, Braulio; Chai, Jianyun;

    2015-01-01

    In the variable speed wind turbine based on electromagnetic coupler (WT-EMC), a synchronous generator is directly coupled with grid. So like conventional power plants WT-EMC is able to support grid frequency inherently. But due to the reduced inertia of synchronous generator, its frequency support...... capability has to be enhanced. In this paper, the frequency support capability of WT-EMC is studied at three typical wind conditions and with two control strategies-droop control and inertial control to enhance its frequency support capability. The synchronous generator speed, more stable than the grid...

  13. Investigation of wind speed cooling effect on PV panels in windy locations

    DEFF Research Database (Denmark)

    Gökmen, Nuri; Hu, Weihao; Hou, Peng

    2016-01-01

    by taking into account generally underestimated wind speed cooling effect. Firstly, optimum tilt angle variations have been investigated and secondly yearly energy comparisons are made for cases with and without considering wind speed. A more accurate mathematical model is given to estimate yearly energy...... gain especially in the planning stage. Particle swarm optimization (PSO) algorithm is used to find optimum tilt angles for several time intervals. Results are given in detail through a case study in a windy northern European city, Aalborg, Denmark. The presented methodology can also easily be applied...

  14. Control strategy for a variable-speed wind energy conversion system

    Science.gov (United States)

    Jacob, A.; Veillette, D.; Rajagopalan, V.

    1979-01-01

    A control concept for a variable-speed wind energy conversion system is proposed, for which a self-exited asynchronous cage generator is used along with a system of thyristor converters. The control loops are the following: (1) regulation of the entrainment speed as function of available mechanical energy by acting on the resistance couple of the asynchronous generator; (2) control of electric power delivered to the asynchronous machine, functioning as a motor, for start-up of the vertical axis wind converter; and (3) limitation of the slip value, and by consequence, of the induction currents in the presence of sudden variations of input parameters.

  15. Mapping of extreme wind speed for landscape modelling of the Bohemian Forest, Czech Republic

    Directory of Open Access Journals (Sweden)

    L. Pop

    2014-01-01

    Full Text Available Extreme wind events are among the most damaging weather-related hazards in the Czech Republic, forestry is heavily affected. In order to successfully run a landscape model dealing with such effects, spatial distribution of extreme wind speed statistics is needed. The presented method suggests using sector-wise wind field calculations together with extreme value statistics fitted at a reference station. A special algorithm is proposed to provide the data in the form expected by the landscape model, i.e. raster data of annual wind speed maxima. The method is demonstrated on the area of Bohemian Forest that represents one of largest and most compact forested mountains in Central Europe. The reference meteorological station Churáňov is located within the selected domain. Numerical calculations were based on linear model of WAsP Engineering methodology. Observations were cleaned of inhomogeneity and classified into convective and non-convective cases using index CAPE. Due to disjunct sampling of synoptic data, appropriate corrections were applied to the observed extremes. Finally they were fitted with Gumbel distribution. The output of numerical simulation is presented for the windiest direction sector. Another map shows probability that annual extreme exceeds required threshold. The method offers a tool for generation of spatially variable annual maxima of wind speed. It assumes a small limited model domain containing a reliable wind measurement. We believe that this is typical setup for applications similar to one presented in the paper.

  16. Robust Active Disturbance Rejection Control Approach to Maximize Energy Capture in Variable-Speed Wind Turbines

    Directory of Open Access Journals (Sweden)

    Horacio Coral-Enriquez

    2013-01-01

    Full Text Available This paper proposes an alternative robust observer-based linear control technique to maximize energy capture in a 4.8 MW horizontal-axis variable-speed wind turbine. The proposed strategy uses a generalized proportional integral (GPI observer to reconstruct the aerodynamic torque in order to obtain a generator speed optimal trajectory. Then, a robust GPI observer-based controller supported by an active disturbance rejection (ADR approach allows asymptotic tracking of the generator speed optimal trajectory. The proposed methodology controls the power coefficient, via the generator angular speed, towards an optimum point at which power coefficient is maximum. Several simulations (including an actuator fault are performed on a 4.8 MW wind turbine benchmark model in order to validate the proposed control strategy and to compare it to a classical controller. Simulation and validation results show that the proposed control strategy is effective in terms of power capture and robustness.

  17. Can Weather Radars Help Monitoring and Forecasting Wind Power Fluctuations at Large Offshore Wind Farms?

    DEFF Research Database (Denmark)

    Trombe, Pierre-Julien; Pinson, Pierre; Madsen, Henrik

    2011-01-01

    The substantial impact of wind power fluctuations at large offshore wind farms calls for the development of dedicated monitoring and prediction approaches. Based on recent findings, a Local Area Weather Radar (LAWR) was installed at Horns Rev with the aim of improving predictability, controlability...... and potentially maintenance planning. Additional images are available from a Doppler radar covering the same area. The parallel analysis of rain events detection and of regime sequences in wind (and power) fluctuations demonstrates the interest of employing weather radars for a better operation and management...

  18. Wind tunnel wall interference effects on a supercritical airfoil at transonic speeds

    Science.gov (United States)

    Blackwell, J. A., Jr.; Pounds, G. A.

    1976-01-01

    Wind tunnel tests of a 10% supercritical airfoil have been conducted in the Lockheed Compressible Flow Facility at transonic speeds to determine the effects of varying wind tunnel wall porosity on airfoil performance. Wall configurations ranging in porosity from 1.3% to 10% were investigated at Reynolds numbers of 7 to 30 million. Experimental data presented to show the effect of varying wall porosity include airfoil surface pressures, airfoil forces, and wind tunnel wall pressures. Utilizing the experimental results, an assessment of the applicability of current subcritical theoretical methods to predict wall interference corrections in subsonic and transonic flows is made.

  19. Comparison of simulators for variable-speed wind turbine transient analysis

    DEFF Research Database (Denmark)

    Seman, S.; Iov, Florin; Niiranen, J.

    2006-01-01

    This paper presents a comparison of three variable-speed wind turbine simulators used for a 2 MW wind turbine short-term transient behaviour study during a symmetrical network disturbance. The simulator with doubly fed induction generator (DFIG) analytical model, the simulator with a finite element...... method (FEM) DFIG model and the wind turbine simulator with an analytical model of DFIG are compared. The comparison of the simulation results shows the influence of the different modelling approaches on the short-term transient simulation accuracy...

  20. Modeling and control of PMSG-based variable-speed wind turbine

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hong-Woo; Ko, Hee-Sang [Wind Energy Research Center, Korea Institute of Energy Research, Yuseong-gu Jang-Dong 71-2,305-343 Daejeon (Korea); Kim, Sung-Soo [Chungbuk National University (Korea)

    2010-01-15

    This paper presents a control scheme of a variable-speed wind turbine with a permanent-magnetic synchronous generator (PMSG) and full-scale back-to-back voltage source converter. A comprehensive dynamical model of the PMSG wind turbine and its control scheme is presented. The control scheme comprises both the wind-turbine control itself and the power-converter control. In addition, since the PMSG wind turbine is able to support actively the grid due to its capability to control independently active and reactive power production to the imposed set-values with taking into account its operating state and limits, this paper presents the supervisory reactive power control scheme in order to regulate/contribute the voltage at a remote location. The ability of the control scheme is assessed and discussed by means of simulations, based on a candidate site of the offshore wind farm in Jeju, Korea. (author)

  1. Transient and dynamic control of a variable speed wind turbine with synchronous generator

    Energy Technology Data Exchange (ETDEWEB)

    Jauch, Clemens [Riso National Laboratory, Wind Energy Department, PO Box 49, DK 4000 Roskilde, (Denmark)

    2007-02-14

    In this article, a controller for dynamic and transient control of a variable speed wind turbine with a full-scale converter-connected high-speed synchronous generator is presented. First, the phenomenon of drive train oscillations in wind turbines with full-scale converter-connected generators is discussed. Based on this discussion, a controller is presented that dampens these oscillations without impacting on the power that the wind turbine injects into the grid. Since wind turbines are increasingly demanded to take over power system stabilizing and control tasks, the presented wind turbine design is further enhanced to support the grid in transient grid events. A controller is designed that allows the wind turbine to ride through transient grid faults. Since such faults often cause power system oscillations, another controller is added that enables the turbine to participate in the damping of such oscillations. It is concluded that the controllers presented keep the wind turbine stable under any operating conditions, and that they are capable of adding substantial damping to the power system. (Author).

  2. Remotely sensed wind speed predicts soaring behaviour in a wide-ranging pelagic seabird.

    Science.gov (United States)

    Gibb, Rory; Shoji, Akiko; Fayet, Annette L; Perrins, Chris M; Guilford, Tim; Freeman, Robin

    2017-07-01

    Global wind patterns affect flight strategies in many birds, including pelagic seabirds, many of which use wind-powered soaring to reduce energy costs during at-sea foraging trips and migration. Such long-distance movement patterns are underpinned by local interactions between wind conditions and flight behaviour, but these fine-scale relationships are far less well understood. Here we show that remotely sensed ocean wind speed and direction are highly significant predictors of soaring behaviour in a migratory pelagic seabird, the Manx shearwater (Puffinus puffinus). We used high-frequency GPS tracking data (10 Hz) and statistical behaviour state classification to identify two energetic modes in at-sea flight, corresponding to flap-like and soar-like flight. We show that soaring is significantly more likely to occur in tailwinds and crosswinds above a wind speed threshold of around 8 m s(-1), suggesting that these conditions enable birds to reduce metabolic costs by preferentially soaring over flapping. Our results suggest a behavioural mechanism by which wind conditions may shape foraging and migration ecology in pelagic seabirds, and thus indicate that shifts in wind patterns driven by climate change could impact this and other species. They also emphasize the emerging potential of high-frequency GPS biologgers to provide detailed quantitative insights into fine-scale flight behaviour in free-living animals. © 2017 The Author(s).

  3. Weibull Wind-Speed Distribution Parameters Derived from a Combination of Wind-Lidar and Tall-Mast Measurements Over Land, Coastal and Marine Sites

    DEFF Research Database (Denmark)

    Gryning, Sven-Erik; Floors, Rogier Ralph; Peña, Alfredo

    2016-01-01

    Wind-speed observations from tall towers are used in combination with observations up to 600 m in altitude from a Doppler wind lidar to study the long-term conditions over suburban (Hamburg), rural coastal (Høvsøre) and marine (FINO3) sites. The variability in the wind field among the sites is ex...

  4. Estimation of Near Surface Wind Speeds in Strongly Rotating Flows

    CERN Document Server

    Crowell, Sean; Wicker, Louis

    2013-01-01

    Modeling studies consistently demonstrate that the most violent winds in tornadic vortices occur in the lowest tens of meters above the surface. These velocities are unobservable by radar platforms due to line of sight consider- ations. In this work, a methodology is developed which utilizes parametric tangential velocity models derived from Doppler radar measurements, to- gether with a tangential momentum and mass continuity constraint, to esti- mate the radial and vertical velocities in a steady axisymmetric frame. The main result is that information from observations aloft can be extrapolated into the surface layer of the vortex. The impact of the amount of information available to the retrieval is demonstrated through some numerical tests with pseudo-data.

  5. Characterization of the Flow Field and Wind Speed Profiles in Microbalance Wind Tunnels for Measurement of Agent Fate

    Science.gov (United States)

    2005-10-01

    wind speeds. Figure 4 shows the internal components of the Model Q600, including the 23mm diameter flow tube. Sample Cup Reference Cup Purge Gas...using a constant temperature hot-film anemometer (IFA-300 system; TSI, Minneapolis, MN). Special care was taken to extend the hotwire probe calibration...were performed from within approximately 0.254mm of the sample pan to near the top of the tube. The hot wire anemometer probes were mounted on a high

  6. A GIS wind resource map with tabular printout of monthly and annual wind speeds for 2,000 towns in Iowa

    Energy Technology Data Exchange (ETDEWEB)

    Brower, M.C. [Brower & Company, Andover, MA (United States); Factor, T. [Iowa Wind Energy Institute, Fairfield, IA (United States)

    1997-12-31

    The Iowa Wind Energy Institute, under a grant from the Iowa Energy Center, undertook in 1994 to map wind resources in Iowa. Fifty-meter met towers were erected at 13 locations across the state deemed promising for utility-scale wind farm development. Two years of summarized wind speed, direction, and temperature data were used to create wind resource maps incorporating effects of elevation, relative exposure, terrain roughness, and ground cover. Maps were produced predicting long-term mean monthly and annual wind speeds on a one-kilometer grid. The estimated absolute standard error in the predicted annual average wind speeds at unobstructed locations is 9 percent. The relative standard error between points on the annual map is estimated to be 3 percent. These maps and tabular data for 2,000 cities and towns in Iowa are now available on the Iowa Energy Center`s web site (http.//www.energy.iastate.edu).

  7. Recommended protocols for monitoring impacts of wind turbines on birds

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-07-28

    The proponent of a wind-powered generating station may be required to gather baseline information on birds that reside or migrate through the area to be developed. Proponents may also be required follow-up on the actual impact of the installation on the birds in order to fulfil the requirements of a federal environmental assessment. In order to evaluate impacts of wind turbines on birds, information was provided to proponents on the types of protocols likely to be useful for baseline studies and follow-up monitoring at proposed wind turbine sites. Uses of the document, field data collection, and reporting requirements were first discussed, followed by a detailed discussion of pre-construction baseline sample methods that might be expected as part of the Environmental Impact Assessment process. This information was presented according to monitoring during breeding season, non-breeding season, and offshore locations. Monitoring prospective wind turbine sites to determine whether any of the sites present an elevated risk for substantial bat mortality was also discussed. An overview of post-construction follow-up studies was provided for breeding season, non-breeding season, carcass searches and collision studies. The first appendix provided further details on some of the sampling protocols that are likely to be appropriate for bird monitoring in the context of wind turbine environmental assessment. These include area searches, standardized area searches, distance sampling, behavioural studies, point counts, microphone point counts, playback counts, stopover counts, passage migration counts, acoustic monitoring of migrating birds, radar monitoring, carcass searches, and estimating collisions using other methods. Codes for breeding evidence and a sample data sheet for ten minute point counts were also provides in appendices. 3 appendices.

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

    Energy Technology Data Exchange (ETDEWEB)

    Sheng, S.

    2011-08-01

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

  9. Statistical Short-Range Guidance for Peak Wind Speed Forecasts at Edwards Air Force Base, CA

    Science.gov (United States)

    Dreher, Joseph; Crawford, Winifred; Lafosse, Richard; Hoeth, Brian; Burns, Kerry

    2008-01-01

    The peak winds near the surface are an important forecast element for Space Shuttle landings. As defined in the Shuttle Flight Rules (FRs), there are peak wind thresholds that cannot be exceeded in order to ensure the safety of the shuttle during landing operations. The National Weather Service Spaceflight Meteorology Group (SMG) is responsible for weather forecasts for all shuttle landings. They indicate peak winds are a challenging parameter to forecast. To alleviate the difficulty in making such wind forecasts, the Applied Meteorology Unit (AMTJ) developed a personal computer based graphical user interface (GUI) for displaying peak wind climatology and probabilities of exceeding peak-wind thresholds for the Shuttle Landing Facility (SLF) at Kennedy Space Center. However, the shuttle must land at Edwards Air Force Base (EAFB) in southern California when weather conditions at Kennedy Space Center in Florida are not acceptable, so SMG forecasters requested that a similar tool be developed for EAFB. Marshall Space Flight Center (MSFC) personnel archived and performed quality control of 2-minute average and 10-minute peak wind speeds at each tower adjacent to the main runway at EAFB from 1997- 2004. They calculated wind climatologies and probabilities of average peak wind occurrence based on the average speed. The climatologies were calculated for each tower and month, and were stratified by hour, direction, and direction/hour. For the probabilities of peak wind occurrence, MSFC calculated empirical and modeled probabilities of meeting or exceeding specific 10-minute peak wind speeds using probability density functions. The AMU obtained and reformatted the data into Microsoft Excel PivotTables, which allows users to display different values with point-click-drag techniques. The GUT was then created from the PivotTables using Visual Basic for Applications code. The GUI is run through a macro within Microsoft Excel and allows forecasters to quickly display and

  10. Bernoulli-Langevin Wind Speed Model for Simulation of Storm Events

    Science.gov (United States)

    Fürstenau, Norbert; Mittendorf, Monika

    2016-12-01

    We present a simple nonlinear dynamics Langevin model for predicting the instationary wind speed profile during storm events typically accompanying extreme low-pressure situations. It is based on a second-degree Bernoulli equation with δ-correlated Gaussian noise and may complement stationary stochastic wind models. Transition between increasing and decreasing wind speed and (quasi) stationary normal wind and storm states are induced by the sign change of the controlling time-dependent rate parameter k(t). This approach corresponds to the simplified nonlinear laser dynamics for the incoherent to coherent transition of light emission that can be understood by a phase transition analogy within equilibrium thermodynamics [H. Haken, Synergetics, 3rd ed., Springer, Berlin, Heidelberg, New York 1983/2004.]. Evidence for the nonlinear dynamics two-state approach is generated by fitting of two historical wind speed profiles (low-pressure situations "Xaver" and "Christian", 2013) taken from Meteorological Terminal Air Report weather data, with a logistic approximation (i.e. constant rate coefficients k) to the solution of our dynamical model using a sum of sigmoid functions. The analytical solution of our dynamical two-state Bernoulli equation as obtained with a sinusoidal rate ansatz k(t) of period T (=storm duration) exhibits reasonable agreement with the logistic fit to the empirical data. Noise parameter estimates of speed fluctuations are derived from empirical fit residuals and by means of a stationary solution of the corresponding Fokker-Planck equation. Numerical simulations with the Bernoulli-Langevin equation demonstrate the potential for stochastic wind speed profile modeling and predictive filtering under extreme storm events that is suggested for applications in anticipative air traffic management.

  11. Validation of AROME wind speed forecasts against mast observations in the Finnish wind power resource mapping project

    Science.gov (United States)

    Kilpinen, J.

    2009-09-01

    The upgrade of the Finnish wind power resource mapping is going on. The previous mapping was published 1991 and it was mainly based on observations. The climatology for the present mapping is made with meso-scale NWP mode and down scaling to detailed topography using WAsP-model. One of the tasks in the mapping is to validate/verify the model wind speed against mast observation. There is a group of masts with measurement heights around 100 meters available for this purpose. Most of the masts are in the Helsinki Testbed area while some of the masts are at existing wind farms. From a larger data set (ERA INTERIM) a representative sample of months has been chosen and also two extra 12 month sets representing extreme wind conditions. The total sample consists of 72 separate months. The lateral boundaries and first guess is from ERA INTERIM data. HIRLAM model (with 7.5 km resolution) is used to make initial analyses for 2.5 km AROME model with 6 hourly data assimilation cycle. Finally AROME model is used to simulate the wind climate. The output is with 3 hour interval. The WAsP-model is used to downscale the wind in coastal areas and hills in Northern Finland with 250 meter resolution and corresponding roughness. For validation the operative AROME is used. Only 00 UTC initial analyses are used to make forecasts up to +24 hours with 3 hourly outputs to cover the diurnal cycle. The validation period began from June 2008 and it will last to the end of the project in October 2009. The number of masts is around 20 and the height of measurements is typically between 60 and 100 meters. The validation is made with traditional verification methods. A special attention is also made to the quality control of observations. A part of the wind speed measurement instruments are not typical cup anemometers but acoustic instruments (Vaisala VXT520). The detailed results of validation will be presented. The preliminary results for the year 2008 indicate that there is a slight positive

  12. Predicting extreme wind speeds on a tropical island for multi-peril catastrophe modelling

    Science.gov (United States)

    Thornton, James; Moncoulon, David; Millinship, Ian; Raven, Emma

    2013-04-01

    Catastrophe models are important tools used by the reinsurance industry for assessing and managing risk. Here, we present the methods used to develop high-resolution wind hazard maps for the Indian Ocean island of La Réunion. As the recent Cyclone Dumile (January 2013) reminded us, the island is at considerable risk from the extreme weather associated with tropical cyclones. It also contains a significant proportion of the total value insured in French overseas territories. The wind maps, alongside flood and storm surge maps, were ultimately combined with exposure information in a multi-peril catastrophe model to provide probabilistic estimates of insured loss. Our wind mapping methodology used established extreme value theory statistics to estimate the annual probability of extreme wind speeds, including those exceeding the observed maxima of our 19 year record, at meteorological stations. This gave approximate wind speeds for a range of return periods at these specific locations. Since the spatial density of the stations was insufficient to resolve the numerous potential effects of the complex island topography, geographically weighted regression (GWR) models were then developed to interpolate these cyclonic wind speeds across the entire island. Factors known to affect local wind speed such as elevation, surface roughness and coastal proximity were explicitly accounted for. Using this advanced interpolation method, wind hazard maps were produced for six return periods between 1 in 10 and 1 in 1000 years. Our maps compared favourably with those of historical events, and also showed patterns of wind speed in agreement with the findings of other studies investigating the effects of topography. Leave-one-out cross-validation (LOOCV) further confirmed the satisfactory performance of the models in providing a robust and comprehensive description of wind patterns during cyclone passage. Uncertainty increased with return period as more extrapolation of the limited

  13. Monitoring of offshore wind farm using reliable communication

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, K.G.; Gajranib, K.; Bhargavac, A. [Rajasthan Technical Univ.. Dept. of Electrical Engineering, Kota (India)

    2012-07-01

    Due to rapid exhaustion of fossil fuels, new renewable technologies for electricity generation are insisted upon to meet the continuous growing demand of energy all across the globe. Wind energy as a green energy is a favorable option, among other available renewable sources. The offshore wind farm capacity is growing rapidly, but it's uncertain and intermittent nature offers great challenges to power system engineers. The cost of repair and down time, results into extensive damage and reduced profitability. This necessitates the requirement of fast and reliable communication network for the monitoring and controlling of the wind farm. In this paper, we have proposed the communication network for medium offshore wind farm (160MW). The wind farm consists of four clusters; each cluster comprises of 10 Wind Turbines (WTs), each of capacity 4MW. A WT can be represented by nine logical nodes according to IEC-61400-25 standard. The functions of logical nodes are modeled in terms of analogue /status/control information. The wind farm has been modeled in OPNET modeler and the performance of the communication network is evaluated in terms of End to End delay and packet drop, using Synchronous Optical NETwork (SONET) standard. (Author)

  14. THE CHARACTERISTICS OF THE OPERATING PARAMETERS OF THE VERTICAL AXIS WIND TURBINE FOR THE SELECTED WIND SPEED

    Directory of Open Access Journals (Sweden)

    Zbigniew Czyż

    2017-03-01

    Full Text Available The article presents the results of examining a wind turbine on the vertical axis of rotation. The study was conducted in an open circuit wind tunnel Gunt HM 170 in the laboratory of the Department of Thermodynamics, Fluid Mechanics and Aviation Propulsion Systems in Lublin University of Technology. The subject of research was a rotor based on the patent PL 219985. The research object in the form of rotor consists of blades capable of altering the surface of the active area (receiving kinetic energy of the wind. The study was performed on appropriately scaled and geometrically similar models with maintaining, relevant to the type of research, the criterion numbers. Research objects in the form of rotors with different angles of divergence of blades were made using a 3D powder printer ZPrinter® 450. The results of the research conducted were carried out at the selected flow velocity of 6.5 m/s for three angles of divergence, ie. 30°, 60°, and 90° at variable rotational speed. The applied research station allows braking of the turbine to the required speed, recording velocity and torque, which allows to obtain characteristics of torque and power as a function of rotor speed.

  15. Validation of satellite SAR offshore wind speed maps to in-situ data, microscala and mesoscale model results

    Energy Technology Data Exchange (ETDEWEB)

    Hasager, C.B.; Astrup, P.; Barthelmie, R.; Dellwik, E.; Hoffmann Joergensen, B.; Gylling Mortensen, N.; Nielsen, M.; Pryor, S.; Rathmann, O.

    2002-05-01

    A validation study has been performed in order to investigate the precision and accuracy of the satellite-derived ERS-2 SAR wind products in offshore regions. The overall project goal is to develop a method for utilizing the satellite wind speed maps for offshore wind resources, e.g. in future planning of offshore wind farms. The report describes the validation analysis in detail for three sites in Denmark, Italy and Egypt. The site in Norway is analyzed by the Nansen Environmental and Remote Sensing Centre (NERSC). Wind speed maps and wind direction maps from Earth Observation data recorded by the ERS-2 SAR satellite have been obtained from the NERSC. For the Danish site the wind speed and wind direction maps have been compared to in-situ observations from a met-mast at Horns Rev in the North Sea located 14 km offshore. The SAR wind speeds have been area-averaged by simple and advanced footprint modelling, ie. the upwind conditions to the meteorological mast are explicitly averaged in the SAR wind speed maps before comparison. The comparison results are very promising with a standard error of {+-} 0.61 m s{sup -1}, a bias {approx}2 m s{sup -1} and R{sup 2} {approx}0.88 between in-situ wind speed observations and SAR footprint averaged values at 10 m level. Wind speeds predicted by the local scale model LINCOM and the mesoscale model KAMM2 have been compared to the spatial variations in the SAR wind speed maps. The finding is a good correspondence between SAR observations and model results. Near the coast is an 800 m wide band in which the SAR wind speed observations have a strong negative bias. The bathymetry of Horns Rev combined with tidal currents give rise to bias in the SAR wind speed maps near areas of shallow, complex bottom topography in some cases. A total of 16 cases were analyzed for Horns Rev. For Maddalena in Italy five cases were analyzed. At the Italian site the SAR wind speed maps were compared to WAsP and KAMM2 model results. The WAsP model

  16. Effect of tuned unified power flow controller to mitigate the rotor speed instability of fixed-speed wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Jayashri, R. [Department of Electrical and Electronics Engineering, Sri Venkateswara College of Engineering (Affiliated to Anna University), Pennalur, Sriperumbudur, Tamilnadu 602105 (India); Kumudini Devi, R.P. [Department of Electrical and Electronics Engineering, College of Engineering, Anna University, Chennai (India)

    2009-03-15

    In this paper, the dynamic performance of grid connected Wind Energy Conversion System (WECS) is analysed in terms of the newly defined concept of rotor speed stability. The WECS is considered as a fixed-speed system that is equipped with a squirrel-cage induction generator. The drive-train is represented as a two-mass model. Results show that for a particular fault simulated the voltage at the Point of Common Coupling (PCC) drops below 80% immediately after fault application and settles at a low value. The rotor speed of induction generators becomes unstable. In order to improve the low voltage ride-through of WECS under fault conditions and to damp the rotor speed oscillations of induction generator, an Unified Power Flow Controller (UPFC) is employed. The gains of this FACTS controller are tuned with a simple Genetic Algorithm (GA). It is observed that UPFC helps not only in regulating the voltage, but also in mitigating the rotor speed instability. (author)

  17. Two Machine Learning Approaches for Short-Term Wind Speed Time-Series Prediction.

    Science.gov (United States)

    Ak, Ronay; Fink, Olga; Zio, Enrico

    2016-08-01

    The increasing liberalization of European electricity markets, the growing proportion of intermittent renewable energy being fed into the energy grids, and also new challenges in the patterns of energy consumption (such as electric mobility) require flexible and intelligent power grids capable of providing efficient, reliable, economical, and sustainable energy production and distribution. From the supplier side, particularly, the integration of renewable energy sources (e.g., wind and solar) into the grid imposes an engineering and economic challenge because of the limited ability to control and dispatch these energy sources due to their intermittent characteristics. Time-series prediction of wind speed for wind power production is a particularly important and challenging task, wherein prediction intervals (PIs) are preferable results of the prediction, rather than point estimates, because they provide information on the confidence in the prediction. In this paper, two different machine learning approaches to assess PIs of time-series predictions are considered and compared: 1) multilayer perceptron neural networks trained with a multiobjective genetic algorithm and 2) extreme learning machines combined with the nearest neighbors approach. The proposed approaches are applied for short-term wind speed prediction from a real data set of hourly wind speed measurements for the region of Regina in Saskatchewan, Canada. Both approaches demonstrate good prediction precision and provide complementary advantages with respect to different evaluation criteria.

  18. Application of the Single Imputation Method to Estimate Missing Wind Speed Data in Malaysia

    Directory of Open Access Journals (Sweden)

    Nurulkamal Masseran

    2013-07-01

    Full Text Available In almost all research fields, the procedure for handling missing values must be addressed before a detailed analysis can be made. Thus, a suitable method of imputation should be chosen to address the missing value problem. Wind speed has been found in engineering practice to be the most significant parameter in wind power. However, researchers are sometimes faced with the problem of missing wind speed data caused by equipment failure. In this study, we attempt to implement four types of single imputation methods to estimate the wind speed data from three adjacent stations in Malaysia. The methods, known as the site-dependent effect method, the hour mean method, the last and next method, and the row mean method, are compared based on the index of agreement to identify the best method for estimating the missing values. The results indicate that the last and next is the best of the three methods for estimating the missing data for the wind stations considered.

  19. CYGNSS Observations of Surface Wind Speeds in Oceanic Tropical and Extratropical Cyclones

    Science.gov (United States)

    Posselt, D. J.; Crespo, J.; Naud, C. M.

    2016-12-01

    The Cyclone Global Navigation Satellite System (CYGNSS) mission is the first of the new generation of NASA Earth Venture missions, and consists of a constellation of eight small satellites scheduled for launch in November 2016. The mission utilizes GPS signals reflected from the Earth's surface to infer near-surface wind speeds over the global tropical oceans. The eight-satellite constellation will observe ocean-surface wind speeds in all weather conditions (including in heavy precipitation) with a median revisit time of approximately 3 hours. While CYGNSS is designed to measure wind speeds in the inner core of tropical cyclones, it will observe near-surface winds over all oceanic regions within the span of its orbit. The orbit inclination is 35 degrees, which means that the satellite will observe primarily the tropics and sub-tropics; however, because the antennae are angled 28 degrees off-nadir, the effective range of latitudes spans -40 to 40 degrees. As such, CYGNSS will observe regions known to be characterized by rapid extratropical cyclone development (e.g., the southern portion of the Gulf Stream off the U.S. East Coast). In this presentation, we discuss CYGNSS sampling characteristics, with an eye toward its potential to observe winds not only in tropical cyclones, but in extratropical cyclones as well. We simulate orbits over a historical extratropical storm, and also utilize a multi-year database of cyclone centers to determine CYGNSS sampling characteristics integrated over many storms.

  20. Validation of sea surface temperature, wind speed and integrated water vapour from MSMR measurements. Project report

    Digital Repository Service at National Institute of Oceanography (India)

    Muraleedharan, P.M.

    and autonomous weather station) were utilized for measuring sea truth parameters such as sea surface temperature (SST), Sea Surface Wind Speed (WS) and Columnar Water Vapor (WV). Total match-ups for SST and WS measured from various platforms exceeded 1400 (2 hrs...

  1. Improving Fault Ride-Through Capability of Variable Speed Wind Turbines in Distribution Networks

    DEFF Research Database (Denmark)

    Mokryani, Geev; Siano, P.; Piccolo, Antonio;

    2013-01-01

    In this paper, a fuzzy controller for improving the fault ride-through (FRT) capability of variable speed wind turbines (WTs) equipped with a doubly fed induction generator (DFIG) is presented. DFIGs can be used as reactive power sources to control the voltage at the point of common coupling (PCC...

  2. Conceptions of Tornado Wind Speed and Land Surface Interactions among Undergraduate Students in Nebraska

    Science.gov (United States)

    Van Den Broeke, Matthew S.; Arthurs, Leilani

    2015-01-01

    To ascertain novice conceptions of tornado wind speed and the influence of surface characteristics on tornado occurrence, 613 undergraduate students enrolled in introductory science courses at a large state university in Nebraska were surveyed. Our findings show that students lack understanding of the fundamental concepts that (1) tornadoes are…

  3. FUZZY LOGIC BASED INTELLIGENT CONTROL OF A VARIABLE SPEED CAGE MACHINE WIND GENERATION SYSTEM

    Science.gov (United States)

    The paper describes a variable-speed wind generation system where fuzzy logic principles are used to optimize efficiency and enhance performance control. A squirrel cage induction generator feeds the power to a double-sided pulse width modulated converter system which either pump...

  4. FUZZY LOGIC BASED INTELLIGENT CONTROL OF A VARIABLE SPEED CAGE MACHINE WIND GENERATION SYSTEM

    Science.gov (United States)

    The paper describes a variable-speed wind generation system where fuzzy logic principles are used to optimize efficiency and enhance performance control. A squirrel cage induction generator feeds the power to a double-sided pulse width modulated converter system which either pump...

  5. Observations of Downwind Development of Wind Speed and Variance Profiles at Bognaes and Comparison with Theory

    DEFF Research Database (Denmark)

    Jensen, Niels Otto; Højstrup, Jørgen; Peterson, E. W.

    1979-01-01

    Observations of atmospheric flow over a change in surface roughness are reported. Both wind speed and turbulence characteristics were measured. Although the observation site departed from the ideal assumed in roughness change models, it was found that the predictions of `second-order closure...

  6. Vibration measurement of a model wind turbine using high speed photogrammetry

    NARCIS (Netherlands)

    Kalpoe, D.; Khoshelham, K.; Gorte, B.

    2011-01-01

    We investigate the application of the photogrammetric approach to measuring the vibration of a model wind turbine in a sequence of stereo image pairs acquired by high speed cameras. The challenge of the photogrammetric measurement of a highly dynamic phenomenon is the efficiency of the point measure

  7. High-resolution daily gridded datasets of air temperature and wind speed for Europe

    Directory of Open Access Journals (Sweden)

    S. Brinckmann

    2015-08-01

    et al. (2011 is used. At first, predictor fields of altitude, continentality and zonal mean temperature are chosen for a regression applied to monthly station data. The residuals of the monthly regression and the deviations of the daily data from the monthly averages are interpolated using simple kriging in a second and third step. For wind speed a new method based on the concept used for temperature was developed, involving predictor fields of exposure, roughness length, coastal distance and ERA Interim reanalysis wind speed at 850 hPa. Interpolation uncertainty is estimated by means of the kriging variance and regression uncertainties. Furthermore, to assess the quality of the final daily grid data, cross validation is performed. Explained variance ranges from 70 to 90 % for monthly temperature and from 50 to 60 % for monthly wind speed. The resulting RMSE for the final daily grid data amounts to 1–2 °C and 1–1.5 m s−1 (depending on season and parameter for daily temperature parameters and daily mean wind speed, respectively. The datasets presented in this article are published at http://dx.doi.org/10.5676/DWD_CDC/DECREG0110v1.

  8. Verification of the ECMWF ensemble forecasts of wind speed against analyses and observations

    DEFF Research Database (Denmark)

    Pinson, Pierre; Hagedorn, Renate

    2012-01-01

    A framework for the verification of ensemble forecasts of near-surface wind speed is described. It is based on existing scores and diagnostic tools, though considering observations from synoptic stations as reference instead of the analysis. This approach is motivated by the idea of having a user...

  9. Comparison of Geophysical Model Functions for SAR Wind Speed Retrieval in Japanese Coastal Waters

    DEFF Research Database (Denmark)

    Takeyama, Yuko; Ohsawa, Teruo; Kozai, Katsutoshi

    2013-01-01

    from two validation sites, Hiratsuka and Shirahama, are used for comparison of the retrieved sea surface wind speeds using CMOD (C-band model)4, CMOD_IFR2, CMOD5 and CMOD5.N. Of all the geophysical model functions (GMFs), the latest C-band GMF, CMOD5.N, has the smallest bias and root mean square error...

  10. Hourly interaction between wind speed and energy fluxes in Brazilian Wetlands - Mato Grosso - Brazil

    Directory of Open Access Journals (Sweden)

    THIAGO R. RODRIGUES

    Full Text Available ABSTRACT Matter and energy flux dynamics of wetlands are important to understand environmental processes that govern biosphere-atmosphere interactions across ecosystems. This study presents analyses about hourly interaction between wind speed and energy fluxes in Brazilian Wetlands - Mato Grosso - Brazil. This study was conducted in Private Reserve of Natural Heritage (PRNH SESC, 16º39'50''S; 56º47'50''W in Brazilian Wetland. According to Curado et al. (2012, the wet season occurs between the months of January and April, while the June to September time period is the dry season. Results presented same patterns in energies fluxes in all period studied. Wind speed and air temperature presented same patterns, while LE was relative humidity presented inverse patterns of the air temperature. LE was predominant in all seasons and the sum of LE and H was above 90% of net radiation. Analyses of linear regression presented positive interactions between wind speed and LE, and wind speed and H in all seasons, except in dry season of 2010. Confidence coefficient regression analyses present statistical significance in all wet and dry seasons, except dry season of 2010, suggest that LE and H had interaction with other micrometeorological variables.

  11. Evaluation of spray drift using low speed wind tunnel measurements and dispersion modeling

    Science.gov (United States)

    The objective of this work was to evaluate the EPA’s proposed Test Plan for the validation testing of pesticide spray drift reduction technologies (DRTs) for row and field crops, focusing on the evaluation of ground application systems using the low-speed wind tunnel protocols and processing the dat...

  12. Experiment about Drag Reduction of Bionic Non-smooth Surface in Low Speed Wind Tunnel

    Institute of Scientific and Technical Information of China (English)

    Tian Li-mei; Ren Lu-quan; Han Zhi-wu; Zhang Shi-cun

    2005-01-01

    The body surface of some organisms has non-smooth structure, which is related to drag reduction in moving fluid. To imitate these structures, models with a non-smooth surface were made. In order to find a relationship be tween drag reduction and the non-smooth surface, an orthogonal design test was employed in a low speed wind tunnel. Six factors likely to influence drag reduction were considered, and each factor tested at three levels. The six factors were the configuration, diameter/bottom width, height/depth, distribution, the arrangement of the rough structures on the experimental model and the wind speed. It was shown that the non-smooth surface causes drag reduction and the distribution of non-smooth structures on the model, and wind speed, are the predominant factors affecting drag reduction. Using analysis of variance, the optimal combination and levels were obtained, which were a wind speed of 44 m/s, distribution of the non-smooth structure on the tail of the experimental model, the configuration of riblets, diameter/bottom width of 1 mm, height/depth of 0.5 mm, arranged in a rhombic formation. At the optimal combination mentioned above, the 99% confidence interval for drag reduction was 11.13 % to 22.30%.

  13. Process model for ammonia volatilization from anaerobic swine lagoons incorporating varying wind speeds and biogas bubbling

    Science.gov (United States)

    Ammonia volatilization from treatment lagoons varies widely with the total ammonia concentration, pH, temperature, suspended solids, atmospheric ammonia concentration above the water surface, and wind speed. Ammonia emissions were estimated with a process-based mechanistic model integrating ammonia ...

  14. Magneto switch microcircuit and wind speed measurement’s sensor on its base

    Directory of Open Access Journals (Sweden)

    Kasimov F. D.

    2009-04-01

    Full Text Available The magneto switch microcircuit on the base of Hall-effect is developed. The electric scheme of the magneto sensitive IC was designed and its basic technical characteristics are described. The gauge of wind speed on its base is fabricated.

  15. Control Method for Variable Speed Wind Turbines to Support Temporary Primary Frequency Control

    DEFF Research Database (Denmark)

    Wang, Haijiao; Chen, Zhe; Jiang, Quanyuan

    2014-01-01

    This paper develops a control method for variable speed wind turbines (VSWTs) to support temporary primary frequency control of power system. The control method contains two parts: (1) up-regulate support control when a frequency drop event occurs; (2) down-regulate support control when a frequen...

  16. Modular Multilevel Converters Based Variable Speed Wind Turbines for Grid Faults

    DEFF Research Database (Denmark)

    Deng, Fujin; Liu, Dong; Wang, Yanbo

    2016-01-01

    The modular multilevel converter (MMC) becomes attractive in the medium- and high-power application with high modularity. In this paper, the MMC is proposed to be applied in the variable speed wind turbine (VSWT) based on the full-scale back-to-back (BTB) power converter, where the generator-side...

  17. Hurricane Imaging Radiometer Wind Speed and Rain Rate Retrievals during the 2010 GRIP Flight Experiment

    Science.gov (United States)

    Sahawneh, Saleem; Farrar, Spencer; Johnson, James; Jones, W. Linwood; Roberts, Jason; Biswas, Sayak; Cecil, Daniel

    2014-01-01

    Microwave remote sensing observations of hurricanes, from NOAA and USAF hurricane surveillance aircraft, provide vital data for hurricane research and operations, for forecasting the intensity and track of tropical storms. The current operational standard for hurricane wind speed and rain rate measurements is the Stepped Frequency Microwave Radiometer (SFMR), which is a nadir viewing passive microwave airborne remote sensor. The Hurricane Imaging Radiometer, HIRAD, will extend the nadir viewing SFMR capability to provide wide swath images of wind speed and rain rate, while flying on a high altitude aircraft. HIRAD was first flown in the Genesis and Rapid Intensification Processes, GRIP, NASA hurricane field experiment in 2010. This paper reports on geophysical retrieval results and provides hurricane images from GRIP flights. An overview of the HIRAD instrument and the radiative transfer theory based, wind speed/rain rate retrieval algorithm is included. Results are presented for hurricane wind speed and rain rate for Earl and Karl, with comparison to collocated SFMR retrievals and WP3D Fuselage Radar images for validation purposes.

  18. Measurements and Modelling of the Wind Speed Profile in the Marine Atmospheric Boundary Layer

    Science.gov (United States)

    Peña, Alfredo; Gryning, Sven-Erik; Hasager, Charlotte B.

    2008-12-01

    We present measurements from 2006 of the marine wind speed profile at a site located 18 km from the west coast of Denmark in the North Sea. Measurements from mast-mounted cup anemometers up to a height of 45 m are extended to 161 m using LiDAR observations. Atmospheric turbulent flux measurements performed in 2004 with a sonic anemometer are compared to a bulk Richardson number formulation of the atmospheric stability. This is used to classify the LiDAR/cup wind speed profiles into atmospheric stability classes. The observations are compared to a simplified model for the wind speed profile that accounts for the effect of the boundary-layer height. For unstable and neutral atmospheric conditions the boundary-layer height could be neglected, whereas for stable conditions it is comparable to the measuring heights and therefore essential to include. It is interesting to note that, although it is derived from a different physical approach, the simplified wind speed profile conforms to the traditional expressions of the surface layer when the effect of the boundary-layer height is neglected.

  19. Wind speed response of marine non-precipitating stratocumulus clouds over a diurnal cycle in cloud-system resolving simulations

    Directory of Open Access Journals (Sweden)

    J. Kazil

    2015-10-01

    Full Text Available Observed and projected trends in large scale wind speed over the oceans prompt the question: how might marine stratocumulus clouds and their radiative properties respond to future changes in large scale wind speed? Wind speed drives the surface fluxes of sensible heat, moisture, and momentum, and thereby acts on cloud liquid water path (LWP and cloud radiative properties. We present an investigation of the dynamical response of non-precipitating, overcast marine stratocumulus clouds to different wind speeds, all else equal. In cloud-system resolving simulations, we find that higher wind speed leads to faster boundary layer growth and stronger entrainment. The dynamical driver is enhanced buoyant production of turbulence kinetic energy (TKE from latent heat release in cloud updrafts. LWP is enhanced during the night and in the morning at higher wind speed, and more strongly suppressed later in the day. Wind speed hence accentuates the diurnal LWP cycle by expanding the morning – afternoon contrast. The higher LWP at higher wind speed does not, however, enhance cloud top cooling because in clouds with LWP ⪆ 50 g m−2, long wave emissions are very insensitive to LWP. This leads to the more general conclusion that in sufficiently thick stratocumulus clouds, additional boundary layer growth and entrainment due to a boundary layer moistening arises by stronger production of TKE from latent heat release in cloud updrafts, rather than from enhanced longwave cooling. We find furthermore that large scale wind modulates boundary layer decoupling. At nighttime and at low wind speed during daytime, it enhances decoupling in part by faster boundary layer growth and stronger entrainment, and in part because circulation driven by shear from large scale wind in the sub-cloud layer hinders vertical moisture transport between the surface and cloud base. With increasing wind speed, however, in decoupled daytime conditions, shear-driven circulation due

  20. Implementing Speed and Separation Monitoring in Collaborative Robot Workcells.

    Science.gov (United States)

    Marvel, Jeremy A; Norcross, Rick

    2017-04-01

    We provide an overview and guidance for the Speed and Separation Monitoring methodology as presented in the International Organization of Standardization's technical specification 15066 on collaborative robot safety. Such functionality is provided by external, intelligent observer systems integrated into a robotic workcell. The SSM minimum protective distance function equation is discussed in detail, with consideration for the input values, implementation specifications, and performance expectations. We provide analytical analyses and test results of the current equation, discuss considerations for implementing SSM in human-occupied environments, and provide directions for technological advancements toward standardization.