The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform
Michel Verhaegen - One of the best experts on this subject based on the ideXlab platform.
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on the proof of concept of a smart wind turbine Rotor blade for load alleviation
Wind Energy, 2008Co-Authors: J W Van Wingerden, A W Hulskamp, Thanasis K Barlas, B Marrant, G A M Van Kuik, D P Molenaar, Michel VerhaegenAbstract:The trend with offshore wind turbines is to increase the Rotor diameter as much as possible to decrease the costs per kilowatt-hour. The increasing dimensions have led to the relative increase of the loads on the wind turbine structure. Because of the increasing Rotor Size and the spatial load variations along the blade, it is necessary to react to turbulence in a more detailed way; each blade separately and at several separate radial distances. In this paper, a proof of concept study is performed to show the feasibility of the load alleviation abilities of a ‘Smart’ blade, i.e. a blade equipped with a number of control devices that locally change the lift profile on the blade, combined with appropriate sensors and feedback controllers. Theoretical and experimental models are developed of a scaled non-rotating Rotor blade which is equipped with two trailing edge flaps and strain sensors to facilitate feedback control. A pitch actuator is used to induce disturbances with a similar character as a gust or turbulence. A feedback controller based on classical loop shaping is designed that minimizes the root bending moment in the flapping direction. We show that with appropriate control techniques, the loads for periodic disturbances and for turbulence generated disturbances can be reduced up to 90 and 55%, respectively. Copyright © 2008 John Wiley & Sons, Ltd.
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On the proof of concept of a ‘Smart’ wind turbine Rotor blade for load alleviation
Wind Energy, 2008Co-Authors: J W Van Wingerden, A W Hulskamp, Thanasis K Barlas, B Marrant, G A M Van Kuik, D P Molenaar, Michel VerhaegenAbstract:The trend with offshore wind turbines is to increase the Rotor diameter as much as possible to decrease the costs per kilowatt-hour. The increasing dimensions have led to the relative increase of the loads on the wind turbine structure. Because of the increasing Rotor Size and the spatial load variations along the blade, it is necessary to react to turbulence in a more detailed way; each blade separately and at several separate radial distances. In this paper, a proof of concept study is performed to show the feasibility of the load alleviation abilities of a ‘Smart’ blade, i.e. a blade equipped with a number of control devices that locally change the lift profile on the blade, combined with appropriate sensors and feedback controllers. Theoretical and experimental models are developed of a scaled non-rotating Rotor blade which is equipped with two trailing edge flaps and strain sensors to facilitate feedback control. A pitch actuator is used to induce disturbances with a similar character as a gust or turbulence. A feedback controller based on classical loop shaping is designed that minimizes the root bending moment in the flapping direction. We show that with appropriate control techniques, the loads for periodic disturbances and for turbulence generated disturbances can be reduced up to 90 and 55%, respectively. Copyright © 2008 John Wiley & Sons, Ltd.
Janusz Telega - One of the best experts on this subject based on the ideXlab platform.
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Variable Size Twin-Rotor Wind Turbine
Energies, 2019Co-Authors: Piotr Doerffer, Krzysztof Doerffer, Tomasz Ochrymiuk, Janusz TelegaAbstract:The paper presents a new concept of a vertical axis wind turbine. The idea is focused on small wind turbines, and therefore, the dominating quality is safety. Another important necessary feature is efficient operation at small winds. This implies an application of the drag driven solution such as the Savonius Rotor. The presented concept is aimed at reducing the Rotor Size and the cost of implementation. A new wind turbine solution, its efficiency, and functionality are described. The results of numerical simulations being a proof of the concept are reported. The simulations were followed by wind tunnel tests. Finally several prototypes were built and investigated for a longer period of time. The new wind turbine concept has undergone various testing and implementation efforts, making this idea matured, well proven and documented. A new feature, namely, the wind turbine Size reduction at strong winds, or in other words, an increase in the wind turbine Size at low winds is the reason why it is difficult to compare this turbine with other turbines on the market. The power output depends not only on the turbine efficiency but also on its varying Size.
Rafiuddin M Ahmed - One of the best experts on this subject based on the ideXlab platform.
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blade design and performance testing of a small wind turbine Rotor for low wind speed applications
Renewable Energy, 2013Co-Authors: Ronit K Singh, Rafiuddin M AhmedAbstract:Small wind turbines operating at low wind speeds regularly face the problem of poor performance due to laminar separation and laminar separation bubbles on the blades. This is due to the low Reynolds number (Re) resulting from low wind speeds and small Rotor Size. The use of specially designed low Re airfoils permits start up at lower wind speeds, increasing the startup torque and thus improving the overall performance of the turbine. A new airfoil was designed and the performance of a 2-bladed Rotor designed for low Re application fitted to an Air-X marine 400 W wind turbine was tested at a wind speed range of 3–6 m/s. The low Re Rotor incorporated taper and twist to the low Re AF300 airfoil section. The pitch of the blades was varied over a range of 15°, 18° and 20° to study the performance and the startup wind speed. It was found that the turbine performed best at 18° pitch angle. On an average, the wind turbine yielded a power coefficient (CP) of 0.255 at a height of 8.22 m at a wind speed of 6 m/s at 18° pitch angle. Maximum CP based on 10 s data at the freestream velocity of 6 m/s was 0.291. The cut-in wind speed based on 10 s averaged data at the optimum pitch angle was 3.24 m/s whereas the instantaneous cut-in wind speed was 2.34 m/s. In comparison with the baseline 3-bladed Rotor, the new 2-bladed Rotor produced more electrical power at the same freestream velocity.
Jan Abraham Ferreira - One of the best experts on this subject based on the ideXlab platform.
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Comparison of Energy Yield of Small Wind Turbines in Low Wind Speed Areas
IEEE Transactions on Sustainable Energy, 2013Co-Authors: S. O. Ani, Henk Polinder, Jan Abraham FerreiraAbstract:The objective of this paper is to compare the energy yield and generated electricity cost of several commercially available small wind turbines under low wind speed condition. Many small wind turbines were not able to generate the amount of electricity promised by the manufacturers. The predicted annual energy yield simulated using manufacturers' power curve were sometimes higher than actual measured values by up to a factor of two. Furthermore, above a Rotor Size of 3 m, large diameter turbines performed better, having both low generated electricity cost ( € /kWh) and high annual energy yield per swept area (kWh/m 2).
Martin Odening - One of the best experts on this subject based on the ideXlab platform.
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Neighborhood Effects in Wind Farm Performance: A Regression Approach
Energies, 2017Co-Authors: Matthias Ritter, Simone Pieralli, Martin OdeningAbstract:The optimization of turbine density in wind farms entails a trade-off between the usage of scarce, expensive land and power losses through turbine wake effects. A quantification and prediction of the wake effect, however, is challenging because of the complex aerodynamic nature of the interdependencies of turbines. In this paper, we propose a parsimonious data driven regression wake model that can be used to predict production losses of existing and potential wind farms. Motivated by simple engineering wake models, the predicting variables are wind speed, the turbine alignment angle, and distance. By utilizing data from two wind farms in Germany, we show that our models can compete with the standard Jensen model in predicting wake effect losses. A scenario analysis reveals that a distance between turbines can be reduced by up to three times the Rotor Size, without entailing substantial production losses. In contrast, an unfavorable configuration of turbines with respect to the main wind direction can result in production losses that are much higher than in an optimal case.
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Neighborhood Effects in Wind Farm Performance: An Econometric Approach
2016Co-Authors: Matthias Ritter, Simone Pieralli, Martin OdeningAbstract:The optimization of turbine density in wind farms entails a trade-off between the usage of scarce, expensive land and power losses through turbine wake effects. A quantification and prediction of the wake effect, however, is challenging because of the complex aerodynamic nature of the interdependencies of turbines. In this paper, we propose a parsimonious data driven econometric wake model that can be used to predict production losses of existing and potential wind parks. Motivated by simple engineering wake models, the predicting variables are wind speed, turbine alignment angle, and distance. By utilizing data from two wind parks in Germany, a significantly better prediction of wake effect losses is attained compared to the standard Jensen model. A scenario analysis reveals that a distance between turbines can be reduced up to three times the Rotor Size without entailing substantial production losses. In contrast, a suboptimal configuration of turbines with respect to the main wind direction can result in production losses that are five times higher.
