In this paper,studies on offshore wind farm wakes observed by spaceborne synthetic aperture radar(SAR)are reviewed mainly based on our previous research.Particularly,we focus on investigating wind wakes and tidal curr...In this paper,studies on offshore wind farm wakes observed by spaceborne synthetic aperture radar(SAR)are reviewed mainly based on our previous research.Particularly,we focus on investigating wind wakes and tidal current wakes observed by spaceborne SAR of Terra SAR-X,Gaofen-3 and Radarsat-2 in high spatial resolution,in two offshores wind farms,i.e.,the Alpha Ventus in the North Sea and the one near Donghai bridge in the East China Sea.Representing examples of wind wakes and tidal current wakes observed by SAR in the two farms are presented and compared.A preliminary statistical analysis on morphology of wind feature downstream Alpha Ventus is presented as well.Besides these studies on wind wakes generated by a single offshore wind farm,we show an example of wakes downstream multiple wind farms in the North Sea to demonstrate"cluster"effect of multiple offshore wind farms on sea wind.展开更多
With the increased penetration of wind energy in our nation’s energy portfolio, wind farms are placed in a way close to each other. Thus, their wakes have to be fully considered in the design and operation of a wind ...With the increased penetration of wind energy in our nation’s energy portfolio, wind farms are placed in a way close to each other. Thus, their wakes have to be fully considered in the design and operation of a wind farm. In this study, we investigate the wake of a wind farm using large-eddy simulation with wind turbine rotor modelled by the actuator disk model. The simulated results show that the wake of a wind farm can persist for a long distance in its downstream. For the considered wind farm layout, the velocity in the wake recovers 95% of that of the undisturbed inflow at 55 rotor diameters downstream from its last row, suggesting that the wake of a wind farm should be fully considered in the optimal design and operation for its downstream wind farms.展开更多
The influence of wake parameters on the exergy analysis of single array wind farm is studied in this paper. Key parameters which influence wake effects in a wind farm are wind velocity, tip speed ratio, number of blad...The influence of wake parameters on the exergy analysis of single array wind farm is studied in this paper. Key parameters which influence wake effects in a wind farm are wind velocity, tip speed ratio, number of blades, rotor speed, rotor diameter and hub height. Three different models namely power, wake and exergy model were used in estimating the exergy efficiency of the single array wind farm. Even though it is ideal for wind farms to fix the wind turbines in rows and columns the conditions of the site may not always be condu- cive for it. Hence analysis has been done keeping the wind turbines at random in a row and the effect of positioning on the performance is analyzed. Energy and exergy efficiency calculations were made for different cases by varying the positions of wind turbines in the single array wind farm. Standard relations were used in estimating the energy deficit in the wind farm due to wake effects. The wake effects were found to have an aggregated influence on the energy production of the wind farm, which results from the changes in the key parameters mentioned above. Potential areas for reducing energy losses by proper location and selection of turbines based on rating are highlighted. The influence of individual parameters contributing to the wake ef-fect were analyzed and discussed in detail.展开更多
We use the Wind Farm Parameterization(WFP) scheme coupled with the Weather Research and Forecasting model under multiple resolution regimes to simulate turbulent wake dynamics generated by a real onshore wind farm and...We use the Wind Farm Parameterization(WFP) scheme coupled with the Weather Research and Forecasting model under multiple resolution regimes to simulate turbulent wake dynamics generated by a real onshore wind farm and their influence at the local meteorological scale. The model outputs are compared with earlier modeling and observation studies. It is found that higher vertical and horizontal resolutions have great impacts on the simulated wake flow dynamics. The corresponding wind speed deficit and turbulent kinetic energy results match well with previous studies. In addition, the effect of horizontal resolution on near-surface meteorology is significantly higher than that of vertical resolution. The wake flow field extends from the start of the wind farm to downstream within 10 km, where the wind speed deficit may exceed 4%. For a height of 150 m or at a distance of about 25 km downstream, the wind speed deficit is around 2%. This indicates that, at a distance of more than 25 km downstream, the impact of the wind turbines can be ignored. Analysis of near-surface meteorology indicates a night and early morning warming near the surface, and increase in near-surface water vapor mixing ratio with decreasing surface sensible and latent heat fluxes. During daytime, a slight cooling near the surface and decrease in the near-surface water vapor mixing ratio with increasing surface sensible and latent heat fluxes is noticed over the wind farm area.展开更多
降低风电场出力波动性有利于促进电网友好运行,而尾流优化控制是降低整场出力波动的重要措施。现有尾流优化控制大都基于稳态模型,却忽略尾流动态迟延特性。但尾流迟延在风速不确定性基础上会进一步增加风电场出力的波动性。为此,该文...降低风电场出力波动性有利于促进电网友好运行,而尾流优化控制是降低整场出力波动的重要措施。现有尾流优化控制大都基于稳态模型,却忽略尾流动态迟延特性。但尾流迟延在风速不确定性基础上会进一步增加风电场出力的波动性。为此,该文基于稳态尾流模型辅以迟延计算,构建风电场准稳态尾流模型以同时兼顾尾流干涉作用与动态迟延特性。在此基础上,提出一种考虑迟延的模型预测平稳控制方法(predictive control considering delay,MPC-D),以指令跟踪与功率波动最小为目标协调各机组出力。最后,在WFSim上构建含33台机组的风电场仿真模型,并基于此分析尾流迟延对风电机组以及整场运行性能影响。结果表明,所建准稳态尾流模型能同时模拟尾流速度损失、机组功率迟延和整场功率阶梯变化等特性。并且由MPC-D所得整场出力较基于稳态模型的控制方法平均相对误差、均方根误差以及滑动均方根误差均得到改善,同时能防止机组桨距角频繁动作。展开更多
基金Natural Science Foundation of Hainan Province(No.420RC675)National Natural Science Foundation of China(No.41471309)。
文摘In this paper,studies on offshore wind farm wakes observed by spaceborne synthetic aperture radar(SAR)are reviewed mainly based on our previous research.Particularly,we focus on investigating wind wakes and tidal current wakes observed by spaceborne SAR of Terra SAR-X,Gaofen-3 and Radarsat-2 in high spatial resolution,in two offshores wind farms,i.e.,the Alpha Ventus in the North Sea and the one near Donghai bridge in the East China Sea.Representing examples of wind wakes and tidal current wakes observed by SAR in the two farms are presented and compared.A preliminary statistical analysis on morphology of wind feature downstream Alpha Ventus is presented as well.Besides these studies on wind wakes generated by a single offshore wind farm,we show an example of wakes downstream multiple wind farms in the North Sea to demonstrate"cluster"effect of multiple offshore wind farms on sea wind.
基金supported by the National Natural Science Foundation of China(Nos.11988102,12172360)Institute of Mechanics and Chinese Academy of Sciences。
文摘With the increased penetration of wind energy in our nation’s energy portfolio, wind farms are placed in a way close to each other. Thus, their wakes have to be fully considered in the design and operation of a wind farm. In this study, we investigate the wake of a wind farm using large-eddy simulation with wind turbine rotor modelled by the actuator disk model. The simulated results show that the wake of a wind farm can persist for a long distance in its downstream. For the considered wind farm layout, the velocity in the wake recovers 95% of that of the undisturbed inflow at 55 rotor diameters downstream from its last row, suggesting that the wake of a wind farm should be fully considered in the optimal design and operation for its downstream wind farms.
文摘The influence of wake parameters on the exergy analysis of single array wind farm is studied in this paper. Key parameters which influence wake effects in a wind farm are wind velocity, tip speed ratio, number of blades, rotor speed, rotor diameter and hub height. Three different models namely power, wake and exergy model were used in estimating the exergy efficiency of the single array wind farm. Even though it is ideal for wind farms to fix the wind turbines in rows and columns the conditions of the site may not always be condu- cive for it. Hence analysis has been done keeping the wind turbines at random in a row and the effect of positioning on the performance is analyzed. Energy and exergy efficiency calculations were made for different cases by varying the positions of wind turbines in the single array wind farm. Standard relations were used in estimating the energy deficit in the wind farm due to wake effects. The wake effects were found to have an aggregated influence on the energy production of the wind farm, which results from the changes in the key parameters mentioned above. Potential areas for reducing energy losses by proper location and selection of turbines based on rating are highlighted. The influence of individual parameters contributing to the wake ef-fect were analyzed and discussed in detail.
基金the National Key Research and Development Program of China (Grant No.2017YFA0604501)the National Natural Science Foundation of China (Grant No.41475013) for the funding support
文摘We use the Wind Farm Parameterization(WFP) scheme coupled with the Weather Research and Forecasting model under multiple resolution regimes to simulate turbulent wake dynamics generated by a real onshore wind farm and their influence at the local meteorological scale. The model outputs are compared with earlier modeling and observation studies. It is found that higher vertical and horizontal resolutions have great impacts on the simulated wake flow dynamics. The corresponding wind speed deficit and turbulent kinetic energy results match well with previous studies. In addition, the effect of horizontal resolution on near-surface meteorology is significantly higher than that of vertical resolution. The wake flow field extends from the start of the wind farm to downstream within 10 km, where the wind speed deficit may exceed 4%. For a height of 150 m or at a distance of about 25 km downstream, the wind speed deficit is around 2%. This indicates that, at a distance of more than 25 km downstream, the impact of the wind turbines can be ignored. Analysis of near-surface meteorology indicates a night and early morning warming near the surface, and increase in near-surface water vapor mixing ratio with decreasing surface sensible and latent heat fluxes. During daytime, a slight cooling near the surface and decrease in the near-surface water vapor mixing ratio with increasing surface sensible and latent heat fluxes is noticed over the wind farm area.
文摘降低风电场出力波动性有利于促进电网友好运行,而尾流优化控制是降低整场出力波动的重要措施。现有尾流优化控制大都基于稳态模型,却忽略尾流动态迟延特性。但尾流迟延在风速不确定性基础上会进一步增加风电场出力的波动性。为此,该文基于稳态尾流模型辅以迟延计算,构建风电场准稳态尾流模型以同时兼顾尾流干涉作用与动态迟延特性。在此基础上,提出一种考虑迟延的模型预测平稳控制方法(predictive control considering delay,MPC-D),以指令跟踪与功率波动最小为目标协调各机组出力。最后,在WFSim上构建含33台机组的风电场仿真模型,并基于此分析尾流迟延对风电机组以及整场运行性能影响。结果表明,所建准稳态尾流模型能同时模拟尾流速度损失、机组功率迟延和整场功率阶梯变化等特性。并且由MPC-D所得整场出力较基于稳态模型的控制方法平均相对误差、均方根误差以及滑动均方根误差均得到改善,同时能防止机组桨距角频繁动作。