Study On Application Of WindSim In Wind Energy Resources Assessment For Wind Farms In China

Wind energy resource assessment software WindSim based on Computational Fluid Dynamics (CFD) method is applied to simulate the wind energy resources of wind farm with different terrain in China. By comparing simulation results and observation data measured by anemometer towers, the reasons of differences between simulation results and observation data are analyzed and the simulation performance of WindSim for topography and climate in China are evaluated.First of all, when the anemometer tower located in the higher altitude and the terrain of funnelling is used as the input data, results show that WindSim provides good simulation results of effective wind speed(3~25m/s) frequency and poor results of low wind speed frequency in wind farm of complex terrain. Moreover, WindSim is able to accurately simulate the dominant wind direction at 70m height. WindSim can obtain good results of monthly mean wind speed of higher layers, but the simulation outcomes at 10m height is really disappointing. At the same time, when the anemometer tower located in the lower altitude area is used as the input data, the simulation results indicate that WindSim can accurately simulate effective wind speed frequency, high wind speed frequency and dominant wind direction, but can't exactly simulate the low wind speed frequency. Furthermore, the results of monthly mean wind speed at higher layers are better than the corresponding results which are received from the simulation when the anemometer tower located in the higher altitude and the terrain of funnelling is used as the input data. Consequently, the simulation results are better in agreement with observations when the site situated in a rather simple and representative area is used as the input data.In addition, the simulation results of wind energy resource in wind farm show that the area has well-distributed and rich wind energy resource which can be used by wind power generation. The results of yearly mean wind speed roughly reflect the terrain features. Moreover, the wind speeds at 70m height are higher than the wind speed at 50m height, as a result, we can gain the more wind energy production by raising the hub height.After that, we simulate the wind energy resource of flat terrain in China. Results show that WindSim provides good simulation results of effective wind speed (3~25m/s) frequency and low wind speed frequency, but software gives poor results of dominant wind direction in wind farm of flat terrain. In addition, the results of monthly mean wind speed in flat terrain are better than the corresponding results in complex terrain. At last, the simulation results of wind energy resource in wind farm also show that the area has well-distributed and rich wind energy resource which can be used by wind power generation. The wind speeds increase with the rising of height.Finally, the simulation results of wind energy production in wind farm of complex terrain show that the 4D×6D arrangement pattern is more suitable to this wind field and the appropriate hub heights of G52-850kW and G80-2000kW are 55m. By analyzing the wake effect of wind turbines located at the different sites in wind farm, it is shown that the arrangement pattern is supposed to be perpendicular to the dominant wind direction in order to weaken wake effect between the wind turbines to a maximum extent during the actual project.