Preliminary Estimates of Wind Energy Resources Deficit in Large Wind Farm

The assessment of wind energy resource plays a fundamental role in its exploitation.The assessment should take into account the influence of wind turbines on the current within the wind farm in the surface layer.An area of approximately 2 000 km2 with a roughness length of 0.03 m in large wind farm is idealized.6 667 typical wind turbines about one million kilowatts are distributed uniformly over the area.The Frandsen method is used to analyze the influence of wind farm on the wind energy resources within the area where the internal boundary layer has filled the whole boundary layer in the wind farm.The results show that the wind speed at the height of 65 m will decrease when the situation with the presence of the wind farms is taken.This reduction becomes less when the wind speed at the height of 65 m increases,due to the property of drag coefficient in wind turbine.Within the wind speed range of 3~20 m·s-1 at the height of 65 m,the average wind power density considering the situation without and with wind farms are calculated,respectively.And the value decreases 58.45% when the wind farm is installed.