Study on wind turbine wake effect and analytical model in hilly terrain

Understanding and predicting turbine wake effect is crucial for the development of wind farms. Most existing studies have primarily focused on flat terrain, resulting in a lack of analytical modeling of turbine wake in complex terrain. This study systematically investigates the time-averaged flow and turbulent behavior of the turbine in complex terrain using large eddy simulations (LES). It is found that the vertical and horizontal velocity components induced by the terrain can cause the turbine wake deflect, while changes in the pressure gradient affect the velocity recovery of the turbine wake. The velocity deficit of the turbine wake in complex terrain largely conforms to a Gaussian distribution. Additionally, the common practice of superimposing the turbine wake velocity deficit from flat terrain onto the terrain wind field cannot accurately predict the wake velocity distribution and power performance of the turbine in complex terrain. A new turbine wake model is proposed considering the wake deflection and variations in velocity deficit, in order to accurately predict the wake velocity distribution and power generation. The analysis reveals a significant improvement, with reductions in the maximum error of the average velocity at the turbine rotor plane and estimated power generation by 18 % and 31 %, respectively.