Mesoscale impact of the sea surface on the performance of offshore wind farms

Abstract

The impact of the ocean on the performance of offshore wind farms is a challenging study in the wind energy field. In the present study, by coupling a mesoscale numerical weather prediction model, Weather Research and Forecasting (WRF), with a sea surface model and a refined wind farm parameterization, a systematic atmosphere-sea surface-wind farm simulation method is established. The question of how the ocean-atmosphere interaction changes the wake effect and power output of wind farms based on the method is explored. The results show that the momentum deficit due to the operating wind turbines is remarkable, and the wind speed deficit has a strong horizontal diffusion on a sea surface. Wake from the offshore wind farm is prone to mix and extends with a shorter length than that on the flat land. The wake mixing enhances the interference from upwind to downwind turbines, resulting in the power outputs of downwind turbines being decreased by 10%. Besides, the increasing wind shear due to the ocean waves decreases the wind power by around 3.5%. Accordingly, it is significant for applying such a coupled air-sea surface-wind farm simulation method when assessing the offshore wind farm performance and the impact of the wind farms on the marine atmospheric boundary layer.