Novel yaw-based wake modelling and controlling to enhance the power output of floating offshore wind farms

Wind farms experience considerable power losses due to wake effects. Intentional yaw misalignment is a promising control technology for enhancing the efficiency of wind farms by redirecting the wake of upstream wind turbines. By applying a skewed cosine distribution to modify the conventional wake velocity profiles, a novel wake model for yawed wind turbines is proposed to predict the wake deflection and full-field wake velocity distribution. The derived model is validated through data from wind-tunnel experiments and large-eddy simulations. The comparisons with existing wake models reveal its superior accuracy in predicting yaw-induced wake deflection and asymmetric velocity distributions across both near and far wakes. A novel control strategy that expands the controllable deflection range of wakes is developed for a multi-turbine floating platform by combining platform yaw control with wind turbine yaw control, named the Dual Yaw Control Strategy (DYCS). The performance of DYCS is investigated through two cases, demonstrating that the DYCS can significantly improve the power output of the wind farm under severe effects of wakes compared to either yaw control alone, and shows effectiveness under realistic wind regimes. The optimal yaw angle of turbines varies around a fixed angle under different platform yaw angles. The efficiency at the optimal yaw angle is increased with enlarged platform yaw angle. The enhancement of wind farm output is up to 11.3% in the best case. These results indicate that the DYCS holds considerable potential for applications in the power optimization of floating offshore wind farms.