Analytical model for the power production of a yaw-misaligned wind turbine

Abstract

Wake steering has proven to be effective in enhancing the power output of a wind farm. However, this approach still highly relies on empirical formulas to predict the power production of yawed turbines, limiting its potential in practical applications. In this study, an analytical model is proposed to predict the power production of a yaw-misaligned turbine under uniform inflow conditions. The model is based on the combination of the blade element theory and the momentum theory, with a modification in the latter to account for the disturbance on the spanwise velocity caused by the yawed turbine. A series of large eddy simulations were performed using a utility-scale wind turbine operating at yaw angles |γ|≤30° and tip-speed ratios λ=5–8. The validity of the proposed model is confirmed by the good agreement between the theoretical predictions and the simulation data. Furthermore, the well-known cosine model is shown to describe well the power production of the yawed turbine within the studied parameter range. However, the power-yaw loss exponent is not a constant, but rather a function of the tip-speed ratio. These findings may be useful in yaw optimization and control strategies in wind farms.