Wake meandering of wind turbines under dynamic yaw control and impacts on power and fatigue

Abstract

In this study, we use large-eddy simulation (LES) to investigate the wake-meandering phenomenon within a wind turbine array under dynamic yaw control (DYC) and the effects on power and fatigue. The wind turbine array consists of eight NREL 5-MW reference turbines aligned with the inflow direction. The first turbine in the array is subjected to sinusoidal yaw control with a magnitude of 10∘ and different yaw frequencies. Based on spectral and dynamic-mode-decomposition (DMD) analyses of the flow fields, we find that the wake meandering within the turbine array is significantly amplified when the turbine yaw frequency coincides with the natural wake meandering frequency of the turbine array in the static zero-yaw condition. The resonance of wake meandering accelerates wake recovery and helps the turbine array achieve an optimal power gain (5% with respect to the non-yaw baseline cases). We also find that the fatigue of the turbine array overall increases with the yaw frequency of the first turbine, highlighting the necessity of jointly considering power production and fatigue when applying DYC.