Parametric study of the effectiveness of active yaw control based on large eddy simulation

Abstract

Previous studies on active yaw control (hereafter, AYC) have demonstrated its potential in wind farm power optimization. However, most focus are concentrated on the amount of relative power enhancement achieved by AYC, ignoring how various parameters affect the effectiveness of AYC, let alone the mechanism behind the variation of AYC efficiency. Evidently, this is not conducive to the practical implementation of AYC. In response, a parametric study of the effectiveness of AYC is pursued in this paper, by performing a series of large eddy simulations (hereafter, LES) for the NREL 5 MW turbine array under different operating conditions. The LES results reveal that AYC is more effective in the environment with lower incoming wind speed and smaller turbulence intensity level. What is more, the AYC efficiency is found to vary greatly with the streamwise distance between consecutive wind turbines, but is not sensitive to the change of column spacing within a typical range. A large power gain is achieved at wind angles corresponding to partial-wake operating conditions. The active yaw behavior of the last wind turbine in the array also shows the potential to increase the total power production but the corresponding power gain is small. Moreover, it is shown that the yaw direction of wind turbine has nonnegligible influence on AYC, especially in the stable boundary layer. From the power production perspective, positive yaw of wind turbine is recommended in the north hemisphere.