Experimental investigation of wind turbine wake and load dynamics during yaw manoeuvres

Abstract

Abstract. This paper investigates the effect of yawing a wind turbine on its wake deviation dynamics and on the global load variation of a downstream wind turbine during a positive and negative yaw manoeuvre, representing a misalignment/realignment scenario. Yaw manoeuvres could be used to voluntarily misalign wind turbines when wake steering control is targeted. The aim of this wind farm control strategy, which is increasingly studied, is to optimize the overall production of the wind farm and possibly its lifetime, by mitigating wake interactions. Whereas wake flow and wind turbine load dynamics during yaw manoeuvres are usually approached by quasi-static models, the present study aims at quantifying dynamical properties of these phenomena. Wind tunnel experiments were conducted in three different configurations, varying both scaling and flow conditions, in which the yaw manoeuvre was reproduced in a homogeneous turbulent flow at two different scales, and in a more realistic flow such as a modelled atmospheric boundary layer. The effects of yaw control on the wake deviation were investigated by the use of stereo Particle Imaging Velocimetry while the load variation on a downstream wind turbine was measured through an unsteady aerodynamic load balance. While overall results show a non dependence of the wake and load dynamics on the flow conditions and Reynolds scales, they highlight an influence of the yaw manoeuvre direction on their temporal dynamics.

Wake steering of multirotor wind turbines

“…Details of cross‐stream components of wake velocity have been examined by Martínez‐Tossas et al, 11 in which a ‘curled‐wake’ model is formulated, and by Shapiro et al, 12 in which yawed turbines are viewed as lifting lines. In recent developments, several wind tunnel studies (for example, 13‐16 ), numerical simulations (for example, 17‐20 ), as well as field studies (for example, 21‐26 ) have examined wake steering for wind farms of single‐rotor wind turbines, in which improvements have been seen in terms of both power output and reliability.…”