A Numerical Study on the Impact of Wake Steering on Ultimate Loads of Downstream Wind Turbines

There is an inherent dilemma in the synthesis of any wind farm control: optimizing farm power output must not lead turbines to operate under conditions in which excessive loading is expected. Wake steering-based control techniques, recognized as a highly effective means of increasing farm output, are no exception. In fact, the potential increase in fatigue and ultimate loads associated with the large misalignment operations prescribed by wake steering represents a source of concern, especially for machines that were not originally certified to operate under such conditions. The purpose of this work is to analyze and evaluate the impact of wake steering on ultimate loads and maximum deflections of a pair of upstream and downstream turbines, with a specific focus on cases involving the Extreme Operating Gust and Extreme Coherent gust with Direction change. The study is based on a simulation campaign using a reference 5-MW turbine. Results show that the maximum loads experienced by a waked downstream turbine during these extreme events do not exceed the maximum loads on the upstream turbine, even when both turbines operate under yawed conditions.