Controlling A Meandering Wake: Insights From Full-Information Control

In this paper we design and analyze a full-information H-infinity controller to in order to reduce the wake meandering behind a wind turbine. The low frequency instability that causes wake meandering can cause unsteady mechanical loads on the downstream turbines resulting in early onset of material fatigue. Controlling the wake meandering in a wind farm can therefore reduce maintenance costs. The control design and analysis in this paper proceeds in two steps. First, a linear reduced order model of the turbine is obtained using snapshots from a higher-order nonlinear 2D actuator-disk model. A full-information H-infinity controller is then designed for the reduced order model assuming access to the entire flow field and disturbance input. The control performance is evaluated by simulations on the higher-order nonlinear model. The full-information controller can not be implemented in practice. However, it can provide insight into control design for wind farms such as identifying desirable locations to measure the downstream flow.