Load Mitigation for a Floating Wind Turbine via Generalized H∞ Structural Control

Active structural control is a promising and effective approach to load reduction of floating wind turbines. This paper investigates use of active structural control to mitigate loads of a floating wind turbine on a barge platform. Different from the existing results, static output feedback is employed as the control law for reducing implementation complexity while a turned mass damper is considered to be installed on the platform instead of in the nacelle. To design active structural controllers, first an input-output linear design model for the wind turbine is identified from time response data, and then an advanced generalized H-infinity method is employed for optimizing the controller gain so as to reduce wave induced loads. Through high-fidelity simulation results of the wind turbine, it is found that the designed active controllers could further reduce the main fatigue load and the generator power error, but the standard H-infinity one is not economical and lacks enough reliability. The ratinale of the generalized H-infinity method in trading off load reduction and controller gain reduction is also discussed.