Floating-body motion control by coupling an oscillating mass for wind turbine applications

This paper presents feedback control to suppress the oscillation of an floating offshore wind turbine, by attaching it to a device which can act as both an actuator moving a buoyant mass and an electric generator receiving energy from the mass. The feedback controller uses the displacement of the platform as a sensor measurement to command appropriate forces to the actuator for rejecting unmeasurable wave disturbance forces. With the simplifying assumption of the vertically-moving cylindrical platform and buoyant mass, a state-space model is obtained, and a linear quadratic Gaussian controller is designed based on the model. Simulation results demonstrate not only the efficiency of the proposed control method for mitigating the platform oscillation, but also for its potential benefit to capture wave energy.