Control-oriented physics-based models for floating offshore wind turbines

This paper proposes a general control-oriented non-linear model for floating offshore wind turbine systems. It contains as many as six platform degrees of freedom as well as the rotor degree of freedom, and can account for full field wind and wave disturbances. Additionally, it accepts individual blade pitch, generator torque and yaw control inputs. The model is derived by assuming that the entire structure behaves as a single rigid body, under the influence of various forces and torques. Furthermore, it can be linearized analytically, making the wave disturbance matrix obtainable. We validate the proposed nonlinear model with advanced simulator FAST. Finally, we derive a simple LPV model from the proposed non-linear model.