Nonlinear dynamic inversion approach applied to pitch control of wind turbines

This paper presents a dynamic inversion approach for nonlinear pitch control of the WTs operating in the above-rated wind speed region, which will improve the generator rotor speed control for power generation and reduce the tower loads for the vibration reduction. The proposed controller consists of a rotor speed regulator, a tower load damper and a lead compensator. The rotor speed regulator and the load damper are designed independently using dynamic inversion approach to deal with the non-affine nonlinearity of the model, and the lead compensator is used to compensate for the phase lag of the pitch angle command caused by the pitch actuator. The simulation results with FAST verify the superiority of the proposed control scheme. Compared to the gain scheduled PI (GSPI) controller, the proposed nonlinear controller is able to improve the rotor speed control performance and reduce the tower loads effectively. Moreover, the proposed controller can work well for the whole above-rated wind speed region, and is simple to implement for application.