Active disturbance rejection power control for a floating wind turbine

In recent years, a feasible scheme has been provided by the floating wind turbine for wind power generation changing from the coastal sea to the deep sea. However, the stability of the floating wind turbine power output is seriously influenced by the uncertainty of the model and the external disturbances like wind and wave. Therefore, a power control method for floating wind turbine based on active disturbance rejection (ADR) is proposed in this paper. The purpose of the controller is to avoid increasing the platform load caused by the power regulation on the premise of guaranteeing the stability of power output. Firstly, in order to avoid the large overshoot of the system, the step input signal is transformed into a continuous and smooth signal by designing the tracking differentiator. Secondly, a nonlinear observer is designed to estimate and compensate the unknown time varying nonlinear and disturbances in the system online. Finally, the pitch control is realized by the conventional PD controller. The proposed control approach is tested and compared with NREL baseline controller using the NREL offshore 5MW wind turbine model mounted on a Barge floating platform run on FAST and Matlab/Simulink, operating in the above-rated wind speed condition. The simulation results show that the proposed control strategy has a better performance on floating wind turbine power control.