A Novel Constant Output Powers Compound Control Strategy for Variable-Speed Variable-Pitch Wind Turbines

The output power of wind turbine should be maintained at rated value when wind speed exceeds rated speed. However, the wind turbine is a system with large nonlinearity and time delay. Therefore, it is difficult for conventional linear controllers to realize effective control. In order to solve this problem, a combination of feedforward control with feedback control is developed. In feedback loop, feedback linearization theory is adopted to overcome the nonlinear features, and sliding mode algorithm is employed to improve the robustness of the system. On the other hand, in feedforward loop, a cerebellar model articulation controller is implemented to approximate the system. Furthermore, an improved credit assignment method is used to adjust the weight of the network. Together these procedures improve the effectiveness of the algorithm. Through this method, not only can the stability of the nonlinear model be ensured, but also the control lag caused by the time-delayed system can be compensated. Simulation results show that the feedforward-feedback compound control algorithm can both keep the output power at rated value and improve dynamic response speed, reduce adjustment time, has small steady-state error.