Rotational Speed Control Researching For PMSG-based Wind Energy Conversion System

Wind power is free, clean, and renewable. Wind energy is very abundant and widely distributed on earth. With the pressing situation of shortage of traditional energy and environmental pollution, to develop clean and renewable energy resources, especially wind energy is of prominent importance and it has become an important part of world's sustainable development strategy. Wind power generation technology is relatively mature, and wind power generation is one of the most prospective new energy developing programs. Control technology in wind power generation plays an increasingly important role. In order to maximize wind energy capture, this paper focus on rotational speed control research for PMSG (Permanent-magnet Synchronous Generator)-based wind energy conversion system (WECS) below rated wind speed, using gain scheduling and feedback linearization method.On the basis of the analysis of the system parts'characteristics, a third-order nonlinear equivalent model of PMSG-based wind energy conversion system was established. In order to ensure maximum energy capture below rated wind speed, and the nonlinear model is linearized around different operating points, optimal tracking controller and H∞robust controller are designed for each operating point, then optimal tracking gain scheduling controller and H_inf gain scheduling controller are obtained, using gain scheduling control with a stability preserving interpolation method. Simulation model was constructed in Matlab/Simulink. Simulation results verify the effectiveness of the proposed method.Feedback linearization method based on differential geometry can decouple and linearize system accurately in a wide range, which is different from local linearization method around working point. In order to capture maximum energy below rated wind speed, a PMSG-based wind power conversion control system, which feedback linearization method and optimal tracking control strategy was integrated, was designed. Simulation model was constructed in VisSim/ECD. Simulation results indicate the proposed control method can effectively implement maximum energy capture below rated wind speed, even if the wind speed changes in a large range.