Research On The Decoupled Control Policy Of Active And Reactive Power Of Wind Power Generation System Based On Doubly-Fed Induction Generator

To exploit and use renewable energy is an imperative choice to settle energy crisis and serious environmental pollution problems caused by the eventually exhausted traditional energy such as petroleum and natural gas. As the world’s fastest growing renewable energy, Wind power can be massively developed and utilized and has a good market prospect in renewable energy technology. Double-fed induction generator(DFIG)wind power system has the advantages of low cost, variable speed constant frequency operation, small slip power, stable operation which make it become the most widely used type of wind turbine.It is particularly suitable to be used in the environment of random wind.Such work as operating principle analysis and modeling, power decoupling control strategy, maximum wind energy capture control, quick no-load cutting-in,System Modeling and Simulation Analysis are done on DFIG. Operation mechenism and the Maximum Power Persuing Technology(MPPT) of wind turbine is analyzed in detail. The nonlinear theory and slide-mode variable structure control theory are introducted. The motor’s mathematical model in d-q synchronous rotating reference frame is deduced based on the model in three-phase stationary reference frame. For the purposes of decoupling active power and reactive power completely and mild no-load cutting-in power system,based on MPPT algorithm, nonlinear system and slide-mode variable structure control theory are combined to design the robust power decoupling control law for variable speed constant frequency (VSCF) wind power generation and to realize mild no-load cutting in power system.The simulation results show that this control method can completely decouple active power and reactive power.realize the maximum power persuing technology (MPPT) control and realize quick and mild no-load cutting-in power system.The stator makes a smaller strike to grid and the rotator current has a steady convertion in the transition period.Compared with the traditonal vector and PI control method.the proposed control method has better decoupling effect and more rapid dynamic and static response, meanwhile,under the condition of machine inner parameters uncertainty and external interference, it has robust result.