Study On Intelligent Control System Of VSCF Doubly Fed Generator

Because of rich store, extensive distribution, free pollution and other superiorities, wind energy is rapidly developing in the world, and accelerated to develop the utilization of wind energy is the same target for the energy field.To utilize wind energy is to generate electricity, of which utilization will resolve those problems such as energy shortage, environment pollution and greenhouse effects etc, therefore is a kind of ideal alternative energy source for conventional energies.Variable-speed constant-frequency generation technology is regarded as the best control way, and also as the main developing direction. Its advantages are that widely range speed control can adapt to the change of wind turbine due to the change of wind speed, greatest absorb wind energy, so its efficiency is high, and it is the important study task in the wind power generation field of inland.In the paper, first based on the analysis of the operation principle of the wind turbine and doubly fed generator, the mathematical model is respectively built. It set a foundation for the excited control system model of wind power system.Furthermore the effect of excited voltage on flux and electromagnetic torque of doubly fed generator is deduced under the rotor synchronous rotating reference frame, and the basic control principle of the doubly fed generator direct torque control excited control system is discussed. The simulation models of wind turbine, doubly fed generator and control mode are built, the simulations are analyzed. The simulation results suggest that the model is reliable, which conduces to the study on doubly fed excitation strategy and the design on the rotor excitation control system.Because PID controller of the traditional direct torque control system have a few of defeats , the sliding mode variable structure control theory is combined with the direct torque control system of doubly fed generator, the robustness of control system is improved and the sensitivity which due to the interference from the outside and variation of the system characteristic is reduced. A new sliding mode speed controller and a sliding mode flux estimatorare designed, the simulation results show that electromagnetic torque can well follow the input mechanical torque, and estimated flux precision also be improved.