Research On The Technologies Of Low Voltage Operation For Double-fed Wind Power Generation System

Wind energy as a renewable clean energy, is an important choice to solve the problemsof energy crisis and environmental pollution. With wind power generator capacity increasedcontinuously, the relationship between the wind turbine and power grid is becoming more andmore closely in the power system. In order to ensure the stable operation of power system,wind turbine should have the ability of low voltage operation in the conditions of powersystem fault when a large scale time of wind power operates to grid. Criteria for low voltageoperation of wind turbine has been developed in many countries. Our countries haveestablished the rules of the low voltage operation, and made mandatory provisions for lowvoltage operation of wind turbine.In this dissertation, object for the study is double-fed wind power system, and it studythe control method of double-fed wind power generator rotor-side and grid-side excitationconverter as well as low voltage operation technology research from the theoretical analysisand simulation verify. Firstly, it analyzed the operation mechanism of double-fed wind powergenerator, and established the mathematical model of double-fed wind turbine in the threephase static coordinate, and obtained the dynamic mathematical model of dq rotatingcoordinates by transformation and simplification. Secondly, on the basis of the dynamicmathematical model of dq rotating coordinate, it analyzed the improvement control strategybased on stator flux oriented, and doing the simulation research in Matlab/Simulink. Thirdly,itestablished both the mathematical model and equivalent circuit of grid-side converter, andanalyzed vector control strategy of the grid oriented voltage, and doing the simulationresearch in Matlab/Simulink. Finally, this dissertation analyzed the response characteristics ofdouble-fed wind turbine at low voltage. three kinds of rotor-side Crowbar protection circuitand two kinds of DC-side protection circuit are studied by comparison, and analyzed controlstrategy of protection circuit in the low voltage operation. It’s simulated and studied lowvoltage operation capability of double-fed wind power generator in which grid voltage dropeddifferent depth by in Matlab/Simulink.