Research On VSCF AC Excitation Doubly Fed Wind Energy Generation System

Shortages of energy have become increasingly prominent, the demand of electricity is growing. With the most environmentally clean energy source, wind energy, the great energy pressures will be eased. Compared with the general wind energy generation system, the conversion strategy of doubly-fed wind power generation system is operated in the rotor side. So the size of the conversion is small and its cost is low, the connection between mechanical and electrical is flexible. In this paper, doubly-fed VSCF wind power electrical system and its control strategy are discussed.This paper introduces the basic principles of wind power, how to capture the largest wind energy, and the nonlinear relation between wind energy utilization coefficient, tip speed ratio and blade pitch angle. Explain the relation between output power and speed. Simulate and compare the fixed pitch system and the changeable pitch system, finding that the pitch control strategy used to increase the output power.Illustrate the basic principle of double-fed motor. Derive the mathematical model of double-fed motor in the rotating coordinate and the equivalent circuit. Analyze the flow of power based on the equivalent circuit. Explain the stability of double-fed motor and obtain the stable condition.Introduce the principle of the rectifier. Establish the mathematical model of PWM rectifier. Decouple active and reactive power with the vector control strategy in the side of the PWM rectifier, and derive the expression of active power and reactive power. Analyze the double loop structure of rectifier. Explain how to design the regulator of the control system, how to determine the parameters of the main circuit. Simulate the double-loop PWM rectifier and get the conclusion.Decouple the active and reactive power of the stator side based on the method of stator flux-oriented. Derive the expression between rotor voltage and stator current by means of the coupling of stator flux and rotor flux. Build the system block diagram of wind power generation. Analyze the control strategy and explain how to adjust the rotor voltage to follow the optimal power of wind turbine. Figure 86 table 2 reference 56...