Basic Theory Research And Simulation Analysis On DFIG Wind Power System

With attachment importance to energy source scarcity and environment pollution the wind electric power generation has developed dramatically all over the world. How to enhance unit capacity and operation effectively and use the wind energy becomes important matter of the wind electric power generation. In various system alternatives, variable speed constant frequency doubly-fed induction generator (DFIG) becomes mainstream for its advantages.First, based on DFIG fundamental equation, the dissertation creates equivalent circuit and internal power relationship, used a 3.5kw 6 poles wound induction generator as example, analyzes generator characteristic with different states, which establishes the theoretical foundation for succeeding study. The second, introduces wind turbine operation theory, according to the wind turbine characteristic, the maxim power capture scheme by the way of DFIG power control was put forward, power system voltage oriented vector control and stator flux oriented vector control is used respectively in the grid side and the rotor side converter, the variable speed constant frequency and decoupling the active and reactive power control are implemented by modulating the rotor current. On the base of traditional vector control, the improving excitation system is established by importing the dynamic change in network voltage and state flux current. The third, based on the analysis of existent techniques of wind generator grid-connection, According to the basic theoretical of electromagnetic, combining the FEM with external circuit, a mathematical model of the double fed induction generator is established in this dissertation, and generator no-load characteristic curve with different speed was calculated. Besides, the performance of double-fed wind generators at different speed and different load is calculated and compared with experimental data.Some benefit conclusion is gained.