Coordinated Control Research Of Variable Speed Fixed Frequency Double-Fed Wind Power System

As today's shortage of energy and pollution of environment is very serious, it is meaningful to exploit renewable and clean wind energy. Countries all over the world have been competiting to develop the technology of this field. Among all the technology, variable speed fixed frequency double-fed wind power system is the most widely used, especially to use the wound asynchronised motor as double-fed machine. Baed on this system, we can use AC excitation feququency converter to realize the maximum wind power caputure variable speed fixed frequency wind generation.Compared with traditional current converter, double PWM frequency converter as the core part of the variable speed fixed frequency power generation system has better input and output,low harmonic wave and wide speed regulation range characteristics. The rotor side converter is responsible for the vector control of double-fed machine to capture the maximum wind power based on the given speed and indendently coordinate the reactive power; Grid side converter is responsible for power exchange between rotor side and grid side through DC bus capacitor. To reduce the voltage fluctuate of DC bus, we usual increase the capacity of the capacitor but meaningwhile to amplify the cubage and weight of it as well. That would make the whole system unreliable. To solve this problem, the paper outlines a new coordinate control scheme of double PWM frequency converter.This paper first analyze the speed control theory of double-fed machine and its math model, maximum wind power capture base on given speed and stator flux oriented vector controlism. Through the analysis of double closed loop PI control system about the dismissment of active and reactive power could be established. Then also through the analysis of math model of three phase PWM converter in d,q reference, double closed loop PI control system about stabilization of DC voltage and unit power factor operation could be established. After research the disadvantage of independent control of rotor side and grid side converter, a new load current pre-feed and improved coordinated control strategy is brought forward.Under Matlab/Simulink software surrounding, simulation is made to testify the researched theory such as variable speed fixed frequency maximum wind power capture,speed track and power fluctuate under different operation status. Working is focus on the new coordinated control strategy simulation. The voltage fluctuation of DC bus is less and speed of regulation of it is faster with the same capacitor but different control scheme. When the voltage of grid falls off sunddenly, an improved stator flux oriented control scheme is put forward and simulation is made to testify its correctness.At last, I introduce the dSPACE real time development system used in wind power test platform, including the software and hardware configuration. Grid side conveter is used as example in the paper to be deccribe the development process of how to design the rapid control proptype (RCP) and control the converter. Also the test result and its analysis are given.