Sdudy Of Converter Structure And Vector Control For Open Winding Brushless Doubly-fed Wind Power Generator

Variable speed constant frequency (VSCF) brushless doubly-fed wind powergenerator (BDFG) has a broad prospect of development in the field of high power VSCFwind power generation, because the structures like brush and slip ring which are toovulnerable to affect the life of the electric machine, are got rid of. Only fractional ratingconverter is needed, direct driven or half-direct driven operation can be realized, improvingthe reliability of generation system itself, also decreasing the system cost. Taking theNational Natural Science Foundation of China "Open Winding Brushless Doubly-fedGenerator with Composite Rotor and its Direct Power Control Strategy"(Project Grant:No.51277124) as background, a novel open winding brushless doubly-fed wind powergeneration system is studied. Dissertation research mainly covers the following aspects:First, BDFG with special cage rotor, which has been deeply studied at present, isadopted as the research object in this dissertation. Principle of variable speed constantfrequency operation and energy conversion situation are analyzed, and mathematicalmodel respectively in the d-q synchronous reference frame and dual-synchronouscoordinate reference frame.Secondly, whereas the current development trend that wind energy generationsystems are taking the way of large-scale installation and requirement on converter’sproperty is getting higher and higher, a novel BDFG system is proposed, that is to say,open winding structure is applied, and two back-to-back voltage side converters arerespectively connected to both sides of the control winding. Advantages of the new systemcomparing with the previous system are detailed analyzed.Thirdly, as for the new converter structure，a component clamp-compensationSVPWM method using in the machine side converter (MSC) is designed to make sure thatfrequency of control winding’s current can meet the requirement of control system, andvoltage and current double loop SVPWM strategy using in the grid side converter (GSC) isdesigned to achieve the high power factor operation and to keep the voltage of DC bus stable. Furthermore, steady-state simulation models based on MATLAB/SIMULINKsoftware are built to test the feasibility and accuracy of the SVPWM strategy.At last, two different vector control strategies of open winding BDFG are proposed toadapt to two different types of rotor structure of BDFG. And simulation model of openwinding brushless doubly-fed wind power generation system based on theMATLAB/SIMULINK software is established.Simulation results show that controlsystem operates stably, and it can basically meet the operation requirements of VSCF windpower generation.