The Study On PWM Converter Technology For The Double-Fed Induction Generator System

Recently,energy sources increasing continuously and environment empoison being serious gradually,force people to consider new and renewable energy development and utilization.Due to the obvious advantage of wind power,the wind power generation technology has drawn more and more attentions from tremendous scholars.The control of generator excitation,which is the key technology,has became the hot research.The development of domestic and international wind power generation technology is introduced.Several excitation converters used in the doubly-fed wind power generation system are compared.The rotor-side PWM converter function and control method are discussed.After analyzing the operation principle and the mathematical model about Doubly-Fed Induction Generator(DFIG),the dual-closed-loop control system is created.The system is based on stator flux oriented vector control.At the same time,principles and implementation about space vector pulse width modulation(SVPWM) is studied.The Karnaugh map logic function simplification method is used to determine the sector.Several mathematical models of grid-side PWM converter in different coordinate system are analyzed.A voltage-current dual-closed-loop control system of the grid-side PWM converter based on voltage-oriented is designed.It's steady-state power characteristics is analyzed.Then in MATLAB/SIMULINK environment,a doubly-fed generation system simulation model is set up.The simulation is divided into five stages,including DC bus charging stage,the motor start-up phase and the three stages of system operation status.The simulation results show that the system has excellent performance.The results also indicate the grid side converter possesses many advantages,such as high power factor,low harmonic and energy bidirectional flow.The doubly-fed wind power generation system is designed based on DSP.The hardware of the system is designed,including main circuit,signal processing circuit,communications interface circuit,quadrature encoder pulse circuit and protection circuit.The software is also designed,which contains the flow chats of main control procedures and the flow modules.