The Research Of Simulation And Experiment On Operation And Control Characteristics Of Variable-Speed Constant- Frequency Doubly-Fed Wind Power Generator

Wind power generation has been developing quickly in resent years.Now many kinds of technologies applied to wind power generation are in the ascendant,among which the technology of variable speed and constant frequency(VSCF) is getting increasing recognition for its characteristic of high-efficiency and practicability. On the base of the traditional technologies of wind power generation and the relative technique research,the technical approach of VSCF wind power generation using A.C excited doubly-fed induction generator(DFIG) was comprehensively investigated from theory to practice, from simulation to experiment. The main contents of the thesis are as follows:First, this thesis analyzes DFIG operation theory, including mathematic model of DFIG coordinate transformation, DFIG operation characteristics, DFIG power relationship, which establishes the theoretical foundation for succeeding study.The second,on the part of taking control strategy,in order to realize decoupled control of DFIG active and reactive power , field oriented vector control technique was applied to DFIG control, A general control strategy based on stator flux oriented vector control was proposed as well.The third,on the base of analyzing the demand of vector excited converter of DFIG which is operating on the state of VSCF, the thesis discusses the structure, characteristics,modulation method of PWM converter,using the modulation method of Space Vector Pulse Width Modulation(SVPWM).At last, in order to testify the validity of the basic theory and the control strategy proposed by the antecedent part, a series of research of simulation and experiment have been carried out on AC excited VSCF wind power generation system.A simulation platform of AC excited VSCF wind power generation system was founded including wind turbine model,DFIG model and control model which including SVPWM modulation signal model,PWM converter model and current closed-cycle control system whose control object is rotor current by Matlab/Simulink.Through above work ,the simulation has achieved the purpose that DFIG can operate on the state of VSCF which is based on the stator flux oriented vector control strategy.In the simulation, both the output power and power factor also can be controlled validitily by adjusting the rotor current which makes the control more simply. The analysis of the simulation results shows that the double-fed VSCF wind turbine generator has a good dynamic characteristic by the vector control.In the experiment, a small capacity experimental laboratory model machine system has been constructed and a series of experimental study including the experiment of single machine constant frequency constant voltage,the experiment of connecting to grid conditions which is separately excitation and the experiment of self-shunt excitation which is on the condition of no load has been done. The result of the simulation and experiment all validated the validity and feasibility of theoretical model and control strategy.But because of the complexity and the integrity of the subject,which determines its difficulty is very great,some difficulties and emphasis are still required to research and perfect further more.