Research On Wind Power Converters For Flexible DC Transmission

With the rapid development of the domestic economy,the consumption of fossil fuels such as oil,natural gas and coal is increasing.Therefore,the environment is polluted seriously.For example,the haze problem is getting worse.With the development and utilization of wind power and other renewable clean energy sources,wind power generation technology has received more and more attention.Due to the wide application of doubly fed induction generator(DFIG),the control technology for DFIG has become increasingly mature.However,the control technology applied to DC converter system for DFIG still needs to be study.Based on the new topology of doubly fed induction generator,this paper studies the application of PI control strategy,model predictive control strategy(MPC)and input-output feedback linearization control strategy(IOFL)in this topology based on the mathematical model of the system.First of all,the research background and significance of this topic are introduced,and the research status of stator side converter(SSC)and rotor side converter(RSC)topology of DFIG is introduced.The relevant control strategy for DFIG converter is briefly described.The main contents of this paper are introduced.Secondly,the working principle of the traditional DFIG and it's mathematical model in the ABC three-phase coordinate system are elaborated introduced.By using the CLARK and PARK coordinate transformation methods,the DFIG mathematical model in dq rotating coordinate system is deduced.The mathematical model and the basic working principle of the SSC and RSC under the new topology are introduced.Thirdly,based on the new topology mathematical model of the DFIG,the PI control strategy and model predictive control strategy applied to converter are studied.The input-output feedback linearization strategy is also applied to the converter.At the same time,corresponding MATLAB simulation models are built respectively.Based on the above three control strategies.The simulation results are analyzed and the feasibility of the control strategy is verified.Finally,the hardware platform and software of DFIG are designed.The hardware Platform of DFIG is build.At the same time,related experiments are carried out.Among them,the hardware design includes a primary circuit design and a secondary circuit design of the SSC and SSC.the software design includes wind simulationprogram design and converter control program design.The idea of variable frequency of DFIG under the variable speed is verified by experiments.the RSC can realize the speed tracking and the SSC control the stator voltage steadily.