Research On Real-time Simulation Technology For Modular Multilevel Converter Based On FPGA

Real time simulation has been an important tool for research on index design,performance analysis and comprehensive evaluation of Modular Multilevel Converter.With the development of electronic devices,MMC real time simulation has set higher demands for high-speed,accuracy,and flexibility.Common modeling methods are not able to keep calculation accuracy and simulation rate in balance,meanwhile,parallelism of main simulation system is limited,which makes it hard to meet the real-time requirement.To solve the problems above,an FPGA-based MMC real time simulation platform is proposed in this paper,which implements a research on the rapid realization method and algorisms of modeling,and main works are listed below:1.Research on designment of rapid realization method for MMC.To solve the problems of the difficulty of the solver development and lack of versatility,the development process is improved in this paper.The rapid realization method adopts parallel designment to shorten the time from concept development to hardware implementation while insuring uniformity of model and VHDL code,which significantly reduces development difficulties of MMC solver.2.Research on modeling algorithm of MMC bridge arm based on backward Euler method.To solve the problem of low simulation rate and large computation load,the method in this paper adopts backward Euler method to discretize inductance of bridge arms and capacitance of submodules,as well as Thevenin’s theorem to achieve equivalent bridge circuit,by which certain arms could be replaced and resolved.The algorithm can precisely simulate charge and discharge process of every submodule,which simplifies the complexity of calculation and increases simulation rate vastly.3.Real time simulation test of MMC is achieved.To solve the problem that accuracy and rate could not be balanced during MMC electromagnetic transient simulation,an MMC simulation model is set up according to rapid realization method,which compares phase A voltage,line AB voltage and upper arm current of phase A of primary simulation to those of hybrid simulation,with 1?s simulation step size.Meanwhile,bridge arm models are resolved on FGPA board,after which modulating wave files are generated by Matlab.The files are downloaded to FPGA and conducted highspeed resolver simulation at 100 ns.The result shows that the model built by rapid realization method can precisely simulate the complete operational status of MMC,with error kept within 0.5%,which verifies the reliability and effectiveness of the method.