Research On Control Strategy Of Co-phase Power Supply Converter Based On MMC

The power quality problems and electric separation in the existing lines seriously restrict the security and stability of traction power supply system.The co-phase power supply technology solves above problems.While the single phase combined co-phase power supply system was further improved,which has better economic and technical capability.By applying the modular multilevel converter(MMC)to the single-phase combined co-phase power supply system can exert the advantages of MMC in high voltage and high power applications,at the same time,it can save cost by saving the traction transformer.In this paper,the research object is single phase combined co-phase power supply system based on MMC,emphatically the control strategy of co-phase power supply converter based on MMC.The main work of this paper is as follow:(1)To analyze the principle of MMC sub module and to establish mathematical model of the co-phase MMC.On the basis of this,to compare the topology structure of different number of arms of the co-phase compensation device.In different ways such as control strategy,bridge arm current and sub module voltage.(2)To research the generate mechanism of circulation and to perform a quantitative calculation.The simulation of circulation suppression strategy based on PR regulator based on MARLAB/Simulink is also been designed to simulate the circulation suppression in single phase MMC in inverter condition.(3)To compare the applicable of different modulation mode and to choose the suitable carrier phase shift modulation method for topology structures in this paper.To analyze the pre-charge control method of MMC sub module and the equalization and regulation control method of the voltage on the capacitors of the sub module,and to verify this in the simulation in MATLAB/Simulink.Finally,the control strategy of co-phase power supply converter is given.(4)After calculating the parameters of main circuit,to establish the simulation model of locomotive traction,regenerative braking and load mutations of the AC-DC-AC type locomotive and traction conditions of the AC-DC type locomotive,which is based on the MATLAB/Simulink.And to verify the effectiveness of the topology structure of the MMC co-phase power supply converter and its control strategy designed in this paper.