Fault Characteristic Analysis and Simulation of Power Electronic Transformer Based on MMC in Distribution Network

The topology structures of input stage, isolation stage and output stage of power electronic transformer in distribution network were introduced. Using the type of half bridge modular multilevel converter sub module, the dual active bridge and three-phase inverter as the research object, the simulation model of 10kV distribution network power electronic transformer was built based on PSCAD simulation platform. The theoretical analysis and simulation verification of the possible fault types in power electronic transformer were carried out, including AC input side faults, MV DC side faults, LV DC side faults and power switch component faults, etc. The overvoltage and overcurrent levels of power electronic transformer under various faults were classified and tallied. The fault types which have greater impact on power electronic transformer in distribution network were pointed out.