Fast electro-magnetic transient simulation method for modular multilevel converter

The commutation process of VSC(Voltage Source Converter) is analyzed and its simplified circuit model is derived,which is effective when the complementary switching mode of its upper and lower legs is adopted in system simulation.As the branch number of simplified circuit model is reduced and its branch equation is simplified,its fast electro-magnetic transient simulation needs less computation time,though the switching dead zone and the converter BLOCK-state could not be simulated.The performance of fast electro-magnetic transient simulation is evaluated through three cases simulated with PSCAD/EMTD,and results show that,the computation time is effectively shortened for MMC(Modular Multilevel Converter) with multiple(more than two) levels.