Small Signal Modeling and Analysis of Open-loop Response Time Constant of MMC

It is very hard to analyze the relationship between dynamic response and main circuit parameters of modular multi-level converter(MMC),because its AC and DC voltage is established by distributed sub-module capacitances.For providing basis for the design of the MMC controller,this paper presented the modeling method for MMC’s state space equation and open-loop transfer function from state variables to control variables,and presented the controlled source decoupled model of average sub-module in the rotating coordinate system.Based on the systematic research and experience in developing the 49-level MMC-HVDC dynamic simulator,comparison result shows that the modeling process is valid and could be used in design of a closed-loop controller for actual MMC-HVDC project.