A Detailed Review of MMC Circuit Topologies and Modelling Issues

MMC is a promising technology for MTDC systems and would transform into the concept of Supergrids in the near future. The salient features of MMC are modularity, reduced dv/dt and di/dt stress on switches, voltage and power scalability, inherent fault blocking capacity, transformerless operation, and improved power quality. However, there are some technical issues and challenges to be critically analysed and addressed. There is room for development of novel and enhanced MMC based on SM configurations to enable higher efficiency, improved power quality, compactness, and DC fault blocking capacity. Moreover, development of efficient and accurate models is required for the studies of MTDC grids during steady-state and transient conditions. Literature review suggests a need for studying and comparing different MMC modelling approaches because no modelling technique can be best suited for all applications. The main contribution of this paper is to provide a comprehensive review of recent developments in MMC in terms of SM configurations. This paper also presents an in-depth review of systematic comparison of different models of MMC, which can enable appropriate selection of model based on target studies and desired accuracy and efficiency. Finally, the associated research challenges and future trends are presented.