Evaluation of Arm Reliability in Modular Multilevel Converters with Multiple Sub-modules for MVDC Applications

Since the reduced number of sub-modules (SMs) in modular multilevel converters (MMCs) for medium-voltage DC (MVDC) applications cannot provide the same redundant design as high-voltage DC (HVDC) systems, reliability becomes a significant issue in MVDC systems. To evaluate the reliability performance of converters, arm reliability in MMC requires to be analysed and the design of redundancy can be further optimised. Considering the number of redundant SMs, redundancy operation schemes, and correlation coefficient between SMs, arm reliability are analysed in MMC for MVDC systems with multiple SM topologies. The aim of this paper is to provide a comprehensive evaluation of arm reliability in MMC with multiple SMs and identify the high-reliability options for SMs in different scenarios for MVDC applications.