Power balancing in multi-converter systems composed of modular multilevel converters (MMCs)

Multi-converter systems composed of series or parallel connected modular multilevel converters (MMCs) require a means to manage power sharing between the MMCs by balancing the load during operation. Series connected MMCs require proper voltage balancing while parallel connected MMCs require proper current balancing. The paper describes this imbalance phenomenon, illustrates the solution via simulation results, and presents field measurements obtained with a megawatt class medium voltage DC test facility.