Operational improvement of Modular Multilevel Converter with redundancy sub-modules by new NLC Scheme

This paper proposes an operational improvement of MMC (Modular Multilevel Converter) with redundancy SMs (sub-modules) by a new scheme of NLC (Nearest Level Control), which can offer reduction of voltage harmonics and switching loss. The feasibility of proposed scheme was verified through computer simulations with PSCAD/EMTDC software. Based on simulation results, a hardware prototype of 10kVA, DC-1000V MMC was designed and manufactured in the lab. Various experiments were conducted to verify the feasibility of proposed scheme in the actual hardware environment. The developed prototype can be effectively utilized for analyzing the performance of MMC according to the various modulation schemes.