Design and Analysis of Multi-pole MMC-HVDC

Modular multilevel converter (MMC) is replacing all existing voltage source converters (VSCs) in various applications. Muti-pole high voltage DC (HVDC) is one among the few applications, still unexplored significantly. The present paper tries to bridge that gap. Three-wire symmetrical and asymmetrical MMC-HVDC configurations using two MMCs are proposed. Performance analysis has been carried out with both MMCs operating under identical as well as different settings. An analysis to ascertain the impact on one MMC following the changes in operating conditions of other MMC has been carried out. The present work focuses on the three-wire structure as a three-wire structure can be used to upgrade existing AC transmission lines into an HVDC transmission line. The proposed study has been carried out using the electromagnetic transient (EMT) model of MMC on the real-time digital simulator (RTDS).