Research on DC Fault Ride Through of Medium-Low Voltage DC Distribution Network Based on Hybrid MMC

摘要

In order to interrupt and clear fault current when a short circuit fault occurs on the DC side of the medium-low voltage DC (MLVDC) distribution network, a hybrid modular multilevel converter (MMC) topology with the ability of DC fault ride through is proposed. This topology consists of half-bridge submodules (HBSMs) and clamp single submodules (CSSMs). Hybrid MMC is an economical topology which can reduce the number of power devices and power losses. The equivalent circuit of hybrid MMC before and after a bipolar short circuit fault is established and the quantitative relationship between CSSMs and HBSMs is deduced in this paper. Finally, a simulation model is established in PSCAD/EMTDC software and the simulation results verify the effectiveness and feasibility of hybrid MMC.