A Novel Hybrid MMC DC Fault Ride-Through Control Strategy Based On Virtual DC Motor

Aim at the lack of dc fault handling capability for modular multilevel converter(MMC), A novel dc fault ride- through (FRT) control strategy based on virtual dc motor (VDCM) for hybrid MMC, whose arm adopts the mixture of full- bridge sub-module (FBSM) and HBSM, is proposed in this paper. This proposed strategy adapts adopts AC and DC independent control which ensures that reactive power and voltage support can be provided for the dc system during dc fault. Besides, the proposed strategy can not only suppress the dc fault current under the pole-to-pole (PTP) fault, enahnces the stability of dc voltage for the dc system to improves the dc voltage stability when the dc grid operates normally by the power feedforward controller. Based on the analysis of the novel FRT strategy, The FRT capability is further optimized, three examples are established in PSCAD / EMTDC to verify its fault handling capability and steady-state anti-disturbance capability.