Hybrid sub-module MMC converter with direct-current fault ride-through capability

The invention relates to a hybrid sub-module MMC (multimedia card) converter with direct-current fault ride-through capability. The hybrid sub-module MMC is similar to the half-bridge MMC in topology, namely a three-phase six-bridge structure, but the single bridge is successively cascaded by m half-bridge sub-modules (HBSM), n full-bridge sub-modules (FBSM) and one clamp dual sub-module (CDSM); the high direct-current voltage utilization rate of FBSM, the direct-current fault current self-cleaning of FBSM and CDSM and the economic advantage of HBSM are integrated to optimally select the amount of m, n and one according to the actual demand, so that the converter can be applied to a flexible direct-current transmission system, in particular, to an occasion with the higher commissioning rate, when the system has one direct-current fault, it is promoted in capacity to save the economic cost under existence of the direct-current fault ride-through capability.