Most of existing current protection strategies of flexible DC systems mainly rely on fault identification, and then block the converter through the action of the protection system. In this paper, a novel DC voltage with active current-limiting capability has been proposed for DC fault ride-through (DC-FRT) of full-bridge modular multilevel converter (FB-MMC). With this method, the output of DC voltage control has been directly used as the zero-axis component of final modulation signals of FB-MMC, to control the number of positive or negative insertions of the full-bridge sub-modules (FB-SMs), with the final purpose for current-limiting in DC-FRT. In addition, a simple DC voltage feed-forward control has been adopted to improve DC voltage dynamic, to reduce the peak value of the transient fault current. The PSCAD/EMTDC simulation results show that the proposed control can effectively limit the peak fault current and provide a stable steady-state fault current without relying on fault detection.

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