A New DC Fault Blocking Capability Technique for Modular Multilevel Converters

In this paper, a new structure to block DC-link short circuit fault current in modular multilevel converters is proposed. The proposed structure is based on using an extended 3-level Neutral point clamp converter in the output terminal of the MMC, which makes the modular multilevel convert able to block the current path in the faulty condition and protect the semiconductor switches in the event of fault. Moreover, the proposed structure is able to increase the number of voltage levels in the output while reducing the number of power switches and floating capacitors. The proposed technique is simulated in MATLAB simulink and the effectiveness of the proposed structure is verified.