Resonant DC circuit breaker in MMC-HVDC transmission system

Abstract

Recently, high-voltage direct current transmission system (HVDC) which can achieve large-scale system has attracted attention with increasing amount of renewable energy. In addition, it is necessary to use large capacity converter for bulk power transmission. Therefore, modular multi-level converter (MMC) is optimum as a large capacity converter. MMC composed of chopper cell is lower cost and loss than full bridge cell topology. However, chopper cell MMC doesn't have blocking function, so it is not possible to cut off the fault of the DC side. Furthermore, the blocking of DC fault is difficult because the DC systems cannot generate current zero-cross point such as AC system. The proposed circuit breaker can eliminate the fault of the DC side. This breaker generates a current zero-cross point by using the resonance current, generated by the LC circuit. In this paper, characteristic of the proposed circuit breaker is verified by simulations.