A Review on DC Fault Current Blocking Capability of Modular Multilevel Converter

The high voltage dc transmission system is a mature philosophy for transmission of power over long distance. However, rapid development of modular multilevel converter technology and its acceptance in HVDC systems coupled with immature growth of research on dc circuit breaker have created a challenge for the HVDC systems to face consequences against the occurrence of dc link faults. In particular, this de fault blocking capability depends on proper choice of the submodule, which in turn is based on the optimum decision regarding cost, fault clearing time and degree of reliability. Therefore, the purpose of this review paper is to present the current status of the fault protection features of modular multi-level inverters and to provide a clearer picture of the present mechanisms of blocking the dc fault current.