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Protection Configuration and Scheme for the Transmission Line of VSC-HVDC Grid

Voltage-sourced converter(VSC) based high voltage direct current(HVDC) grid can absorb large-scale renewable energy flexibly. But because of its small inertia, a fault in the VSC-HVDC grid will spread rapidly and fault current will increase quickly. Because it is hard for DC circuit breakers to cut off large current, the DC transmission line protection has to operate extremely fast after a fault occurs in order that DC circuit breaker can cut off the fault current before it is too large. This paper discusses the structure and configuration of the DC transmission line protection for VSC-HVDC grid. The existing DC transmission line protection are discussed, and the problems and challenges that DC transmission line protection faces are pointed out.