Dual-circuit hybrid circuit breaker

A DC fault will propagate quickly in a DC grid and results in significant DC voltage drop and large current increase. To protect the DC grid from the DC faults, the concept of hybrid HVDC circuit breaker (DCCB) is widely-accepted due to its low conducting loss and fast operation speed. The unidirectional DCCB recently is considered to fulfil the protection criteria. However, for a well-built DC grid, a massive number of unidirectional DCCB will be applied. This will lead to the high capital cost. For a terminal applied multiple unidirectional DCCBs, their MOVs could be shared to reduce their capital cost. The dual-circuit DCCB is proposed to reduce the size of MOVs by 50% based on the idea of sharing MOV. And the performance of the DC fault blocking is maintained. The structure and operation principle of the dual-circuit DCCB are introduced. Comparing with the unidirectional DCCB, the fault blocking capability and the economy of the dual-circuit DCCB is verified