We propose a bridge-type hybrid high-voltage direct-current (HVDC) circuit breaker (CB). The proposed hybrid HVDC CB consists of a single high-voltage solid-state circuit breaker (SCB), a set of low-voltage commutation circuits, low-voltage mechanical circuit breakers (MCBs) and high-voltage disconnectors (DSs) mainly. Each set composes a single arm in a multi-line full-bridge circuit, which offers flexible and bidirectional current paths under various fault operation conditions. One of the most significant features of the proposed hybrid HVDC CB is the utilization of small number of high-voltage semiconductor power devices. Single SCB is utilized for multiple DC lines and high voltage blocking diodes in the conventional hybrid HVDC CBs can be replaced by the DSs. A low-voltage scaled-down prototype of the bridge-type hybrid HVDC CB has been fabricated, and a fundamental commutation sequence to clear a grounding fault current has been successfully demonstrated under 120V, 15A operation.
