Bridge-Type Hybrid HVDC Circuit Breaker with Reduced Semiconductor Devices

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), sets of low-voltage commutation circuit, low-voltage mechanical circuit breaker (MCB) and high-voltage disconnector (DS) mainly. Each set composes a single arm in a multi-line full-bridge circuit, and the combination of on-off states of all arms offers flexible and bidirectional current interruption 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. High-voltage SCBs installed into all the DC lines are consolidated into a single SCB and high-voltage blocking diodes can be replaced by the DSs in comparison to the conventional hybrid HVDC CBs. A low-voltage scaled-down prototype of the bridge-type hybrid HVDC CB has been fabricated. Fundamental commutation sequences to interrupt ground faults under forward / reverse flow conditions and a DC bus line fault have been successfully demonstrated under 120V, 15A operation.