Design and performance of a capacitor commutated DC circuit breaker

Hybrid high voltage direct current circuit breakers (DCCBs) are capable of interrupting a fault current within a few milliseconds, but this technology suffers from high capital costs, especially in a meshed HVDC grid. To increase the economic competitiveness of hybrid DCCBs, this paper proposes a capacitor commutated DC circuit breaker (CCCB). The CCCB mainly comprises an auxiliary branch with a fast disconnector in series with semiconductor devices and a main branch with series connection of a DC capacitor and diode valves. This paper provides a detailed depiction of the CCCB. The topology and operating principles are discussed. The general sizing method for the main components in the CCCB is detailed. Furthermore, several extended topologies are proposed to further reduce the semiconductor cost and on-state operation power loss. Extensive simulations verify the DC fault isolation of the CCCB.