Simulator study on line fault clearing by DC circuit breakers in a meshed MTDC system

HVDC multiterminal power systems, here referred to as MTDC systems, request increasing interest after the first schemes of this kind are in operation or under commissioning, respectively. A variety of system configurations can be defined whose properties concerning flexibility, reliability and economics are significantly different. Amongst them the meshed MTDC system offers the important advantage that an outage of a line section-even a permanent one-does not prevent the desired energy transfer amongst all of the terminal stations. It is an unavoidable consequence of a DC side fault that the energy transfer in the affected pole of the entire MTDC system is interrupted until fault clearing. Fast fault clearing is therefore an essential requirement in MTDC systems. The authors detail how, DC breakers can render valuable services to fulfil this requirement