Coordinated control of DC circuit breakers in multilink HVDC grid

Abstract

High voltage DC grid is developing towards more terminals and larger transmission capacity, thus the requirements for DC circuit breakers (DCCB) will rise. The conventional methods only use the faulty line DCCB to withstand the fault stress, while this paper presents a coordination method of multiple DCCBs to protect the system. As many adjacent DCCBs are tripped to interrupt the fault current, the fault energy is shared, and the requirement for the faulty line DCCB is reduced. Moreover, the adjacent DCCBs are actively controlled to help system recovery. The primary protection, backup protection, and reclosing logic of multiple DCCB are studied. Simulation confirms that the proposed control reduces the energy dissipation requirement of faulty line DCCB by around 30–42 %, the required current rating for IGBTs is reduced, and the system recovery time reduced by 20–40 ms.