A Multiport Circuit Breaker-Based Multiterminal DC System Fault Protection

Although hybrid circuit breaker (HCB) uses a combination of mechanical switch and insulated-gate bipolar transistors (IGBTs) to accommodate HVDC application, it still has a large number of series-connected IGBTs in its main breaker. Besides, in multiterminal HVDC system, three or more HCBs appear in cluster at one node, which worsens the HCBs' disadvantage in volume. To simplify the breaker cluster's topology structure and control system as well as increase the compactness, a multiport circuit breaker (MPCB) is proposed in this paper with its control procedure presented. By assembling the HCBs at one node, it can not only cut down the component count for fault interruption remarkably but also reduces the number of control signals. Apart from this, due to a more compact structure, the proposed circuit breaker avoided the use of a dc bus and, hence, dc bus fault which will result in disconnecting the node completely from the system. Hence, regardless of faults and their fault locations, it is always able to connect the remaining healthy ports together. Finally, the effectiveness of the proposed MPCB in different fault scenarios is verified by RTlab.