Capacitor commutation type DC circuit breaker with fault character discrimination capability

Flexible direct current (DC) grids face a serious challenge in terms of rapidly isolating DC faults. A DC circuit breaker is an effective solution for DC fault isolation. To improve the fault-isolation and reclosing capability of flexible DC systems, a new high voltage direct current (HVDC) circuit breaker topology with adaptive reclosing capability is proposed in this paper. The topology of the circuit breaker is a T-shaped structure, which has the ability to break the current in both directions and effectively reduce the cost of components. Meanwhile, after the fault is cleared, the circuit breaker is controlled to inject a voltage signal into the line. Based on this, to prevent the circuit breaker reclosing in the event of a permanent fault from having an impact on the system, a method for fault identification based on Euclidean distance that uses the voltage signal to identify the fault properties is proposed. Finally, the performance of the circuit breaker is simulated and verified by PSCAD/EMTDC simulation software, and compared with the typical existing circuit breakers to verify the effectiveness of the circuit breaker and reclosing scheme.