Research on a novel bidirectional direct current circuit breaker

A novel Medium Voltage Direct Current (MVDC) circuit breaker consisting of a High-Speed Switch(HSS) and a bridge-type commutation branch, which is based on current injection, is proposed and analyzed in this paper. The commutation branch of this design adopts bridge type, which can break bidirectional fault current rapidly by controlling thyristors. Meanwhile, after fault current is commutated to the commutation branch completely, the freewheeling diodes can provide time for dielectric recovery with zero recovery voltage across HSS, which can improve the reliability of fault current breaking. The principle and operation sequence of this topology are described. Based on the simulation model, the breaking process in 10kV DC system with different fault current rates of rise are simulated. Besides, the relationship between the current commutation capability and the loop inductance is investigated. Finally, the prototype of 10kV DC circuit breaker is constructed, and the fault current breaking tests are carried out with breaking current of 20kA and above, which validate the feasibility and effectiveness of the topology and simulation model well.