A Snubberless Hybrid Circuit Breaker for Medium Voltage DC grids

This paper presents a hybrid circuit breaker (HCB) which is suitable for fast fault interruption in medium voltage dc (MVDC) systems. Proposed topology employs an actively switched capacitor branch in parallel with the main conduction branch to facilitate fast current commutation during a fault. The mechanical breaker in the main branch is turned off at zero current. This eliminates arc formation across the moving contacts of the breaker. Moreover, the fault interruption process does not require a varistor for network demagnetization following the fault current commutation. This paper also presents a discharging mechanism for the capacitor in a practical implementation. Performance of the proposed dc circuit breaker is evaluated through exhaustive simulation results.