Current Limiting Hybrid DC Circuit Breaker Based on Capacitor Commutation

DC circuit breaker is an important device for the DC power grid fault removal. In order to improve the reliability of the DC grid operation under a DC fault, a capacitor commutation (Current-limited hybrid DC circuit breaker (CC-CL-DCCB) topology based on capacitor commutation is proposed in view of the high requirements of the breaker’s breaking capacity and its high cost, weak current limiting capacity, slow fault isolation speed and other problems. Having the normal and the fault operating modes, the proposed scheme relies on the comprehensive current limiting of the capacitor reverse charging and the resistive inductive current limiting branch, effectively suppressing the rise of the fault current and reducing the fault current to 3.71kA when the tripping occurs. In addition, it is able to reclose after the fault clearance. It has the diode set which may cause a short circuit for the inductor and a natural discharge for the capacitor, which effectively reduces 1.6 ms in the fault isolation time and 18.44MJ in the energy absorbed by the arrester. The principle analysis and theoretical derivation of the proposed circuit breaker and the simulation analysis in PSCAD/EMTDC show that the proposed circuit breaker topology is applied to the four-terminal DC power grid. Compared with the existing DC fault protection schemes, the proposed circuit breaker has a certain advantages and feasibility. © 2023 Power System Technology Press. All rights reserved.