Principle Analysis and Parameter Design of Resonant-Current-Assisted Arcless Soft Switching DC Circuit Breaker

The DC circuit breaker is a crucial component in the DC power grid as it effectively limits and swiftly clears faults in DC transmission lines. However, existing medium and high voltage DC circuit breakers face challenges such as limited breaking times and high stress on devices due to contact ablation. To address these issues, this paper proposes a resonant-current-assisted arcless soft switching DC circuit breaker (RASS-DCCB). The RASS-DCCB utilizes controlled oscillation to facilitate fault current commutation, ensuring reliable switching. This approach enables arcless switching of the disconnector and soft switching of semiconductor devices. The working principle, fault handling process, and transient stress of key components in the RASS-DCCB are theoretically analyzed. Moreover, suitable parameters for the core components are designed and provided. A simulation and analysis of the technical performance of a standard 20kV/10kA/3ms RASS-DCCB are conducted. The results demonstrate that the proposed topology can bidirectionally clear fault currents within 2.65ms. The IGBT is switched off at zero current, resulting in zero transient voltage stress throughout the entire switching off process, thereby enhancing reliability. The feasibility and advantages of the proposed topology are comprehensively demonstrated.