Universal Equivalent Model of Hybrid DC Circuit Breakers for Electromagnetic Transient Research

As critical protection devices in DC grids, DC circuit breakers can cause overlapping grid fault characteristics, fundamentally altering system electromagnetic transient behavior. This paper analyzed the interruption process of hybrid DC circuit breakers (HDCCBs) with different topologies, elucidating the fundamental mechanisms of HDCCB interruption. The essential interruption characteristics of HDCCBs were investigated through comprehensive analysis of multiple topologies, with key parameters identified and an detailed model incorporating stray inductance effects developed. A universal equivalent electromagnetic transient model was established to characterize breaker performance, which is suitable for electromagnetic transient research. Verification was performed in a four-terminal MMC-HVDC grid based on the PSCAD/EMTDC platform, demonstrating effective fault clearance with the voltage peak error of universal circuit breakers not exceeding 5%, while addressing the critical challenge of overlapping fault characteristics that fundamentally alter system electromagnetic transient behavior.