Multi‐Layer MTDC Protection: Design and Simulation Assessment

ABSTRACT With the growing demand for scalable and resilient high‐voltage direct current infrastructure driven by offshore renewables and international power exchange, multi‐terminal DC (MTDC) systems are emerging as a key solution. However, their deployment is hindered by the lack of effective DC fault protection. Conventional single‐layer architectures assign detection, limitation, and interruption to a single breaker, resulting in over‐engineered designs and high system complexity. This study proposes a multi‐layer protection approach that decouples fault current management into two dedicated functions: a thyristor‐based fault current limiter for initial current suppression and an active resonance circuit breaker for selective fault isolation. A comparative simulation using the CIGRE B4.57 MTDC benchmark in PSCAD/EMTDC evaluates the proposed scheme against a widely adopted hybrid DC circuit breaker baseline. The results demonstrate reduced peak fault current, lower surge‐arrester stress, and a significant decrease in semiconductor requirements. Together, these outcomes confirm that the proposed multi‐layer architecture provides comparable interruption performance while offering practical implementation advantages and improved scalability for future MTDC systems.