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.