On the Correlation between Switching Overvoltages and System Parameters in HVDC-VSC Links Equipped with DC Circuit Breakers

Multi-terminal HVDC systems based on modular multilevel converters in half-bridge configurations are expected to significantly enhance future grid interoperability and stability. However, these systems have no inherent dc short-circuit interruption capability. While HVDC circuit breakers offer a promising solution, their installation requires a thorough evaluation of both switching overvoltages and voltage polarity reversals. In this paper, the main system parameters influencing the generation of switching overvoltages caused by dc circuit breaker operation were analyzed. A detailed parametric analysis was performed, revealing that while reducing the circuit breaker fault clearing time and minimizing the magnitude of overvoltages are conflicting objectives, an optimized design can achieve a careful balance between the rapidity of the protection system and the insulation coordination requirements of the components of the system.