Coordinated Application of Flux-Coupling SFCLs and Passive Mechanical DC Circuit Breakers for Enhanced HVDC Fault Protection

Interrupting current in high-voltage direct current (HVDC) networks is one of the most challenging protection issues in modern DC systems, due to the absence of a natural zero-crossing and the extremely rapid rise of fault current (di/dt). Limiting the fault current magnitude, providing an appropriate commutation path, and safely absorbing fault energy are among the most demanding requirements in the design of DC circuit breakers (DCCBs). One effective approach to mitigate these stresses is the synergistic integration of flux-coupling superconducting fault current limiters (FC-SFCLs) with passive mechanical circuit breakers (P-MCBs). This paper investigates a modified flux-coupling-type SFCL (FC-SFCL) and evaluates its effectiveness in the successful operation of passive mechanical circuit breakers (P-MCBs) in HVDC systems. The approach combines the advantages of resistive SFCLs (fault current magnitude reduction) and inductive SFCLs (slowing the di/dt) simultaneously. First, the operating principles of the FC-SFCL and P-MCB are examined, and then the impact of the FC-SFCL is analyzed through simulations under two fault scenarios: close and distant from the P-MCB. Simulation results show that an appropriately designed FC-SFCL can reduce the peak fault current by about ۳۷% under far-end faults and up to ۸۰% under near-end faults, resulting in a significant reduction in the required commutation capacitance and enhanced interruption performance. The integration of this SFCL with P-MCBs can provide a promising pathway for developing fast, low-stress, and reliable protection solutions in future HVDC networks.

کلیدواژه ها:

HVDC systems ، DC circuit breaker (DCCB) ، Superconducting fault current limiter (SFCL) ، Flux-coupling SFCL (FC-SFCL) ، Passive mechanical circuit breaker (P-MCB)