Resistive Superconducting Fault Current Limiter - Integrated Bidirectional Hybrid DC Circuit Breaker for HVDC Systems

This paper proposes a coupled inductor based bidirectional direct current hybrid circuit breaker (BDC-HCB) integrated with a resistive superconducting fault current limiter (R-SFCL) for fault interruption in high voltage direct current (HVDC) transmission systems. The proposed breaker topology uses an auxiliary resonant circuit for injecting counter-current to the fault current, thereby reducing the fault level in the system to zero. The BDC-HCB topology does not require additional pre-charging circuit for the capacitor and utilizes a soft-switched resonant charging process using thyristors and diodes. The integration of R-SFCL in cascade with the main breaker is shown to significantly reduce the current rating, energy dissipation and fault clearance time of the breaker. The comparison of the maximum fault level in the system with and without the incorporation of R-SFCL is also performed. Finally, the impact of various settings of R-SFCL on the reduction in breaker ratings is also analyzed in this paper. Operation of the proposed topology is validated using detailed controller hardware-in-the-loop results.