A Fast Resistive SFCL Based Suppression Strategy for Turn-to-Turn Faults in a Converter Transformer

A succession of converter transformer rupture and explosion accidents originating from internal short-circuit faults have aroused wide concern. In these cases, limited by the inherent time delay of protection and the tripping time of circuit breakers, the equipment continuously suffers from overpressure induced by a large amount of arcing fault energy. To address this problem, a fast suppression strategy for converter transformer turn-to-turn faults is established by using a resistive superconducting fault current limiter (R-SFCL). Through the proposed coordination with relay protections, the R-SFCL will be rapidly deployed after the occurrence of a fault. The simulation results reveal that both the fault arc current and the released energy can be significantly limited by the quenching process of the R-SFCLs. Specifically, the proposed suppression strategy reduces the fault arc current and released energy by 28.3% and 24.6%, respectively, under a severe turn-to-turn fault shorting 50% of windings. In addition, the proposed suppression strategy is validated to be more effective in dealing with more severe faults.