Interrupting characteristics of the transformer superconducting fault current limiter

This paper analyzed the fault current limiting characteristics of the previously proposed transformer superconducting fault current limiter (TSFCL) interruption system according to its transformer type. The TSFCL interruption system is an interruption technology that combines a TSFCL, which uses a transformer and a superconductor, and a mechanical DC circuit breaker. This technology first limits the fault current using the inductance of the transformer winding and the quench characteristics of the superconductor. The limited fault current is then interrupted by a mechanical DC circuit breaker. The magnitude of the limited fault current can be controlled by the quench resistance of the superconductor in the TSFCL and the turns ratio of the transformer. When the fault current is controlled using a superconductor, additional costs are incurred due to the cooling vessel and the length of the superconductor. When the fault current is controlled using step-up and step-down transformers, however, it is possible to control the fault current more economically than using the superconductor. The TSFCL interruption system was designed using PSCAD/EMTDC-based analysis software, and the fault current limiting characteristics according to the type of the transformer were analyzed. The turns ratios of the step-up and step-down transformers were set to 1:2 and 2:1. The results were compared with those of a transformer with a 1:1 turns ratio