Impact on superconducting fault current limiters on circuit breaker capability

There has been significant capacity addition to the power system leading to increased fault current at substations buses. This call for costly equipment upgrades and replacements. In order to defer investments utilities are exploring use of superconducting fault current limiters (SCFCL) and current limiting reactors (CLR). The SCFCL can be built with either resistive or inductive shunts. Also, it might be possible to include a recovery switch in series with the superconducting element. The choice of shunt is likely to have significant impact on the current limiting capability of the SCFCL. Also, for correct application design the circuit breaker transient recovery voltage (TRV) should be within its capability limits. It is expected that the TRV will be impacted by the choice of shunt and use of the recovery switch. The paper analyzes the effect of type of shunt on efficacy of limiting fault current and impact on TRV using EMTP-ATP. It is observed that the use of resistive shunt may be better for limiting first peak of the current and limiting TRV values. The inductive shunt reduces the steady state fault current effectively. The use of recovery device has adverse impact on the TRV characteristics of the system.