Application of Active Superconducting Fault Current Limiter in Nine Bus Ring System and its Impact on Distance Protection

Abstract

With the increasing load demand and interconnection of distributed generations, there has been a significant rise in short circuit levels in transmission as well as in distribution networks. The increment in fault current has imposed burden on the existing system equipments and also cause system instability. The application of Fault Current Limiter (FCL) has helped to overcome these problems. Active Superconducting FCL (ASFCL) and Resistive Superconducting FCL (RSFCL) have been compared in nine bus ring system with SFCL placed near all three sources using Matlab/Simulink. Different types of faults have been simulated at various locations of the transmission lines in the bus system under consideration. The effect in the magnitude of fault current and voltage profile on the swing bus with inclusion of SFCL for line to ground fault has been compared for both the types of fault current limiters. The percentage reduction in the current magnitude of the faulty phase after fault inception has been observed to be more in ASFCL compared to RSFCL along with the improvement in the voltage profile. Furthermore, the inclusion of ASFCL impact on the distance protection scheme of the transmission line has been scrutinized. Considerable change in the reactance as seen by the distance relays has been observed due to superconducting air core transformer used in ASFCL while there is negligible change in the resistance. The effect on overcurrent protection used as back up protection has also been analysed due to reduction in the amplitude of the fault current.