Over current protection coordination of distribution networks with fault current limiters

The connection of new distributed generator (DG) to the existing network increases the fault current and disturbs the existing over current (O/C) protection coordination. The main focus of this study was to investigate the possibility of using a fault current limiter (FCL) to address the above issues. A case study was carried out for a 20 kV distribution network in interactive power system analysis (IPSA) simulation package. Connection of a DG to the considered network increases the fault current closer to the rating of two switchgears and disturbs the O/C protection coordination. An FCL is introduced and varies its impedance and location of installation to investigate the limiting capability and effect on protection coordination. The modifications required to O/C protection scheme for proper coordination were also investigated. The study proved that when locating the FCL near the DG, it limits the fault current while minimizing the problems associated with the protection