Utilisation of symmetrical components in a communication‐based protection for loop MV feeders with variable short‐circuit power

Variability of the available short‐circuit power also implies variation of the fault level, which can potentially cause several protection problems in the electric networks. In this study, a novel protection method that is insensitive to the fault level changes caused by variable short‐circuit power is presented. It relies on utilisation of symmetrical components of the short‐circuit currents and on communication between the protection relays. The proposed method addresses the single phase to ground (SPG) faults occurring in directly grounded distribution networks, with focus on closed‐loop medium voltage (MV) feeders. Case studies are presented, which demonstrate that the proposed protection scheme is capable of effectively detecting the SPG faults in closed‐loop feeders with variable short‐circuit power.