Novel blocking based protection for 220 kV closed-loop underground cable using moving window averaging directional relay

Abstract

A paradigm shift in the philosophy of protection occurs due to distributed generation presence. To adopt the renewable energy generation and enhance supply reliability, a closed-loop operation mode has been involved. The conventional protection cannot adopt the distributed generation since faults have become bidirectional. This paper introduces an ultra-high-speed blocking based on pilot protection system for closed-loop underground cable networks. The proposed protection system uses directional relays based on a suggested averaging window technique and remote terminal units, RTUs, in the automation system. Selection and isolation of the fault zone can be obtained by the neighboring RTUs collaboration. RTUs can automatically be synchronized after fault triggering and don’t require further synchronization process. The executed protection system has been checked for all fault types taking into account fault resistance, load switching conditions, and the effect of charging currents via using the ATP and MATLAB programs. The results confirmed that the recommended protection has several advantages: high sensitivity, ultra-high speed, and selectivity; it has been influenced by neither fault resistance nor the un-faulted areas. It has also proved successful for both operation modes (i.e. open loop and closed loop). Moreover, in such protection, all loads don’t suffer from supply loss save for loads connected to a faulty busbar, and it is, accordingly, immune to load influence.