Methods for earth fault identification and distance estimation in a compensated medium voltage distribution network

This paper introduces methods for the indication and location of earth faults in a compensated medium voltage distribution network. Algorithms for determining the total phase-to-earth admittance and unbalance of the medium voltage distribution system and each of its MV feeders are presented. Information on earth fault distance can be obtained by rearranging the faulted feeder, normally operated radially, into a closed ring over some healthy feeder. The fault distance along both feeders can be determined by using two different values of the zero sequence voltage and corresponding zero sequence currents of the feeders. Two other methods based on reactive and active components of zero sequence currents can also be used. All the methods presented usually require a compensation of earth fault current. Both fault location and determination of these previously mentioned parameters have been tested in the real compensated MV distribution system.