A fuzzy logic- based algorithm for discrimination of damaged line during intermittent earth faults

In the paper, the intermittent earth faults and their detection have been discussed. The intermittent fault belong to the most difficult detectable one due to its low and unstable measuring signals. The discussion has been carried out on the true fault recorded in the typical MV distribution network. It is shown that the criterion values applied, up to now, to the ground-fault protections can be ineffective. Therefore, two versions of an original measuring-decisive algorithm based on fuzzy logic have been proposed. With the algorithm, the fault´s detection referring to both the knowledge base and the member grade can be carried out.