Permanent Fault Location for Three-Core Cable Using Multiconductor Coupling Model

Phase-to-ground faults in underground cables are usually correlated with the metallic sheaths. This work proposes a fault location method for the three-core cable in distribution system using voltage and current measurements at the both terminals. First, a generic model for the three-core cable with independent sheath is constructed by lumped parameter approach. Then, considering the practical measurement restrictions, a simplified yet effective equivalent circuit is proposed on the basis of the generic model. Additionally, the analysis of the earthed strap current is presented. The earthed strap current is used to determine cable fault distance by voltage and current equations. By PSCAD/EMTDC, an effectiveness evaluation of the proposed model is given, and the performance of the proposed algorithm is investigated with extensive fault simulations. The results demonstrate the method is not affected by different fault conditions. Finally, the comparison with other algorithms shows higher accuracy and feasibility of the proposed method for a three-core cable with independent sheath.