New ground fault location approach for partially coupled transmission lines

Abstract

The technical requirements and environmental limitations increase utilizing both the parallel and partially coupled transmission lines. However, it is very demanding to find the fault point of the single phase to ground faults owing to the mutual coupling which does exist between the two circuits in these transmission lines. Furthermore, in practice, most of the transmission lines are not transposed, which makes the fault location problem more challenging. In this paper, by presenting the simulation results of the fault location for a parallel line, it is revealed that for the untransposed lines, the two-ended fault location approach based on the zero sequence network has a better performance as compared to the negative sequence network based methods addressed in the technical literature. In this regard, this study deals with proposing a new ground fault location methodology for partially coupled transmission lines. Therefore, the fault location equations based on the zero sequence network are derived and presented for both operation modes, including 1) both lines are in service, and 2) one line is in service, and another one is disconnected and grounded at both sides. The proposed method can also be applicable for the parallel lines if the parameter associated with the mutual coupling is altered. This fault location approach employs the measured voltage and current phasors at both sides of the line. Furthermore, in order to assess the accuracy of the presented method, extensive simulation studies of untransposed partially coupled transmission lines are carried out in the PSCAD/EMTDC software. To this aim, the proposed method performance against different fault resistances, source impedances, measurement errors, arcing faults, compact towers, line length, and two-phase to ground faults is investigated. The simulation results demonstrate that the proposed method provides very good accuracy for fault location.