A Compensated Impedance Based Ground Fault Locator for an Unearthed Power System

Abstract

Continuous operation of a power system during a ground fault can be achieved by employing either a High Resistance Grounded (HRG) power source or a floating power source. However, if a second ground fault occurs in the system it can cause significant problems and therefore the presence of the First Ground Fault (FGF) must be detected, located, and repaired quickly. In this study, an active impedance based fault location method is proposed to locate the FGF in a HRG power system. The study presented shows that the magnitude of the fault resistance has only a small influence on the proposed technique. However, for unbalanced faults, the impedance of the healthy phases can distort the impedance measured and impair the accuracy of the fault location method. Therefore, a new compensated method is proposed to compensate for this distortion. The results show that a high accuracy can be achieved with the compensation, with a location error lower than 5%.