Earth Fault Protection System for Distribution Lines Considering the Increase of Capacitance to Earth of Distribution System

Abstract

The increase of capacitance to earth of distribution system would make it difficult for the conventional earth fault protection system for distribution lines to locate and isolate an earth fault. Therefore, the authors propose a new method in consideration of the increase of capacitance to earth. The proposed method combines three relays with different protectable ranges to detect an earth fault. Specifically, earth faults are detected by measuring zero-phase voltage, zero-phase current, and residual voltage. In addition, the use of both zero-phase voltage and line-to-line voltage ensures the selection of the fault line. This paper clearly shows the usefulness of the proposed system by graphing the protectable range of each protection relay. In addition, this paper implements the proposed system using IEDs, which are general-purpose protective relay devices and reports the results of the verification test by Real Time Simulator.