Differential voltage‐based fault detection during power swing

Abstract

Any incorrect action by the distance relay is harmful to the stability of power system at a power swing condition. In this respect, discrimination of faults from power swing should be fast and accurate. This paper introduces a new fault detection method using time derivative of voltage signals at swing condition. The sample interval between two successive peaks of the derivative of a voltage signal always remains above a minimum value during power swing, while its value decreases by a significant margin after the occurrence of a fault. This discriminating feature of the differential voltage is mathematically developed and applied to detect faults under swing conditions. A 9-bus-modified WSCC system is considered for validating the method, and the simulation is carried out in an electromagnetic transient programme. The method detects both symmetrical and unsymmetrical faults accurately and quickly at power swing condition for various fault locations, power angles, fault inception times, fault resistances and swing frequencies. Its performance is satisfactory for series compensated lines and under noisy condition. The fault detection results and the comparative study with two available methods justify its potential.