Faulty Line Identification Algorithm for Secured Backup Protection Using PMUs

Abstract

In this paper, a technique for identification of faulty line in a power system is proposed using phasor measurement units (PMUs). The identification is accomplished in two steps (i) detection of bus nearest to fault point and (ii) detection of faulty transmission line connected to that selected bus in step (i). The bus voltages and line currents associated with the non-PMU buses are computed from the available PMU data. Using maximum percentage deviation of bus voltages during fault, the bus nearest to the fault point is detected. With PMUs at all buses, faulty line identification can be accomplished by comparing the angles of positive sequence currents of all connected lines to the selected bus. However, with limited number of PMUs, phase angle comparison method becomes unreliable. Under such situation, comparison of fault voltage magnitudes (VMs) of the selected non-PMU bus computed from all connected routes is used to identify the faulty line. When the selected bus is a PMU bus, % deviation of VM of its connected buses is used to identify the other end of the faulty line. The effectiveness of the proposed technique is tested on IEEE 9-bus system and Northern Region of Electricity Board 391-bus, an Indian utility system. The usefulness of the faulty line identification in supplementing protection decision is also demonstrated for secured backup protection.