Fault Analysis Detection and Protection of Transmission Line By PSCAD

Abstract

Protection of electrical power systems is the major issue in power industry and for the protection of these electric power systems, current distance relays are widely applied due to their inherent simplicity, excellent sensitivity on internal faults and high stability on external faults. This work represented the problems on transmission line in different type of zones. The conventional digital distance relay used for the protection of transmission lines fed from one end. Therefore, algorithm for digital distance relaying is presented for the station of errors produced by the conventional digital distance relay during a high resistance single line to ground fault or line to line fault. In this paper the algorithm is based on digital computation of impedance, which uses symmetrical components of three- phase currents and voltages measured at the local end only. The distance is divided into zone 1,zone 2 and zone 3. This paper may help to identify the fault on a transmission line and also help to improve the power factor of the system. The proposed algorithm has been tested usings software for a single line-to-ground and line-to-line fault which consider wide variations in fault resistance, fault location, power factor, and short-circuit capacity of the source, the Power Systems Computer Aided Design (PSCAD) simulation environment. A 132 kV transmission line model was developed in PSCAD, and different fault conditions including Single Line-to-Ground (LG), Line-to-Line (LL), Double Line-to-Ground (LLG), and Three-Phase (LLL) faults were simulated and analyzed. The performance of the distance relay was evaluated based on voltage, current, impedance, fault location, and relay operating time under different fault conditions. The simulation results demonstrate that the proposed protection scheme accurately detects and classifies faults, identifies the fault location, and operates effectively within the predefined protection zones (Zone-1, Zone-2, and Zone-3). Among the analyzed faults, the Line-to-Ground fault was found to be the most frequent, whereas the Three-Phase fault produced the highest fault current. The study confirms that PSCAD is an effective tool for transmission line fault analysis and relay performance evaluation, thereby improving the reliability, selectivity, and security of modern power transmission systems.