Development of a Multi-characteristic Distance Relay

Distance relays are the vital protective device used for the protection of power transmission lines. The paper presents the development of a numerical distance relay, based on characteristics for the transmission line protection. The relay is developed on the conic and quadrilateral characteristics. It is intended to combine both the characteristics, so that, the protection scheme would exclude most of the conditions for which tripping is undesirable (arc resistances and power swings). The Conic - Quadrilateral characteristics have been plotted and the relay is tested by injecting faults. The developed characteristics contained the faults that occurred within the reach of the relay setting. The relaying logic is coded in MATLAB and the transmission system is simulated in Simulink. The result shows that the Multi Characteristic relaying scheme is highly suitable for protection of medium, high and extra high voltage transmission line during faults.