Numerical conic distance relay

Relays are the key device that is used for the protection of a power transmission system. The paper presents the development of a numerical distance relay, based on conic characteristics. The developed distance relay is intended for the protection of transmission network so that the scheme would exclude most of the conditions for which tripping is undesirable (arc resistances and power swings). The Conic characteristics have been plotted and are tested by injecting faults. The characteristics which is developed 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 Conic is highly suitable for protection of medium, high and extra high voltage transmission line during faults.