Novel Sensitive Current Differential Protection of Transmission Line

This paper proposes a novel approach for sensitive current differential protection of transmission line. The improvement in sensitivity is a result of adaptive control of the restraining region in a current differential plane. The discriminant function used in differential protection corresponds to the ratio of series branch current in the pi- equivalent model of the transmission line. It requires time synchronous measurements which can be obtained from Global positioning system (GPS). Electromagnetic transient program (EMTP) simulations on a four machine ten bus system are used to substantiate the claims. The results brings out the superiority of the proposed approach.