Impedance-differential protective algorithm for long power transmission lines

In this paper, the evaluation of the concept of impedance differential scheme for long transmission line protection is presented. Using the voltages and currents of both line ends, the differential impedance is calculated. Capacitive charging current which constitutes the main drawback of current differential protection is eliminated in presented protection method. What is more, the advantage of presented impedance differential protection is ability to determine the fault location. For evaluating the validity of considered protection scheme, computer simulation based on ATP-EMTP was carried out. The obtained results approve the high reliability of the impedance differential protection.