A USEFUL METHODOLOGY FOR ANALYZING DISTANCE RELAYS PERFORMANCE DURINGSIMPLE AND INTER-CIRCUIT FAULTS IN MULTI-CIRCUIT LINES

A methodology for evaluating and visualising the response of distance units most commonly used is presented. A general case, with different topologies, of a double circuit line is considered and different types of inter-circuit faults are treated. Single line and simple faults ar e simplified cases of the general one. Faults are treated by means of the adequate connection between the sequence networks, where different types of faults are represented by a resistances star associated to b oth lines and ground. Different combinations of these resistances resu lt in different types of faults. Fault conditions are introduced to se quence networks of the rest of the system through phase current contro lled current sources, and the resulting sequence voltages at the fault point are applied to fault resistances through sequence voltage contr olled voltage sources. To calculate faults the mesh analysis method ha s been modified to take into account the dependencies fixed by the con trolled sources. Real previous state of the Power System (load flow, s equence source impedances at both ends and sequence impedance between ends) is taken into account. A useful and reliable way of representati on is presented to obtain the expected response of different types of distance units in multi-circuit lines in presence of inter-circuit sim ultaneous faults.