An assessment of the performance of distance and IDMT overcurrent relays for phase faults on interconnected power system networks

A computer program written in FORTRAN V has been developed for use in the assessment of the performance of inverse definite minimum time (IDMT) directional and nondirectional overcurrent relays, with or without high set elements, and distance mho relays or any combination of these. The algorithm can deal with multiple bulk supply points, parallel lines, parallel transformers, or three terminal lines (teed circuits). The algorithm allows for the creation of an island and can obtain the elements of the bus impedance matrix in the islanded and nonislanded parts which is not possible by direct matrix inversion or an ordinary outage procedure. The algorithm is applicable to three phase faults and has the capability to deal with all kinds of feeder configurations. Arrangements have been made to cover all parts of the feeder configurations as fault points