Computer-aided design and testing of an accurate fault locator for EHV teed feeders

The basis of an alternative approach to accurately locating faults on teed feeders is described. The technique developed addresses the foregoing problems and in particular, takes into account the practical limitations in the design. The method utilises voltages and currents captured at all three ends of a teed feeder, which are than digitally filtered to accurately extract the power frequency phasors. Use is made of superimposed modal components of signals so as to minimise errors arising in accuracy due to line loading or source impedances and means is developed for effectively synchronising data from the three ends together with an accurate identification of the faulted branch, all essential requisites for achieving a high degree of accuracy. Finally, the fault location technique is evaluated using simulated results from practical 400 kV teed feeder configurations