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We propose a method for the fault passage indication of earth faults in resonant-earthed networks, based on phase current measurements alone. This is particularly relevant for electricity distribution systems at medium-voltage levels. The method is based on the relative magnitudes of the phasor changes in the phase currents due to the fault. It is tested for various network types and operation configurations by simulating the network in pscad and using the simulated currents as the input for an implementation of the method in matlab. In over-compensated networks, the method shows reliable detection of the fault passage, with good selectivity and sensitivity for both homogeneous and mixed (cable and overhead line) feeders. However, for the less common under-compensated systems, it has limitations that are described further in this study. The method has good potential for being cost effective since it requires only current measurements, from a single location, at a moderate sampling rate., Not duplicate with DiVA 1712785QC 20230918

Cross-Country faults (CCFs) are characterized by the situation when two phase-to-earth faults are simultaneously active on different phases at different locations in a network. Specially for resonant-earthed systems the current through the earth during a CCF becomes many times higher than during a single phase-to-earth fault. So far, few studies have been carried about these faults on resonant-earthed networks, specially evaluating the performance of distance protection. In this paper, simulations in RSCAD/RTDS® using real data obtained from a resonant-earthed network in Scandinavia are performed and different effects on distance protection are simulated. Four types of CCFs showing different patterns are defined and explained. Phase-to-phase loops of distance protection proved to be quite ineffective to protect against CCF faults since the fault outside the protected line/cable increases the impedance path. Phase-to-earth loops are accurate for low-resistance faults in a conductor with single infeed (Types I and II). However, when the line/cable is fed from both ends, some challenges can appear (Types III and IV). For Type III, the non-faulted Ph-E loop can be measured inside the protection zone due to the high residual current while for Type IV Ph-E loops will have problems to operate at all due to the lack of residual current., QC 20240711