Enhanced distance-protection algorithm for accurate fault location and resistance characterization under double phase-to-ground conditions
I. San Sebastian(1,2), Marene Larruskain(1), Felipe Uriondo(1), Itxaso Aranzabal(1) 1. Department of Electrical Engineering, UPV/EHU University of the Basque Country, School of Engineering Bilbao. Bilbao, Spain 2 INGETEAM.Power Technology, Parque Tecnológico de Bizkaia, Zamudio, Spain 2026-06-27

Abstract

The distance-protection function is employed tosafeguard high-voltage transmission lines against single-phase, double-phase, double phase-to-ground, and three-phase faults. In radial systems, or in double-end-fed configurations with homogeneous networks where the line is protected from the strong source end, the accuracy of conventional distance protection methods is inherently constrained. This paper presents a robust solution for accurately estimating the fault distance during double phase-to-ground faults as well as the fault resistances. The algorithm considers two scenarios. One for equal fault resistances in the two involved phases, a condition that keeps the sequence networks decoupled and permits the use of sequence-domain measurements. The other scenario involves unequal phase fault resistances, which couple the sequence networks and therefore require phase-domain voltage and current measurements. Together, these cases cover the full range of resistance configurations, ensuring a thorough and reliable proposed approach. The algorithm is validated with simulations and a real field fault case.

Key words: Distance Protection, Fault Location, Fault Resistance.

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