Utilising synchronised data for the localisation of high resistance earth faults irrespective of neutral treatment or type of load connection

Reliable localisation of earth faults on MV networks, particularly those of high resistance, is a major challenge for distribution utilities worldwide. The innovation outlined in this paper provides a universal solution for the localisation of earth faults with very high sensitivity for high resistance faults. It addresses all commonly used neutral earthing treatments, three-and four-wire systems, whether load is connected three-phase, phase-phase or phase-neutral, balanced or not. The impact of increasing penetration of distributed energy resources, especially inverter-based resources, is fully addressed. This new methodology captures data using distributed network sensors. The data is time synchronised using GPS clocking to within 1 µs. The master station applies fault capture algorithms including fundamental frequency detection, augmented fault inception transient detection and a novel waveform comparison technique. Results from MATLAB simulations, are presented. Sensitivity of at least 5 kΩ up to in excess of 10 kΩ have been achieved. Accurate and reliable localisation for downed conductors, covered conductors, reverse fed earth faults and broken (open circuit) conductor conditions, are achievable. A portable (handheld or drone based) ‘Navigator’ instrument supports field staff to find the precise fault location. Optional travelling wave sensors can also be installed at strategic locations to address problematic network sections.