An Online Single-Ended Traveling Waves Fault Detection Algorithm for High-Voltage Multi-Branch Overhead Lines

This paper proposes a novel single-ended traveling wave-based fault location method for unearthed overhead lines with a complex topology. The low fault current magnitudes of a phase-to-ground fault in unearthed sub-transmission networks make ineffective the operation of the impedance-based protection. The proposed method decouples the dependence of the traveling waves propagation modes on the speed propagation of the line, to release the analysis of a multi-branched non-homogeneous line by means of a single measurement terminal. The combination of the results obtained by analyzing different propagation modes allows to determine the fault distance with errors in the order of tens of meters. The proposed method has been applied to a multi-terminal and branched unearthed overhead line simulated in EMTP-RV environment to identify 20 different faults, 10 before the line branch and 10 after it. In the majority of the tested fault cases, the proposed technique allows identifying the fault location with an average error lower than 0.3%. For faults in critical positions, for instance close to the line branch or to the measurement terminal, the average error is lower than 10%.