Simulation on single-pole tripping of phase segregated current differential relay protection for six-phase feeder in digsilent powerfactory

Converting an existing double-circuit three-phase (3Φ) line into a single six-phase (6Φ) transmission feeder operating at a higher phase-to-ground voltage increases the power transfer capability. The use of 6Φ transmission complicates possible short-circuit fault conditions and the number of significant fault types increases to 23, with 120 possible different combinations. The impact on system stability of tripping the entire feeder may be unacceptable, and consequently single pole tripping is required. This paper investigates the suitability of applying a phase segregated current differential protection scheme with single-pole tripping to a simplified 6Φ network, modelled in DIgSILENT PowerFactory®. The conventional 3Φ tripping logic was modified to ensure the correct single-pole tripping results were obtained for all fault types.