Mutual Coupling Compensation Techniques Used for Distance Protection of Parallel Lines

When a distance relay protects transmission line located on dual circuit tower, coupling effect will occur between the two circuits. Transposition of circuits can reduce mutual impedances, but this does not cater to zero-sequence impedance during earth faults. As result, measured by under phase-to-earth fault conditions in these circumstances represent correct point unless effects are taken into account. On multi-circuit lines, primarily if they operate parallel, should be considered when calculating settings for protection function. A 220 kV parallel sharing same tower was analysed using DigSilent Power Factory simulations. Phase-to-earth faults different configurations were system, and reach then estimated operation. The results confirm how overreach underreach scheme due influence coupling.