Distance relaying of Untransposed parallel transmission lines in case of phase-phase inter-circuit faults

Abstract

• Untransposed parallel transmission lines are targeted for distance relaying. • Phase-phase inter-circuit faults are addressed in the distance relaying. • The ADALINE is developed for an accurate online estimation of the fault distance. • The proposed approach achieves fast fault tripping and an accurate fault location. • It tolerates noisy conditions and properly handles variable fault arc resistance. Distance relays at both circuits of the parallel transmission lines would miscalculate the right fault impedance during inter-circuit faults. This paper deals with the distance relaying of untransposed parallel lines in case of phase-phase inter-circuit faults. It is a challenging case compared to that of transposed lines due to the mutual coupling between all six phases of the line circuits. Considering a phase-phase inter-circuit fault with the fault arc resistance, the line circuit model is analyzed on a time-domain basis. Consequently, a mathematical equation with a linear combination of specified functions is derived. This provides a splendid opportunity to establish an ADAptive LINEar combiner (ADALINE) consistent with the equation derived. The ADALINE with its simple structure gives a fast and accurate online estimation of the fault distance, employing single-end measurements during the inter-circuit faults. Hence, achieving the fault location along with the distance protection is also made possible. The proposed approach is readily implementable without being dependent on the system configuration. It operates robustly against the dynamic fault arc resistance and tolerates the noise contamination. The simulations in PSCAD/EMTDC provide extensive sensitivity analyses validating the proposed approach performance, in respect of both the accuracy and swiftness, for various fault conditions.