A novel EHV transmission line protection of adequate fault-resistance sensitivity and faulted-phase selectivity

Abstract The summation impedance relay (SIR) is characterized by a strong sensitivity to high-resistance faults. However, previous studies have not made SIR completely immune to the adverse influence of distributed capacitive currents and have ignored its inherent deficiency of faulted-phase selectivity. Therefore, a novel protection scheme is proposed. First, by compensating distributed capacitive currents, an improved ground-type SIR (composed of ground distance relays) is created. Using this SIR, the identification of internal high-resistance faults is performed while guaranteeing security under external faults. Then, a novel phase-type SIR (composed of phase distance relays) is designed, based on which a suitable phase-selection algorithm is proposed to distinguish single-phase faults and multi-phase faults. Comprehensive simulations show the security and dependability of the proposed protection scheme in various fault scenarios, including non-linear high-impedance faults and series compensation scenarios. Moreover, the approach’s performance under power swings is investigated, revealing its complementarity with existing protection principles.