Novel second zone acceleration technique for distance relay utilizing sequence voltages

Abstract

An algorithm for second zone acceleration of the distance relay utilising the sequence voltages along with healthy phases impedances is presented in this paper. Specifically, the algorithm employs variation in sequence voltage ratio indices to sense the single-pole remote circuit breaker operation (RCBO), while utilising both magnitude and angle of the healthy phase impedance for sensing three-pole RCBO operation. Additionally, the developed algorithm can also identify the faulty phases based on variations in impedance magnitude. To avoid false-trip during transient faults, impedance of the faulted phase before RCBO is compared with its value after RCBO. Performance of the proposed approach is validated for various internal and external faults covering addition of parallel link, presence of noise, different load angle, fault location, fault inception angle, fault impedance, source impedance and errors in measurement/transmission line parameters on an existing 230 kV transmission line modelled in PSCAD/EMTDC software. The results, obtained from both simulation as well as Hardware in Loop (HIL) simulation through laboratory prototype, designate that the proposed approach performs appropriately regardless of power flow direction, fault resistance magnitude, and light load conditions. The results also reveal that the suggested approach is able to accelerate trip within a cycle after RCBO event, which is comparable to or faster than many existing methods. Compared to several existing approaches in the literature, it also outperforms in terms of sensitivity, reliability and selectivity.