A negative sequence superimposed pilot protection technique during single pole tripping

This paper addresses negative sequence pilot protection (NSPP) issue as one of the most widely used protective principles for high-voltage/extra high-voltage transmission lines for faults during the single-pole tripping (SPT) condition. In this paper, a negative sequence based superimposed technique is proposed to provide a solution for the problems of NSPP during SPT condition. This method is able to correctly operate during SPT with different situations, including secondary arc, different fault types, high fault resistances, fault locations, change in source capacity, cross country fault for double circuit line, far end fault for double circuit line. The performance of the proposed method is evaluated using data simulated with ATP/EMTP for single and double circuit lines. A discrete Fourier transform (DFT) technique with one cycle window is developed to estimate the fundamental component. The data sampling rate was used at 6.4 kHz. Numerical studies show that the proposed scheme is simple and accurate and can be used for updating, improving, and refurbishing of the existing negative-sequence pilot protection relays. (C) 2016 Elsevier B.V. All rights reserved.