DWT approach based differential relaying scheme for single circuit and double circuit transmission line protection including STATCOM

Abstract

This paper describes fault detection and classification in a double–circuit transmission line with presence of STATCOM (Static Synchronous compensator) in one circuit. DWT (Discrete Wavelet Transform) approach based differential relaying scheme is used to detect and classify the fault pattern in the above transmission line. The scheme starts with current signals extracted from both end of the transmission line synchronously and processed through DWT to obtain Spectral Energy (SE). The Differential Spectral Energy (DSE) is computed by subtracting SE obtained from both sending end and receiving end of the line which is the key indicator for fault detection and classification. The proposed scheme is extensively tested on faulted conditions with wide variation in operating parameters and the test result indicate that it can reliably detect and classify fault both in single and double circuit line in presence of STATCOM with a relay response time of less than one cycle. Keywords: Single circuit line, Double circuit line, STATCOM, SE, DSE, Rf, SI, FIA