Differential energy based relaying for thyristor controlled series compensated line

The paper presents a differential energy based protection scheme for transmission line including Thyristor Controlled Series Compensator (TCSC) using time-frequency transform such as S-transform. Initially the current at sending and receiving ends are retrieved and processed through the time-frequency transform such as S-transform to generate the time-frequency patterns (frequency contours). Spectral energy content of the frequency contours of both current signals are calculated and differential energy is computed to register the fault patterns in the transmission line. The tripping signal can be issued based on a set threshold, within two cycles from the fault inception, meeting the speed criteria of the digital relay. The results indicate that the differential energy based protection scheme can reliably detect the fault patterns in TCSC line including wide variations in operating conditions of the faulted power network. (C) 2012 Elsevier Ltd. All rights reserved.