Differential energy based relaying for thyristror controlled series compensated line

The paper presents a new approach for protection of 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 S-transform to generate the time-frequency contours (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 on the differential energy. 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.