A comparative study of DFT and Moving Window Averaging technique of current differential protection on Transmission line

Abstract

This paper is based on the study of current differential protection scheme on transmission line by using Moving Window Averaging technique and Discrete Fourier Transform. From the beginning of the history of power system, researchers have tried to increase the speed and sensitivity of transmission line protection in the power system protection field without compromising the security. Current differential protection scheme always provides sensitive protection with sharp discrimination of the disturbance area from the protection zone. Current differential protection scheme is immune to power swings and load encroachment. In the first method DFT, we can easily measure the phasors of the two ends of the transmission line which is very much essential for power system. With the help of moving window averaging technique extraction of the dc component of the current of transmission line is possible from both the sending and receiving ends. It is shown that under steady state condition, the differential current is zero while an internal line fault leads to non-zero differential current. The transmission line model is simulated with the help of PSCAD software.