Series-Compensated Double-Circuit Transmission- Line Protection Using Directions of Current Transients

This paper presents the development of a new protection method for series-compensated double-circuit transmission lines using current transients. Using the proposed method, the faulted circuit can be identified locally, by comparing the polarities of wavelet coefficients of the branch currents. Applicability of the proposed method is demonstrated using a 500-kV transmission system simulated in an electromagnetic transient simulation program. Comparisons with the conventional distance and phase comparison protection schemes show that the proposed method can provide faster and more reliable protection for the series-compensated double-circuit transmission systems. The security of the relay can be further enhanced if the fault direction information is exchanged between the relays at two ends.