Protection of Parallel Transmission Lines Using Wavelet Transform

A new scheme to enhance the solution of the problems associated with parallel transmission line protection is presented in this paper. The scheme depends on the three line voltages and the six line currents of the two parallel lines at each end. Fault detection, fault discrimination, and calculation of the phasors of the measured signals are done by using wavelet transform (WT). By comparing the magnitudes of the estimated current phasors of the corresponding phases on both lines, internal faults on the parallel lines can be identified. Also, by calculating the distance element of the phases on which a disturbance is detected and having a very small current difference magnitude can enhance and strengthen the scheme. Studies show that all types of faults at different loading conditions can be correctly identified in less than one cycle of the fundamental frequency.