Wavelet-based directional protection
Directional protection, fault classifier, wavelet transform
Fast and accurate faults classifier and protect ios are required to ensure the safety of the power system. In this
research, a directional protection with phase, positive sequence, negative sequence, and zero sequence units by
using the scaling coefficients of the real-time stationary wavelet transform (RT-SWT) is presented. The wavelet
coefficients are used as directional protection activators for fast detection of the fault inception time, whereas the
scaling coefficients are used to provide backup activators in accordance with the overcurrent protection. In addition,
a proposal to develop a fault classifier by using only the local currents associated with real-time boundary stationary
wavelet transform (RT-BSWT) and Clarke's transform is described. Evaluations prove the feasibility to rebuild the
traditional directional protection by using RT-SWT and provided better performance and faster operating time than
the conventional protection based on the discrete Fourier transform (DFT). The preliminaries results to the fault
classifier proved be feasible to identify all 10 faults types correctness. As new functionalities to directional
protection, the wavelet-based negative sequence unit can be used to identify the fault directionality to three-phase faults,
even with severe voltage sags without memory strategies, which is not possible with the conventional protection.