Fault-detection and out-of-step protection functions are two important requirements in distance relays while dealing with power-swing conditions. In the proposed research, the first part focuses on developing wavelet entropy-based out-of-step blocking function during stable power swing and tripping function during unstable power swing. The process starts at retrieving the current signal samples during power swing and process it through wavelet transform to derive singular values, used to find out Shannon entropy, called wavelet singular entropy (WSE). Further, the power swing indicators are computed to distinguish stable power swing from unstable ones. The second part computes WSE-based indicator to distinguish faults from power swing. The WSE blocks the relay during power swing and issue the tripping signal during fault conditions based on a set threshold. The proposed technique is extensively tested for different stable and unstable power swing conditions providing improved response time for fault detection during power swing and distinguishing stable power swings from unstable ones.
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