Dual use line relays to improve power swing deblocking function

•Dual use line relay based power swing de-blocking scheme is proposed for first time.•All possible fault cases are considered including critical power swing situations.•Detect faults even for series compensated lines, single/multi-modal power swings.•Efficiency of proposed algorithm has been verified with noisy signals too. Shrill power swing due to various electrical disturbances may lead to malfunctioning in distance relay and intimidating stress on the power system equipment. If fault occurs during power swing that is more dangerous and should be detected as early as possible for secure and stable operation of the power system. The power swing blocking (PSB) and de-blocking (PSD) functions are essentially kept in the distance relays to address this issue. In this paper, a novel approach has been proposed with dual use line relay (DULR) to discriminate faults from power swing and thus improving PSD function. The proposed method is investigated for fast and slow power swing, various faults with a wide range of fault resistances (Rf), power angle variations, various levels of compensation, large load rejections, asymmetrical swings, and close in-far end faults. The robustness of the proposed algorithm has been confirmed by performing a large number of simulations on single machine infinite bus (SMIB) and WSCC 9-bus systems. It has been perceived that the proposed method is giving better results with improved PSD functions than the existing methods for fault detection during power swing.