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An approach to detect the secondary arc extinction is proposed here for single-phase auto-reclosing of non-compensated transmission lines. It consists on the analysis of the line side voltage phasors in the modal domain to safely and rapidly identify the presence and the extinction of secondary arc in the line. The procedure can also determine the arc re-ignition if it occurs during the line dead time. Since the proposed approach requires only the voltage phasors at one line terminal, it can be easily implemented in existing Intelligent Electronic Devices (IEDs) with no additional hardware or equipment requirement. Data from the Brazilian Power Grid were used to generate the case studies through the Electromagnetic Transients Program (EMTP). Moreover, field recordings were used to validate the proposed approach. A qualitative comparison with existing methods was accomplished and the obtained results reveal the proposed scheme efficiency, reliability and robustness. [ABSTRACT FROM AUTHOR]

Highlights • A new power transformer differential protection based on the instantaneous-current-value negative sequence is proposed. • The ratio of the operating and restraint negative sequence current signals is integrated during the time. • A new harmonic restraint strategy is also proposed, to improve protection security for external faults with CT saturation. • The proposed method is able to detect turn-to-turn and turn-to-ground faults. • The proposed algorithm may be more sensitive and faster than the traditional differential elements. Abstract This paper proposes a new algorithm for power transformer differential protection based on the instantaneous-current-value negative sequence current signals, which are reconstructed in discrete time-domain from the negative sequence phasor for the different transformer windings. Aiming to provide a more reliable operation of the proposed method, the ratio of the operating and restraint negative sequence current signals is integrated during the time. Also, as a by product, a new instantaneous-current-value harmonic restraint strategy is also proposed, to improve protection security for external faults with current transformer (CT) saturation. In order to evaluate the performance of the proposed algorithm, a wide variety of faults are simulated in the Alternative Transients Program (ATP) by varying the fault type; short-circuited turns percentage; sources strength and the power system loading. The obtained results reveal that the proposed method is able to detect turn-to-turn and turn-to-ground faults even for 1% of short-circuited turns, in such way that it may be more sensitive and faster than the traditional differential elements widespread used by manufacturers in real world protection applications. Therefore, the developed algorithm is an excellent complement to the conventional differential functions, for the most faster and sensitive operations for internal faults involving few turns, and safe for external short circuits with CT saturation. [ABSTRACT FROM AUTHOR]

This paper presents a three-parameter transmission line high impedance fault (HIF) model for the Alternative Transients Program (ATP)/ATPDraw. Real-world HIFs caused by vegetation contact on lines belonging to a Brazilian utility are firstly investigated to identify representative features of the fault resistance behavior during the disturbance period. Then, a data regression method is applied to obtain a time-domain function which emulates the fault resistance. Finally, an ATP/ATPDraw transmission line HIF model is developed and described in detail. For the sake of simplicity, only three parameters are proposed to be used in the model, namely: Initial resistance, final resistance and resistance decaying time constant. To prove the proposed model is representative, real HIF records are compared against ATP/ATPDraw simulated ones. The obtained results show the proposed model satisfactorily emulates the effects of real HIFs. • High impedance faults (HIF) are challenging for transmission line monitoring schemes. • Reliable models are important to simulate HIF in Electromagnetic Transients Programs. • A reliable three-parameter HIF model is proposed, combining simplicity and accuracy. • HIF parameters to emulate real cases by means of the proposed model are obtained. • A detailed description of the proposed HIF model in ATP/ATPDraw is presented. [ABSTRACT FROM AUTHOR]