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This paper revisits the analysis of the well-known infeed effect on transmission lines distance protection. A new adaptive algorithm to overcome this drawback is proposed, which requires solely impedance data and the operational status of power apparatus to perform overreaching distance zones settings. A comparison of the proposed strategy and the traditional one is performed. The obtained results demonstrate that the proposed settings ensure the correct operation of overreaching zones. Thereby, the backup coverage is improved significantly, besides avoiding distance zones overlapping between adjacent lines. It reveals the proposed strategy usefulness and value from the practical point of view, since it can be implemented with technology readily available on the market. [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 new method for busbar differential protection based on the instantaneous power concept. In order to do so, the instantaneous power per phase of each network element connected to the busbar is computed by using the instantaneous current values and a voltage memory action strategy. The performance of the proposed technique is compared to one of the traditional instantaneous-current-based differential protection algorithms, which is widely used by manufacturers of commercial relays. Both internal and external faults, as well as evolving external-to-internal faults, were simulated in a power substation with double-bus single-breaker configuration using the software ATPDraw. The obtained results reveal that the proposed algorithm is twice or more faster than the traditional instantaneous-current-based algorithm for most of the internal and evolving external-to-internal faults, while ensuring secure operation for external ones even when severe current transformer (CT) saturation takes place, through a new harmonic power restraint strategy. Also, since the proposed method provides faster fault detection time, the requirements for CT time to saturate may be alleviated, guaranteeing correct operation even in the case of early CT saturation. [ABSTRACT FROM AUTHOR]

Abstract: A phasor estimation algorithm, which uses orthogonal full-cycle filters in conjunction with an adaptive filtering of the decaying DC component, is presented in this paper. The full-cycle orthogonal filters are designed using a technique which combines the maximum overlap discrete wavelet transform and the least error square algorithm. The decaying DC component elimination is performed using an adaptive digital mimic filter. The frequency and time responses of the proposed algorithm are compared with those of other full cycle algorithms reported in the literature on the subject. The obtained results reveal that the proposed algorithm rejects all harmonics, is less sensitive to interharmonics, presents better transient responses and can be faster than other full cycle algorithms. [Copyright &y& Elsevier]

Abstract: This paper presents a novel filter design technique based on the maximal overlap discrete wavelet transform (MODWT). Time and frequency response of the designed filters are compared to the ones of traditional discrete Fourier transform (DFT) based filters. The obtained results show improvements on response speed when comparing to full cycle traditional filters and improvements on frequency response when compared to half cycle traditional filters. According to these characteristics, the designed filter may be used in secure high-speed distance protection, since it provides fast relay operating times, without compromising their frequency response. [Copyright &y& Elsevier]

Highlights: [•] Studies have shown that lines little longer than half-wavelength are advantageous for bulk power transmission over very long distances. [•] We show that conventional fault location methods are not suitable for lines little longer than half-wavelength. [•] An innovative and non-iterative two terminal algorithm is proposed. [•] Extensive EMTP simulations attest the reliability of the algorithm for fault location on lines little longer than half-wavelength. [ABSTRACT FROM AUTHOR]