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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]

This paper revisits the generalized alpha plane (GAP) formulation applied to differential protection of multi-terminal apparatus. The GAP formulation is improved by aiming for three main goals: 1) control over the internal fault settlement region (FSR); 2) enabling a simple operation characteristic instead of a restraint characteristic; and, 3) The adjustments are not dependent to the device type. For this purpose, the GAP formulation is redefined in terms of two settings, which transform the FSR into a circumference with a controllable center and radius. Thereby, a circular operation characteristic with an adjustable radius is enabled around the FSR, for to improve security. To validate and test the performance of the improved GAP, numerous computer simulations have been carried out using Alternative Transients Program on different multi-terminal equipment (i.e., busbars, transmission lines, and power transformers). Furthermore, massive data analysis is held as a means to highlight the GAP's sensibility. The obtained results demonstrate a well-stable pre-fault point, a consistent circular FSR, and the effectiveness of the improved GAP even under severe conditions. [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]

This paper presents a new wavelet-based busbar differential protection algorithm, named as 87BW function. The instantaneous current-based differential protection fundamentals are taken into account and the well-known 1-out-of-1 and 2-out-of-2 tripping logics are mapped into the wavelet domain. Operating and restraint wavelet coefficients energy of currents are computed, regarding station configuration and bus zones boundaries. Thereby, the proposed 87BW function can be properly used in both static and dynamic busbar configuration. Its performance was evaluated through EMTP-based simulations of faults in a 230 kV power substation with double bus single breaker configuration. The obtained results reveal it provides ultra-high-fast trip for internal and evolving external-to-internal faults, guaranteeing security for normal through-load and external faults as well, even in the case of early and severe current transformer saturation. [ABSTRACT FROM AUTHOR]

This study proposes a new concept of transmission line differential protection based on an alternative alpha plane of incremental complex power, where the restraint characteristic is simply defined as its left‐half‐plane, so that no settings are required to define it. As the incremental complex power is evaluated per phase, the proposed algorithm is inherently phase segregated, not requiring additional faulted phase selection logics. A simple harmonic restraint strategy along with an external fault detection logic provides security for external faults with current transformer saturation. Aiming to evaluate the performance of the proposed algorithm, a wide variety of fault scenarios are simulated for a 500 kV transmission line 200 km long using the Alternative Transients Program. The obtained results reveal the proposed algorithm provides a fast and reliable line protection, being robust against variations in fault parameters, sources strength and loading conditions, as well as power swing situations and line energisation manoeuvres. Accordingly, one can suppose the proposed algorithm might be successfully used in numerical transmission line relaying. [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]

• Commutation failures on LCC-HVDC systems cause distortion on voltage and current waveforms of nearby AC system, leading to phasor estimation errors. • Half-cycle algorithms suffer more from inaccuracies than full-cycle ones when quite distorted signals are evaluated, revealing the use of short windows may be an issue for protection schemes in these scenarios. • Zone 1 of distance relays may misoperate, overreaching close-in externals faults. To overcome this drawback, the zone 1 reach can be reduced, or it can be deactivation as a more conservative approach. • Both phase and sequence line differential elements operate correctly, even during commutation failure of LCC-HVDC systems, preventing false trip command issuing for external faults. • Directional overcurrent element operated correctly most of time. However, zero and negative sequence elements may misoperate for phase-to-phase and three-phase faults. Therefore, it is recommend not choosing small pick-up values for this function. Commutation failure (CF) is an inherent issue for Line-Commutated Converter (LCC) HVDC technology. Whenever it happens, voltage and current waveforms throughout the AC system in the near vicinity of LCC-HVDC links become quite distorted. In this paper, it is assessed the impact of such kind of distortion on transient response of phasor estimation algorithms and, in turn, on the performance of AC transmission lines protection. Different discrete Fourier transform (DFT) based algorithms are implemented, and distance, differential and directional protection functions are evaluated. The obtained results reveal that phasor estimation errors arise whenever CFs take place, which may lead protection functions to misoperate, such that false trip command may be issued for external faults. [ABSTRACT FROM AUTHOR]

• The current mapping strategy (CMS) can improve the performance of differential protection of series-compensated transmission lines compared to the regular alpha plane. • The protection engineer can adjust the CMS according to the desired emphasis (i.e., sensitivity or security). • The CMS operates correctly even under severe outfeed conditions or subsynchronous oscillations. • Transient studies and 1340 simulations with different pre-fault and fault conditions proved the effectiveness of the CMS. This paper presents a particular case of the generalized alpha plane called current mapping strategy (CMS) formulation applied to differential protection of series-compensated transmission lines. The proposed formulation presents two unique features, control over the internal fault settlement region (FSR) and the use of an operation characteristic (OC). The FSR and the OC are two concentric circles defined on the alpha plane. Additionally, the proposed CMS allows the user to adjust the center and radius of the FSR and OC, according to the desired sensitivity and security of the protection. To validate and test the performance of the improved CMS, numerous computer simulations have been carried out using the Alternative Transients Program (ATP) on a 400 km long series-compensated, 500-kV transmission line. Furthermore, analysis of an extensive database of cases is conducted to highlight the CMS's sensitivity. The obtained results demonstrate the effectiveness of the settings of the CMS and a smooth trajectory to the FSR. The CMS also proved to be stable and reliable even under severe subsynchronous oscillations and outfeed conditions. [ABSTRACT FROM AUTHOR]

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]

This paper investigates the effects of communication channel latency (CCHL) on time-domain line protection functions. The Alternative Transients Program (ATP) was used to simulate the monitored power system and to model both the analyzed relays and communication channels via MODELS language. By doing so, the need for extra long optical fibers for laboratory tests is overcome. To provide a reliable investigation on the CCHL effects, a time-domain relay model is firstly implemented and validated by comparing its response against an actual device. Then, the communication channel is set to properly represent practical CCHL values under different fault scenarios for transmission lines with different lengths. The obtained results show that including the CCHL effects on time-domain protection testing procedures is of utmost importance because, depending on the data propagation time through the communication channel, it may have a relevant influence in what we call here "race of protection functions". • Communication channel latency (CCHL) effects on time-domain protection functions tripping times. • CCHL have been disregarded in EMTP relay models. • Which time-domain protection function is fastest when CCHL is considered. • An ATP/MODELS relay model validated with an actual relay. • Race of time-domain protection functions. [ABSTRACT FROM AUTHOR]

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]

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]