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The article discusses an algorithm for determining the fundamental harmonics of currents and voltages in the measuring devices of relay protection at saturation of the magnetic circuits of current transformers. The aperiodic component arises due to the presence of complex resistances of generators and power lines in the parameters of the power system. Periodic components appear in microprocessor technology due to imperfection of the measuring devices. The exclusion from the short-circuit current entering the measuring devices of relay protection, non-periodic components and harmonics, except for the first one, makes it possible to increase the reliability of relay protection.

The paper addresses the problem of relay protection malfunction under the condition of saturated state of the current transformer magnetic core. The first part of the paper provides an overview on how this problem is solved in the related studies. The pros and cons of the existing approaches are highlighted and discussed. A method for reducing the influence of aperiodic components on the operation of digital relay protection is considered in detail. An algorithm for eliminating the aperiodic component in the current of the measuring element relay protection, caused by the saturation of current transformer cores, is shown and described as a simple step-by-procedure, providing the opportunity of its real-time applications. The authors focus the discussion and concluding remarks of the paper on the major advantages and the promising application spheres of the proposed approach. All the calculations provided in the case study section are based on real metering data.

This paper describes the method of determining a location of short circuit on transmission lines when saturation of current transformers magnetic cores and aperiodic components in measured currents are there. The method is based on measuring ratio of the reverse sequence current on one side of a line to the current on the other side. It is shown how to exclude the aperiodic component in measured currents. It is shown that four samples of currents in the initial short-circuit period are sufficient to determine all the parameters of mode necessary for the implementation of relay protection and determination of short-circuit locations.

The authors propose the algorithms to calculate the actual values of currents and their derivatives. The algorithms allow a sharp reduction in the aperiodic components of currents in the calculated actual values and their derivatives. The algorithms are developed to calculate the instantaneous values of positive- and negative-sequence currents when the information obtained during a time interval equal to two milliseconds or less is used. An algorithm is devised to calculate the sinusoidal components of the currents in the presence of aperiodic components in the samples. To eliminate the disoperation of digital relay protection and improve the accuracy of fault location, it is necessary to eliminate the influence of aperiodic components in the currents drawn to the measuring devices of relay protection. The algorithm completely eliminates the aperiodic component at any time constants and is implemented by four samples of currents. The four samples of currents separated by three sampling intervals are sufficient for calculating all the parameters of currents, including the positive and negative-sequence currents, in particular in the case when the magnetic cores of current transformers reach saturation. The proposed methods for setting the industrial frequency parameters to avoid the aperiodic components in short-circuit currents are based on the algorithms that process the data from three and four samples of currents.

In this paper, a method of samples of instantaneous currents and voltages is proposed, which allows to extract only sinusoidal information necessary for correct operation of digital relay protection and automation from information containing instantaneous values of currents containing periodic and aperiodic components. The studies were performed based on the analysis of the equations of short-circuit currents in electrical networks. The time during which the current and voltage parameters are sampled does not exceed 2 milliseconds, which is less than 1/8 of the industrial frequency period. The method made it possible to implement protections, which fix damage with a help of analog devices only for several periods of current change. At the same time, the protections implemented by analog devices are not free from errors introduced by aperiodic components. Principles for the implementation of directional protection of generators and transformers are proposed. Directional protection of generators and transformers is feasible in the presence of information about the modes of the electrical network elements that are connected with the protected ones. The proposed four-sampling method allows to implement all protections that react to periodic components of currents and voltages using only four instantaneous values of currents and voltages obtained within two milliseconds or less after the occurrence of a short circuit.

A complex infrastructure and transport scheme of fuel supply, long and busy power lines, extreme continental climate with temperature changes from -50 to +45 oС - all these factors have a negative impact on the quality of electricity. There is high probability of accidents due to the unreliability of electrical networks. This paper describes a method of power supply to remote consumers of "low" power without the construction of high-power transformer substations and the use of diesel generators

This article gives a comparative assessment of the efficiency of electricity production and consumption in the Western Economic Zone (WEZ) of the Republic of Sakha (Yakutia), following the results of the research work ‘Assessment and the Main Trends in the Change of the Natural and Socio-Economic Status and Human Potential of the Western Economic Zone of the Republic of Sakha (Yakutia)’ within the framework of the program of comprehensive scientific research under the state contract N5329 of August 7, 2017. Based on the analysis, the existing risks of electricity supply in the WEZ areas are identified, and recommendations for effective electricity consumption and production in the WEZ areas are developed. The study makes it possible to develop comprehensive recommendations for increasing the efficiency of electricity production and consumption in the WEZ areas. No similar studies have been conducted for the WEZ of the Republic of Sakha (Yakutia) in the past five years. In this regard, the study is significant because both natural and cost indices of electricity production and consumption are calculated for the first time, and recommendations for effective electricity consumption are given in the context of the WEZ settlements. The study helps to assess the state of energy in the WEZ areas of the Republic of Sakha (Yakutia).