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Analysis has been performed of the transmission of electric energy through the power distribution networks of PJSC Krasnoyarskenergosbyt over the period of 2016 – 2022. The structure of the company is considered, the characteristics of the main elements of the studied power networks are given, the degree of wear of the main electrical equipment is estimated. Based on the information from public media on the level of accidents in the company's power networks, an estimate has been made of the number of emergencies that occurred during the study period, the share of self-healing failures in the total amount of damage has been determined. The duration of interruptions of power supply to consumers, as well as the amount of undersupply of electric energy caused by these interruptions, has been estimated. The influence of the seasonal component on the number of emergencies during the study period is considered. Based on the data for the first half of 2022, the analysis of the main causes of damage to the elements of electrical networks has been performed. The classification of failures is made, with their main characteristics over the period under study considered. The possibility of using various methods of forecasting the reliability level of the power networks under consideration is evaluated. The results of the analysis of the use of statistical and cybernetic methods of preventive assessment of undersupply of electrical energy are presented. Based on the comparison of the results obtained, it is concluded that statistical methods are the most effective. The research uses general scientific methods, numerical methods of analysis, methods of the theory of electrical circuits, theories of mathematical statistics, data interpolation and forecasting. To visualize the results of the analysis, the technologies of the MATLAB graphics editor were used. The results obtained may be of interest to the heads of power grid companies, as well as researchers and engineers engaged in research in the field of reliability of power supply.

The article discusses in detail the issues related to the electric energy transmission through the electric PJSC Rosseti Lenenergo networks over the 2014 - 2021 operation period. The purpose of the article is defined as a study of the accident rate in the Company's electrical networks, for which a number of tasks to be considered are formulated. The results of annual reports on the number of failures in the Leningrad region and St. Petersburg electrical networks in 2014 - 2021, broken down by months, are used as source data. To approximate the series of emergency shutdowns, programming algorithms developed by the authors were used, which, through the technologies of the Matlab graphics editor, present the visualization of the studied characteristics. The structure of the electric networks on the Company's books, both in the Leningrad region and in St. Petersburg, is considered. The balance of electric energy for the period under study and the data on its losses during power transmission are analyzed. The assessment of the level of damage to electrical networks by events of stable and unstable failures was made. The principal causes of failures are classified, and their percentages related to the total number of failures across the Company's structural units is established. The relationship is established for the number of failures in particular months of the time period under study. The Company's plans of repair and restoration activities are considered, and the correlation coefficient concept is introduced, which establishes the relationship between the number of emergency shutdowns and the set of measures aimed at ensuring the reliability level for the uninterrupted functioning of electric power transmission facilities.

The article is a continuation of the study of operational reliability level of electric networks (EN) of PJSC Rosseti Lenenergo in 2014 – 2021. The classification of causes of damage in the EN and identification of predominant among them in the Company's EN during the operation period are considered in detail. The purpose of the article is defined as the study of cause-and-effect relationships that determine the accident rate, for which a number of tasks are formulated to be considered. The input data are the results of annual reports on the number of failures, broken down by months from 2014 to 2021 in the Leningrad region (LO) and St. Petersburg (SP) electrical networks. As research methods, numerical methods for evaluating the study results and the MATLAB graphic editor technology were used to visualize the analysis results of the studied indicators. Methods of mathematical statistics and artificial neural networks were used as preventive damage assessment methods.To approximate the series of emergency outages, programming algorithms developed by the authors were used, which enabled the visualization of the studied characteristics. It is established that the most appropriate solution is to use statistical methods based on the least squares method. With their application, it is possible to study trend-seasonal models that allow to assess the influence of the seasonal component on the number of failures of electric grid elements.As a result of the study, the main causes of failures of elements of electrical networks have been identified. For the networks of the LO, the main damage cause is the fall of trees (41%), for the SP networks — the impact of unauthorized persons and organizations (48%). Trend and trend-seasonal models have been constructed that allow obtaining short-term forecasts of emergency outages. At the same time, the assessment of the seasonal component reflects the dependence of the number of accidents on the month in which they occurred. For a more detailed analysis, it is planned to consider the influence of climatic parameters on the studied indicator.

The article presents the analysis of the Irkutsk Electric Grid Company activities over the years 2014–2021. The detailed characteristics of the company's balance activities in electric power transmission and its losses are presented, and the failure rate of the company's 0.38 to 500 kV electric networks is considered in detail. The number of failures of electric network elements for each year of the period under consideration, as well as the duration of power supply interruptions are determined. The ratio of self-recovering failures that are self-eliminated after actuation of automatic reclosing (AR) in the total volume of emergency situations has been found. The most characteristic periods of occurrence of the largest number of failures in the electric networks under consideration have been determined. The causes of failures have been considered in detail, and their analysis resulted in establishing that the key causes are the aging and wear and tear of electric network elements. The data are given on the percentage ratio of electric networks of several rated voltage classes, the service life of which exceeded the established normal values. The analysis is performed of the company’s financial expenses on development of electric networks and conformity of the planned measures to the fulfilled investments. It is established that the level of the company’s actual investments significantly exceeds the targets.The company's policy in reducing electric energy losses through the implementation of organizational and technical measures is analyzed.

Analysis has been performed of the operation of electric distribution networks of ten branches of Oblkommunenergo (OKE) of Irkutsk Region [1]. Based on the data on the operation of these networks published in public media, algorithms and computer programs for the Matlab graphic editor are compiled, which are used for plotting time diagrams that characterize the operation of the electrical networks under consideration. The balance changes are shown in the transmission of electric energy into the OKE networks and from the OKE networks directly to consumers (high, medium and low voltage networks). The number of failures, the power supply interruption time and the amount of electricity undersupplied in each month of the year for each of the branches are considered. The months of the year are determined, in which the greatest and least damage occurs to the electrical networks of the OKE branches. Data are presented on the dynamics of annual wear of electric networks, planned activities and their annual implementation. The level of reliability is considered according to the established indicators of the average duration of interruptions in the transmission of electric energy in each calculated regulation period. It is shown that the combination of the main causes of failures largely depends on the natural-climatic and terrain specifics of the regions through which the routes of electric networks pass. As an example, data on the causes of failure in the electrical networks of one of the OKE branches are considered. The most and least damaged electrical networks of the considered OKE branches have been established. In conclusion, findings are formulated and recommendations are presented on minimizing outages based on the main types of failure causes for the purpose of increasing the operational reliability of the electrical networks under consideration.

The purpose of the article is to analyze the damage rate of overhead power transmission lines (OPL) in medium-voltage electrical distribution networks of the Irkutsk region. The established International Indices that determine the level of reliability of the functioning of electric networks are considered, and information on the compliance of the condition of electric networks in Russia with these indices is analyzed. Analytical information on the damage rate of elements of these networks and their causes in Europe, America, and Russia is presented. The emphasis is placed on the fact that the most common damage is characteristic of overhead power lines, especially 6–10 kV lines. As an object of research, two branches of the Irkutsk electric grid company (IEC) were taken, one of which provides electricity to rural consumers, the other — mainly to consumers residing in the territory of the city Irkutsk. The characteristics of these electric networks, their territorial location and basic technical data are presented. To conduct analytical monitoring of the level of reliability of overhead power transmission lines, logs of disconnection of the Eastern and Southern electric networks of the IEC over a long-term period were used. On the basis of this information, tables of failures and their consequences in the studied electrical networks were compiled for monthly average data over the period under examination for various causes of damage. To plot time diagrams of the parameters under examination, computer programs were compiled in the Matlab system, the use of which made it possible to obtain visualization of changes in failures for various reasons for the electrical networks under consideration. The information on the time of power supply interruptions in these networks, as well as the amount of electricity underutilized by consumers during these interruptions and its cost are analyzed. It is shown that in the electric networks under consideration, most of the power failures are related to the territorial dispersion of these networks, and the low level of equipment controls and insufficient qualification of operating personnel, as evidenced by the significant number of failures for unknown reasons. Besides, a significant part of the failures is due to damage to the overhead line wires, switching equipment and the effect of wind load. Recommendations for improving the condition of power transmission lines and a number of measures aimed at improving the level of reliability of power supply are presented.

The influence of phase current unbalance on the probability of occurrence of fire-hazardous situations in industrial premises that receive power in various power supply systems is considered. The theoretical prerequisites for the occurrence of fire-hazardous situations are described. It is shown that zero-sequence flows flowing through a neutral conductor in an unbalanced mode significantly heat it, which can lead to short circuits and conditions for the occurrence of fires. The results of studies of unbalanced conditions in Russia and abroad are presented. It is shown that the zero-sequence flows resulting from current unbalance lead to an increase in additional losses of active power and electrical energy. It is proved that additional heat losses caused by unbalanced power consumption can destroy the insulation of neutral and phase conductors, which is the main cause of short circuits and, as a result, fires. Based on the use of the Matlab graphical editor, dynamic characteristics of variations in phase and interphase currents and voltages, as well as the power loss coefficient, which characterizes the increase in heat losses, are constructed. The analysis of fires and their consequences for various objects in the Russian Federation is made. A computational unit has been developed in Matlab, which is used for calculating and plotting the dynamics of fires and their consequences over the investigated period of time. It is shown that the occurrence of fires and their consequences due to violations of the rules of operation of electrical installations occurs in any premises and sometimes reaches more than 20% of all possible causes of fires. Methods and technical means of minimizing zero-sequence currents as a means of preventing the occurrence of fire-hazardous situations are considered. The principle of operation of an automatically controlled shunt-symmetric device with a minimum resistance to zero-sequence currents is described.

Disconnection of power consumers from power grids is quite a common event, with a wide range of consequences. Power supply interruptions can be caused by both casual events, and planned shutdowns. Disruptions in systems of power supply of consumers lead to a variety of adverse events (under-delivery of products, large-scale product rejection, failure of production equipment, etc.), which inflicts a significant economic damage. The retrospective analysis of the failure rate of electrical networks of the Right Bank and Left Bank districts of Irkutsk over 2013–2017 has been carried out. The analysis was based on the data from dispatching logs of observations on events of failures caused by emergency damage to the Southern electrical networks. It is established that the greatest number of failures occurs for such reasons as damage at substations, damage to consumer electrical networks, wire breakage in air and cable power lines as well as damage of switching equipment. Failures related to wind load, damage at packaged transformer substations, insulators and surge arresters are also analysed. The percentage rate of failures of electrical power networks caused by specific reasons from the total number of failures is presented. Besides, the analysis is performed of the duration of interruptions of power supply owing to damage of individual elements of power network equipment as well as the amount of electric energy undelivered for these reasons, and financial losses caused by these failures due to under-delivery of electric energy, with the average wholesale electricity prices taken into account.