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THE RELEVANCE of this study lies in solving the problem of reliable functioning of elements of energy systems and ensuring their effective operation during open-pit mining. The paper presents a methodological approach that allows us to assess the level of reliability of low-voltage asynchronous electric motors in a coal mine with complex mining, geological and climatic conditions of production. THE PURPOSE of the work is to quantify the operational factors affecting the service life of an asynchronous electric motor with a short-circuited rotor. Attention is focused on how influencing factors, different in physical basis, among which electrical parameters are highlighted – the coefficient of voltage asymmetry in the reverse sequence, the coefficients of harmonic voltage components and environmental parameters – temperature, air humidity and dustiness, affect the dynamics of changes in the service life of an asynchronous electric motor. Asynchronous electric motors used at one of the enterprises of JSC SUEK in the Trans-Baikal Territory are considered as an object of research. METHODS. The main tool for the implementation of research tasks is computer modeling based on the Matlab software package. RESULTS. The studies were performed on an asynchronous electric motor with a short-circuited rotor with Ph = 3 kW, rated speed 1500 rpm. The simulation of the operating mode of the electric motor under study was performed by changing the experimental parameters: the values of the total coefficient of harmonic voltage components (KU) – from 4 to 12% with a range of 2%; the values of the voltage asymmetry coefficient in the reverse sequence (K2U) – from 0 to 4% with a range of 1%; the ambient temperature (∆Tокr) – from -30°C to +30°C with a range of 10°C; air humidity values (Vc) – 20% and 60%; dust thermal conductivity coefficient values (Kт) – 0,12 and 0,28. Based on the obtained research results, diagrams are constructed that clearly illustrate the dynamics of changes in the service life of an asynchronous electric motor depending on the combination of influencing factors. CONCLUSION. The trends in solving the issues of reliable functioning of a coal mining enterprise with the presence of asynchronous electric motors and ensuring their efficient operation are the most priority, mainly focused on maintaining the stability of technological processes and maintaining the production volumes of a coal mining enterprise. The stability of the electric motor to certain influencing factors is estimated and their critical values are established. Recommendations on the use of asynchronous electric motors are formulated, taking into account their operating conditions.

THE PURPOSE. Development of digital models to determine the modes of double ground faults in 6-10 kV overhead signaling lines supplying signaling, centralization and automatic blocking facilities.METHODS. To create the models, methods of multiphase modeling of electric power systems were used, based on the use of lattice equivalent circuits from RLCelements connected according to complete graph circuits. For modeling, the industrial software package Fazonord, developed at the Irkutsk State Transport University, was used.RESULTS. The developed models provide correct accounting of all factors influencing the modes of double ground faults, including increased electromagnetic influences of the traction network. In contrast to known approaches, the dynamics of changes in these influences caused by variations in traction loads during train movement are modeled.CONCLUSION. The proposed approach to modeling double ground fault modes is universal and can be used for standard traction power supply systems, as well as promising high-voltage traction networks. The results obtained can be used in practice to configure relay protection devices for overhead signaling lines in order to reliably detect double ground fault modes and take measures to eliminate them. In addition, the modeling methodology presented in the article can be used when selecting measures to improve the reliability of power supply to signaling and automatic blocking facilities that ensure the safety of train traffic, as well as to develop methods and algorithms for determining distances to places of double ground faults in overhead power lines feeding signaling facilities , centralization and autoblocking. The presented results confirmed the effectiveness of the proposed approach for modeling double ground fault modes.

An algorithm for eliminating aperiodic components from short circuit (SC) currents is proposed. The algorithm is implemented by computer technology and allows you to determine the location of a short circuit and phase loss in 0.5 - 0.6 milliseconds. During such a time interval, saturation of the magnetic circuits of current transformers (CTs) does not occur, and the processors receive undistorted information from the CTs. To implement the algorithm, four measurements of instantaneous current values, separated by equal time intervals (sampling intervals), are sufficient. Elimination of aperiodic components increases the accuracy of determining the location of the fault. The algorithm can be used to determine the location of phase failure, and in digital relay protection based on measuring currents and voltages.

THE PURPOSE. A study of the influence of coordinated control of electricity storage devices and distributed generation installations on the operating modes of a network cluster, which is an electrical distribution network connected to the AC railway power supply system through a direct current insert (DCI).METHODS. The studies were carried out using a simulation model implemented in the MATLAB system.RESULTS. The following disturbing influences were considered: turning off the main power supply of the network cluster from the DCI side for 0.5 seconds; three-phase short circuit with a duration of 0.5 s at the end of a 6 kV cable line with a length of two kilometers. The simulation results showed the effectiveness of coordinated control of electricity storage devices and a turbogenerator with self-adjusting predictive controllers. On this basis, the values of overshoot of the rotor speed are reduced and the transient process time is reduced for all parameters in various modes. For example, the transient time for the generator rotor speed in the mode of connecting an additional load is reduced by three times, and for voltage - by two times.CONCLUSION. Based on computer modeling, it is shown that coordinated control of electricity storage devices and a turbogenerator with predictive regulators reduces the amount of rotor speed overshoot to almost zero and reduces the transient process time by almost 90%. It is advisable to conduct further research on the application of the method of coordinated control of active elements used in the power supply system to regulate the mode parameters.

RELEVANCE. An urgent task is to improve the reliability and quality of power supply. Very often, failures in operation are caused by damage to overhead and cable lines. Traditionally, a fairly large number of violations occur in the share of electrical distribution networks. For the reliable functioning of power systems and uninterrupted power supply to consumers, it is necessary to identify and eliminate faults in a short time to minimize damage. Thus, a method for efficient, accurate and reliable fault location is needed for both utility companies and consumers. To solve this problem, it is necessary to quickly obtain information about the state of the distribution eclectic network. THE PURPOSE. Reducing the time to search for a fault location in electrical networks, reducing damage from downtime for undersupply of electricity by analyzing existing methods for determining the location of faults on a power transmission line and developing a method for its prompt detection in electrical networks. METHODS. The basis of this method is a preliminary theoretical calculation of short-circuit currents in various sections of a power line. Based on the values obtained as a result of the calculation, the measured values of the short-circuit currents are compared with these values, on the basis of which the location of the line damage is determined. An algorithm for searching the left and right boundaries of the short-circuit current value in an ordered array of statistical data has been developed. RESULTS. A method for quickly determining the location of a short circuit is proposed, which is based on the use of a data array of theoretically calculated short circuit currents. The presented algorithm is able to accurately determine the coordinates of the short circuit in electrical networks. CONCLUSION. The proposed method for determining the location of damage to the power line allows you to increase the efficiency of determining the point of a short circuit and thereby reduce the time to eliminate the accident, and therefore, economic losses from undersupply of electricity.The basis of this method is a preliminary theoretical calculation of short-circuit currents in various sections of a power line. Due to the subsequent comparison of the measured values of short-circuit currents with the values of the calculated values, the location of the damage to the power line is determined. The presented algorithm is designed to accurately determine thecoordinates of the short circuit location, which can significantly reduce the search time and improve the accuracy of determining the fault location in the range from 100 to 150 m, regardless of the length of the power line, which significantly reduces the time to search for damage at the same time as solving the problem of reducing downtime , as well as minimizing damage both for guaranteeing suppliers represented by electric grid companies, and for consumers represented by industrial and agricultural enterprises.

THE PURPOSE. The relevance of research is that the comprehensive substantiation of issues aimed at ensuring the effective functioning of the electrical complex with the presence of an electric motor load in conditions of low-quality supply voltage. The aim of the work is to study the effect of the asymmetry of the supply voltage on the service life of an asynchronous motor with a short-circuited rotor. The main attention is paid to the dynamics of changes in the service life of low-voltage asynchronous electric motors of various series, depending on the level of voltage asymmetry. Asynchronous electric motors of the classic series (4A, AI) and the upgraded (5A, AI’) are identified as the object of research. As is known, the efficient and reliable operation of electric motors is characterized by the service life of the insulation of the windings. A qualitative assessment of the operational reliability of AM is determined by the accuracy of forecasting the real life of their service. That is why, it becomes obvious, the task of an adequate assessment of the operational reliability of low-voltage asynchronous electric motors operating under conditions of low-quality supply voltage directly depends on the complex of studies of such an external influencing factor as the asymmetry of the supply voltage. METHODS. The realization of the research objectives was carried out using the software package "SimPowerSystems" of the interactive programming environment Matlab/Simulink. RESULTS. The research was carried out on asynchronous motors with a short-circuited rotor: classic series (4A132S4, AIR160S8), upgraded series (5A132M6, AIR132S4) with PH = 7,5 kW, rated speed n = 1500 rpm. Modeling of the physical processes of the studied electric motors was carried out by changing the voltage asymmetry coefficient in the reverse sequence (K2U) from 0 to 5% in increments of 1%. Based on the obtained simulation results, diagrams of the change in the service life of AM from the magnitude of the influencing factor are constructed. The studies performed using computer modeling based on the "SimPowerSystems" software package of the Matlab/Simulink system made it possible to predict changes in the service life of AM, estimate the limits of permissible values of the voltage asymmetry coefficient in the reverse sequence, compare the studied electric motors by the level of resistance to an external influencing factor. CONCLUSION. A comprehensive solution to issues related to improving the operational reliability of low-voltage asynchronous electric motors is one of the priority areas, mainly aimed at ensuring the effective functioning of the electrical complex with an electric motor load. In the course of the study, a detailed assessment and analysis of the degree of influence of the asymmetry of the supply voltage on the operational reliability of low-voltage asynchronous electric motors was carried out. The results of the study were discussed, recommendations for the use of asynchronous electric motors in the presence of asymmetry of the supply voltage were formulated.

THE PURPOSE. Investigation of the operating modes of an isolated power supply system with controlled distributed generation plants, energy storage units and a drive load. Determination of the influence of the proposed prognostic controller of a distributed generation plant on the control parameters and quality indicators of the control process under various operating modes of an isolated power supply system.METHODS. The studies were carried out on a computer model of an isolated power supply system of an industrial enterprise with a turbine generator plant, a wind generator plant and a high-power electric storage unit, for which a fuzzy control system and a prognostic controller were used. The simulation was performed in MATLAB using Simulink and SimPowerSystems packages.RESULTS. The article describes a computer model of an isolated power supply system, as well as a structural diagram of the proposed autoprognostic speed controller. The simulation results showed that the combined use of an energy storage unit and an auto-prognostic generator rotor speed controller makes it possible to ensure the stability and survivability of an isolated power supply system, increasing its damping properties. The use of a fuzzy control system of a wind-generating plant made it possible to ensure its stable operation in all considered modes.CONCLUSION. The auto-prognostic speed controller, which does not require special settings, and the energy storage unit provide high quality control indicators in normal and emergency modes. It is advisable to conduct further studies to coordinate the actions of the control system of the electric energy storage unit and the auto-prognostic speed controller of the distributed generation plant.

THE PURPOSE. The main purpose of the work is a comprehensive study of external influences that affect the operational reliability of low-voltage asynchronous motors. Attention is focused on the evaluation of the operational reliability of electric motors, the systematization of their operating conditions, with the simultaneous impact of a group of operational factors. Among these factors that are subject to detailed analysis, we will highlight the following: the asymmetry of the stress and its duration, loading of the motor, the temperature of the environment. In this regard, it becomes obvious that the task of improving the operational reliability of low-voltage asynchronous electric motors depends on a qualitative study of the quantitative values of external influencing factors in various operating modes of electric motors. METHODS. The tool for implementing this task is a visual and effective simulation tool Simulink interactive programming environment Matlab. RESULTS. The research was performed on an asynchronous electric motor with a short-circuited rotor AIR160S8 with PH = 7,5 kW, rated speed n = 1500 rpm. The physical processes of the electric motor under study were modeled by changing the following parameters: the coefficient of stress asymmetry in the reverse sequence (K2U), the load on the motor shaft (Kz), the ambient temperature (tocr), and the duration of stress asymmetry in the reverse sequence (T). Based on the obtained simulation results, groups of planes of the studied quantities are constructed. CONCLUSION. A set of studies performed using the Matlab software package allowed us to estimate the limits of acceptable values of external factors and identify the area of acceptable operation of asynchronous motors. The analysis and discussion of the research results were carried out, and measures were proposed to improve the operational reliability of asynchronous electric motors.

The development of the modern world directly depends on the development of transport infrastructure. One of the types of transportation is the pipeline system, they are designed mainly for the delivery of liquid from one region to another, the most popular pipelines are oil pipelines and gas pipelines. Water pipelines are usually located in densely populated areas, while oil pipelines are often located in hard-to-reach areas, for example, in the regions of the Far North. As a rule, such territories do not have a centralized power supply, which creates additional difficulties in ensuring their functioning. Generally, diesel generators are the source of electricity in such regions. Based on the analysis of the oil transportation cycle, the authors proposed a certain way to increase its energy efficiency and increase reliability. The aim of this work is increasing energy efficiency and reliability of electrical equipment for own needs in oil pipelines. To achieve this goal, it is proposed to replace diesel generators with plants using renewable energy sources. In particular, it is proposed to use wind-solar installations. These installations are supposed to be used as the main power sources, while diesel generators will be used as stand-by sources of energy. The article provides a feasibility study for this event, as well as specific technical solutions for its implementation. First of all, this event will reduce fuel costs. Also, this will increase the category of reliability of the emergency valve from the third to the first.

One of the most important properties of the electric power system is its observability. Ensuring observability is relevant not only for power flows and reliability indicators of power supply, but also for power quality indicators, in particular, the non-sinusoidal shape of the supply voltage. Increasingly, the use of elements of power electronics in intelligent power systems, and its application will grow in the future. This leads to the appearance of harmonic components of higher orders of current and voltage. The objects of the power system can be either sources or receivers of harmonics. In this regard, the actual task is to assess the impact of individual objects on the quality of electrical energy in the power system. The observability of Проблемы энергетики, 2017, том 19, № 7-8 86 power systems can be realized by the application of the phasor measurement units (PMU). In this paper, the authors suggest using a distributed system for monitoring the power quality by using the existing PMU infrastructure. This will allow for continuous monitoring of the level of harmonic oscillations in different sections of the power system. Especially this event should be used for isolated power supply systems.

It proposed a two-way method of determining the place of the short circuit in the power lines, using the instantaneous values of currents and voltages. This sampling interval is proposed equal to a quarter period of the mains frequency. With this range are excluded even harmonics and odd harmonics are calculated without distortion. Given that zero components in the currents and voltages can be eliminated schematics, low-pass filters can be performed with a cutoff frequency of 250 - 300 Hz. To determine the fault location is proposed to use the parameters of the direct and reverse sequences.