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The main objectives of this publication are: 1) to attract the attention of energy specialists to the problems of reliability and electrical safety of 6-10 kV overhead electrical networks with isolated neutral, operating in conditions of single-phase insulation damage; 2) substantiation of the feasibility of introducing a fundamentally new way to improve the efficiency of 6-10 kV distribution networks, based on the resonanceless limitation of the single-phase ground fault current arising from the breakdown of the insulator and the use of its own infrastructure of the electrical network for remote identification of the place of its occurrence. The expediency of including a nonlinear surge suppressor between the traverse and the grounding outlet of the reinforced concrete support is confirmed by the positive results of experimental studies carried out on the basis of high-voltage testing laboratories of IDGC of Center PJSC - Orelenergo and EnerGarant LLC. The use of deductive analysis allowed the authors to select a reliable and affordable electrical insulating material installed between the support and the traverse, as well as to formulate the main requirements for it, including taking into account weather and climatic factors. The analysis of various methods of transmitting information about the place of occurrence of the insulator damage made it possible to establish the predominant advantage of a wired communication channel using its own 6-10 kV electric network infrastructure. The authors have developed an original circuitry solution that provides remote identification of the insulator damage location using a thyristor shunting the nonlinear surge suppressor, according to a given switching algorithm, and also provides local identification of the insulator breakdown by means of special signaling devices with volatile power supply. It is expected that the proposed method, with relatively low investment, will significantly reduce the level of accidents and electrical hazards in overhead distribution networks of 6-10 kV, as well as minimize the costs associated with their operation and undersupply of electrical energy.

The electric power industry cannot develop without analyzing the factors that affect the shape of currents and voltages when determining the parameters of the electric network mode in the context of the introduction of modern means of intellectualization into the structure of power supply systems. The share of equipment affecting the electric power quality reaches 90% in modern electrical networks. This leads to the appearance of noise in the network that reduces the quality of electrical energy, voltage distortion by higher harmonic components in particular, and affects the adequacy of the parameters of the electrical network adopted by automatic control devices. The article presents the results of digital signal processing containing distortions in the form of a harmonic component with a decrease in the sampling frequency. It is shown that a decrease in the sampling frequency does not exclude the effect of higher harmonics on the result of processing signals, including high-frequency distortions.

One of the most important areas is to ensure the required reliability of power supply to coal mining enterprises. This problem is associated with the high hazard due to accidents at coal mines. The article discusses approaches to solving the problem of finding the best ways to improve the efficiency of the external power supply system. This makes it possible to increase the reliability of power supply to the coal mines of the Kemerovo region – Kuzbass. On the basis of the information method, an algorithm has been developed that makes it possible to take into account the topology of the electrical network, increasing its reliability. Measures to improve the external power supply of LLC “Mine“ Pervomayskaya” are proposed and substantiated. A feasibility study for the direction of increasing the stability of the structure of the electrical network is presented.

The parameters of electrical network modes do not correspond the requirements GOST 32144-2013 of Russian and the National technical regulation of Vietnam. In real operating conditions in electrical networks in non-sinusoidal and unbalanced modes there are harmonic components of voltages and currents as well as voltages and currents of negative sequence. They cause additional losses of active power, which leads to additional heating and causes premature aging of the insulation, and as the result, the reduction in the service life of induction motors. Currently, we see that the process of formation of intelligent electrical power systems is underway. Systems for continuous monitoring of power quality indices and parameters of electrical systems modes are being developed. These systems can be supplemented with programs for calculating characteristics that issue the warning when the unfavorable influence of the parameters of non-sinusoidal and unbalanced modes is detected on various electrical equipment of both electrical power systems and consumers of electrical energy. The paper provides an overview of the characteristics used to analyze, assess and predict the influence of poor power quality associated with non-sinusoidal and unbalanced of currents and voltages on induction motors. A computer program was developed to calculate these characteristics. The program was used to study the influence of non-sinusoidal and unbalanced modes on the induction motors of the coal sorting plant of the Vietnamese company “Cua Ong-Vinacomin”.

Modern trends in the development of the electric power industry declare the widespread use of information and communication technologies and digital services to improve the operation of relay protection and automation (RPA) subsystems, Industrial Control Systems (ICS), commercial electricity metering systems, etc. However, it is associated with an increase in the number of cyber threats and risks of disrupting the stable functioning of electric power facilities due to destructive information influences. The report presents aspects of a holistic concept of building cyber-protected digital substations with elements of Zero Trust Architecture. Based on the results of the theoretical investigation the authors assume the possibility of technical testing of the proposed approaches to build a cyber-protected digital substation as a part of the emerging Research and Development (R&D) programs for the practical implementation of the zero-trust policy.

The introduction of “smart grids” technologies poses the problems of multi-criteria determination of the optimum voltage in the main substation of the object under study. In this study the busbar sections of the field substation of the oil and gas company is considered as the main substation. This paper studies regulation of voltage level in an electrical network using on-load tap changer (OLTC) of a power transformer for field substation of an oil and gas enterprise. Considered are approaches for voltage regulation taking into account the development of smart grid technologies. The authors have developed a universal method for determining the optimal voltage level on the busbar sections of a field substation, which allows for selection of the optimum voltage in accordance with certain parameters: loss of active, reactive power, voltage, electricity consumption, specific consumption or efficiency factor of artificial oil lift. The actual daily graphs of consumption of active, reactive power and voltage level at one of the field substations of PJSC Tatneft were studied. The operation mode of on-load tap-changer drive of the field transformer was modeled, taking into account the calculated optimal values of voltage and the dead zone. The paper presents the results of study of automatic voltage regulation on busbar sections of a field substation, taking into account the constraints for tap changer switches of a power transformer.

The paper proposes a concept of building a digital twin based on the reinforcement learning method. This concept allows implementing an accurate digital model of an electrical network with bidirectional automatic data exchange, used for modeling, optimization, and control. The core of such a model is an agent (potential digital twin). The agent, while constantly interacting with a physical object (electrical grid), searches for an optimal strategy for active network management, which involves short-term strategies capable of controlling the power supplied by generators and/ or consumed by the load to avoid overload or voltage problems. Such an agent can verify its training with the initial default policy, which can be considered as a teacher’s advice. The effectiveness of this approach is demonstrated on a test 77-node scheme and a real 17-node network diagram of the Akademgorodok microdistrict (Irkutsk) according to the data from smart electricity meters.

This article provides a brief overview of the existing problems of managing the electric power system, taking into account the sources of distributed generation. The features of centralized and decentralized power supply systems are considered from the point of view of changing operating conditions, in particular, eliminating the consequences of technological violations. The main goals of the electric power system management have been determined, regardless of the number of sources and the category of consumers in terms of power supply reliability, as well as in emergency and post-emergency modes. The basic principles and sequence of power system management are presented. An algorithm for the efficiency of operation and dispatch control of the power system is considered, methods for ensuring the selective operation of relay protection and automation devices in the presence of several generating capacities are presented. A fragment of an electrical network with four energy sources is shown and the main measures to ensure its normal functioning are proposed.

In the work experimental studies of the developed method for determining the insulation parameters in an asymmetric electrical network by a voltage up to 1000 V at mining enterprises were carried out. It is based on measuring the module values of line voltage, angle of phase shift between vectors of damaged phase voltage relative to the ground and line voltage at two other phases, as well on measuring the module value of damaged phase voltage relative to the ground before and after connecting additional capacitive conductivity between the network’s phases and the ground. The results of experiment showed that the developed method for determining the insulation parameters has satisfactory accuracy and safety when operating three-phase electrical networks by voltage up to 1000 V at mining enterprises.

It is known that the occurrence and existence of ferroresonant oscillations at the subharmonic frequency (SHC) in power transmission lines (TL) and in power supply systems is extremely undesirable, since they cause ferroresonant overvoltages at different frequencies. At the same time, there is a wide class of nonlinear electrical circuits, in which the excitation of autoparametric oscillations (AIC) at the frequency of the SHC forms the basis of frequency converting devices serving as secondary power sources. It is shown that three-phase nonlinear systems are in one way or another equivalent circuits for power transmission lines, the main elements of which are: longitudinal compensation capacitors, transverse compensation reactors, and transformers with a nonlinear characteristic. To study the regularities of the excitation and maintenance of SHC at a frequency in three-phase electro-ferromagnetic circuits (EFMC), theoretical and experimental studies of an equivalent model of a three-phase circuit with nonlinear inductance were carried out. For the analysis of the steady-state mode of the SHC at the frequency, the method of a small parameter (averaging) was applied. A shortened differential equation of motion for a three-phase nonlinear circuit is obtained. By solving them, the regions of existence of the SHC and the critical parameters of the chain were determined. The obtained results of theoretical research are confirmed by experimental studies.

The paper considers the possibility of modeling the process of controlling the power supply of the consumer in the lower levels of network organizations to improve the quality indicators of electrical energy in the distribution electrical networks of 0.4 kV. The analysis of the process of control of indicators of the quality of electricity in the supply of energy to consumers. The block diagram of the adaptive power supply control module of the consumer and the algorithm of the control process are presented. A consumer power supply control module in 0.4 kV distribution networks is proposed.

A systematic approach to determining the control range of the on-load tap-changer of transformers from the standpoint of the synthesis of the voltage mode is proposed. Transformations of the equation of nodal voltages, formalized on the basis of the topology of a complex electrical network, with respect to the transformation ratios of transformers are given.

The problem of detecting changes in a topology of an electrical network in real time is solved. This paper proposes a line state detection method based on a convolutional neural network (CNN) classifier using phasor measurements of bus voltages and currents in transient states.

This article discusses the use of special software products for the design and simulation of the operation of electrical circuits, namely, the most commonly used programs Electronic Workbench and Multisim are compared, their advantages and disadvantages are determined. In the course of the experiments, on the basis of the above presented software systems, the operation of the electrical circuits of the devices of the amplitude diode detector and the low-frequency amplifier was simulated to identify the capabilities of the programs. In the course of the research, a visual table was compiled, thanks to which it is possible to compare the obtained parameters with the reference characteristics taken from real-life devices. The uptime was chosen as a control parameter, the article contains its calculation formula, and the final calculations are given in the table to better substantiate the capabilities of the software products under consideration. At the end of the article, conclusions are presented on the work done, thanks to which it is possible to determine the pros and cons of each of the programs under consideration.

The wide use of distributed generation (DG) technologies in electrical energy systems (EES) requires development of new control algorithms in normal, emergency and postemergency modes. The issues of determining the static aperiodic stability (SAS) margin in EES equipped with DG plants are of particular relevance. These plants can be removed from the consumption centers, which can lead to SAS reserves depletion. The article presents the results of studies aimed at the developing SAS reserves express calculation methods in EES equipped with DG plants. An effective technique to determine stability margins was proposed based on one of the modifications of limiting modes equations. The results of determining SAS for an electrical network with distributed generation plants are presented. Additionally, the simulation of transient processes in the studied EES for various points in the space of the mode’s controlled parameters has been carried out in the Matlab system.

The article discusses distribution electrical networks 0.38 kV operating modes, feeding individual residential buildings. The electrical energy parameters measurement were certified RESURS-UF2M device carried out. The currents and voltages time diagrams based on the measurements made and using Matlab technologies were constructed. It is established that the level of phase currents unbalance is quite high and causes significant three-phase power supply system unbalance voltage accordingly. The power of quality indicators - calculations, characterizing voltage unbalance were made, which were based on the measurements and the computer program “Asymmetry” was used. As well as the additional power losses coefficient determining by the phase currents unbalance, were calculations. Time diagrams these indicators are constructed and their analysis were made. As a result, the power of quality is significantly reduced by unbalance power consumption in the studied electrical network were founded. At the same time, the additional power losses are significant increases. Specific recommendations for the normalization electrical network-operating mode are given.

Violation of the symmetrical mode of operation of the electric network causes a deterioration in the quality of electric energy and significantly reduces the reliability of the functioning of electrical equipment and elements of the electric network. A mathematical model of an electrical network with a grounded neutral is proposed аnd a software package that allows us to evaluate the level of voltage asymmetry of a three-phase system depending on the changing unbalanced load was created. The simulation and calculation of the studied parameters for various combinations of loads and the technical means of balancing the operating mode of the electric network (the balancing device – BD) is carried out. Programs for the Matlab graphic editor are compiled and diagrams of changes in electricity quality indicators are constructed. A numerical analysis is carried out and recommendations are given to determine the most appropriate place for connecting the BD in the electrical network to improve the quality of electricity based on the calculation made.

Congestion caused in the electrical network due to renewable generation can be effectively managed by integrating electric and thermal infrastructures, the latter being represented by large scale District Heating (DH) networks, often fed by large combined heat and power (CHP) plants. The CHP plants could further improve the profit margin of district heating multi-utilities by selling electricity in the power market by adjusting the ratio between generated heat and power. The latter is possible only for certain CHP plants, which allow decoupling the two commodities generation, namely the ones provided by two independent variables (degrees-of-freedom) or by integrating them with thermal energy storage and Power-to-Heat (P2H) units. CHP units can, therefore, help in the congestion management of the electricity network. A detailed mixed-integer linear programming (MILP) optimization model is introduced for solving the network-constrained unit commitment of integrated electric and thermal infrastructures. The developed model contains a detailed characterization of the useful effects of CHP units, i.e., heat and power, as a function of one and two independent variables. A lossless DC flow approximation models the electricity transmission network. The district heating model includes the use of gas boilers, electric boilers, and thermal energy storage. The conducted studies on IEEE 24 bus system highlight the importance of a comprehensive analysis of multi-energy systems to harness the flexibility derived from the joint operation of electric and heat sectors and managing congestion in the electrical network., Comment: Conference: 100% Renewable Applied Energy Symposium 2020, October 29-30, 2020

The aim of the work is to develop a device design for creating constant magnetic fields and select its parameters, select an electrical circuit for powering the device and determine how the energy efficiency of the device changes with an increase in its overall dimensions. When solving the problem, the KOMPAS-3D three-dimensional modeling system was used, the magnetic field induction was calculated using the Pascal ABC programming system, the optimal device parameters were selected using the Microsoft Excel program. Calculations have shown that the coefficient taking into account the inhomogeneous distribution of the magnetic field in the device is 0.883. The optimum ratio between the height and the radius of the cylinder, along which the emulsion flows, is h = r √ 20 hr. Using the KOMPAS-3D three-dimensional modeling system, a model of the device under development was built taking into account the obtained relationships. When using a circuit with an uncontrolled rectifier and autotransformer, the power consumed by the device is 2.67 times lower than the power consumed by the device when using a circuit with a controlled rectifier and a transformer. Energy efficiency increases significantly with the increase in device performance.

The paper discusses the influence of low-quality electricity on the temperature modes of operation of an asynchronous motor. In the course of experimental and analytical studies, the heat transfer coefficients and heat capacity of a particular electromechanical converter were determined. Experimental and analytical dependences of temperature changes of an asynchronous motor on time are given when it is connected to a supply voltage with different coefficients of sinusoidal distortion and negative sequence. The resulting model is tested for its adequacy to the real process and can be used as an element in the energy-economic model of an asynchronous motor to assess its uptime. This model that can be useful for simulation of thermal processes in asynchronous motors and optimising these devices for increasing the reliability.

With longitudinal compensation of the reactance of the line, the problem of its protection against overcurrents arises from the point of view of relay protection. The problem is relevant with a greater degree of compensation. When compensating more than 50% of the reactance of the line, the protection of the power transmission line becomes practically impossible due to the failure or false operation of all existing types and forms of protection [1, 2]. Therefore, at present, the compensation of the line reactance is, as a rule, no more than 50% [3, 4], which does not allow the full potential of the line in terms of its transmission capacity to be revealed. The purpose of this study was to develop and test a new relay protection algorithm to be able to solve the above problem. The studies were carried out using modeling techniques in the PS CAD package, where a power transmission line with longitudinal compensation and an algorithm to protect it from internal damage were built. When carrying out the research, the work was carried out on the protection algorithm of the power transmission line with longitudinal compensation in the static mode without transferring electricity between substations and without the transmission mode along the active power line in both directions. It is shown that in order to determine the location of the damage, it is possible to use the criterion of the angle of the active component of the short-circuit current, which depends exclusively on the voltage angle and does not depend on the reactive parameters of the electrical network. The simulation result showed correct operation in all investigated modes. The algorithm described in the article showed quite satisfactory results, which makes it possible to protect the power transmission line with any degree of longitudinal compensation.

Poor power quality creates big problems. With the poor power quality, the service life of the equipment is reduced. In connection with the creation and development of intelligent electrical power systems and the digital economy, the requirements for the power quality are increasing. Active harmonic filters began to used to solve problem with the poor power quality. The paper presents a methodical approach and computer programs for determining the power of the active harmonic filter. The power supply system of the Vietnamese coal sorting plant is considered to develop the methodical approach. The results of measurements of the power quality indices and the results of calculating the parameters of the modes of the electrical network of the plant at the fundamental frequency were used. To process a large amount of measured information, the special computer program was developed. On the basis of the methodical approach, the results of measurements of the power quality indices and the computer complex “Stationary permissible optimal mode”, the algorithm and the computer program have been developed to calculate the power of the active harmonic filter. The power of the active harmonic filter for the coal sorting plant was determined with the help of this program.

The parameters of electrical network modes often do not meet the requirements of Russian GOST 32144-2013 and the guidelines of Vietnam. In the actual operating conditions while there is the non-sinusoidal mode in electrical networks voltage and current harmonics are present. Harmonics result in overheating and damage of power transformers since they cause additional active power losses. Additional losses lead to the additional heat release, accelerating the process of insulating paper, transformer oil and magnetic structure deterioration consequently shortening the service life of a power transformer. In this regard there arises a need to develop certain scientific methods that would help demonstrate that low power quality, for instance could lead to a decrease in the electrical equipment service life. Currently we see a development of automated systems for continuous monitoring of power quality indices and mode parameters of electrical networks. These systems could be supplemented by characteristics calculating programs that give out a warning upon detection of the adverse influence of voltage and current harmonics on various electrical equipment of both electric power providers and electric power consumers. A software program presented in the article may be used to predict the influence of voltage and current harmonics on power transformers.

This paper discusses the wound rotor induction motor and variable-frequency drive (VFD) that regulates the stator voltage frequency. The stator and rotor windings are connected to a common electrical circuit. The slip energy of the motor goes to the DC link and feeds the stator winding of the motor. The block diagram of the electric drive, the equivalent circuit and the basic characteristic of the cascade VFD are considered. It is shown that the energy-saving mode with a minimum ratio “stator current/torque” is achieved at an angle between vectors of the stator current and the excitation current at the level of 45 degrees. The experimental static mechanical characteristics of the electric drive were obtained. These characteristics provide a limitation of the starting torque.

One of the quickly developing trends in the optimization of electric power grids is system development of operation and optimization of branch circuits which are based on linear programming problems. One of its categories is traffic problem. The paper discusses the formulation of various types of transport optimization problems used in the design of the most efficient power supply systems in the real sector of economy. The construction of arithmetic models of problems is carried out. Their optimality criterion is cost minimization for the design of electrical network diagrams consisting of power lines connecting sources and consumers. Examples of designing optimization power layout in mathematical problems considering the transmission capacity of power lines is given. The paper also touches upon a mathematical problem considering possible transit of capacities. The task is to build a mathematical model and solve problems that ensure minimization of process losses and losses of power when designing electrical networks. The results of solving problems are presented in the form of power supply circuits corresponding to the most optimal linking of source and consumer nodes. The work is of a scientific and practical significance as it considers the problem of optimizing economic costs when designing electric power network schemes. Moreover it is based on a qualitatively different level of use of the traffic problem algorithm. The algorithm for solving the minimization problem obtained in this paper allows developing the necessary computing operations as well as quickly obtaining the results of solving the cost optimization problem in the designed electric power network.

An object of research is a diesel power supply system of the decentralized village of Tokma, Irkutsk Region, Russia. The objective is to increase the contribution of the PV part of a photo-diesel electrical system operating in parallel with a diesel power plant to a stand-alone distribution network of DC compared to parallel PV and diesel stations operating on AC; quality improvement and voltage stabilization in the electrical network; cost reduction of generated electricity. Optimization of the characteristics of a stand-alone power supply system at a DC is a difficult task, due to the impossibility of conducting tests in a real electric power system, and the use of physical modeling because of its extreme complexity. Given this fact, the task is to design software and hardware tools for optimizing the parameters of a DC photo-diesel power system. The developed models use MS Excel, MatLab/Simulink software packages, as well as weather data bases. A software tool has been developed that allows for simulation modeling of operating modes of photo-diesel power supply systems, generation, consumption and insolation level of a decentralized consumer, as well as determining rational technical and economic parameters; criteria of expediency and efficiency of constructing photo-diesel electric systems with DC have been identified. As a result, the level of voltage drop is reduced compared to the AC power supply system, the cost of 1 kWh of electrical energy is lower than in the AC power supply system, and the negative environmental impact is reduced.

The electrical equipment operation is cost-effective and reliable when operating parameters of the electrical network correspond to the rated data of the equipment. The real operation conditions, however, differ from those required for electrical equipment, which negatively affects its efficiency. The non-sinusoidal conditions in electrical networks are currently very common. The paper provides an overview of the characteristics obtained from an analysis of publications, which are used to evaluate the effect of the non-sinusoidal conditions on power transformers. The results of the calculation of these characteristics for a transformer installed at a railway traction substation are presented. Parameters of the non-sinusoidal conditions are obtained as a result of measurements.

Classical methods for modeling the steady-state modes of complex electrical networks and systems are based on the application of nonlinear node equations. Nonlinear equations are solved by iterative methods, which are connected by known difficulties. To a certain extent, these difficulties can be weakened by applying topological methods. In this paper, we outline the theoretical foundations for the formation of the inverse form of nodal stress equations based on the topology of electrical networks and systems. A new topological method for calculating the distribution coefficients of node currents is proposed based on all possible trees of a directed graph of a complex electrical network. A complex program for calculating current distribution coefficients and forming steady-state parameters in the MATLAB environment has been developed.

Nowadays, a strong link exists between human comfort and electrical power. Abundant doings are not possible without the support of the electrical energy. Driven by the human obligation to save the environment, the installation of PV solar system increased dramatically in the past numerous years. The installation can be grid connected or standalone system. These micro-grid situations are installed world-wide and currently are contributing to the local electrical network. To maximize the use of the generated solar system, numerous system installed energy storage in the form of batteries. These energy storages harvest the sun power during daylight to support the household electrical demand after sunset. This paper linked the house roof design to the PV solar system for maximum generation condition. Furthermore the paper contains important information on the optimum location for the solar panel to ensure continuous and reliable system is achieved. An actual real case study is presented.

The article is devoted to the electrical energy measurements estimates calculation. Automatic Meter Reading systems are the source of measurements. Two methods are compared. The first one is based on the energy flow problem, which allows to receive the estimates of the electrical energy flows and losses on all elements of the electrical network. Calculations using the first method were made using the software product "Balance". The second technique is simplified and uses a system of testing equations to calculate the measurements estimates. Comparison showed the use of a simplified procedure gives adequate accuracy on condition of sufficient redundancy level. © 2018 The Authors, published by EDP Sciences. The reported study was funded by the Ministry of Education and Science of the Russian Federation under Federal Targeted Programme according to the agreement № 14.578.21.0226 (Project identifier: RFMEFI57817X0226).

This paper proposes how using electric storage heaters could provide a portion of the system reserve requirements which would otherwise have to be satisfied by conventional generation. With the upgrade and install of new advanced electrical storage heaters there is the potential to provide large system reserve capabilities when combined with a high-speed communications network. Together with these new more efficient heaters, not only will domestic emissions be reduced, the overall electrical grid CO2 intensity should experience an improvement due to the incorporation of the demand side management (DSM) aspect. The All-Ireland system has been used in this paper as an example of an electrical network which is undergoing a significant transition to high penetrations of renewables, while having a considerable population of potentially upgradeable electric heating sources for DSM control.

This scientific article is devoted to one of the priority issues in electronics, namely the implementation of the engineering task of designing a power source. In my case, according to the terms of reference, which includes: the main parameters of the network, efficiency, a structural electrical circuit of a switching power supply was developed. In the process, the main functional units (blocks) were calculated and the choice of radio components from which they were built on the basis of: current values, reverse voltage, gain, operating frequency and other parameters of diodes, transistors, integrated circuits, Zener diodes, operational amplifiers was justified. In the “Methods” section, calculations will be made for the device blocks: a network rectifier, a push-pull transformer converter, a pre-amplifier circuit with a transformer input, an error signal comparison and amplification circuit, a sawtooth voltage generator, and a secondary power source. The information presented in the text is recommended to a narrow circle of specialists, priority in the field of power electronics, as well as in the field of communication systems.

The paper gives a method of accounting the dynamics of technological connections when forming a list of objects for the reconstruction and construction of electrical networks. The specified method allows maintaining a database of technological connections taking into account the information received from the monitoring systems for electric network operating modes. It makes it possible to assess the dynamics of technological connections by settlements and regions. Based on this, it allows determining the availability of a power reserve for new technological connections and pre-compile a list of objects for reconstruction and construction of electrical network taking into account the dynamics of technological connections.

Sustainable operation of the power grid complex is impossible without reliable and high-quality operation of 10/0.4 kV electrical distribution networks, which are the final link in the system for providing consumers with electric energy and are in direct interaction with a specific consumer. The study of statistical information on the composition of distribution networks makes it possible to draw conclusions about electrical network state, to implement recommendations for their development and to compare distribution electrical networks in different regions. This information is especially relevant for analyzing the reliability of power supply to consumers connected to the considered electrical distribution networks. Such indicators of network structure as the length of electric transmission lines of different voltages and power transmission schemes are studied. It also analyzes the number of damages in networks, the causes of these damages, data on the time of planned and emergency outages. This paper considers the structure of 10/0.4 kV electrical distribution networks located on the territory of one of the districts of the Kaluga region. The sample for distribution networks was: 1190 overhead transmission lines and 536 transformer substations. Consumers in the district are 21671 subscribers of individuals and 1986 subscribers of legal entities, that is, a total of 23657 metering points. On the lines of 0.4 kV and 10 kV, the percentage of their isolated design was revealed. The share of single-transformer and two-transformer versions of transformer substations is analyzed.

Possible cases of non-fulfilment of the requirements of the necessary sensitivity and the selectivity of the existing protection against incomplete-phase and asymmetric modes in the electrical network under conditions of uncertainty of the initial data are determined. The paper considers the issue of intellectualization of protection from asymmetric modes based on theories of fuzzy logic, as well as machine learning models, and offers a structural diagram and an algorithm for the functioning of protection. The results of the synthesis of intelligent protection and an approach to modelling and control for controlled drive systems based on reinforcement learning are presented.

Many scholars have been focusing on the energy management by Integrating a smart grid into a conventional electrical grid. They have showed that to meet a certain power demand of the consumers, using energy management, the electric utility can turn on some generators, which may have the least operation cost, while the generators with high operation cost are left to supply extra load demand in specific peak periods. Henceforth, the operation cost of its generation units is minimized. The issue remains at a level of relating the energy management to CO2 emission. The present paper briefly discusses the Rwandan electrical network that still integrates the use of diesel generators. It estimates the amount of CO2 emission that can be avoided once a PV system is integrated into the electrical network. The paper as well proposes an algorithm for energy management with consideration of CO2 emission.

This article describes the features of voltage regulation in electrical networks of 35, 110, 220 kV. The structural diagram of the 35/10/0.4 kV network is presented. The paper also describes the adaptive automatic voltage regulation system which allows regulating the voltage taking into account the actual voltage values at the consumers’ inputs. The structural diagram of the adaptive automatic voltage regulation system in the 0.4 kV electrical network using a boost transformer as an additional means of voltage regulation is given. The system is based on voltage sensors installed in different parts of an eletcrical network sending information on voltage values to to the processing unit which generates a signal for voltage regulating supplied to the executive device and the working body whuch, in turn, change the on-load tap-changer position of a transformer. The paper justifies the need for the enhancement of the adaptive automatic voltage regulation system for different voltage classes wich allows controlling a voltage change at different power supply system levels and regulating voltage level in accordance with this change. For this problem the multi-level adaptive automatic voltage regulation systemis proposed. The system allows regulating the voltage not only in the 0.4 kV network but also in networks of higher voltage classes. The proposed system can be integrated into the structure of intelligent electrical networks.

Numerous studies of various physical factors show the promise of using pulsed magnetic fields in bioregulatory technologies to stimulate plant life and growth processes. As a result of exposure to garden strawberries with a low-frequency magnetic field, the quality of planting material improves, plant immunity increases, crop growth and development accelerates, the number and weight of berries increase. The article presents a developed automated device for magnetic pulse processing (MPP) of plants, considers the device, design and principle of its operation. The electrical circuit of the device and its technical characteristics are given. According to the results of a laboratory experiment, the magnetic field parameters of the working body of the device in the near zone of a flat spiral coil were established. The numerical value of the magnetic induction at a distance of 100 mm from the center of the coil is 8.3 mT.

Photovoltaic power station (PPS) operating function (without redundancy) with a nominal capacity of 10 kW connected to the low voltage electrical network established by "Zhejiang Chint Electrics Co Ltd" (PRC) under Tashkent conditions is defined. Operation parameters and characteristics of the PPS and parameters at the output of the network inverter are given. The deviations of voltage of each phase from the standard nominal voltage at the point of electric network transmission are studied. The analysis of the results of the evaluation of the power generation of the PPS for the conditions of clear weather and clear cloudiness was carried out. According to the monitoring data for the winter period is 2211,5 kW·h. The problems of PPS connected to the low-voltage network, connected to the loss of electric power with the account of influence of external factors and reliability of stable voltage and frequency in a permissible range are revealed.

The exploitation of cyclostationarity properties of vibratory signals is now more widely used for monitoring rotating machinery and especially for diagnosing bearing defects. The acoustic emission (AE) technology has also emerged as a reliable tool for preventive maintenance of rotating machines. In this study, we propose an experimental study that characterizes the cyclostationary aspect of acoustic emission (AE) signals recorded from a defective bearing (40 μ m on the outer race) to see its efficiency to detect a defect at its very early stage of degradation. An industrial sensor (UE10 000) is used. An electrical circuit converts the high frequency signal into an audible signal by heterodyning. The cyclic spectral density, which is a tool dedicated that put into evidence the presence of cyclostationarity, is used for characterizing the cyclostationary. Two new indicators based on this cyclostationary technique are proposed and compared for early detection of defective bearings.

The steadiness over time, of on-board Energy Storage Systems (ESS) performances is a major issue fora successful and massive diffusion of electrified, hybrid and electric vehicles. Capacity fade and internal resistance increase due to ageing will directly affect vehicle range and performances. Therefore, ESS ageing forecasting remains an important area of investigations. Reaching this goal involves fundamental research on materials, experimentation, simulation and design by the end users. This paper describes the main results of a 3.5-year, 4.2 M€ collaborative research program on battery ageing, SIMSTOCK, which was finished in fall 2011. This program has involved 15 partners among which, research labs, ESS manufacturers, automotive components suppliers and vehicle manufacturers, with the support of the French agency ADEME.This paper will then focus mainly on modeling and simulation of a lithium-ion high power cell tested within the program. First, it describes the development of a numerical equivalent electrical circuit model of battery, associated with a calibration tool and its experimental validation. Secondly, it describes the construction of a Design of Experiments (DOE), its use and validation, for defining mathematical expressions, representing the battery model parameters evolutions, as a function of battery ageing. Thirdly, the paper details a mathematical method created with the aim to take into account the cycling and the calendar effects on battery characteristics during the experiment on tests benches. Finally, the battery model is integrated in a full hybrid vehicle model, on Imagine Lab AMESim simulation platform, to determine, with realistic driving conditions, the impact of battery ageing on the vehicle performance and fuel consumption.

In the practice by microwave power transistor amplifiers developing, the variable load method is usually used to determine the impedances of matching circuits in the complex conjugate matching mode. This solution involves the use of expensive equipment - coaxial impedance tuners and contact devices for mounting transistors in low impedance strip lines. An even more complicated and expensive way is the concept of X- parameters, based on the use of unique measuring equipment - a non-linear vector network analyzer, and a simulator for non-linear circuits design. The article proposes an alternative solution adapted to the operation of the transistor in real conditions and allowing to design the output stages of microwave power amplifiers using analysis and optimization of linear electrical circuits. The essence of the proposed solution is to automate the measurement of non-linear S-parameters of high-power microwave transistors in a contact device with tunable strip matching circuits for various DC supply voltage, frequency and input power mode in case of continuous or pulse input signal. The nonlinear S-parameters of the contact device are measured using the method of spatially remote variable load in the frequency range, in which the line conditioning and the maximum output power are achieved. The minimum of the reflected wave amplitude and the maximum gain are reached using movable strip matching transformers. The S-parameters measured in the coaxial line are automatically recalculated to the physical boundaries of the transistor by registering the positions of the input and output strip transformers.

Based on the results of the analysis of resistive circuits, a new circuit of an optoelectronic contactless voltage relay is developed in the article and its application in the power supply system is considered. The possibility of controlling the operating modes of various installations for amplifying electrical signals using optothyristors is presented and methods for their inclusion in electrical circuits are given. Optoelectronic contactless voltage relays were tested under laboratory conditions to obtain input-output characteristics and capacitance voltage waveforms. Based on the improvement of the proposed circuit, a circuit of an optoelectronic contactless voltage relay is developed and provides a high degree of reliability. The proposed voltage relay circuit is simulated using the Electronics Workbench and MATLAB R2014a programs, the results of which show that the changes in the shape of the output voltage curve are close to a sinusoid and coincide with the results obtained analytically.

The solution of the problem of a topology detection of an electrical network on changing voltage and current phasors obtained from the phasor measurement units (PMUs) in a transient state using artificial neural networks (ANNs) is considered. Experimental results for the 14-bus test system to detect the failed line after short circuit and the line was turned on by an auto-reclosing device are presented.

One of the main causes of the high accidents and outages rate in 6(10)-kV distributed power supply systems of oil well clusters is damage to overhead power lines due to single line-to-ground faults. Widely conducted studies to locate a single line-to-ground fault have established a correlation between the accuracy of determination and a large number of changing factors, such as operating mode parameters, overhead power line parameters, type of damage, transition resistance, soil resistance, and others. Rationing of technical means for determining the location of a single line-to-ground fault by instrumental errors without taking into account the methodological component translates into the error in locating the damage up to 30%. Thus, relevant research is aimed at determining the primary parameters of power lines and minimizing the methodological error in determining the location of damaged power lines, considering climatic factors. The study takes into account the basic physical processes of propagation of an electromagnetic wave in the power line. The main principles of the theory of electrical circuits and the electromagnetic field and MATLAB Simulink package algorithms are used. As part of the study, a technique has been developed that allows determining the distance from 6(10)/0.4-kV substations to a single line-to-ground fault location in distribution networks of oil well clusters taking into account climatic factors. A simulation model of a 10-kV distribution network supplying oil well clusters was developed in MATLAB Simulink, taking into account the dependence of the primary power line parameters on climatic factors and soil resistivity.

In recent years, controlled shunt reactors (CSR) relevant to the class of FACTS facilities have been widely used to control voltage modes and reactive power flows in the high-voltage electrical network. The selection of location, as well as the definition of the law of CSR control in the conditions of stochastic variability of the operation mode of high-voltage power transmission, are associated with numerous technical and economic factors. At the same time, such constraint conditions as ease of use, performance efficiency, purpose and location in the system, as well as the period of commissioning should be taken into account. In the proposed procedure these factors are considered as fuzzy constraints. The procedure of CSR placement in the 330 kV electrical network of Azerenergy system for control of reactive power flows taking into account the mentioned fuzzy constraints is proposed. The obtained simulation results confirm the advantage of the proposed procedure.

Wind power constitutes a variable energy source that introduces unbalance in electrical network management because it cannot be programmed. Then, the possibility of storing wind energy becomes very important. The lack of control is a drawback that disappears when the combination of a wind farm (WF) and a battery energy storage system (BESS) is considered. In that case, the goal is to adjust the power plant output and the load requirements of electrical network, i.e., to contribute to system adequacy as much as possible. Considering the features of the problem, it can be defined as an optimization problem. Two algorithms are proposed to solve it: the primal dual algorithm and the Mehrotra predictor-corrector one. In both cases, the best solution of the proposed problem is reached in an efficient manner. The primal dual algorithm performs better in terms of time and the Mehrotra predictor-corrector one needs fewer iterations.

Global electricity companies have embarked on a transition to digital microprocessor devices. Digitalization penetrates every aspect of power industry, whether it is power generation, transmission or distribution. Being the most widespread, the distribution electrical networks are nevertheless the least digitalized. Some issues about them are still insufficiently studied. These are the collection of necessary information, adaptation methods, and the effect of the unrecognizability of some short circuits. This can be explained by improper placement of devices, which causes lack of data, which, in turn, leads to the failure of relay protection and emergency control systems of distribution electrical networks to provide selectivity. The paper proposes algorithms for placing measuring devices so that the information will be collected properly. Placement of the devices will allow adjusting the operating parameters of the relay protection and emergency control systems depending on changes in external weather conditions and load fluctuations in the network. We propose a technique for control of distribution network, taking into account the type of damage in case of emergency in real time, and a technique for placement of measuring devices and creation of an information communication network.

The increasing diffusion of power electronics in the electrical equipment induces harmonic perturbations which reduce the power quality of power systems. Moreover, the induction machine is widespread in the industrial applications and it is often supplied by speed drives which generate non sinusoidal voltages. In this context, this study deals with the frequential modelling of the induction machine in order to simulate the line current with its harmonic components. Some of the frequential models existing in the literature are presented and compared. Then a circuit model of the machine based on the superposition principle, an harmonic model, is proposed. The comparison of the simulation results with the experimental measurements allows electing the harmonic model associated to the identification test using a DC current as the most representative of the machine behaviour.