RELEVANCE. In the process of developing diagnostic devices for technical objects, it is often very useful to create computer models of how these objects function. An adequate and universal model, for instance, of an operating insulating structure on an overhead power line (OHL) support, can significantly reduce the resources and time required for field experiments and tests when developing its diagnostic devices. OBJECTIVE. To create a computer model of the operation of an insulating structure on an overhead power line (OHL) support and on a laboratory setup, with a set of electrical parameters and characteristics necessary for diagnosing its condition. The simulation tasks included determining the distributions of the electric field, voltages, and currents in the space surrounding the insulator, taking into account the object's geometry, including external structural elements. METHODS. To achieve the set objective, the finite element method and the COMSOL Multiphysics software were used. The validation of the developed models was carried out by comparing the simulation results with measurements of the electrical parameters and characteristics of insulators in analogous laboratory and OHL configurations. RESULTS. The simulation resulted in the creation of a model of the operation of a suspension polymer insulator on an OHL and in a laboratory. Its adequacy and universality were proven during laboratory and field tests using sensors based on the principle of capacitive coupling and leakage current measurement. During the validation of the laboratory model, the calculated leakage current value for a dry insulator agreed with the measured one, with a deviation of less than 5%. The selection of the capacitive sensor electrode size (20x20 cm²), based on the simulation results, was confirmed as correct during field tests of prototypes of the SKAT-DI online insulation monitoring system on a 110 kV OHL.

THE RELEVANCE of the research lies in the development of methods for analyzing high-viscosity oil, whose share in world reserves and production is continuously growing. Accurate rapid analysis of the composition of such oil is necessary to optimize its production, transportation, and selection of chemical additives that increase mobility. However, application of the classical Bouguer-Lambert-Baer (BLB) law is difficult due to strong scattering of radiation and nonlinearity of optical response caused by complex multicomponent structure of high viscosity oil. THE PURPOSE is to develop a modified model of BLB law that takes into account rheological properties, and light scattering by asphaltene-resinous aggregates, and propose new model linking effective absorption coefficient to structural parameters of oil. METHODS. To substantiate the effectiveness of ultrasonic treatment as a method for sample preparation to improve the linearity of an oil medium, we used theoretical modeling and mechanisms for ultrasonic processing and its effects on optical properties. RESULTS. We show that consideration of rheological properties and light scattering is essential for an adequate description of the transmission of infrared (IR) radiation through viscous oil. The proposed modification to the BLB law incorporates additional terms to account for optical density due to particle scattering. Ultrasonic treatment reduces viscosity and heterogeneity, improving the transmission of IR radiation, which justifies its effectiveness. CONCLUSION. Integrating rheological factors into the BLB model and using ultrasonic preparation improves the accuracy of IR analysis of viscous oils. This will make it possible to more reliably determine the functional composition of high-viscosity oils in order to solve problems of increasing oil recovery, optimizing processes, and pipeline transport safety. Ultrasonic treatment provides a non-reactive reduction in viscosity and scattering, making it a promising method for sample preparation for rapid analysis.

THE PURPOSE of this work is to study the dynamic processes in nonlinear resistive electrical circuits using the Lagrange method, to identify the features of their mathematical description and analysis of transient processes, as well as to improve the circuits of contactless switching devices. RESULTS. The article presents the results of a study of the dynamic process in a nonlinear resistive electrical circuit using the Lagrange method and describes the development of its mathematical model. In addition, based on the developed mathematical model, an analysis of the time-dependent variation of the voltage across the capacitance under different parameters was carried out. The results of the study indicate that by determining the exact value of the voltage across the capacitance, it is possible to effectively control both the control voltage of the thyristor and the charging-discharging process of the capacitor. Thus, it has been established that when the capacitor reaches the saturation point, a time delay is provided for contactless switching devices. CONCLUSION. As part of this study, a theoretical analysis and numerical calculations of dynamic processes in a nonlinear resistive electrical circuit were carried out. The application of the Lagrange method made it possible to obtain the solution of the differential equation of the electrical circuit, and this study, to a certain extent, contributes to the investigation of dynamic processes in nonlinear resistive circuits.

THE PURPOSE. To develop and investigate a computer model of a three-phase two-level current inverter based on IGBT transistors with integrated thermal models. To create a switching system for inverter power switches based on pulse-width modulation with selective harmonic elimination (PWM-SHE) to solve the problem of the negative impact of higher-order harmonics on the industrial power supply network. The aim is to develop an automatic control system that allows switching between operating modes without stopping the power unit. METHODS. A computer simulation model was built in the MATLAB Simulink software package to study the proposed control system for a three-phase two-level current inverter. Real IGBT transistors from the Infineon company catalog were used as controlled power switches. The Selective Harmonic Elimination (SHE) method was applied using the iterative Newton-Raphson algorithm to calculate optimal switching angles for power switches. The control system is based on a fuzzy logic controller that provides automatic switching between different inverter operating modes. RESULTS. A control system has been developed that ensures automatic switching between operating modes depending on the temperature state of the power switches, the load current value, and the rate of temperature change of transistors. The switching system allows switching between the standard six-step mode and PWM-SHE modes with elimination of the 5th, 7th, and 11th harmonics without stopping the power unit. Three control channels are used for switching: by transistor temperature, by the derivative of temperature over time (heating rate intensity), and by load current. The system allows operation without changing the characteristics of the inverter power section. CONCLUSION. The developed control system for a three-phase two-level current inverter effectively solves the problem of the negative impact of harmonics on the power supply network using the SHE method. The system provides overload protection by automatically reducing the switching frequency when the temperature of the power switches increases, which prevents overheating of transistors and increases the service life of the power converter. The practical significance lies in the possibility of applying the developed system at industrial enterprises to improve power quality without additional capital expenditures on modernization of the inverter power section.

RELEVANCE of the research consists in estimation of the reliability parameters of in-house power supply systems for enterprises with transformer substations with a voltage of 10/0.4 kV. The proposed study analyzes reliability indicators for in-house power supply circuits with various types of redundancy: without redundancy; with low-voltage redundancy (installation of 0.4 kV circuit breakers), with medium-voltage redundancy (with installation of disconnectors and a circuit breaker), without redundancy on the low side; as well as with double redundancy, which additionally provides for the installation of disconnectors and a circuit breaker, as well as circuit breakers for 0.4 kV. METHODS. The research uses the fundamentals of reliability theory, probability theory, and statistical data processing. Based on the calculation results and the information obtained, graphical dependences of the uptime of in–shop power supply systems with dual transformer substations are constructed, depending on the nominal capacity of the shop transformers for four circuit options: without redundancy; with redundancy for LV; with redundancy for MV; with double redundancy – for MV and LV. The condition for the rationality of the construction of the power supply scheme is the smallest number of transformer substations, and, accordingly, distribution transformers, with the accepted value of the load factor equal to 0.8. When comparing the results obtained, it was found that the longest operating time for failure, equal to 25.6 years, is achieved with double redundancy, the smallest – equal to 5.4 years – in the absence of redundancy. The reliability parameters of the system are being investigated, namely, the failure rate parameter and the operating time for circuit failure when the number of two-transformer substations (N_tp) changes from 1 to 5, as well as with different capacities of 10/0.4 kV workshop transformers (from 25 to 2,500 kVA). RESULTS. The results obtained show that the value of the operating time for failure is T for the scheme without redundancy is 4.38 and 4.29 times lower compared to the scheme with redundancy for MV and LV, respectively, and 4.72 times lower for the scheme with double redundancy. CONCLUSIONS. The conducted studies show that it is rational to use the minimum number of transformer substations N_tp, equal to 1 (in the absence of redundancy) or 2, since with N_tp = 3-5 the operating time for failure is minimal and is approximately 1.01 years with a load factor of transformers equal to 0.8. As a result of the research, it was found that the maximum operating time A failure time of 6.4 years was obtained for the scheme with double redundancy, and a minimum time of 1.01 years was obtained in the absence of backup elements.

RELEVANCE. The development of charging infrastructure, both quantitatively and qualitatively, is an essential condition for the further expansion of promising low-carbon vehicles. In this regard, the design of power supply system’s taking into account the characteristics and operating modes of fast charging stations (CS), their energy efficiency and technical operation are becoming increasingly important. THE PURPOSE - to experimentally evaluate the characteristics of manufactured in Russia CS under real-life operating. To implement charging sessions of passenger electric vehicles (EV) and plug-in hybrid electric vehicles (PHEV) common in the Russian Federation via the measurement and recording of the CS input and output parameters. To experimentally evaluate the CS energy efficiency its relationship with of the charged EV characteristics. METHODS. The objectives were achieved through the organization of four Russian manufactured multi-port CS trial operation and using ten popular EV models. During the trial operation, standard charge procedures were performed, the input AC and output DC characteristics of the CS are measured. Charging station performance was recorded throughout the entire charging session using both external measuring instruments and the built-in capabilities of the CS themselves. RESULTS. Time dependences of the CS input and output power, charging current and voltage, state of charge, and energy were obtained while charging EV battery from minimum to maximum state of charge (SOC). The measurement results allowed us to quantify the CS energy efficiency and establish the relationship between CS efficiency, charging power, and the initial battery SOC. Charging profiles reflecting the characteristics and nature of charging power changes during the energy replenishment process were obtained for popular mass-produced EV and PHEV in Russia. CONCLUSION. The results presented in this article are of practical interest for charging stations operating modes and characteristics analysis and can be useful in modeling and designing charging infrastructure facilities, forecasting and managing electricity consumption.

The relevance of this research is driven by the growing need to create compact, high-energy power sources for autonomous systems, such as unmanned aerial vehicles (UAVs), where traditional lithium-ion batteries exhibit limitations in specific energy capacity. A promising direction is the development of microturbine generators based on microelectromechanical systems (MEMS), capable of converting the chemical energy of fuel into electrical energy with high efficiency. PURPOSE: To fill the gap in the domestic literature on microturbine technologies, systematize global experience, and identify prospects for the development of high-energy MEMS power supplies in the Russian Federation. To analyze the designs, materials, manufacturing technologies, and thermodynamic characteristics of microturbines. METHODS. This study utilizes methods of system analysis of scientific and technical literature, a comparative evaluation of design solutions, and a thermodynamic calculation based on the Brayton cycle and fundamental laws of thermodynamics. RESULTS. A comprehensive review of key technological solutions in the field of microturbines, including the use of gas bearings, heat-resistant materials (silicon carbide), micromachining methods, and design features for the microscale. An evaluation of the output power of a microturbine generator with a fuel consumption of ~5.84 ∙ 10⁻⁹ m³/s showed that this machine is capable of producing approximately 100 W. Complex technological aspects during the development process included ensuring stability at ultra-high speeds, microcombustion control, thermal conditions, and component integration. CONCLUSION. MEMS-based microturbine technologies offer significant potential for creating power sources with a specific energy density 10-20 times higher than the best batteries. Despite existing technological barriers, further research in optimizing thermodynamic cycles, developing new materials, and improving micromachining methods offers prospects for developing domestically produced, highly efficient power systems for UAVs and other autonomous systems, which is key to strengthening technological sovereignty.

RELEVANCE. Single-phase-to-ground faults remain one of the most common types of damage in distribution networks with isolated neutral. Arc-ing, intermittent single-phase-to-ground faults pose a serious threat to the power system's electrical equipment due to the transient processes occurring in the network during such faults. The prolonged flow of single-phase-to-ground fault currents in a cable line causes heating and can lead to a phase-to-phase short circuit. The development of high-speed and selective relay protection will prevent damage and ensure a reliable power supply to consumers. PURPOSE. To improve protection speed, the Clarke transform is applied, which combines the instantaneous values of the three phase currents to obtain an informational feature of a fault. It is necessary to develop a starting unit for single-phase-to-ground fault protection using the Clarke transform and to determine the properties of the resulting starting unit. METHODS. The Matlab software suite with the Simulink extension package was used for simulation modeling of current oscillograms under various operating conditions of an electrical network with an isolated neutral. The simulation results allowed for the development of a protection starting unit that utilizes the Clarke transform and features increased speed. RESULTS. A simplified structural and functional diagram of a starting unit for protection against single-phase-to-ground faults has been developed. A comparative sensitivity assessment was conducted with relay protection currently used in networks. The sensitivity of the developed protection unit during arc-ing intermittent single-phase-to-ground faults exceeds that of existing similar technical solutions. CONCLUSIONS. The research results are promising for creating new protection against single-phase-to-ground faults in networks with an isolated neutral, utilizing the Clarke transform.

The article is devoted to the problem of choosing the optimal temperature schedule in the heat supply system. RELEVANCE. Currently, numerous variants of temperature schedules are used in heat supply organizations without a feasibility study of their application. There is a problem of the lack of a unified methodology for choosing the optimal temperature schedule for the heat supply system. The correct choice of the temperature schedule determines the energy efficiency and reliability of the heat supply system. PURPOSE. Analysis of existing methods for selecting the most appropriate temperature schedule for the heating network, assessment of their sufficiency to solve the problem of optimizing the heat supply system. METHODS. To solve this problem, the authors conducted a literature review of existing approaches and methods for selecting temperature schedules in various climatic and operational conditions. CONCLUSION. Based on the analysis, it is concluded that it is necessary to develop a unified methodology for choosing the optimal temperature schedule. In order to be able to use it in practice, the developed methodology should take into account the entire range of parameters of the heat supply system and at the same time minimize the complexity of calculations. The factors proposed to be taken into account when developing a methodology for choosing the optimal temperature schedule are given, including specific energy costs, heat losses in networks, reliability of heat supply taking into account temperature deformations, operating and capital costs, as well as tariff consequences for consumers.

RELEVANCE of the study is determined by the implementation of the oil refinery modernization program in the Russian Federation, aimed at increasing the depth of oil refining and improving the quality of petroleum products. The increase in the share of deep processing processes leads to a significant change in the balance of hydrogen at refineries, which requires a comprehensive analysis of its generation and consumption. OBJECTIVE. To improve the energy efficiency of refineries by increasing the depth of oil refining through the use of hydrogen or hydrogen-containing gas (HCG). To analyze the issues of hydrogen consumption and generation in refinery technological processes. To establish the dependence of hydrogen consumption on the depth of oil refining. To evaluate the most effective methods of hydrogen production for use at refineries. METHODS. The study is based on the analysis of standard indicators and technological characteristics of the main oil refining processes (isomerization, hydrotreating, hydrocracking, catalytic reforming). Based on the material balances of these processes, a correlation was established between the depth of oil refining and the volume of hydrogen consumption at refineries. RESULTS. The article presents the specific energy consumption for the main process units. It has been established that achieving a refining depth of over 85% requires a significant increase in hydrogen consumption and the introduction of additional hydroprocessing of residual fuel oil. Catalytic reforming is identified as a key source of hydrogen, while hydrotreating and hydrocracking are its primary consumers. CONCLUSION. With the need to increase refining depth and depleting light crude oil reserves, there is a steady trend toward increasing hydrogen consumption for refinery processes. The development of the oil refining industry requires modernization and the introduction of new, efficient hydrogen generation facilities.

Purpose. The paper shows the possibility of using Balakhtin coal for the production of synthesis gas by gasification followed by its use in a gas turbine. The purpose of the study was to evaluate the efficiency of the Balakhtin coal gasification process and determine the main characteristics of the generated generator gas. It is shown that coal gasification produces a generator gas with an average heat of combustion of 4608.41 kJ/Nm³. As a result of the calculation, the number of main components in the gasification products, the excess air coefficient, the proportion of water vapor introduced, and the synthesis gas output were determined. The resulting synthesis gas can be sent to a gas turbine to generate electricity. The article presents the effect of natural gas and generator gas produced during gasification of Balakhtin coal on the energy characteristics of a gas turbine. This comparison makes it possible to predict changes in the energy characteristics of the gas turbine unit (GTU). Methods. To solve the tasks set in the scientific article, a computational research method was used. The following research objects were selected: Balakhta brown coal and synthesis gas obtained during coal gasification. Results. The results of computational studies of solid fuel gasification in a flow-through gas generator are presented. A comparison of the effect of the obtained synthesis gas and natural gas on the energy characteristics of a gas turbine is presented. Conclusion. The synthesis gas produced as a result of gasification is a promising alternative fuel for gas turbines, which will reduce the consumption of natural fossil fuels and reduce the negative impact of coal on the environment.

RELEVANCE of the study is since improving the efficient, economic and environmental performance of reciprocating engines (ICE) powered by alternative gaseous fuels remains an important task for the development of mechanical engineering and energy. Therefore, the creation of mathematical models of the working cycle of ICEs operating on different gases and improving their energy efficiency is relevant for science, technology and technology. The PURPOSE of the study was to increase the efficiency and energy efficiency of an ICE-based electric generator by optimizing its operating cycle parameters after replacing the base fuel (propane-butane) with synthesis gas based on numerical modeling. METHODS. The object of the study was a 1 kW electric generator based on a single-cylinder ICE with external mixing. The article describes the main approaches to creating a mathematical model of the engine operating cycle, the physicochemical properties of the base fuel (propane-butane) and a new laboratory synthesis gas. The simulation results are verified through experimental studies. The differences between simulation and the experiments for the key parameters (power, efficiency, air and fuel consumption) did not exceed 4.0%. The efficiency of the ICE was chosen as a key criterion for optimizing the operating cycle. RESULTS. Data on the performance of an ICE powered by propane-butane and synthesis gas for different operating cycle parameters (compression ratio, excess air ratio, ignition timing angle, gas exchange system resistance) were obtained based on mathematical modeling. CONCLUSION. It is shown that replacing propane-butane fuel with synthesis gas causes a decrease in engine efficiency of up to 33% (the efficiency of the basic ICE was 0.179 versus an efficiency equal to 0.119 for the efficiency of the converted ICE for a power of 0.59 kW). As a result of optimization, the efficiency of the converted syngas engine was 6.1% higher than that of the base propane-butane ICE, and the power drop did not exceed 8%. Thus, careful refinement of the operating cycle parameters makes it possible to increase the energy efficiency of a synthesis gas engine to the level of an ICE running on traditional fuels.

RELEVANCE. The use of domestic software systems in the energy industry is associated with the import substitution of foreign programming platforms. Currently, the SimInTech dynamic modeling environment for technical systems is widely used for modeling processes in the thermal power industry. THE PURPOSE. To describe the methodology for modeling the scheme of a Rankine steam turbine installation in the SimInTech dynamic modeling environment. Create blocks of a submodel for calculating a steam turbine, pump, and condenser. To develop a user-friendly interface for input of initial data and visual visualization of calculation results. METHODS. The developed method for calculating the scheme of a steam turbine installation in the SimInTech environment is based on the scheme of a general model. Separate submodels of turbine, condenser and pump design schemes are being developed. The Properties of substances library is used to determine the thermodynamic parameters of water and steam. RESULTS. The article describes a method for modeling a Rankine cycle circuit, and shows the features of creating submodels of thermal power elements of circuits. For each element of the submodel, the source data is visualized in a convenient format, and the intermediate results are monitored over communication lines. The results of calculating the thermodynamic parameters and performance indicators of the scheme are recorded in a separate file, which allows you to analyze the information obtained for various source data variants. CONCLUSION. The developed submodels of the turbine, pump and condenser make it possible to perform thermodynamic calculation of the elements with a high degree of accuracy. A model of a steam turbine installation is created from individual elements of the submodels. It is possible to implement a more complex model by creating additional submodels, such as an intermediate superheater, heaters and other elements.

The RELEVANCE of the research lies in the development of new methods for organizing the removal of low-potential heat from data centers, power electronics and other natural and technological sources, as well as in obtaining new dependencies for assessing the maximum increase in the effective coefficient of performance (COP) of simple two-stage heat pump (HP) cycles with a separator. The GOAL of the work is to optimize the operation of a simple two-stage heat pump with a separator. METHODS. The CoolProp library was used for calculating the thermodynamic cycle of the heat pump and the efficiency of the compressors was taken into account. A law was introduced to optimize the operation of the heat pump, which relates the power fraction of the first stage to the temperature in the separator. To assess the maximum efficiency of the heat pump, it was assumed that the refrigerant enters the compressor as an unsuperheated vapor and pure condensate enters the thermostatic valve. RESULTS. A general scheme is presented and the principle of operation of a two-stage heat pump is discussed. Based on thermodynamic calculations, the thermal performance of the cycles is obtained. The coefficient of relative increase in the effective COP for R410a, R141b, R600a and R134a refrigerants is determined. It is shown that the existence of a maximum in the effective heat transformation coefficient is due to the presence of two effects. Functions based on physical laws are derived that determine the maximum increase in the heat transformation coefficient and its position. CONCLUSION. A detailed analysis of the reasons for the increase in COP relative to a single-stage cycle has been conducted. The obtained dependencies are useful for assessing the effect of using a two-stage heat pump in practice. The developed heat pump scheme can be used to extract low-potential heat from data centers, power electronics, the ground and other sources with greater efficiency than a single-stage cycle.

RELEVANCE. The relevance of the study is due to the increasing demands for energy efficiency of industrial enterprises in the context of climate change. Cooling towers are key elements of water recycling systems at enterprises in the petrochemical and energy industries of the Republic of Tatarstan. TARGET. To analyze modern approaches to increasing the efficiency of cooling towers in the warm season, taking into account the climatic conditions of Tatarstan, and also to study the possibility of using an evaporative air cooling system in front of the air intake windows of a cooling tower of a thermal power plant. METHODS. To achieve the set goal, an analysis of literary sources and technical documentation of the operating facility, thermodynamic calculations of heat and mass transfer processes of evaporative cooling of circulating water and the influence of its temperature on the operation of the steam turbine unit were used. RESULTS. The implementation of the outdoor air pre-cooling system is a technologically sound solution for optimizing the operation of cooling towers under conditions of increased temperature loads. This system ensures thermodynamic stabilization of the heat exchange process by reducing the temperature of the incoming air flow. CONCLUSION. The implementation of this engineering solution ensures the stable operation of the cooling system in a wide range of meteorological conditions while maintaining technological parameters throughout the year. The introduction of pre-adiabatic air flow cooling technology contributes to a significant increase in the energy efficiency of the power unit, namely: turbine power increase: 492 kW; annual additional energy production: 1.7 GWh; economic effect: 14.67 million rubles / year; payback period of less than 2 years.