RELEVANCE. Recently, power transformers with mineral biodegradable insulating oil have been increasingly used, since it is environmentally friendly and biodegradable. Power transformers are the main and extremely important equipment in electric power systems. METHODS. Diagnostic methods are of particular importance for the stable operation of the system. Gas analysis (GA) of mineral oil has its own diagnostic methods that cannot be directly applied to other oils. RESULTS. The relationship between gas evolution and destructive processes occurring in mineral oil is considered. In this study, tests were carried out for local heating, partial discharge and arc discharge in oil to study gas formation under these conditions. Based on the results obtained, gas formation mechanisms were discussed depending on the heating temperature, discharge energy and other factors. CONCLUSION. The methods proposed in this paper, based on experimental data, are important, since they indicate promising areas for diagnosing mineral oils. The accuracy of these methods can be improved by optimization using data from operating transformers.

RELEVANCE. The paper presents proposals for optimizing the existing methods for monitoring the technical condition of self-powered neutron detectors (SPNDs) of the in-reactor monitoring system (IRMS), used, in particular, at VVER-1200 nuclear reactors, which allow increasing the accuracy of diagnosing the operability or inoperability of such sensors. OBJECTIVE. To evaluate the currently used methods for monitoring and diagnosing sensors. To present proposals for optimizing the monitoring of the technical condition of SPNDs by increasing the volume of diagnostic information. To describe the developed software that allows determining the parameters of the SPNDs measuring circuit to diagnose the technical condition of the sensor. To present the results of processing the SPNDs readings of the VVER-1200 reactor of the Leningrad NPP using the developed software. METHODS. When solving the tasks, the provisions and methods of technical diagnostics were used, as well as the theory of electrical circuits and numerical methods for solving equations implemented in the developed software using MatLab. RESULTS. The article describes the relevance of the topic, presents a methodology for optimizing the monitoring of the technical condition of the SPNDs, based on expanding the volume of diagnostic information used. The described methodology is used as a basis for creating specialized software in the MatLab environment. The developed software was used to determine the insulation resistance of the measuring circuit of the SPNDs of VVER-1200 at the Leningrad NPP. CONCLUSION. Using the proposed method for monitoring the technical condition of the SPNDs allows increasing the reliability of the SPNDs by using an expanded set of information about the technical condition of the sensor. The results of calculations using the developed software based on data from Leningrad NPP-2 showed that the range of operability of the SPNDs in terms of insulation resistance can be reduced by 3-4 orders of magnitude. Comparison of the value of the emitter generating capacity measured during the reactor campaign with the one calculated using the program showed a high degree of accuracy.

THE PURPOSE. Ensuring the safe operation of an operating facility in the event of emergency situations, such as an unacceptable change in engine torque during a technological operation. METHODS. The tasks set during the study were solved by means of mathematical modeling in the Matlab Simulink environment and practical research. RESULTS. The introduction of fuzzy logic-based correction blocks into standard control systems made it possible to ensure that the object would stop when the engine torque changed critically. CONCLUSION. The use of correction units developed on the basis of fuzzy logic on industrial multi-drive units, compared to the use of traditional control systems, allows ensuring the safety of equipment operation in the event of emergency situations, leads to a decrease in the occurrence of factors that may result in mass defects in products, equipment failure. The proposed regulator allows the use of converters installed at facilities that do not provide for a response to emergency situations, such as an unacceptable decrease or excess of engine torque.

THE RELEVANCE of the study lies in solving the important problem of increasing the stability and reliability of electrical engineering systems (EES). The AIM of the work is to reduce the number of forced shutdowns of electrical equipment during voltage drops caused by short circuits inevitable during operation of electrical networks. The issues of selecting the parameters of minimum voltage protection in electrical engineering systems are considered. As a result of the analysis of operational data and simulation modeling of voltage drops, it was found that when using minimum voltage protection (MVP) with independent characteristics, more than 50% of protection trips with load disconnection occur unreasonably. The basis for disconnecting the load is a violation of the stability of the electrical engineering system. METHODS. The use of MVP with a dependent response time characteristic on the residual voltage value close to the stability limit reduces the share of unreasonable MVP trips, but does not eliminate them completely. To minimize the number of unreasonable protection trips, it is necessary to adapt the parameters of the MVP characteristic to the stability limit dependent on the load and power source mode. To monitor the stability boundary parameters of the electrical engineering system during operation, it is proposed to use artificial neural network algorithms. RESULTS. The tested Levenberg-Marquardt (LM) algorithm showed sufficient accuracy of stability monitoring based on the parameters of the electrical engineering system measured during operation. It is shown that the use of the dependent characteristic of the MVP, the parameters of which are adapted to the load and power source mode using neural network algorithms, allows for approximately a twofold reduction in the number of unjustified load shutdowns and an increase in the stability of the electrical engineering system of continuous production.

THE RELEVANCE of the study lies in modeling and studying the operation of energy management systems based on rule-based strategies as applied to a hybrid electric powertrain with a battery and a fuel cell stack. THE PURPOSE of the work: to consider the problems of increasing energy efficiency, cost-effectiveness and durability of power sources in a hybrid electric powertrain using energy control strategies, to design a simulation model of a hybrid system with two energy sources, to develop the model controlled by four rule-based strategies. RESULTS. During researching the problems, models and algorithms were developed in the MatLab software. The article describes the relevance of the research, considers energy management control strategies and features of their operation. Simulation of the hybrid powertrain with different control strategies was described, the possibility of ensuring the operation of the powertrain with a given load cycle with the required conditions was considered. The results of the simulation of the operation are presented in the form of overall efficiency and cost-effectiveness of the hybrid powertrain with different control strategies. CONCLUSION. All the studied strategies ensure the operation of the powertrain in the entire load range with high efficiency. The most effective strategy is the state machine control strategy, it implements maximum efficiency on the presented load cycle. The most cost-effectiveness strategy, in which the consumption of hydrogen and air is minimal, is the strategy based on fuzzy logic algorithms.

THE RELEVANCE of this work lies in the analysis of the local robustness of a controlled electric drive, which is a key task in the case of operation under conditions of uncertainty, when one of the most important requirements for the system is to maintain the ability of the object of study to maintain stability and the required quality of control processes under the influence of destabilizing factors of various physical natures. PURPOSE. The paper studies the system properties of a positional electric drive with the definition of quantitative estimates of permissible variations in the parameters of the mathematical model of the system. The target setting of this analysis is to evaluate direct and indirect indicators of the quality of the positional electric drive operation based on the interval polynomial formed as a result of the study using computer modeling methods. Analysis of local robustness allows us to estimate the boundaries of asymptotic stability of the system under study under parametric disturbances. Formation of an interval polynomial based on the apparatus of Hermite-Bieler polynomials and computer modeling of the positional electric drive under study in the range of calculated boundaries of parameter variations is an important and urgent task. METHODS. When solving the research problem, methods of mathematical analysis, stability theory and theory of automatic control systems, vector-matrix equations in the form of state spaces and differential equations in operator form, the mathematical apparatus of Hermite-Biehler polynomials, as well as modeling of the dynamics equations of the electric drive under study in a software environment were used MatLab. RESULTS. In this work, the problem of analyzing the local robustness of a positional electric drive is solved and an interval polynomial with lower and upper bounds of the coefficients is obtained that accompanies the characteristic polynomial of the system under research. Based on the results of the analysis, computer modeling was carried out and quantitative estimates of the quality indicators of the functioning of the electric drive under research were obtained in the time and frequency domains. Graphs of additional motion are presented, which allow, when forming control objects of this class with sensors and coordinate controllers, to carry out a comparative analysis of the configuration of the system under research for the potential stability of performance indicators under conditions of parametric disturbances. CONCLUSION. The research of the system properties of a positional electric drive according to the output coordinate of its mathematical model from the point of view of local robustness analysis allows us to evaluate the range of parameter variations according to the degree of achievability of the required indicators of the quality of functioning of the object using the characteristic features of various control algorithms. The results of the analysis provide the opportunity to rationally distribute control resources based on classical algorithms and evaluate the effect of introducing output coordinate controllers into the system under conditions of parametric disturbances. It is also possible to compare options for the formation of correction algorithms using classical methods with an adaptive approach of search or analytical (non-search) types, based on the use of reference models of the research object with identification or direct types of control.

THE RELEVANCE. Battery energy storage systems reduce peak loads in external power supply systems, which helps reduce operational energy losses and allows for the selection of lower-power transformers during the design stage. Residential and public buildings benefit from reduced electricity bills during peak hours, as well as the ability to connect to electric charging stations installed in adjacent areas. THE PURPOSE. Developing a methodology for selecting the capacity and energy capacity of battery energy storage systems used in urban infrastructure to limit power consumed from the power grid during peak load hours, as well as the subsequent development of proposals for amending SP 256.1325800.2016 "Electrical Installations of Residential and Public Buildings. Design and Installation Rules." METHODS. The study utilized in-kind measurements of daily power profiles for residential and public buildings, specifically apartment buildings with electric stoves ranging from 11 to 25 stories tall, kindergartens and schools, as well as public buildings serving cultural and leisure purposes and shopping centers. A typical daily power profile was generated for apartment buildings. This profile demonstrates the use of the energy balance of the storage device's charge and discharge to calculate the maximum required power and energy capacity. RESULTS. The specifics of connecting an energy storage system to the city's power grid are discussed. It is shown that the storage system achieves its maximum output when charged while drawing constant power from the grid. CONCLUSION. Charging batteries with a stabilized, reduced current, which extends their lifespan, is beneficial for energy storage systems operating in short-term discharge modes. Based on the obtained typical power profile of an apartment building, calculation formulas are proposed for selecting the parameters of energy storage systems installed at facilities with recurring load patterns.

RELEVANCE of the study means the recommendations development for the efficient energy utilization of sewage sludge in the fluidized bed boilers. THE PURPOSE. To consider problems of energy utilization of sewage sludge. Conduct an energy audit of the fluidized bed boiler E-75-3,9-440 DFT during the combustion of sewage sludge together with wood waste from pulp and paper industry. Conducting a proximate analysis of sewage sludge and wood waste. Conducting an elemental analysis of the fluidized bed material. METHODS. Samples of sewage sludge and wood waste were taken from the fuel supply line of boiler E-75-3,9-440 DFT. Retzsch RM 200 ball drum mill and a Retzsch AS 200 Control sieve analyzer were used to prepare samples. Ultimate analysis of sewage sludge was performed by X-ray fluorescence spectroscopy on an EDX-8000 spectrometer. This method identifies metals and elements of the sample by detecting their energy signatures. Hydrogen, nitrogen and carbon content was determined using the EuroVector EA-3000 analyzer. Calorific value of the studied samples was determined using an IKA C 2000 Basic Version 2 calorimeter with a LOIP FT-216-25 liquid cryothermostat. Energy audits were carried out under the established thermal regime of the boiler. RESULTS. Research results have shown that during the combustion of sewage sludge in a fluidized bed boiler E-75-3,9-440 DFT operating conditions are very different from the calculated ones, which is associated with the problems of slag formation, erosion due to the high ash content of the sludge, as well as problems associated with the operation of the fluidized bed due to the high humidity of the fuel. CONCLUSION. Recommendations are given on improving the energy efficiency of wastewater sludge combustion in a fluidized bed boiler E-75-3,9-440 DFT.

THE RELEVANCE of the work is to determine the optimal characteristics of a combined power plant (CPP) based on hydrogen fuel cells for the urban electric passenger vehicle KAMAZ-6290 with a gross weight of 18 tons and a length of 12 meters. THE PURPOSE. Determine the optimal characteristics of the power plant for the vehicle by creating a mathematical model that allows you to optimize the characteristics. METHODS. Creation of a simulation mathematical model of the vehicle with a power plant in the software Simcenter Amesim, in which the system components are simulated. Based on the results, the parameters and characteristics of the CPP are optimized. CONCLUSION. The results of this work are used in selecting the optimal characteristics of the CPP under operating conditions as part of the vehicle.

THE RELEVANCE. This article provides a review of modern approaches to the optimization of microgrid planning, including multi-objective optimization methods, uncertainty considerations, and the application of intelligent algorithms. Microgrids, as a key component of modern energy systems, integrate distributed energy resources, storage devices, and loads, thereby enhancing the efficiency, reliability, and environmental sustainability of energy supply. METHODS. The paper examines key optimization models, such as minimizing operational costs, reducing emissions, and improving power supply reliability. Special attention is given to methods for addressing uncertainties related to renewable energy sources and load variability, as well as the role of energy storage systems and demand response. The article also analyzes traditional and intelligent optimization algorithms, including genetic algorithms, particle swarm optimization, and deep learning. RESULTS. The application of modern models such as SRSM-SOCR, modified Bet algorithm (MBA), deep reinforcement learning (DRL) and deep recurrent neural network (DRNN) made it possible to reduce the operating costs of microgrids by 18-25%, increase the share of generation from renewable sources to 70-75% and reduce CO₂ emissions by up to 60%. Real-life examples of microgrids in Germany and Greece are also presented, confirming the effectiveness of these approaches. CONCLUSION. Based on a literature review, key directions for future research are identified, such as the integration of transfer learning and reinforcement learning to enhance model adaptability. The findings of this study can be useful for developing effective microgrid management strategies in the context of increasing renewable energy penetration and evolving energy system requirements.

THE RELEVANCE. Heating of greenhouse spaces during the winter season has been and remains one of the most energy-intensive cost items in greenhouse operation. The integration of renewable energy sources with high-temperature thermal storage systems helps to mitigate the imbalance between energy generation and consumption; however, this approach requires validated ground heat transfer models for the reliable design of subsurface heating systems. THE PURPOSE. To perform numerical modeling and experimental validation of heat transfer from a buried pipe, considering soil moisture content, for subsequent application in localized greenhouse soil heating systems. METHODS. Two series of laboratory experiments were conducted using dried (moisture < 10%) and moistened (moisture ≈ 45%) loamy soil. Soil temperature was monitored using 20 DS18B20 sensors and a UTi260B thermal imager. A two-dimensional computational domain was developed, and a mesh grid was constructed. Transient numerical simulations were performed in ANSYS Fluent. The unsteady-state heat conduction equation was solved using the finite volume method, incorporating actual thermophysical properties of the soil. RESULTS. The average relative deviation between simulated and experimental temperatures was below 6% for dried soil and around 4% for moistened soil, confirming model accuracy. Moistened soil exhibited 15-20% faster heating and achieved 2-3 °C higher temperatures in the 2-4 cm depth range due to reduced thermal resistance in the saturated pore structure. Thermographic imaging showed that the effective heating width of a single pipe was limited to 1-2 cm, indicating the need for a pipe bundle or coil arrangement to ensure uniform heating of the root zone. CONCLUSION. The validated model serves as a tool for optimizing the geometry of subsurface pipe layouts based on soil moisture content.

THE RELEVANCE. The issues of efficient use of fuel and energy resources in the Russian industry remain extremely important, which is confirmed by the adoption of a number of legislative and regulatory documents at the federal and regional levels. Historically, the structure of energy complexes of enterprises, including production using oil systems, was formed in conditions of low energy prices, which led to insufficient energy efficiency of technological processes. In this regard, the modernization of existing components, in particular, oil heating systems, using modern methods of technological modeling, becomes an urgent task. THE PURPOSE. The study of oil heating unit in order to optimize its thermal regime, reduce energy losses and develop measures to improve energy efficiency using technological modeling tools is the purpose of this study. METHODS. To achieve the set objectives the following methods were used: system analysis of thermal and technological processes, mathematical and computer modeling of heat exchange in the oil heating unit, methods of energy-technological combination to identify energy saving reserves. RESULTS. Within the framework of the research there were carried out: analysis of heat losses in the oil heating unit, modeling of heat flows taking into account changes in viscosity and heat capacity of oil, evaluation of efficiency of heat exchange equipment and identification of “bottlenecks”. Proposed solutions: introduction of an additional heat exchanger for waste gas heat recovery, optimization of heating modes by means of automation of temperature parameters control, use of recuperative schemes to increase system efficiency. CONCLUSION. Implementation of the proposed measures will result in savings of up to 6.55 million rubles per year. Application of technological modeling tools in modernization of oil heating unit allows to optimize thermal processes, reduce energy losses and increase economic efficiency of production. Implementation of the proposed solutions will provide significant energy savings with a relatively short payback period. The implementation of this project will contribute to the digital transformation of heat transfer processes and energy efficiency in the petrochemical industry through the application of artificial intelligence and machine learning technologies. This corresponds to the key directions of the Strategy for Scientific and Technological Development of the Russian Federation, including the transition to intelligent production systems, big data processing and the introduction of automated control methods. Thus, the proposed approach opens up new opportunities for the digitalization of petrochemical industries, increasing their efficiency, environmental friendliness and competitiveness in accordance with the priorities of scientific and technological development of the Russian Federation.

RELEVANCE. Pulp and paper production is an energy-intensive industry with significant amounts of unused secondary energy resources (REM), especially low-potential heat (40-80°C). In the context of growing energy efficiency and environmental requirements, the recovery of these wind turbines from sources such as wastewater and recycled water, ventilation emissions, and heat cooling of intermediates is becoming not just a promising area, but an urgent necessity. This makes it possible to reduce fuel consumption, energy consumption and harmful emissions, thereby increasing the competitiveness of enterprises. purpose. The aim of the study is to increase the energy efficiency of a complex industrial heat and technological scheme of pulp and paper production using methods of structural and thermodynamic analysis. These analysis methods make it possible to objectively assess the potential of recycling secondary energy resources and select the most effective schemes of wind power recovery systems. METHODS. Exergetic analysis revealed significant unused heat losses in pulp and paper production, in particular, in drying plants with an efficiency of only 46.9%. It has been revealed that the flows of exhaust air, waste and recycled water, and the upper product of the columns have the greatest potential for recovery. Their utilization by means of heat pumping units can significantly increase the energy efficiency of production, reducing energy costs and thermal pollution of the environment. results. Thermodynamic analysis revealed significant unused losses in key production streams (waste air, wastewater and recycled water. the top product of the columns). A system for their recovery using heat pumping units (TNUS) has been developed, which makes it possible to increase the total energy utilization of the system from 17.88% to 92.58%. The introduction of TNW provides significant savings in thermal energy and reduces the environmental burden of production. conclusion. To solve this problem, a comprehensive heat recovery system based on thermal transformers – heat pump installations has been developed. Its implementation will make it possible to utilize 10.13 MW of thermal capacity from waste streams, increasing the overall energy efficiency of production.