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Grid-Forming and Grid-Following Based Stability Assessment of Large-Scale Renewable Integrated Power Systems Under Low-Inertia Conditions
Relevance: Low-inertia renewable-integrated power systems face increasing frequency and voltage stability chal lenges under high penetration of inverter-based generation. Objective: This study develops a mathematical–simulation model for evaluating frequency and voltage stability in renewable-integrated power systems using GFL/GFM inverter dynamics, equivalent grid characteristics, virtu al inertia, and reactive power control under varying renewable penetration scenarios. Methods: Thevenin-based equivalent modeling, dq-frame inverter control, virtual inertia, droop algorithms, and parametric dynamic simulations were applied. Results: Increasing GFL penetration reduced effective inertia, enlarged frequency oscillations, and prolonged stabilization time, while GFM units-maintained voltage and frequency recovery stability.
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Hybrid AI-Driven Monitoring and Reliability Enhancement Framework for Centralized Inverters in Large-Scale Solar Power Plants
Relevance: Reliability degradation of centralized inverters significantly affects operational stability and efficien cy of large-scale photovoltaic power plants. Objective: This study develops a hybrid AI-driven monitoring framework integrating SCADA, thermal sensing, partial discharge analysis, and Digital Twin technologies to improve reliability assessment, predictive mainte nance, and operational efficiency of centralized inverters in utility-scale solar power plants. Methods: Comparative reliability analysis, sensor-based diagnostics, AI/ML prediction, and Digital Twin-based monitoring architectures were investigated. Results: Hybrid monitoring improved early fault detection accuracy by 34,5 % and reduced unexpected inverter downtime by 27,8 %.
Joint use of the indicators for forecasting energy systems development
development. The accuracy and balance of forecasts in determining the energy and economic indicators of energy systems form the basis for the correct formation of the future fuel and energy complex. Currently, the main fore casting indicators are two: EROEI – energy and LCOE – economic. At present, these indicators are considered separately, independently of each other. At the same time, it is evident that a systematic approach to forecasting dictates the simultaneous consideration of both indicators. This will contribute to improving forecast characteris tics, their objectivity, accuracy, and timeliness. Therefore, analyzing and conducting research on improving fore casting models with simultaneous consideration of the EROEI/LCOE combination of indicators, as well as their mutual influence, is relevant. The influence of other variable factors affecting the forecast also needs to be taken into account. The simultaneous consideration of forecasting indicators will allow for a more accurate and objec tive determination of the future operational characteristics of energy systems. Aim: the objective of this work is to analyze the main forecasting indicators for the development of the energy sector, their mutual influence, and to develop recommendations that increase the efficiency of forecasting when simultaneously considering the EROEI and LCOE forecasting indicators. Methods: the work employs the following methods: comprehensive analysis, a systematic approach, multi criteria optimization, and utilizes international experience in energy forecasting. Results: this work analyzes the use of key performance indicators for the development of energy systems (energy – EROEI and economic – LCOE). These indicators are used in forecasting and justifying the development of energy systems. A mathematical relationship between EROEI/LCOE has been confirmed; it has been confirmed that the indicators influence each other, therefore, a systematic approach with multi-criteria evaluation of the simultaneous forecast combination of both indicators is necessary. This will ensure the objectivity and accuracy of energy system development forecasting.
Mathematical modeling of heat transfer processes in a hydronic radiant floor heating system
Relevance: at present, increasing the energy efficiency of buildings and the rational use of fuel and energy re sources are among the priority directions of the energy and construction sectors in the Republic. According to statistical data, about 40% of total energy consumption in residential and public buildings is attributed to heating systems. Therefore, the implementation of low-temperature and energy-efficient heating technologies plays an im portant role in solving energy and resource-saving problems. Hydronic radiant floor heating systems are character ized by high thermal comfort, uniform temperature distribution, and the ability to operate with low-temperature heat carriers. However, the efficient operation of such systems requires intensification of heat transfer processes, since the complex mechanisms of heat transfer from the heat carrier to the pipe wall, through the floor structure layers to the floor surface and indoor air directly affect energy efficiency. Therefore, mathematical modeling of heat transfer processes in hydronic radiant floor heating systems and evaluation of their impact on energy efficiency represent a relevant scientific and practical problem. Aim: the aim of this study is to analyze heat transfer processes occurring in a hydronic radiant floor heating system based on mathematical modeling, to determine the influence of heat carrier temperature, pipe spacing, and thermal properties of the floor structure on heat flux and energy efficiency, and to substantiate optimal operating modes from the viewpoint of energy and resource conservation. Methods: in the study, mathematical modeling methods based on heat balance equations, heat conduction (Fou rier’s law), convective and radiative heat transfer equations were applied to analyze heat transfer processes in the hydronic radiant floor heating system. The flow of the heat carrier inside the pipe, heat transfer through the layers of the floor structure, and heat release from the floor surface to the indoor air were modeled as sequential stages. Using computational and analytical methods, heat fluxes and energy efficiency indicators were evaluated for vari ous operating modes of the system. Results: based on mathematical modeling, the heat output capacity and energy efficiency indicators of the hydronic radiant floor heating system were analyzed. The calculation results showed that the heat carrier temperature and pipe spacing have a significant influence on heat flux. It was demonstrated that sufficient heat output can be achieved even under low-temperature operating modes, and energy-efficient operating regimes were substantiated. The obtained results confirm the effectiveness of hydronic radiant floor heating systems as an energy-efficient heating technology.
Adaptive 5D Simulation Frameworks Transforming Higher-Order Thinking in Engineering Education
Relevance: Higher-order thinking (HOT) skills - analysis, synthesis, evaluation, and creation - remain systematically underdeveloped in conventional instructional models. Objective: This paper presents a theoretical and empirical account of simulation-based learning (SBL) embedded within the five-stage 5D instructional framework (Define → Discover → Discuss → Demonstrate → Do), and proposes a HOT Index (HOTI) and a Learning Gain Model (LGM) to quantify and predict higher-order learning outcomes. Methods: A mixed-methods quasi-experimental study was conducted with 124 undergraduate STEM learners, drawing on cognitive load theory, constructivism, and adaptive instructional systems research. Results: Significant gains were demonstrated across all five HOT dimensions (Cohen’s d = 0,68–0,94, p < 0,001). Adaptive branching in the simulation engine reduced cognitive overload by 31% while increasing transfer accuracy by 24,3 percentage points.
Analysis of the energy consumption of electric vehicles at different speeds based on their parameters
daily. This trend is also occurring in Uzbekistan. This article examines the characteristics of electric vehicle pow er systems under various load conditions, depending on the main factors that affect the driving range. The charge in the battery and the power consumed are directly related, and the driving range establishes the balance. Fur thermore, the weight of the battery increases the mass of the electric vehicle, which leads to an overload and re duces the state of useful work. Therefore, this relationship plays an important role. This article analyzes the pow er required by an electric vehicle when moving at various weights and speeds on a flat surface without additional loads. Aim: the purpose of this article is to study the method for determining the required value of battery life, which is the energy source of electric vehicles, when moving at different speeds in 3 different weight positions of electric vehicles. Methods: in the research process, the average values of the studied technical characteristics of mid-class electric vehicles were taken into account to analyze the required power from the battery. The comparison method was used to determine the power required depending on the speed of movement of electric vehicles of different weights. Results: based on the study of the motion of an electric vehicle in a plane at a speed of 0-160 km/h with different weights in a calculation program, a graph and a table for assessing the effect are presented.
Study of air-cooling methods for air entering the gas turbine compressor
Relevance: the continuous growth of the population leads to a steady increase in the demand for electrical and thermal energy. In the Republic, the main generating capacities for electricity production are predominantly based on thermal power plants, combined cycle power plants, and cogeneration technologies. One of the key factors limiting the production capacity of modern gas-turbine thermal power plants is the inverse functional relationship between ambient temperature and gas turbine power output. An increase in atmospheric air temperature primarily leads to a decrease in its density, which in turn reduces the mass flow rate of air entering the gas turbine compressor. As a result, the electrical power generated by the gas turbine decreases by a certain amount. Environmental param eters such as humidity, pressure, and temperature may vary within a wide range depending on geographical location and seasonal factors. These factors have a direct effect on air density and an indirect impact on the power output of the gas turbine unit. During the summer period, an increase in temperature up to +45 0C leads to an increase in the specific work of the compressor, which results in a decrease in the turbine efficiency and a reduction in the gener ated power by up to 30%. In this study, it is shown that at the “Toshkent IEM” branch, due to the integration of evaporative (pad-type) cooling of the air at the inlet of the Hitachi H25 gas turbine compressor, the average power output has increased by 11–12%. Aim: it is planned to assess the potential for stabilizing generating capacities, improving operational efficiency, reducing the specific fuel consumption, and decreasing the amount of harmful substances emitted into the atmos phere under various climatic conditions, particularly through the application of technology for preliminary cooling of the ambient air entering the compressor. Methods: to assess the power losses occurring as a result of changes in ambient temperature at gas-turbine thermal power plants and to identify possibilities for their reduction, scientific studies conducted by foreign and domestic researchers were used, along with theoretical analysis, comparative analysis, approaches aimed at improving effi ciency, and methods of techno-economic evaluation. Results: the results of experimental and test studies carried out on the basis of monitoring the temperature and relative humidity parameters of the air entering the compressor of the Hitachi H25 gas turbine with a nominal capacity of 28.6 MW, installed at the “Tashkent Thermal Power Plant” branch, are presented.
Optimal Selection of Filter-Compensation Devices Based on a Genetic Algorithm in Low-Voltage Distribution Power Networks
Relevance: at present, the level of harmonic distortion in 0.4 kV low-voltage distribution networks is increasing due to the growing share of nonlinear loads, including electronic power supplies of LED lighting devices, switched-mode power supplies, frequency converters, and other electronic consumers. As a result, voltage nonsinusoidality increases, the current in the neutral conductor rises, additional power losses occur in transform ers and cable lines, and electric power quality indicators deteriorate. The use of conventional compensation de vices does not always ensure effective performance and, in some cases, may lead to resonance phenomena. Therefore, the optimal selection of filter-compensation devices for reducing harmonic distortion in 0.4 kV net works is an urgent scientific and practical task. Aim: to determine the optimal type, rating, and connection point of filter-compensation devices for reducing harmonic distortion in 0.4 kV distribution networks, decreasing the total harmonic distortion of voltage, reducing active power losses, and improving electric power quality indicators. Methods: in the study, a mathematical model of a 0.4 kV radial distribution network was developed, taking into account the harmonic composition of nonlinear loads. A genetic algorithm was used as the main method for solv ing the problem of selecting filter-compensation devices. In this process, the device type, rating, and connection point were optimized based on the objective function. The objective function included the total harmonic distor tion of voltage, the share of individual harmonics, active power losses, and the current in the neutral conductor. Results: the problem of reducing harmonic distortion in 0.4 kV distribution networks was analyzed using an 8-bus radial test system as an example. The results of assessing the influence of harmonic distortions caused by nonlinear loads on the network operating parameters are presented. The possibility of improving electric power quality indicators through the selection of filter-compensation devices based on a genetic algorithm was estab lished.
AI-Driven Real-Time Condition Monitoring and Reliability Enhancement of Centralized Inverters in Large-Scale Solar Power Plants
Relevance: Reliability degradation and fault diagnosis limitations significantly affect centralized inverter stability in large-scale solar power plants. Objective: This study investigates modern SCADA-, AI-, and thermal-model-based approaches for real-time condition monitoring, fault diagnosis, reliability assessment, and fault-tolerant operation of centralized inverters operating under dynamic renewable energy conditions. Methods: Comparative analysis of degradation models, SCADA monitoring, machine learning diagnostics, and Neutral Point Shift compensation methods. Results: Hybrid monitoring approaches improved fault detection accuracy, enabled adaptive post-fault recovery, reduced unplanned shutdown risks, and enhanced inverter operational reliability under variable operating conditions.
Analysis of reactive power source control based on converting the stator current received by an asynchronous motor into voltage
Relevance: in modern industrial and power systems, asynchronous motors are a widely used type of electric drive, their structural simplicity, high reliability and cost-effectiveness allow them to be used in pumps, fans, compressors and various technological devices. At the same time, one of the significant disadvantages of asyn chronous motors is their large consumption of reactive power, which leads to a decrease in the power factor, an increase in current loads and an increase in energy losses in electrical networks. In practical conditions, dynamic changes in motor load complicate the process of effective compensation of reactive power. Traditional capacitor bank control methods use voltage, active power or cosφ parameters, but these methods cannot respond to load changes in real time with sufficient speed and accuracy. Therefore, it is relevant to develop methods for control ling reactive power sources based on converting the current in the stator circuit of an asynchronous motor into a voltage signal. Stator current is a parameter that directly reflects the electromagnetic state of the motor and is sensitive to load changes, and its use allows for increasing the accuracy and speed of automatic reactive power control systems. Aim: to develop a method for controlling reactive power sources based on converting the current in the stator circuit of an asynchronous motor into a suitable voltage signal and to evaluate its effectiveness. At the same time, it is intended to determine the relationship between the stator current and the load and to justify the possibilities of automatic control of reactive power based on the generated signal. Methods: the values of stator current, voltage, and reactive power were measured experimentally at different operating modes of the motor load. Results: as a result of the conducted research, it was found that it is possible to control reactive power sources based on converting the current in the stator circuit of an asynchronous motor into a voltage signal. The experi mental results showed that the stator current value is directly related to the change in the motor load, and the gen erated voltage signal accurately reflects the load state.
Mathematical Model for Calculating Local Over-heating of Stator Winding Bars in Syrdarya TPP Turbogenerators
Relevance: currently, in operating thermal power plants, local overheating of the stator windings of large-capacity turbogenerators is observed due to a sharp increase in the load and clogging of the internal parts of the windings with soot, which leads to a sharp decrease in the useful active power generated. Thus, during the process of local overheating of the stator windings of a turbogenerator, the temperature exceeds the normal operating state, which leads to rapid wear of the insulation layer, thermal deformations, and an increase in additional magnetic and electrical losses. This, in turn, reduces the service life of the turbogenerator, leads to an accident, and can negatively affect the technical and economic performance of the power system. Therefore, the accurate modeling of the heating processes in the stator windings and the early detection of hot zones in the windings is one of the most important conditions for the effective use of power equipment today. Based on the above information, the scientific research work is carried out to prevent local overheating of the stator windings of turbogenerators, to increase the active power generated by them, to organize effective cooling, to increase the active power generated and the efficiency of the turbogenerator. To date, to prevent the clogging of the internal parts of the stator windings of the 320 MW turbogenerator at the Syrdarya thermal power plant, to thoroughly analyze the factors causing it, requires a detailed study of the thermal processes occurring in them. This article considers the issues of preventing local overheating of the stator windings of turbogenerators, using effective cooling and developing a mathematical model, and to increase the active power. Aim: to increase the active power generated and ensure uninterrupted operation based on the mathematical model of local overheating processes of turbogenerator stator winding rods and improving the cooling system. Methods: during the research, methods for preventing local overheating of turbogenerator stator bars were developed, stable operation of the electric power system was ensured, and effective cooling techniques for stator windings were applied. In addition, considering the clogging coefficient of the internal channels of the stator bars, algorithms adapted to the mathematical model were developed to effectively solve the problems of local overheating. Results: based on mathematical modeling of local heating processes of turbogenerator stator coils in thermal power plants, the use of an effective cooling system was studied. As a result, the active power generated increases and the duration of operation is increased.
Results of the study of the stabilization of the output voltage in transient processes when connecting the active load to the asynchronous generator
Relevance: In recent years, many countries around the world have been paying special attention to energy resource conservation, the creation of new alternative energy sources, and the rational use of existing renewable energy sources (RES). Currently, according to the «2020 Key Performance Indicators Review for developed countries, the highest shares of renewable energy usage are observed in Sweden (60,1% of energy consumption), Finland (43,8%), and Latvia (42,1%). The primary sources of energy production in these countries include hydropower plants, wind power plants, and biomass processing» [1]. In this field, particular attention is paid to increasing the requirements for the structural simplicity of power sources for autonomous systems, ease of maintenance, relatively low weight (kVA/kg) and volume, as well as the stability of output parameters under operating conditions. The construction of alternating current generators primarily involves synchronous machines, phase-wound rotor asynchronous machines, and squirrel-cage asynchronous machines. In phase-wound rotor asynchronous machines, integrated frequency converters in the stator and rotor circuits enable effective control of the generator’s excitation process; however, additional external power sources are required for optimal operation control. In squirrel-cage asynchronous machines, the residual magnetization of the magnetic core allows the connection of capacitor banks to the stator windings, providing self-excitation of the generator and stabilization of the output voltage. This capacitor excitation scheme is decentralized, ensuring flexible operation modes of the generator unit under autonomous power supply conditions, which guarantees high efficiency and reliability in wind energy systems. In this article, based on the results of the conducted experiments, oscillograms reflecting the value of the output voltage in transient processes were obtained and analyzed for cases of connecting active loads of various values to an AG with a 4 kW short-circuited rotor. Aim: stabilization of the output voltage in transient processes corresponding to the process of changing the active load of autonomously operating AG and analysis of the results. Methods: methods for analyzing established and transient processes in electric power systems based on experiments were used. Results: autonomous systems must meet requirements such as the simplicity of power supply design, ease of maintenance, relatively small mass (kVA/kg), and volume, as well as the stability of output parameters. Based on the analysis, appropriate proposals will be submitted for the use of AG in renewable energy sources.
Ai-based centralized real-time monitoring and diagnostic framework for lightning risk assessment in large-scale wind power plants
Relevance: Lightning-induced failures significantly reduce operational reliability and safety in large-scale wind power plants worldwide. Objective: This study develops a centralized AI-based monitoring and diagnostic framework for real-time lightning current analysis, multi-source data fusion, anomaly detection, and short-term forecasting in wind turbine systems operating under complex electromagnetic and meteorological conditions. Methods: Multi-source sensor fusion, Bayesian inference, XGBoost prediction, adaptive normalization, and real-time transient signal classification were implemented. Results: The proposed framework reliably distinguished lightning discharges from electromagnetic noise, achieving stable real-time diagnostics and predictive warning performance under experimental operating conditions.
Investigation and minimization of inaccuracies in functional converters using structural modeling methods
Relevance: the development of modern electronics, power conversion technology, and automatic control systems is inextricably linked to the need for fast and accurate processing of continuous signals. Despite comprehensive digitalization, analog functional converters remain indispensable in feedback loops, real-time systems, and complexes operating under severe electromagnetic interference and extreme temperatures, where the use of analog-to-digital/digital-to-analog converters and microprocessors is severely complicated. Pulse-width modulators possess enormous potential for building reliable computing nodes, such as multipliers and dividers. However, their application in modern circuit design is limited by the insufficient development of the general theory regarding instrumental error analysis. Traditional calculation methods fail to explicitly link the physical imperfections of components, such as hysteresis and residual voltages, to the final computational error. Therefore, developing structural modeling methods to identify and eliminate these errors is an urgent task; solving it will significantly increase the accuracy level of industrial electronics. Aim: the purpose of this study is to develop a scientifically grounded methodology for the analysis and structural correction of errors in functional converters based on magnetic-transistor pulse-width modulators using causal-effect graph models. Methods: the study employs a comprehensive analytical approach that includes electrical circuit theory, Boolean algebra, graph theory, and mathematical modeling methods for nonlinear dynamic systems. The primary analytical tool is the causal-effect model, constructed based on the directionality of energy conversion in each circuit section according to the cause-and-effect principle. Additionally, differential calculus methods are utilized to describe the electromagnetic processes of magnetization reversal in ferromagnetic cores exhibiting a rectangular hysteresis loop. Results: a structural graph model of the dividing device was developed, enabling the classification of all error sources into four disjoint sets. It was mathematically proven that the dynamic magnetic field strength of the core induces a linearly increasing multiplicative error, whereas the transistor saturation voltage generates a constant additive error. Strict analytical conditions were established, and formulas for calculating the parameters of auxiliary circuits were derived to achieve complete hardware compensation of the identified errors. This approach was confirmed experimentally, demonstrating a reduction in the total circuit error to 0.2%.
Improving the sustainability of energy consumption of pumping units
Relevance: At present, one of the main and important issues that must be addressed when designing structures and pumping units for machine water lifting systems is ensuring the sustainability of operation with minimal energy consumption of the main structures and equipment of pumping stations. Efficient use of energy resources and sustainable conservation are becoming increasingly important. Overcoming future energy shortages and identifying energy savings potential depend significantly on the correct resolution of this issue. Aim: find the necessary solutions to improve the efficiency of pumping units. Methods: During the study, modern theories and methods for modeling dynamic processes in a water-lifting machine system were used to analyze energy consumption stability. Furthermore, corresponding algorithms were developed to effectively solve frequency control problems. These methods utilize coordinated automation and AI control systems. To determine the maximum efficiency of a variable-speed pump, a variable-speed operation method is used, which changes its flow rate and pressure. Results: Research shows that 30% to 50% of the energy consumed by pumping units can be saved by upgrading the main components of the pumping station or making changes to the control system. Recommendations are given, taking into account the flow profile over time, for optimizing energy consumption for a certain period of operation of pumping units, which are determined by the efficiency value of the pump and motor under their nominal operating conditions, as well as the range of required flow at a certain point in time.
Results of research on output voltage stabilization in transient processes when connecting an active - in-ductive load to an asynchronous generator
Relevance: In a world where demand for electricity is growing year on year, traditional power plants with low utilization rates require natural gas, coal, and petroleum products. Given the need to produce, conserve, and account for the negative impact of these energy resources on the environment, the importance of such power plants has declined in recent years. Climatic conditions are entirely favorable for the large-scale introduction of all types of renewable energy sources (RES) in the Republic of Uzbekistan, which are considered one of the most important areas in the energy sector of the future. As is well known, in connection with this, manufacturing enterprises in the regions, in the course of implementing a number of decrees and resolutions adopted by the President of the Republic and the Cabinet of Ministers in 2024–2026, accelerated the installation of solar panels and the construction of micro-hydroelectric power plants in budgetary institutions and among domestic consumers. In addition, over the past few years, foreign investors have built and commissioned large wind farms. As a result, the country's complete dependence on traditional power plants has been eliminated and the consumption of electricity produced by thermal power plants has been reduced, resulting in significant energy savings. Studies show that wind farms and hydroelectric power plants use synchronous generators (SG) and asynchronous generators (AG) with phase windings and squirrel-cage rotors. Connecting capacitor banks to the stator windings allows the AG to start automatically in the magnetic conductor due to its residual magnetization and to meet requirements such as output voltage stability. The proposed capacitor-based excitation method is decentralized, allowing the generator set to adapt its operating modes in autonomous power supply conditions. In this article, based on the results of the experiment, oscillograms reflecting the output voltage values in the transient processes of AG with a short-circuited rotor with a power of 4 kW were obtained and analyzed. Aim: stabilization of output voltage and analysis of transient processes associated with connecting an active inductive load AG operating in autonomous mode. Methods: methods for analyzing established and transient processes in electric power systems based on experiments were used. Results: autonomous systems must meet requirements such as the simplicity of power supply design, ease of maintenance, relatively small mass (kVA/kg), and volume, as well as the stability of output parameters. Based on the analysis, appropriate proposals will be submitted for the use of AG in renewable energy sources.
Improving the Energy Efficiency of Electric Arc Furnaces and Analysis of High Harmonic Impacts
Relevance: at present, the metallurgical industry is one of the largest consumers of electrical energy, and electric arc furnaces have a significant impact on power supply systems as high-power and nonlinear electrical loads. During the operation of electric arc furnaces, unstable arc burning causes distortion of current and voltage waveforms, leading to the generation of high-order harmonics in electrical networks. These harmonic effects result in deterioration of power quality, increased additional losses, and overheating of transformers, cable lines, and distribution equipment. The limited availability of energy resources, rising electricity tariffs, and stricter energy efficiency requirements imposed on industrial enterprises make the improvement of energy efficiency in electric arc furnaces increasingly important. Reducing electricity consumption not only lowers production costs but also decreases greenhouse gas emissions associated with power generation. At the same time, mitigation of high-order harmonics enhances the reliability of power supply systems and limits adverse impacts on power quality for other consumers. Therefore, research aimed at reducing harmonic effects and optimizing energy losses in electric arc furnaces is of great scientific and practical importance for sustainable industrial development. Aim: the objective of this study is to experimentally identify effective technical and control methods for improving the energy efficiency of electric arc furnaces and reducing their harmonic impact on power supply systems. Methods: the study was carried out based on experimental measurements, spectral analysis of the harmonic content of current and voltage, and comparative analysis of compensation and adaptive control operating modes. Results: it was found that energy performance indicators and harmonic characteristics vary significantly at different operating stages of electric arc furnaces. The application of adaptive electrode control and reactive power compensation improved arc stability and reduced peak current values. As a result, the specific electrical energy consumption per ton of product decreased by 1%. In addition, a reduction in the overall current harmonic distortion was observed, leading to improved power quality. These results contribute
Gis-based big data processing framework forlong-term forecasting of mountain river hydropower resources in multi-purpose hydropower complexes
Relevance: Accurate long-term hydropower forecasting requires intelligent Big Data processing of heterogeneous hydrological and geospatial datasets. Objective: This study develops a GIS-based Big Data processing framework for long-term forecasting of mountain river hydropower resources using distributed computing, statistical preprocessing, IoT monitoring, and geospatial integration technologies to improve forecasting accuracy and operational reliability of multi-purpose hydropower complexes. Methods: PySpark-based distributed processing, Gaussian filtering, log-normal transformation, Poisson and binomial statistical preprocessing methods were applied. Results: The proposed framework improved data reliability to 0,96–0,99, reduced anomalies, and enhanced long-term hydropower forecasting stability and processing efficiency.
Study of Two-Mode Evaporative Coolers in Air Conditioning and Ventilation Systems
Relevance: most regions of Uzbekistan are covered with a hot and dry climate, and partly on the slopes of the valleys there is a hot and humid climate. Direct evaporative coolers are suitable for dry and regenerative indirect evaporative coolers for hot and humid climates. A new two-in-one evaporative cooler is proposed to avoid the use of two different coolers for the same purpose under challenging climate conditions (significant seasonal changes in temperature and humidity), and this study numerically investigates the experimental tests. The proposed cooler takes advantage of both types of evaporative coolers and operates in two modes: direct evaporative cooler for hot and dry climates and regenerative indirect evaporative cooler for hot and humid climates. The operation of both modes (direct and indirect) is explained with the help of diagrams. The effects of duct height and water flow on cooling capacity, wet bulb efficiency, and dew point efficiency are discussed. Aim: the aim of this research work is to introduce a new dual-mode heat and mass exchanger, which is a two-in-one device operating in direct and indirect modes for hot-dry and hot-humid weather conditions, respectively. Methods: differential discretization derived from the conservation of mass and energy in the channels was used using the finite difference method. Results: the performance of the proposed cooler was assessed for five cities of Uzbekistan (Karshi and Termiz with a hot arid climate, Andijan, Namangan and Fergana with a hot humid climate). During the warm months (April to October) and in cities, the suitability of the regimes is assessed using a psychometric table. The research results show that the proposed cooler can be effective and economical to use for regions with mixed climates.
Study of the Effect of Additional Fluidizing Agent Inlets on the Hydrodynamic Parameters of a Spouted Bed
Relevance: drying of high-moisture dispersed materials, especially those prone to agglomeration and the formation of unstable lumps, is one of the most complex heat- and mass-transfer processes. Additional difficulties arise in the processing of polydisperse fiber-forming polymers, which are characterized by deterioration of fluidization conditions and instability of the hydrodynamic regime. In this regard, the search for design solutions that ensure increased particle mixing intensity and an expanded stable operating range of the spouted bed apparatus is of considerable interest. Aim: this study investigated the effect of additional supply of the heat carrier to the peripheral zones of the apparatus on the motion of the solid phase and the main hydrodynamic parameters of the process. Methods: experimental studies were carried out on a spouted bed unit with combined air supply through the lower and side inlets. To assess the mixing structure, an impulse tracer method was used, and the obtained response curves were processed using the method of moments. In addition, spouting curves were analyzed, the operating and limiting pressure drops were determined, the conditions for the onset of stable spouting were established, and the spouting number was calculated for different gas flow distribution modes. Results: it was shown that redistribution of the heat carrier flow in favor of the side inlets leads to a significant intensification of the bed hydrodynamics. In this case, the transition velocity to the spouting regime and the maximum pressure drop decrease, while an increase in the spouting number indicates enhanced circulation exchange of particles within the apparatus. It was established that activation of peripheral flows improves the efficiency of heat carrier utilization, reduces the material processing time, and at the same time maintains the operating pressure drop at an acceptable level. Rational conditions for air flow distribution were determined, providing the most stable operating regime of the unit. Conclusion: the obtained results confirm that the use of spouted bed apparatuses with additional peripheral supply of the heat carrier is a promising direction for drying high-moisture, lump-forming, and polydisperse materials that require intensified hydrodynamic action.
Transition to an independent connection scheme: results of the modernization of the district heating system in Chirchik
Relevance: the transition of Chirchiq to a closed district heating system is critically important for overcoming the energy deficit. The outdated “open” schemes of the 1950s resulted in enormous losses of gas and water, placing a heavy burden on the budget and the environment. In the context of rapid urbanization and population growth to 176 thousand people, the existing infrastructure failed to ensure stable heat supply. The new solution based on Individual Heating Substations (IHS) automates energy distribution, eliminates overheating, and ensures transparency of billing. This represents a strategic step toward Uzbekistan’s energy security, transforming the worn-out housing and services sector into a high-tech and economically efficient industry. The project in Chirchiq became a pilot platform. Its uniqueness for Uzbekistan lies in the separation of heating circuits. Technical water from the boiler house no longer enters residents’ taps. Instead, Individual Heating Substations (IHS) have been installed in the basements of residential buildings. The successful operation of the “Yubileynaya” boiler house and 180 installed IHS units will serve as a foundation for modernizing district heating systems in other regions of Uzbekistan. Aim: to conduct a comprehensive study of the results of modernization of the district heating system in the city of Chirchiq, analyze the transition to a closed scheme, and, based on a comparison of technical data, substantiate the high socio-economic efficiency of the implemented solutions. Methods: a detailed review of technological upgrades at the “Yubileynaya” boiler house and the implementation of Individual Heating Substations (IHS) was carried out. The impact of digital automation on the stability of heat supply and the reduction of the load on urban energy resources was assessed. A comparative analysis of the operational performance of “open” and “closed” heating schemes was conducted, revealing actual savings in natural gas, water, and electricity. Results: the implementation of the district heating modernization project in Chirchiq ensured a significant increase in system reliability and service life through the transition to a closed scheme, pipeline upgrades, and the introduction of automated IHS units. A substantial reduction in heat losses and more efficient resource utilization were achieved, including decreased consumption of water and natural gas as well as reduced atmospheric emissions. As a result, residents received stable heating, clean hot water, and a significantly improved level of living comfort.
Analysis of energy survey of industrial enterprise
Relevance: at present, the issue of efficient and rational use of fuel and energy resources (FER) at industrial enterprises is one of the important factors ensuring the sustainable development of the country's economy. Rising energy prices, expanding production volumes and increasing restrictions on environmental requirements are forcing enterprises to conduct an in-depth analysis of energy consumption and introduce measures aimed at improving energy efficiency. From this point of view, conducting energy research (energy audit) at industrial enterprises today is one of the urgent tasks. Aim: the main purpose of this study is to assess the state of energy use at the enterprise, identify existing energy losses and develop practical measures aimed at improving energy efficiency. Methods: energy audit of the composition of energy consumption at the enterprise. Results: determining the dynamics of energy consumption, determining the period of maximum and minimum loads, assessing the share of reactive energy and developing recommendations for optimizing energy management.
Modern Methods of Inlet Air Cooling for Gas Turbine Units
Relevance: an increase in ambient temperature reduces the air density at the compressor inlet of gas turbine units (GTUs), which leads to a decrease in their power output and energy efficiency. Under conditions of growing electricity demand and the need to improve the efficiency of energy systems, the application of inlet air cooling technologies for gas turbine units becomes particularly relevant, especially for combined cycle power plants. Aim : to conduct a comparative analysis of modern inlet air cooling methods for gas turbine units and determine their impact on performance, energy efficiency, water consumption, and economic indicators of power plant operation. Methods: thermodynamic and techno-economic analyses of various inlet air cooling technologies were applied. Three methods were considered: evaporative cooling, fogging (high-pressure water injection), and absorption cooling. To evaluate water consumption, mass balance equations and water flow calculations for cooling systems and cooling towers were used. Results: the study showed that the use of inlet air cooling systems increases the performance and energy efficiency of gas turbine units. Evaporative cooling increases power output by 5–10% and is characterized by low capital costs, but its effectiveness depends on air humidity. Fogging provides a higher power increase of up to 15–20%, but requires higher water consumption and high-quality water treatment. The absorption chiller demonstrates the greatest increase in power output (up to 20–25%) and operates effectively under various climatic conditions; however, it requires significant capital investment and complex infrastructure.
Technical rearmament of TS-4 “Northern”: transi-tion to combined generation of electric and thermal energy based on gas turbine unit
Relevance: currently, due to the rapid growth of the population, the increase in the number of industrial enterprises, and the expansion of social infrastructure, there is a steady rise in demand for electricity and heat in the country. However, the existing energy generation capacities, in terms of their volume, structure, and technical condition, are not sufficient to fully meet this growing demand. As a result, an imbalance in the fuel and energy system arises, and the power sector becomes one of the limiting factors for the country’s economic development. Therefore, the accelerated growth in electricity consumption requires the widespread implementation of energy-saving technologies, as well as the commissioning of new and efficient generating capacities. In this context, combined heat and power generation (cogeneration) becomes particularly important. This technology is characterized by high energy efficiency and plays a significant role in ensuring sustainable development. Moreover, the introduction of cogeneration systems contributes to improving the environmental situation by reducing the use of traditional energy sources that negatively impact the environment. In this regard, significant reforms are also being implemented in our country. In particular, in accordance with Resolution No. PQ-4388, adopted on July 10, 2019 by Shavkat Mirziyoyev, “On measures for the fundamental improvement and modernization of the heat supply system,” a number of projects have been implemented. Within the framework of this resolution, large-scale reforms on the implementation of cogeneration technologies have been carried out in several cities and districts, particularly at Tashkent CHP-4. This plays an important role in increasing energy efficiency, ensuring rational use of fuel resources, and providing consumers with reliable heat and electricity supply. Based on the above, the study and widespread implementation of cogeneration technologies is one of the most relevant tasks today. Aim: to study the application of cogeneration for improving the efficiency of heat and power generation and ensuring rational fuel use. Methods: large-scale implementation of cogeneration and combined production of thermal and electrical energy. Results: cogeneration contributes to sustainable development through high energy efficiency, reduces heat losses, and has a positive impact on the environment.
Study of methods for assessing the efficiency of photovoltaic modules and devices
Relevance: this scientific article scientifically analyzes the methods for assessing the efficiency of photovoltaic modules and devices. The development of solar energy utilization technologies plays an important role in the energy supply system. Therefore, determining, analyzing and optimizing the efficiency of photovoltaic modules is one of the current issues. The article examines in detail the physical foundations of the photovoltaic effect, the structure of solar cells, the volt-ampere characteristic, and methods for assessing efficiency in laboratory and real operating conditions. Modern monitoring systems and efficiency improvement technologies are also analyzed. Methods for assessing the efficiency of photovoltaic modules and devices are scientifically analyzed. The development of solar energy utilization technologies plays an important role in the energy supply system. Therefore, determining, analyzing and optimizing the efficiency of photovoltaic modules is one of the current issues. The article examines in detail the physical foundations of the photovoltaic effect, the structure of solar cells, the volt-ampere characteristic, and methods for assessing efficiency in laboratory and real operating conditions. Modern monitoring systems and efficiency improvement technologies are also analyzed. The share of renewable energy sources in the Republic of Uzbekistan is growing rapidly, especially as a result of the large-scale integration of solar power plants into the power system, new problems arise in real-time control of the system frequency and voltage. Since solar energy is inherently variable and its power is difficult to predict, the issue of maintaining a balance between production and load, in particular, assessing the efficiency of photovoltaic modules and devices, is becoming increasingly relevant. This article analyzes the impact of photovoltaic modules and devices operating in conjunction with a solar power plant on the efficiency of Aim: the study of methods for assessing the efficiency of energy sources, in particular photovoltaic modules and devices of solar power plants, aims to identify problems arising from their integration into power systems, analyze their impact on the system, and develop methods to ensure its stability. Methods: in order to evaluate and analyze the efficiency of photovoltaic modules and devices in power systems, modern theories of solar power plants, photovoltaic modules and devices, and nonlinear mathematical programming methods were used. Results: the results of the assessment of the impact of increasing the efficiency of solar power plants, photovoltaic modules and devices are presented.
Ecological water treatment technology in thermal power plants
Relevance: the globalization of environmental problems requires new ways of thinking. The reliability and efficiency of CHP plants largely depend on the quality of feed water. The discharge of chemical reagents into water bodies is intensifying ecological problems. Aim: to reduce water treatment costs at thermal power plants, optimize reagent and resin consumption, and demonstrate the effectiveness of the “EKOTEX” IBE technology implementation. Methods: comparative analysis of thermal and chemical desalination technologies, study of practical operation results and technical-economic indicators of “EKOTEX” IBE units. Results: “EKOTEX” IBE technology confirmed ecological and economic advantages over chemical desalination. The distillate cost is twice lower than conventional methods, with a project payback period of 2-3 years.
Influence of direct contact heat exchange on the vacuum level in horizontal condensers
Relevance: the efficient operation of condensers used in industrial enterprises is directly dependent on the internal pressure level. The lower the pressure inside the condenser (the higher the vacuum), the faster and more complete the condensation process occurs. In the winter season, the cooling water temperature is around 10–15 ℃, which allows maintaining the pressure inside the condenser up to 4 kPa. However, in the summer season, when the cooling water temperature rises to 30–40 ℃, the pressure inside the condenser increases to 7 kPa and higher. Such pressure changes lead to incomplete steam condensation, a decrease in the efficiency of the technological process, and an increase in additional energy consumption. Since the radical reconstruction of existing condensers requires large capital investments, studying the possibilities of reducing the pressure inside the condenser using simple and economical methods is an urgent scientific and practical problem. Aim: to develop the theoretical foundations of the method of additional water spray into the upper part of a horizontal shell-and-tube surface condenser to reduce pressure (improve vacuum) when the cooling water temperature rises, to quantitatively assess its efficiency, and to determine its optimal parameters. Methods: The study developed a mathematical model of heat transfer processes using the example of a horizontal condenser consisting of 168 tubes (outer diameter 28 mm, inner diameter 25 mm, wall thickness 1,5 mm, length 1 m, steam inlet window 400×600 mm, two-pass). The heat transfer surface area of the condenser based on the outer diameter is 14,78 m². The Nusselt equation was used for surface condensation, heat transfer laws for turbulent flow were applied for the cooling water inside the tubes, and the droplet flow theory was used for the direct contact zone. The relationship between the pressure and saturation temperature of water vapor was modeled using the Antoine equation. The change in pressure inside the condenser was analyzed for various flow rates of the additionally sprayed water. Results: the calculations showed the following results. Winter mode (cooling water temperature 10 ℃, condenser pressure 4 kPa). The condenser is capable of condensing 0,224 kg/s (806 kg/h) of steam. The required cooling water flow rate is 16,2 kg/s (58,3 m³/h). The outlet cooling water temperature is 18,5 ℃, and the mean logarithmic temperature difference is 12,8 ℃. Summer mode (cooling water temperature 30 ℃, same steam flow rate 0,224 kg/s). The pressure inside the condenser increases from 4 kPa to 9,85 kPa (an increase of 5,85 kPa). The steam condensation temperature rises from 29 ℃ to 45,8 ℃. The outlet cooling water temperature reaches 36,2 ℃. When applying the additional water spray method. The optimal additional water flow rate was found to be in the range of 200–250 kg/h (0,0556–0,0694 kg/s). At this flow rate, the thermal power transferred due to direct contact is 151,5 kW. By spraying additional water, the pressure inside the condenser can be reduced from 9,85 kPa to 7,05 kPa (an improvement of 2,8 kPa). The steam temperature decreases from 45,8 ℃ to 39,2℃. The volumetric heat transfer coefficient for direct contact condensation is in the range of 110,4 kW/(m³∙K), which is 6–8 times higher than that of traditional surface condensation. With an average droplet diameter of 1 mm, the number of droplets formed per second is 123,6 thousand, and their total heat exchange surface area is 0,45–0,52 m²/s. The power required for the pump of the additional water spray system is only 0,0277 kW, indicating the high energy efficiency of the method. Efficiency analysis. Due to additional water spraying, the pressure inside the condenser decreases by 25%. Approximately 16–18 kg/h of additional water is required for every 0,1 kPa reduction in pressure. Increasing the additional water flow rate above 400 kg/h is not advisable, as the pressure reduction slows down and water consumption increases.
Analysis of modern methods of utilization of flue gas heat in thermal power plants
Relevance: this study is devoted to the analysis of modern methods of utilization of flue gas heat in thermal power plants (TPPs). The low efficiency of thermal power plants is currently leading to a trend in the world energy systems to switch from steam turbine plants to combined steam-gas plants. However, one of the pressing issues facing the world energy sector is to continue scientific research aimed at modernizing and renovating existing steam turbine thermal power plants and increasing their efficiency. Aim: to identify methods for reducing heat losses with flue gases of steam turbine plants, develop thermal schemes, and evaluate their effectiveness. Methods: during the research, more than 30 scientific articles published in the Scopus and Web of Science databases worldwide between 2010 and 2024 were reviewed. Organic Rankine Cycle (ORC), absorption heat pump systems (AHP/OAHP), low-pressure economizers (LPE), heat pipe heat exchangers (HPHE), and thermoelectric generators (TEG) were analyzed as the main technologies. Results: based on the research, OAIN systems allow recovering up to 80-95% of the available and latent heat in flue gas, while the ORT system can generate power from 220 W to 15 MW with a thermal efficiency of 8-12%. It was determined that the unused heat potential in large thermal power plants in Uzbekistan (Syrdarya, Tashkent, Navoi, Talimarjon) is 120-250 MW. The highest economic performance was recorded for absorption heat pump systems with a payback period of 1.4-2.5 years. This study provides a scientific basis for the introduction of flue gas heat utilization technologies to increase energy efficiency and reduce CO2 emissions in Uzbekistan.
The impact of water spraying on condenser vacuum and hydraulic resistance
Relevance: additional water spraying systems used to improve vacuum in industrial condensers are typically installed at the condenser inlet section. The sprayed water droplets begin to interact with the steam flow already in the inlet zone, creating local hydraulic resistance. Determining the magnitude of this local resistance and its impact on the overall vacuum is an important scientific and practical task. Aim: to accurately calculate the local hydraulic resistance arising from water droplets sprayed by nozzles installed at the condenser inlet section and to assess its effect on the condenser vacuum. Methods: The study analyzed the two-phase flow in the inlet section of a horizontal condenser with 168 tubes (steam inlet area 0.24 m², flow cross-sectional area between tubes 0.13 m²). The steam flow rate was 806 kg/h = 0.224 kg/s, pressure 4 kPa, density 0.028 kg/m³, inlet velocity 33.3 m/s. The additional water flow rate was 279 kg/h (0.0775 kg/s), nozzle pressure 0.2 MPa (2.0 bar), droplet velocity 14.0 m/s, droplet diameter 1.0 mm. Droplet concentration, aerodynamic drag force, and turbulent mixing resistance were calculated. The variation of resistance was analyzed depending on parameter changes (water flow rate, droplet diameter, steam velocity, nozzle pressure, scheme type). Results: the local hydraulic resistance in the inlet section is 1.83 Pa (0.00183 kPa). This is only 0.44% of the total two-phase resistance (0.413 kPa). The effect on vacuum is 0.014 mmHg. When the water flow rate increases from 100 kg/h to 300 kg/h, the inlet resistance increases from 0.66 Pa to 1.96 Pa. When the droplet diameter increases from 0.5 mm to 1.5 mm, the resistance decreases from 2.05 Pa to 1.73 Pa. When the steam velocity increases from 25 m/s to 40 m/s, the resistance increases from 1.10 Pa to 2.46 Pa. When the nozzle pressure increases from 0.1 MPa to 0.4 MPa, the resistance slightly decreases from 1.88 Pa to 1.76 Pa. Among the scheme types, the highest resistance is observed in the counter-flow scheme relative to the steam flow (2.05 Pa), and the lowest in the co-current flow scheme (1.83 Pa). Although the counter-flow scheme slightly increases resistance, it improves heat transfer and increases condensation efficiency. Analyses show that water droplets absorb the kinetic energy of the steam, sharply reducing its volume, which positively affects the overall hydraulic conductivity of the device.
Developing General Motion, External Influence Modules and 5D Device Integration
Background: The global industrial automation market reached $91,1 billion in 2025, yet software integration of five-dimensional (5D) motion platforms remains critically inefficient. Protocol fragmentation accounts for 62% of integration project failures across the sector, representing $3,2 billion in annual engineering productivity losses. Objective: To develop and validate a modular three-layer architecture-comprising a General Motion Module (GMM), External Influence Modules (EIM), and a 5D Device Integration Adapter (5D-DIA)-and to assess its effect on positional accuracy, synchronization precision, and integration efficiency across heterogeneous multi-axis motion systems. Methods: Experiments were conducted on a six-servo electromechanical motion platform operating at 1 000 Hz under FPGA clock control. A jerk-limited trajectory planning kernel, a nonlinear Kalman-based sensor fusion layer, and a 5×5 cross-axis coupling compensation matrix were implemented and tested across 2 400 controlled motion sequences on three commercially distinct device families. Results: The full-stack architecture reduced cross-axis positional error from 1,83 mm to 0,21 mm (−88,5%) and elevated multisensory synchronization precision from 82,4% to 96,1%. Mean closed-loop latency was 0,74 ms. Integration project time decreased by 58% and cross-platform motion repeatability improved by 3,2.