The relevance of the research topic stems from the high damageability of electrical networks (EN) during electricity transmission. Preventive assessment of possible damages, which lead to significant losses due to under-supply of electricity, constitutes an essential component in developing emergency response plans at electric grid companies in the Russian Federation.

   The aim of the study is to develop prognostic characteristics of potential emergency outages in the electrical networks of the Rostovenergo Branch of Rosseti South PJSC based on accident data for these networks from 2018 – 2024.

   A substantial portion of the study involves analyzing the number of damages and their causes. It was found that the total number of outages over the study period amounted to 42,042, resulting in economic losses exceeding 664,986 thousand rubles. Numerical analysis methods, mathematical statistics methods, general scientific research methods, and the properties and capabilities of the MATLAB graphics editor and Excel spreadsheets served as the methodological basis. Various failure forecasting models were reviewed, with a comparative analysis of their applicability for predicting failures due to multiple causes, accounting for the seasonal component. The study results indicate that the following models can be used for forecasting emergency outages in the studied electrical networks: the trend model — for all months of the year except September; the trend-seasonal model — for all months except March, August, October, and December; and the autoregressive model — for October only. According to the derived exponential relationship, 3,718 emergency outages are projected in the studied networks in 2025, 5 % fewer than in 2024.

   The relevance of this study is driven by the need to enhance the resilience and efficiency of energy complexes in Central Asia under climate change conditions and the growing demand for clean energy.

   The work analyzes the potential of solar, wind, and hydropower; the structure of the energy balance structure in the countries in the region; as well as the institutional and technological barriers limiting the implementation of green energy. Despite the significant potential of renewable energy sources, their systemic consideration in the regional context, as well as their integration with power system parameters remains an important scientific challenge.

   The object of this research is the energy complexes of the Central Asian countries that utilize renewable energy sources.

   The aim of the study is a comprehensive assessment of the impact of renewable energy development on the functioning of energy complexes in Central Asia and their contribution to strengthening energy security.

   The methods included statistical and trend analysis of time series from 2010 to 2024, a comparative analysis of implemented projects, as well as a review of national strategies and international programs in the field of renewable energy development.

  Additionally, elements of structural analysis of power systems and methods for systematizing climate data are applied. The results show that the expansion of solar, wind, and hydropower usage leads to a significant reduction in greenhouse gas emissions and enhances the resilience of power systems. The growing share of renewables contributes to reducing dependence on fossil fuels and improving the environmental situation. A comparison of the results with international studies confirms the validity of the methodology and the soundness of the conclusions. The study formulates practical recommendations for modernizing the energy complexes in Central Asia and emphasizes the importance of investment and regional cooperation in the development of renewable energy.

   The preventive maintenance system (PMS) is the primary and regulatorily mandated approach to the maintenance of hydroelectric power plants and power enterprises, aimed at ensuring the reliable and safe operation of primary equipment [1]. The calendar-based nature of the PMS makes it possible to maintain the required level of operational reliability; however, it does not fully take into account the actual technical condition of individual hydropower unit components during the inter-repair period. Under changing operating conditions and individual operational characteristics, this may result either in the performance of excessive maintenance interventions or in delayed detection of developing defects, increasing the risk of unplanned repairs. A diagnostic approach is presented, based on the analysis of indirect operational parameters of a hydropower unit recorded by standard automated process control systems (APCS). The proposed algorithm identifies parameter deviations from their characteristic values at early stages of defect development and forms diagnostic indications deterioration in the technical condition of critical hydropower unit components. The effectiveness and informativeness of the approach are demonstrated through the analysis of operational data from hydropower units at a hydroelectric power plant. It is shown that the use of diagnostic algorithms of this class does not require the installation of additional measuring equipment and can be implemented at operating hydroelectric power plants without significant capital expenditures. The application of the proposed approach expands the possibilities for assessing the actual technical condition of equipment, improves the validity of repair planning, promotes the transition to a more flexible and adaptive maintenance model oriented toward real operational indicators and risk-based equipment life management, and enhances the overall industrial safety of the plant.

   During the development of offshore oil and gas resources, natural gas hydrates have become a serious hidden threat to the safe operation of deepwater pipelines. Under prolonged exposure to low temperatures and high pressures, hydrate plugs easily form in pipelines, directly reducing throughput and creating significant challenges for the development and operation of the energy industry. To address this issue, the proposed optimized solution is a closed-loop system for pipeline cleaning, monitoring, analysis, and feedback during the cleaning process. While pipeline cleaning operations are performed at the inlet, a built-in processing module simultaneously collects pipeline operational data and transmits it in real time. After in-depth analysis, the system generates detailed reports and targeted research proposals, while historical data is stored for subsequent retrospective analysis. This solution improves efficiency through implementing real-time monitoring technology to accurately determine pipeline status, upgrading the data collection module of the pipeline cleaning equipment to improve the completeness and timeliness of data collection, and improving data analysis and storage methods to ensure the scientific rigor and security of data processing. Ultimately, this enables dynamic blockage tracking and synchronous pipeline condition assessment. It significantly improves the overall efficiency of deepwater field development, operation, and maintenance, providing a practical industry solution to the hydrate blockage problem with significant theoretical value and practical importance.

   The development of Horizontal Directional Drilling (HDD) technology has led to a new trenchless method for installing district heating networks using casing pipes. The regulatory framework for the designing and constructing such HDD pipelines is evolving but still contains several gaps. One notable gap is the absence of a standardized methodology for thermal insulation calculation. A methodology for calculating thermal insulation of district heating pipelines with casing installed by HDD has been developed. It is based on the algorithm for calculating linear heat losses in direct buried pipelines, as specified in the Code of Practice SP 61.13330.2012 "Thermal Insulation of Equipment and Pipelines". The list of components contributing to total thermal resistance has been refined, and calculation formulas have been proposed to account for the specific features of trenchless casing installation, as well as the products and materials used. For calculating the thermal resistance of soil, an approximate formula is justified; its error is negligible within the typical ranges of burial depth and pipeline diameter for trenchless installations. New practical dependencies have been established for the thermal resistance of polymer pipes as a function of material thermal conductivity and either the Standard Dimension Ratio (SDR) or pipe series (S). It is shown that polymer pipes and casing tubes with identical SDR or S values, made of the same material, have the same thermal resistance regardless of diameter, which reduces computational effort. A straightforward approach is proposed for determining the linear heat flux, taking into account the influence of the thermal field from multiple adjacent pipelines. An example is provided for the thermal insulation calculation for a four-pipe district heating network installed using the trenchless casing method. The developed methodology can serve as a reference supplement to the Code of Practice SP 61.13330.2012 "Thermal Insulation of Equipment and Pipelines".

   High specific electricity costs in remote regions, together with logistical challenges associated with fuel delivery and increasing environmental constraints, are accelerating the shift toward localized, low-carbon autonomous energy systems. These systems increasingly incorporate renewable energy sources (RES). An algorithm for determining the optimal configuration of a combined power supply system based on microhydropower plants (micro-HPPs) is presented. Such systems provide generation and storage capabilities intended to meet the needs of decentralized consumers. To identify technically and economically viable configurations of an autonomous energy source, an analytical review of domestic and international research was conducted. The findings informed the development of fundamental electrical and hydraulic layouts of the system. A preliminary assessment of key hydro unit parameters was performed, and the potential integration of photovoltaic (PV) modules into the generation structure was examined. Three representative system architectures are proposed. The first configuration involves a micro-HPP without energy storage. The second is a micro pumped-storage power plant (micro-PSPP) incorporating one or two reservoirs for energy accumulation. The third represents a hybrid micro-PSPP that combines storage functionality with PV generation for energy recovery into the system. Alongside these configurations, methodological approaches were established for determining reservoir energy capacity, selecting suitable hydraulic machines, and structuring the logic of energy-flow management. A prototype test bench was also developed to support model-based experimental studies. The proposed concept demonstrates technical feasibility and promising economic performance under a range of typical operating conditions. The methodological framework and the test-bench design provide a foundation for further engineering development and for scaling the proposed solution.

   The operation mode of a water-to-water heater of a heating system is considered when it is independently connected to an external district heating network, ensuring reliable heat supply, stability of the hydraulic regime of the system and the necessary comfort in the premises. A mathematical model has been constructed and investigated that describes the variable operating modes of the heaters of the heating system during the heating period under the conditions of the implementation of this scheme and takes into account the change in the heat transfer coefficient of the unit and the mean temperature difference of the heat carriers in it. Based on the results of calculations using a computer program that implements an iterative algorithm based on the specified model, an analysis is provided of the behavior of the heat transfer coefficient of the heater during the cold period due to changes in the physical properties of water as a coolant when its temperature is regulated depending on current weather conditions. It is shown that at the beginning and end of the heating season, this coefficient decreases by about 20 percent compared to the mode of the coldest five-day period, but due to the non-linearity of the expression for the logarithmic mean temperature difference in the heat exchanger, its actual heat transfer under these conditions, when using a typical temperature schedule, is, on the contrary, about 20 percent higher than the required heat demand of the building. A solution to this problem is proposed through adjusting the temperature schedule downwards in both the supply and return pipelines at intermediate values of the outside temperature. The presentation is illustrated with numerical and graphical examples.

   The paper addresses the issues of design and numerical simulation of a bi-rotative centripetal low-flow turbine with a rotating nozzle guide vane system, intended for application in compact low-power gas-turbine power units. The turbine design is based on the principles implemented in low-flow turbines of the LPI design, which are characterized by high energy intensity, compactness, and favorable gas-dynamic performance under low working-fluid flow rates. Based on an analysis of experimental data and the design features of LPI turbines, a methodology for profiling the flow path of a bi-rotative stage has been developed, ensuring coordinated operation of the rotating nozzle guide vane system and the impeller under prescribed inlet flow conditions. A detailed three-dimensional geometric model of the flow path was constructed, followed by numerical simulations performed using the ANSYS CFX software package. The calculations were carried out over a wide range of turbine pressure ratios, πт =2,0…6,0, and rotor rotational speeds (nBCA, nPK = 13,000…30,000 rpm) employing the SST (Shear Stress Transport) turbulence model. The study analyzes the fields of Mach number, velocity, total pressure, and total temperature, as well as the characteristics of power distribution and energy exchange between the rotors. It is shown that the centripetal bi-rotative configuration provides a more uniform outlet parameter distribution, reduced losses, and an increased internal efficiency compared with conventional single-stage turbines. The obtained results confirm the feasibility of applying the developed turbine in advanced low-power gas-turbine and hybrid energy systems operating near nominal conditions.

   Objective: To develop a methodology for the comprehensive diagnostics of the cooling system and mechanical integrity of windings based on the joint spectral analysis of synchronized time series of the vertical temperature profile in SF6 gas and winding vibration.

   Methods: The primary method is multifrequency spectral analysis. For thermal processes, an adapted model of advective-diffusive heat transfer is used, allowing the estimation of the SF6 flow velocity and effective thermal diffusivity coefficient from the relationship between the amplitude ratio and phase shift of vertically spaced sensors. For analyzing mechanical condition, the use of a miniature fiber-optic vibration sensor installed in the inter-winding space is proposed.

   Results: Based on the conducted experiments, diagnostic features were identified. It was established that a decrease in the SF6 flow velocity leads to an increase in the amplitude ratio of the low-frequency (1.1×10^-4 Hz) temperature component. Weakening of the winding clamping manifests as an almost twofold increase in the normalized vibration amplitude at 100 Hz, while local deformation manifests in the appearance of new resonant peaks. High coherence between slow temperature oscillations and vibration was revealed.

   Conclusions: A comprehensive approach is proposed, which enhances diagnostic reliability through the synergy of thermal and mechanical process analysis and the formation of digital condition "fingerprints". The method is intended for integration into predictive maintenance systems.