RELEVANCE of this study lies in the establishment of technological indicators of emissions of benz(a)pyrene into the atmosphere to assess the degree of negative impact of energy enterprises on the environment and the development on this basis of primary (air protection) measures, inventory of emissions ofpollutants, collection and preparation of initial environmental information for the effective implementation of the principles of technological regulation of emissions in the domestic thermal power industry. THE

   PURPOSE. The technological features of the formation of polycyclic aromatic hydrocarbons, in particular benz(a)pyrene, in the furnaces of power boilers burning organic fuel are considered.

   The regime factors significantly influencing the intensity of the formation of benz(a)pyrene as the most carcinogenic and mutagenic impurity in
flue gases have been determined. As part of the implementation of the principles of technological rationing of polluting marker substances, energy enterprises should determine the mass emission of highly toxic combustion products to improve the environmental performance of combustion processes and establish technological emission indicators.

   METHODS. Determination of mass emissions of polycyclic aromatic hydrocarbons was carried out using methods of mathematical statistics, processing of environmental information, system analysis of data and processing of the results obtained.

   RESULTS. Analytical expressions have been developed to determine the content of benz(a)pyrene in the combustion products of coal and anthracite. The values of mass emissions of benz(a)pyrene for inventory and justification of technological rationing of carcinogenic and mutagenic substances at energy enterprises have been determined.

   CONCLUSION. The results obtained are recommended to be used for a preliminary assessment of the content of benz(a)pyrene in the flue gases of boilers at power plants at the stage of collecting and preparing information for the introduction of technological rationing of highly toxic substances and the assessment of technological emission indicators.

   RELEVANCE. Maintaining the required level of energy security (ES) and reliability of fuel and energy supply is one of the priority tasks in the management of the energy sector. In the functioning of the fuel and energy complex various threats are possible, which can lead to the violation of the reliability of fuel and energy supply and the emergence of shortages of
various types of energy resources. To assess the level of energy security, approaches are considered to form a mathematical model of the FEC, which combines all sectors of the energy sector. Despite the trends of transition to low-carbon energy sources associated with energy transformation, thermal power plants remain one of the main sources of heat and electricity.
Due to the ability to generate large amounts of heat only thermal power plants can be a source of centralized energy supply of large territories. In this regard, when modeling the fuel and energy complex, it is necessary to develop mathematical models of TPPs, which will correctly reflect the technological processes that affect the reliability of energy supply.

   OBJECT. Development of mathematical models of interaction of electric power, heat supply and fuel systems within the framework of thermal power plants designed to study energy security and reliability of fuel and energy supply.

   METHODS. Mathematical modeling of fuel consumption dependences on electrical and thermal load at thermal power plants is used as methods. To obtain analytical dependencies, the least squares approximation of the consumption characteristics of thermal power plants was carried out.

   RESULTS. As part of the work, analytical dependences of fuel consumption on thermal and electrical load for various types of thermal units were obtained. For all considered steam turbines, linear dependences of the
amount of heat supplied to the turbine on its load (electrical and / or heating depending on the type of turbine) were obtained. For boilers, an approximation of the dependence of efficiency on thermal load was carried out. According to the results of the approximation, a linear dependence is assumed. For gas turbine installations, an approximation of the dependence of the efficiency on the load was carried out, according to the results of which a second-order polynomial was obtained.

   CONCLUSION. The paper investigates the problem of mathematical modeling of the interconnected operation of fuel, heat and power and electric power systems within the framework of the functioning of the energy sector. Analytical dependences are obtained for different types of generating equipment, including boilers, steam turbines and gas turbine installations. The obtained dependences are necessary for the analysis of energy security and reliability offuel and energy supply. The models of thermal power plants presented in the paper are the most suitable for the analysis of energy security and reliability of fuel and power supply, as they provide the necessary accuracy of calculations and take into account the specifics of various generating equipment, without dropping to the level of microparameters.

   RELEVANCE. At present, unstressed systems for launching high-voltage electric motors have been increasingly used. These systems limit the values of starting currents as well as eliminate alternating oscillations of engine electromagnetic torque.
   THE PURPOSE. Development of measures to improve the technical resource of electrical equipment of powerful irrigation pumping stations based on the use of soft start systems for high-voltage electric motors.

   METHODS. In the course of the study, methods for analyzing the technological processes of a pumping station, methods for mathematical and computer modeling of an electric drive were used. RESULTS. Computer models have been developed to study the regime characteristics of asynchronous and synchronous electric drives of pumping stations with direct and soft start of electric motors. A shockless start-up system for high-voltage electric motors of irrigation pumping stations of the first lift based on a current inverter is proposed.

   CONCLUSION. The reliability and durability of electrical equipment depends primarily on the technical resource, which is determined by a number of factors. The main factors influencing the technical life of the electrical equipment of large irrigation pumping stations are the transient modes that occur when the pumping units are started. The soft start system of high-voltage electric motors of irrigation pumping stations proposed in this article makes it possible to eliminate the negative impact of transient conditions on the operation of electrical equipment and, thereby, increase the technical resource and reliability of the power supply system of the pumping station as a whole.

   RELEVANCE. Servo drives operate with a law of change of the setting action unknown in advance and provide reproduction of this law by the output coordinate. Servo drives find application in robotic and mechatronic systems, machine tools, systems of automatic control and remote transmission of information, radar stations, guidance units, etc. The operation of servo
drives often proceeds in conditions of instability parameters and characteristics elements of the electric drive. Corrective devices synthesized by classical methods of automatic control theory cannot cope with providing the specified accuracy of reproduction of the input signal and the required quality of transients.

   THE PURPOSE. In this regard, an important and urgent task is the synthesis of an active correction system with a non-stationary controller that provides the required quality and accuracy of the control process due to the coefficient self-tuning algorithm.
   METHODS. When solving this problem, methods for identifying parameters based on the gradient algorithm and numerical integration of the object of study dynamics equations, implemented by means of the MatLab software environment, were used.

   RESULTS. The paper solves the problem of synthesizing the self-tuning algorithm for the coefficients of the servo drive corrective device based on the identification approach. The parameters are identified by a searchless gradient algorithm while minimizing the discrepancy between the object of study and its inverse model, as well as restoring the coefficients of differential equations using integration and the corresponding computational procedures. An servo drive with negative position feedback is tuned to the modular optimum with a proportional controller whose coefficients are completely determined by the parameters to be identified. The self-tuning algorithm consists in calculating the correction factor of the non-stationary P-controller and forming a multiplicative channel of the active correction closed loop.

   CONCLUSION. The simulation of the electric drive in the MatLab software environment showed high accuracy and quickness of the process identifying parameters in a wide range of their change. When forming an active correction contour, a necessary requirement is to distinguish between the identification cycle and the self-tuning cycle. This makes it possible to avoid singular perturbations and reduce resonant facts during the operation of a parametrically invariant electric drive. The developed method of active correction with a priori known and unchanged structure of the object model of study makes it possible to maintain the required accuracy and quality of the operation of the electric drive under conditions of parametric disturbances with permissible deviations of accuracy and quality indicators. Implementation of the method does not require additional equipment, organization of special test signals, significant computational costs. The method of synthesizing a parametrically invariant electric drive can be used to develop robust control systems for non-stationary objects, including when the hypothesis of quasi-stationarity is not fulfilled.

   RELEVANCE. The reliability of power supply to consumers depends on the reliability of all elements of the power supply system, including relay protection and automation devices (RZiA). Knowing the current values of the reliability indicators of various devices makes it possible to take them into account when designing RPA, choosing more reliable devices, identifying shortcomings in RPA and performing work to eliminate them.
   THE PURPOSE. Due to the lack of open data on the current values of reliability indicators of relay protection and automation devices (RPA) of electric networks of 10-110 kV, the question of their determination on the example of power systems of various regions is relevant.

   METHODS. The authors present and analyze official statistical data on the number of emergency failures, false and correct actuations of relay protection and automation devices in the electric grid organization - branch of PJSC «Rosseti Center» – «Ore lenergo» for 2013-2021.

   RESULTS. In the course of the study, numerical values of the following reliability indicators of relay protection and automation devices were determined: the failure rate and the frequency of excessive triggering. Relay
protection and automation devices, for which reliability indicators have been determined, are used to implement arc protection, maximum current protection, automatic re-activation, differential protection of buses and transformer, transverse directional differential protection, gas protection of transformer, differential-phase protection.

   CONCLUSION. The values of the failure flow for different types of relays and microprocessor devices of the RPA are established, for example, for an electromechanical relay of the DZT-11 type used to implement differential protection of transformers with a higher voltage of 110 kV, the failure flow is 0,2 year^-1/100 pcs., and the frequency of excessive triggering is 22,22 year^-1/100 pcs. Conclusions are drawn about the need for measures to regulate the settings and maintenance of devices of various types.

   RELEVANCE. An urgent task is to improve the reliability and quality of power supply. Very often, failures in operation are caused by damage to overhead and cable lines. Traditionally, a fairly large number of violations occur in the share of electrical distribution networks. For the reliable functioning of power systems and uninterrupted power supply to consumers, it is necessary to identify and eliminate faults in a short time to minimize damage. Thus, a method for efficient, accurate and reliable fault location is needed for both utility companies and consumers. To solve this problem, it is necessary to quickly obtain information about the state of the distribution eclectic network.

   THE PURPOSE. Reducing the time to search for a fault location in electrical networks, reducing damage from downtime for undersupply of electricity by analyzing existing methods for determining the location of faults on a power transmission line and developing a method for its prompt detection in electrical networks.

   METHODS. The basis of this method is a preliminary theoretical calculation of short-circuit currents in various sections of a power line. Based on the values obtained as a result of the calculation, the measured values of the short-circuit currents are compared with these values, on the basis of which the location of the line damage is determined. An algorithm for searching the left and right boundaries of the short-circuit current value in an ordered array of statistical data has been developed.

   RESULTS. A method for quickly determining the location of a short circuit is proposed, which is based on the use of a data array of theoretically calculated short circuit currents. The presented algorithm is able to accurately determine the coordinates of the short circuit in electrical networks.

   CONCLUSION. The proposed method for determining the location of damage to the power line allows you to increase the efficiency of determining the point of a short circuit and thereby reduce the time to eliminate the accident, and therefore, economic losses from undersupply of electricity.
The basis of this method is a preliminary theoretical calculation of short-circuit currents in various sections of a power line. Due to the subsequent comparison of the measured values of short-circuit currents with the values of the calculated values, the location of the damage to the power line is determined. The presented algorithm is designed to accurately determine the
coordinates of the short circuit location, which can significantly reduce the search time and improve the accuracy of determining the fault location in the range from 100 to 150 m, regardless of the length of the power line, which significantly reduces the time to search for damage at the same time as solving the problem of reducing downtime , as well as minimizing damage both for guaranteeing suppliers represented by electric grid companies, and for consumers represented by industrial and agricultural enterprises.

   RELEVANCE. Any device loses its performance over time, Power transformers too. The problems of overheating and insulation are the main influencing factors to the operation status of power transformers. Thus, the study is of high relevance and applied demand, because the heating ofpower transformer elements, especially in the territory of the Syrian Arab Republic, can reach 46 °C. Monitoring the state ofpower transformers is of decisive importance in the study of reliability and safety indicators in the power system. Thermal stress is one of the main parameters to be controlled. Sharp fluctuations in the temperature of the transformer winding, oil, insulating medium, etc. affect the operating conditions, sen’ice life and safety of transformers.

   PURPUSE. Determination of the type of functional dependences of the heating temperature of windings and oil ofpower transformers on their loading. METHODS. Determination of the type of functional dependences of the change in the temperature of the windings and oil of power transformers using the methods of statistical data processing, approximating functions and assessing their reliability.

   RESULTS. Approximating functions of the main temperature parameters ofpower transformer elements have been developed - a function of the temperature of the average overheating of the winding above the oil temperature; function of the temperature of the average overheating of the oil above the temperature of the cooling air; oil superheat temperature function above the cooling air temperature; superheat function of the hottest spot above the cooling air temperature. The coefficients of determination of the obtained temperature functions of the average overheating of the winding and the average approximation error are determined. As a result of the research, it was found that the polynomial function is the most reliable. The developed dependencies can be used for practical application to assess and analyze the heating temperature of oil and transformer windings with a known load, as well as to control the operating modes of electrical equipment and consumers of electrical energy in power supply systems.

   RELEVANCE. One of the most important expected effects of digitalization of objects of the power grid complex of the Russian Federation is to increase the level of reliability of its functioning. In this regard, research and development in this direction is undoubtedly relevant.
   THE PURPOSE. To propose a mathematical model for monitoring dangerous developing defects in power oil-filled transformers, this would meet the properties of predictability and adaptability. Based on the model, to develop a decision-making algorithm for long-term reliable operation of
transformers.

   METHODS: Methods of statistical pattern recognition theory, correlation analysis and Bayesian classification will be used to solve the problems to ensure high reliability of diagnostic assessments, validity and effectiveness of operational solutions.

   RESULTS. A predictive model was obtained and verified in the form of a correlation function of a sign of a faulty state of a transformer from the values of its electrical load. An event tree has been formed that restores the causal relationship between the result of monitoring the transformer, the defect sign and the operational decision being made. Based on the event tree and diagnostic evaluation criteria, a control algorithm is implemented, with the help of which calculations are performed confirming the effectiveness of the proposed approach.

   CONCLUSION. The possibility of effective application of the developed defect recognition model and operational control algorithm as tools of industrial technology of the Internet of Things is illustrated, in particular, when organizing remote diagnostic monitoring of oil-filled transformer equipment at substations of the distribution grid area.

   RELEVANCE. Recently, along with the initial scope of synchronized vector measurements (synchrophasor) technology associated with Wide Area Measurement System (WAMS), more and more attention is paid to expanding the scope of this technology. Digital substations are one of the places for generating synchrophasor signals, at the same time, synchrophasor data are proposed to be used for the purposes of relay protection and automation at the digital substations itself, which will facilitate the construction of centralized relay protection systems at the substation.

   THE PURPOSE. Consider the use of synchrophasor technologies at a digital substation of the fourth type, as a replacement for Sampled Values (SV) signals. Consider additions to the standard set of synchrophasor signals necessary for the operation of various relay protections at a digital substation. Perform an analysis of the accuracy of calculating the synchrophasor when the frequency of the controlled current and voltage changes relative to the nominal value, when higher harmonics appear in the measured signal. Develop a pre-computation technique for relay protection algorithms.

   METHODS. When solving the problem, the method of calculating the total measurement error of the synchrophasor TVE (Total Vector Error) was used - a value that characterizes the deviation of the amplitude and phase of the measured vector from their specified values.

   CONCLUSION. The use of synchrophasor signals with the necessary additions for the operation of relay protection reduces the load on the digital network of the digital substation, simplifies the operation of relay protection algorithms. Calculations have shown that the measurement errors of synchrophasor do not go beyond the specified parameters. The proposed methods of precomputation allow to speed up the work of relay protection algorithms.

   The purpose of this work is to improve the method of vibration control of a power transformer through the use offractal analysis of the amplitude-time signal.

   Fractal analysis of the amplitude-time characteristics will allow to quantify the degree of «indentation» of the vibration signal of the transformer associated with a defect. For a quantitative assessment, the fractal analysis coefficient (FAC) was introduced based on the determination of the fractal dimension by the Hausdorff-Besikovich method. To test the developed method, a non-contact laser measuring and diagnostic complex (LCMC) with developed software based on LabVIEW, ImageJ and Python was used. Experimental studies of the transformer TSZ 16 were carried out using the developed method and LCIK. The CFA of the windings and magnetic circuit of the transformer under study, the level of technical condition for the controlled elements of the transformer are determined.

   METHODS. The improved method of control makes it possible to increase the accuracy of control of a power transformer during its operation under voltage, which makes it possible to switch from a planned system of transformer repairs to a system for taking repairs according to the current technical condition.
   RESULTS. The improved method of vibration control was tested using the developed non­ contact LCIK, the level of technical condition of the power transformer under voltage was determined.
   CONCLUSION. An improved method of vibration control makes it possible to determine the level of technical condition of an energized power transformer with the possibility of automatically obtaining a decision on the technical condition, as well as to use statistical methods for processing and analyzing the signals received from the transformer.

   RELEVANCE. Among the various methods for assessing the technical condition of power equipment, vibration diagnostics occupies an important place. Therefore, improving the quality of hardware for vibration diagnostics is currently extremely important.

   THE PURPOSE. To develop a vibration sensor with a new principle of operation for systems of technical vibration diagnostics of power equipment, as well as to theoretically substantiate the performance of the proposed sensor.

   METHODS. When solving the set goal, the main provisions of the theory of vibration diagnostics were applied.

   RESULTS. A design of the vibration acceleration sensor has been developed, the peculiarity of which is that it is excited by means of constructive coupling capacitors, the first electrode of which is made in the form of a thin-walled metal split cylinder, the role of the second electrodes is performed by the lower row of the winding of each measuring coil, and the function of the inertial element is performed by a screen made in the form of a metal ring fixed on a suspension in the form of a membrane. Based on the electrical equivalent circuit of the sensor, a theoretical substantiation of its operability and efficiency was made. Variants of circuit solutions for the primary and secondary measuring transducers of the measuring device for vibration diagnostics systems have been developed. The primary measuring transducer contains directly a vibration displacement sensor, a sinusoidal voltage source, an input differential measuring amplifier and an analog filter containing a narrow-band filter, a broadband amplifier and a buffer amplifier. The secondary measuring transducer contains a quadrature detector of information signals, an output buffer amplifier and a quadrature reference voltage driver. A block diagram of the hardware solution for the vibration acceleration registration system is also proposed.

   CONCLUSION. The developed sensor has improved output characteristics and can be used not only for vibration control of power equipment, but also for measuring mechanical vibrations in technical diagnostic systems of various other machines and mechanisms, as well as for tasks of spectral seismic exploration.

   THE RELEVANCE. Phenols are one of the main pollutants of the aquatic environment and have a harmful effect on the human body. Therefore, their determination today is an urgent problem.

   The purpose of this work is to determine the content of phenols in an aqueous medium by gas chromatographic method using various sorption materials.

   To do this, it is necessary to consider some features of the gas chromatographic method for monitoring the content of phenols in an aqueous medium using various sorption materials. Based on a detailed literature review to show that phenols and their derivatives are highly toxic substances, have low values of MPC standards, ha\’e a negative impact on the human body, which necessitates their control in the aquatic environment. METHODS. To determine phenols in an aqueous medium, the experimental part of the work was carried out on a Crystallux-4000M gas-liquid chromatograph with a flame ionization detector and nozzle columns filled with various sorbents, as which polyethylene glvcol-1500, SE-30 and arsenated polyethylene glycol PEG(As) were used.

   RESULTS. For gas chromatographic separation of phenols and their derivatives, sorption materials of various physicochemical nature were used. It has been established that the most optimal sorbent, which separates almost all phenols and their derivatives, is polyoxyethylene bis arsenate, the molecule of which contains two arsenvl groups capable of intermolecular interactions with the analyzed sorbates.

   CONCLUSION. An experimental study of the phenol content in an aqueous medium using a gas-liquid chromatograph Crystallux-4000M was carried out. The characteristics of the retention of phenols on sorption materials  of different physicochemical nature are determined. It is shown that the most complete separation of the individual components of phenol derivatives is carried out on a sorbent prepared on the basis of polyoxyethylene bis arsenate, which is explained by the presence in the structure of its molecule of non-white electron pairs of oxygen atoms capable of intermolecular interactions with the hydroxyl group of phenols. The linear dependence of the logarithm of the relative volume of phenols on their dipole moments and refractive index is established. A deviation from this dependence is obsen’ed for phenols having functional substituents in the ortho-position of the benzene ring. This can be explained by the electronic effect? which leads to steric difficulties during intermolecular interaction in the sorbent - sorbate system. Based on the theoretical studies carried out, it was possible to completely separate the individual components of phenols, especially those with close boiling points. The obtained data were tested in practice when monitoring the content of phenols in the silt drains of the Volga river. This technique of gas chromatographic analysis can be used in the system of ecological monitoring of aquatic ecosystems.

   RELEVANCE of the work lies in establishing the relationship between industrial injuries, when online monitoring in the electric grid company, with the influence of hazardous production factors, since the latter is the cause of accidents, Accidents and other occupational hazards of employees and loss of health of employees. For this purpose it is necessary to develop methods of causes, nature and application of systems of prevention and localization of accidents, accidents.

   THE PURPOSE. The article discusses possible solutions to an urgent problem - analysis and determination of the causes of industrial injuries and occupational morbidity in the electric power industry and assessment of occupational risks of workers and loss of health of workers at hazardous production facilities, as well as the lack of attention of employers to the reconstruction and modernization of production, the development and
application of warning systems and localization of accidents, accidents, preventive work, control over the state of the production environment and compliance with sanitary and hygienic requirements, which will generally lead to industrial safety.

   METHODS. The main research method was the development and application of systems for the prevention and localization of accidents, accidents, preventive work, monitoring the state of the production environment and compliance with sanitary and hygienic requirements.

   RESULTS. The methods of online monitoring of the parameters of working conditions are considered, while the authors carried out special studies of the complex influence of adverse environmental factors and working conditions, which make it possible to unambiguously identify priority etiological factors, as well as sources of impact on the human environment.

   CONCLUSION. Attention is drawn to the prospects of the adverse impact ofproduction factors under conditions of intensive technogenic pollution of the environment. The authors believe that in order to increase the effectiveness of socio-hvgienic monitoring in the analysis and forecasting of the impact of the environment on the health of the population, it is necessary to develop objective criteria for assessing both the natural and industrial environment in order to study significant changes and develop measures to improve and improve working conditions and means management of production safety, adaptive capabilities of the body and the prevention of environmental pathology.

   The study of heat exchange processes using numerical modeling in software systems is a complex operation. In the course of conducting numerical studies on heat transfer, it is necessary to adequately adjust the solution of the problem. To do this, the most suitable turbulence models are selected, grid models are created, and boundary conditions are set. Obtaining reliable results of numerical simulation of heat exchange processes directly depends
on setting the correct parameters that need to be analyzed initially, , 4 s  a result of the work on the analysis of the necessary parameters, an adequate solution to the problem can be obtained.

   THE PURPOSE. To evaluate the influence of turbulence models on the heat transfer process and to select the most suitable model for numerical simulation of the external flow around the heated pipe. To study the influence of quantitative criteria of the grid model on the accuracy and convergence of the numerical calculation solution.

   METHODS. During the numerical simulation, the finite element method was used in the ANSYS Fluent software package.

   RESULTS. In the course of the study, the most suitable turbulence model was selected to solve the problem of external flow around the heated pipe. A grid model is constructed taking into account the features of the problem under consideration. The errors are determined depending on the quantitative criteria of the grid model.

   CONCLUSION. Numerical studies have made it possible to give a comparative assessment for pipes with different fins. The results obtained showed that replacing pipes with straight fins with spiral ones allows increasing the heat transfer intensity up to 40 %.

   RELEVANCE. Vertical cone diffusers are used in various technical applications: heat exchangers, gas cleaning units, boilers, industrial furnaces, dryers, ventilation devices, nozzle systems and others. For their efficient operation, it is necessary to ensure a uniform supply of the working medium to the device, which is determined by the characteristics of the flow in the
diffuser. Thus, the study of the aerodynamics of technological devices with conical diffusers is an urgent task for gas-dynamic improvement and the search for ways to control flow characteristics.

   THE PURPOSE. To establish the evolution of the velocity field along the height of the cylindrical part of the diffuser for different configurations of the supply tubes, and also to determine the magnitude of the change in the intensity of turbulence along the height of the diffuser under different initial conditions based on experimental data on the instantaneous values of the air flow velocity.

   METHODS. Measurement of instantaneous values of air flow velocity is carried out using a constant temperature hot-wire anemometer. The article provides data on velocity fields and turbulence intensity along the height and along the diameter of the cylindrical part of the diffuser when air is supplied through tubes of different configurations. Feed tubes with cross sections in the form of a circle, a square and an equilateral triangle were used.

   RESULTS. The article provides a detailed description of the experimental stand (including key geometric dimensions), instrumentation and measurement system, and data processing techniques. The ranges of changes in the initial conditions for the experiments are presented. A comparison of the aeromechanical characteristics of flows in a vertical diffuser when air is
supplied through different tube configurations is carried out. CONCLUSION. It is shown that in the diffuser there is a drop in the average velocity upstream, which is typical for all configurations of the supply tubes. It has been established that profiled tubes influence the shape of the velocity field. It was found that the values of turbulence intensity vary from 0.05 to 0.39 (the highest values were typical when air was supplied through profiled tubes). It is shown that the intensity of turbulence has its maximum values at a height of 300-350 mm, which is typical for all investigated tube configurations.