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E-Journal N1(61)2024

"PROBLEMS of the REGIONAL ENERGETICS (https://doi.org/10.52254/1857-0070.2024.1-61)"

CONTENTS

1	Synthesis of the Spatial Arrangement of Magnetic Field Sensors for Active Shielding of the Magnetic Field of Overhead Power Lines Authors: Kuznetsov B.I.1, Nikitina T.B.2, Bovdui I.V.1, Voloshko O.V.1, Kolomiets V.V.2, Kobylianskyi B.B.2 1 Anatolii Pidhornyi Institute of Mechanical Engineering Problems of the National Academy of Sciences of Ukraine Kharkiv, Ukraine 2 Educational scientific professional pedagogical Institute Ukrainian Engineering Pedagogical Academy, Bakhmut, Ukraine
	Abstract: The purpose of the work is to develop a method for synthesizing the spatial arrangement and angular position of magnetic field sensors to ensure maximum efficiency of robust active cleanliness system of magnetic field generated by overhead power lines and reducing synthesized system sensiti-vity to initial uncertainties and changes in system parameters during operation. To achieve this goal spatial location coordinates and angular position of all magnetic field sensors and controllers gains vector for compensating windings are determined. The synthesis of spatial arrangement and angular position of magnetic field sensors are reduced to solving a minimax vector optimization problem, in which the vector objective function calculated are based on Biot-Savart’s law. The solution of the minimax vector optimization problem has been calculated based on optimization algorithms by a multiswarm of particles from Pareto-optimal solutions taking into account binary preference relations. The most important results obtained based on the developed synthesis method are values of effectiveness of robust active cleanliness system of magnetic field generated by different overhead power lines with synthesized spatial arrangement and angular position of magnetic field sensors obtained in theoretical and experimental research process. The significance of the results lies in the fact that practical recommendations are given for the reasonable choice of spatial location and angular position of magnetic field sensors, the spatial arrangement of shielding windings of a robust magnetic field shielding system for various characteristics of power lines. Possibility of initial magnetic field reducing to sanitary standards level has been shown.
	Keywords: overhead power transmission line, magnetic field, research. DOI: https://doi.org/10.52254/1857-0070.2024.1-61.01
2	Calculation of Magnetic Losses with Non-Uniform Distribution of Magnetic Induction in the Stator Tooth of a Switched Reluctance Motor Authors: Bibik O.V., Mazurenko L.I., Popovych О.М., Golovan I.V., Shykhnenko M.O. Institute of Electrodynamics of the National Academy of Sciences of Ukraine Kyiv, Ukraine
	Abstract: . The aim of this study is to investigate and determine the effect of accounting for the non-uniform distribution of magnetic induction (by detailing the stator tooth model) on the calculation results of magnetic losses in the stator teeth of a switched reluctance motor in quasi-steady-state modes. To achieve this goal, dependencies of phase flux linkage, electromagnetic torque of the motor, and additionally, dependencies of the root mean square values of magnetic inductions in stator tooth elements on the rotor angle and current have been determined using the finite element method. An investigation of dynamic modes of the switched reluctance motor based on an improved simulation model has been conducted at various values of constant load torque. Dependencies of magnetic inductions over time for each stator tooth element for the studied quasi-steady-state operating modes have been obtained. Magnetic losses have been calculated, taking into account the maxima of the temporal dependencies of root mean square values of magnetic induction in stator tooth elements. The most important outcome is a quantitative assessment of the influence of the non-uniform distribution of magnetic induction on the calculated value of magnetic losses based on the detailing of the stator tooth model in the operational modes of the switched reluctance motor compared to the traditional approach. The significance of the work lies in developing an approach to refining the calculation of magnetic losses by considering local saturation in the magnetic circuit during the operation of the switched reluctance motor.
	Keywords: switched reluctance motor, magnetic losses, detailing of stator teeth, magnetic induction, quasi-static mode. DOI: https://doi.org/10.52254/1857-0070.2024.1-61.02
3	Effect of Motor Shaft Eccentricity on the Performance of a High-Speed Magnetic Fluid Sealer Authors: Nesterov S.A. and Baklanov V.D. Ivanovo State Power Engineering University, Ivanovo, Russian Federation
	Abstract: The objective of the study is to develop recommendations for accounting during the design stage and the feasibility of operating a magnetic fluid seal with a significant eccentricity of the rotating shaft relative to stationary pole attachments. This goal is achieved through conducted experi-mental research, the selection of necessary equations, boundary conditions, assumptions, and physical properties of the magnetic fluid when constructing a numerical mathematical model of the working gap of the magnetic fluid seal. The most important results of the study include ob-tained and analyzed distributions of the magnetic field, velocity field, and pressure in the mag-netic fluid, as well as the evaluation results of the impact of absolute and relative shaft misa-lignment in the magnetic fluid seal, centrifugal forces arising during shaft rotation, on the re-tained pressure drop by the seal. A significant reduction in the retained pressure drop occurs at an eccentricity of up to 40% of the working gap, and with further increases in eccentricity, the rate of pressure drop reduction slows down. The significance of the results lies in the potential utilization of the provided numerical model, as well as the outcomes of physical and mathemati-cal experiments, in the development of a magnetic fluid seal operating with significant misa-lignment between the rotating shaft and the housing. The dimensionless dependencies obtained allow for consideration, during the design stage, of the reduction in retained pressure drop with shaft eccentricity, taking into account the magnitude of the working gap, magnetic induction, and linear velocity.
	Keywords: magnetic fluid, magnetic fluid seal, eccentricity, pressure drop, numerical modeling. DOI: https://doi.org/10.52254/1857-0070.2024.1-61.03
4	Universal Continuous Model of Active Power Factor Correctors Authors: Amelina M., Amelin S., Yakimenko I. Branch of the National Research University Moscow Power Engineering Institute in Smolensk Russian Federation
	Abstract: The purpose of the work is to develop continuous mathematical models of power factor correctors for switch-mode power supplies. The models are designed to solve optimization problems aimed at increasing the energy efficiency of these devices. This goal was achieved by developing a universal continuous averaged model of switch-mode voltage converters, which are an integral part of any active power factor corrector. State-space averaging method was proposed for constructing such a universal model. It has been shown that such a model adequately reproduces the processes in any of the main types of DC-DC voltage converters. The possibility of constructing a mathematical model of an active power factor corrector based on the proposed universal model of a DC-DC voltage converter is substantiated. The features of the structures of active power factor correctors for switching power supplies are considered and the problems that arise when studying their energy efficiency are shown. By simulation in the time domain with using the constructed model, diagrams of transients of the power factor corrector during load and primary network voltage disturbances are obtained. The most important result is the creation of a universal continuous mathematical model of switching voltage regulators. This model, unlike previously proposed models, is suitable for use in the analysis, modeling and design of any power factor correctors without the need to modify it in each specific case. The significance of the results obtained lies in accelerating the design process of active power factor correctors built on the basis of any type of pulsed DC-DC voltage converters. The developed model is intended for use in the Micro-Cap electronic circuit analysis program. However, since it is ultimately a software module in the SPICE language, this model can be used in many circuit analysis programs that support this language.
	Keywords: switch-mode power supply, power factor corrector, averaged continuous nonlinear model, pulse-width modulator, state-space averaging method, continuous conduction mode, discontinuous conduction mode. DOI: https://doi.org/10.52254/1857-0070.2024.1-61.04
5	Improved Clamped Z-Source Converter with Optimized Maximum Power Point Tracker for Hybrid Renewable Energy Systems Based Energy Management System Authors: Saranya M.1, Giftson S. G.2 1Arasu Engineering College, Kumbakonam, Tamilnadu, India. 2Sir Issac Newton College of Engineering and Technology, Nagapattinam, Tamilnadu, India.
	Abstract: In light of the intermittent and seasonal nature of wind and solar energy, electrical systems are becoming more problematic to operate. The purpose of the work is to establish an energy storage system that helps to minimize such operational challenges, which are essential to improve grid stability and reliability. The tasks solved in the article to achieve the given goal are the following: incorporating an energy management system with the aid of improved converter and optimized maximum power point (MPPT) for (Photovoltaic) PV and PMSG (permanent magnet synchronous generator) based wind system. On comparing with conventional Z-source converters, a novel improved clamped Z-source converter, which is utilized in this work has high efficiency with low THD and it has the capacity to protect electrical circuits against damage caused by short circuits, overcurrent and overvoltage. The Pulse Width Modulation (PWM) rectifier is implemented to convert AC-DC supply obtained from the PMSG wind system. Firefly optimization with an aid of Radial Basis Function Neural Network (RBFNN) technique is employed as an MPPT system for extracting optimal power from photovoltaic system. The excess energy obtained from the hybrid sources are stored in the battery and it is controlled by the recurrent neural network (RNN) with the bidirectional converter. The overall developed system is executed in MATLAB software and the most important outcomes are demonstrated in terms of high efficiency with 91.2%, high tracking efficiency of 98.54% and reduced THD of 2.45% respectively. The significance of results obtained in this research lies in the advancement of renewable energy integration technologies. By overcoming the challenges associated with intermittent energy sources, the developed system contributes to the improvement of grid stability and reliability.
	Keywords: synchronous generator maximum power point, improved clamped Z-source converter, firefly optimized neural network, recurrent neural network. DOI: https://doi.org/10.52254/1857-0070.2024.1-61.05
6	Capacitive Sensor for Monitoring the Condition of Suspended High-Voltage Insulation Authors: Andreenkov E.S., Shunaev S.A. Smolensk branch of National Research University "MPEI" Smolensk, Russian Federation
	Abstract: The purpose of the work is to develop the design of a sensor for monitoring the condition of high-voltage power lines suspended insulation. To achieve this goal, a diagnostic criterion was selected, the operating principle and design of the insulation monitoring sensor were determined. As a diagnostic criterion is considered a changing of voltage on the insulator plate due to a change in the distribution of electrical potential on the insulators, caused of damage in the insu-lators string. For the diagnostic system implementation was adopted a sensor based on a capaci-tive divider. The calculations confirm the possibility of registration a damaged element in a insu-lators string by getting of voltage change at the sensors output. The calculation results were veri-fied by modeling in the Multisim software. The parameters of the sensor were calculated, cor-rectness of it is confirmed by the results of laboratory measurements of the new insulators plate capacitances, as well as insulators destroyed as a result of operation. The most important results of the research are the selection of the optimal diagnostic criterion and researching of the pro-posed design sensor effectiveness for assessing the suspended insulation condition. The signifi-cance of the results obtained lies in the fact that the developed design of a sensor allows one to obtain prompt information about the presence of damage in the insulation. The use of the pro-posed sensor design will make possible creation a continuous diagnostic system and identify damage at an early stage, which will ensure timely maintenance.
	Keywords: insulator, diagnostics, capacitive divider, capacitor, sensor. DOI: https://doi.org/10.52254/1857-0070.2024.1-61.06
7	Absorption Chiller Efficiency Increasing at Waste Heat Recovery of Co-generation Plants using a Vapor Compression Chiller as a Backup Cold Source Authors: Kornilev A.N., Baranenko A.V., Malinina O.S. Educational Center "Energy-Efficient Engineering Systems" ITMO University St. Petersburg, Russian Federation
	Abstract: Cooling efficiency in a trigeneration cycles is one of the most frequently problems. A single-stage hot water absorption chiller is a universal solution for the gas engine waste heat utilization. However, trigeneration centers exploitation experience shows the need for a more detailed tech-nical and economic analysis to achieve maximum efficiency of the three-generation cycle. The purpose of this article is to substantiate the use of two-stage absorption cycles increasing the uti-lization rate of waste gas heat. The study presents the results of assessing the efficiency of using energy resources on the example of a three-generation center with more than 14 years of exploi-tation experience, including two single-stage absorption chillers (Q0= 0.65 MW each) and a chiller with a screw compressor (Q0= 0.8 MW). A comparison of actual energy consumption with designed indicators was carried out. The influence of external and internal factors on the efficiency of heat recovery from a gas engine in single-stage absorption refrigeration machines with a water-heated generator is considered. The dependence of the change in the average annu-al cooling coefficient during the calendar year was obtained. Based on the study, proposals were formulated to improve the energy efficiency of refrigeration supply, giving an increase in refrig-eration capacity of 6.1% with a commensurate reduction in the load on the screw chiller. The option of using a combined two-stage cycle chiller (type 2) under similar operating conditions showed a COP=1.43, which provides savings of 67.45 MWh of electricity or 5.4%, on an annu-alized basis (assuming only waste heat is used). Additional advantages of such a cycle include increased accuracy and stability of maintaining the water temperature at the absorption chiller evaporator due to more flexible adjustment of the temperature of the lithium bromide solution in the high-temperature generator.
	Keywords: energy efficiency, three-generation cycle, absorption lithium bromide single-stage chiller, heat utilization. DOI: https://doi.org/10.52254/1857-0070.2024.1-61.07
8	Application of a Three-Stage Procedure for Extracting a Small-Sized Anchor Object on a Noisy Image Authors: Sotnikov O.M.1, Vorobiov O.M.2, Udovenko S.G.3, Kobzev I.V.3, Vlasiuk V.V.4, Kurbatov A.A.4 1Kharkiv National University of the Air Force named after Ivan Kozhedub, Kharkiv, Ukraine. 2National University of Defense, Kyiv, Ukraine. 3Kharkiv National Economic University named after Semen Kuznets, Kharkiv, Ukraine. 4Kyiv Institute of the National Guard of Ukraine, Kyiv, Ukraine.
	Abstract: The purpose of the article is to develop a three-stage procedure for identifying an anchor object in a noisy current image. This goal is achieved by determining the sampling threshold levels at which the greatest similarity of the compared images is ensured; development of a procedure for refining the maximum of the decision function by quantizing the current image. The solution to the first problem is based on the formation of a correlation field of radio brightness temperatures and the choice of a sampling threshold. It is proposed to use the cross-correlation coefficient as a criterion for the degree of image matching. The effectiveness of the procedure for selecting a fragment of a reference image is assessed based on the criterion of the probability of selecting a fragment of a reference image. It is shown that image noise can lead to a decrease in the probability of selecting a fragment of a reference image, down to 0.4. It is proposed to refine the maximum of the decision function based on the iteration method. The most significant results are the obtained dependences of the probability of choosing a fragment of the reference image on the threshold value and the signal-to-noise ratio, as well as the analytical relation for the asymptote of this dependence. The novelty of the work lies in the fact that the procedure for forming the decisive function has been further developed. This will significantly improve the operating efficiency of unmanned aerial vehicles, especially in conditions of interference.
	Keywords: unmanned aerial vehicle, three-stage procedure for forming the decision function, image discretization and quantization, probability of choosing a fragment of the reference image. DOI: https://doi.org/10.52254/1857-0070.2024.1-61.08
9	Address Energy Delivery Technologies Based on The Hybrid Electrodynamic Processes Authors: Burdo O.G.1, Terziev S.G.2, Sirotyuk I.V.1, Molchanov M.Yu.1 1Odesa National University of Technology, Odesa, Ukraine 2PRJSC “ENNI FOODS”, Odesa, Ukraine
	Abstract: An effective tool has been identified for transferring technologies for processing food raw materials onto the rails of the nano-eco-industry — these are hybrid processes in electrodynamic devices. The aim of the work is a comprehensive study of hybrid processes in microwave electrodynamic systems. To achieve the goal, an experimental stand was created, which made it possible to visually confirm the effects of mechanical diffusion and establish the influence of key parameters on the kinetics and energy of hybrid processes. The working section — a model of a capillary-porous structure — was a bundle of calibrated glass tubes. When processing experimental data, the dependences of the influence of field power, channel diameter, temperature, and beam orientation on the kinetics and energy of the hybrid process were obtained. The most significant result of the work is the use of certain modes of organizing hybrid processes to control the extraction process in electrodynamic devices of three types: volumetric, film and circulation. Tests of these structures confirmed the formulated hypotheses of the formation of a hybrid process. The importance of the work lies in the fact that it is shown that the effect of mechanical diffusion is most powerfully manifested in electrodynamic extractors of the circulation type and energy consumption in electrodynamic extractors of the volumetric type is 1.4 times lower, film extractors are 1.5 times lower, and circulation type ones are 1.9 times lower, than in devices of traditional design.
	Keywords: electrodynamic apparatuses, energy technologies, hybrid processes, extraction, evaporation, drying, mathematical and experimental modeling. DOI: https://doi.org/10.52254/1857-0070.2024.1-61.09
10	Optimization of Mixed Fluid Cascade Natural Gas Liquefaction Plant Feed Stream Pressure Authors: 1Ikonnikova A. Yu.,1,2 Baranov A. Yu.,1 Kravchenko D. V., 1 Seredenko E. S. 1ITMO University 2Scientific and Production Enterprise «KRYON» Saint Petersburg, Russian Federation
	Abstract: This paper presents the results of a study on optimising the feed stream pressure of the Mixed Fluid Cascade natural gas liquefaction cycle. The objective is to optimise the pressure of the feed stream to distribute heat effectively over the cooling stages and reduce the energy cost of the cycle. To achieve the goal, the following tasks have been done: constructing the mathemati-cal model of the cycle, performing the calculation experiment for different values of the feed stream pressure to determine energy characteristic values, and determining the optimal values of feed stream pressure. The flow characteristics of the working substances in the cycle are deter-mined based on the Peng–Robinson–Stryjek–Vera equations of state and Benedict–Webb–Rubin. The mass flow of the working substance is calculated for each cycle's stage heat load, at both constant and different values of the working point temperatures. The distribution of heat load for liquefying 1 kg of natural gas by stages is displayed, and achievable working point tem-peratures of the feed flow are determined. The energy consumed by the compressor units and the amount of compression heat dissipated are calculated. The study's main finding is that the optimal feed pressure in the Mixed Fluid Cascade cycle is higher than the standard pressure. The significance of the obtained results lies in the significant reduction of energy costs of the Mixed Fluid Cascade cycle at a feed stream pressure of 13 MPa.
	Keywords: liquefied natural gas, mainline gas, energy efficiency, pressure increase. DOI: https://doi.org/10.52254/1857-0070.2024.1-61.10
11	Energy Efficiency of the Extrusion Process and its Effect on Output of Biogas during the Fermentation of Maize and Rape Straw Authors: Zablodskiy M.1, Klendiy P.2, Dudar O.3, Babak D. 1 1National University of Life and Environmental Sciences of Ukraine, Kyiv, Ukraine 2 Separated subdivision "Berezhany Agrotechnical Institute" National University of Life and Environmental Sciences of Ukraine, Berezhany, Ukraine 3Separated structural subdivision “Berezhany professional college of National University of Life and Environmental Sciences of Ukraine” Berezhany, Ukraine
	Abstract: The purpose of the research is determining the influence of pre-treatment by extrusion of rape and maize straw on the output of biogas and the energy efficient mode of the extrusion process. The set goal is achieved by solving the following problems: pre-treatment of rape and maize straw by grinding and various versions of extrusion; carrying out experimental researches of the fermentation of rape and maize straw in the mesophilic mode of fermentation for 42 days; carrying out numerical modeling to determine the power inputs on the process of extrusion during change the frequency rotation of screw conveyer of the extruder. The most significant results: it was experimentally proven that the output of biogas from rape and maize straw increases when the size of their particles is reduced to a certain value, which is reached after 2-times extrusion, and further reduction of the size of the particles does not give a positive effect and, vice versa, reduces gas release. Extrusion provides not only grinding, but also thermo-baro processing, which additionally grinds lignin-cellulosic raw material. It was determined that the energy efficient mode of operation, the necessary level of pressure and temperature in the die, which exclude the burning of organic raw materials, is ensured at the rotation frequency of screw conveyer of the extruder at 110 r/pm. The significance of the obtained results is that the extrusion with the proposed technological and mode parameters of the extruder can be used as an effective method of pre-treatment of lignin-cellulosic raw material to increase the productivity of bioreactors and biogas output.
	Keywords: substrate, biogas, extrusion, energy efficiency, simulation model. DOI: https://doi.org/10.52254/1857-0070.2024.1-61.11