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  Problemele energeticii regionale

E-Journal N1(53)2022



1 Mechanical Power of DC Motors with Polygarmonic Power Supply
Authors: Kovalov V.1, Kovalova Yu.2, Shcherbak I.2 1 National Technical University of Ukraine "Kharkiv Politechnic Institute" 2 O.M. Beketov National University of Urban Economy in Kharkiv Kharkiv, Ukraine
  Abstract: The aim of the work is to develop a method for determining the mechanical power of DC mo-tors when they are powered by semiconductor converters, since the harmonic components of the armature current do not create a torque on the shaft. This means that at the nominal electric power of the motor, it is necessary to reduce the mechanical power to ensure the nominal tem-perature regime of the armature winding. The aim is achieved by solving the problem of deter-mining the dependence of the mechanical power of the motor on the armature current pulsations factor, the value of which depends on the control parameter of the thyristor or transistor con-verter, on the inductance of the armature circuit and the load current. As a result, it was pro-posed to express the dependence of the mechanical power in terms of the allowable mechanical load factor, which, in turn, depends on the armature current pulsations factor. The method is as follows: 1) on a computer model determine the armature current pulsations factor; 2) determine the allowable mechanical load factor and the allowable mechanical power. The novelty of the work lies in the fact that the expression for determining the allowable mechanical load of DC motors with polyharmonic power has been further developed, which, unlike the known ones, contains the square of the armature current pulsations factor. An example of the practical use of the proposed method for calculating the allowable mechanical power of DC motor when pow-ered by single-phase thyristor rectifier.
  Keywords: DC motor, mechanical power, load factor, factor of pulse current.
2 Reactive Power Compensation in a Hybrid Renewable Energy System through Fuzzy Based Boost Converter
Authors: Sathish Ch.1, ChidambramI A.,1 Manikandan M.2 1Annamalai University, India 2Jyothishmathi Institute of Technology and Science, India
  Abstract: The reactive power compensation is essential during hybrid grid connected system, because the overall power factor of the power systems is reduced due to DC energy fed to the grid using electronic energy inverters. Increased load on the grid due to poor power factor triggers losses in the grid. The main objective of the work related to control the Reactive Power flow in grid connected Hybrid Renewable Energy System (PV-wind-battery). The objectives of the work were achieved by satisfying the load demand, injecting the reactive power from hybrid sources to the grid. First, the proposed technique with fuzzy based boost converter is implemented. It reduced power conversion stages, decreases the losses compared to existing Hybrid Grid-connected systems. The most significant result of the work is the conclusion that the fuzzy based boost converter should increase the Maximum power from solar PV Panel, The speed control of wind energy system is control by speed controller-fuzzy rule, and it created with low speed to high speed. The significance of the obtained results is that the used methodology allowed maximum energy utilized by hybrid renewable energy system to grid. The reactive power is maintained at zero level in order to ensure the unity power factor operation. But rather significantly enhances the small voltage fluctuation in the grid. In addition, to reduces the current total harmonic distortion to 1.9 %, which is good lower than the requirement for network operation. The proposed method is verified using MATLAB/Simulink. The simulation results were supported experimentally.
  Keywords: hybrid renewable energy system, photovoltaic system, fuzzy based boost converter,total harmonic distortion.
3 Elaboration of the Calculation Algorithm for the Load Diagram of a Thermoelectric Generator that Applies the Temperature Dependent Thermoelectric Layer Properties
Authors: Golubev R.O., Stolyarov S.P. Sanct-Petersburg State Marine Technical University Sanct-Petersburg, Russian Federation
  Abstract: The aim of the work is the development of the algorithm for the working parameters calculation of a marine waste heat thermoelectric generator, where the thermoelectric layer properties are considered as temperature dependent. The marine thermoelectric generator must have an exten-sive operational profile that includes a number of modes with a different power demand and different magnitudes of the waste heat parameters. The working mode alteration involves the change in the thermoelectric properties. To achieve the goal a mathematical model was offered for a load diagram calculation. The load diagram represents the generator parameters alteration with respect to the load current change. The most important result was the proposed new order of calculation that differs from the present models with offered variables, an approach to con-structional thermal resistances application and a specific electrical power implementation. Mean temperature and load factor are taken as variables with the load factor being accepted as a rela-tion between the electrical resistances of a load and a generator. Constructional thermal re-sistances were combined into two complex parameters – the thermal resistances of a hot and cold sides. The significance of the obtained results is determined by shaping a versatile approach to the generator`s working parameters calculation. The methodology is independent of the scheme of the calculated generator`s thermal resistances, which could be transformed into the complex parameters. The specific power calculation allows defining the performance per a cross-sectional unit area. The optimal selection of variables reduces the computational time.
  Keywords: load diagram, thermoelectric generator, thermoelectric module, thermoelectric properties, waste heat recovery system.
4 Multifunctional Equipment for Low-temperature Separation of Food Solutions Based on The Effect of “Thermal Paradox”
Authors: Burdo O.G. 1, Terziev S. G.2, Mordynskiy V.P.1, Sirotyuk I.V.1, Fateeva Ya.A.1 1Odessa National Academy of Food Technologies, Odessa, Ukraine 2PRJSC “ENNI FOODS”, Odessa, Ukraine
  Abstract: The analysis of studies devoted to food solutions separation was carried out. The evolution of cryoconcentration technologies is analyzed, including the research works of the authors in the field of the block freezing plants. The purpose of the work is to reduce energy costs in block freezing plants and to intensify the process of the ice block formation. A hypothesis states that energy efficiency can be improved by recycling ice, using its energy to supercool the refrigerant before throttling. To intensify heat and mass transfer during crystallization, a scientific and tech-nical idea for the implementation of the "thermal paradox effect" is proposed. The essence of the effect is that, with a certain combination of design and operating parameters of a block freezer, the growth of an ice block leads to a decrease in the total thermal resistance in the circuit "refrigerant — block freezer's wall — ice block — solution". The most significant result of the work was that it proved the possibility to harmonize the design and operating parameters and organized the process of separation the solutions into ice and concentrate while minimizing sys-temic cold losses, and, and thus the ways were proposed for developing the freezing concentra-tion technique. The scientific significance of the obtained results lies in the fact that a new prin-ciple of efficient use of the ice block energy was proved in the work, and a new effect was ob-tained, which it was referred to by the authors as the "thermal paradox". The practical signifi-cance of the work was that a multifunctional freezing unit with ice recycling and frequency con-trol of the compressor drive was created.
  Keywords: heat and mass transfer, evaporation technologies, solution concentrating by freezing, seawater desalination, energy efficiency, modeling.
5 Algorithm for Selection Equipment to Reduce the Technogenic Effect on the Environment
Authors: Kozii I.S., Plyatsuk L.D., Koval V.V. Sumy State University Sumy, Ukraine
  Abstract: The work is devoted to the development of an algorithm for selection dust and gas purification equipment in order to reduce the anthropogenic impact on the environment from emissions of the heat, power and chemical industries, which are sources of complex environmental pollution. The need for the research was necessitated by the inefficiency of environmental measures taken due to the huge number of devices with different designs for emissions’ purification, their non-universality and low efficiency of the purification systems. The main goal of the study was to develop a software algorithm for the reasonable choice of the optimal dust and gas purification equipment, taking into account the actual conditions of the technological environment and the characteristics of pollutants. The goal was achieved using a logical and mathematical description of the pollutant parameters, environmental conditions and process equipment parameters. The uniqueness of the developed algorithm consisted of rechecking the compliance of each equip-ment parameter with environmental conditions and pollutant characteristics. The most important aims were to obtain an algorithm for selection efficient equipment, taking into account its pa-rameters and initial characteristics of pollutants and environmental conditions, the simplicity and accessibility of its implementation for a wide number of industrial facilities in the heat, power and chemical industries. The proposed algorithm, in contrast to the approaches used in practice, was characterized by the work flexibility due to the possibility of supplementing and improving the databases of pollutants and equipment.
  Keywords: technogenic load, dust and gas emissions, purification systems, selection algorithm, equipment, solution efficiency.
6 Monitoring of Energy Efficiency of District Heating System Facilities: Methodology for Determining the Energy Baseline
Authors: 1 Davydenko L.V., 1 Davydenko N.V., 1 Davydenko V.A., 2 Sprake D. 1 Lutsk National Technical University, Lutsk, Ukraine 2 Wrexham Glyndwr University, Mold Road, Wrexham, UK
  Abstract: Determining the energy consumption level is one of the stages of energy efficiency monitoring facilities. The aim of the article is to adapt the energy baseline to the operating conditions of the facility in accordance with the ISO 50000 Standards requirements. The methodology for deter-mining the energy baseline was proposed to achieve the goal. The three-stage procedure for forming a set of relevant variables of the energy baseline, which allows taking into account the significance of variables, the possibility of their measurement, controllability and control, and the procedure for constructing a multifactorial model of the optimal structure for determining the energy baseline are the main scientific results. This methodology was applied to a boiler house of a district heating system. Relevant variables were formed using a three-stage selection of fac-tors that influence the gas consumption efficiency of the boiler house. Combinatorial algorithm of the group method of data handling was used for gas consumption simulation. The search for models of optimal complexity was performed in six classes of basic functions. The selection of better structures of the mathematical model was realized based on the criteria for its appropriate-ness (regularity, unbiasedness criterion, Schwartz, determination coefficient) and accuracy of the forecast using the morphological criterion. As a result, a multifactor mathematical model of optimal structure was obtained. The percent forecasting error did not exceed 1%. The signifi-cance of the results lies in the fact that the proposed methodology can be applied to any facility.
  Keywords: relevant variables of the energy baseline, mathematical model of energy consumption, group method of data handling.
7 Experimental Investigation of Energy Consumption for the Process of Initial Heating of a Substrate to the Fermentation Temperature
Authors: Zablodskiy М.M.1, Spodoba M.O.1, Spodoba О.O.1 1National University of Life and Environmental Sciences of Ukraine, Kyiv, Ukraine
  Abstract: The aim of the work is to experimentally study the energy consumption for the process of initial heating of the substrate to the fermentation temperature in order to increase the energy efficien-cy of the biogas formation process. To achieve the goals set, a preparation and a series of exper-imental studies of the indicators of energy consumption for the process of initial heating of the substrate to the fermentation temperature were carried out. The working hypothesis is that the use of a heating cable built into the stirrer paddles reduces the energy costs for the process of initial heating of the substrate, increasing thus the energy efficiency of the biogas production. The most important result of the study was to obtain the dependences of the temperature change in the heating cable, substrate, reactor walls and energy consumption for heating and mixing dur-ing the initial heating of the substrate. The significance of the research results presented in the work lies in the fact that when using a heating cable built into the stirrer paddles, the process of initial heating of the substrate to the fermentation temperature occured faster on average by 16 minutes, and the amount of energy spent was also decreased on average by 6.6% for heating and 5.3% for mixing the substrate in a 40-liter biogas reactor. The implementation of the data obtained experimentally increased the energy efficiency of biogas production and the profitabil-ity of further processing of biogas into heat and electricity.
  Keywords: experimental study, initial heating of the substrate, energy consumption, energy efficiency, profitability, organic waste, digestion temperature.
8 Using soap waste from biodiesel production to intensify biogas generation during anaerobic digestion of cow dung
Authors: 1Polishchuk V.М., 1Shvorov S.А., 2Krusir G.V., 3Didur V.V., 4Witaszek К., 1Pasichnyk N.A., 1Dvornyk Ye.O., 1Davidenko T.S. 1 National University of Life and Environmental Sciences of Ukraine, Kyiv, Ukraine 2 Odessa National Academy of Food Technologies, Odessa, Ukraine 3 Uman National University of Horticulture, Uman, Ukraine 4 Poznań University of Life Sciences, Poznań, Poland
  Abstract: The aim of the work is to increase the yield of biogas and the generation of electricity at biogas plants due to the joint fermentation of cattle manure with the addition of soap stock obtained from soap waste from biodiesel production. To achieve this goal, the following tasks were solved: the yield of biogas from cattle manure was determined with the addition of soap stock for a periodic mode of loading the substrate, taking into account the data obtained, a mathematical model of biogas output for a quasi-continuous mode of loading the substrate into the digester was developed and its adequacy was confirmed. The novelty of the work lies in the fact that according to the data of experimental studies of biogas yield at a periodic loading mode using this model, it is possible to predict the maximum biogas yield for a quasi-continuous mode of loading the digester. The significance of the research results lies in the fact that when soap stock is added to the substrate with a periodic mode of loading the digester, a general increase in the biogas yield without diauxy is observed by about 2 times. The optimal content of soap stock in the substrate for a quasi-continuous mode of loading the digester, at which the biogas yield will be maximum, is 1.32%. When electricity is sold at a feed-in tariff, the payback period of a biogas plant is reduced from 8.7 years to 5.0 years.
  Keywords: biogas, substrate, cattle manure, soap stock, dry matter, digester, biogas plant, methane fermentation.
9 Method for Distinguishing the Digital Images in Different Formats
Authors: Kobozeva A.A., Bobok I.I., Kushnirenko N.I. Odessа Polytechnic National University Odesa, Ukraine
  Abstract: Nowadays, the energy systems are considered to be the main vital factor for the functioning of society. Today, this part of the infrastructure cannot exist without the informative infrastructure, so it needs efficient information and cyber protection. To detect the data integrity violations is one of the main tasks in the field of information security. In the paper the digital images are considered as information content. The image integrity violation often results in the change of the original storage format. The format change is an indicator of the image transformation. At the same time, this fact can be considered as an indirect indicator of its integrity violation. The effective method for distinguishing the original image in lossless format from the image re-saved to lossless format from lossy format is developed in the current work. The proposed method is an improvement of the method developed by the authors earlier. The method is based on the analysis of the number of non-intersecting image blocks, in which the normalized gap of maxi-mum singular value increases due to the image's re-saving into a lossy format. The algorithmic implementation of the improved method allowed us to reduce the examination time in 38-56 times for more than 50% of images originally stored in lossy format compared to the prototype method. The algorithm efficiency was evaluated using Type I and Type II errors, as well as ap-plying the accuracy coefficient (ACC). As a result of testing, Type I error was not detected, Type II error rate was 3.6%, ACC = 0.98. The obtained estimations are independent of the quali-ty factor used when the image was initially saved in a lossy format. The developed algorithm is more efficient than almost all modern analogues, except for the prototype one. The theoretical basis of the proposed improved method makes it possible to use it for the study of the digital image integrity, violated by a minor disturbance, in particular for steganalysis in conditions of low capacity of the hidden communication channel.
  Keywords: integrity violation, digital images, lossy format, lossless format, singular value.
10 Real-Time Decision-Making Systems: Approaches to Construction
Authors: Zakharchenko I., Dmitriev A., Ovcharenko V., Maslov I., Pavlenko M., Timochko A., Kryzhevska K. Kharkiv National Air Force University named after Ivan Kozhedub Kharkiv, Ukraine
  Abstract: The purpose of this work is the development of mathematical tools for formalizing decision-making problems in open expert real-time control systems. The goal was achieved by defining and formally describing all the elements of a formal system. The most significant result was the proposed approach to formalization. With its help, within the framework of a single formalism, the dynamic properties of the subject area and the logical-analytical activity of the power system dispatcher, presented in different classes of formal logics, were described. The significance of the results obtained lies in the possibility of a rigorous description of various aspects of knowledge within the framework of a single formal apparatus with further pragmatic interpretation in the management process. The proposed approach was distinguished by using the axioms of aletic and deontic logics and the development of axioms that reflect the specifics of the problems being solved. The introduced system of basic concepts and relations makes it possible to classify many decision-making problems for the power systems management. The goals were described within the framework of a single formalism form the basis of the apparatus for formalizing the decision-making problems of the class under consideration. The formalization apparatus provides a description of the dynamic properties of the system within each aspect of knowledge of the content paradigm. The direction of further research is the construction of an appropriate formal theory based on the proposed formal system.
  Keywords: control system, decision-making system, power system, real time, target setting, formal system.
11 Effective Implementation of Digital Technologies in the Field of Gas Supply
Authors: Beloglazova T. N., Romanova T. N. Perm National Research Polytechnic University Perm, Russian Federation
  Abstract: The work is devoted to improving the processes of digital technologies introduction in the field of the gas supply system on a methodological basis to enhance efficiency and reliability. The goal set in the study is to increase the reliability of the gas supply system of facilities based on the practical effectiveness of the digital technologies. This aim is achieved by solving the following tasks. Improving the methodology for assessing digital transformation in the field of gas supply. Application of the method of system analysis for the research, generalization of existing mathematical models and digital technologies. Identification of the modules of the main tasks for the implementation of an integrated method for improving the reliability of the gas supply system. The question of the criterion evaluation of the achievement of digitalization indicators is considered. So at the present stage, the digital technologies have already been introduced into the field of the gas supply, but the concepts of the basic level are not methodically defined. The most significant result is the improvement of the practical methodology for assessing digital transformation for the gas supply. A study of the current level of activity of gas distribution organizations shows a nonuniform level of the digital indicators for consumers and industrial facilities. The effectiveness of digital technologies is assessed taking into account the volume of gas consumption. The effect on economy, manufacturability and safety performance was made according to expert estimates and on the statistical data basis. The results of a multi-level modular-functional approach in estimation the digitalization of the effect were presented for the basic economically justified and promising level of the gas-supply digital transformation.
  Keywords: gas supply system, digital transformation, efficiency, digital model, management, safety, functional and technological criteria.
12 Integrated Method of Assessment the Type of Damages, their Localization and Predicting the Destruction of High-Voltage Electrical Equipment Insulators by the Partial Discharges Сharacteristics
Authors: Gataullin А.М., Gubaev D.F. Kazan State Power Engineering University Kazan, Russian Federation
  Abstract: The aim of this study is to improve the accuracy of localization of defects in insulators and determine their type. This goal is achieved by solving the problem of combining contact and remote methods for polymer and porcelain insulators using model partial discharges. The most significant results are the regularities of the dynamics of the characteristics of partial discharges up to the pre-breakdown situation for porcelain insulators, the study of the statistical distributions of partial discharges depending on their intensity, and the identification of the features of the statistical distribution of surface discharges. Part of the work is devoted to the study of the characteristics of partial discharges and their sources by spectra, polarity, statistical distributions, oscillograms, which is important from the point of view of automating the recognition of corona and internal partial discharges, as well as for the recognition of porcelain insulators destroyed by partial discharges. Regularities of changes in the statistical distribution of partial discharges up to the pre-breakdown situation were established. At the same time, the breakdown signs of the model discharge gap, the breakdown voltage values for defective and operable porcelain insulators are determined, which can be used to train models of artificial neural networks and recognize the pre-breakdown situation based on them. The most significant results were: assessment of the ohmic resistance of porcelain insulators by the characteristics of partial discharges, recognition of corona, internal and surface partial discharges of polymer insulators, localization of defects, using electromagnetic radiation sensors.
  Keywords: partial discharges method, diagnostics of high-voltage electrical equipment insulators, localization of high-voltage insulators defects, state of high-voltage electrical equipment monitoring.
13 Congratulations to M.S. Tirsu on his jubilee
Authors: The staff of the Institute of Power Engineering
  Abstract: The staff of the Institute of Power Engineering the editorial board of the journal "Problems of Regional Energetics" congratulates with a glorious jubilee the Doctor of Technical Sciences, Mikhail Stepanovich Tirsu, Director of the Institute of Energy, editor-in-chief of the journal with a glorious Jubilee of 50 years since his birth! On this remarkable day we wish your Health, Happiness, Great Success, further success in your professional scientific activity for the benefit and prosperity of the Republic of Moldova, fruitful work, successful implementation of the most daring plans and projects, good health, many years of active life, full of successes, and great personal happiness!
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