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  Problemele energeticii regionale

E-Journal N3(55) 2022



1 Thermal Model of the Output Traction Converter of an Electric Locomotive with Induction Motors
Authors: Goolak S.1, Kyrychenko M.2 1State University of Infrastructure and Technologies Kyiv, Ukraine 2Kyiv National University of Construction and Architecture Kyiv, Ukraine
  Abstract: The aim of research is to develop a thermal model of the output converter of an electric locomotive with vector control, taking into account the operating modes of the electric locomotive. The aim was achieved by using energy losses at the moments of switching functions that describe the nature of the change in the curves of currents and power voltages of transistors and converter diodes. The object of research is an autonomous voltage converter, which is part of the traction drive of an electric locomotive with a vector control system. The simulation was carried out for an autonomous voltage converter, the load of which is two traction induction motors operating in the nominal mode. The temperature of transistors and diodes is obtained for the established modes of operation of traction motors. The most important results are the analytical dependence of thermal power losses in the inverter as a function of inverter phase currents and voltages. The significance of the results obtained is to establish the dependence of the temperature of the power devices of the inverter on the actual operating conditions of the electric locomotive. The established dependencies will further determine the spectral power of thermal noise. This will allow, when designing a traction drive control system, to develop an effective system for filtering thermal noise. This will increase the energy performance of the traction drive of the electric locomotive by improving the accuracy of regulation.
  Keywords: heat loss energy, diagnostics, induction motor, mathematical modeling, autonomous voltage inverter, temperature, thermal resistance.
2 Analysis and Simulation of Overmodulation Modes of a Three-Inverter Block of the Photovoltaic Installation
Authors: Oleschuk V. Institute of Power Engineering of Moldova Kishinau, Republic of Moldova
  Abstract: The purpose of this work is to modernize the control scheme of a transformer-based photovoltaic system with three inverters controlled by the modified algorithms of synchronous space-vector PWM in order to ensure linear regulation of the system in the overmodulation zone of the inverter block in the process of forming a symmetrical and synchronized (with the operating frequency of the system) voltage on the inverter-side windings of a power transformer. This goal is achieved by the fact that the process of two-stage control of the system in the zone of overmodulation of inverters is carried out on the basis of synchronized phase shifts between the control signals of inverters (a constant phase shift, as well as an additional adjustable phase shift between the inverter signals as a function of the duration of clock subintervals), with an appropriate modification of the algorithms of synchronous PWM of inverters due to the inclusion of two specialized correction factors in the basic functional dependencies. The most significant results of the work include the fact that in a system with a modified control scheme and modulation of the inverter block in the overmodulation zone, the resulting voltage on the inverter-side windings of the power transformer is characterized by quarter-wave symmetry, and its spectrum contains no even-order harmonics, as well as subharmonics, including regimes of fluctuations in the operating frequency of the system connected to a three-phase network, thereby helping to reduce losses in the transformer windings and improve the efficiency of photovoltaic systems.
  Keywords: voltage source inverter, photovoltaic system, multi-winding transformer, synchronous pulse modulation, spectrum of the voltage waveform.
3 Identification of Internal Electromagnetic Defects of Implicit-Pole Synchronous Generators Based on the Information of its External Magnetic Field
Authors: Morozov A.N., Kazakov Ju.B., Morozov N.A., Nesterov S.A. Ivanovo State Power Engineering University, Ivanovo, Russian Federation
  Abstract: The objectives of the work are to develop a non-contact method of detecting internal electro-magnetic defects in synchronous generators based on the analysis of asymmetry of the external magnetic field distribution resulting from damage, establishing the relationship of defects of a generator with the pattern of field distribution, identifying diagnostic signs for the defects. These objectives are achieved by developing and using three-dimensional finite-element models of the external magnetic field of synchronous generators, by studying and analyzing the results of nu-merical simulation of external magnetic fields, by comparing the simulation results with experi-mental data. Significant results of the work include the improvement of the non-contact method for detecting internal electromagnetic defects in synchronous generators, revealing how defects of the generator manifest themselves in the asymmetry of magnetic field distribution, and detect-ing the correlation of field asymmetry with the type and severity of defects. For implicit-pole synchronous generators, it is reasonable to use the field asymmetry coefficient determined by the shift in the magnetic field distribution caused by field coils damage. The sign of the coeffi-cient indicates the pole with a damaged field coil. The value of the coefficient characterizes the severity of damage to the field coils, with a critical value of 0.1. The significance of the results lies in the possibility of timely and non-contact diagnostics of internal electromagnetic defects of implicit-pole synchronous generators, which can significantly reduce the economic damage from failures of generators without installation of diagnostic sensors of damage inside the generators.
  Keywords: synchronous generators, electromagnetic defects, external magnetic field, numerical simulation, asymmetry of magnetic field distributions, defect diagnosis, non-contact method.
4 The Coal Dust Combustion Scheme for an Invert Furnace of an A-USC M-Shaped Boiler
Authors: Prokhorov V.B., Kirichkov V.S., Chernov S.L., Fomenko N.E. Moscow Power Engineering Institute (MPEI, National Research University) Moscow, Russian Federation
  Abstract: The M-shaped boiler construction for the advanced ultrasupercritical steam parameters (A-USC) is proposed in this work. The boiler was designed to operate in a 500 MW unit on low volatile hard coal. This design allows reducing the pipelines length of the high cost steam pipelines made of nickel alloys. A downstream (invert) furnace is offered for this boiler type. The coal dust burning scheme design using the direct-flow burners and nozzles in a system of vertical and horizontal tangential torches and the solid ash removal are proposed. This approach was extensively used earlier on standard shaped boilers, and it was upgraded now for an invert furnace. The goals are achieved by conducting research on the physical furnace model and thermal furnace processes numerical simulation by computational fluid dynamics software. The most significant research results were as follows: the oxidizer stage supply was performed along the torch length and furnace height; the dynamic jet pressure on the furnace walls was excluded; a high degree of coal burnout was ensured due to the vortex furnace aerodynamics implementation; the uniform furnace section filling with air jets was performed; turbulent jets ejection was significantly higher than that for a flat submerged jet; chemical underburning loss did not exceed 0.1%; and unburned carbon loss was 0.8%. The carbon monoxide concentration at the furnace outlet in terms of air excess ratio equal to α=1.4 was 226 mg/nm3. The nitrogen oxides concentration in the flue gases (normalized) was 424 mg/nm3. The results significance obtained during the research is efficient solid fuel use with high technical and economic boiler performance.
  Keywords: steam boilers, coal fuel, vortex flame, staged combustion, nitrogen oxides, ultra-supercritical steam parameters, fuel combustion efficiency.
5 Analysis of the combustion characteristics of hydrogen and hydrocarbon fuels based on the results of numerical simulation
Authors: Matyunin O.O., Arkhipov S.K., Shilova A.A., Bachev N.L., Bulbovich R.V. Perm National Research Polytechnic University Perm, Russian Federation
  Abstract: At present, an upward trend in the field of studying the processes of hydrogen combustion in the combustion chambers of the ground-based gas turbine power plants is obvious. The use of pure hydrogen as a fuel gas would solve the problem of environmental decarbonization. One of the emerging problems is to ensure the stable combustion of such fuels in combustion chambers of various applications. The information-analytical review of studies showed that there is a large number of theoretical and experimental results on the diffusion and homogeneous combustion of hydrogen and hydrogen-containing fuels in various burners and combustion chambers, which are not part of the existing gas turbine power plants. The purpose of this work is a comparative analysis of the gas-dynamic and emission characteristics of the combustion of the hydrogen-air and methane-air components based on the results of numerical simulation of a convertible com-bustion chamber of a 75 kW microgas turbine power plant. This goal is achieved by numerical simulation of the diffusion combustion of hydrogen and methane with air in a convertible com-bustion chamber. The most significant result of the work is obtaining the isosurface of the flame, which made it possible to obtain the conditions for stable combustion in the form of the Damköhler criterion and the ratio of the midsection velocity to the velocity of turbulent combus-tion. The significance of the results obtained lies in the further development of the methodology for the conversion of megawatt-class gas turbine plants to hydrogen and hydrogen-containing fuels.
  Keywords: hydrogen energy, numerical simulation, conversion of gas turbine plants, stable position of the flame, combustion characteristics, recommendations for the use of hydrogen.
6 Efficiency of CHPP Operation in Heat-Supply Systems when the Transition to Lowered and Extended Schedules of Heating Regulation
Authors: Suvorov D.M., Tatarinova N.V. Vyatka State University Kirov, Russian Federation
  Abstract: The aim of the work is a theoretical study of the efficiency of heat supply based on a software package that includes mathematical models of a real CHPP, a real heating network and real heat consumers with a high share of hot water supply load using extended and reduced temperature schedules of heating regulation. The set aim is achieved by solving the following problems: choosing a method for calculating various schedules of regulating heat supply from CHPPs; con-struction of initial, reduced and extended temperature schedules and schedules of delivery water consumption; determination of optimal energy costs and heat-transfer agent costs. The most im-portant of the results achieved is the carried analysis of the energy and economic efficiency in-dicators changes during the transition from the traditional to lowered and extended schedules of heat-supply system regulation. The total fuel savings at CHPP during the transition from the ini-tial design temperature schedule with a maximum delivery water temperature of 150°C to the most energy efficient schedules reaches about 2%, which should be recognized as very signifi-cant. The significance of the obtained results lies in the fact that they allow calculating the ener-gy effect in the form of fuel savings at CHPPs compared to their operation with the design tem-perature schedule. It is shown that the use of these technologies will increase the efficiency of district heating that will ensure a reliable and high-quality supply of heat energy to consumers and reduce its cost.
  Keywords: heat-supply system, heating load, heating regulation, temperature schedule, CHPP, specific reference fuel consumption, delivery water.
7 Determination of the Optimal Algorithm for the Operation of a Hybrid Power System with a Regulating Generator
Authors: Kuznetsov N. Institute of Renewable Energy, National Academy of Sciences of Ukraine National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute” Kyiv,Ukraine Lysenko O. Dmytro Motornyi Tavria State Agrotechnological University Melitopol, Ukraine
  Abstract: The purpose of the article is to study the possibilities of preventing the imbalance caused by the stochastic nature of RES by regulating the electricity accumulation and the backup generator. The subject of the research is random processes of energy generation and consumption. The goal is achieved by a mathematical model construction in which the system parameters would be formalized and allow the choice of optimal options. The mathematical model uses random functions to obtain statistical estimates, and is implemented as sequential models of energy generation and consumption as an integrated random process. The models’ adequacy is confirmed by comparing the simulated and real indicators for a number of existing RES in Ukraine. The proposed approach made it possible to establish the presence of system parameters that minimize energy losses and consumption, reduce the probability of energy imbalance, and effectively use the reserve power. The proposed mathematical model allows determining the probability of various system states, it estimates the reliability of energy supply, and minimizes losses at the stages of designing a power system and planning its operating modes. The above estimates are typical for certain climatic conditions and modes of energy consumption, and are of a specific nature. The significance of the work lies in the fact that the proposed formulation of the problem makes it possible to adapt the mathematical model to various conditions, to find implicit dependencies between the technical parameters of the system and its indicators in order to find optimal solutions.
  Keywords: local energy system, renewable energy sources, battery, generator, power balance.
8 Monthly Runoff Forecasting by Non-Generalizing Machine Learning Model and Feature Space Transformation (Vakhsh River Case Study)
Authors: Matrenin P.V.1, Safaraliev M.K.2, Kiryanova N.G.1, Sultonov S.M.3 1Novosibirsk State Technical University, Novosibirsk, Russian Federation 2Ural Federal University, Yekaterinburg, Russian Federation 3Tajik Technical University, Dushanbe, Tajikistan
  Abstract: Energy prices and сost of materials for solar and wind power plants have increased over the past year. Therefore, significance increases for the hydropower and long-term (1–10 years) planning generation for the existing hydropower plants, which requires forecasting the average monthly values of the river flow. This task is especially urgent for countries without their own oil-fields and opportunity to invest in the creation of solar or wind power plants. The aim of the research is to decrease the mean absolute forecasting error of the long-term prediction for the Vakhsh River flow (Tajikistan) based on the long-term observations. A study of existing methods for the river runoff forecasting in relation to the object under consideration was carried out, and a new transformation model for the space of the input features was developed. The most significant results are the decrease in the average forecast error in the Vakhsh river flow achieved by the use of the proposed space of polynomial logarithmic features in comparison with other methods, and the need to use at least the 20 year-old observational data for the long-term operation plan-ning of the hydropower plants and cascades of the hydropower plants obtained from the results of computational experiments. The significance of the results lies in the fact that a new approach to the long-term forecasting of river flow has been proposed and verified using the long-term observations. This approach does not require the use of the long-term meteorological forecasts, which are not possible to obtain with high accuracy for all regions.
  Keywords: river flow, hydropower, long-term forecasting, generation planning, machine learning, Republic of Tajikistan, cascade of hydropower plants.
9 Energetics and Kinetics of Plant Raw Material Dehydration Processes
Authors: Burdo O.G.1, Terziev S.G.2, Burdo A.K.1, Sirotyuk I.V.1, Pylypenko E.A.1, Akimov A.V.1, Molchanov M.Yu.1 1Odessa National University of Technology, Odesa, Ukraine 2PRJSC “ENNI FOODS”, Odesa, Ukraine
  Abstract: The aim of this work is the energy-efficient equipment creation for production of a high-quality dry product from a plant raw material and development of scientific and engineering foundation for the design of such an equipment. The achievement of this aim lies in a deep analysis of ten-dency in the development of a drying theory and technique. The graph is presented, on the basis of which the development of heat and moisture transfer model of A.V. Lykov is given, taking into account the P. A. Rebinder moisture bond forms specificity. The problems of convective drying modern technologies are determined; the reasons of high-energy consumption during their work are substantiated. The electrodynamic dehydrators classification is given, which con-sideres the combined simple modes (drying) and hybrid dehydration modes. On the basis of the first law of thermodynamics, the possibility of a significant decrease in energy consumption is shown by the organization of a “vapordynamic” effect. The most significant result of the work is the construction of the electrodynamic apparatus module for dehydration of food and medici-nal plant raw material. By the combination of electromagnetic field with the filtration process the specific energy consumptions were 1.9 MJ per 1 kg of the removed moisture, at the hybrid pro-cesses — juice yield exceeded vapor yield by 3.5 times. The significance of the work consists in the fact that the scientific conception of the authors on the possibilities of the significant de-crease in energy consumption during the raw material dehydration at the innovative electrody-namic type apparatuses was practically proven.
  Keywords: electrodymanic apparatuses, energy technologies, drying, dehydration, mathematical and experimental modeling, food and medicinal plant raw material.
10 Increasing the Efficiency of the Drying Process of Fruits Treated Using SHF Method
Authors: 1Popescu V., 2Tirsu M., 3Tsislinscaia N., 3Vishanu V., 3Balan M., 3Melenchuk M. 1State Agrarian University of Moldova, Kishinau, Republic of Moldova 2Institute of Power Engineering of Moldova, Kishinau, Republic of Moldova 3Technical University of Moldova, Kishinau, Republic of Moldova
  Abstract: The aim of this work is to increase the efficiency of the fruit drying process with the SHF treatment in a uniform rectilinear movement. In order to achieve the purpose of the work, an experimental installation for fruit drying was developed with the application of the SHF treatment in the uniform rectilinear movement, on the basis of which the research was carried out. The efficiency of the drying process with the application of the experimental installation was estimated for 3 types of fruits: peaches, pears and apples. These types of fruit have been selected for the study because their drying is currently problematic, and they are of great interest to consumers and to processing and marketing businesses. The main results obtained regarding the application of the plant developed for fruit drying are: the drying process speed increase, the heat processing time decrease, the electricity consumption reduction, the dried fruit quality improvement and the processing costs reduction. Moreover, the installation is simple in terms of construction, low cost and easy use. At the same time, the installation allows the automation of the process, and during the research it demonstrated a high level of safety. The significance of the results obtained lies in solving a number of current problems faced by primary agri-food processing companies, by streamlining the process of drying fruit in rounds, mainly by reducing the technological processing costs and improving the quality of dried fruit for storage, marketing and use in nutrition.
  Keywords: fruit drying, process efficiency, uniform rectilinear movement treatment, drying plant.
11 Investigation of Powerful Electromagnetic Radiation Influence on Receiving Antenna Systems with Superconducting Protective Device
Authors: Yeromina N.S.1, Kravchenko I.I. 2, Kurylov M.N. 3, Borysenko V.P. 1, Borysenko T.I. 1, Kyvliuk V.S.4, Kryvosheiev V.V.4, Pribyliev Y.B. 4, Gnusov Y.V. 5, Radchenko V.V. 5, Kaliakin S.V. 5 1 Kharkiv National University of Radio Electronics, Kharkiv, Ukraine 2 Ivan Kozhedub Kharkiv National Air Force University, Kharkiv, Ukraine 3 National Academy of the National Guard of Ukraine, Kharkiv, Ukraine 4National Defense University of Ukraine named after Ivan Cherniakhovskyi, Kiev, Ukraine 5 Kharkiv National University of Internal Affairs, Kharkiv, Ukraine
  Abstract: This work is devoted to the problem of the effect of a powerful ultra-short duration electromagnetic radiation on the superconducting protection device as a load of antenna-feeder circuit of radioelectronic systems. The above device is used in the monitoring systems of the land surface to the benefit of agriculture, geodesy, mapping, monitoring of land and ocean surfaces, and, also, the atmospheric layers, remote control systems in engineering and industry related branches. This goal was achieved by substantiation of the approach to the description of the arbitrary antenna response to the electromagnetic radiation, using the antenna system frequency response. The most significant result is the offered approach to the relationship determination between the response of the arbitrary antenna to the radiation influence and its characteristics in a radiation mode. The sought relationship determination showed that, such characteristics of the antenna systems are the antenna input impedance and the complex normalized radiation pattern in the radiation mode at an arbitrary frequency. The significance of the results is in obtainment of the analytical relations to estimate the effect of the radiation under consideration on the device that is in superconducting, mixed and normal phase states. The peculiarity of the obtained results makes it possible to consider the antenna system coordination degree of the protection device based on superconducting thin film. Conversion of the radiation energy into the induced currents’ energy that is the basis for selection and structural calculation of protection devices of the radio electronic facilities against powerful electromagnetic radiation build upon microstrip transmission lines.
  Keywords: radio-electronic means, powerful electromagnetic radiation, protection device, antenna system, superconducting thin film, phase states.
12 Using the Mathematical Apparatus of Cellular Automata to Solve the Problem of Monitoring Critical Infrastructure Objects by Unmanned Aerial Vehicles
Authors: Chistov V., Zakharchenko I., Pavlenko V., Pavlenko M., Berdnik P., Timochko A., Kryzhevskaya 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.
13 V.I. Oleschuk - 75 years! Congatulations!!!
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