Browsing by Author "Kovzel, Maksim"

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    Development of a Method of Calculating the Temperature of a Survey Assembly When Preparing a Train Dispatch
    (Львовский политехнический национальный университет, Львів, 2020) Ustymenko, Dmytro V.; Kuznetsov, Vitaliy; Marenych, Oksana L.; Kovzel, Maksim; Mukha, Andrii M.; Sinkevych, Oleksiy; Tryputen, Mykola; Al Said Ahmad, Mohammad Ahmad Diab
    ENG: The features of the thermal state of the current collection unit «contact wire – contact insert of the current collector» in the conditions of preparation of electric rolling stock for the journey are considered. As part of the study, a methodology has been developed for estimating the heating temperature of the power sliding contact zone in the conditions of train preparation for journey. Application of the method will help to reduce the number of «burnouts» of the contact wire due to the exact selection of the heating/cooling time of the train for a certain heating/conditioning current when preparing the electric rolling stock for the journey. It was established that the cause of the «burns» of the contact wire in the parking lots when preparing the train dispatch is the excess of the permissible temperature of the power sliding contact as a result of the prolonged action of the heating/conditioning current. The standard approach for determining the duration of heating is based on the average values of the loads on the system and therefore does not take into account some factors, for example, the state of the contact wire, the state of the contact insert of the current collector, the number of cars in the train, and so on. The proposed technique is based on the classical theory of electrical contact and the theory of heating a homogeneous body, which makes it possible to accurately assess the thermal state of the power sliding contact and convenient enough for use in operating conditions. The results of the work are of practical value, since the technology of preparing a train for dispatch can be supplemented by calculating the contact temperature «contact wire element – contact insert element» in accordance with the proposed methodology. This will allow for a specific train in specific conditions to apply a set of measures to prevent «burnout» of the contact wire in the event of a possible temperature exceeding the permissible value.
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    Development of Mathematical Models of Energy Conversion Processes in an Induction Motor Supplied from an Autonomous Induction Generator with Parametric non-Symmetry
    (НВП ПП «Технологічний Центр», Харьків, 2021) Chenchevoi, Volodymyr; Kuznetsov, Valeriy; Kuznetsov, Vitalii V.; Zachepa, Iurii; Chencheva, Olga; Chornyi, Oleksii; Kovzel, Maksim; Kovalenko, Viktor; Babyak, Mykola O.; Levchenko, Serhii
    ENG: The paper presents studies of the system “induction generator-induction motor” with parametric asymmetry on a mathematical model to determine the quality of generated electricity in load operating modes. A mathematical model of the “induction generator-induction motor” system has been developed taking into account losses in steel and parametric asymmetry. The analysis of the transient characteristics of an induction generator when a motor load is connected in symmetrical and asymmetrical modes of operation is carried out. The results of changes in the main characteristics of an induction motor at various degrees of parametric asymmetry in the generator are presented. The quality of the generated electricity was analyzed based on the calculations of the unbalance coefficients for each of the operating modes. The assessment of the thermal state in steady-state conditions was carried out using an equivalent thermal equivalent circuit. Thermal transients were investigated when starting an induction motor from an autonomous energy source based on an induction generator. On a thermal mathematical model, the study of the effect of the output voltage asymmetry on the heating of the connected induction motor was carried out. It is shown that the asymmetry of the output voltage of an induction generator reaches 3–10 % and causes overheating of the windings in excess of the permissible values. A regression model has been developed for studying the operating conditions of an induction motor when powered by an induction generator with an asymmetry of the stator windings. The use of the obtained equations will make it possible to determine the most rational combination of factors affecting the heating of the stator windings of induction machines, in which they will not overheat above the maximum permissible temperature values of the corresponding insulation classes.