Перегляд за Автор "Trotsenko, Y. O."

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    Modeling and analyzing the effect of connection to the network of a harmonic source having various total harmonic distortion factors on load signal waveforms
    (КПІ ім. Ігоря Сікорського, 2022) Peretyatko, J. V.; Trotsenko, Y. O.; Polishchuk, N. O.
    This article examines the effect of a network connected source of harmonics having a total harmonic distortion factor varying from 5% to 15% on load voltage and current waveforms. When a source of higher harmonics is connected to the network, both in the network and in the load, the effective values of voltage and current increase, that can negatively affect the cable line insulation, accelerating its destruction and aging. To analyze the consequences of a power quality deterioration, a 20 kV network was simulated, consisting of a 20 kV symmetrical generator, an XRUHAKXS-20(1x120/50) power cable line 20 km long, a step-down transformer 20/0.4 kV with a power of 2 MVA, with windings connected in delta-star, and a three-phase symmetrical load. The values of the currents flowing through the cable conductor, obtained as the result of simulation were used to calculate the voltage drop between the cable conductor and its shield. Results obtained show that the connection of a harmonic distortion source to a network leads to a magnification of a current flowing through the cable conductor by more than 2%. The model proposed in the article can be used further for a more detailed study of solar photovoltaic plants connection to the grid. One of the biggest problems regarding solar power plants is that its electricity generation is intermittent. Thus, future efforts should be focused on modeling and studying the higher harmonics generation during switching on and off of the solar photovoltaic plants.
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    Overview of factors affecting the estimation of lightning shielding performance of overhead transmission lines
    (КПІ ім. Ігоря Сікорського, 2022) Trotsenko, Y. O.; Peretyatko, J. V.; Dixit, M. M.; Hohol, V. V.
    This paper examines the risk of lightning stroke to overhead transmission line. The estimation procedure for the lightning performance of overhead power lines is based on the selected lightning attachment model, available lightning parameter statistics, the transmission tower design and voltage levels, type of overvoltage and other characteristics. In this paper the overview of factors affecting the estimation of lightning shielding performance of overhead transmission lines was performed. Among the factors that can affect the estimation accuracy, one can list insufficiently accurate data on the ground flash density in the area of interest and lack of complete data on statistical distribution of lightning current magnitudes. The paper shows that the influence of wind on the increase in the horizontal exposed distance of the phase conductor is not also taken into account. In this research traditional electro-geometric model was used for estimation of lightning performance of 220 kV overhead power line. Results obtained suggest that swing of suspension insulator strings caused by strong winds may lead to increased risk of lightning shielding failure during thunderstorm. Calculation performed for 3 kA lightning current magnitude shows that at swing angle equal to –1 degree, the horizontal unprotected distance of phase conductor increases by 3.1%, that corresponds to 5.240 m uncovered width. When the swing angle is increased to –5 degree, the uncovered width is increased by 15.8% that corresponds to 5.885 m uncovered width. It is proposed that an increase in the risk of lightning shielding failure as a result of wind load can be accounted by applying an appropriate correction factor in expressions for calculation of shielding failure rate, shielding failure flashover rate, etc. Proposed correction factor should account frequency and strength of wind in the area of transmission line route and depend on transmission line voltage level and tower design. Further efforts should be focused on obtaining and justifying the numerical values of this correction factor.
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    Study of physical processes in laminated magnetic cores of electric machines
    (КПІ ім. Ігоря Сікорського, 2021) Chumak, V. V.; Kovalenko, М. А.; Trotsenko, Y. O.; Ihnatiuk, Y. S.; Stulishenko, A. S.
    The aim of the work is to use fast-moving processes to detect defects in the interlayer insulation of laminated magnetic cores of electric machines. Damages of interlayer insulation causes increased eddy currents as a result of increased losses and integral local overheating in the magnetic core. The article develops a mathematical field model of induction distribution in a toroidal toothed magnetic core of a 0.37 kW 4AA63V4U3 asynchronous motor when superimposed on the back of the core of the power winding powered by a high frequency voltage source in the given range. An experimental study of losses in the magnetic core and the distribution of eddy current losses and magnetization reversal (hysteresis) were carried out. When designing an electric machine, its performance, optimum operating conditions, thermal state and many other factors are calculated using the nominal values of the parameters of steel, windings and all materials used in the machine. However, these materials do not always have the declared characteristics and quality. For example, in the manufacture and stamping of electrical steel sheets, it experiences a significant level of influence, which in a certain way affects its characteristics. In addition, even if one assume that during production all the stages of manufacturing the material came flawlessly, the state and, as a result, the parameters of the materials and the electric machine as a whole change during operation as a result of emergencies or even simple aging and wear. Therefore, given these facts, it becomes clear that during planned or unplanned repairs it makes sense to check the condition of materials, insulation, since the allowable loads, temperature conditions, etc. depend on their condition. In particular, the state of the magnetic core largely determines the temperature around the conductors in the grooves and, as a result, determines how long the winding will actually last, in contrast to the specified service life and the rated power at which this electric machine should be used. The concept of the state of the magnetic core can be divided into the state of electrical steel and the state of its insulation. The first component changes rather little during operation and is generally caused by the "aging" of the steel, except for any serious damage as a result of faults, but it can be damaged during manufacture. But it is the second component that is significantly influenced during operation and significantly determines the quality of the magnetic core as a whole.