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Документ Відкритий доступ 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.Документ Відкритий доступ 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.