Розвиток методів контролю технічного стану електричної ізоляції за параметрами ємності та тангенса кута діелектричних втрат
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Дата
2023
Автори
ORCID
DOI
Науковий ступінь
доктор технічних наук
Рівень дисертації
докторська дисертація
Шифр та назва спеціальності
05.11.13 – прилади і методи контролю та визначення складу речовин
Рада захисту
Спеціалізована вчена рада Д 64.050.09
Установа захисту
Національний технічний університет "Харківський політехнічний інститут"
Науковий керівник
Члени комітету
Мигущенко Руслан Павлович
Сучков Григорій Михайлович
Кіпенський Андрій Володимирович
Сучков Григорій Михайлович
Кіпенський Андрій Володимирович
Видавець
Національний технічний університет "Харківський політехнічний інститут"
Анотація
Дисертація на здобуття наукового ступеня доктора технічних наук за спеціальністю 05.11.13 – прилади і методи контролю та визначення складу речовин. – Національний технічний університет «Харківський політехнічний інститут», Харків, 2023 р. Дисертацію присвячено розвитку методів контролю технічного стану електричної ізоляції електроенергетичного та телекомунікаційного обладнання за параметрами її електричної ємності та тангенса кута діелектричних втрат за рахунок зменшення впливу паразитних індуктивних та ємнісних параметрів досліджуваних об’єктів контролю на результати вимірювання а також вдосконалення алгоритмів обробки кривих струму та напруги і числових рядів результатів вимірювань. В дисертації розроблено модифікацію кореляційного методу вимірювання фазового зсуву, що дозволило збільшити завадостійкість розрахунку тангенса кута діелектричних втрат в діапазоні значень від 0º до 45º. Розроблено метод вимірювання електричної ємності та тангенса кута діелектричних втрат трьох-жильних силових кабелів з паперовою імпрегнованою ізоляцією. Розроблений метод передбачає резистивно-ємнісне заземлення досліджуваного фазного шару ізоляції із наступним вимірюванням напруги на досліджуваному шарі ізоляції та між однією із жил кабелю та його заземленою оболонкою для формування системи рівнянь, вирішення якої дозволяє визначити невідомі значення ємності та тангенса кута діелектричних втрат. Також в дисертації проаналізовано специфічні особливості часових рядів та амплітудних спектрів результатів вимірювання електричної ємності та тангенса кута діелектричних втрат екранованих та неекранованих телекомунікаційних кабелів на основі витих пар, наведено схемотехнічні рішення по побудові елементів вимірювачів електричної ємності, побудованих на застосуванні перетворювачів напруги в струм, розроблено метод вимірювання паразитної індуктивності ємнісних об’єктів контролю для їх аперіодичного режиму розряду.
Thesis for obtaining the scientific degree of Doctor of Technical Sciences in the field – 05.11.13 - devices and methods of control and determination of the composition of substances. National Technical University "Kharkiv Polytechnic Institute", Kharkiv, 2023. The dissertation work is devoted to the solution of the problem of development of methods of monitoring the technical condition of electrical insulation according to the parameters of its electrical capacity and tangent of the dielectric loss angle. In the first chapter of the dissertation, based on a critical analysis of physical models of aging of electrical insulation under the influence of adverse operating factors, the most common methods of controlling the insulation of power cables by applying high voltage pulses, measuring the level of partial discharges, absorption methods of control, measuring its electrical capacity and the tangent of the angle of dielectric losses, as well as methods of the theory of digital signal processing, which are used both in the analysis of numerical series of the obtained measurement results and directly in the systems for measuring the capacitance and tangent of the dielectric loss angle, the main tasks of the dissertation research are formulated. In the second chapter, using the example of the analysis of the numerical series of the results of the measurement of the electric capacity and the tangent of the dielectric loss angle, it is shown that the physical interpretation of the results obtained by analyzing the C-tgδ diagrams can be complicated due to the simultaneous growth of these parameters, which contradicts the functional dependence between these parameters for the case of electrical insulation application of a parallel scheme for replacing the investigated capacitive object of control with dielectric losses. Taking into account the mentioned difficulties, in order to identify the presence of hidden oscillations in the obtained results, it is proposed to carry out a spectral analysis of numerical series. Using the example of harmonic signals, a method of interval estimation of the frequency of such hidden oscillations has been developed, which allows to reduce the influence of the spread of the spectrum of signals on the accuracy of estimation of their parameters. A spectral analysis of numerical series of the results of measuring the tangent of the dielectric loss angle was carried out and it was shown that the application of the proposed selection of frequencies of auxiliary trigonometric functions by which the investigated signal is decomposed allows to double the resolution of the Fourier transform without the traditional addition of zeros to the investigated numerical sequence and to halve the number of necessary calculations. by refusing to decompose the investigated signal using a complete system of orthogonal trigonometric functions. In the third section, a modification of the correlation method for measuring the phase shift was developed in order to improve the interference resistance of measurements of the tangent of the dielectric loss angle for control objects with a relatively low Q level. The developed modification requires calculations of several scalar products of the studied current and voltage signals with auxiliary trigonometric functions. The results of the comparative analysis of immunity showed that, compared to the traditional correlation method of measuring the phase shift, the developed modification made it possible to increase the immunity of the measurement of the phase shift between the current and voltage curves and, accordingly, the tangent of the dielectric loss angle in the range of values from 0º to 45º. At the same time, in the range from 45º to 90º, the classic correlation method of measuring the phase shift has a higher level of immunity compared to its developed modification. The fourth chapter analyzes the peculiarities of measuring the individual parameters of the dielectrics of each layer of insulation in three-core power cables with paper-impregnated insulation. The possibility of the existence of correlations between the results of measurements of the aggregate values of the electric capacity, which were obtained when using different methods of connecting the conductive elements of the power cable structure, is shown. The component variances of the results of the measurement of the partial insulation capacities of three-core power cables were analyzed and the formulas for the direct calculation of the values of the tangent of the dielectric loss angle using aggregate measurements were obtained. In the fifth chapter, based on the modified connection schemes of the conductive elements of the construction of the threewire power cable in a common metal sheath, a method of measuring the electrical capacity and tgδ of each of its insulation layers is developed. The developed modification of the existing inspection schemes provides for resistive or resistive-capacitive grounding of the tested insulation layer. Determination of unknown insulation parameters is carried out by adjusting the value of the electrical resistance through which the investigated insulation layers are grounded, until the moment of zero phase shift between the voltage on the investigated insulation layer and on its grounding elements, followed by the measurement of these voltages. In the sixth chapter, a theoretical analysis of the effect of the parasitic inductance of the investigated capacitive control object on the results of measuring the electric capacity and the tangent of the dielectric loss angle for the measurement circuit based on a voltage-to-current converter and a phase detector is carried out, solutions are given for the development of circuits for shifting the phase of harmonic signals by 90º , developed a methodology for estimating the parasitic inductance of capacitive control objects for their aperiodic discharge mode.
Thesis for obtaining the scientific degree of Doctor of Technical Sciences in the field – 05.11.13 - devices and methods of control and determination of the composition of substances. National Technical University "Kharkiv Polytechnic Institute", Kharkiv, 2023. The dissertation work is devoted to the solution of the problem of development of methods of monitoring the technical condition of electrical insulation according to the parameters of its electrical capacity and tangent of the dielectric loss angle. In the first chapter of the dissertation, based on a critical analysis of physical models of aging of electrical insulation under the influence of adverse operating factors, the most common methods of controlling the insulation of power cables by applying high voltage pulses, measuring the level of partial discharges, absorption methods of control, measuring its electrical capacity and the tangent of the angle of dielectric losses, as well as methods of the theory of digital signal processing, which are used both in the analysis of numerical series of the obtained measurement results and directly in the systems for measuring the capacitance and tangent of the dielectric loss angle, the main tasks of the dissertation research are formulated. In the second chapter, using the example of the analysis of the numerical series of the results of the measurement of the electric capacity and the tangent of the dielectric loss angle, it is shown that the physical interpretation of the results obtained by analyzing the C-tgδ diagrams can be complicated due to the simultaneous growth of these parameters, which contradicts the functional dependence between these parameters for the case of electrical insulation application of a parallel scheme for replacing the investigated capacitive object of control with dielectric losses. Taking into account the mentioned difficulties, in order to identify the presence of hidden oscillations in the obtained results, it is proposed to carry out a spectral analysis of numerical series. Using the example of harmonic signals, a method of interval estimation of the frequency of such hidden oscillations has been developed, which allows to reduce the influence of the spread of the spectrum of signals on the accuracy of estimation of their parameters. A spectral analysis of numerical series of the results of measuring the tangent of the dielectric loss angle was carried out and it was shown that the application of the proposed selection of frequencies of auxiliary trigonometric functions by which the investigated signal is decomposed allows to double the resolution of the Fourier transform without the traditional addition of zeros to the investigated numerical sequence and to halve the number of necessary calculations. by refusing to decompose the investigated signal using a complete system of orthogonal trigonometric functions. In the third section, a modification of the correlation method for measuring the phase shift was developed in order to improve the interference resistance of measurements of the tangent of the dielectric loss angle for control objects with a relatively low Q level. The developed modification requires calculations of several scalar products of the studied current and voltage signals with auxiliary trigonometric functions. The results of the comparative analysis of immunity showed that, compared to the traditional correlation method of measuring the phase shift, the developed modification made it possible to increase the immunity of the measurement of the phase shift between the current and voltage curves and, accordingly, the tangent of the dielectric loss angle in the range of values from 0º to 45º. At the same time, in the range from 45º to 90º, the classic correlation method of measuring the phase shift has a higher level of immunity compared to its developed modification. The fourth chapter analyzes the peculiarities of measuring the individual parameters of the dielectrics of each layer of insulation in three-core power cables with paper-impregnated insulation. The possibility of the existence of correlations between the results of measurements of the aggregate values of the electric capacity, which were obtained when using different methods of connecting the conductive elements of the power cable structure, is shown. The component variances of the results of the measurement of the partial insulation capacities of three-core power cables were analyzed and the formulas for the direct calculation of the values of the tangent of the dielectric loss angle using aggregate measurements were obtained. In the fifth chapter, based on the modified connection schemes of the conductive elements of the construction of the threewire power cable in a common metal sheath, a method of measuring the electrical capacity and tgδ of each of its insulation layers is developed. The developed modification of the existing inspection schemes provides for resistive or resistive-capacitive grounding of the tested insulation layer. Determination of unknown insulation parameters is carried out by adjusting the value of the electrical resistance through which the investigated insulation layers are grounded, until the moment of zero phase shift between the voltage on the investigated insulation layer and on its grounding elements, followed by the measurement of these voltages. In the sixth chapter, a theoretical analysis of the effect of the parasitic inductance of the investigated capacitive control object on the results of measuring the electric capacity and the tangent of the dielectric loss angle for the measurement circuit based on a voltage-to-current converter and a phase detector is carried out, solutions are given for the development of circuits for shifting the phase of harmonic signals by 90º , developed a methodology for estimating the parasitic inductance of capacitive control objects for their aperiodic discharge mode.
Опис
Ключові слова
реферат дисертації, старіння електричної ізоляції, паразитна ємність, паразитна індуктивність, цифрова обробка сигналів, сукупні вимірювання, контроль промислового обладнання, aging of electrical insulation, parasitic capacitance, parasitic inductance, digital signal processing, aggregate measurements, control of industrial equipment
Бібліографічний опис
Костюков І. О. Розвиток методів контролю технічного стану електричної ізоляції за параметрами ємності та тангенса кута діелектричних втрат [Електронний ресурс] : реф. дис. ... д-ра техн. наук : спец. 05.11.13 / Іван Олександрович Костюков ; Нац. техн. ун-т "Харків. політехн. ін-т". – Харків, 2023. – 38 с. – Бібліогр.: с. 32-35. – укр.