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Vol. 18 (2015 year), No. 1
Kuklin D. V., Selivanov V. N.
Software for calculations of surge processes
in ground conductors and grounded objects
Software for calculations related to propagation of electromagnetic waves in high-voltage objects (transmission towers and their grounding, substation grounding) has been described in the paper. Using the software the oblique thin wire simulation method proposed by Guiffaut et al. (2012) has been verified for conductive medium
(in Russian, стр.6, fig. 5, tables. 1, ref 7, Adobe PDF, Adobe PDF 0 Kb)
Vol. 19 (2016 year), No. 4, DOI: 10.21443/1560-9278-2016-4
Selivanov V. N. , Danilin A. N., Zalesova O. V., Kolobov V. V.
Study of the frequency response of the mutual coupling between overhead lines
(in English, стр.9, fig. 6, tables. 0, ref 6, Adobe PDF, Adobe PDF 0 Kb)
Vol. 21 (2018 year), No. 4, DOI: 10.21443/1560-9278-2018-21-4
Kolobov V. V., Barannik M. B., Selivanov V. N.
A pulse generator with inductive energy storage for measuring the grounding resistance of transmission line towers
The pulse method may be used to measure the footing resistance of transmission towers with overhead grounding wires. Measuring systems that obtain the time dependent transient impedance may be used to measure the low-frequency resistance of transmission tower grounding devices. Current pulse generators with rectangular pulse shape are used in the measuring systems. The current pulses must have short rising time and constant magnitude during a measurement interval. Experimental investigations have shown that a pulse generator with inductive energy storage may be used in the measuring system. Generators with inductive energy storage have a number of advantages over pulse generators with capacitive energy storage. Namely, in case of unevenly distributed surge impedance along the current lead or in case of reflections from the remote end of the current lead an inductive generator allows to form a current pulse with a constant shape. Inductive pulse generators have high pulse energy. So, they may be used to measure the grounding resistance in high soil resistivity areas. Measuring systems based on an inductive storage pulse generator may be used not only to measure the footing resistance of transmission towers; they can also be used for experimental investigation of the effectiveness of lightning protection systems, in particular to obtain the parameters of RLC equivalent circuit of a single grounding device. Two possible topologies of an inductive pulse generator output stage have been considered in the paper. In the first case a step-up transformer is used as energy storage and an IGBT is used as opening switch. In another case an inductor is used as energy storage and MOSFETs are used as opening and closing switches. The experimental current waveforms for both types of generators have been given. They show that an inductor based pulse generator has better characteristics. Therefore it is preferred for this application.
(in Russian, стр.10, fig. 4, tables. 0, ref 13, adobePDF, adobePDF 0 Kb)
Vol. 21 (2018 year), No. 4, DOI: 10.21443/1560-9278-2018-21-4
Selivanov V. N., Barannik M. B., Bilin V. A., Efimov B. V., Kolobov V. V., Sakharov Ya. A.
Analysis of long-term monitoring of autotransformer neutral currents
The Kola Science Center of the Russian Academy of Sciences together with the Polar Geophysical Institute is carrying out research concerning the effect of geomagnetic storms on the state of electrical networks and transformer substations on the Kola Peninsula and in Karelia. A regional system for monitoring currents in transformer neutral was created which collected a huge array of information on the influence of geomagnetic disturbances on a 800 km electric network. Overhead transmission lines are giant antennas that capture electromagnetic energy of any nature from the surrounding space. An analysis of the data accumulated over many years shows that in the current of a grounded neutral there are reliable responses to a wide range of electromagnetic phenomena on the Earth and in the near-Earth space: pulsed and quasisinusoidal pulsations of the geomagnetic field, extremely-low frequency components of artificial signals, lightning discharges and internal transients in the power system. To identify phenomena, a visual method is used to analyze the time and spectral characteristics of signals, which takes a long time and is rather subjective. There is always the possibility that some important, previously unidentified phenomena will go unnoticed. The paper describes the characteristic features of signals detected in neutral currents of power transformers. Algorithms of digital signal processing that can be used to create programs for automatic analysis of large data sets have been considered. To the greatest extent, numerical methods based on wavelet expansion and Fourier transform are suitable for studying nonsteady signals of a complex structure.
(in Russian, стр.8, fig. 6, tables. 0, ref 7, adobePDF, adobePDF 0 Kb)