Author
S. I. Khrenov
Bio: S. I. Khrenov is an academic researcher from Moscow Power Engineering Institute. The author has contributed to research in topics: Voltage & Arc suppression. The author has an hindex of 4, co-authored 15 publications receiving 29 citations.
Topics: Voltage, Arc suppression, Pollution, Particle, Ground
Papers
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TL;DR: In this paper, the authors studied the working intensity of the electrical field in the cast epoxy insulation of a 6- to 110-kV switchgear taking into account its dimensions, structure, and basic operational factors.
Abstract: The method of choice of the working intensity of the electrical field in the cast epoxy insulation of a 6- to 110-kV switchgear taking into account its dimensions, structure, and basic operational factors is studied The volt–time characteristics of the electrical strength of the cast epoxy insulation corresponding to a low probability of the breakdown at the different intensity of the partial discharges are analyzed It is shown that the distribution of the electrical strength of the cast insulation under the short-term and long-term action of the commercial-frequency voltage is well described by the Weibull law and the influence of the dimensions on the electrical strength is specified by the “active” volume of the dielectric—the area where the electricalfield intensity makes up no less than 85% of the maximum in the clearance The estimation of the permissible field intensities in the cast insulation of a 10- to 35-kV switchgear with various degrees of the field inhomogeneity and intensities of the partial discharges is given
10 citations
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TL;DR: An experimental investigation of impulse transients in the windings of a full-scale mockup model of an active part of a 20-kV A SSVT with a rated voltage of 110 kV shows that, unlike in the case of power transformers with disc windings, more significant effects on the insulation are produced when no load is applied on the low-voltage windings.
Abstract: One of the key factors determining the performance of a 110–500-kV station service voltage transformer (SSVT) is a compact insulation design that provides minimum winding sizes. Since SSVTs are new equipment that combine the operational features of a power transformer and the design features of a measuring voltage transformer, it is necessary to study the characteristic transient processes occurring under the impact of lightning-impulse test voltages and lightning and switching overloads in operation in order to ensure proper insulation design. The article presents the results of an experimental investigation of impulse transients in the windings of a full-scale mockup model of an active part of a 20-kV A SSVT with a rated voltage of 110 kV. The influence of grounding the low-voltage winding terminals on the maximum values and duration of impulse stresses on the longitudinal insulation of the high-voltage winding is revealed. It is shown that, unlike in the case of power transformers with disc windings, more significant effects on the insulation are produced when no load is applied on the low-voltage windings.
4 citations
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TL;DR: A database of the generic solutions for protection from lightning was developed, it being a structured collection of files containing the layout of buildings and equipment at the substation and the arresters’ layout plan with taking into account the electromagnetic compatibility.
Abstract: A computer-aided design system (CAD) for the protection from lightning of the unit substations and overhead power lines was developed. A software package containing a calculation model of areas protected from direct lightning strikes, backflashover of the primary and secondary insulation, induced pulse voltage in the secondary circuits, protection from lightning of the power lines, and protection of power substations against the lightning overvoltage along with the overhead power lines was developed. A database of the generic solutions for protection from lightning was developed, it being a structured collection of files containing the layout of buildings and equipment at the substation and the arresters’ layout plan with taking into account the electromagnetic compatibility. A database for earthing arrangement of arresters is the structured set of the typical arresters earthing. In order to find the required generic solution, the user selects the desired file by parameters using the standard tools for working with Windows files. On the basis of the regulatory documents on system and software engineering, the procedure for verification of the computer programs, to be applied as a part of the CAD for the protection from lightning of substations and overhead power lines, was developed. The verification procedure is based on testing of computer programs, as part of the developed system, using test sets containing the test cases. Test cases and test sets for testing the computer programs were developed. The computer-aided design system (CAD) allows significantly reducing the cost for designing of the protection from lightning and improving the quality of the projects.
4 citations
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TL;DR: The use of rigid noncorona busbars with the air insulation, gas-filled current leads, and current leads with the polymeric insulation to connect various high-voltage elements at plants and substations allows providing a decrease in the electric energy losses, increase in reliability and safety of operation, as well as improving the ecological situation at the plants.
Abstract: The use of rigid noncorona busbars with the air insulation, gas-filled current leads, and current leads with the polymeric insulation to connect various high-voltage elements at plants and substations allows providing a decrease in the electric energy losses, increase in reliability and safety of operation, as well as improving the ecological situation at the plants and substations. Compactness of the busbars is provided due to the use of new insulation media (first and foremost, electrically high-strength gases and polymeric dielectrics), as well as improvement of the technology of production and use of these materials. At present, various types of high-voltage current leads are used: shielded air busbars, busbars with the cast polymeric insulation, and sealed shielded current leads with the basic high-strength gas insulation. Engineering solutions in which insulation media with low dielectric permeability are used and the buses are made noncorona with rated operating voltage are applied to reduce the losses in the busbars.
4 citations
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TL;DR: In this article, a general model that takes into account precipitation of particles, entering the ESP inlet (direct precipitation), as well as precipitation of reentrained particles (secondary precipitation), is presented.
Abstract: The majority of existing approaches to computation of electrostatic precipitator (ESP) efficiency do not take into account particle reentrainment from collecting electrodes. The first attempts to take into consideration particle reentrainment were made only recently. However, the existing reentrainment models for ESP are not sufficiently substantiated. A general model, which takes into account precipitation of particles, entering the ESP inlet (direct precipitation), as well as precipitation of reentrained particles (secondary precipitation), is presented in the paper. The model describes physical processes in an ESP using three integral parameters. These parameters are direct precipitation coefficient, secondary precipitation coefficient, and reentrainment coefficient, which is the ratio of reentrained particle flux to precipitation flux. An improved technique for computation of direct precipitation that takes into account particle charge distribution function is proposed. The influence of gas flow turbulence on charge distribution function parameters, as well as on other parameters of precipitation phenomena, is taken into account. The method has low computational costs. The secondary precipitation coefficient is also computed using this method. The most difficult task is calculation of the reentrainment coefficient. We suggest using data of periodical ESP testing to determine the reentrainment coefficient. The analysis of experimental data indicates that a fly ash layer on collecting electrodes is of paramount importance. It has been shown that the flux per unit length of particles falling into hoppers is proportional to weight (thickness) per unit length of the fly ash layer. Distributions of precipitation flux, flux into hoppers, reentrained particle flux along the ESP duct, and particle penetration through the ESP are computed using experimental data. A novel model that is based on a flux balance equation for each length element of an ESP duct is presented. The model has the form of a connection between physical phenomena that take place on two successive length elements of the collecting electrode. The model qualitatively agrees with experimental data. However, correction of the secondary precipitation coefficient and the reentrainment coefficient is required for quantitative agreement. In this regard, a model of layer growth and determination of functional relations between layer weight, hopper flux, and particle penetration play a key role.
4 citations
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TL;DR: In this paper, the results of a physical simulation using negatively charged artificial thunderstorm cells to test the spectrum of possible electromagnetic effects of upward streamer discharges on the model elements of transmission line monitoring systems (sensor or antennas) are presented.
Abstract: The results of a physical simulation using negatively charged artificial thunderstorm cells to test the spectrum of possible electromagnetic effects of upward streamer discharges on the model elements of transmission line monitoring systems (sensor or antennas) are presented. Rod and elongated model elements with different electric field amplification coefficients are investigated. A generalization is made about the parameters of upward streamer current impulse and its electromagnetic effect on both kinds of model elements. A wavelet analysis of the upward streamer corona current impulse and of the signal simultaneously induced in the neighboring model element is conducted. A generalization of the spectral characteristics of the upward streamer current and of the signals induced by the electromagnetic radiation of the nearby impulse streamer corona on model elements is made. The reasons for super-high and ultra-high frequency ranges in the wavelet spectrum of the induced electromagnetic effect are discussed. The characteristic spectral ranges of the possible electromagnetic effect of upward streamer flash on the elements of transmission line monitoring systems are considered.
6 citations
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TL;DR: Methods of reducing the computation time of the dynamic electro-geometrical model using two space volume definitions are examined, and the result shows that the definition of the space volume has impact on the interception efficiency, and also, the computationTime can be reduced by considering only space points within the attractive volume of the structure.
6 citations
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TL;DR: In this article, a remotely operated switchgear mounted directly on the trellis holding the conductors is used to reduce visual impact, land use and vulnerability of the system to weather adversity.
Abstract: Overhead high-voltage lines are a common choice for power transmission, but their planning, installation and management are often challenging tasks because of the surrounding public interest and of their importance as critical infrastructures. This is particularly true in the case of industrial installations requiring a high continuity of service. The working group formed by the University of Brescia (UniBS), the University of Padova (UniPD), and Torino Transmission Operating Area (AOT) of Terna Rete Italia S.p.A. (Terna) has studied an innovative solution featuring a remotely-operated switchgear mounted directly on the trellis holding the conductors. This strategy reduces visual impact, land use and vulnerability of the system to weather adversity, but noise exposure of the population requires appropriate study. This work introduces a new technical solution, discusses its benefits, and assesses the audible noise impact of the improved transmission line, considering the combined effect of switchgear action and corona discharge around the conductors. The sound emission data are fed as input into a sound propagation software enabling evaluating the noise perceived by people living in the neighborhoods. A mitigation solution is proposed and analyzed.
5 citations
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TL;DR: The problems of estimating the natural and dominating oscillation frequencies in SSVT windings and the voltages on the longitudinal insulation of SSVTWindings under the resonance conditions are considered and the proposed approach is applicable not only to SSVTs, but also to other types of transformer equipment.
Abstract: The design of new types of transformer equipment, in particular, station service voltage transformers (SSVTs), requires a detailed consideration of all technical aspects and conditions of their application and their design features. One problem is to provide their resistance to effects associated with their interaction with the grid. During transient events in the network caused by the operation of switching equipment or short circuits, the transformers are affected by the oscillating voltage, which, under certain conditions, can cause resonance overvoltages inside their windings. The design of SSVTs differs from that of common power transformers, mostly because different types of windings are used, which determines the essential difference in the natural oscillation frequencies and the theoretical possibility of the development of resonance overvoltages under changed combinations of network parameters and switching conditions. In this paper, the problems of estimating the natural and dominating oscillation frequencies in SSVT windings and the voltages on the longitudinal insulation of SSVT windings under the resonance conditions are considered. The proposed approach is applicable not only to SSVTs, but also to other types of transformer equipment.
5 citations
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06 Sep 2020TL;DR: In this paper, the preventive measures of transformer ferromagnetic resonance from the perspective of voltage harmonics and insulation coordination were proposed, based on the simulation analysis results of the simulation model, simulation algorithm, and waveform.
Abstract: Station Service Voltage Transformers (SSVT) combines the operating characteristics of power transformers and the design characteristics of measuring voltage transformers. Due to its lower initial cost and higher power supply reliability, its applications have been extended beyond that of auxiliary power. During transient events in the network caused by the operation of switching equipment or short circuits, the transformers are affected by the oscillating voltage, which, under certain conditions, can cause resonance overvoltage inside their windings. Based on the ATP-EMTP platform, the ferromagnetic resonance of SSVT is simulated and its simulation model, simulation algorithm, and waveform are analyzed. Based on the simulation analysis results, this paper puts forward the preventive measures of transformer ferromagnetic resonance from the perspective of voltage harmonics and insulation coordination.
3 citations