Ivanovo State Power University

About: Ivanovo State Power University is a education organization based out in Ivanovo, Russia. It is known for research contribution in the topics: Thermal power station & Chemistry. The organization has 143 authors who have published 76 publications receiving 165 citations. The organization is also known as: Ivanovo State Power University named аfter V. I. Lenin.

Experimental determination of partial discharges in a model of a digital instrument transformer by differential method

Abstract: Power facilities are now implementing the concept of smart grid and its essential elements – high-voltage digital current and voltage transformers. However, the implementation of digital technologies is slowed down by the lack of operation experience and reliability indicators. One of the main causes of high-voltage equipment failures is insulation damage. The most informative parameters determined by insulation evaluation are partial discharge characteristics. There are rated values of these characteristics for rotating electrical machines and power transformers measured by external equipment. But the existing method of partial discharge analysis cannot be applied to digital current and voltage transformers as there are no criteria for tripping of the innovative equipment with comprehensive insulation. All this urges us to study the possibility to determine experimentally the characteristics of partial discharges in the insulation of digital current and voltage transformers by using embedded inductive sensors in order to develop a method for condition monitoring of digital current and voltage transformers and improving of their reliability. In this work, we have used a model of digital current and voltage transformers, a high-voltage test unit, a digital multi-input oscciloscope and inductive sensors. The experiment includes: detecting partial discharges in the model of digital current and voltage transformers by the external bridge connection, recording the voltage at which partial discharges occur in the simulated fault area, measuring the corresponding value of the apparent charge of the partial discharge, detecting partial discharges in the model of digital current and voltage transformers by a differential method with the help of embedded inductive sensors. The characteristics of partial discharges in the simulated fault area have been experimentally determined on a model of digital current and voltage transformers. The pulse voltage on the embedded inductive sensor corresponding to the apparent charge of 80 pC was equal to 600 mV at the test voltage of 2,7 kV. Embedded inductive sensors allow implementing the method of insulation condition monitoring for digital current and voltage transformers in accordance with the partial discharge characteristics both at the stages of production and operation extending the potential of the electronic (microprocessor) module and increasing the reliability of digital current and voltage transformers.

Method of condition monitoring of rotor windings of the medium voltage induction motors of power plant auxiliaries in start-up modes

Abstract: A promising method of monitoring rotor winding condition of induction electric motors ensuring higher reliability of their operation is spectral analysis of the external magnetic field signal. Modern methods of external magnetic field analysis use only the spectrum of this signal in the steady-state operation mode, which does not allow effective monitoring on a number of medium voltage electric motors of power plant auxiliaries operating with long start-ups (for example, machines with variable load, with a double squirrel cage, etc.). It is possible to evaluate the rotor winding condition of such machines in start-up modes, which means that an important task is to study the frequency-time spectra of the external magnetic field of the above-mentioned electric motors and to develop a method for monitoring the state of their rotor windings in the startup mode. In the study, the authors used two-dimensional models of two different types of motors representing drives of the mechanisms of draft systems at power stations. Both models are developed in the ANSYS software package. The calculation of the external magnetic field was carried out using the finite element method. The modelling was done for cases with or without defects. Signal processing was per-formed using the Fourier window transform method in the MatLab software package. Frequency-time spectra of the external magnetic field were built in the start-up mode on models of the investigated induction motors with the following defects: with dynamic eccentricity, with one broken bar of the rotor winding and without the indicated defects. The research results allowed us to develop a method for monitoring the rotor winding state of medium voltage electric motors of power plant auxiliaries operating with long start-ups. The method is based on detecting lower side frequencies of the fictitious rotor winding harmonics in the frequency-time spectrum during the startup. Their specific feature is «reflection» in the spectrum from the time axis. The developed method of monitoring rotor winding condition of the above-mentioned induction electric motors allows increasing the reliability of their operation by timely detection of faults in the rotor windings.

Electrochemical properties of LiAsF6 solutions in low-polar aprotic solvents

Abstract: The electrochemical behavior of the concentrated solutions of lithium hexafluoroarsenate in tetrahydrofuran and methyl acetate, having low dielectric constants, was studied. Their high specific conductivity compared with solutions of this ionophore in highly polar solvents (propylene carbonate, γ-butyrolactone) may be due to the additional contribution from the charge transfer by the ionotropic mechanism. Voltammetric curves were obtained on a platinum electrode for LiAsF6 solutions in tetrahydrofuran and methyl acetate. The efficiency of lithium cycling in the systems was evaluated.

Research on the Metrological Characteristics and Voltage Transformer with Open Core Antiresonance Properties

Abstract: This work presents research results of open core high-voltage instrument transformers. The authors proposed different transformer constructions (designs) and implemented mathematical modeling on the basis of specially developed computer models carrying out field and circuit calculations simultaneously. According to the calculation results, the investigated voltage transformer amplitude and phase errors are defined. Also, research results of the investigated transformer antiresonance properties on the basis of symbolic models are given.

Principle of Compatibility of Heterogeneous Additives in Triboactive Metalworking Fluids for Edge Cutting of Metals

Abstract: The problem of the combined usage of surface and chemically-active additives within metalworking fluids (MWF) for edge-cutting processing has been studied. The test results of MWFs containing surface-active additives with oxygen-containing reactive components have been demonstrated. The hypothesis of the special structure of boundary lubrication layers formed by two triboactive components of different chemical nature has been defined.