THE USE OF DISCRETE WAVELET ANALYSIS OF VIBRO-ACOUSTIC SIGNALS TO DETECT THE POWER SUPPLY ASYMMETRY OF ROTATING ACCOMPANYING ELECTRIC MACHINES
Graniak Valeriy Fedorovich - Candidate of Science (Engineering), Associate Professor, Associate Professor of the Department of Power engineering, electrical engineering and electromechanics of Vinnitsa National Agrarian University . (3 Soniachna St., Vinnitsa, Ukraine, 21008, e-mail: firstname.lastname@example.org)
Gaidamak Oleg Leonidovich - Candidate of Science (Engineering), Associate Professor, Associate Professor of the Department of Power engineering, electrical engineering and electromechanics of Vinnitsa National Agrarian University . (3 Soniachna St., Vinnitsa, Ukraine, 21008, e-mail: email@example.com)
The work shows that among the existing sufficiently described and studied approaches that are suitable for analyzing the temporal realization of a vibosignal, which can be obtained during the operation of a real electric machine, one can single out Fourier transforms and discrete wavelet transformations. An analysis of the descriptions of vibro-acoustic signals given in the literature, caused by the asymmetry of the power supply, shows that this defect leads to the appearance of oscillations that contain a harmonic component localized at the frequency of the supply voltage of the electrical network. This fact justifies the expediency of analyzing the frequency range, which includes the frequency of the supply voltage, and the selection of the mother wavelet, based on the features inherent in a single harmonic oscillation.
A method for detecting a defect in the asymmetry of power supply to rotating electric machines of alternating current using a discrete wavelet transformation of a vibro-acoustic signal is proposed. The frequency band has been established, which is advisable to analyze in order to identify the indicated defect.
It was found that the detection of a power asymmetry defect with the use of the wavelet transform of the temporal realization of the vibroacoustic signal is advisable to carry out using the Haar maternal wavelet function, which provides a combination of a high degree of affinity of the maternal wavelet with the form of vibration change due to the introduced asymmetry and relative the simplicity of such a transformation.
It is shown that when detecting power asymmetry, it is advisable to analyze the behavior of the wavelet coefficients of the frequency band, which includes the frequency of the supply voltage of the electric machine. Since the influence of the indicated defect on other frequency bands will be minimal, the analysis of the behavior of their wavelet transform coefficients in order to identify the indicated defect is ineffective.
A numerical criterion for assessing the influence of power asymmetry on the wavelet transform coefficients is proposed in the form of the mean square value of the wavelet coefficients of the informative frequency band in the study of the time interval, which significantly exceeds the period of the supply voltage of the electric machine. It is shown that this criterion has a reduced sensitivity to the impact of non-informative single disturbances that may arise during the operation of an electric machine. Keywords: electric machine, rotor unbalance, defect, burst, wavelet transform.
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The journal "Vibrations in engineering and technology" presents materials on the following issues
• Theory of processes and machines
• Mechanical Engineering and materialprocessing
• Processing and food production
The certificateof massmediaState registration:kv no 16643-5115 from 30.04.2010 .
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In June 1994 the 2nd International Scientific and Technical Conference "Application of vibrations for technological purposes" was organized on the basis of Vinnytsia State Agricultural Institute. Leading experts in this field, noting the significant contribution to the school of Vibration Engineering under the leadership of P. S. Bernyk, proposed to create a professional all-Ukrainian scientific and technical journal "Vibration in engineering and technology..The journal was foundedat Vinnytsia State Agricultural Institute and P.S. Bernyk was elected to be the chief editor .
For all these years (since 1994) theJournal "vibration in engineering and technology" published 94 issues wherestudy of vibration effects, the creation of progressive energy saving technologies and equipment for their implementation were highlighted.
Currently Kaletnik H.M PhD , professor, academician NAAS is the chief editor of the "Vibrations in engineering and Technology"
The journal "Vibration in Engineering and technology", which has no analogues on the territory of Ukraine, is well known abroad.