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State-of-the-Art Solutions and Innovations for Testing and Condition Monitoring of Power Transformers

A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "F: Electrical Engineering".

Deadline for manuscript submissions: closed (25 May 2023) | Viewed by 5632

Special Issue Editors

Department of Electrical Devices and High Voltage Technology, Lublin University of Technology, 38A Nadbystrzycka Street, 20-618 Lublin, Poland
Interests: diagnostics of power transformers; insulation condition diagnostics; failure prevention; environmental pollution; nanocomposite materials
Special Issues, Collections and Topics in MDPI journals
Department of Measurements and Applied Electrical Engineering; University of Zilina, 8215/1, Univerzitná Str., 010 26 Žilina, Slovakia
Interests: applied electrical engineering; diagnostics of power transformers; thermovision diagnostics of energy equipment; non-destructive testing methods

Special Issue Information

Dear Colleagues,

The Guest Editors are inviting submissions to a Special Issue of Energies on the subject area of “State-of-the-Art Solutions and Innovations for Testing and Condition Monitoring of Power Transformers”.

This Special Issue will focus on the wide-ranging diagnostics of power transformers, including the condition of the insulation, core, current feedthroughs, undervoltage regulators, cooling system, and other components. It will also concern metering, the application of sensors, and other solutions allowing for continuous monitoring of the condition of transformer elements. Conducting diagnostic tests makes it possible to eliminate damage to power transformer elements and determine its day-to-day, major overhaul, and out-of-operation dates. This can effectively reduce or even eliminate catastrophic failures and avoid the accompanying environmental pollution associated with, for example, insulating oil leakage.

Topics of interest for publication include, but are not limited to:

  • Diagnostics and monitoring of power transformers, including the condition of:
  • Insulation of transformers;
  • Oils and esters;
  • Solid isolation, including cellulose, aramid and others;
  • Windings;
  • Core;
  • Current feedthroughs;
  • Undervoltage regulators;
  • Cooling system, etc.
  • Experience with the application of modern diagnostic methods, including:
  • The FDS method;
  • The PDC method;
  • The RVM method;
  • The SFRA method;
  • Partial discharge measurements and localization of their places of occurrence;
  • Vibro-acoustic measurements;
  • Measurements of the acoustic method;
  • Development and implementation of new diagnostic methods, etc.
  • Experience with the renovation of transformers and the replacement of individual components, etc.

Prof. Dr. Tomasz Kołtunowicz
Dr. Milan Šebök
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Energies is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • power transformers
  • diagnostics of power transformers
  • insulation condition diagnostics
  • new diagnostic methods
  • failure prevention
  • environmental pollution caused by transformer damage

Published Papers (3 papers)

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Research

15 pages, 2164 KiB  
Article
Assessment Criteria of Changes in Health Index Values over Time—A Transformer Population Study
by Patryk Bohatyrewicz and Szymon Banaszak
Energies 2022, 15(16), 6078; https://0-doi-org.brum.beds.ac.uk/10.3390/en15166078 - 22 Aug 2022
Cited by 2 | Viewed by 1386
Abstract
The current use of health index algorithms is mainly limited to single assessments of the unit’s condition or the device comparison. The paper focuses on the changes in the health index values between the consecutive analyses. The algorithm used for this purpose was [...] Read more.
The current use of health index algorithms is mainly limited to single assessments of the unit’s condition or the device comparison. The paper focuses on the changes in the health index values between the consecutive analyses. The algorithm used for this purpose was previously developed by the authors. The test group included 359 complete oil evaluation results from 86 power transformers monitored over several years. For each outcome, the influence of the sub-components of the main score was calculated. Additional health index increase simulations were performed based on the IEC 60599 standard guidelines. The highest increases and decreases in the total score were listed and analyzed to determine the main factors behind the changes. The study has shown that the changes in dissolved gases concentrations have a much more significant influence on the health index values than the changes in physicochemical properties of the oil and furfural content. Based on the magnitude of the observed changes and the simulation outcomes, the authors have proposed two assessment thresholds—the 50th percentile health index increase within a population as an alarm zone, and the 90th or 95th percentile increase as a pre-failure zone. Full article
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16 pages, 1919 KiB  
Article
DC and AC Tests of Moisture Electrical Pressboard Impregnated with Mineral Oil or Synthetic Ester—Determination of Water Status in Power Transformer Insulation
by Pawel Zukowski, Przemyslaw Rogalski, Tomasz N. Kołtunowicz, Konrad Kierczynski, Marek Zenker, Alexander D. Pogrebnjak and Matej Kucera
Energies 2022, 15(8), 2859; https://0-doi-org.brum.beds.ac.uk/10.3390/en15082859 - 13 Apr 2022
Cited by 3 | Viewed by 1556
Abstract
In this study, the conductivity and permittivity of electrical pressboard—insulating liquid—water composites were investigated, and the electrical properties of the composites and water were analysed comparatively. Mineral oil and synthetic ester were used as insulating liquids. It was found that the presence of [...] Read more.
In this study, the conductivity and permittivity of electrical pressboard—insulating liquid—water composites were investigated, and the electrical properties of the composites and water were analysed comparatively. Mineral oil and synthetic ester were used as insulating liquids. It was found that the presence of water caused an increase in the permeability of the composite in the frequency range below 100 Hz. The value of static permittivity determined by water in the content of 5 wt. % was approximately 15. To obtain this value caused by liquid water, its volume should be approximately five (oil) and four times (ester) higher than its actual content, respectively. The determined values of the activation energy of the DC conductivity of the composites were several times higher than the values of the activation energy of the conductivity of the liquid water. The experimental values of the dielectric relaxation times were many orders of magnitude higher than the dielectric relaxation times of water. This means that the experimental results obtained for the dielectric permittivity, the activation energy of conductivity and the dielectric relaxation times for moisture electrical pressboard impregnated by mineral oil or synthetic ester exclude the possibility of the presence of liquid water in the composites. It was found that the conductivity of the composites increased exponentially with increasing water content. Such dependencies are characteristic of hopping conductivity, caused by the quantum phenomenon of electron tunnelling between nanometre-sized potential wells. As the increase in conductivity is determined by the presence of water in the composites, therefore, the nanometre potential wells were single-water molecules or nanodrops. Full article
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16 pages, 22766 KiB  
Article
Diagnostics of High Water Content Paper-Oil Transformer Insulation Based on the Temperature and Frequency Dependencies of the Loss Tangent
by Pawel Zukowski, Przemyslaw Rogalski, Vitalii Bondariev and Milan Sebok
Energies 2022, 15(8), 2813; https://0-doi-org.brum.beds.ac.uk/10.3390/en15082813 - 12 Apr 2022
Cited by 1 | Viewed by 1232
Abstract
The aim of the work was to prepare and test a paper-oil insulation system according to the recommendations of CIGRE (Conseil International des Grands Réseaux Électriques) with the parameters X = 50% and Y = 30%. Pressboard was moistened to a water content [...] Read more.
The aim of the work was to prepare and test a paper-oil insulation system according to the recommendations of CIGRE (Conseil International des Grands Réseaux Électriques) with the parameters X = 50% and Y = 30%. Pressboard was moistened to a water content of (5.0 ± 0.2) wt.% The loss tangent was measured using a DIRANA meter (FDS-PDC dielectric response analyzer) in the frequency range 10−4 Hz–5000 Hz for 6 temperatures from 293.15 K to 333.15 K with a step of 8 K. The waveforms simulated by the DIRANA software were fitted to the experimental dependence of the loss tangent. The fitting process was performed using two methods. In the first method, the measuring temperature value as well as X and Y values were entered into the software. The estimated moisture content of the insulation varied from about 1.4 to about 5.2 wt.%. The average value of moisture content was (3.73 ± 1.11) wt.%. In the second method, only the measuring temperature value was entered into the software. This improved the quality of matching. The estimated average moisture content was (5.83 ± 0.25) wt.%. It was found that the dimensions of the oil channel clearly affected the quality of the fitting process. By not taking into consideration real values of oil channel, the quality of the moisture content estimation was significantly improved. Full article
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