Power transformers and reactors
by Pascal Mueller, Chair & Marc Foata, Secretary
Highlights
2020 has been a very challenging year for society around the World. CIGRE activities, including those of Study Committee A2, have been affected by the current situation. Many CIGRE and other industry events have been cancelled, postponed, or have been organised on-line. Many working and advisory groups have also changed from face-to-face meetings to on-line meetings.
The highlight of 2020 for Study Committee A2 was the virtual Paris session. The paper presentation session was chaired by the outgoing Study Committee Chairman, Simon RYDER, and the incoming Study Committee Chairman, Pascal MÜLLER. They were assisted by the outgoing Study Committee Secretary, Tim GRADNIK, and the incoming Study Committee Chairman, Marc FOATA. They were also assisted by Grégoire AMATO from Central Office.
The special reporters were Thomas Herskind OLESEN for preferential subject 1 (Transformer technologies to enable integration of distributed renewable energy resources); Alvaro PORTILLO for preferential subject 2 (Advances in dielectric design and testing); and Janine JAGERS and Stefan TENBOHLEN jointly for preferential subject 3 (Improving reliability for transformers).
A total of 11 papers were accepted for preferential subject 1 (Transformer technologies to enable integration of distributed renewable energy resources), of which 10 were presented. The keynote address was given by Michael HEINZ. A young member showcase presentation was made by Burak ESENBOGA on the subject of “Dynamic modelling and analysis of a solid-state transformer for integration of high-power solar PV plant”. The Special Reporter selected paper A2-101 “Distributed Energy Resources: Impact of reverse power flow on transformers” by Parag UPHADAY et al as the best paper submitted in preferential subject 1. This was subsequently selected by the editor of CIGRE Science and Engineering as the best paper submitted to the Study Committee A2 overall and was republished in CIGRE Science and Engineering in October 2020.
A total of 8 papers were accepted for preferential subject 2 (Advances in dielectric design and testing), of which 6 were presented. The keynote address was given by Daniil MATVEEV. A young member showcase presentation was made by Oasis SANCIBRIAN on the subject of “Analysis of the impregnation process of cellulosic materials by ester-based insulation fluids”. The Special Reporter selected paper A2-208 “Verification of withstand capability for very fast transients of a 200MVA 500kV [generator] transformer by modelling and testing” by Alexander RABEL et al as the best paper submitted in preferential subject 2.
A total of 23 papers were accepted for preferential subject 3 (Improving reliability for transformers), of which 20 were presented. The keynote address was given by Dan MARTIN. A young member showcase presentation was made by Sam McCORMICK on the subject of “Using machine learning to quantify the impact of weather on transformer failure risk”. The Special Reporters selected paper A2-307 “Improving the reliability of key power transformers through specifications” by Patrice HURLET et al as the best paper submitted in preferential subject 3.
The Technical Council Award for Study Committee A2 in 2020 has been given to Michel DUVAL of Canada for outstanding work of many years on dissolved gas analysis for transformer fault diagnosis. His contribution has greatly influenced the use of dissolved gas analysis as a standard method for condition monitoring and the “Duval triangle” has become an important tool for the analysis of results. He has also helped establish typical gas levels and typical rates of gas formation for power transformers.
Working Groups in 2020:
New WGs
Joint Working Group D1/A2.77 on liquid tests for electrical equipment was created in March 2020, to continue the work of D1/A2.47 on advances in dissolved gas analysis.
WGs Disbanded
Working Group A2.53 on interpretation of winding frequency response measurement results completed its work and was disbanded. It is expected that Working Group A2-59 on transformer on-site assembly, rebuild, and heavy-duty testing will complete its work and be disbanded at the start of 2021.
Due to insufficient participation, Working Group A2.61 on OLTC best practices has been disbanded following the recommendation of the convenor Axel Krämer.
Total number of active, WGs, JWGs
The total number of Working Groups supported by Study Committee A2 is 14, including 2 joint Working Groups (with Study Committees C4 and D1).
Number of WG meetings held by electronic means (video or phone conferences)
Most Working Groups supported by Study Committee A2 have been unable to hold face-to-face meetings and have therefore replaced these with virtual meetings. In most cases virtual meetings are shorter than face-to-face meetings, but take place more frequently. As an example, Working Group A2.58 on transformer installation, pre-commissioning, and trial operation held 7 virtual meetings between April and December 2020 following cancellation of 2 scheduled face-to-face meetings.
CIGRE active Working Groups / Call for experts
Publications
Working Groups supported by the Study Committee published the following Brochures during 2020:
The following interim reports and reference papers were published in Electra during 2020:
Publication plan for the coming year
CIGRE activities, including those of Study Committee A2, have been affected by the current situation. There have been delays in a number of planned publications. The following Working Groups supported by Study Committee A2 are expected to publish their final reports during 2021:
- Joint Working Group A2/D1.51: “improvements to PD Measurements for Factory and Site Acceptance Test of Power Transformers”
- Joint Working Group A2/C4.52: "High Frequency Transformer Models for Non-Standard Waveforms" (planned in five parts)
- Working Group A2.55: “Life Extension of oil filled Transformers and Shunt Reactors”
- Working Group A2.56: “Power Transformer Efficiency”
- Working Group A2.58: “Installation, Pre-Commissioning, and Trial Operation of Power Transformers”
- Working Group A2.59: “On-Site Assembly, On-Site Rebuild, and On-Site High Voltage Testing of Power Transformers”
Green Books progress
In common with all other Study Committees, the Study Committee contributed a chapter to the Green Book on the “Power System of the Future”.
It was decided at the 2018 Paris session to write a Green Book on the transformer procurement process. The contents of this Green Book will be based largely on the work of current and recent Working Groups (A2-36, A2-42, A2-56, A2-58, and also A2-59). The proposal was approved at the start of 2019. Editorial work continued throughout 2019 and 2020. It is expected that the Green Book will be published during 2021.
Reference papers progress
The members of Joint Working Group D1/A2.47 raised some important questions about solid insulation condition at end-of-life in power transformers. As this was not part of their original terms-of-reference, it was agreed that a special task force should be created including some members of the Joint Working Group and also some other experts. This has been established under the leadership of Christoph KRAUSE, and is expected to present a reference paper for publication in Electra in early 2021.
Tutorials and workshops in 2020
CIGRE activities, including those of Study Committee A2, have been affected by the current situation. The number of tutorials presented has been sharply reduced compared with previous years. The following tutorial was presented at the virtual Paris session:
“Transformer FRA Interpretation”, by Mark LACHMANN, Patrick PICHER, and Stefan TENBOHLEN on behalf of Working Group A2.53
Strategic Plan (2018-2028), SC Structure and Action Plan:
The incoming chairman, Pascal MUELLER, has made some changes to the organisation of the Study Committee with the creation of two new advisory groups – on digitalisation and on lower voltage applications. The incoming chairman has also produced a revised Strategic Plan for the 2020-2030 period which is posted on the SC A2 public website.
Planned SC meetings (in 2022 and next)
The next Study Committee meetings will be taking place during the 2021 Centennial Paris session and the 2022 regular Paris session. It is expected that Study Committee meeting in 2023 will take place at the Study Committee colloquium in Croatia.
Participation to Regional Meetings, colloquia and symposia:
In 2020 (passed)
CIGRE activities, including those of Study Committee A2, have been affected by the current situation. The only major event supported by CIGRE Study Committee A2 during 2020 was the virtual Paris session. A number of other major events were postponed from 2020 to 2021.
In 2021 and beyond (scheduled)
CIGRE Study Committee A2 expect to be supporting the following major events during 2021:
- Centennial Symposium, Ljubljana (Slovenia), June 2021
- Centennial Paris session, Paris (France), August 2021
- CMDM conference, Bucharest (Romania), October 2021
- CIGRE-SEERC conference, Vienna (Austria), November 2021
- CIGRE Workspot, Foz do Iguacu (Brazil), November 2021
The Study Committee colloquium in 2023 will be taking place in Croatia.
Liaisons and Relations with other organisations
Relations with IEEE
There is a permanent liaison (Craig SWINDERMAN) between the Study Committee and the IEEE Transformer Committee.
Relations with CIRED
There was previously no permanent liaison between the Study Committee and CIRED. The new Advisory Group (Convenor Peter WERLE) on lower voltage applications will aim at establishing better collaboration with CIRED.
Relations with IEC
The Chairman of IEC TC 14 (Power Transformers – Christoph PLOETNER) is ex officio a member of the Study Committee. There are also permanent liaisons between the Study Committee and IEC TC 10 (Fluids for Electrotechnical Applications – Peter WERLE) and TC 122 (UHV ac Transmission Systems – Yukiyasu SHIRASAKA).
Specific actions for the recruitment of young experts, Place of Women in the SC
Young Members continue to make an outstanding contribution to the work of the Study Committee. Tara-Lee MacARTHUR was given a Young Member award for her contribution at the 2020 virtual Paris session. The Study Committee also encourages Young Members to participate in events, and included a Young Member showcase in each preferential subject at the 2020 virtual Paris session.
The position of women engineers in the Study Committee has improved substantially during 2020 with the appointment of more women regular, additional regular, and observer members than ever before. The chair of CIGRE Women in Engineering, viz. Khayakazi DIOKA, is a member of the Study Committee and was appointed as chair of one of the advisory groups during 2020.
SC website and KMS
The Study Committee has appointed Stefan JAUFER as webmaster during 2020 to improve its on-line presence. The Study Committee website and KMS space are updated at regular intervals.
Contact
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