Power transformers and reactors

Highlights

The Study Committee A2 colloquium was held jointly with Study Committees B2 and D1. It was hosted by CBIP and CIGRE India in New Delhi on 21 and 22 November 2019. Opening addresses were given by a number of prominent industry figures from India, and also the Chair and Secretary of the Indian National Committee. A special opening address for Study Committee A2 was given by Mrs Seema Gupta, the Observer Member for India in Study Committee A2. She explained the main challenges facing transformer engineers in India.

Preferential Subject 1 for Study Committee A2 was “Advances in Transformer Design, including use of new materials”. The session co-chairs were Mr Jan Hayek and Mr Virenda Lakhiani. The keynote address was given by Mr Martin Stoessl, who emphasised some of the points made previously in the special opening address. A total of 13 papers were presented for this Preferential Subject. Subjects for the papers included applications and design concepts (3); improvements in transformer design (4); improvements in modelling (3); use of new materials (2); and risk assessment methodologies (1).
The session co-chairs selected the following as the best paper in this Preferential Subject: Patrice Hurlet, “Improvement of transformer specification to enhance reliability of key power transformers (GSU for nuclear power plants)”.
The following paper from this Preferential Subject was also highly commended by the Study Committee Chairman: Pramod Rao et al, “Transformer bushings: current technology trends, development and its relevance in monitoring bushings in service”.

Preferential Subject 2 for Study Committee A2 was “Quality Assurance and Short-Circuit Withstand Capability of Transformers”. The session co-chairs were Mr Henk Fonk and Mr RK Tiwari. The keynote address was given by Mr P Ramachandran, who used his experience to explain developments in the short-circuit withstand capability of transformers from 1885 to the present day. He suggested that short-circuit type test reports for power transformers should be valid for 10 years. He also suggested that transformer operators should consider ordering a short-circuit test for series of more than 10 transformers. A total of 8 papers were presented in this Preferential Subject. Subjects for the papers included improvements in transformer construction (2), improvements in transformer safety (1), and short-circuit withstand capability (5).
The session co-chairs selected the following as the best paper in this Preferential Subject: Professor Vasily Larin et al, "Russian practice on tests and confirmation of power transformers ability to withstand short-circuits”.

Preferential Subject 3 for Study Committee A2 was “Operational Experience in the Field of Transformers”. The session co-chairs were Dr Patrick Picher and Dr Aradhana Ray. The keynote address was given by Dr BN de Bhowmick, who gave more details on the main challenges facing transformer engineers in India and recent steps taken to meet them. A total of 10 papers were presented in this Preferential Subject. Most of the papers were on the subject of transformer field testing (7).
The session co-chairs selected the following as the best paper in this Preferential Subject: Professor Stefan Tenbohlen et al, “UHF sensor placement on power transformers for PD monitoring”.

Closing remarks were made by Mrs Seema Gupta, the Observer Member for India in Study Committee A2, and by Mr PP Wahi, Director of CBIP and CIGRE India. Special thanks were given to Mr Vishan Dutt of CBIP, for his role in organising the Joint Colloquium.

Working Groups in 2019

New Working Groups

The following four new Working Groups were created following the 2018 Paris session, and held their initial meetings during 2019:

• A2.60, “Dynamic thermal behaviour of power transformers”, convenor – Tim GRADNIK
• A2.61, “On-load tapchanger best practices”, convenor – Axel KRAEMER
• A2.62, “Analysis of ac transformer reliability”, convenor – Stefan TENBOHLEN
• A2.63, “Transformer impulse testing”, convenor – Ebrahim RAHIMPOUR

The following additional new Working Group was created during 2019, following publication of a Reference Paper in Electra 299 during 2018 which raised awareness of this subject: A2.64, “Condition of cellulose insulation in oil-immersed transformers after final dryout”, Convenor – Claes Bengtsson

A consultation was also held within the Study Committee on whether to establish a new Working Group to examine the subject of HVDC transformers in more detail, but it was decided that the time was not right for such a Working Groups.

WGs Disbanded

The following Working Groups and Joint Working Groups completed their work during 2019 and were disbanded:

• A2.43, “Transformer bushing reliability”, convenor Antun MIKULECKY
• A2/D1.46, “Field experience with transformer solid insulation markers”, convenor Jocelyn JALBERT
• A2.49, “Condition assessment of power transformers”, convenor Peter COLE
• D1/A2.47, “New frontiers of dissolved gas analysis (DGA) interpretation for power transformers and their accessories”, convenor Michel DUVAL

Total number of active, WGs, JWGs

The total number of Working Groups is 14, including 2 Joint Working Groups (with C4 and D1). There is also a special Task Force, continuing the work on solid insulation condition at end-of-life in power transformers begun by Joint Working Group D1/A2.47.

Publications

Working Groups and Joint Working Groups from the Study Committee published the following Technical Brochures during 2019:

 

Working Group A2.54 also published the following interim report: “Power Transformer Audible Sound Requirements”, in Electra 302.

Publication plan for the coming year

The following Working Groups and Joint Working Groups expect to make their final publications during 2020:

• Joint Working Group A2/C4.52, "High Frequency Transformer Models for Non-Standard Waveforms" (planned in five parts)
• Working Group A2.53, "Objective Interpretation Methodology for the Mechanical Condition Assessment of Transformer Windings Using Frequency Response Analysis"
• Working Group A2.56, “Power Transformer Efficiency”
• 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 “Electricity Supply 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 is expected to continue throughout 2020. It is hoped that the Green Book can be published at the start of 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 during 2020.

It is expected that Working Group A2.54 will present an additional interim report for publication in Electra during 2020.

Tutorials, webinars and workshops in 2019

The following tutorials were presented at the Study Committee A2 colloquium in New Delhi during November 2019:

• “Bushing Failure Mode Analysis”, presented by RK TYAGI on behalf of Working Group A2.43
• “Latest Trends / Advances in Transformer Design”, presented by Prof KULKARNI
• “[Transformer] Health Indexing”, presented by Tara-Lee MacARTHUR on behalf of Working Group A2.49

The following additional tutorial was presented by Study Committee A2 at the Study Committee A3 Colloquium, and regional seminar, in Bucharest during September 2019: “Transformer Post-Mortem Analysis”, presented by Simon RYDER on behalf of CIGRE Working Group A2.45.

The following tutorial was presented by Study Committee A2 at the Australia-Oceania Regional Committee meeting in Bali in March 2019: “Condition Assessment of Power Transformers”, presented by Paul GUY on behalf of CIGRE Working Group A2.49.

The following tutorial was presented jointly by Study Committees A2 and D1 at the International Symposium on High Voltage Engineering in Budapest during August 2019: “[Dissolved gas] monitoring systems”, by Jerzy BUCHAZ on behalf of CIGRE Joint Working Group D1/A2.47.

The following tutorials were presented by Study Committee A2 at the 5th International Colloquium on Transformer Research and Asset Management, organised by the Croatian National Committee, at Opatija during October 2019:

• “Transformer Post-Mortem Analysis”, presented by Andrew FIELDSEND-ROXBOROUGH on behalf of CIGRE Working Group A2.45
• “Condition Assessment of Power Transformers”, presented by Brian SPARLING on behalf of CIGRE Working Group A2.49

Planned in coming years

The Study Committee plans to present a tutorial on transformer diagnosis using Frequency Response Analysis, partly based on the work of Working Group A2.53 at the 2020 Paris Session.

Members of the Study Committee plan to present a number of other tutorials at different regional events during 2020.

Number of webinars presented in 2019

None organised centrally. Members of the Study Committee may have presented webinars on behalf of National Committees.

Strategic Plan (2018-2028)

The Strategic Plan was revised following the 2018 Paris session, to include the role of Additional Regular Members. It will be reviewed and revised by the incoming Chair after the 2020 Paris session.

Planned SC meetings (in 2021 and next)

The next planned Study Committee will take place at the Paris session in 2020.

The following planned Study Committee meeting will take place at the Study Committee colloquium in 2021. This will be taking place in Bucharest, and will be organised jointly with Study Committee B3.

In 2019

Eight different Study Committees, including Study Committee A2, supported the CIGRE – IEC Conference on EHV and UHV (ac and dc) at Hakodate in Japan on 24 and 25 April 2019.

Study Committee A2 supported the International Conference on Power Transformers “Transformer 19”. This was organised by the Polish Power Transmission and Distribution Association (PTPiREE) in Torun between 7 and 9 May 2019.

The Study Committee A3 colloquium was held with support from Study Committees A2 and B3. It was hosted by CIGRE Romania in Bucharest on 9 and 10 September 2019.

Study Committee A2 supported the 5th International Colloquium on Transformer Research and Asset Management. This was organised by CIGRE Croatia in Opatija on 10 and 11 October 2019.

The Study Committee A2 colloquium was held jointly with Study Committees B2 and D1. It was hosted by CBIP and CIGRE India in New Delhi on 21 and 22 November 2019.

In 2020 and beyond

The Study Committee colloquium in 2021 will be taking place in Bucharest, at the invitation of the Romanian National Committee. It will be organised jointly with Study Committee B3.

The Study Committee colloquium in 2023 will be taking place in Split, at the invitation of the Croatian National Committee.

Liaisons and Relations with other organisations

Relations with IEEE

There is a permanent liaison between the Study Committee and the IEEE Transformer Committee.

Relations with CIRED

There is no permanent liaison between the Study Committee and CIRED. A number of members of the Study Committee are active in CIRED.

Relations with IEC

The Chairman of IEC TC 14 (Power Transformers) 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) and TC 122 (UHV ac Transmission Systems).

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. New Working Groups are encouraged to recruit Young Members. The Study Committee also encourages Young Members to participate in events, and fully supports the Young Member Showcase at the Paris session.

The position of women engineers in the Study Committee is somewhat contradictory. The chair of CIGRE Women in Engineering, viz. Khayakazi DIOKA, is a member of the Study Committee. However, none of the Regular Members are women. This is likely to change when the membership of the Study Committee is renewed in 2020.

SC website & KMS

The Study Committee website was completely updated during 2019.
The Study Committee KMS workspace is updated several times monthly.

Contact

• Contact of the Chair and/or the Secretary of the Study Committee