1. Presentation of CIGRE activities Chairman SC A2 "Transformers"
CONSEIL INTERNATIONAL DES GRANDS RESEAUX ELECTRIQUES INTERNATIONAL COUNCIL ON LARGE ELECTRIC SYSTEMS   STUDY COMMITTEE A2 TRANSFORMERS
Presentation of CIGRE activities
on Power Transformers
C. Rajotte (CA)
Chairman SC A2 "Transformers"

2. The Transformer Committee (SC A2)
Scope
Design, construction, manufacture and operation for all kinds of power transformers, including industrial , DC converters and phase-shift transformers and for all types of reactors and transformer components (bushing, tap-changer…)
In the past ( known as SC12 ) activities were focussed on design problems related to the rapid increase of rated voltage and power
Today's SC A2 Key Domains
Design, manufacturing & testing
Specifications, procurement & economics
Operation, reliability, safety & environment
Maintenance, diagnostics, monitoring, & repair
Life cycle
Transformer technology
Transformer utilisation
Chairman: Claude Rajotte (CA) Secretary: Patrick Picher (CA)

3. Present SC A2 Activities
24 regular members
19 observer members
10 WG's and 5 JWG's
More than 350 experts from more than 40 countries
5 AG’s

4. Present SC A2 Working Groups
WG A Guide on transformer Transportation (A. Mjelve/NO)
Typical conditions/forces during transport
Specifications and design review
Requirements on transportation issues
WG A2.43 Transformer bushings reliability (A. Mikulecky/HRvatska)
• Bushing failure definition
• Failure mechanisms for OIP, RBP, RIP
• Bushings failure rate
• Predicted life time, maintenance, diagnostic

5. Present SC A2 Working Groups
WG A2.45: Transformer Failure Investigation and post-mortem Analysis (M.C. Lessard/CA)
Important information to collect
Availability and significance of design data
Documentation during the dismounting
Paper sampling: how, where, precautions
JWG A2/D1.46: Field experience with transformer solid insulating ageing markers (R. Mertens/BE)
Field cases: correlation between chemical markers and DP
Design information relevant to ageing markers models
Consideration of operation and maintenance records
Influence of oil sampling conditions (ex: temperature)

6. Present SC A2 Working Groups
JWG D1/A2.47: New frontiers of Dissolved Gas Analysis (DGA) interpretation for power transformers and their accessories (M. Duval/CA)
Review progress in the field of DGA
Significance of CO, CO2 and CO2/CO for detecting paper involvement in faults
Case studies and suggestions for typical problems and actions initiated by DGA interpretation
WG A2.49: Condition Assessment of Power Transformers (P. Cole/AU)
Review existing CIGRE documents and literature
Determine key parameters and how these parameters can be combined to determine health index
Consideration should be given to both deterministic and probabilistic methods.
Provide details of health indexes/condition assessment tools currently in use

7. Present SC A2 Working Groups
WG A2.50: Effect of the distributed energy sources and consequent induced reverse power flow (step up) on transmission and distribution transformers (J.C. Riboud/FR)
Effect of step up operation on transformers that were not designed for this purpose.
Effect on flux density, temperature rise, noise and other performances
Possible tap changer control problems
consequences for core flux and voltage regulation

8. Present SC A2 Working Groups
JWG A2/D1.51: Improvement to Partial Discharge Measurements for Factory and Site Acceptance Tests of Power Transformers (S. Coenen/DE)
Discussion and Comparison of given methods in international standards
Discussion and Evaluation of alternative methods
Recommendations for improved PD Factory/Site Acceptance Tests
JWG A2/C4.52: High-frequency transformer models for non-standard waveforms (B. Gustavsen/NO)
Provide guidelines and recommendations for the generation of transformer models for simulation of high-frequency transient overvoltages that can occur in actual service.
Define minimum requirements that models supplied by manufacturers to customers must comply with for including the transformer model in network studies.
Provide benchmark examples of models applied in simulation of transformer-network transient interactions using white-box and black-box models.

9. Present SC A2 Working Groups
WG A2.53: Objective interpretation methodology for the mechanical condition assessment of transformer windings using Frequency Response Analysis (P. Picher/CA)
Review of the state-of-the-art of quantitative interpretation methodologies.
Use of high frequency transformer modelling, real case studies or a combination of both.
Discuss the applications for such methodologies and make recommendations for best practices and possible standardisation.
JWG A2.54: Power transformer audible noise requirements (C. Ploetner /DE)
Description of basic sound development mechanisms - distinguish between no-load and load condition and cooling system.
Development of sound level ranges for all three components per transformer class. 1Ɵ/3Ɵ/50Hz / 60Hz
Summary information on sound mitigation (mounting, panels, enclosures, walls around units)

10. Present SC A2 Working Groups
WG A2.55: Life Extension of oil filled Transformers and Shunt Reactors (P. Mueller/CH)
Define means to extend service life of a unit which is aged but in good enough condition while ensuring the required level of reliability at a targeted cost;
Mitigation solutions to keep a failing unit in service until a planned replacement.
JWG A2.56: Power transformer efficiency (Zarko Janic/DE)
Economic and environmental impact of regulations on efficiency
Transformer losses and strategies for their optimization
Loss level specifications and loss evaluation used in tenders by utilities
Experience with energy efficiency improvement, regulation and technology.
Impact of higher efficiency on transportability of transformers
Cost/benefit analysis for further efficiency improvement

11. Present SC A2 Working Groups
WG A2.57: Effects of DC Bias on power transformers (D. Susa/NO)
State of the art (phenomena, sources, application to transformer, case studies, scenarios)
Effect on power transformers (harmonic generation, VAr consumption, noise, losses, temperatures/overheating, failure modes)
Calculations, modelling, model verification
Requirements for transformer specification and design review
Methods to prove the withstand capability
Design and technology susceptibility

12. Recent CIGRE SC A2 BROCHURES
Scope Ref Year
Transformer Thermal Modelling
Technology & Util. of Oil Insul. HV Sh. Reactors
Oil conductivity under DC condition
Transformer Reliability Survey
Guide on Transf. Intelligent Condition Monitoring
Copper Sulphide Long Term Mitig.&Risk asses
Transient Interac. Transformers&Power System
Guide for Specifications
Guide for Design Review
Guide for Factory Capability Assessment
Guide for Fire Safety
Guide on Transformer Maintenance
HVDC Tr. – Test, ageing, reliability in service
HVDC Tr. – Guidelines for design review
Experience in service with new insulating liquids

13. Recent and Future SC A2 Sessions & Colloquium
2014 Paris Session
- Best practices for transformer asset management
- Transformers for specialized applications
- Field experience with the use of non-conventional materials and technologies
2015 Shanghai Colloquium
- EHV/UHV and EVHDC/UHVDC Transformers and its components
Equipment technologies for substations of the future and Smart Grid - in collaboration with SC A3 and SC B3
Making the Best use of the Existing transformer fleet
2016 Paris Session
- Advances in transformer diagnostic and monitoring
- EHV / UHV and EHV DC / UHV DC Transformers and their components
- Transformer windings
2017 Cracow Colloquium
Subjects to be determined

14. Thank you for your attention