37. саветовање CIGRE Србија (2025) СИГУРНОСТ, СТАБИЛНОСТ, ПОУЗДАНОСТ И RESILIENCE ЕЛЕКТРОЕНЕРГЕТСКОГ СИСТЕМА МУЛТИСЕКТОРСКО ПОВЕЗИВАЊЕ У ЕНЕРГЕТИЦИ И ПРИВРЕДИ – A2.03
АУТОР(И) / AUTHOR(S): Dejan Kolarski, Jelena Lukić, Valentina Vasović, Jelena Janković, Draginja Mihajlović, Ivan Mitrović, Milan Đorđević
DOI: 10.46793/CIGRE37.A2.03
САЖЕТАК / ABSTRACT:
The presence of elemental sulfur in transformer insulating fluids, even in trace amounts, leads to the formation of electrically conductive silver (I) sulfide at low operating temperatures, posing a significant threat to on-load tap changer (OLTC) contacts. The International CIGRE organization currently has an active task force addressing the issue of silver corrosion in transformers (CIGRE A2 Task Force on Silver Corrosion). The focus is on investigating the origin of corrosive sulfur compounds in mineral insulating oils and esters, detection methods, case studies, risk assessment, and mitigation strategies. Insulating fluids (mineral oils or synthetic esters) are tested for corrosive sulfur compounds using standardized corrosion tests (ASTM D1275, DIN 51353) and quantitative sulfur analysis (IEC 62697-1, IEC 62697-2, IEC TR 62697-3). To enhance silver corrosion assessment, a new testing method was developed at the institute, improving upon existing ASTM and DIN standards. As part of the GreenCleanS project, funded by the Science Fund of the Republic of Serbia, an innovative desulfurization technology was successfully implemented at Thermal Power Plant Kolubara A located in Veliki Crljeni, treating 1.500 liters corrosive oil with elemental sulfur. During the technology demonstration at the Kolubara A Power Plant, process parameters were monitored, and environmental impact was assessed. The results indicated that the measured values are within permissible limits, leading to the conclusion that the developed technology is clean, environmentally enclosed, and aligned with the principles of Best Environmental Practices (BEP). Oil analysis after desulfurization in real operating conditions confirmed the effective removal of elemental sulfur below the quantification limit, with improved physical-chemical and electrical characteristics of oil. These findings highlight the high potential of the developed process for industrial applications.
КЉУЧНЕ РЕЧИ / KEYWORDS:
elemental sulfur, corrosive sulfur, insulating fluids, power transformer, GreenCleanS, innovative technology
ПРОЈЕКАТ / ACKNOWLEDGEMENT:
Istraživanje sprovedeno uz podršku Fonda za Nauku Republike Srbije, broj projekta 6700, Development of green technology to mitigate power transformer failures induced by elemental sulphur and change current hazardous practice in transformer oil regeneration – GreenCleanS.
Iskreno se zahvaljujemo akcionarskom društvu „Elektroprivreda Srbije” i Termoelektrani Kolubara A na velikodušnoj podršci i izuzetnoj saradnji tokom realizacije GreenCleanS projekta.
ЛИТЕРАТУРА / REFERENCES:
- Holt A. F.; Facciotti M.; Amaro P.; Brown R. C. D.; Lewin P. L.; Pilgrim J. A. Silver Corrosion in Transformers. Published in: 2013 Annual Report Conference on Electrical Insulation and Dielectric Phenomena, Chenzhen, China, 20-23 October 2013, IEEE
- F. Scatiggio, V. Tumiatti, R. Maina, M. Tumiatti, M. Pompili, and R. Bartnikas. Corrosive sulfur in insulating oils: Its detection and correlated power apparatus failures. Power Delivery, IEEE Transactions on, 23(1):508 –509, jan. 2008.
- Holt, A.F.; Facciotti, M.; Amaro, P.; Brown, R.C.D.; Lewin, P.L.; Pilgrim, J.A.; Wilson, G.; Jarman, P. An initial study into silver corrosion in transformers following oil reclamation. In Proceedings of the 2013 IEEE Electrical Insulation Conference (EIC), Ottawa, ON, Canada, 29 August 2013; IEEE: Manhattan, NY, USA, 2013; pp. 469–472. DOI: 10.1109/EIC.2013.6554290
- Jankovic J.; Lukic J.; Kolarski D.; Veljović D.; Radovanović Ž.; Dimitrijević S. Isotherm, Thermodynamic and Kinetic Studies of Elemental Sulfur Removal from Mineral Insulating Oils Using Highly Selective Adsorbent. Materials. 2023; 16 (9) 3522. https://doi.org/10.3390/ma16093522
- Jankovic, J.; Lukic, J.; Planojevic, J.; Kolarski, D.; Janackovic, DJ. Application of Highly Selective Adsorbent in the Removal of Elemental Sulfur and Other Corrosive Sulfur Compounds From Mineral Insulating Oils. IEEE Trans. Dielectr. Electr. Insul. 2022, 29, 54–61. DOI: 10.1109/TDEI.2022.3148479
- International Electrotechnical Commission. Insulating liquids-test method for detection of potentially corrosive sulphur in used and unused insulating oil, IEC 62535-2008.
- Deutsches Institut für Normung. Testing of insulating oils, Detection of corrosive sulfur, silver strip test, Standard 51353, 1985
- ASTM international. Standard Test Method for Corrosive Sulfur in Electrical Insulating Liquids, ASTM D1275-15, ASTM, 2015
- Lukic, J.; Jankovic, J.; Planojevic, J.; Foata, M.; Zieglschmid, C.; Castano, V.; Briotto, A. Silver Sulphide in OLTCs—Root Causes and Proactive Mitigation Strategies. In Proceedings of the TechCon, Aus-NZ, Sydney, Australia, 4–5 April 2019.
- L. Lewand, The role of corrosive sulfur in transformers and transformer oil (2002). Doble Engineering Company, USA. https://www.doble.com/wp-content/uploads/2002_3B.pdf (accessed, February 2025).
- Foata, M.; Lindl, K.H.; Da Costa, M.; Lukic, J.; Jankovic, J.; Mihajlovic, D. Risk Assessment and Mitigation of Corrosive Sulphur Other than DBDS. In Proceedings of the Cigre Brasil X Workspot, Foz do Iguaçu, Brazil, 27–30 November 2022.
- Lewand L, 2002, ‘’The role of corrosive sulfur in transformers and transformer oil’’, In Proceedings of the 69th Annual International Doble Client Conference, Boston, MA, USA, pp 7–12
- IEC 62697 – Part 1: Test method for quantitative determination of dibenzyldisulfide (DBDS), 2012.
- IEC TR 62697 – Part 2: Test method for quantitative determination of total corrosive sulfur (TCS), 2018.
- IEC TR 62697 – Part 3: Test method for quantitative determination of elemental sulfur, 2018.
- CIGRE Brošura 625 – COPPER SULPHIDE LONG TERM MITIGATION AND RISK ASSESSMENT