Multi-Physics Numerical Research in Oil-Immersed Three-Phase Transformer Under Load Unbalance

Guanxun Diao, Heli Ni, Wenrong Si, Yingjie Gu and Jian Yang ()
Additional contact information
Guanxun Diao: State Grid Shanghai Municipal Electrical Power Company, Shanghai 200122, China
Heli Ni: State Grid Shanghai Municipal Electrical Power Company, Shanghai 200122, China
Wenrong Si: State Grid Shanghai Municipal Electrical Power Company, Shanghai 200122, China
Yingjie Gu: MOE Key Laboratory of Thermo-Fluid Science and Engineering, Xi’an Jiaotong University, Xi’an 710049, China
Jian Yang: MOE Key Laboratory of Thermo-Fluid Science and Engineering, Xi’an Jiaotong University, Xi’an 710049, China

Energies, 2025, vol. 18, issue 5, 1-34

Abstract: Transformers are susceptible to the influences of complex power grid systems, which may induce three-phase unbalance in transformers, thereby threatening their safety and stable operation. To better understand multiphysics interactions within a transformer under a three-phase load unbalance, a coupled multiphysics model is established and validated for an oil-immersed transformer based on the finite element method. The electromagnetic characteristics, conjugate heat transfer, and thermal stress of the transformer under three-phase load unbalance are analyzed, and the impact on the transformer’s relative aging rate is further assessed. The results show that under three-phase load unbalance, winding losses are significantly influenced by the degree of unbalance, while core losses remain almost unaffected. The maximum difference in winding losses between phases can reach 9.6 times, with a total loss increase of approximately 17.31% at a 30% unbalance degree for Case 3. The mutual heating effect between adjacent windings intensifies with the degree of unbalance, leading to higher temperatures in low-loss windings and sustaining high thermal stress and expansion. Severe three-phase unbalance (e.g., 30% unbalance degree in Case 3) can be mitigated by reducing the transformer load rate to 90%, thereby reducing the relative aging rate to about 20% of that under full load and significantly extending the transformer’s insulation life.

Keywords: transformer; three-phase unbalance; multiphysics field; numerical simulation (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2025
References: View references in EconPapers View complete reference list from CitEc
Citations:

Downloads: (external link)
https://www.mdpi.com/1996-1073/18/5/1217/pdf (application/pdf)
https://www.mdpi.com/1996-1073/18/5/1217/ (text/html)

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:gam:jeners:v:18:y:2025:i:5:p:1217-:d:1603752

Access Statistics for this article

Energies is currently edited by Ms. Agatha Cao

More articles in Energies from MDPI
Bibliographic data for series maintained by MDPI Indexing Manager ().