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Vol. 36 No. 192: Journal of Science and Technology - Smart Systems and Devices 2026
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Research article
How to Cite
Tran, V. L., Ho, N. T., Ho, V. T., Doan, T. B., Le, D. D., & Nguyen, K. A. (2026). Thermal Effects of Harmonics on Distribution Transformers: A Coupled Electromagnetic–Thermal Finite-Element-Based Approach. Smart Systems and Devices, 36(192). https://jst.vn/index.php/ssad/article/view/1216

Thermal Effects of Harmonics on Distribution Transformers: A Coupled Electromagnetic–Thermal Finite-Element-Based Approach

Van Loi Tran1, Nguyen Thao Ho1, Van Trung Ho1, Thanh Bao Doan2, Dinh Duong Le1, Kim Anh Nguyen1,
1 Faculty of Electrical Engineering, The University of Danang - University of Science and Technology
2 Faculty of Engineering and Technology, Quy Nhon University

Main Article Content

Abstract

The growing demand for electrical energy, together with increasingly complex operating conditions caused by nonlinear loads and the widespread integration of renewable energy sources, has led to increased harmonic distortion in power systems. As critical assets in distribution networks, transformers are particularly vulnerable to harmonic-induced losses and thermal stress, which can accelerate insulation aging and reduce service life. This study investigates the thermal effects of harmonics on a medium-voltage distribution transformer using a coupled electromagnetic–thermal approach based on the finite element method. In the proposed workflow, ANSYS Maxwell is used to compute electromagnetic quantities and harmonic-dependent losses, and these losses are then used as inputs to an equivalent electro-thermal model to predict top-oil and winding hot-spot temperatures. The electromagnetic model is validated under no-load and short-circuit conditions, and simulations are conducted for linear and nonlinear loads at 50%, 100%, and 125% of rated load. The hybrid thermal prediction results show good agreement with detailed ANSYS Mechanical simulations, with a deviation of approximately 3% in the linear-load case and 0.016% in the nonlinear-load case. The results show that harmonic loading significantly increases load-related losses and hot-spot temperature, while also revealing a non-uniform temperature distribution that enables hot-spot localization. The obtained spatial hot-spot information supports insulation loss-of-life assessment and provides practical guidance for design improvement, sensor placement, periodic inspection/testing, spare-part planning, and condition-based maintenance under harmonic operating conditions.

Keywords

current harmonics, electromagnetic-thermal modeling, finite element method, medium-voltage transformer, thermal behavior

Article Details

Creative Commons License

This work is licensed under a Creative Commons Attribution 4.0 International License.

Author Biography

Dr. Engr. Kim Anh Nguyen, Faculty of Electrical Engineering, The University of Danang - University of Science and Technology

Kim-Anh Nguyen is currently a lecturer at TFaculty of Electrical Engineering, The University of Danang - University of Science and Technology, Danang, Vietnam. He served as the Head of the Automation Division in the Faculty of Electrical Engineering from 2016 to 2020. He received his Engineer’s degree in Electrical Engineering from the University of Science and Technology in 2004, an M.Eng. degree in Control Engineering and Automation from the University of Danang in 2009, and a Ph.D. in Systems Optimization and Dependability from Troyes University of Technology, France, in 2015. His current research interests include stochastic modeling of system deterioration, diagnosis, prognosis and health management techniques, maintenance decision-making, power electronics, power quality, IoT, embedded system, and control systems. You can contact him via email: nkanh@dut.udn.vn.

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