Analyzing the temperature and frequency dependence of eddy currents in transformer windings

• Published in: International journal of electrical power & energy systems Vol. 159; p. 110053
• Main Authors: Badri, José Antonio, Riba, Jordi-Roger, Garcia, Antoni, Trujillo, Santi, Marzàbal, Albert
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.08.2024; Elsevier
• Subjects: Ac inductance; Ac resistance; Eddy currents; Finite elements method; High-frequency; Inductor; Proximity effect; Skin effect; Temperature; Transformer; Winding; Winding; Finite elements method; Temperature; Ac resistance; Transformer; Ac inductance; Proximity effect; Inductor; Skin effect; Eddy currents; High-frequency
• ISSN: 0142-0615; 1879-3517
• DOI: 10.1016/j.ijepes.2024.110053

•We study the effect of skin and proximity effects on the ac impedance of windings.•The effect of temperature and frequency in transformer windings is studied.•We propose an analytical method to separate skin and proximity contributions.•Experimental results and FEA simulations are used to validate the proposed method.•Presented results are based on a single-phase transformer. Eddy current effects, which include skin and proximity effects, are usually associated only with frequency, but they are also affected by temperature. This paper analyzes the effect of both, temperature and frequency on skin and proximity effects in transformer windings. When analyzing transformer windings, despite the existence of powerful finite element analysis (FEA) modules, they return the total contribution of eddy current effects and do not separate the contributions of skin and proximity effects. This paper proposes an analytical method to determine the contribution of both effects to the AC winding resistance and leakage inductance based on the orthogonality of the skin and proximity effects. This method is based on the exact solution of the skin effect for an isolated round conductor combined with Dowell's solution of the proximity effect. Presented experimental results and FEA simulations based on a single-phase transformer have determined the accuracy of the proposed method, which allows accurate prediction of the temperature and frequency behavior of the winding resistance and leakage inductance.