Optimization and Analysis of Leakage Reactance for a Converter Transformer of the Electric Transport System

Dawood K., Kömürgöz Kırış G., Işik F.

Journal of Electrical Engineering and Technology, vol.19, no.1, pp.351-360, 2024 (SCI-Expanded) identifier

  • Publication Type: Article / Article
  • Volume: 19 Issue: 1
  • Publication Date: 2024
  • Doi Number: 10.1007/s42835-023-01516-w
  • Journal Name: Journal of Electrical Engineering and Technology
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Compendex, INSPEC
  • Page Numbers: pp.351-360
  • Keywords: Converter transformer, Electric transport system, Finite element method, Leakage reactance, Transient analysis
  • Istanbul Technical University Affiliated: Yes


Converter transformers are widely used in the electric transport system and it is crucial equipment for the rectifier unit of the transport’s tracking substations. Leakage reactance is a crucial criterion during the development of a converter transformer. Almost all of the analytical methods consider only the axial leakage flux density during the evaluation of the leakage reactance. Radial leakage flux density is neglected in the analytical methods. Neglecting the radial leakage flux density during the computation of the leakage reactance in the two-winding transformers and other power transformers does not significantly affect the results. However, in the case of the converter transformers, radial leakage flux density also needs to be fully considered. In some of the converter transformers; windings, core, insulation material, and other parts of the transformer are so complex that analytical methods are impossible or difficult to implement. Hence, any other method is needed to evaluate the different parameters of the transformer. The optimal selection of leakage reactance is an important parameter during the design of the converter transformer. Numerical computational methods are one of the most commonly used techniques to solve and analyse the complex models of transformers. To accurately compute the leakage reactance of the electric transport system transformer (traction transformer), a transient method is used, which considers the effect of the radial leakage flux density. A prototype converter transformer of the electric transport system has been developed to obtain the experimental results. A transient method results and prototype transformer results show excellent agreement and verify the correctness of the finite element model. The results of the traditional analytical and magnetostatics finite element analysis are also compared with the short-circuit experimental test.