Study on the Influence of Harmonics on the Temperature Distribution of Traction Transformers Based on Long-Term Waveform Recording Data

Based on long-term waveform recording data, this study establishes a magneto-thermal-fluid multiphysics coupling simulation model to investigate the impact of harmonics on the internal temperature distribution of traction transformers. By analyzing 24-hour actual recording data from the 27.5 kV bus of a traction substation, the specific characteristics of high-frequency harmonic components were identified, and an electromagnetic loss calculation model considering the time-varying characteristics of harmonics was developed. Simulation results indicate that under harmonic conditions, the hotspot temperature at the interface between the transformer winding and the iron core significantly increases, reaching a maximum of 97.2°C, which is 21.3% higher than under non-harmonic conditions. Additionally, the overall average temperature rises by 17.2%. Lifetime assessment based on the Arrhenius aging model reveals that the hotspot temperature rise considerably shortens the service life of the oil-paper insulation material, with a maximum reduction of 70%. This study provides theoretical foundations and data support for harmonic mitigation, optimal design, and operational maintenance of traction transformers.