Research on Transformer Flow-thermal Coupling Calculation Considering Harmonic Influence

Grid harmonics generated additional loss in the transformer, which would lead the transformer winding to overheat. The influence of harmonics on the temperature field of transformer was observed by considering harmonic loss in the transformer flow-heat coupling calculation. This paper took the hysteresis loss, eddy current loss and winding harmonic loss under the influence of harmonics into consideration. The transformer loss calculation formula was derived. Therefore, the temperature distribution of transformer under harmonic condition was obtained through flow-thermal coupling calculation. The hot spot temperature was 73.4°C, which was within safe range. The calculation results of the fluid field showed that the asymmetric structure of the transformer lead to the asymmetry of the heat dissipation path of the oil flow, which brought about the asymmetry of the final temperature distribution result. This paper improved the flow-thermal coupling calculation method because of considering harmonic loss, which provided a reference for improving the calculation accuracy in running transformer.