Vibration Model of ±800 kV Converter Transformers Under Varying Load Conditions

Understanding the relationship between current harmonics and vibration is crucial for accurately modeling converter transformer vibrations, particularly under varying load conditions. In this study, vibrations of six converter transformers were monitored during the commissioning of the ±800 kV/8000 MW DC system, from no-load to full-load. A multi-frequency vibration model was established by considering the currents’ interactions and the phase effects. The model demonstrates that the phase relationship between current harmonics is essential for predicting vibrations at specific frequencies and successfully explains the non-monotonic trend observed in the 300 Hz component under increasing load. Analysis further indicates that winding vibration was concentrated in the 100–400 Hz range and exhibited strong load dependence, becoming predominant above 2500 MW. More importantly, whereas the amplitude of these components increased significantly with load, their phase remained stable beyond this load threshold, showing potential for diagnostic applications. In contrast, the 1300 Hz vibration originated primarily from the core and showed a weaker correlation with load variation. These findings provide valuable insights for improving vibration models and advancing fault diagnosis methods for converter transformers.