Study on vibration characteristics of converter transformers under inrush current

This research employs a three-dimensional finite element framework incorporating bidirectional electromagnetic-structural interaction to analyze the vibrational response of a 500 kV converter transformer subjected to inrush current conditions. The vibration of the core and windings are systematically analyzed under different inrush current conditions. Temporal and spectral characteristics of vibration signatures are systematically examined to quantify the influences of switching phase angles and remnant magnetic flux. Simulations under rated load conditions validate the model's accuracy, showing less than 4% error compared to nameplate values. The results indicate that the closing angle significantly influences vibration amplitude: at a 0° closing angle, the peak radial acceleration of the winding reaches 110.52 m/s², with dominant frequency bands at 150-400 Hz for the core and 475 Hz for the winding. In contrast, residual flux considerably increases the inrush current magnitude and distortion but has a limited impact on vibration, resulting in a maximum winding acceleration of 50.38 m/s² at 0.8 pu. The findings provide theoretical and numerical support for vibration suppression and condition monitoring in converter transformers.