Ultrasonic propagation characteristics of partial discharge in transformer with complex structure

Ultrasonic detection, with its high sensitivity to partial discharge signals and precise localization capabilities, has become an essential tool for transformer condition monitoring and fault diagnosis. Due to the complexity of transformer structures, particularly the reflection, refraction, and scattering phenomena of ultrasound at media interfaces, the propagation characteristics in multimedia remain insufficiently defined. In this study, a transformer simulation model with core windings was developed to investigate the ultrasonic propagation paths within the transformer. The propagation process of ultrasonic waves through multimedia, including transformer oil, windings, and the core, was simulated to reveal the propagation characteristics of ultrasonic waves from the partial discharge source to the observation point. By analyzing the correlation between the initial peak amplitude and arrival time of the received ultrasonic signals, the propagation path was inferred. The results show that the ultrasonic propagation of partial discharge within the transformer is influenced by its complex structure, with two distinct propagation paths: one is direct penetration and the other involves reflection from the tank wall. The attenuation characteristics and arrival times of these two paths differ based on the properties of the propagation media and the distance traveled.