Simulation Study on Fault Signals of Ultrasonic and UHF Electromagnetic Waves in Converter Riser Based on Finite Element Method

The safe and reliable operation of high-voltage converter transformers is essential for the stability of high-voltage power grids. In this study, we focus on the bushing insulator, a common fault location in high-voltage converter transformers. Using the COMSOL finite element simulation software, we establish a model for the bushing insulator and create localized partial discharge fault points based on actual sources of partial discharge. We conduct ultrasonic and electromagnetic simulations to assess the vulnerability of the bushing insulator. The simulation results indicate distinct differences in the average sound pressure and electric field intensity generated by partial discharges. The internal average sound pressure and electric field intensity are much higher than those outside the bushing insulator. Both ultrasonic and electromagnetic waves experience significant attenuation after passing through the external wall of the bushing insulator, with ultrasonic waves experiencing much greater attenuation than electromagnetic waves. Leakage of ultrasonic waves is evident at the lower and upper sealing points of the casing and the observation window, while electromagnetic wave leakage primarily occurs at the observation window and, to a lesser extent, at the lower sealing point of the casing. This study provides theoretical support for the selection and arrangement of sensors for real-world bushing insulators.