Investigation on the propagation characteristic of electromagnetic waves in converter transformers

Ultra-high-frequency (UHF) approaches, when used to detect partial discharge in converter transformers, can avoid the impulse interference generated by converter valve, thus contributing to high sensitivity. The electromagnetic waves (EM-waves) propagation in transformer could be affected by transformer components and other factors. In this paper, a simulation model of converter transformer was built up based on a reasonable simplification of transformer components. And then the EM-waves propagation characteristics in transformer was simulated and studied with Finite Difference Time Domain (FDTD) method. The simulation results explained the propagation characteristics of EM-waves between the core and windings, the attenuation and distortion of EM-waves caused by the core, windings and bushings.