Analysis of Electromagnetic Wave Characteristics of PD in Transformer

Ultra-high frequency (UHF) technology is a partial discharge (PD) test technology based on spatial electromagnetic field coupling. It can detect the partial discharge of equipment by detecting the electromagnetic wave signal radiated by PD. It has strong anti-interference ability and high detection sensitivity. Due to the complex internal structure of the transformer, various metal structures may affect the propagation of radiated electromagnetic waves. Therefore, it was necessary to investigated the propagation law of electromagnetic waves inside the transformer. In this article, a simplified model of transformer's internal structure was established. The Gaussian current source was used to simulate the PD source. Moreover, the finite difference time domain (FDTD) method was used to simulate the propagation characteristics of the ultra-high frequency electromagnetic wave inside the transformer. The results showed that the electromagnetic wave was seriously distorted during the propagation of the iron core, the high and low voltage windings, and the signal amplitude attenuation was serious. Increasing the amplitude of the pulse current, the peak value of the radiation length increased. And it still had the same attenuation law after passing through the obstacle.