Research on UHF Wave of Partial Discharge Leakage of Oil-Impregnated Paper Bushing of Power Transformers

The main function of the transformer bushing is to support and connect the transformer lead-out line. In recent years, bushing faults have occurred frequently but there is not good online monitoring method for bushing. The ultra-high frequency (UHF) detection method has the characteristics of strong anti-interference ability and no influence on equipment operation while achieving non-contact measurement. This paper has studied the propagation characteristics of two different UHF electromagnetic waves generated by partial discharge inside the oil impregnated paper (OIP) by simulations of finite element analysis. The attenuation of TEM mode is small, and higher modes below its cutoff frequency is exponentially attenuated. The electromagnetic wave leakage path generated by partial discharge inside the bushing is mainly in the OIP and the oil channels on both sides and the variation trend of the Poynting vector is the same. The externally received field strength spectrum shows that the signal strength is relatively high in the range of 1-2 GHz, considering the equipment used in the actual situation, such as amplifiers it provides a reference for subsequent experiments.