Optimization of UHF Hilbert Antenna for Partial Discharge Detection of Transformers

Partial discharge (PD) online monitoring is an effective tool of inspecting insulation defects and identifying potential faults in power transformers. Ultra-high-frequency (UHF) approaches have caught increasing attention recently and been considered as a promising technology for online monitoring PD signals. The size of a UHF sensor for PD online monitoring of transformer is a critical factor for practical installation inside transformer. This communication presents a compact fourth order UHF Hilbert fractal antenna with desired performance and suitable size for easy installation. Actual PD experiments were carried out for four typical artificial insulation defect models while the antenna was used for PD measurements. The experimental results show that the proposed Hilbert fractal antenna is suitable and effective for UHF online monitoring of PDs in transformers.