Development of UHF Sensors for Partial Discharge Detection in Power Transformer

Partial discharge (PD) is a symptom of insulation defect or degradation in high-voltage power equipment. To detect the occurrence of PDs inside oil-filled power transformers, the ultra-high frequency (UHF) detection method is one that can be applied. To date, the sensors, as the most important part in the UHF method, have not been adequately addressed in terms of sensitivity and accuracy. This paper presents a novel UHF sensor called microstrip-fed planar elliptical monopole antenna. This antenna has a simple structure and ultra-wide frequency band. It is designed and simulated using CST software for parametric optimization. Following fabrication, its performance verification is carried out using an experimental test setup for PD source. In addition, comparison is made between various UHF antennas regarding their advantage and limitation. The results show that the new UHF antenna is suitable for PD detection in oil-insulated transformer and its ultra-wide bandwidth frequency response can be a useful means for PD recognition.