Application of a Novel Type of UHF Antenna for Partial Discharge Detection in Power Transformers Oil Insulation

This partial discharge measurement technique has been widely used as a powerful tool to assess the insulation condition of high voltage (HV) and medium voltage (MV) power equipment. UHF partial discharge (PD) detection method which applies UHF sensors has shown the capability to detect, localize and identify potential insulation defects. This paper presents a novel type of UHF microstrip patch antenna with an ultra-wideband frequency that was designed, manufactured, and implemented for PD detection in power transformer oil insulation. The proposed antenna was designed and simulated using the CST Microwave Studio Software. This antenna was printed on FR4 epoxy substrate whose thickness is 1.6mm and whose permittivity is 4.4. The copper material whose thickness is 0.035mm, was used on the radiating patch and ground plane of the antenna. The optimal design of the proposed antenna has a total bandwidth of 3.3GHz, under -10dB. The prototype of this antenna was fabricated and later on measured by using the vector network analyzer (VNA). After antenna fabrication, laboratory experiments were conducted to investigate the antenna's sensitivity performance in detecting PD activity in transformer oil insulation. The PD measurement results obtained by using the proposed antenna in comparison with the HFCT proved that the designed antenna has a high sensitivity to detect EM waves induced by PD activity in oil insulation, which makes it a promising sensor that can be used in the diagnosis of power transformer insulation based on UHF PD measurement technique.