Development of Printed Rectangular Microstrip Patch Antenna as UHF Sensor for Partial Discharge Detection in Power Transformers

Partial Discharge (PD) activity in high voltage (HV) and medium voltage (MV) asset is an alarming sign of its insulation deterioration. Ultra-high frequency (UHF) technique, commonly known as the unconventional method, has been widely applied for monitoring the insulation condition of HV and MV apparatuses such as transformers, gas-insulated switchgears (GIS), rotating machines, etc. This UHF method is widely used due to its anti-interference capability, especially for online PD monitoring where electromagnetic interferences such as noise from telecommunication and corona can significantly be mitigated. UHF sensors (antennas) play an integral role in UHF PD monitoring. Many researches on the UHF antennas designs for PD detection on HV or MV power apparatuses have been previously carried out in the literature. However, some UHF sensors developed so far still experience insufficient bandwidth gain, which in turn may result in low sensitivity to PD-induced electromagnetic signals, especially in online PD detection. A new type of UHF antenna called printed rectangular microstrip patch antenna (RMPA) is presented in this paper. This UHF antenna was designed, simulated, and optimized using the HFSS software. The proposed RMPA has a compact size, wide bandwidth and low return loss below −10dB. Upon fabrication of the antenna prototype, the vector network analyzer was used to test the antenna’s performance. In addition, to validate the sensitivity performance of the designed antenna, this antenna was implemented, through laboratory experiments, to capture and measure PD signals emitted by artificial insulation defects in oil insulation. The PD measurement results confirmed that this antenna is suitable for PD monitoring on HV or MV power assets such as oil-insulated transformers.