Comparative Analysis of Partial Discharge Detection Features Using a UHF Antenna and Conventional HFCT Sensor

Abstract

This article presents a design of ultra-high frequency (UHF), ultra-wide band (UWB) antenna used for partial discharge (PD) detection on high voltage and medium voltage power system equipment. The proposed UHF antenna has a working frequency band of 1.2GHz-4.5GHz, covering a total bandwidth of 3.3GHz with a return loss less than -10dB in the entire antenna’s operating frequency. The computer simulation technology (CST) Microwave Studio software was used to design, simulate and optimize the proposed antenna. Upon simulation and optimization process, the antenna prototype was fabricated on the FR-4 substrate of 1.6 mm thickness and dielectric permittivity of 4.4. This antenna has a compact size of 100mm x100mm.The radiating patch and the ground plane of this antenna are made of annealed copper whose thickness is 0.035mm. The simulations and measurement results for the proposed antenna are in a good agreement, and the return loss of this antenna is less than -10dB with voltage standing wave ratio, VSWR, < 2 within the frequency range of interest. The proposed antenna performance in PD sensing is compared with a commercial high-frequency current transformer, HFCT. To validate the sensitivity performance of the designed antenna, experimental PD measurements were carried out by using an epoxy slab inserted between two parallel plates electrode model, in order to generate surface discharge on the insulator, and using a needle-plate electrode configuration to generate corona discharge in transformer oil. Based on PD measurement results, it was shown that the designed antenna has a high sensitivity, which make it a suitable candidate for UHF partial discharge monitoring on high voltage and medium voltage power assets.