New Design of UHF Microstrip Patch Antenna for Partial Discharge Detection on Power Transformer

Partial discharge (PD) activity in high-voltage power equipment is a warning sign of insulation degradation that subsequently leads to the aging and breakdown of the power equipment. For the reliable and safe operation of high voltage power equipment, a PD diagnostic technique needs to be performed to assess and monitor closely the insulation condition. This paper presents a new type of UHF microstrip patch antenna with ultra-wideband frequency that can assist the UHF PD monitoring system to detect PD on high voltage equipment such as power transformers. This antenna was designed and simulated using CST Microwave Studio software. After design and simulation, the antenna was fabricated on a printed circuit board with FR4-epoxy substrate having a thickness of 1.6mm and dielectric permittivity of 4.4. The radiating patch and ground plane of this antenna are made of copper whose thickness is 0.035. The designed microstrip patch antenna was implemented to detect partial discharge on the transformer tank model. Based on the measurement results of the antenna characteristic parameters by using the Vector Network Analyzer, it is seen that the designed antenna has an operating frequency range of 1.2GHz-4.5GHz, and a bandwidth of 3.3GHz. Based on PD measurement results, the new design of the microstrip patch antenna has a high sensitivity in detecting the PD signals caused by insulation defects inside the transformer tank. The ultra-wideband frequency response of this antenna makes it a suitable and promising sensor for PD detection and PD recognition on high voltage equipment such as power transformers.