Oil-immersed Power transformers are considered to be one of the most essential parts of the electrical system and partial discharges (PD) are one of the dangerous problems that face transformer insulation. PD is localized dielectric breakdown of an insulation degradation or defect in an oil power transformer. Ultra-high frequency (UHF) detection technique can be utilized in PD detection inside oil-filled power transformers, by capturing the electromagnetic waves generated by PD using an antenna. This research presents a design for a compact double layer printed UHF antenna to detect and discriminate various types of PD activity in a power transformer. PD activity in the transformer has been proposed in this paper by using four different artificial insulation defects, metal protrusion defect in air medium, metal protrusion defect in an oil medium, surface discharge defect, and oil-paper void defect. The presented design guarantees a small-size wideband antenna for detection. The designed antenna has small/simple size and ultra-wide frequency passband from 1.4 to 1.85 GHz, 2.2 to 2.65 GHz, and 3.2 to 3.4 GHz. The normalized power frequency spectra of the captured UHF-PD signals of the four defective models showed that every PD type has its signature, and this could help in the discrimination among different types on site.

油浸式电力变压器被认为是电气系统中最重要的部分之一，局部放电 (PD) 是变压器绝缘面临的危险问题之一。PD 是油电变压器中绝缘退化或缺陷的局部介电击穿。通过使用天线捕获局部放电产生的电磁波，可以将超高频 (UHF) 检测技术用于充油电力变压器内部的局部放电检测。本研究提出了一种紧凑型双层印刷 UHF 天线的设计，用于检测和区分电力变压器中各种类型的 PD 活动。本文通过使用四种不同的人工绝缘缺陷，空气介质中的金属突出缺陷，油介质中的金属突出缺陷，提出了变压器中的局部放电活动，表面放电缺陷和油纸空洞缺陷。所提出的设计保证了用于检测的小尺寸宽带天线。设计的天线具有小/简单的尺寸和1.4至1.85 GHz、2.2至2.65 GHz和3.2至3.4 GHz的超宽频率通带。四个缺陷模型捕获的 UHF-PD 信号的归一化功率频谱表明，每种 PD 类型都有其特征，这有助于现场区分不同类型。