Oil-paper Insulated Power Transformer PD Highly Sensitive Monopole RF Sensing Technology

Addressing the challenges associated with the application of built-in antenna sensors in operational transformers, such as limited gain, and the limited capability of external antenna sensors to detect internal PD signals in transformers, which suffer from low sensitivity and susceptibility to external environmental interference, this paper proposes the design and optimization research of a miniaturized, high-gain monopole ultra-high frequency antenna sensor. This research employs methods such as miniaturization, hollowing out processing, and altering the structure of the monopole grounding plate. Through simulation studies, the effects of transformer insulating oil and insulating gas on antenna performance were investigated. The simulation results show that the volume of the antenna is only 140.4 mm×72 mm×0.4 mm. In the 0.3 GHz to 3 GHz frequency band, the antenna's standing wave ratio is generally less than 5. At three center frequencies of 1 GHz, 1.5 GHz, and 2 GHz, the lowest gain is +1.2, the highest gain can reach +2.71, and the average maximum gain can achieve + 2.0. Additionally, the antenna exhibits good radiation directivity and symmetry, meeting the current performance requirements of PD UHF sensors in oil-paper insulated power transformers.