Design of UHF-SHF sensor for the detection of GIS partial discharge

Abstract

UHF is one of the effective methods which could detect partial discharge in GIS. However, more and more GIS have insulator of metal enclosed structure which leads UHF electromagnetic wave caused by partial discharge could not pass through the insulator. Fortunately, there are little slits between the metal band and the GIS shell which maybe lets higher frequency electromagnetic wave pass. It is possible to detect the partial discharge for GIS with metal enclosed insulator structure by higher frequency. In this paper, we measured the GIS equipment in the laboratory, set up the 1:1 model of GIS equipment based on the measured data. By the simulation software, we simulated the GIS partial discharge by giving a Gaussian pulse signal which is similar to the partial discharge, got the electromagnetic wave spectrum which can spread through the slits between the metal band and the GIS shell. On the basis of the data of the electromagnetic wave spectrum which can be detected, we designed an antenna which could be used for the detection of GIS with metal enclosed insulator structure. With usage of HFSS electromagnetic simulation software, we built up models of two kinds of sensors and repeatedly changed the size of the antenna to the optimal structure according to the simulation optimization data. At last, we got the standing wave ratio direction, radiation pattern, and 3D polar plot of the two sensors. Considering factors such as structural features and portable use, we compared the two kinds of antenna performance difference. The results show that the electromagnetic wave spectrum which can be detected of GIS partial discharge is 0.5–4 GHz, and in this band, the micro-strip antenna is more suitable than equiangular spiral antenna in the detection of partial discharge in GIS.