External sensors in partial discharge ultra‐high‐frequency measurements in gas‐insulated substations

SUMMARY Although the ultra‐high‐frequency (UHF) method of detecting partial discharge (PD) in gas insulation substations (GISs) is an interesting research topic because of its remarkable anti‐jamming ability, applying inner UHF sensors to detect PD in operational GISs is a difficult task. The structure of GISs and the characteristics of PD electromagnetic wave transmission and leakage are determined using external antenna sensors to detect PD signals based on the theory of linear antennas. Two decimetric‐wave antennas with different detection bandwidths are made using techniques such as additional impedance, shielding and asymmetrical forms to measure UHF. The UHF external antenna sensor measurement system is able to collect PD signals from the GIS equipment, and its anti‐jamming ability is better than that of the low‐frequency sensor measurement system in the UHF band. Copyright © 2011 John Wiley & Sons, Ltd.