Influence of UHF Filters on Partial-Discharge Measurement in Gas-Insulated Switchgear

The wideband UHF partial-discharge (PD) measurement method is widely used in gas-insulated switchgear (GIS) monitoring solutions. There are several sources of interference within the usable frequency band of this method, such as radar, mobile networks and external discharges. As a result, detection of internal faults with low PD signal strength is not always feasible in a noisy substation environment. The use of UHF filters to selectively filter out interfering signals can improve the identification of PD signals from internal faults, thereby improving the performance and reliability of the PD monitoring system. This research evaluates the effect of different filter designs on mitigating external interference on PD measurements. Data from a laboratory-based setup as well as initial field tests is shown and supports the practical feasibility of implementing UHF filters in GIS PD monitoring systems.