A Novel Composite Sensor for UHF Partial Discharge and Gas State Measurement in GIS

The gas state of the insulating gas significantly impacts the development and extent of the partial discharge (PD) in gas insulated switchgear (GIS). Correlating these two factors allows for a more comprehensive diagnosis of insulation defects. At present, the ultra-high frequency (UHF) method has been widely used for PD detection in GIS. However, measurements of the insulating gas's state in the field are primarily conducted offline or at gas valves, providing ineffective data for reference. To address this challenge, this paper introduces a novel composite sensor capable of simultaneous UHF and gas state measurements. Building upon the disc-type UHF sensor structure, the composite sensor integrates a gas state sensing unit with the microelectromechanical systems (MEMS) sensor as the core. A robust shielding shell is designed through finite element simulation to ensure the safety of the sensor, with the maximum induced voltage and electric field strength on the sensing unit measuring 0.28V and 414V/m, respectively. The average UHF measurement sensitivity of the composite sensor reaches 13.3mm. In addition, the composite sensor exhibits low errors (±0.2°C, ±3kPa and ±10μL/L), high consistency and repeatability in temperature, pressure and moisture measurement. Finally, the composite sensor has demonstrated its capability to simultaneously and safely detect PD signals and the gas state within GIS.