Measurement and analysis of partial discharges in SF6 gas under HVDC

• Electrode systems were fabricated to simulate typical insulation defects in GIS.
• The real-time PD measurement system was developed based on LabVIEW program.
• Discharge inception voltage, discharge magnitude, and pulse count were analyzed.
• Statistical characteristics were extracted from discharge distribution and density function.
• Twelve parameters were useful for defects identification under HVDC.

With the rapid development of high voltage direct current (HVDC) technology and the requirements of smart grids, there is a new challenge of monitoring and diagnosing the insulation performance of related power facilities. This paper dealt with the measurements and analysis of partial discharges in SF6 gas under HVDC in terms of discharge inception voltage (DIV), discharge magnitude and pulse count, as well as the statistical characteristics extracted from discharge distribution and density functions. Five types of electrode systems were fabricated to simulate typical insulation defects in gas-insulated switchgear. All these systems were filled with SF6 gas in ranges from 0.1 to 0.5 MPa. The measurement system was developed based on the real time operating system by LabVIEW. The results revealed that identification of the defects in gas-insulated equipment operated under HVDC can be realized by analyzing the statistical characteristics extracted from the discharge distribution and density functions.