A GIS partial discharge（PD） detection system with ultrasonic and electrical combination is designed based on virtual instrument.Simultaneous multi-channel detections are applied to the ultra-high-frequency signals

high-frequency current signals and ultrasonic signals generated by GIS partial discharges via data acquisition modules with different sampling rates.The detection system based on virtual instrument platform can continuously capture and store PD pulse signals

and calculate PD pulse phase information.The separation of multi-source PD and distinction of PD type are achieved by using time-frequency analysis and fuzzy clustering.PD source location is carried out by multiple UHF signals and ultrasonic signals or their time difference.Field detections are conducted with the proposed system in several 220 kV and 500 kV GIS substations

and the results verify the effectiveness of the system.