Analysis of Influencing Factors of Self-Sustaining Discharge Along Surface of DC GIL/GIS Spacer

To enhance the stability and reliability of GIS/GIL equipment in high-voltage direct current (HVDC) transmission systems, this study considers the multi-physics coupling conditions experienced by basin-type insulators during actual operation. Surface self-sustaining discharge experiments were conducted under the influence of temperature during the adsorption of metallic contaminants. The effects of voltage polarity and temperature on the inception voltage and flashover voltage of DC surface self-sustaining discharges were analyzed and validated. The results show that the inception voltage decreases with increasing temperature. The positive polarity always exhibits a higher inception voltage than the negative polarity, which aligns with the polarity effect observed in highly non-uniform electric fields. The inception voltage under negative polarity remains relatively stable and shows an approximately monotonic decreasing trend. For flashover voltage, a rapid decline is observed at the initial stage under positive polarity, followed by a gradual stabilization, whereas under negative polarity, the initial decline is slower but accelerates significantly in the later stages.