Experimental study on streamer-leader transition characteristics of sphere-plane gap in valve hall under positive switching impulse voltage

Abstract

Since a large number of spherical shielding balls are adopted in valve hall, investigating discharge characteristics of sphere-plane gap is of great significance for insulation design in HVDC projects. In order to study the discharge physical process of sphere-plane gap, this paper conducts sphere-plane gap experiment with gap distance set to 1.0 m and 1.5 m and electrode diameter set to 0.2 m, 0.3 m and 0.4 m under positive switching impulse voltage. The experimental comparative analysis of the discharge process of streamer-leader transition, and the physical parameters such as leader velocity and the amount of injected charge are calculated. The results show that the streamer to leader transition process is accelerated as the spherical electrode diameter increases. The leader velocity of sphere-plane gap is almost consistent with that of rod-plane gap. And the charge injected into initial streamer is much high than that of rod-plane gap.