The Transition Mechanism of Surface Charge Accumulation Dominating Way in DC GIS/GIL

A surface charge accumulation simulation model was constructed to study the transition mechanism of surface charge accumulation dominating way, in which three ways of surface charge accumulation, i.e. electric conduction within gas (including generation, recombination, drift and diffusion process of charge carriers), electric conduction through insulator volume and electric conduction along insulator surface, were taken into consideration. The results indicated that, the polarity of the surface charge on the insulator varies with the change of ion pair generation rate and volume conductivity, and the dominating way of surface charge accumulation would take a transition between electric conduction within gas and electric conduction through insulator volume in the process. The critical value of ion pair generation rate and volume conductivity were defined respectively to describe the transition process according to the change law of net charge. The critical ion pair generation pairs of the upper and lower surface were different due to the non-uniform distribution of electric field, and the critical volume conductivity was calculated to 5.76×10-18S/m. With the surface conductivity increased, the effect of electric conduction along insulator surface is gradually increased. It can be inferred that when the surface conductivity reaches large enough, the dominant mechanism of charge accumulation will be converted into electric conduction along insulator surface. Our research is helpful to understand surface charge accumulation mechanism and provide suggestions aiming to inhibit surface charge accumulation. © 2019, Electrical Technology Press Co. Ltd. All right reserved.