4th International Conference on Electric Power Equipment– Switching Technology (ICEPE-2017)

385 / 2017-04-24 15:20:03

Dynamic Behaviors of the Streamer Evolution in SF6-N2 Narrow-gap

SF6-N2 gas will be an important insulated medium and wildly applied to the power system for gas-insulated equipment. This paper aims to deeply understand the streamer discharge mechanism in SF6-N2 appeared erratic phenomena while practice operation of the high-voltage apparatus, then help one to better use reasonably the SF6.
The two-dimensional and self-consistent fluid model of the SF6-N2 discharge were established based on the electron and ion continuity equations coupled to Poisson’s equation, and including the model of photo-ionization. For speeding up the enormous calculating convergence and meeting accuracy highly requirement, some simplified technique was also implemented for the intricate computing process. Meanwhile, the flux corrected transport technique (FCT) was employed for treating the particle flux-continuity equations, then the iterative symmetric successive over-relaxation(SOR) method was utilized to numerically solve the coupling Poisson's electric field within the narrow-gap.
Gratifying Results of two-dimensional simulation of cylindrically symmetric streamer in SF6-N2 narrow-gap between parallel-plane electrodes are achieved. We present and discuss the stages about streamer triggering, developing and breakdown processes, so that the discharge channel microcosmic evolution is revealed based on the dynamic behaviors of charged particles during discharge in SF6-N2 narrow-gap model. Simultaneously, the temporal and spatial characteristic distribution of charged particle densities, electric field strength and streamer propagating velocity during the progression of discharges in the SF6-N2 narrow-gap are all discovered, and the fulfilling results show that whole discharge course has three visible phases. In addition, by comparing the results of simulation with and without photo-ionization process, the facts are also proved that the photo-ionization plays an key role during the streamer propagation phase, which both accelerates the velocity of the streamer propagation and products much more actively charged particles, so that the photo-ionization may aggravate breakdown quickly in the SF6-N2 narrow-gap.