As the key equipment of flexible DC transmission, the operational reliability of DC high speed switch (HSS) is of great significance. However, surface charge gradually accumulated on the insulators under DC voltage when the HSS double-break is in the opening position, which further leading to the electric field distortion and even discharge. In this paper, a 3D finite simulation model was established based on the actual operating conditions of HSS. Besides, the worst operation condition of HSS that under the opening position was calculated and analyzed. Then the multi-coupled surface charge accumulated model which considered charge drift and diffusion was established based on the obtained most severe condition. Moreover, the electric field distribution and charge distribution of insulators in HSS breaker chamber was computed. The surface charge accumulation characteristics of insulators and its effect on electric field distribution was analyzed. The results show that the charge accumulated on the nozzle is much greater than the wall inside chamber. The obtained results provide a guidance for the design of HSS double-break.
 

high speed switch,DC,gas-solid surface,surface charge