Numerical Calculation of Direct Current Breakdown Voltage for Complex Short Air Gaps under Varying Altitudes

Abstract

With the increasing construction of ultra-high voltage direct current transmission in high-altitude environments, it becomes crucial to explore the impact of altitude on the short-gap discharge characteristics. To this end, this study proposes a finite element simulation and calculation method for the direct current (DC) breakdown voltage of actual complex short-gap structure under varying altitudes based on the Townsend criterion and the streamer criterion. The method is verified by combining the discharge experiments in Beijing, Qinghai, and Tibet. The results demonstrate that this method can effectively calculate the DC breakdown voltage of gaps between damping capacitors with a relative error range of -3.64% to 0.2%. The research results provide new insights for insulation evaluation of short-gap structures under varying altitudes.