基于改进型直流真空断路器弧后暂态仿真及介质恢复特性分析

Post-Arc Transient Simulation and Dielectric Recovery Analysis Based on Improved DC Vacuum Circuit Breaker

应用于大电流、高di/dt分断环境的直流真空断路器,以绝缘恢复为主要特征的弧后暂态过程直接影响其分断特性。在鞘层发展过程中,弧后阴极表面电场强度及功率密度是引起电弧重燃的两种因素,为探究熄弧后真空断路器恢复电压变化规律,该文首先从提升弧后介质恢复能力的角度出发,在燃弧电流峰值约23kA、熄弧电流变化率约300A/μs的等级上先后开展不同试验方案,并在连续过渡型鞘层数学建模基础上做出一定修缮,引入触头开距动态变化过程和电弧有效直径变量,依据改进后电弧模型指导换流回路参数设计。最后将PSCAD/EMTDC电磁暂态仿真与分断试验现象进行等价对比分析,显示试验过程中真空断路器弧后电弧重燃趋势与仿真结果较为贴合,且通过仿真结果可判定重击穿的类别,从而验证了改进后真空断路器弧后电磁暂态建模的精确性。

For DC vacuum circuit breakers used in high current and high di/dt breaking environments,the post-arc transient process with insulation recovery as the main feature directly affects their breaking characteristics.During the development of the sheath,the electric field strength and power density of the cathode surface after the end of arcing are the two factors that cause arc reignition.From the perspective of improving the recovery capability of the medium after the arcing,different test schemes were carried out at the peak arc current of about 23kA and the rate of the arc-extinguishing current of about 300A/μs.Moreover,based on continuous transitional sheath modeling,the variables such as contact opening dynamic process and the effective diameter of the arc are introduced.The design of commutation circuit parameters is guided based on the improved arc model.Finally,the equivalent analysis of PSCAD/EMTDC electromagnetic transient simulation and test is carried out.It is shown that the arc re-ignition trend of the vacuum circuit breaker after the arcing in the test is consistent with the simulation results,and the type of re-strike can be determined through the simulation results.Therefore,the improved post-arc electromagnetic transient modeling of vacuum circuit breaker is verified.