近区故障开断下真空断路器弧后鞘层发展过程仿真分析

Simulation on the Development Process of Post Arc Sheath under Short-Line Fault Breaking for Vacuum Circuit Breaker

以真空断路器弧后鞘层发展为研究对象,引入等离子体流体力学方程,求解电子、离子密度和平均电子能量的漂移扩散方程和耦合电场的泊松方程。并对真空断路器开断1.0-20.0 km近区故障下弧后鞘层发展时间和弧后阴极电场强度进行仿真分析。仿真结果表明:鞘层发展时间越短,RRRV越小,越有利于成功开断。开断短距离近区故障时,鞘层发展时间相对较长,弧后阴极电场强度大,不利于弧后介质恢复;在开断故障点距离3.0 km时,弧后阴极电场强度达到最大值;在开断故障点距离20.0 km时,弧后阴极电场强度最大值降低了70.5%,鞘层发展时间减少了34.5%,发生击穿几率减小,开断成功率增高。

The development of the post-arc sheath of the vacuum circuit breaker is studied, and the arc plasma hydrodynamics equation is introduced to solve the drift-diffusion equation of electron, ion density and average electron energy and the Poisson equation of the coupled electric field. And the post arc sheath development time and cathode field intensity are analyzed from 1.0 to 20.0 km short-line fault breaking of the vacuum circuit breaker.The simulation results show that the shorter the sheath development time, the smaller RRRV, which is more conducive to successful breaking. In case of short-range fault, the sheath develops for a long time, and the electric field intensity of the post arc cathode is large, which is not conducive to post arc dielectric recovery. Under 3.0 km shortline fault breaking condition, the post arc cathode electric field intensity reaches the maximum. However, under 20.0 km short-line fault breaking condition, the maximum electric field intensity of the post arc cathode is reduced by 70.5%, the sheath development time is reduced by 34.5%, the probability of breakdown decreases, and the success rate of breaking increases.