基于多断口腔室结构的多重雷击灭弧机理仿真分析

Simulation Analysis of Arc Extinction Mechanism of Multi-Break Parallel Gap Based on Multiple Lightning Strikes

针对多重雷击引起的工频建弧防护问题,基于磁流体动力学理论(MHD),利用COMSOL Multiphysics软件建立了多断口腔室结构中的多重雷击击穿的二维模型,分析了该腔室中工频电弧的运动特性及该装置的灭弧性能。结果表明,多断口腔室结构通过产生灭弧气流纵吹熄灭工频电弧。同时,根据回击间隔时间不同,应考虑灭弧腔室内物理状态对灭弧性能的影响,即间隔时间较短时,灭弧通道内形成高温高压类真空区域,使弧柱电导率快速下降,工频焦耳热源无法维持电弧稳定燃烧;随着间隔时间的延长,灭弧腔室内形成空气回流,回流具有切断焦耳热源与加速散热效率的作用,当间隔时间达60ms时,各次回击时刻均能产生强大的灭弧气流,实现在多重雷击的叠加作用下一对一多次可靠地截断电弧。

Aiming at the protection problem of power frequency arc construction caused by multiple lightning strikes,based on the magneto hydrodynamic theory(MHD),the two-dimensional model of multiple lightning breakdowns in multi-break chamber structure was established using COMSOL Multiphysics software.The motion characteristics of power frequency arc and the arc extinguishing performance of the chamber were analyzed.The simulation results show that the multi-break chamber structure extinguishes the power frequency arc longitudinally by generating an arc extinguishing air flow.According to the difference of the return interval,the effect of the state of the arc extinguishing chamber on the arc extinguishing performance should be considered.When the interval time is shorter,the formation of a high-temperature and high-pressure vacuum area causes the arc column conductivity to decrease rapidly,and the power frequency Joule heat source cannot maintain the stable combustion of the arc.As the interval time increases,air recirculation is formed in the arc extinguishing chamber,which has the effect of cutting off the Joule heat source and accelerating the heat dissipation efficiency.When the interval time reaches 60 ms,each reflux moment can generate an arc extinguishing air flow.Under the superimposition of multiple lightning strikes,the arc can be cut off one to one and many times reliably.