自能式多断口结构对电弧抑制的仿真优化

Study on Mechanism of Self-energy Arc Suppression Based on Multi-break Structure

由于雷击跳闸的高发性,降低绝缘子旁路空气间隙建弧率有重要研究意义。多断口灭弧防雷间隙是一种带有灭弧功能的并联间隙,能有效降低绝缘子旁路的建弧率。基于MHD磁流体理论,利用COMSOL Multiphysics多物理场仿真平台建立了多断口灭弧结构的2维几何模型,通过分析电弧在该结构中的物理特性,详细解释了该结构熄灭雷电弧并抑制电弧发展的原理。根据仿真结果显示,半封闭空间的断口结构强力压缩电弧产生了瞬时温升,瞬时的温升是产生自膨胀气流的原因,温度变化的速率影响了自膨胀气流的速度大小;工频电弧无法稳定形成是由于雷电脉冲阶段电弧在灭弧结构的断口处定点截断,切断了电弧的焦耳热源;断口结构对建弧难度、熄弧效果有重大影响。

Because of high incidence of lightning-strike caused tripping, it is of great significance to reduce arc establishing rate of air gap in insulator bypass. Multi-break arc extinguishing lightning protection gap is a kind of parallel gap with arc extinguishing function, able to effectively reduce the arc establishing rate of insulator bypass. Based on theory of MHD(magnetohydrodynamics) magnetic liquid, and using COMSOL multi-physics simulation platform, a 2-D geometry model of the multi-break arc extinguishing structure was built. By analyzing the physical characteristics of the arc in the structure, the arc extinguishing principle and restraint of arc development were explained. According to simulation results, the semi-closed space of the multi-break structure had strong compression on arc and formed instantaneous temperature rise. The instantaneous temperature rise causes a self-expanding airflow, and velocity of temperature change affects the velocity of self-expanding airflow. Instability of power frequency arc is caused by blocking the arc at the break point of the arc extinguishing structure at lightning pulse stage, cutting off the joule heat source of the arc. The break structure has great influence on difficulty of arc building and effect of arc extinguishing.