Motion Characteristics Analysis of DC Arc on Arcing Horn
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摘要:
接地极线路是直流输电系统的重要组成部分,是直流系统不平衡电流和大地回流的入地通道. 接地极线路遭遇雷击时,入地电流会在招弧角间隙形成稳定电弧,由于直流电流不存在周期性过零点,直流电弧很难熄灭,进而破坏线路绝缘,严重威胁直流输电系统安全. 针对接地极线路招弧角处于野外开放空间、电弧运动受多场耦合影响的特点,建立了招弧角电弧磁流体动力学二维仿真模型,研究气流速度、方向以及招弧角结构对直流电弧运动特性的影响. 研究表明:招弧角电极电弧主要受电磁力作用沿电极扩张方向运动,通过吹弧和拉伸,降低电弧温度,提高电弧电压,使电弧更利于熄灭;气流环境对电弧动态特性产生较大影响,同方向风速有利于电弧的吹离和疏导;同等风速下,水平方向气流吹弧效果更显著;电极样式对电弧的拉伸有重要影响,同等间隙距离下,双羊角电极对电弧的拉伸作用比单羊角电极更强;在入地电流持续注入的情况下,电弧易重燃,且难以彻底熄灭.
Abstract:Grounding electrode line is an important part of the DC power transmission system, and it is a channel for the unbalanced current and the grounding current in the DC system. When the grounding electrode line is attacked by lightning, the grounding current will form a stable arc in the gap. Since the DC current has no periodic zero crossing point, the DC arc is difficult to extinguish, which damages the line insulation and seriously threatens the safety of the entire system. As the arcing horn of the grounding electrode line is in an open space, and the arc motion is affected by multi-field coupling, a two-dimensional simulation model of the arc horn based on magnetohydrodynamics is built to study the effects of the airflow velocity, direction and the structure of arcing horn on the DC arc motion. The results show that the arc is mainly driven by electromagnetic force and moves along the electrode. Through the arc blowing and stretching, the temperature is reduced, and the voltage is increased, which are beneficial to extinguishing arc. The airflow has a greater influence on the dynamic characteristics of the arc, and the wind speed in the same direction is beneficial to the blowing and dredging of the arc. At the same wind speed, the normal airflow plays a major role in the arc blowing. Electrode types have an important effect on the stretching of the arc. With the same gap distance, the double-horn electrode has a more significant stretching effect on the arc than the single-horn electrode. When the DC ground current is continuously injected, the arc is easy to reignite and difficult to extinguish completely.
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Key words:
- grounding electrode line /
- arcing horn /
- DC arc /
- magneto hydro dynamics /
- motion characteristics
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表 1 仿真模型几何尺寸
Table 1. Dimensions of simulation model
边界 类别 尺寸/cm AB、DE 电极 25 BC、EF 电极 40 GH、IJ 开放边界 250 GJ、HI 开放边界 250 BE 空气间隙 30 表 2 电弧长度变化
Table 2. Arc lengths at different time points
t/ms 电弧电压/
V电弧长度/
cm电位梯度/
(V·mm−1)20 478 30.9 1.5 40 476 36.3 1.3 60 671 53.9 1.2 80 956 89.0 1.1 100 2957 263.2 1.1 110 5409 505.9 1.1 -
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