低电压上升率条件下正极性不连续先导发展特性

The Development Characteristics of the Discontinuous Leader Under the Positive Switching Impulse with Low Rate of Voltage Rising

不连续先导发展是正极性棒-板长空气间隙在施加低电压上升率冲击电压下最主要的放电过程,对研究特高压大尺度间隙外绝缘特性有重要的指导意义。基于CMOS高速摄相机,通过搭建棒-板长间隙放电综合观测平台,开展施加不同操作冲击电压的放电试验,获得清晰不连续的先导发展过程图谱以及先导电流、注入电荷、先导通道单位长度电荷等特征参数的变化趋势。进一步根据试验结果分析得到低电压上升率电压作用下的不连续先导发展具有两种不同的规律。最后,本文采用热力学方程,结合试验结果,对不连续先导发展停滞阶段的通道温度变化进行数值计算。结果表明,在先导停滞发展阶段的数百微秒时间尺度内,先导通道温度仍然大于1 500K,后续先导仍能在原有先导通道上继续发展。

Discontinuous leader development is the main discharge process under the application of the switching impulse voltage with the low rate of voltage rising,which is of great significance to study the external insulation characteristics of ultra high voltage(UHV)large scale air gap.Based on the CMOS high-speed camera,discharge tests with different operating impulse voltages were carried out by constructing a comprehensive observation platform of rod-plate long gap discharge,and a clear discontinuous leader development process picture was captured.Moreover,the trend of characteristic parameters was obtained,such as the leader current,injection charge and leader channel unit length charge.Further analysis based on the experimental results shows that the discontinuous leader development under the action of the impulse voltage with low rate of voltage rising has two different laws.Finally,combined with the test results,the discontinuous leader development stagnation stage of the channel temperature changes was calculated by the thermodynamic equation.The results show that the leader channel temperature is still greater than 1 500K in the hundreds of microsecond time scales of the leader stagnation stage,and the subsequent leader can continue to develop on the original leader channel.