正极性雷电冲击电压下流注起始时延特性

Streamer Inception Time Delay Characteristics Under Positive Lightning Impulse Voltage

流注起始时延特性,体现冲击电压作用下流注起始的随机特性,是流注起始特性的重要组成部分。研究流注起始时延特性有助于揭示长空气间隙放电机制。基于实验数据,认为有效自由电子形成的统计时延是流注起始时延的主要部分;从有效自由电子形成过程出发,通过理论推导,引入概率密度函数描述流注起始时延;并用大量实验数据进行统计分析。结果表明流注起始时延服从瑞利分布;瑞利分布的均值即为起始时延的均值,其方差即为起始时延的分散性。瑞利分布的特征参数具有明显的物理含义,可以很好地解释流注起始时延的变化规律。在正极性雷电冲击电压作用下,电压变化率在80-240kV/s、棒电极半径在0.5-2.5 cm范围内,瑞利分布的特征参数在0.6-2.5之间。

Streamer inception delay,reflecting randomness of streamer inception characteristics under lightning impulse voltages,is an important part of streamer inception characteristics.The research on streamer inception time delay characteristics is help of revealing mechanism of long air gap discharge.Based on experiment results,the statistical time delay of effective free electron is considered as the major part of streamer inception time delay;according to effective free electron generation process,the probability density function was proposed to describe streamer inception time delay through the theoretical derivation;and a large number of experimental data was used for statistical analysis.The results show that streamer inception delay obeys Rayleigh distribution.The mean value of Rayleigh distribution represents the mean value of streamer inception delay and the variance of Rayleigh distribution represents the dispersion of streamer inception delay.The characteristic parameters of Rayleigh distribution has significant physical meaning and explains the trends of streamer inception delay well.The characteristic parameter of Rayleigh distribution is in range of 0.6 to 2.5,when the radius of rod electrode is from 0.5 cm to 2.5 cm and voltage rising rate is from 80 kV/ s to 240 kV/ s under positive lightning impulse voltages.