正极性操作冲击电压下流注发展过程中空间电场变化规律

Variation Law of Spatial Electric Field During the Development of Streamer Under Positive Switching Impulse Voltage

流注放电过程具有弱发光、电离程度高等典型特征,定量分析流注发展过程中光信号和空间电场跃变规律,对于加深流注放电过程机理认识、提升间隙绝缘性能具有重要意义。利用电场传感器、光电倍增管、罗氏线圈等设备搭建光电联合检测系统,对正极性标准操作冲击电压下10 cm针–球间隙的放电发展过程中瞬时光功率、空间电场和接地极放电电流进行测量。试验结果表明:电晕起始时,流注产生紫外光并引起空间电场的畸变,针电极头部发光越剧烈,其附近出现的强电荷群在空间建立的电场也越大;间隙击穿时,空间电场畸变明显,流注发光先于间隙击穿被光电倍增管测量到,有负极性电流流过地电极。通过对不同电压下的瞬时光功率和电场进行对比分析可知,利用电场传感器可判断流注的起始时刻以及流注电离的剧烈程度。

The streamer discharge process has typical characteristics such as weak luminescence and high ionization.It is of great significance for deepening the mechanism of streamer discharge process and improving the gap insulation performance to quantitatively analyze the optical signal and spatial electric field distortion law during the development of streamer.Consequently,we adopted photoelectric integrated electric field sensor,photomultiplier tube,Rogowski coil and other equipment to build a photoelectric combined detection system so as to measure the instantaneous optical power,space electric field,and ground electrode discharge current during the discharge development of the 10 cm needle-ball gap under positive standard switching impulse voltage.The test results show that,at the beginning of corona,the ultraviolet light generated by the streamer will cause the distortion of the electric field;the more intense the light of streamer of the needle electrode is,the larger the electric field established in the space will be.When the breakdown occurs in the gap,the spatial electric field distortion is obvious,the streamer is observed by the photomultiplier tube before breakdown,and a negative current flows through the ball electrode.Comparison and analyses of the instant optical power and electric field under different voltages reveal that the electric field sensor can be ultized to judge the moment of initiation of the streamer and the intensity of the streamer.