正极性操作冲击电压下流注放电路径随机发展特性

Stochastic Development Characteristics of Streamer Discharge Channel Under Positive Switching Impulse Voltage

流注放电具有分散性和随机性的典型特征,研究流注放电过程中起始时延分散性、发展路径随机性等因素对于加深放电过程机理认识、提升间隙绝缘性能具有重要意义。本文结合流注起始判据及分形理论建立了考虑空间电荷屏蔽效应的空气间隙动态流注随机发展计算模型,仿真模拟了棒-板、锥-板等间隙结构放电路径发展过程,得到了流注起始时延、发展形态、发展速度及空间电荷量等特征参数,并搭建光电联合检测平台获取试验值进行对比分析,验证了模型的有效性。仿真结果表明:在标准操作冲击电压作用下,电极曲率半径增大,起始时延分散性增加;随着外施电压上升率从0.45 kV/μs上升至11.15 kV/μs,棒-板间隙流注轴向发展速度从5.70×10^(5) m/s增加至8.32×10^(6) m/s,放电通道分形维数自1.19增加至1.28,放电树枝分叉增多,放电路径随机性增加。

The streamer discharge process has typical characteristics such as dispersion and randomness.It is of great significance for deepening the consciousness of mechanism of discharge process and improving the gap insulation performance to study such factors as dispersion of initial delay time and randomness of discharge channels during the streamer discharge propagation.In this paper,the stochastic development calculation model of air gap dynamic streamer under space charge shielding was established by combining the streamer initiation criterion and fractal theory.The discharge propagation of the rod-plane and cone-plane gap structures were simulated and the characteristic parameters such as streamer initiation delay,discharge morphology,propagation velocity and space charge were obtained.A photoelectric combined detection platform was built to obtain the test values for comparative analysis,and the effectiveness of the model was verified.The simulation results show that the dispersion of initial delay increases with the increasing of electrode radius of curvature under the action of standard operating impulse voltage.With the increase rate of applied voltage from 0.45 kV/μs to 11.15 kV/μs,the axial average streamer velocity of rod-plane gap increases from 5.70×10^(5) m/s to 8.32×10^(6) m/s,and the fractal dimension of discharge channel increases from 1.19 to 1.28,which means that the number of discharge branches increase and the randomness of the discharge path increases.