基于不均匀系数的气体冲击击穿电压计算方法研究

Calculation Method Research of Gas Breakdown Voltage Based on Un-uniform Factor

针对高压电气设备气体绝缘,间隙的伏秒特性虽能全面反映冲击击穿特性,但求取繁琐,工程实际中常用50%冲击电压UBD,50%来表示间隙的冲击击穿特性。文中利用电场不均匀系数ζ本身的特性,提出一种基于ζ的气体冲击击穿电压值UBD,50%计算方法,并以0.4 MPa干燥空气和0.5 MPa氮气为例,结合数值仿真和有限次试验值,得到电场不均匀系数ζ与Emax,50%的函数关系,从而可以得到不均匀系数ζ不同时对应的UBD,50%,并对其计算结果进行了误差分析,误差在7%以内,从而验证了计算方法的有效性。

For gas insulation of high voltage electrical equipment, U-t characteristic is able to fully reflect impulse breakdown characteristic of gap. Owing to take it complexly UBD,50%will be commonly used to describe the characteristic in engineering practice. In this paper, a computational method of gas impulse breakdown voltage UBD,50%has been proposed based on un-uniform factor of electric field. Considering dry-air with 0.4 MPa and N2 with 0.5 MPa as examples, a function relationship between electric field un-uniform factor ζ and a small amount of Emax,50%experimental values can be obtained by combining numerical simulation with experiment. UBD,50%can be calculated by the formula with the change of ζ. Finally the error of calculation results is analyzed. The error is less than 7% which verifies validity of the computational method.