长空气间隙负极性操作冲击放电特性研究(Ⅲ)——统计特性

Research on Typical Long Air Gaps With Negative Switching Impulses(Ⅲ) ——Statistical Character

空气间隙的放电特性参数具有统计特性,采用数理统计和有限元数值仿真两种方法对空气间隙的放电特性开展了研究。数理统计结果显示:下棒电极高度对棒–棒长空气间隙的50%负极性操作冲击放电电压有一定的影响;20/2 500μs操作冲击电压作用下,棒–棒间隙和棒–板间隙的平均击穿时间基本出现在波尾;80/2 500s操作冲击电压作用下,棒–棒间隙和棒–板间隙的平均击穿时间基本出现在波头;10 m棒–板间隙放电电压服从正态分布,棒–棒间隙的伏秒特性低于棒–板间隙的伏秒特性。静电场计算结果显示:电场不均匀系数随着间隙距离的增大而增大,而间隙距离与电场不均匀系数的比值随着间隙距离的增大呈现饱和趋势,定性地解释了长间隙负极性操作冲击放电的饱和特性。所做工作对特高压输电线路绝缘配合设计具有一定的指导意义。

There are statistical parameters in long air gap discharge. Mathematical statistics and finite element simulation were both employed to research deeply on the discharge characteristics. Statistical results indicate that there＇s a slightly influence of grounding rod height on the 50% discharge voltage of rod-rod air gaps; breakdown time is almost higher than the wave front time with 20/2 500μs switching impulse and it is lower than the wave front time with 80/2 500 μs; the distribution of discharge voltage in 10 m rod-plane gaps obeys the normal distribution; and the V-t characteristics of rod–rod gaps is lower than that of rod-plane. Calculation results indicate that nonuniform coefficient of electric field increases with increasing gap distance; the ratio of gap distance and nonuniform coefficient also increases with the gap distance but tends to level off, indicating a saturated discharge voltage with gap distance. The work conducted in this paper can provide preference to the insulation coordination designation of UHV transmission lines.