棒极结构对棒–板间隙操作冲击放电特性影响的试验研究

Influence of Rod electrode Structure on Switching Impulse Discharge Characteristics of Rod-plane Air Gap

棒-板间隙是研究空气间隙放电的最典型间隙，其操作冲击放电特性是输电工程线路和换流站／变电站空气间隙选择的重要依据之一。为了更深入地研究棒-板间隙的操作冲击放电特性，选择不同直径的棒电极，以及半球彤和圆锥形2种棒电极端部形状，在2～5m间隙距离下进行了正极性操作冲击放电特性的试验，得到了棒电极端部形状和棒电极直径的改变对棒-板间隙正极性操作冲击50％放电电压造成的影响。另外，在北京、西宁和羊八井等几个不同海拔地区进行了临界半径的对比试验。通过改变棒电极端部连接球面的半径，得到了不同间隙距离对应的临界半径。由试验可以得出，当棒电极结构的半径小于临界半径时，棒电极半径和端部形状的改变不会对间隙的50％放电电压产生明显影响；临界半径随间隙距离的增加而增加，且随着海拔高度的增加，同一间隙对应的临界半径也随之增加。

Rod-plane air gap is the most typical gap in the research of air gap discharge, and its switching impulse characteristic is a very important factor for dimension of air gaps in the project design of transmission lines and converter stations/substations in transmission project. To study switching impulse characteristic of rod-plane air gap deeply, positive switching impulse discharge tests were carried out using rod electrodes with different diameters, hemisphere and cone shape in their heads. The influence of shape and diameter of rod electrode on 50% flashover voltage was concluded. To obtain the critical radius at different altitudes, comparison tests were carried out in Beijing, Xining and Yangbajing, and the critical radius corresponding to different gap distances were obtained through changing the radius of sphere connecting rod electrode. It is shown that when radius of rod electrode is less than critical radius, the change of radius and shape of rod electrode will not affect 50% flashover voltage of air gap; The critical radius will increase when gap distance increases, and the critical radius corresponding to a certain gap distance will increase at high altitude.