雷电流对杆塔接地装置冲击特性 影响规律的研究
Influence of Lightning Current on Impulse Characteristic of Ground Device of Pole and Tower

针对由于雷击输电线路或杆塔所致的电力系统线路跳闸率较高的现象,建立了一种不同幅值雷电流作用下杆塔接地装置冲击系数模型,以用于雷电流对杆塔接地电阻影响的评估计算,提高冲击接地电阻的测量准确度。搭建了土壤火花放电X光拍摄平台,在不同雷电流作用下,得到土壤火花放电具有斑点状-球状-流注状-电弧通道的渐变过程规律,通过不同大小雷电流现场试验,得出不同冲击电流下电感效应对电流阻挡作用及火花效应的散流作用相互制衡关系,进一步通过电感效应与火花效应解耦的方法得到较准确的接地装置冲击电阻。试验结果表明,所建模型实现了通过小雷电流冲击测试得到大雷电流作用下接地装置冲击特性的目的,并可通过小型便携式冲击接地阻抗测试仪,对杆塔冲击接地阻抗进行测试,所计算阻抗与实际阻抗的误差在3％以内,可对输电线路防雷设计、评估、施工、改造等起到指导作用。
According to the phenomenon that higher line trip rate of power system is often caused by lightning strike, an impact coefficient model of ground device of pole and tower for different lightning current amplitude is established to evaluate the impact of lightning current on grounding resistance of the pole and tower, and improve impulse grounding resistance measurement accuracy. X？？ray photograph platform is constructed to get the gradual change law of spark discharge in soil along spot-sphere-streamer-arc channel under lightning current. Via field test under different lightning current, the interaction of the effect of inductance effect on the current blocking action and the effect of the spark effect on flow are revealed. The impact resistance of the grounding device is obtained by decoupling the inductive effect and the spark effect. Experiment results show that with the proposed model the impulse characteristic of the ground device under large lightning current can be obtained via measurement under small lightning current. Hence, portable ground impedance tester can be adopted to measure impulse ground impedance, and the error between the calculated impedance and the actual one is less than 3％