杆塔接地装置的冲击阻抗建模及应用

Impulse Impedance Modeling and Application of Tower Grounding Device

杆塔冲击接地阻抗是输电线路雷击跳闸的主要影响因素之一,在我国的山地、丘陵地区,杆塔冲击接地电阻往往较高,使得线路跳闸事故频发。该文基于有限元与电路理论结合的方法,通过试验探究了广东地区典型土壤的冲击特性,建立了精确的输电线路接地暂态模型,基于该模型探究了地表下存在岩层区的输电杆塔冲击降阻优化方法。研究结果表明,对于地表下存在岩层区的接地装置,使用外引射线配合针刺短导体以及外引射线配合垂直接地极有着较好的优化效果。其中,外引射线配合针刺短导体时,针刺长度为射线的3%~6%、针刺间距为射线的10%~14%时降阻效果最好;外引射线配合垂直接地极时,垂直接地极布置于射线最外端时降阻效果最好。研究结果可为山区杆塔接地改造和优化提供参考和理论支持。

Tower grounding impedance is one of the main influencing factors of lightning trip accidents on transmission lines. In the mountainous and hilly areas of China, the tower usually has a large impulse grounding resistance, which causes frequent line trip accidents. Based on the combination of finite element method and circuit theory, this paper explored the impulse characteristics of typical soils in Guangdong and established a precise grounding transient model of transmission lines. Based on this model, an optimization method for the impulse resistance reduction of transmission towers in rock zones was studied. The results show that for grounding devices with rock formations below the earth surface, the application of external grounding electrodes with short conductors and external grounding electrodes with vertical grounding electrodes has a better optimization effect. If the short conductors are used to match external grounding electrodes, the effect of reducing the resistance is the best when the length of the short conductor is 3%~6% of the external grounding conductor and the spacing of the short conductors is 10%~14% of the external grounding conductor. If the vertical grounding electrodes are used to match external grounding electrodes, the effect of reducing the resistance is the best when the vertical grounding electrodes are placed at the outermost ends of the external grounding conductors. The results can provide reference and theoretical support for grounding transformation and optimization of mountain towers.