输电线路雷击暴露空间的三维计算方法研究

雷击暴露宽度对于准确评估输电线路的防雷性能起着重要作用。基于导地线对地高度与输电线路雷击暴露宽度之间的非线性关系,发现EGM中采用等面积法将平均高度处的暴露宽度积分和替换输电线路沿线各处的暴露宽度积分和时存在不可控误差,据此提出了输电线路雷击暴露宽度的三维拓展方法,将传统计算方法中的雷击暴露宽度沿着输电线路每个档距拓展为三维暴露空间,并推导了由暴露宽度组成的暴露空间的三维计算公式与采用暴露空间的绕击跳闸率计算公式。以500kV双避雷线输电线路为例,计算了输电线路档距内雷击暴露宽度三维分布与雷击暴露宽度积分和的二维分布,分析发现该方法可以规避EGM中由暴露宽度导致的不可控误差,能够直观地分析输电线路不同位置的雷击暴露情况,可为输电线路防雷性能的精确计算与差异化防雷的定量分析提供参考。

Study on Three-Dimensional Calculation Method of Lightning Exposed Space of Transmission Lines

Lightning exposed width plays an important role in accurately evaluating lightning protection performance of transmission line.Based on the nonlinear relationship between conductor height and lightning exposed width of transmission lines as well as overhead ground wires and width,the uncontrollable error is found in EGM when exposed width integral sum in everywhere alone transmission lines is replaced by exposed width integral sum in average height of transmission lines using homolographic calculation method.In this paper,three-dimensional expanding method of exposed width in which lightning exposed width is expanded to three-dimensional exposed space is proposed,the three-dimensional calculation formulas of exposed space composed of exposed width and shielding failure trip-out rate adopting exposed space are derived.Take 500kV transmission line with two overhead ground wires for example,the three-dimensional distribution of lightning exposed width and the two-dimensional distribution of lightning exposed width integral sum in a span of transmission lines are calculated,found that the uncontrollable error resulting from exposed width in EGM could be avoided,lightning exposure distribution alone different place of transmission lines could be intuitively analyzed using this method.The calculation results are available for reference to accurate calculation of lightning protection performance of transmission lines and quantitative analysis of differentiated lightning protection.