一种计算高速铁路绕击闪络率的新方法

为了更准确地计算高速铁路雷电绕击闪络率,须考虑到雷电先导的随机性。针对暴露距离的电气几何模型在工程防雷计算中,没有考虑雷电先导带有入射角的缺陷,对应用暴露距离理念的电气几何模型进行改进,将暴露距离的概念延伸至带有任何入射角度的雷电先导中,推导出应用暴露距离计算带雷电入射角的雷电先导绕击高速铁路的受雷面积,再根据入射角的绕击范围和出现概率推导出整体考虑在与加强线和正馈线处于同一截面内改变的雷电入射角的闪络率计算公式。最后根据不同高架桥高度对高速铁路绕击闪络率进行计算分析。应用改进后的模型计算出来的高速铁路绕击闪络率,相比应用暴露弧投影方法计算出来的结果要小,既克服了暴露弧投影计算方法结果偏大的缺点,又相比传统暴露距离方法更接近实际,为高速铁路的防雷提供重要参考依据。

A New Method to Calculate Lighting Flashover Rate of Shielding Failure of High Speed Railway

In order to calculate more accurately the rate of shielding failure of high speed railway,the random character of lighting antecedence should be taken into account. With a view to the failure to take into account of the lightning strike angle in the calculation of engineering lighting proof with electrogeometric model( EGM) applied to the expose distance,the model is improved to extend the concept of expose distance to any thunder and lightning at any lightning strike angle,the shielding failure area of high speed railway is deducted by means of the exposed distance to calculate lightning strike angle,the formula is concluded on the basis of the scope of shielding failure angle and the probability of occurrence to calculate high speed railway lightning shielding failure flashover rate where the reinforced line and the positive feeding line are in the same cross section. Finally,the flashover rates of shielding failure resulted from different elevated bridges are calculated and analyzed. The flashover rate of shielding failure of high speed railway is smaller calculated with improved model than that calculated with exposure arc projection,which not only overcomes the shortcoming that the calculation results of the exposure arc projection are bigger,but is closer to the practical situation compared with the traditional exposure method,and provides references to high speed railway lightning protection.