基于变电站雷电安全运行年的避雷线塔空气击距简化计算方法

Simplified Calculation Method for Air Striking Distance of Lightning Protection Towers Based on Lightning Safe Operation Years in Substation

摘要:

针对规范中对避雷线塔与保护设备间的空气击距取值要求不明确，在实际变电工程中存在裕度过大的问题，提出了一种空气击距简化计算方法。首先，在分析避雷线塔的冲击接地电阻影响因素和避雷线的雷电分流效应的基础上，采用基于变电站雷电安全运行年数的概率法，根据变电站的具体布置尺寸，对比变电站实际每年遭受雷击的概率，确定避雷线塔空气击距的临界雷击的概率；然后，通过雷电流的概率分布，求得对应临界雷电流的幅值，并根据雷击避雷塔暂态电位简化模型和雷电冲击穿场强，获得避雷线塔与被保护设备间空气击距的简化计算方法；最后，结合实际变电站案例，进行了基于变电站雷电安全运行年数的避雷线塔空气击距计算，类比规范计算方法提出相应的简化计算公式，并分析了空气净距取值对变电站电气布置的影响。

Abstract:

Due to the unclear value requirements for air striking distance between lightning protection towers and protected equipment in the regulations, there is often excessive margin in the actual power transformation projects. Firstly, based on the analysis of the factors affecting impulse grounding resistance and the lightning diversion effect of lightning protection lines, the probability method based on lighting safe operation years in substation is adopted, and according to the layout of substations, the actual annual lightning stroke probability is compared to determine the critical lightning stroke probability of air striking distance of lightning protection towers. Secondly, the amplitude of the corresponding critical lightning current is obtained through the probability distribution, and, based on the simplified transient potential model of lightning protection towers and breakdown field, a simplified calculation method for determining the air striking distance between lightning protection towers and protected equipment is obtained. Finally, based on actual substation cases, the calculation is carried out, the corresponding simplified calculation formula is proposed and the influence of air clearance on the electrical layout of substations is analyzed.