基于滚球法的变电站直击雷防护设计

Rolling Sphere Method Based Design of the Direct Lighting Strike Protection for Substations

针对折线法用于变电站直击雷防护存在着一些不足,基于滚球法原理,提出了以计算多支避雷针保护时最小滚球半径值为基础的防雷设计方法。该方法依据滚球立体几何模型,建立空间坐标系,求解方程组得出最小滚球半径值,计算介于最小滚球半径值对应的雷电流以及设备所能承受的雷电流两者之间的雷电流概率,结合该地区年平均雷暴日确定设备的雷击故障率。运用该方法对计算实例进行了分析,结果表明了该方法具有可行性。

Aiming at the certain shortages of the polygon method for the direct lighting strike protection of substations,and based on the principle of rolling sphere method,this paper proposes a method of lightening-protection design,which employs the calculated minimum ball radius for several lightning rods.According to the model of solid geometry for rolling sphere,and establishing a space coordinate system,the method obtains the minimum ball radius by solving a system of equations,and calculates the lightning current probability which falls in between the lightning current corresponded with minimum ball radius and that endured by equipments,and determines the lightning strike failure rate of equipments in a way to consider the average thunder storm days per year in the area.A case study is carried out,and it proves that the proposed method is feasible.