变电站防雷设计标准的选择

Selection of Design Standards for Substation Lightning Shield

折线法和滚球法是国内防雷保护设计人员熟知的两种方法。由于GB 50057标准没有明确说明此标准不适用于电力线路和变电站设计,GB/T 50064标准又没有引入滚球法,导致国内设计人员常错误的将GB 50057规定的滚球法做为变电站防雷设计的依据。通过对GB、IEC、IEEE等防雷标准对比,明确了变电站防雷设计应采用的方法和采用滚球法时应参考的标准。对于变电站防雷设计而言,两种方法都可采用。如采用滚球法,滚球半径的选择可采用IEC61936-1或IEEE 998规定的方法,而不应采用GB 50057、IEC 62305或NFPA 780规定的方法。同时通过实例计算比较了折线法(GB/T 50064)和滚球法(IEC61936-1)的变电站防雷保护范围并依据IEEE 998规定的滚球法计算了变电站防雷保护失效率。

Polygon method and rolling sphere method are two common method for lightning protection calculation.Since GB 50057 standard does not clearly state that this standard is not applicable to the design of power transmission lines and substations and GB/T 50064 does not introduce the rolling sphere method,domestic designers often mistakenly use the rolling sphere method specified in GB 50057 as the basis for lightning protection design of substations.The applicable lightning protection method of substation has been specified and the correct reference standards have been recommended when rolling sphere method was adopt in the design by comparing of different standards of GB,IEC,IEEE etc.Both method are applicable for substation lightning shield design.The radius of rolling sphere can be sized according to IEC 61936-1 or IEEE 998 if rolling sphere method is adopted,but not the standard of GB 50057,IEC 62305 or NFPA 780.Meanwhile,the protection area of rolling sphere method of IEC61936-1 and the one of polygon method of GB/T 50064 are compared and the failure rate of lightning protection which are based on rolling sphere method of IEEE 998 has been calculated.