再议10kV线路避雷器雷电耐受技术参数的选用

Selection of Lightning Tolerance Technical Parameters for 10kV Line Arresters

10kV线路避雷器自身运行雷击损坏故障多发,归因为雷电耐受设计参数水平低缺乏充分论证。该文构建了10kV架空线路直击雷过电压瞬态过程计算模型,以冲击大电流幅值耐受超限作为避雷器本体雷击损坏的判据,计算获得线路避雷器故障临界雷电流,采用电气几何模型法统计得到线路避雷器的雷击故障概率,证明了现行技术标准规定的避雷器雷电耐受技术参数能够满足一般雷电强度地区的使用要求。进一步结合我国雷电活动区域分布特征,提出线路避雷器雷电耐受技术参数优化选择建议:用于雷电地闪密度小于4.71次/(km^(2)·a)的多雷区、中雷区、少雷区的线路,选择8/20μs标称放电电流为5kA、4/10μs大电流冲击为65kA;用于强雷区的线路和雷电地闪密度大于等于4.71次/(km^(2)·a)的多雷区的重要线路,选择标称放电电流为10kA、大电流冲击为100kA。并建议大电流冲击耐受试验采用整只避雷器本体为试品,促进生产工艺改良,改善线路避雷器产品实际雷电耐受性能与设计指标不匹配问题。

There is not sufficient evidence to attribute the lightning damages of the arresters on 10 kV distribution line to the low lightning tolerance level in the design parameters. This paper constructs a calculation model for the transient overvoltage process under direct lightning strikes. The magnitude of the surge current exceeding the withstand limit was used as the basis for judging the lightning damage to the arrester itself. Through calculation the critical current of the line arrester at failure was obtained. Then the electrical geometric model was used to calculate the lightning fault rate of the line arrester, which proves that the lightning withstands technical parameters of the arrester specified in the current technical standards can meet the requirements of the general lightning intensity areas. Further combining with the regional distribution characteristics of the lightning activity in China, the optimal selection of the lightning tolerance parameters of the line arrester was proposed: In more thunderstorm regions、middle thunderstorm regions and less thunderstorm regions, where the lightning-to-ground flash density is less than 4.71 times/(km^(2)·a), the line arresters on 10 kV distribution line, which has 8/20μs nominal discharge current with 5 kA and 4/10μs high current impulse with 65 k A, can be chosen;In strong thunderstorm regions and more thunderstorm regions, where the lightningto-ground flash density is equal to or more than 4.71 times/(km^(2)·a), the nominal discharge current and high current impulse of these line arresters should be 10 kA and 100 kA respectively. At the same time, it is recommended to use the entire arrester body as the test product in the high current impulse withstand test to promote the improvement of the production process and reduce the mismatch between the actual lightning withstand performance and the design index of the line arrester.