基于PSCAD/EMTDC软件的配电线路感应过电压计算方法

对配电线路的感应过电压及耐雷性能进行研究。通过相模变换将Agrawal模型转换为模量的波动方程,根据特征线法对波动方程进行分析,得到感应过电压的等值计算电路,并对雷电电磁场的计算方法进行简化。建立感应过电压在PSCAD/EMTDC软件中的计算模型,与数值计算方法比较以验证模型的准确性,分析土壤电阻率对感应过电压的影响及避雷器、耦合地线降低感应过电压的效果。结果表明,应对土壤电阻率较高地区配电线路重点保护;线路绝缘水平较低时(150 kV)要有效降低感应过电压,在土壤电阻率较低、较高时避雷器间距分别不宜大于400 m、200 m,绝缘水平较高(300 kV)且土壤电阻率较高时,避雷器间距不宜大于400 m;耦合地线与线路高度差越小,降低感应过电压效果越明显。

Calculation model of lightning induced overvoltage using PSCAD/EMTDC program for overhead distribution lines

In order to study the lightning induced overvoltage(LIV) and lightning performance of distribution lines, the Agrawal model was converted to modal expression using the similarity transformation, and the expression was analyzed with the method of characteristics. An equivalent calculating circuit of LIV was obtained with the analysis with which a calculating model in PSCAD/EMTDC was proposed and verified for the accuracy of the model. The influences of soil resistivity, surge arrester and coupling ground wire on LIV were also analyzed. The results show that, distribution lines located in high soil resistivity region should be protected with particular emphasis; for low insulation lines, the LIV is dramatically diminished when the soil resistivity is low and arrester installation interval is less than 400 m, or the soil resistivity is high and arrester installation interval is less than 200 m; for high insulation level lines, the arrester installation interval should be less than 400 m when the soil resistivity is high; and lastly the smaller the altitude difference between line conductors and neutral conductor is, the larger the lightning induced voltages decrease.