配电线路架设地线对雷电感应过电压的防护效果

Protective Effect of Erecting Ground Wire on Distribution Line to Lightning Induced Overvoltage

雷电感应过电压是10kV架空配电线路雷电防护的主要对象,架设地线对雷电感应过电压的防护效果是工程中重点关注的问题。为此,建立了有地线线路的感应过电压计算模型,仿真研究了电杆接地电阻和地线位置对地线限制感应过电压效果的影响,根据研究结果,建议将地线架设在导线上方,在满足线间距离要求的情况下,尽量将地线靠近导线,电杆可自然接地。对不同大地电阻率和绝缘子闪络电压条件下,线路的雷电感应过电压闪络率进行了计算,结果表明,线路的雷电感应过电压闪络率随着大地电阻率的增大和绝缘子闪络电压的降低而呈上升趋势,架设地线可将线路的雷电感应过电压闪络率降低约72.2%～84.1%,架设地线对雷电感应过电压具有较好的防护效果。

Lightning induced overvoltage is the main object of lighting protection for 10 kV overhead distribution lines, and the protective effect of erecting ground wire against lightning induced overvoltage is a common focus in actual projects. Firstly, we established a lightning induced overvoltage calculation model of distribution line with ground wire. Then, by numerical simulation, we analyzed the inhibitory effect of erecting ground wire to lighting induced overvoltage, including the influences of ground wire position and grounding resistance of tower. According to the analysis results, it is recommended that the position of ground wire should be above and close to phase conductor while keeping the range of safety distance, and towers may be naturally grounded. Finally, we calculated the lightning induced overvoltage flashover rates of distribution lines with different ground resistances and different insulator flashover voltages. The results show that, the lightning induced overvoltage flashover rate rises with increasing ground resistivity and decreasing insulator flashover voltage, and erecting ground wires can reduce the overvoltage flashover rate by 72.2% -84.1%.It is concluded that erecting ground wire can provide an effective protection against lightning induced overvoltage.