雷击输电线路对并行10 kV配电线路影响分析

由于线路走廊有限,10 kV配电线路与输电线路会出现并行架设,需要分析输电线路遭受雷击后对配电线路防护产生的影响。文中分析输电线路避雷线遭受雷击对配电线路的电磁影响及输电线路对配电线路的屏蔽保护作用,利用EMTP软件建立输电线路与配电线路模型,计算雷击输电线路避雷线时配电线路感应过电压,分析避雷线高度、线路间水平间距、线路高度差和输电线路杆塔接地电阻对感应过电压的影响。分析结果表明:雷击输电线路避雷线时,配电线路感应过电压随着避雷线高度的增加而降低,但降低趋势趋缓。过电压随着二者间水平距离的增大而减小,且水平距离越远,降低幅度越大,过电压随二者高度差的增大而减小,高度差越大,减小幅度越大。线路感应过电压随着输电线路接地电阻的增大而增加。接地不良情况下线路感应过电压十分容易超过其绝缘水平,因此需要尽可能降低输电线路杆塔接地电阻。

Analysis of Influence of Lightning Strike Transmission Line on Parallel 10 kV Distribution Line

10 kV distribution lines may parallel with transmission lines due to the limit of line corridor, so it is necessary to study the interference on 10 kV distribution line when lightning strikes on the parallel transmission line. Shielding effect of transmission lines and interference of transmission line under lightning on distribution line are analyzed. Coupled electrical circuits of distribution lines and transmission lines are also established in EMTP to calculate induced overvoltage on the distribution line. Effects of height of the shielding line, distance and height difference of the transmission line from the distribution line and ground resistance of the transmission tower on induced overvoltage are discussed. The results show that: induced overvoltage on the distribution line decreases as the increment of height of the shielding line and distance of the transmission line from the distribution line of the height difference, but change trends of induced overvoltage are opposite. Induced overvoltage increases with the rise of ground resistance of the transmission tower. Bad grounding of the transmission tower will result in insulation problem, so it is necessary to reduce the ground resistance as low as possible.