降低配电线路避雷器雷击损坏概率对策研究

Research on Countermeasures to Reduce Failure Probabilities of Line Arresters due to Lightning Damage

安装避雷器是配电线路有效防雷措施,需要合理研究降低线路避雷器雷击损坏概率对策以延长避雷器运行寿命。采用EMTP软件建立10 kV线路模型,计算线路遭受雷电直击或雷电感应时避雷器两端电压,利用避雷器吸收能量计算避雷器损坏概率,分析采取改变避雷器通流容量、避雷线安装数量与安装方式、接地电阻等措施对于降低避雷器损坏概率的效果。研究结果表明:安装避雷线后,避雷器两端电压波形呈现较为明显振荡和衰减;避雷线数量的增加降低了避雷器两端电压幅值,导致避雷器吸收能量减少,遭受雷电直击时线路避雷器吸收能量远大于雷电感应情况。增加避雷器方波通流容量或避雷器安装数量能够降低避雷器损坏概率。避雷线数量的增加能够降低避雷器损坏概率,多条避雷线的推荐设置方式为从上向下将相线夹在中间。避雷器损坏概率随着线路接地电阻的增加而增大,因此需要尽可能降低线路接地电阻。在线路接地电阻难以降低情况下,可以通过缩短避雷线接地间隔来减小避雷器雷击损坏概率。

Line arrester is a typical lightning protection device,so it is necessary to study the countermeasures to reduce the lightning damage of line arresters.Equivalent model of 10 kV transmission line was established in EMTP to calculate voltages the line arrester.Failure probability was evaluated by means ofenergy absorbed by the line arrester.Influence of current capacity of arrester,number of arresters or ground wires,grounding resistanceand multi-point grounding spacing on failure probabilities were discussed.Results show that:overvoltage across the line arrester shows more apparent oscillation when the ground wire is installed.The increase of number of ground wires reduces the voltage amplitudes of the line arrester as well as the energy absorbed by the line arrester.Energy absorbed by the line arrester under the case of direct lightning is far greater than that under the case of indirect lightning.Increasing current capacity of arrester or the number of arresters can reduce failure probabilities of line arresters.Recommended setmode of multiple ground wires is from top to bottom where conductors are sandwiched in the middle.Failure probabilities of line arresters increase with the increasing of grounding resistance even when number of ground wires also increases.It is essential to reduce line grounding resistance and shortening the grounding spacingof the ground wire is practicable when the grounding resistance can hardly be reduced.