不同配网支线拓扑结构下电能采集终端雷电感应过电压防护分析

配电网面临较为严重雷电感应过电压威胁,需要分析不同支线拓扑结构下电能表等采集终端设备的过电压防护。利用EMTP软件搭建配网模型,通过model模块编程计算不同支线拓扑结构下电能表雷电感应过电压,讨论终端过电压幅值统计特性,分析土壤电阻率、220 V线路长度等因素的影响,最后讨论入户处安装SPD对电能表感应过电压的抑制效果及其受接地电阻的影响。研究结果表明:电能表感应过电压随着距雷击点距离的增加而降低;不同拓扑结构下,同一节点分支数量越多,邻近电能表过电压越低,但过电压波形震荡越剧烈。相同条件下,电能表受雷电感应过电压威胁程度从高到低依次为链形结构、H形结构和星形结构。电能表终端过电压出现高幅值的概率随着土壤电阻率和220 V架空线长度的增加而增大。入户处安装SPD后,电能表感应过电压能够得到有效抑制,但为了更有效防护内部芯片等敏感设备,需要尽可能维持较低的SPD接地电阻。

Lightning induced overvoltage protection for acquisition terminals under different topology structures of branch lines in the distribution networks

Lightning induced overvoltage is one of serious threatens to distribution networks, so it is necessary to analyze surge protection for acquisition terminals under different topology structures of branch lines. Equivalent model of 10kV distribution network was established in EMTP and induced overvoltage of the watt-hour meter under different typical topology structures of branch lines was calculated by means of model programming. Statistical characteristics of the overvoltage magnitude were presented. Influence of soil resistivity and length of power line on the overvoltage magnitude were discussed. Finally, protection effect of the terminal SPD and effect of its grounding resistance were analyzed. Research results show that: induced overvoltage of the watt-hour meter decrease with the increasing of distance from lightning locations. Rise number of branch lines on the same node results in a decrease of overvoltage and an increase of intensive waveform oscillation. Under the same conditions, threat level from high to low was: chain shape, H shape and star shape. The occurrence probability of high amplitude increases with the increasing of soil resistivity and length of power line. Overvoltage of the watt-hour meter can be inhibited significantly when installing the terminal SPD, but it is essential to maintain a lower grounding resistance as long as possible in order to protect the sensitive equipment effectively.