图6 K点发生单相接地故障前后电力系统的运行情况—中性点直接接地运行方式
如果K点的A相发生单相接地故障,则中性点与接地极构成单相接地短路回路,线路上将流过很大的单相短路电流,这是中性点直接接地方式与中性点不接地方式的最根本区别所在。相电压几乎不变,不产生过电压,设备绝缘水平低20%,造价低,节省了投资。因此,综合考虑系统可靠性、绝缘水平和继电保护的要求,中性点直接接地运行方式主要适用于:110kV及以上的电力系统和380/220V的电力系统。
5 结论和展望
本文利用PSCAD/EMTDC软件建立了简单电力系统的中性点运行方式的仿真模型,模拟了在各种运行方式下线路上发生单相接地故障时,电气参数的变化情况,并综合考虑系统可靠性、绝缘水平和继电保护的要求,确定了各种运行方式的适用范围。
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作者简介
梁越明(1965-),男,电气工程师,安徽省化工设计院。
钱玉娟(1964-),女,工程师,安徽省淮南市供电公司电力规划设计院。
韩平平(1981-),女,博士,讲师,合肥工业大学。■
本文关键字:仿真模型 其他电源技术,电源动力技术 - 其他电源技术