小电流接地故障选线技术与验证

The Fault Line Selection Technologies for Small Current Grounding Fault and Its Validation

小电流接地故障选线方法及装置种类繁多,由于缺乏综合性能对比,电网公司在产品选型时存在一定盲目性,选线装置实用效果总体不佳。介绍了国内主流选线装置的基本原理,以及一次人工接地试验的情况。试验表明,不同选线技术性能差异较大,以暂态法和注入电流法(通过调整消弧线圈失谐度或在中性点附加中电阻向系统注入电流)为代表的选线技术效果良好,而传统利用故障工频电流、谐波电流的选线方法效果不佳;此外,相同选线原理的不同厂家产品性能也有一定差异。需要注意的是,优秀的选线技术只有配合良好的装置设计及现场安装、维护,才能充分发挥其技术优势,保证选线准确度。

There are many different kinds of fault line selection methods and devices for small current grounding fault. Due to lack of comparison for them with comprehensive performance, power grid company chooses the fault line selection devices blindly which lead to low performance of these devices in practice. The basic principle of major fault line selection devices and the situation of an artificial grounding test are introduced. It is proved that performances of different devices vary in different regions. The transient methods which is using the transient voltage and current during the single-phase earth fault, and the injection current methods which is tuning the Petersen coils or shunting an additional resistance between the neutral point and ground to produce the injection current perform well, while the traditional method using power frequency current and harmonic current does not perform very well. Moreover, there are performance differences between the devices made by different manufacturers with the same selection principle. One thing needs need to pay attention to is that only with the good device design, field installation and maintenance; the advantages of an excellent fault line selection method can be fully taken to guarantee the accuracy of fault line selection.