一种谐振接地系统的配电线路接地故障选线新方法

为解决小电流接地系统中发生故障时选线准确率低的问题,提出一种谐振接地系统单相接地故障选线新方法。通过分析不同线路的零序电流与零序阻抗特征,发现健全线路的零序阻抗始终呈容性,零序电流为纯容性电流;而故障线路零序电流在低频段含有消弧线圈的感性分量,且幅值大于高频段。先使用低通滤波器提取母线零序电压和各馈线零序电流在低频段的信号分量,并对母线零序电压求导;然后比较任意两条线路的零序电流与纯容性电流交叉相乘后乘积的差值,差值最大的为故障线路。分别对不同工况下的单相接地故障进行了仿真验证,结果表明,该方法选线准确,适应性强。

Line selection method for grounding fault in resonant grounding distribution systems

To solve the problem of low accuracy of line selection when grounding fault occurs in a small current grounding system, a new method for single-phase grounding fault line selection in resonant grounding system is proposed. By analyzing the characteristics of zero-sequence current and zero-sequence impedance of different lines, it is found that the zero-sequence impedance of the healthy line is always capacitive, and the zero-sequence current is the pure capacitive current. But the zero-sequence current of the faulty line contains the inductive component of the arc-suppression coil in the low frequency band, and the amplitude is greater than that in the high frequency band. Firstly, the low-pass filter is used to extract the signal component of the bus zero-sequence voltage and the zero-sequence current of each feeder in the low frequency band, and the bus zero-sequence voltage is derived. Then it compares the difference between the product of the zero-sequence current and the pure capacitive current of any two lines. The one which has largest difference is the fault line. Simulations of single-phase ground fault under different working conditions have been done. The results show that the method is accurate and adaptive. This work is supported by National Natural Science Foundation of China (No. 51677060).