基于时频原子灰色关联的小电流接地故障选线方法

A novel fault line selection method based on time-frequency atom decomposition and grey correlation analysis of small current to ground system

提出一种时频原子灰色关联的小电流接地故障选线方法。根据当前小电流接地系统分支线路数目,计算故障线与非故障线的线路基准值;以Gabor原子库为索引,利用匹配追踪法将各分支线路故障后首个1/4周期内的暂态零序电流进行时频原子分解,求得表征各分支线路故障特征信息的衰减正弦量原子;采用改进灰色关联分析对各衰减正弦量原子进行关联度分析,求得各分支线路的特征值;将各特征值分别与故障线和非故障线的基准值求欧式距离并比较大小,通过所求欧式距离大小的比较,可实现准确选线。仿真结果表明,该方法计算量小,选线精度高,尤其适用于多分支线路的小电流接地系统。

This paper proposed a small current to ground fault line selection method with time-frequency atom and grey correlation analysis. Firstly, it calculated the base values of fault line and non-fault line based on the number of branch line of small current to ground system. Secondly, it used the matching pursuit method to decompose the transient zero- sequence current of the first 1/4 cycle indexed by Gabor atom, and calculated the damped sinusoidal atoms of every branch line which expressed the characteristic of fault state. Thirdly, it used the theory of grey relational analysis to compute the correlation degree of every damped sinusoidal atom, and got the characteristic value of every branch line. Finally, it calculated the Euclidean distance value between the characteristic values and the base values of fault line and non-fault line, and compared the size of Euclidean distance values to achieve the fault line selection accurately. The method has a lower computational complexity, an accurate fault selection proved by a large number of simulations. It is especially suitable for the multi-branch lines of small current to ground system.