基于余弦距离和DBSCAN聚类的小电阻接地系统选线方法

Line Selection Method for Low Resistance Grounding System Based on Cosine Distance and DBSCAN Clustering

针对小电阻接地系统发生单相高阻接地故障时存在的保护死区问题,依据接地线路与正常线路零序电流相位存在明显差异的特点,提出一种基于余弦距离和DBSCAN聚类的小电阻接地系统选线方法,通过计算馈线零序电流余弦距离矩阵并结合DBSCAN聚类算法实现选线。对于工程中零序电流互感器极性错误,通过对零序电流进行预处理,进一步提高选线的可靠性。通过仿真验证所提方法在单相高阻接地、谐波干扰、零序电流互感器极性错误、同相两点接地、母线接地等情况下能可靠选线。

Aiming at the problem of protection dead zone in the case of single-phase high resistance ground fault in low resistance grounding system,according to the clear difference between the grounding line and normal line in phase of zero sequence current,a line selection method based on cosine distance and DBSCAN clustering for low resistance grounding system is proposed.The line selection is realized by calculating the zero-sequence current cosine distance matrix of the feeders and combining with the DBSCAN clustering algorithm.For the polarity error of the zero-sequence current transformer in the project,the reliability of line selection is further improved by preprocessing the zero-sequence current.Through simulation,it is verified that the proposed method can reliably select the line under the conditions of single-phase high-impedance grounding,harmonic interference,zero-sequence current transformer polarity error,non-inverting two-point connection,and bus bar grounding.