基于动态时间弯曲距离的小电流接地故障区段定位方法

A Fault Section Location Method for Small-Current Grounding Fault in Distribution Network Based on Dynamic Time Warping Distance

动态时间弯曲(dynamic time warping,DTW)距离可度量2个时间序列的相似性,且具有良好的耐同步误差特性和容错特性。配电网发生单相接地故障时,流过线路健全区段两侧的暂态零序电流几乎为同一电流,采样数据差异小,DTW距离也较小;而流过故障区段两侧的暂态零序电流存在明显差异,DTW距离较大;据此,提出一种基于暂态零序电流数据DTW距离的配电网小电流接地故障区段定位方法。当各馈线终端(feeder terminal unit,FTU)启动算法检测到接地故障发生后,将检测到的故障前后共1个工频周期的暂态零序电流采样数据上传主站,主站基于给定的故障区段搜索策略,通过计算相关暂态零序电流的DTW距离确定故障所在区段。该方法区段搜索效率高,故障定位速度快,各FTU启动时间同步误差及上传数据误码对定位准确性影响小。仿真结果验证了所提方法的正确性与有效性。

Dynamic time warping（DTW） distance can measure similarity of two time sequences, and has good characteristic in fault and synchronous error tolerance. When single-phase grounding fault occurs in distribution network, transient zero sequence currents through both sides of a healthy line section are almost the same, and thus determine a small DTW distance. While transient zero sequence currents through both sides of a fault line section are quite different, and lead to a bigger DTW distance. Accordingly, a novel method based on DTW distance is proposed to locate small-current grounding fault in distribution network. When starting algorithm of FTU detects that grounding fault occurs, it will send transient zero sequence current sampling data to master station. Based on given strategy of searching fault, the station calculates DTW distance of relevant transient zero sequence currents and determines fault section. This method has features of high searching efficiency and fast fault location, and is affected rarely by synchronization error of each FTU and individual sampling error of uploading data. Simulation results verify correctness and validity of this method.