基于测量阻抗等值面积的柔性直流配电线路单端量保护方案

A Single-Ended Protection Scheme for Flexible DC Distribution Lines Based on Measuring Impedance Equivalent Area

中文关键词:柔性直流配电系统  线路保护  小波变换  模糊C均值聚类  单端量保护

keywords:flexible DC distribution system  line protection  wavelet transform  fuzzy C-mean clustering  single-ended quantity protection

中文摘要:直流配电线路受设备采样频率的约束，保护方案难以兼顾速动性与可靠性。提出一种基于测量阻抗等值面积和模糊C均值聚类分析的柔性直流配电线路单端量保护方案。计算分析保护安装处测量阻抗的小波变换模极大值，以此构造启动判据；理论分析故障初始阶段故障电压、电流及测量阻抗的变化规律，利用电容放电阶段测量阻抗等值面积进行故障识别；根据历史数据对测量阻抗进行离线FCM聚类分析，比较实时数据与聚类中心的欧式距离以实现故障选极；在PSCAD仿真平台对不同工况进行仿真测试，仿真结果表明：保护方案可以实现对故障的快速可靠识别，并可以有效耐受过渡电阻和噪声干扰。

Abstract:As DC distribution lines are constrained by the sampling frequency of the equipment， it is difficult for the protection scheme to take into account the rapidity and reliability at the same time. To this end， a single-ended protection scheme for flexible DC distribution lines is proposed based on the equivalent area of measured impedance and fuzzy C-means clustering analysis. Firstly， the wavelet transform mode maxima of the measured impedance at the protection installation is calculated and analyzed to construct the startup criterion； secondly， the variation rules of fault voltage， current and measured impedance in the initial stage of the fault are theoretically analyzed， and the equivalent area of the measured impedance in the capacitive discharge stage is used to carry out the fault identification； thirdly， the offline FCM cluster analysis of the measured impedance is performed based on the historical data to realize the fault selection by comparing the Euclidean distance between the real-time data and the clustering center； finally， simulation tests are carried out in the PSCAD simulation platform for different working conditions， and the results show that the proposed protection scheme can realize fast and reliable identification of faults， and can effectively withstand transition resistance and noise interference.