基于Pearson相关系数与广义S变换的低压直流微电网的故障选线方法

Fault line selection method of a low-voltage DC microgrid based on the Pearson correlation coefficient generalized S-transform

针对低压直流微电网线路的故障选线方法的研究有限,提出一种基于Pearson相关系数与广义S变换的故障选线方法。首先,介绍了低压直流微电网的一般组成。在此基础上,研究了低压直流微电网的单极故障以及极间故障的故障特征,提出选线方法,对各线路正负极首末端电流差进行Pearson相关系数计算来确定故障线路。然后对所选故障线路正负线路首端的电流量进行广义S变换,计算出其能量和的比值判别故障极性或者极间故障。最后,在PSCAD/EMTDC中搭建出低压直流微电网模型以输出各线路电流数据,并利用Matlab对数据进行仿真。结果表明,所提选线方法直接有效,且耐受过渡电阻的能力较强。

There is limited research on fault line selection methods for low-voltage DC microgrid lines.Thus this paper proposes a fault line selection method based on the Pearson correlation coefficient and generalized S transform.First,the general composition of a low-voltage DC microgrid is introduced.Then the fault characteristics of unipolar and inter-pole faults of low-voltage DC microgrids are studied,and a line selection method is proposed.The Pearson correlation coefficient calculation is performed on the current difference between the first and last ends of two polarities of each line to determine the fault line.Then it does generalized S transform on the current at the head of the positive and negative lines of the selected fault line,and the ratio of energy sum is calculated to identify fault polarity or inter-pole fault.Finally,a low-voltage DC microgrid model is built in PSCAD/EMTDC to output the current data of each line,and then Matlab is used to simulate the data.The results show that the line selection method proposed is direct and effective,and the ability to withstand transition resistance is strong.