用ILMD多尺度时频熵识别直流牵引网振荡电流与故障电流  

Identification Approach of Oscillation Current and Fault Current in DC Traction Network Based on ILMD Multi-Scale Time-Frequency Entropy

作　　者：杨洪耕[1] 冷月[1] 王智琦[1] YANG Honggeng;LENG Yue;WANG Zhiqi(School of Electrical Engineering and Information,Sichuan University,Chengdu 610065,China)

机构地区：[1]四川大学电气信息学院

出　　处：《高电压技术》2018年第8期2457-2463,共7页High Voltage Engineering

基　　金：国家自然科学基金(51477105)~~

摘　　要：针对城市轨道交通直流牵引网的振荡电流容易引起继电保护系统频繁误动的问题,提出了一种基于改进局部均值分解的多尺度时频熵识别直流牵引网振荡电流与短路故障电流方法。利用改进局部均值分解法分析直流牵引网的馈线电流信号,获得其时频分布;将信息熵理论引入时频分布,对时频平面进行频段划分,计算各频段的时频熵,求出时频平面的整体多尺度时频熵;定量描述馈线电流信号的能量在时频平面分布的均匀性,均匀性的不同可以反应直流牵引网运行状态的差别,从而可通过多尺度时频熵的大小区分直流牵引网的振荡电流与短路故障电流。算例分析验证了该方法的有效性。Aiming at frequent malfunctions of the relay protection system caused by the oscillation current in DC traction network of urban rail transit, we propose a method for identifying the oscillation current and short-circuit fault current in DC traction network based on improved local mean decomposition（ILMD） and multi-scale time-frequency entropy. Firstly, the ILMD method is used to analyze the feeder current signal in DC traction network so that the time-frequency distribution of the feeder current signal can be obtained. Secondly, the Shannon entropy theory is introduced into the time-frequency distribution, and the time-frequency plane is divided into some frequency channels. Then the time-frequency entropy of each frequency channel is figured out. Finally, the overall multi-scale time-frequency entropy of the time-frequency plane is acquired, which can be used to quantitatively express the uniformity of the distribution of the feeder current signal＇s energy in the plane. Differences in uniformity can indicate differences among operating states of DC traction network, which makes it possible to distinguish the oscillation current and short-circuit fault current in DC traction network by means of multi-scale time-frequency entropy. On the basis of simulation analysis and field data calculation, availability of the suggested approach is certified.

关 键 词：直流牵引网 振荡电流 短路故障电流 改进局部均值分解 多尺度时频熵 

分 类 号：U223[交通运输工程—道路与铁道工程]