基于LMD母线差动保护CT饱和检测方法研究

为解决由于CT饱和而引起的保护不能进行可靠动作的问题,提出一种适用于母线差动保护的基于局部均值分解(LMD)原理的CT饱和检测和故障区判定方法。对流过母差保护的CT暂态电流进行局部均值分解,通过高频分量瞬时频率的突变检测CT的饱和。依据差动电流分解得到的瞬时频率发生突变的间隔时间的不同,对母线发生区内故障、区外故障以及一般转换性故障进行故障识别。用EMTP-ATP软件对所提方法进行了仿真,结果表明该方法能检测CT的饱和,并准确对CT饱和情况下的故障类型进行识别。

A method for CT saturation detection based on LMD in busbar differential protection

In order to solve the problem that protection cannot act reliably caused by CT saturation, this paper puts forward a new method of CT saturation detection and fault area judgement based on local mean decomposition (LMD) principle for bus differential protection. By decomposing the CT transient current, CT saturation can be detected through the mutations of instantaneous frequency of high frequency component. Based on different time interval of mutations of the instantaneous frequency decomposed from differential current, the fault area, such as the internal fault, external fault and the general transform fault can be identified accurately. EMTP-ATP software is used to simulate the application of the method, the result shows that it can detect CT saturation and identify the fault type accurately under the CT saturation.