基于VMD-SMMG变换的微弱行波双端测距研究

Research on Weak Traveling Wave Location Based on VMD-SMMG Transform

针对高压输电网特殊故障情况下行波信号能量微弱导致测距存在死区以及定位精度不高的问题,在考虑线路弧垂影响的前提下,提出了一种基于变分模态分解(VMD)和级联多分辨形态梯度变换(SMMG)相结合的方法,实现微弱行波的双端测距。首先,将微弱行波信号进行VMD分解得到多个固有模态函数;然后,利用SMMG变换对微弱信号的累积放大特性对分解得到的第一个模态分量进行突变特征检测,完成对微弱初始行波波头时间的精确标定;最后,采用多因素影响的线路长度参数修正提高故障测距精度。PSCAD/EMTDC仿真和实例验证表明,在发生高阻接地或电压过零点接地时,该方法对微弱行波波头突变特征具有良好的检测效果,能够保证较高的故障定位精度。

In view of the dead zone and location accuracy of transient traveling wave in the case of special conditions of high voltage transmission network,considering the effect of line sag,a method based on variational mode decomposition(VMD)and serial multi-resolution morphology gradient(SMMG)is proposed to realize double terminal location of weak traveling wave.Firstly,using VMD on the component of fault current line to get multiple intrinsic mode function(IMF).Then the mutation characteristics of the first IMF is received with the help of SMMG transform to determine the arriving time of the weak traveling wave head.Finally,the parameter correction of line length is adopted to improve fault location accuracy.The method considers the influences of various complex unfavorable factors on location results,especially for high-impedance grounding or voltage zerocrossing grounding.Abundant EMTDC simulation results verify correctness and effectiveness of the proposed method.