一种考虑时域特征的单端行波固有频率测距方法

行波固有频率主成分的精确提取是影响基于行波固有频率测距方法测距精度的主要原因.在考虑行波时频特征的基础上提出一种新的基于行波固有频率的故障测距方法:首先利用小波变换的尺度图得到固有频率主成分的粗略值,并在此频率值的邻域内对信号的时域特征进行分析,提取信号的时域周期,从而得到更为准确的频率值,并据此频率值及系统参数计算故障距离.EMTDC 仿真实验结果表明:该方法能在一定程度上提高故障测距的精度,且不受故障距离、故障电阻、故障初相角和故障类型的影响,能很好地适应不同的噪声水平

Single Terminal Fault Location by Natural Frequencies of Travelling Wave Considering Its Time-Domain Characteristics

Whether the principal component of fault travelling wave’s natural frequencies could be accurately extracted or not greatly influences the fault location accuracy of fault location method based on natural frequencies of travelling wave.On the basis of considering travelling wave’s time-and frequency-characteristics,a new fault location method based on natural frequencies of travelling wave is proposed.Firstly,utilizing the scalogram of wavelet transform,the approximate values of the principal component of natural frequencies are obtained,and within the neighborhood of these frequenciy values the time-domain characteristics of the signal are analyzed;then the time-domain periods of the signal are extracted to achieve more accurate frequency values and according to these frequency values and system paramters the fault distance is calculated.Simulation experiment by EMTDC show that the proposed method can improve the accuracy of fault location to a certain extent,and the fault location result is not affected by fault distance,fault impedance,initial phase angle by which the fault occurred and fault types,and can work well at different noise levels.