基于时频分量相关分析的高压电缆双端行波测距

高压电缆行波测距需解决2个关键问题:确定行波到达时刻和选取行波波速。由于线路存在损耗且参数随频率变化,导致行波在传播过程中存在波形畸变,不易确定行波到达时刻;另外由于不同频段的波速不同,因此不易选取一个固定的行波波速。针对以上问题,利用正交小波的频段剖分功能和适合表征暂态信号的特点,将暂态行波信号分解成多个频段内的时频分量信号。在各个频段,线路的衰减系数和波速都可近似为常数,因此各频段两侧的时频分量波形相似。用相关分析方法在各个频段确定两侧行波时频分量的时间差,结合各个频段内的波速,即可得出精确的双端行波故障测距结果。用EMTDC仿真对该方法进行了实验验证。

Double-terminal traveling wave fault location for HV cable based on time-freouencv component correlation analysis

There are two difficulties in traveling wave fault location of high voltage power cable: the detection of traveling wave arriving time and the selection of traveling wave velocity.Because of the line loss and frequency-dependent line parameters,the traveling wave distorts during transmission,making the detection of wave-front very difficuh;as the traveling wave changes from band to band,it is impossible to use one velocity for all frequencies.A new traveling wave location method is presented,which decomposes the transient traveling wave signal to time-frequency components of several frequency zones through orthogonal wavelet transform,and the attenuation coefficient and wave velocity of each zone are approximately regarded as constants.The waveforms of the time-frequency components at both terminals of each zone are similar and the correlation analysis is carried out to calculate their time difference.Together with the constant velocity of frequency region,the accurate fault location is figured out.The proposed method is proved by EMTDC simulation.