基于TFDR波形时域包络线的电缆故障定位技术

Cable Fault Location Technology Based on TFDR Waveform Time-Domain Envelope

传统时域反射法由于其高频成分含量较低,在电缆中的传播过程中信号衰减较大,且无法对信号色散衰减进行补偿,因此仅能够适用于较为严重的缺陷或故障,无法对局部微弱缺陷进行很好地探测,定位准确度较低。基于此,根据参考信号的特性提出了一种基于波形时域包络线的定位技术;先对参考信号及其反射信号在时域上利用希尔伯特变换求取包络,再对包络曲线进行求对数及归一化处理,最后再使用八阶巴特沃斯带通滤波器进行滤波抑制噪声后,分别对50 m及500 m长的电力电缆进行实际测试。结果表明时域包络线技术实现了对电缆缺陷的有效定位,同时结合时域波形变化情况还可对电缆缺陷类型进行判断。

The traditional time-domain reflection method is only applicable to more serious defects or faults because of its low content of high-frequency components,large signal attenuation in the transmission process in the cable,and the inability to compensate for the signal dispersion attenuation.It can not detect local weak defects well,and its positioning accuracy is low.Based on this,according to the characteristics of the reference signal,this paper proposes a positioning technology based on the waveform time-domain envelope.First,the reference signal and its reflected signal are enveloped by Hilbert transform in the time domain,then the envelope curve is logarithmized and normalized,and finally the eighth order Butterworth band-pass filter is used to filter and suppress noise.After that,50 m and 500 m long power cables are actually tested,respectively.The results show that the time-domain envelope technology can effectively locate cable defects.At the same time,the type of cable defect can also be judged according to the change of time domain waveform.