针对传统电缆故障定位法受波速和噪声影响导致的波头识别不准确及故障定位精度差问题,提出一种基于小波降噪、经验小波变换(empirical wavelet transform,EWT)和Teager能量算子(Teager energy operator,TEO)的电缆故障定位方法.首先,利用改进的双端行波法消除波速对测距偏差的影响.然后,采用小波降噪法对采集的故障信号进行去噪.进一步应用EWT方法对降噪信号进行分解,提取降噪信号的高频分量.在此基础上,通过TEO能量曲线变化确定首端波头及近端反射波的到达时间,从而计算出电缆故障点到检测位置的距离.仿真结果表明,基于小波降噪和EWT-TEO的电缆故障定位方法对不同信噪比和故障电阻都具有良好的适应性和可靠性,能实现精确的电缆故障定位.
Cable Fault Location Method Based on Wavelet Denoising and EWT-TEO
In view of the issues of inaccurate wave head identification and low precision of fault location caused by the influence of wave velocity and noise in traditional cable fault location method,a cable fault location method based on wavelet denoising,empirical wavelet transform(EWT),and Teager energy operator(TEO)is proposed.Firstly,an improved double-ended traveling wave method is utilized for reducing the velocity effect of wave on distance measurement deviation.Then,a wavelet denoising approach is employed for excluding noise of the detected fault signal.Moreover,the EWT method is employed to decompose the denoised signal and extract high-frequency components.On this basis,the TEO energy curve variation is used to determine the arrival time of the first wave head and the nearest-end reflection wave.Therefore,the distance from the fault point to the tested location can be calculated.Simulation results indicate that the proposed cable fault location method based on wavelet denoising and EWT-TEO exhibits excellent flexibility as well as high reliability for different signal-to-noise ratios and fault resistances.It can achieve accurate cable fault localization.
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