基于S变换与时频域反射的电缆缺陷定位方法

Defect location method of cable based on S-transform and time-frequency domain reflectometry

针对电力电缆的局部缺陷定位问题,提出一种基于S变换与时频域反射(time-frequency domain reflectometry,TFDR)的电缆缺陷定位方法。在分析传统电缆缺陷定位方法原理的基础上,利用S变换求取TFDR测试波形的时频分布,并计算时频分布的时频互相关函数,再通过时频互相关函数曲线的局部峰值对电缆局部缺陷的位置进行判断。结果表明:相比于传统的TFDR方法,本文方法的时频分布不存在交叉项干扰,从而消除了时频互相关函数曲线中干扰的局部峰值,且电缆缺陷定位结果的可靠性较高,局部缺陷的检测盲区较小。最后对10 kV交联聚乙烯(XLPE)电缆进行仿真和实测分析,结果显示本文方法可以有效定位电缆的局部缺陷,并且缺陷定位的绝对误差较小。

A new method based on S-transform and time-frequency domain reflection(TFDR) was proposed to locate the local defect of power cable. The principle of traditional cable defect location method was analyzed firstly. The timefrequency distribution of the TFDR test waveform was obtained by S-transform, and the time-frequency cross-correlation function of time-frequency distribution was calculated. Then the location of cable local defect was estimated by the local peak of the time-frequency cross-correlation function curves. The results show that compared with the traditional TFDR methods, there is no cross-term interference problem in the time-frequency distribution for the proposed method, so the local peak of interference in the time-frequency cross-correlation function curve is eliminated, and the reliability of cable defect location results is high and the detection blind area of local defect is small. Finally, the simulation and measurement analysis were carried out on the 10 kV cross-linked polyethylene(XLPE) cable, and the results show that the proposed method can effectively locate the local defect of cable and the absolute error of defect location is small.