基于距离的互相关算法在电力电缆局部放电定位中的应用

Application of Distance-based Cross-correlation Algorithm in Partial Discharge Location of Power Cable

电力电缆局部放电源定位是找出电缆局部缺陷的有效手段之一。为了解决传统互相关算法的定位结果受采样频率和电缆相速度频变特性影响大的问题,提出了一种基于距离的互相关算法用于电力电缆局放源定位。首先介绍了基于距离的互相关算法的基本原理,然后利用MATLAB建立了局放传播模型验证了该方法的有效性,研究了不同传播距离,不同采样频率和不同信噪比对定位精度的影响。最后利用振荡波测试平台对250 m的10 kV XLPE电力电缆进行局部放电试验,利用不同方法对局放信号进行定位,验证了该方法的优越性。仿真和实测结果表明,由于该互相关算法是直接以距离为自变量,不需要进行时延估计,因此该方法相较于传统的互相关方法具有更高的定位精度。

Locating the partial discharge(PD)source in power cable is one of the effective means to diagnose the local defects of cables.The sampling rate and frequency characteristic of phase velocity have obvious influences on the localization accuracy of traditional cross-correlation algorithm,thus we put forward a distance-based cross-correlation algorithm to locate the partial discharge source in power cables.Firstly,the basic principle of the distance-based cross-correlation algorithm is introduced.Then,the simulations of PD signal are performed with the MATLAB software,and the validity of the algorithm is confirmed.The influences of different propagation distance,sampling rate and signals for noise ratio(SNR)on localization accuracy are studied.Finally,the advantages of the algorithm are showed by partial discharge test experiments,which are performed on a 250 m 10 kV XLPE power cable by using an oscillation wave test system.The simulation and experiment results show that the independent variable of the algorithm proposed in this paper is distance instead of delay time.Compared with traditional cross-correlation algorithm,the algorithm has a better locating result.