基于调频连续波相位敏感特性的电缆局部缺陷检测方法  

Research on Cable Local Defect Detection Method Based on Phase-Sensitive Characteristics of Frequency Modulated Continuous Wave

作　　者：赵书静 詹博博 龚梁涛 王伟[1] 李成榕 孟晓凯 Zhao Shujing;Zhan Bobo;Gong Liangtao;Wang Wei;Li Chengrong;Meng Xiaokai(State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University,Beijing 102206 China;Electric Power Research Institute of State Grid Shanxi Electric Power Company,Taiyuan 030001 China)

机构地区：[1]新能源电力系统国家重点实验室(华北电力大学),北京102206 [2]国网山西省电力公司电力科学研究院,太原030001

出　　处：《电工技术学报》2023年第11期3009-3021,共13页Transactions of China Electrotechnical Society

基　　金：国网山西省电力公司科技项目资助(52053020000V)。

摘　　要：灵敏地检测和定位电缆缺陷对于电缆安全运行具有重要的作用。调频连续波(FMCW)法是一种基于频域反射法的电缆缺陷检测方法,该方法相对于宽频阻抗谱法具有更高的缺陷检测灵敏度及抗干扰能力。该文在现有FMCW方法的基础上,提出利用FMCW的相位敏感特性对电缆缺陷进行检测的方法,提高了现有FMCW方法缺陷检测的灵敏度。首先,结合FMCW相位敏感特性与电缆分布参数模型进行了电缆缺陷检测仿真;然后,在实验室的射频同轴电缆、10 kV交联聚乙烯(XLPE)电缆上模拟不同程度的缺陷并测试,观察缺陷处相位的变化情况,验证了所提方法的有效性。结果表明:相敏-FMCW方法对于射频及10 kV XLPE电缆上模拟的缺陷敏感,不同严重程度的缺陷相位变化量不同,缺陷处对应相位变化的取值区间可为180°。定义缺陷引起的相位、幅值变化量占取值区间的比例为灵敏度,相敏-FMCW方法可以提高现有FMCW方法对该文中所设缺陷检测的灵敏度:对于电缆局部异常温升造成的容性缺陷,当局部温差为37℃时,可将灵敏度由36%提升至71%;对于电阻性、电导性及铜屏蔽破损缺陷,相敏-FMCW方法的灵敏度均优于传统FMCW方法,检测灵敏度提升了7%~62%。Cables play a very important role in the operation of society and are closely related to industrial production and people's lives.Minor defects develop into serious defects that eventually lead to cable failure.In this regard,it is important to be able to detect and locate defects in cables before they occur.Frequency domain reflectometry(FDR)is developing rapidly because it has higher sensitivity than time domain reflectometry(TDR)in terms of cable defects and fault location.In recent years,the broadband impedance spectroscopy(BIS)method based on FDR has made great progress in the field of cable defect location.The BIS method measures the impedance spectrum of the cable through instruments,and analyzes the impedance spectrum to obtain the location spectrum of the cable.However,the BIS method is easily interfered by noise.In order to improve the anti-noise ability of the FDR method,a frequency modulated continuous wave(FMCW)method based on FDR was developed.With the same background noise,FMCW measurements are better and can locate defects further away.FMCW has obtained higher sensitivity than BIS method by measuring the frequency difference,but it is still not sensitive enough for the detection of minor defects in cables that are further developed into serious defects due to the influence of operating environment and other factors.In response to this difficulty,inspired by the use of phase characteristics to improve the distance resolution of the FMCW method in the process of high-precision liquid level measurement,we propose a phase-sensitive-FMCW method to improve the sensitivity of the FMCW method to the measurement of cable defect state changes.First,based on the principle of FMCW cable defect location,the basis for using FMCW phase characteristics to detect defects is proposed:the phase of the mixing signal is affected by the chirp signal,and the phase signal is double modulated by both amplitude and phase.When the reflected signal changes,the phase also changes.Even if the defect position remains unchanged,

关 键 词：相位敏感 调频连续波(FMCW) 同轴电缆 缺陷检测 

分 类 号：TM247[一般工业技术—材料科学与工程]