频域反射法中阻抗变化类型判断技术  

Type Judgement Technology of Impedance Variation in Frequency Domain Reflection Method

作　　者：饶显杰 周凯[1] 黄永禄 李明志 李蓉[1] Rao Xianjie;Zhou Kai;Huang Yonglu;Li Mingzhi;Li Rong(School of Electrical Engineering Sichuan University Chengdu,610065,China)

机构地区：[1]四川大学电气工程学院,成都610065

出　　处：《电工技术学报》2021年第16期3457-3466,共10页Transactions of China Electrotechnical Society

基　　金：国家自然科学基金资助项目(51477106)。

摘　　要：利用行波的反射可以有效地探测电缆的局部缺陷和故障等阻抗异变点,反射波的传播距离和极性可分别用于定位阻抗异变点和判断阻抗异变点的类型。频域反射(FDR)技术是识别电缆中反射波的有效手段之一,但是现有FDR技术仅能计算反射波的传播距离,而不能判断波形极性,因此,该文提出一种FDR的波形极性判断技术。首先阐述FDR中反射波的识别原理,将Hanning自卷积窗的快速傅里叶变换插值算法用于FDR中反射系数谱分析,对FDR测试下限频率和频变波速造成的相位偏差进行修正,得到频率值和修正后的相位值用于计算反射波的传播距离和判断波形极性;然后对单反射波和多反射波的电缆模型进行仿真,检验该技术的可行性;最后在实验室105m长的10kV交联聚乙烯电力电缆上制作阻抗异变点对该方法的准确性进行验证。仿真和实验结果表明,该文所提方法可以有效获取FDR中反射波的传播距离和极性。The reflection of the traveling wave can be used to detect the impedance variation of cable including local defects and faults.The propagation distance and polarity of the reflected wave are respectively used to locate the impedance variation position and judge the type of the impedance variation.Frequency domain reflection(FDR)is one of the effective means to identify the reflected wave in the cable.However,the traditional FDR method can only obtain the propagation distance of the reflected wave,but cannot judge the polarity of the reflected wave.Therefore,this paper presents a polarity judgement technology for the reflected wave in FDR.Firstly,this paper describes the principle of reflected wave identification in FDR,and analyzes the reflection coefficient in FDR by the fast Fourier transform interpolation algorithm of Hanning self-convolution windows.The phase deviations caused by lower limit frequency of FDR and frequency-dependent wave velocity are corrected,and the frequency value and the modified phase value are respectively used to obtain the propagation distance and the polarity of the reflected wave.Then,the cable model of single reflected wave and multiple reflected wave is simulated.Finally,the proposed method is verified by experiments on a 105m 10kV cross-linked polyethylene cable.The results show that the method proposed can effectively obtain the propagation distance and polarity of the reflected wave in FDR.

关 键 词：频域反射 反射波 极性判断 Hanning自卷积窗 相位修正 

分 类 号：TM41[电气工程—电器]