频域反射法阻抗匹配技术及其在电缆衰减补偿与相速度计算中的应用  

Impedance Matching Technology for Frequency Domain Reflectometry and Its Application in Cable Attenuation Compensation and Phase Velocity Calculation

作　　者：谢敏 李烨 俞骏[1] 钱磊[1] 杨东兴[1] 孙庆明 周凯[2] XIE Min;LI Ye;YU Jun;QIAN Lei;YANG Dongxing;SUN Qingming;ZHOU Kai(State Grid Wuxi Power Supply Company,Wuxi 214000,Jiangsu Province,China;School of Electrical Engineering,Sichuan University,Chengdu 610065,Sichuan Province,China)

机构地区：[1]国家电网无锡供电公司,江苏省无锡市214000 [2]四川大学电气工程学院,四川省成都市610065

出　　处：《电网技术》2024年第4期1762-1769,共8页Power System Technology

基　　金：国家自然科学基金项目(52277156);四川省科学技术厅青年科技创新团队项目(2020JDTD0013)。

摘　　要：频域反射法(frequency domain reflectometry,FDR)是诊断电缆绝缘状态的有效方法。针对现场FDR测试中存在的首端阻抗不匹配问题,该文提出了一种有效的FDR首端阻抗匹配技术。该文通过引入可变串联阻抗模型,结合估计得到的电缆特性阻抗,有效解决了FDR现场测试中分叉引线对测试结果的影响。首先,通过搭建电缆模型,结合行波的多次折反射原理推导了电缆首端的反射系数,阐述了信号在电缆内部的传输过程。然后,给出了电缆首端存在分叉引线时的首端阻抗匹配技术。最后,在同轴电缆及10 kV电力电缆上开展了电缆首端阻抗匹配试验,验证了该方法的有效性和准确性。结果表明:该方法可有效解决现场测试中存在的电缆首端阻抗不匹配问题,并且利用首端阻抗匹配处理后得到的数据,亦可实现电缆衰减的有效补偿及电缆相速度的准确计算。Frequency domain reflectometry(FDR)is an effective method for the cable insulation condition diagnosis.Focusing on the problem of the impedance mismatching in the field FDR detection,this paper presents an effective FDR impedance matching technology.By introducing the variable series impedance model,combined with the estimated characteristic impedance,the influence of the bifurcated leads on the field FDR test results is effectively removed.Firstly,the cable model was established,and by the use of the principle of multiple refraction and reflection of the traveling waves,the reflection coefficient at the head of cable was deduced,which explained the signal transmission process in the cable.Then,this paper presented an impedance matching method at the head of the cable when the bifurcated lead was existed.Finally,the impedance matching tests were performed on the coaxial cable and the 10 kV power cable,and the validity and accuracy of the method in this paper were verified.The results show that the proposed method is able to effectively solve the problem of impedance mismatching at the head of the cable in the field FDR detection.By using the matched data,the attenuation of the cable is able to be compensated effectively,and the phase velocity of cable be calculated accurately.

关 键 词：电缆 频域反射法 阻抗匹配 衰减补偿 相速度计算 

分 类 号：TM721[电气工程—电力系统及自动化]