基于BOTDA/R的在运光纤复合架空地线光缆应变监测对比分析

Comparative Analysis of Strain Monitoring of the Installed Optical Fiber Composite Overhead Ground Wire Using BOTDA/R

光纤复合架空地线(OPGW)故障频发的原因与光缆局部受到的应力有直接关系,为了实现对OPGW光缆的在线应变监测,搭建了长距离布里渊光时域分析(BOTDA)和布里渊光时域反射(BOTDR)系统,并对重覆冰区域运行年限超过15年的在运95.14 km OPGW进行了应变检测和分析。通过对同一段光缆的对比测量,结果表明:BOTDA系统具有更长的测量距离、更高的空间分辨率与更高的测量精度,能准确辨别引下线并识别零应变参考点,可以实现温度和应变信息的准确分离。在两个站点的距离超过BOTDA系统的测量量程时,可以使用BOTDR系统从光缆两端分别测量以覆盖全部光缆。同时,BOTDR系统展现出单端测量的优势,在断纤故障发生时,BOTDR系统可不影响断点之前的线路测量。在同一条OPGW光缆线路上通过多维度的对比,分析了两种技术在OPGW光缆监测中的优劣势,为分布式光纤传感技术在电力系统中的应用提供参考。

The frequent failure of the optical fiber composite overhead ground wire(OPGW)can be attributed to the local stress on the optical cable.Herein,the long-distance Brillouin optical time-domain analysis(BOTDA)and Brillouin optical time-domain reflectometry(BOTDR)sensing systems were established to achieve online monitoring of the strain with respect to the OPGW optical cable.Further,strain detection and analysis were conducted in case of a 95.14-km OPGW installed for more than 15 years in the heavily iced disaster area.The measurement distance,spatial resolution,and measurement accuracy of the BOTDA sensing system are greater than those of the BOTDR sensing system based on the comparative measurement results obtained using the same optical cable.In addition,the down conductor and zero-strain reference point can be accurately identified to achieve accurate separation of temperature and strain information.When the distance between two stations exceeds the BOTDA measurement range,the whole cable can be evaluated from two ends of the fiber cable using the BOTDR sensing system.The BOTDR sensing system exhibits single-ended measurement such that this system can continue performing the line measurement after a fiber break before the break point.In this study,the advantages and disadvantages of the BOTDA and BOTDR sensing systems in OPGW optical cable monitoring are analyzed for the first time by performing a multidimensional comparison using the same OPGW optical cable.Furthermore,this study provides a reference with respect to the application of the distributed optical fiber sensing technology in power systems.