Research On The Strain State Detection Of OPGW Fiber Optic Cable In Operation In The Power Grid Based On Long-Distance BOTDR

Optical Fiber Composite Overhead Ground Wire(OPGW)is the "backbone" for information convergence and exchange in the power communication network,carrying the core business of the power grid production and operation and maintenance departments.As the operation of fiber optic cable increases,it will inevitably have faults and hidden problems,therefore,the operation of fiber optic cable needs to be inspected regularly.Brillouin Optical Time-Domain Reflectometer(BOTDR)technology is an efficient,scientific and emerging technology that can be used for structural health inspection of large buildings,and has many advantages over traditional inspection technologies,and has been widely used in engineering projects such as bridges and oil and gas pipelines safety inspection.In this paper,we apply the long-range BOTDR technology to the OPGW fiber optic cable inspection,and analyze the influence of each typical influencing factor on the fiber optic cable strain by collecting and processing the frequency shift data of OPGW fiber optic cable Brillouin,and then correlate the influencing factors with the fiber optic cable strain,aiming to achieve the advance interference of the factors affecting the fiber optic cable strain and ensure the influence of the influencing factors to be minimized,which is important to ensure the safe operation of the power transmission system.It is of great significance to ensure the safe operation of the power transmission system.The specific research contents are as follows:First,the principle of Brillouin scattering is introduced,the relationship between Brillouin frequency shift and temperature and strain is described,and then the operation scheme of the BOTDR system is elaborated.Secondly,based on the distributed strain measurement results of the long-range BOTDR system on the OPGW fiber optic cable in operation,the effect of creep,meteorological triple elements,stall distance and height difference,as well as the rigidity of the fiber optic cable on the strain of the fiber optic cable is specifically studied.The results of the study show that creep affects the arc sag length of the fiber optic cable.The temperature of the three meteorological elements will make the fiber optic cable thermal expansion and contraction,resulting in strain;ice increases the specific load on the fiber optic cable,resulting in permanent strain on the cable;wind is prone to cause the fiber optic cable to vibrate at high altitude.When the line between the lowest point of the horizontal stress and fiber optic cable is subject to a certain load,the greater the difference in height of the line,the greater the stress on the point,usually the maximum stress at the high hanging point;the greater the file distance,the greater the stress on the fiber optic cable.The actual in the transport line,the stiffness will cause concentrated strain in some areas of the line,and over time,it will also cause the fracture of the fiber.Finally,based on the distributed strain test data of a large number of OPGW fiber optic cable lines in operation,a correlation analysis was conducted with the data mining hotspot algorithm on the operating life of fiber optic cable,the terrain it is located in,the file distance and the height difference,and the specific connection between the stress strain and the key influencing factors was obtained.The final analysis results show that in the operation life of 13-15 years,the proportion of strains generated by fiber optic cables with towers erected in mountainous terrain is39.604%,among which the proportion of strains generated by fiber optic cables with a file distance less than or equal to 538 m is 45.324%;the proportion of strains generated by fiber optic cables with a file distance between 266 m and 538 m is 47%;the proportion of strains generated by fiber optic cables with a file distance between266 m and 538 m and The percentage of strain in the cable with a height difference less than or equal to 21 m is 48.421%,and the percentage of strain in the cable increases gradually.Therefore,based on the above results,this paper concludes that the longer the operating life,the higher the terrain,and the greater the pitch and height difference,the greater the possibility of stress strain on the line,excluding the interference of external factors.