Research On FBG Fault Detection Method In Buried Cable

With the rapid development of the smart grid,the transmission and distribution network of large and medium cities in our country are upgrading and upgrading.Buried cable is replacing the traditional overhead transmission network.Buried cables are susceptible to environmental impact of land subsidence and corrosion.When the cable fault occurs,people usually dug up the whole line to determine the location of the point of failure,which not only delay fault repair time,but also consumes a lot of manpower.Fiber Bragg Grating(FBG)is sensitive to temperature,strain and other physical quantities,and has a good linear relationship with the central wave.At the same time,it has good performance of anti electromagnetic interference,high sensitivity and can be easily arranged in the buried cable into a sensor network for remote online monitoring.In this paper,a FBG fault monitoring system for underground cables is designed.The system can monitor buried cables and improve the reliability of cable power supply.Based on the basic theory of FBG,this paper probes into the basic structure and sensing principle of FBG.The relationship between the central wavelength of FBG and the external temperature and strain is analyzed qualitatively.The commonly used and relatively mature FBG demodulation method is studied,and the demodulation method based on tunable fiber F-P filter is selected according to the actual demand of the buried cable.The components of the system and the characteristic parameters of the components are analyzed in detail.The working principle and the characteristic parameters of the tunable fiber F-P filter are studied,and the driving signal amplifying circuit is designed for the F-P filter.The relationship between the scanning voltage and the transmission wavelength of tunable fiber F-P filter is obtained by experiments.For the overall design of the system software,this paper focuses on the design of the data acquisition and signal processing methods,and compares the serial processing and parallel processing methods.At the same time,it gives some core LabVIEW program block diagram.Finally,according to the fault characteristics of the buried cable,a special FBG temperature and strain sensor is designed,and the sensitivity of the sensor to the temperature and strain is tested.