The Research On Power Cable Fault Point Position Based On Optical Fiber Sensing Technology

China’s national economic development is inseparable from the power industry. Powercables with distribution and optimization help beautify the urban layout of factories. Powercables have a lot of advantages like safety, reliability and so on. Power cables are widelyapplied in our country. Development of national economy needs safety and reliability powersystem. If the power system appears an accident, the national economy will be a huge loss,and causes the national political and people’s lives seriously. When the transmission linefailure, need to quickly identify the point of failure. On the transmission line fault detection,requires a lot of time and put a lot of resources, but due to human causes, not exactlyproduce false positives,huge economic losses. Power system to ensure high efficiency,lowcost, high security required for the operation of the power system transmission lines foraccurate fault location. In this context, power cable fault location of R&D has a realeconomic effect, is the power system more secure.This paper based on wave reflection method, the optical fiber vibration sensortechnology and Rayleigh scattering theory are applied in the aspects of the cable fault location.Advantage is that the cable is a mechanical breakdown wave vibration wave which is notaffected by electromagnetic interference. Through theoretical analysis showed that: in cabletunnels, the vibration wave of cable-stand, spread along the cable trench wall. Close to thecable trench wall conduction fiber is able to detect such waves.By Linear damped free vibration model obtains Exponential decay equationy ke x.By Dimensional analysis model obtains Negative power attenuation formula y kx.Vibration wave equations show that the propagation distance increases, the amplitude of thevibration waves are attenuated. Model tests show that with the propagation distanceincreases, the amplitude of the vibration waves is attenuated. In shock loads, vibrationamplitude attenuation along the propagation direction of the exponential decay law, thenegative exponentiation decay fitting. Among them, to use negative power function todescribe is better. The speed of the shock wave attenuation is relevant with sand compaction.When the degree of compaction is92-94%, the decay is the slowest. But the cover cable andfiber sand compaction can’t be so high, so the degree of compaction of sand should be inensuring the cable and fiber from damage under the premise of sand compaction as high aspossible. Through field trials on the cable duct, wearing three kinds of pipes and laying of cabletunnel mode vibration signal cable fault testing. In experiment, cable duct in an openenvironment, at the beginning the sensing fiber is placed next to the cable, the dischargepoint is in the upper right of the sensing fiber, the sensor fiber cable undetectable dischargeshock wave. When the cable and the sensor fiber are filled with sand, the sensor fiber cablecan detected the vibration wave by the discharge generated. Then the object compacts, theeffect is more obvious. The cable tunnel mode, the sensing fiber can acquire basic dischargecable fault vibration generated waves. From the test, illustrates that use of fiber Rayleighscattering theory for power cable fault location is feasible.