Fault Location System Of GIL Based On ?-OTDR And Optical Interference

Take the advantages of less harm to environment,smaller land occupation and higher running stability,gas insulated transmission lines(GIL)is developing rapidly.However,since the GIL line can be over 1km in length,once the flashover fault due to the insulation defect occurs during the operation of the GIL,the existing GIL fault detection and fault location technology is difficult to implement and the positioning cost is high.To solve the problems mentioned above,especially the scale of GIL is getting much further expand,in this paper,an optical fiber distributed sensing system combined with phase-sensitive optical time-domain reflectometry(?-OTDR)and Michelson interferometry is adopted to monitor and locate the abnormal vibration of GIL caused by flashover or breakdown.Firstly,the band characteristics of vibration signal caused by GIL discharge fault were analyzed.The working principle of(?-OTDR and optical interference technology was studied,and the advantages and disadvantages of the two techniques were compared and analyzed.Based on this,combined with WDM technology,a distributed optical fiber sensing system based on ?-OTDR technology and optical interference technology is set up on a single optical path topology,to meet the requirements of continuous light and pulsed light of different wavelengths transferring on the same sensing fiber.In theory,the feasibility of measuring the position information and the frequency information of the external broadband vibration can be theoretically described.Secondly,the measurement of external vibration signals based on ?-OTDR technology and optical interference technology are respectively carried out.On this basis,the ?-OTDR technology and the distributed optical fiber sensing system multiplexed by optical interference technology are further established,and the algorithm research is carried out.Realize the optical signal demodulation and fault location.PZT simulation of stable vibration signals and off-lead simulation of transient vibration signals were carried out.Through(p-OTDR technology,the system can locate the vibration signals with the positioning accuracy up to?2.8m.Through the interference technique,the system can realize the vibration signals frequency domain information analysis,detection band better than 1kHz?150kHz.So the system can achieve two kinds of distributed optical fiber sensing technology and achieve broadband vibration signal location and frequency information simultaneously.Finally,in order to test the performance of distributed optical fiber sensing system for fault location of GIL,this paper builds a GIL flashover fault location simulation test platform based on GIS,and adopts the method of embedded metal particles as insulation defect in GIS insulator.The detection of vibration signal caused by network failure has been used to detect the fault vibration signals by ?-OTDR technology and optical interference technology.Fault localization and frequency domain information analysis have been carried out by algorithm.The experimental results show that the detection distance of the distributed optical fiber sensing system can reach 1.1km and the positioning accuracy of the vibration signal can reach?15m,and frequency band of the fault induced vibration signal is 1.97kHz?9.27kHz.