Location And Quantitative Detection On Single Glaze Icing Of Composite Insulator With Embedded Fiber Bragg Grating

Due to its excellent anti-contaminated performance,low weight,high mechanical strength,composite insulators have been widely used in power grids.However,with the rapid development of power grids,transmission lines have to pass through high altitude,high humidity,and icing/snowing areas,which causes ice accretion on sheds of composite insulators.Especially,glaze icing has the characteristics of high hardness and strong adhesion causing a high probability of ice flashover on insulators,so it is the most dangerous icing type for power grid security.There are several traditional monitoring methods for ice-covered insulators,such as ultraviolet imaging,leakage current,video camera,and unmanned aerial vehicle(UAV).However,some deficiencies still exist in the conventional detection methods,such as the cameras are easily blocked,the UAV can not take off on rainy and snowy days,and the power supply is unstable.Therefore,the researches on intelligent sensing icing conditions of insulators are conducive to the prevention of transmission line icing disasters,which are important to the construction of smart grid and Ubiquitous Electric Internet of Things.Fiber Bragg Grating(FBG)has many advantages,including insulation,anti-electromagnetic interference,and passive sensors.Moreover,optical fiber signal lines and FBG sensors are suitable to embed into the long stick structure of composite insulator.The composite insulator with embedded FBG(CIEF)can form large signal transduction and distributed sensing networks for monitoring operating conditions.In this dissertation,the location and quantitative detection on single glaze icing of CIEF was researched based on the FBG sensing principle.The main research contents are as follows:(1).Optical fibers with FBGs were embedded into the housing-core interface,and the interface property was verified.First,three optical fibers with FBGs were embedded in the housing-core interface of a composite insulator using epoxy resin(ER)or room temperature vulcanized silicone rubber(RTV).Then,the composite insulators with FBG(CIEF)were produced,called CIEF-ER and CIEF-RTV.Finally,the modified water-diffusion test,leakage current measurement,and scanning electron microscope(SEM)test were performed for analyzing interface properties by interface leakage current and microscopic images.(2).Discrimination measurement of temperature and glaze icing load on insulator.For solving the cross-sensitivity to temperature and strain of FBG,the ceramic package was used to measure temperature and glaze icing load discriminately.Besides,the implanted and non-implanted FBG temperature compensation sensors were proposed.Then,the temperature calibration experiments of CIEF were performed for researching the relationship between temperature and wavelength shift of FBG.Finally,the influence of radial force and axial force on the wavelength of the FBG temperature compensation sensor was analyzed,and the temperature compensation method for CIEF was proposed.(3).Location and quantitative detection method on single glaze icing load of CIEF.First,the simulated glaze load experiments were performed.Then,the influence of single glaze load and multiple glaze loads on the wavelength shifts of FBGs on the same shed,and the influence of single glaze load on the wavelength shifts of FBGs on the adjacent and spaced multiple sheds were researched.Besides,the glaze load sensitivities of FBG were obtained.Finally,based on the weighted centroid positioning principle,the location and quantitative detection on single glaze load was proposed and verified.(4).The glaze load strain simulation and mechanical analytical model of FBG strain transfer were researched.First,a three-dimensional finite element simulation model of CIEF was established,and the wavelength shift of FBG in a non-uniform strain field was calculated by the transfer matrix method.Then,the mechanical analytical model of FBG strain transfer was established,and the strain transfer coefficient from sheath to FBG was calculated.In addition,the simulation was performed for studying the influence of single glaze load and multiple glaze loads on the wavelength shifts of FBGs on the same shed,and the influence of single glaze load on the wavelength shifts of FBGs on the adjacent and spaced multiple sheds.The results provide a theoretical basis for the proposed detection method.(5).The location and quantitative detection method on single glaze icing load was researched by artificial glaze icing test.First,glaze icing was accretion on a CIEF in the low-temperature artificial climate chamber,and the Savitzky-Golay filtering method was used to reduce the noise.Then,the influences of single glaze load on the wavelength shifts of FBGs on the same shed,adjacent and spaced multiple sheds were analyzed.Besides,The location and quantitative detection method was used to detect the location and load of glaze in artificial glaze icing test.The results were compared with the simulated glaze load experiments in Chapter Four,which verified the accuracy of the proposed method.The research results in this dissertation provided a new idea and good reference values for passive sensing icing conditions of the insulator.