Research On Influence Of Nano Inorganic Fillers Modification On The DC Flashover Characteristics Of Epoxy Resin Composite

Nanocomposite insulation material has excellent electrical properties.How to improve the surface flashover voltage of nanocomposite under DC electric field is a main problem for promoting the UHVDC transmission project in China.At present,the influence of nano-fillers into epoxy resin matrix on the surface charge behavior and surface flashover of composite materials is unclear.Therefore,it is necessary to further study this problem.Firstly,in this paper,boron nitride(BN)and bismuth ferrate(BFO)are used as fillers and at the same time we modified them.BN fluorinated boron nitride nanosheet(F-BNNS)was obtained by hydrothermal method.Bismuth ferrite nanoparticles doped with Ca,Y and Zr elements and BYFO nano wires were prepared by sol-gel method and electrostatic spinning method,respectively.The micromorphology,physicochemical properties of BN filler and the influence of element doping on the structure of BFO cell were studied.The regulation and control of the conductivity and density of BFO packing is realized.Secondly,the DC flashover experiments of boron nitride/epoxy resin,bismuth ferrate/epoxy resin composites under needle electrode have been carried out using surface flashover test platform.The development trend of epoxy resin composites’ flashover voltage with increasing filler concentration has been mastered.Based on SEM,AFM and EDS,the physicochemical properties of composite materials after flashover have been analyzed.The charge was applied to the surface of the composite by corona discharge,and the active capacitance probe was used to test the surface charge behavior of the composite.The surface charge accumulation and surface potential attenuation rate of composite materials are studied,and the main ways to dissipate the surface charge of composite materials have been explored.Finally,based on the surface potential attenuation curves of composite materials,the isothermal potential attenuation calculation was used to obtain the ε’tdV/dt～ET curve,which shows the composite surface trap distribution.The influence of the surface charge accumulation,dissipation level and trap distribution on the flashover voltage of different composite materials has been studied.Combinating these theories and experimental results,the influence of characteristics,dispersion and concentration of fillers on the flashover voltage of composite materials has been analyzed.