Study On Improving Electrical Properties Of Epoxy Resin Based On Functional Gradient Modification Of Plasma Surface

Epoxy resin is often used as an insulating support for electrical equipment such as gas-insulated transmission lines due to its excellent mechanical properties and electrical properties,but under the action of DC high voltage,it is easier to accumulate at the triple junction of epoxy resin,insulating gas and metal conductor.A large amount of electric charge leads to electric field distortion,which reduces the performance of insulating equipment,brings a huge threat to the safe operation of electrical equipment,and limits the promotion of HVDC projects.At present,conventional surface modification techniques often treat the surface of insulating materials uniformly,but the electric field environment where insulators are located is not uniformly distributed under actual working conditions,and uniform surface modification methods are difficult to achieve optimal results.In this paper,the surface functional gradient modification of epoxy resin is carried out by atmospheric pressure plasma jet technology,and a better gradient modification scheme is explored,to achieve the purpose of improving the insulation properties of the material.First,the atmospheric pressure plasma jet surface functional gradient modification platform,the surface flashover test platform,the surface charge dynamic scanning platform and the physicochemical properties test platform were built.In order to explore the effect of surface functional gradient modification on the electrical properties of epoxy resin,the surface of epoxy resin was modified by plasma gradient deposition of Si O_X film with ethyl orthosilicate as the precursor,combined with the physical and chemical properties of the surface before and after modification.And the electrical performance test,as well as,the modification mechanism were explained.The surface functional gradient deposition of Si O_X film improves the surface conductivity of the four regions of the epoxy resin to different degrees.The flashover voltage along the surface of the sample can reach up to22.57k V,which is 30.16%higher than that of the untreated sample.Secondly,the effect of plasma surface functional gradient fluorination modification on the electrical properties of epoxy resin was studied,and F element modified surface functional gradient materials were prepared using carbon tetrafluoride as the precursor.The research shows that the surface functional gradient fluorination modification can improve the surface dielectric strength of epoxy resin,and the flashover voltage along the surface can reach up to 22.12k V,which is 27.57%higher than that of the untreated sample.Finally,the influence of the surface conductivity gradient distribution on the electric field distribution on the epoxy resin surface is explored.The surface conductance gradient optimization model was built by COMSOL simulation software,and a fast estimation method of surface electric field based on convolutional neural network was proposed.Then,the surface conductance parameters of epoxy resin were optimized based on IPSO and Adam algorithm.The results show that the optimal surface conductance gradient distribution can reduce the maximum electric field strength on the EP surface by 64.75%compared with the untreated samples.The surface optimal conductance gradient modification scheme guided by the simulation results reduces the surface charge accumulation of the epoxy resin,and the flashover voltage along the surface is increased by 34.20%compared with the untreated sample,which effectively improves the insulation performance of the material.In summary,the plasma surface functional gradient modification method proposed in this paper can effectively improve the surface insulation performance of epoxy resin,and provides a scientific basis and a possible solution for solving the insulation problem of high-voltage DC equipment.