Research On Surface Discharge Characteristics Of Macro Interface Between Solid Epoxy Resin Insulation And Inorganic Powder

Gas insulated metal enclosed transmission line（GIL）is commonly used in high-voltage power transmission,because of its advantages of large transmission capacity,low loss and high reliability.However,a lot of problems existing in environmental protection and economy of traditional GIL which use SF₆ as insulating medium.For this reason,the concept of inorganic powder insulated transmission line（IPIL）was proposed.The idea is to replace SF₆ with inorganic powder materials which are more economic and environmentally friendly.At the same time,the physical and chemical properties of inorganic powder material are more stable and its properties of insulation and thermal conductivity are very excellent.The feasibility of inorganic powder insulated transmission lines needs to be discussed.Therefore,it is necessary to research the surface discharge characteristics of the interface between inorganic powder and epoxy resin,and preliminarily explore the advantages and disadvantages of inorganic powder as insulation filling medium.In this thesis,a surface discharge test system was designed and built,and the surface discharge characteristics of the interface between inorganic powder and epoxy resin were studied under the conditions of different types,different particle sizes,different stacking states,different surface discharge time intervals and different compounding ratios under DC voltage.The results show that inorganic powder can improve the insulation level of the interface compared with air,but with the increase of the surface discharge voltage,the epoxy resin surface will be severely ablated,and the insulation recovery of the interface will decrease;The surface discharge voltage at the interface of magnesium oxide and epoxy resin,the interface of silicon dioxide and epoxy resin and the interface of kaolin and epoxy resin increased with the increase of particle size,while the surface discharge voltage at the interface of alumina and epoxy resin and the interface of boron nitride and epoxy resin decreased with the increase of particle size;Compared with other kinds of inorganic powders,the insulation properties of the interface between magnesium oxide and epoxy resin and the interface between alumina and epoxy resin are better;The inorganic powders are stacked more closely after the external pressure is applied,which significantly improves the surface discharge voltage at the interface between inorganic powders and epoxy resin,but further sacrifices the insulation recovery of the interface.Under the external pressure,the interface between silica and epoxy resin,the interface between kaolin and epoxy resin,and the interface between boron nitride and epoxy resin are easy to lose the insulation performance after the surface discharge;Prolonging the time interval of surface discharge can improve the insulation level and insulation recovery of the interface between inorganic powder and epoxy resin;The composite inorganic powder can effectively improve the insulation performance of the interface between inorganic powder and epoxy resin.