The Influence Of Antioxidant And Graphite Nanoplatelets On DC Dielectric Properties Of XLPE

Direct current(DC)transmission has the advantages of large transmission capacity,long transmission distance,saving land resources,small system security,and plays an increasingly important role in the power grid.As an indispensable part of DC transmission system,cross-linked polyethylene(XLPE)insulated high voltage direct current(HVDC)cables gain a wide attention attention in recent years and get continuous development.Although XLPE insulation materials have excellent performance in the dielectric and mechanical properties,XLPE insulated DC cables are still difficult to produce and use in a large scale due to space charge accumulation,the electric field distortion under the temperature gradient.Therefore,research on the preparation of XLPE insulating materials with excellent properties not only has significant scientific significance,but also produces good economic and social benefits.In this paper,antioxidant/XLPE and graphite nanoplatelets(GNPs)/antioxidant/XLPE composites were prepared by melt blending method.The DC breakdown strength,conductivity and space charge distribution of the composites were tested,the effect of different antioxidants on DC dielectric properties of XLPE was studied,and the effects of type and content of GNPs on DC dielectric properties of antioxidant/XLPE composites were further investigated.The results indicate that the addition of antioxidants reduced the breakdown strength of XLPE,and the breakdown strength decreased obviously with the increase of temperature.After adding GNPs,DC breakdown strength of the antioxidant/XLPE composites was further reduced,but the conductivity of the composites reduced,which reduced the probability of thermal breakdown at high temperature and the effect of temperature on DC breakdown strength of composites.Adding antioxidant would increase the amount of space charge in XLPE,but the addition of a certain amount of GNPs would improve the distribution of space charge in antioxidant/XLPE composites and suppress the accumulation of space charge in the composites.