Investigation On The Electrical Insulation Properties Of Polyethylene Based Nanocompositedielectrics

With the rapid development of UHV grid and HVDC technology in recent years,the application of HVDC cables is becoming more and more widely.However,the problem of space charge in polymers is an important constraint to the development of HVDC cables.To solve the problem of space charge in HVDC cables,it is urgent to modify traditional insulating materials or develop new high-performance insulating materials.Polymer based nano composite dielectrics gradually become a hotspot in the field of electrical insulation research.In this paper,polyethylene based BN nanocomposites were designed and prepared,and the microstructure,breakdown and dielectric properties,electrical conductivity and space charge properties of polyethylene based BN nanocomposites with different doping contents were studied.The space charge was simulated numerically.Polyethylene based BN nanocomposites with different doping contents were prepared by melt blending.The microstructure of the Polyethylene based BN nanocomposites was characterized by cold field emission scanning electron microscopy.The BN nanoparticles were found to be homogeneous in the polyethylene matrix.Research on the breakdown and dielectric properties show that with the increase of doping content of BN nanoparticles,the breakdown strength of LDPE/BN nanocomposites increase first and then decrease.When the doping amount is 1%,AC breakdown strength of LDPE/BN composites reach the peak of 90.77kV/mm,which was 2.2%higher than that of pure LDPE.It can be seen that with the increasement of the doping content of BN nanoparticles,the electrical and thermal erosion resistance of the LDPE/BN composites will be improved.The dielectric constant and dielectric loss of LDPE/BN nanocomposites increase with the increasement of temperature,and they also increase with the increasement of the field intensity.The dielectric constant and dielectric loss of LDPE/BN nanocomposites will decrease first and then increase with the increasement of BN doping content.The conductivity of LDPE/BN composites with different doping content increases with the increasement of field strength.At the same field intensity,the current values of LDPE and 0.1%,0.5%,3%doped LDPE/BN composites increase with the increasement of temperature.At high temperature and field strength,the resistivity of 3%doped LDPE/BN composites is high.The results show that the 3%doping content of the LDPE/BN composites have good insulation properties at high temperature.The space charge measurement results show that the space charge problem of pure LDPE under high electric field is very serious.The inhibitory effect of BN doping on the space charge is very obvious,and the 3%doped LDPE/BN nanocomposites have the best effect on the space charge inhibition.The simulation results show that the numerical simulation of the space charge behavior is consistent with the space charge distribution.In summary,the 3%doped LDPE/BN nanocomposites have the best effect on the space charge inhibition on the basis of maintaining excellent electrical insulation properties of polyethylene.