Research On MgO/LDPE Nanocomposite Electric Tree Resistance Properties

Polymer nanocomposite materials have been attracting much attention as a new material because the properties of the original material can be drastically improved by adding a few percent of nano-sized filler. MgO / LDPE which has the significantly inhibited ability of space charge has been successfully used in HVDC systems. Electrical tree is the bottleneck of insulation operational reliability. This paper focuses on the effect of the nano particles about electrical tree.First, research and experiments about MgO/ LDPE nanocomposite materials on electrical tree and space charge in recent year have been summed up. Theoretical model of nano dielectrics have been introduced. Secondly, in order to satisfy the precision of needle tip radius of curvature in electrical tree experiment, two methods have been adopted to detect needle tip radius of curvature. The first method based on cubic-spline interpolation algorithm realized automatic detection of radius of curvature designed by VC++. Second method we designed FIR filters using design in MATLAB, both method have good consistency. Electric tree initiation experiment is done, data dispersion is good.Secondly, the maximum field strength is simulated in the needle plate electrode use of ANSOFT. Simulation results and MASON formula have been compared changing the radius of curvature and the needle plate distance. Radius of curvature has strong influence on that the maximum field, the simulation results is more accurate when theradius of curvature is small.Finally, electric tree resistance of crosslinking by-products have been validated by electric tree experiments about XLPE with different heat treatment. Electric tree and space charge experiment of different filled amount selfemade MgO/LDPE have been done. MgO/LDPE composite electric tree initial voltage was higher than base stock, tree grew slower with time, tree have long delay period. Experiments show that composite with nanoparticles add material electric tree resistance ability. With the increased amount of filling, space charge in composite material significantly reduced, which explained composite material have space charge inhibition ability, the ability of space charge inhibition was stronger, electronic infect is mord difficult, the material damage around needle tip is weaken, thus composite material displayed electric tree resistance.