Effect of space charge accumulation on electric field distribution of high voltage cable

Abstract

Space charge location and amount are key factors affecting the local insulation performance. This work focuses on the effect of space charge distribution and charges accumulation amount on the electric field distribution of HVDC cables. In the experiment, the dielectric properties and the conductivity properties of the specimen from the operating cable are measured. The simulation model of the electric field of HVDC cables is established, and the effect of charge accumulation on the electric field in the insulation layer are calculated. The experimental results indicate that the dielectric constant of the XLPE cable insulation layer gradually decreases with temperature, from 2.43 at room temperature to 2.21 at 90°C. Conductivity increases with temperature from 5.23×10-15S/m at room temperature to 1.58×10-12S/m at 90°C. The experimental parameters are brought into the simulation model and the calculation results show that the maximum electric field of the insulation layer increases from 24.5 kV/mm to 26.2 kV/mm when the positive charges accumulate between the insulation layer and the inner semi-conductive layer, and it decreases to 22.8 kV/mm when the negative charge accumulate.