Space charge dynamics in double-layered insulation cable under polarity reversal voltage

To investigate space charge behavior in double-layered cable insulation, a one-dimensional axisymmetric model for bipolar charge transport is built in this work. Effects of temperature gradient and electric field gradient in the radial direction are considered. The transient distribution of space charge and electric field under polarity reversal voltage is simulated with the developed model, and then the influence of interface position is analyzed to guide the design of double-layered insulation. The results indicate that space charge and electric field distributions are affected by temperature gradient and voltage polarity. Under polarity reversal voltage, the electric field is intensified by the residual space charge generated before polarity reversal, which causes the severe electric field distortion. In addition, the comprehensive electric field distortion factor is the least when the interface is located at the middle of the insulation layer, which is more beneficial to the stable operation of cable.