Effect of Insulation Thickness on Space Charge Behavior and Electric Field Evolution in HVDC Cable Under Polarity Reversal Voltage

The distribution of the electric field and temperature field during polarity reversal is one of the key factors to be considered in the design of insulation layer thickness of HVDC cables. This study investigates the effect of the insulation layer thickness on the electric-thermal field distribution and space charge behavior during polarity reversal voltage. Taking ±500 kV HVDC cable as the research object, the heat conduction model and charge transport model considering impurity dissociation are established. The results show that as the insulation thickness decreases from 30 mm to 22 mm, the insulation temperature gradient (
$\Delta \mathrm{T}$
) decreases while the average electric field and space charge density increase. With the effect of increasing space charge density, although the maximum value of the electric field (
$E_{\max}$
) increases during DC voltage and polarity reversal voltage, the electric field distortion rate (
$C_{\mathrm{E}}$
) decreases obviously.