The Evolution of Space Charge and Electric Field in HVDC Cable under Polarity Reversal Voltage Superimposed with Temperature Gradient

The evolution of space charge and electric field under polarity reversal voltage superimposed with temperature gradient (ΔT) in the insulation of HVDC cable are studied. The results show that the maximum electric field (E
max
) appears near the inner shielding layer during polarity reversal. As the ΔT rises, the E
max
during polarity reversal aggravates gradually. Extending the voltage reversal period enhances the accumulation of negative charges during the process, thereby mitigating the E
max
after the polarity reversal. During voltage polarity reversal, the variation trend of net charges on the inner side aligns with that of electrons. Hence, the electron transport behaviors near the inner shielding layer constitute an important factor influencing electric field distortion.