In the LCC-HVDC transmission system

the the insulation of XLPE cable not only withstands the temperature gradient of the inner high and the outer low for a long time under actual conditions

but also faces the reversal adjustment of the power flow and withstands the polarity reversal electric field

which seriously affects the XLPE insulation performance. Therefore

the effects of temperature gradient and polarity reversal voltage conditions on the dynamic characteristics of space charge and electric field distortion in XLPE are studied based on the bipolar charge transport model. The result shows that with the increase of the temperature gradient

the charge of the same polarity increases near the high temperature side

and this part of the residual charge appears as the charge of the opposite polarity after voltage inversion

which enhances the electric field here. Under normal temperature

the faster the reversion of voltage polarity is

the more the residual charge is

and the higher the maximum electric filed after the reversion is. However

under the temperature gradient

the faster the polarity reversion is

the more the neutralized residual charge before the reversion is and the lower the maximum electric field after the reversion is. The higher the applied voltage is after the reversion

the more the residual charge near the high temperature side is and the higher the maximum electric field after the reversion is.