Effect of Continuous Polarity Reversals at Different Temperatures on the Space Charge Characteristics of XLPE

In DC transmission systems, both high temperature and polarity reversal voltage can influence the transport of space charges, leading to insulation failure in severe cases. Consequently, this study primarily investigates the space charge distribution and transient electric field distortion of XLPE when subjected to four consecutive polarity reversals at temperatures ranging from
$30^{\circ}\mathrm{C}$
to
$90^{\circ}\mathrm{C}$
. The effects of temperature and polarity reversal on the transport of space charges are examined. The results indicate that temperature influences the migration rate of charge carriers and the injection/extraction rate at electrodes. With increasing temperature, the depth of charge distribution expands from 60
$\boldsymbol{\mu}\mathbf{m}$
to 200
$\boldsymbol{\mu}\mathbf{m}$
. Due to the influence of electrode materials on charge injection, the concentration of injected electron holes is higher during positive polarity voltage. A sharp increase in electric field distortion rate occurs during the transition from negative to positive voltage. At
$30^{\circ}\mathbf{C}$
, an observable increase in Heteropolar charges within the specimen is evident with an increase in the number of polarity reversals, while at
$90^{\circ}\mathbf{C}$
, an increase in both depth and density of charge accumulation within the specimen is observed with an increase in the number of polarity reversals.