Study on the influencing factors of space charge dynamic behavior in XLPE insulation under alternating current electric field

Abstract

The dynamic behavior of space charges is one of the potential factors that cause electrical aging. In this paper, a bipolar space charge transport model was established under an AC electric field in cross-linked polyethylene. The effects of physical parameters on the dynamic behavior of space charges in an AC electric field were explored by changing the injection barrier heights, mobilities, trapping coefficients, and detrapping barrier heights of positive and negative charges. The effects of voltage conditions on space charge behavior were explored by changing the amplitude and frequency. The effects of temperature were studied by setting a temperature gradient similar to that of real cable operation. The asymmetry of the physical parameters could seriously aggravate the accumulation of space charges in the AC field. A set of physical parameters based on these results was identified. Both the increase in voltage amplitude and decrease in frequency enhanced the amount of and penetration into the insulation of the accumulated space charge. The dynamic behaviors of the space charges were more active with increased voltage amplitude and frequency. The temperature gradient in the cable insulation implies that the degree of accumulation, penetration into material, and activity of dynamic behaviors of the space charges at the warmest electrode are greater than those at the coldest. Compared with the DC field, the dynamic behavior of space charges in the AC electric field is more active and releases more energy. This research provides a theoretical basis for inhibiting the accumulation of space charges in an AC electric field.

Enhanced electrical insulation properties of 2-isopropenyl-2-oxazoline grafted polypropylene for high voltage direct current power cables

“…Space charge accumulation is a common crucial issue of polymers, which could result in electrical degradation, partial discharge, local electric field distortion and shortened service life [10][11][12][13]. Doping, nanocomposite, and grafting modification approaches have been widely adopted to capture the accumulated space charges by inducing deep traps [14][15][16][17][18][19][20][21][22][23][24][25][26].…”

Behaviour and mechanisms of molecular vibrations induced by a pulsed voltage in a silicone elastomer used for device encapsulation

“…Insulation degradation under pulsed electric fields is affected by the strength of the electric field and the application mode, which may be closely related to the unique response mechanism of the space charge in the medium [14][15][16][17][18]. Space charges accumulate at defects in insulator materials and their unique behaviour is triggered by pulsed electric fields.…”