Space charge accumulation under effects of temperature gradient and applied voltage reversal on solid dielectric DC cable

Abstract

Abstract:A well-known fact of the existence and accumulation of space charge within the insulating material poses threat to the reliability in the operation of dc power cables. When power cables are loaded under high voltage direct current (HVDC), temperature gradient is developed across the insulation. Results of space charge evolution in commercial ac XLPE power cables under an application of 80 kV dc supply at different temperature gradients and during external voltage reversal are discussed in this paper. The space charge distributions were measured across the insulation of the cable by means of a modified pulsed electroacoustic (PEA) system with a current transformer attached. Therefore, a replica of a power cable under load conditions could be obtained, which allows us to investigate the formation, migration and accumulation of space charges in a power cable both without and with different temperature gradients consideration across the bulk of the insulating material during voltage reversal. Discussion will be made thoroughly in order to understand the space charge phenomenon of power cable under its service temperature as space charge accumulation during polarity reversal plays an important factor on the electric field distribution within the insulation material.

Electrical tree initiation in XLPE cable insulation by application of DC and impulse voltage

“…An investigation of the tree initiation and growth in XLPE insulating material under DC voltage conditions could provide much useful information [4][5][6]. Although the XLPE material used in DC cables may be significantly different from the XLPE used in AC cables, in this study only XLPE material applied for AC cables was used.…”

Space charge dynamics in oil and thick pressboard combined system under polarity reversal voltage

“…It is generally believed that the accumulated charges can distort the electric field distribution in the dielectric material, resulting in local electric field enhancement and leading to accelerate ageing and eventually breakdown. Moreover, many studies in HVDC power cable with polymeric insulating materials [8][9][10] suggested that the accumulated charges can enhance the electric field after reversing the applied voltage. Recently, researchers paid more attentions to the charge dynamics under polarity reversal voltage in single layer oil impregnated paper/pressboard [1l-l3].…”

Influence of voltage reversal on space charge behavior in oil-paper insulation

“…Up to now, there are only a few reports on space charge distribution under voltage polarity reversal, and most of them focus on cable material, such as LDPE, XLPE and so on [7]. The mirror image effect charge can be observed during voltage inversion, whereas a complete explanation is not available [6][7][8][9][10]. A critical amount of space charge accumulation can lead to electrical tree initiation and breakdown [11].…”

“…Due to activation energy, the temperature gradient can change the distribution of space charge, resulting in electric field modification. But the increase of reverse period can reduce the transient stress [6][7][8][11][12]. The similar study on oil-paper is fewer.…”