Abstract
Long time DC pressure on high voltage cables will lead to the accumulation of space charge in XLPE cables, thus endangering cable insulation. In order to study the effect of the thickness of semiconducting layer on the space charge in XLPE, the space charge in 10kV and 220kV XLPE sample with different thickness of semiconducting layer was measured and compared based on PEA method. Firstly, the samples were pressurized to the specified voltage, then kept this voltage for 30 minutes, then depressurized to 0, and lastly maintained for 90 minutes. The variation of space charge distribution during the pressurized stage was analyzed with the space charge density as the characteristic parameter. The results show that the space charge near the anode and cathode is accumulated by the semi-conductive coating during the period of maintaining pressure; the thicker the semi-conductive layer is, the more obvious the accumulation of space charge is; the longer the time of maintaining pressure, the more space charge accumulates.
Highlights
XLPE cables are widely used in power systems of various voltage levels because of their excellent electrical performance, simple structure, convenient laying and high reliability of power supply
Oscillation wave is widely used in cables with 35 kV and below voltage level because of its excellent performance, but it is seldom used in cables with 110 kV and above
One of the reasons is that people worry about the accumulation of space charge caused by DC pressurization process, which endangers cable insulation
Summary
XLPE cables are widely used in power systems of various voltage levels because of their excellent electrical performance, simple structure, convenient laying and high reliability of power supply. Scholars at home and abroad have used this method to study the space charge characteristics of XLPE insulating materials. Based on PEA method, there are a wide range of studies, mainly involving: 1)the influence of field strength, frequency, temperature, cross-linking by-products and other factors on space charge accumulation of XLPE materials; 2)the relationship between space charge distribution and insulation aging. Roy S L et al studied the effect of polarizable impurities on space charge electric field distribution in cable polymers[10]. The effects of different thickness of semi-conductive layer on space charge accumulation of 10 kV and 220 kV XLPE samples were investigated
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