高压直流电缆用交联聚乙烯介电性能的对比研究

Comparative Study on Dielectric Properties of Crosslinked Polyethylene Used in HVDC Cable

为研究温度对直流电缆用交联聚乙烯绝缘性能的影响,选取了2种具有代表性的直流电缆用交联聚乙烯和1种交流电缆用交联聚乙烯进行对比研究。分别对其在不同温度下的直流电导率和空间电荷集聚特性进行分析。结果表明:在温度范围为20~70℃时,3种交联聚乙烯试样的直流电导率随着温度的升高呈指数增大,但电导活化能有差异,直流电缆用交联聚乙烯的电导率随温度升高的变化程度较小;交流电缆用交联聚乙烯以积聚负电荷占主导,而2种直流电缆用交联聚乙烯空间电荷的平均电荷密度较小。此外,3种材料在常温下的直流击穿场强差异明显;红外光谱结果表明直流电缆用交联聚乙烯具有更少的羰基基团。2种直流电缆用交联聚乙烯分别采用提高纯净度和引入无机填料2种方式,使直流介电性能得到了改善。

To study the influence of temperature on the insulating properties of crosslinked polyethylene （XLPE） used in HVDC cable, two kinds of HVDC cable XLPE and a HVAC cable XLPE were chosen as research objects. Their DC conductivity and space charge accumulating characteristics under different temperatures were analyzed. The results show that the DC conductivity of the three XLPE samples increases exponentially with the increase of temperature at 20 ～ 70℃, but their activation energy is different. The increment of DC conductivity of the HVDC cable XLPE is smaller than that of HVAC cable XLPE. The HVAC cable XLPE accumulates negative space charge mainly, while the average density of space charge in HVDC cable XLPE is small. In addition, the DC breakdown strength of the three samples is obviously different, and the FTIR results show that the HVDC cable XLPE contains less carbonyl group. The DC dielectric properties of the two HVDC cable XLPE samples are improved by increasing the high purity and introducing inorganic fillers.