电缆中空间电荷的测量与特性研究

摘要

Due to its excellent electrical performance,the cross-linked polyethylene power cables (XLPE) are widely used in power transmission and distribution lines.However,the space charge in the XLPE can distort the local strength of the electric field,and lead to the aging and breakdown of the insulation,thus the study of the distribution characteristics of the space charge in the cable insulation is of great significance.Recently,the pulsed electro-acoustic method(PEA) is widely used due to its losslessness and convenience.This paper briefly introduces the principle of the PEA method.With consideration of the temperature difference between the cable core and the outer semi-conductor,an current transformer and a temperature sensor are used to control the temperature at the cable core,and a new space charge measurement device that can be used for cable samples based on this method is developed,modifying the lower electrodes to make them suitable for the cable insulation of different thicknesses and radium.Measurements are made under different temperatures and the results show that the temperature has significant influence on the speed in the dielectric and the injection of the space charge.%交联聚乙烯电力电缆因其优异的电气性能,现已广泛应用于电力系统输配电线路中,然而由于绝缘本体中空间电荷的存在,会畸变局部场强,进而导致绝缘老化和击穿,因此研究电缆本体绝缘中空间电荷的分布具有重大意义.目前针对固体绝缘电介质,电声脉冲法测量空间电荷由于无损和方便等优势,在国内外被广泛采用.鉴于此,介绍了电声脉冲法的测量原理,并且结合实际运行情况中电缆线芯和外半导体之间存在温度差,通过穿心升流变压器和接触式温度传感器控制线芯温度,改进测量下电极形状以适应不同厚度和半径的电缆本体绝缘,设计了一套能够用于电缆本体的空间电荷测量装置,并进行了不同温度下的实际测量,实验结果表明,温度对声信号在介质中的传播速度以及空间电荷的注入影响明显.