XLPE电缆交叉互联接线时的绝缘在线监测

XLPE电力电缆的交叉互联接线方式具有屏蔽层接地回路环流小、经济安全等优点,但因无法直接测得各段流经主绝缘的电流值的特征量而给绝缘在线监测带来了困难。为了研究电缆在交叉互联接线时的绝缘在线监测方法,介绍了电缆主绝缘各项参数的等值计算方法,并且对交叉互联接线的XLPE电力电缆的一个标准单元展开了分析,通过分析和计算其等值电路,说明了利用向量运算分析方法的理论依据,以及定量的分析了各处监测点的电流值。利用Matlab仿真可以检测到各处电流值和母线电压的向量值,计算出流过主绝缘电流向量值,然后计算出等值阻抗值、等值容抗值和介质损耗角正切值等绝缘参数,从而可以判断交叉互联电缆各段的绝缘状况。不同绝缘故障下电缆的仿真分析结果表明:无论是单相绝缘故障还是多项同时出现绝缘问题,向量运算分析方法均能准确判断各段的绝缘状况。采用此向量运算方法来判断各段电缆的绝缘状况可靠且可行,为绝缘在线监测提供了一种新方法。

Method and Emulation of Insulation On-line Monitoring of Cross-linked XLPE Cable

The wiring layout of the cross-linked XLPE electrical cable has the merit of less circulation circuit current of the shielding layer and is more economic and safe than the ordinary layout.But it is difficult to monitor the insulation situation of each segment of the electrical cable because the characteristic parameters of current which flows cross the main insulation of each segment of the cable is hard to be got by direct measurement.To investigate a new online monitoring method of cross-linked XLPE electrical cable,characteristic parameters of main insulation of each segment of the cable is investigated by the means of equivalent calculation,and a standard unit of cross-linked XLPE electrical cable is analyzed.The equivalent circuit is analyzed and calculated and basis of the theory for this method of vector analysis is presented.The dimension of current of each monitoring point is compared and analysis.The Matlab program is used to simulate the circuit of cable.By the simulation current of each segment,voltage vector of bus bar is detected.So the values of current vector,equivalent resistance,equivalent capacitance and dielectric loss angle tangent can be calculated.Thus the insulation situation of the cable can be judged from the results of calculation.The results of insulation simulation of each segment show:no matter the insulation of single phase or three-phase falls,the method of vector analysis can reflect insulation situation of each segment properly.This method can be used to judge the insulation situation of each segment of cable and this method is proved to be useful and reliable.So it is a novel method for the online monitoring of insulation of cables.