矿用高压电缆绝缘中气隙缺陷处电场分布及影响因素分析

Analysis of electric field distribution at air gap defect and its influencing factors in mine-used high-voltage cable insulation

为了全面掌握电缆绝缘中气隙缺陷处电场分布的影响因素及规律,以矿用高压XLPE电缆为研究对象,利用ANSYS有限元软件建立了包含气隙缺陷的电缆结构模型;在对绝缘中气隙的形状、尺寸与电场强度的关系进行理论分析的基础上,仿真研究了气隙的形状、尺寸、位置及绝缘层厚度对气隙中电场分布规律的影响。结果表明,4种不同形状的气隙中,椭圆柱体气隙缺陷处的电场强度最大,且垂直于绝缘中电场方向的气隙长度越大,气隙中电场强度越大;对于气隙尺寸,r值越大,气隙处电场强度越大,而气隙大小的变化对气隙处电场强度的影响并不大;对于不同半径的气隙,随着气隙距离导体屏蔽层距离的增大,气隙处最大电场强度均先增大后减小;对于给定尺寸的气隙,随着绝缘层厚度的减小,气隙中电场强度与绝缘中电场强度均相应增大。这些结论为气隙缺陷局部放电等相关研究奠定了基础,同时也为电缆的运行与维护检修提供了技术指导。

In order to know influence factors and laws of electric field distribution with air gap defects in cable insulation,taking mine-used high-voltage XLPE cable as research object,ANSYS finite element software was used to establish cable structure model contained air gap defect.Influence of shape,size and location of the air gap and thickness of the insulating layer on electric field distribution in the air gap was simulated and studied based on theoretical analysis of relationship between shape,size and electric fieldstrength of air gap in insulation.Results show that electric field intensity of elliptic cylinder air gap defect is the largest of four different shapes of air gap,and the larger the air gap length in direction of insulation perpendicular to the field strength,the greater the field strength in the air gap.For size of the air gap,the larger the r value,the greater the field strength at the air gap,and change of the air gap size has little influence on the field strength at the air gap.For different radius size of the air gap,the maximum electric field strength at the air gap increases first and then decreases with increasing of distance between the air gap and the conductor shield.For a given size of the air gap,the field strength in the air gap and the insulation increase accordingly with decreasing of thickness of the insulation.These conclusions lay foundation for partial discharge of air gap defects,and also provide technical guidance for cable operation and maintenance.