高压电缆半导电缓冲层电学性能及其对电场分布的影响

    Electrical Performance of High-Voltage Cable Semi-Conductive Buffer Layer and Its Influence on Electric Field Distribution

    • 摘要: 国内外的皱纹铝护套型高压交联聚乙烯(cross-linked polyethylene,XLPE)绝缘电缆均出现了缓冲层放电烧蚀故障,而缓冲层的电学性能是影响其运行状态的重要因素之一。文中从两种不同的缓冲层材料出发,开展了不同温度、压力,以及受潮状态下半导电聚酯无纺纤维阻水布和半导电丁基橡胶带体积电阻率的测试,建立了110 kV皱纹铝护套型XLPE绝缘电缆的二维轴对称模型,分析了缓冲层体积电阻率、接触不良点个数,以及半导电丁基橡胶带结构对缓冲层电场强度的影响规律。试验结果表明:随着温度和压力的升高,以及水分的入侵,缓冲层体积电阻率呈增大趋势,且有可能超过标准值。仿真结果表明:当缓冲层与皱纹铝护套紧密接触时,缓冲层体积电阻率的改变对缓冲层处电场分布的影响较小;当缓冲层与皱纹铝护套接触不良时,随着接触不良点个数的增加,缓冲层处电场强度增大,而当缓冲层体积电阻率超过标准值时这种增大趋势更明显。同时,丁基橡胶带结构的加入与否对缓冲层与皱纹铝护套之间的电场分布影响不大,该结构的加入并不能从根本上解决缓冲层与皱纹铝护套之间的放电烧蚀故障。

       

      Abstract: Discharge and ablation failures have been observed in buffer layers of both domestic and international corrugated aluminum-sheathed high-voltage cross-linked polyethylene (XLPE) insulated cables, and electrical properties of the buffer layer are crucial factors influencing its operational performance. From the perspective of two different buffer layer materials, tests were conducted to measure volume resistivity of semi-conductive polyester non-woven water-blocking fabric and semi-conductive butyl rubber tape under varying temperatures, pressures, and moisture conditions. A two-dimensional axisymmetric model of a 110 kV corrugated aluminum-sheathed XLPE insulated cable was established to analyze the effects of buffer layer volume resistivity, the number of poor-contact points, and the structure of semi-conductive butyl rubber tape on electric field intensity in the buffer layer. Experimental results indicated that with the increase in temperature, pressure and moisture, volume resistivity of the buffer layer tended to increase, potentially exceeding standard limits. Simulation results showed that when buffer layer was in close contact with corrugated aluminum sheath, changes in its volume resistivity had a minimal impact on electric field distribution at the buffer layer. However, when poor contact existed between buffer layer and corrugated aluminum sheath, electric field intensity at the buffer layer increased with the number of poor-contact points. This increase could become more pronounced when volume resistivity of the buffer layer exceeded standard values. Additionally, inclusion or exclusion of the butyl rubber tape structure had little effect on electric field distribution between buffer layer and corrugated aluminum sheath, and its addition did not fundamentally resolve discharge and ablation failures in this region.

       

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