退役高压XLPE电缆绝缘空间电荷行为研究

文中对两回110 kV退役高压交联电缆进行180 a预鉴定试验,目的在于研究不同运行年限的退役高压交联电缆老化前后的空间电荷行为差异,并评估电缆重新投入实际运行的可靠性。通过电声脉冲(PEA)法测量试验前后绝缘层交联聚乙烯(XLPE)试样的空间电荷分布,结合傅里叶红外光谱(FTIR)实验、X射线衍射(XRD)实验揭示试样的微观结构、聚集态结构状态变化与空间电荷的迁移、积聚和消散过程的潜在关系。实验结果表明:实际运行16 a的电缆绝缘由于存在大量杂质使得空间电荷的积聚严重,老化试验后,杂质的减少和淬火反应使得空间电荷的积聚降低且消散过程加快;实际运行32 a的电缆绝缘空间电荷的积聚和消散过程缓和,老化试验后,由于绝缘降解作用和晶态结构的破坏使得空间电荷的积聚加剧且消散过程变得缓慢。

Space charge behavior of retired high-voltage XLPE cables

In this paper, two retired high-voltage cross-linked cables with service years of 16 and 32 were chosen to conduct a 180-day prequalification test to research the diversity of the behavior of space charge and evaluate the reliability of reusing these cables for practical operation. The behavior of space charge in XLPE insulation of the samples before and after the aging test was tested by the pulse electro acoustic (PEA) method, and the space charge characteristics of the samples was investigated. Fourier infrared spectroscopy (FTIR) and X-ray diffraction (XRD) experiments were used to observe changes on micro-structure and aggregation structure of each sample and reveal the potential rela-tionship between the structural changes and the space charge behavior, including the characteristic of migration, accumulation and dissipation of space charge. The results show that the impurities causing a severe accumulation of space charge inside the samples of the cable with service years of 16. After the accelerated aging test, the reduc-tion of impurities and the annealing effect have decreased the accumulation of the space charge and speeds up the dissipation process. On the contrary, the accumulation and dissipation of space charge inside the cable with service years of 32 is moderate. After the accelerated aging test, the oxidative degradation and the destruction of the crys-talline structure have resulted in the aggravation of the accumulation of space charge and more moderate dissipa-tion process of space charge.