去极化电流弛豫谱线特性的油纸绝缘老化判别研究

Research of depolarization current relaxation spectrum characteristics in identifying oil-paper insulation aging

为深入研究油纸绝缘老化状态与介质内部弛豫响应的内在联系,首先对去极化电流(DC)内部弛豫特性进行研究,引入弛豫谱线和弛豫谱线能量这2个新特征量,其次应用二次微分法确定去极化电流弛豫谱线个数,并探讨弛豫谱线个数及弛豫谱线能量与绝缘老化状况间的关系,从而得到油纸绝缘老化的判别方法。研究结果表明,随着绝缘系统老化程度加重,去极化电流所含的弛豫谱线个数增加,且弛豫谱线能量对老化变化灵敏,它随绝缘水平的降低而显著增加。因此,弛豫谱线个数和弛豫谱线能量可作为绝缘诊断的判据,其为准确评估油纸绝缘老化状态提供一种可靠有力的分析手段,具有一定的参考价值。

To further explore the inner link between oil paper insulation aging and dielectric relaxation response, the inner relaxation characteristics of depolarization current（DC） are investigated. Two new characteristic quantities including relaxation spectrum and its energy are introduced. The second order differentiation method is applied to determine the number of depolarization current relaxation spectrums, and aging condition of oil-paper insulation＇ s relationships with both the number of relaxation spectrums and its energy are dis- cussed. A method to distinguish aging condition of oil-paper insulation is derived. Results show that, as the dielectric aging is deepening, the number of relaxation spectrums is growing, and the relaxation spectrum energy is sensitive to aging condition and increases with the lower insulation level. The number of relaxation spectrums and its energy can be accepted as the criterion of insulation diagnosis. An effective means is realized to assess the oil-paper insulation aging status ,which provides a certain reference value.