基于传递函数分析的变压器油纸绝缘老化时域介电特征量研究

发布时间：2018-03-10 11:52

本文选题：油纸绝缘　切入点：极化去极化电流　出处：《西南交通大学》2017年硕士论文　论文类型：学位论文

【摘要】：变压器的油纸绝缘系统在电磁场、高温、机械应力和水分等多种因素的协同作用下逐渐老化,导致变压器的电气和机械绝缘性能随同劣化,所以油纸绝缘系统性能的优劣决定了变压器的使用寿命。水分作为油纸绝缘老化的产物和催化剂,是加速油纸绝缘系统老化的一个关键因素,因此准确地评估油纸绝缘系统的水分含量具有十分重要的学术意义。现有研究主要是定性分析时域介电谱与油纸绝缘老化状态之间的相关关系,如何采取有效的方式提取出特征量,定量评估油纸绝缘老化程度和水分含量,特别是不受变压器的几何尺寸影响的特征量一直是该领域的研究难点,因此针对这些问题进行进一步研究具有重要的实际意义。本文在实验室条件下对不同老化程度和水分含量的油浸绝缘纸试样进行PDC测试,分析了上述条件对极化去极化电流曲线的影响,基于扩展Debye模型和传递函数分析法分别提取了评估老化程度和水分含量的时域介电特征量。研究结果表明:低水分含量条件下,大时间常数极点对油浸绝缘纸聚合度十分敏感,能够定量评估绝缘纸的老化程度;对系统极点进行有效信息融合,提取出的优化特征量避免了极点的选取方式给评估准确性带来的影响,在定量评估绝缘纸板老化程度时具有更高准确性,并且,此特征量与绝缘纸板的尺寸大小和几何结构无关;传递函数零点对绝缘纸水分含量十分敏感,其中临界零点包含的绝缘纸水分含量信息最为全面且干扰信息最少,表征绝缘纸水分含量效果最好,对各零点进行有效信息融合提取出的优化特征量在评估绝缘纸水分含量时具有更高的准确性,并且,此特征参量也与绝缘纸板的几何尺寸无关。通过不均匀加速热老化实验,分析了实际不均匀老化条件对表征老化程度和水分含量的时域介电特征量评估效果的影响。试验结果表明:不均匀热老化试样的修正Debye模型和扩展Debye模型参数间差别非常小,可以用扩展Debye模型对不均匀老化的绝缘纸进行描述;任一层绝缘纸的聚合度皆不能作为衡量不均匀老化绝缘纸老化程度的指标,但是中间层绝缘纸聚合度与所提特征量相关关系最好,可以期待有一个能够衡量不均匀老化绝缘系统老化程度的综合聚合度与所提的极点特征量之间存在定量关系·,在绝缘纸不均匀老化一定时间后,提取的时域介电特征量与绝缘纸水分含量之间依然存在较好的函数关系,其评估准确性受到不均匀老化的影响非常小,即不均匀热老化情况下,提出的时域介电特征量依然对绝缘纸水分含量十分敏感,因此,此特征量更加适合用于现场服役变压器的绝缘系统老化状态评估。
[Abstract]:The oil-paper insulation system of the transformer is aging gradually under the synergistic action of electromagnetic field, high temperature, mechanical stress and moisture, which leads to the deterioration of the electrical and mechanical insulation performance of the transformer. Therefore, the performance of oil-paper insulation system determines the service life of transformer. Water, as the product and catalyst of oil-paper insulation aging, is a key factor to accelerate the aging of oil-paper insulation system. Therefore, it is of great academic significance to accurately evaluate the moisture content of oil-paper insulation system. The existing studies mainly focus on the qualitative analysis of the correlation between the time-domain dielectric spectrum and the aging state of oil-paper insulation. How to extract the characteristic quantity in an effective way and evaluate quantitatively the aging degree and moisture content of oil-paper insulation, especially the characteristic quantity which is not affected by the geometric size of transformer, has been the research difficulty in this field. Therefore, it is of great practical significance to further study these problems. In this paper, the samples of oil-immersed insulator paper with different aging degree and moisture content are tested by PDC under laboratory conditions. The influence of the above conditions on the polarization depolarization current curve was analyzed. Based on the extended Debye model and the transfer function analysis method, the time domain dielectric characteristics were extracted to evaluate the aging degree and the moisture content, respectively. Large time constant poles are very sensitive to the degree of polymerization of oil-immersed insulator paper and can be used to quantitatively evaluate the aging degree of insulator paper. The extracted optimization features avoid the influence of the selection of poles on the accuracy of the evaluation, and have higher accuracy in quantitative evaluation of the aging degree of insulating paperboard. This characteristic quantity has nothing to do with the size and geometric structure of insulating paperboard, and the transfer function 00:00 is very sensitive to the moisture content of insulator paper, among which critical 00:00 contains the most comprehensive information and the least interference information. The water content of insulator paper is the best, and the optimized characteristic quantity extracted by effective information fusion at 00:00 has higher accuracy in evaluating the moisture content of insulator paper. This characteristic parameter is also independent of the geometric size of insulating paperboard. The effect of the actual non-uniform aging conditions on the evaluation effect of the time-domain dielectric characteristic of the aging degree and moisture content is analyzed. The experimental results show that there is very little difference between the parameters of the modified Debye model and the extended Debye model of the non-uniform thermal aging sample, and the difference between the parameters of the modified Debye model and the extended Debye model is very small. The extended Debye model can be used to describe the nonuniform aging insulator paper, and the degree of polymerization of any layer of insulator paper can not be used as an index to measure the aging degree of inhomogeneous aging insulator paper. However, the degree of polymerization of the intermediate layer insulator paper has the best correlation with the proposed characteristic quantity. It can be expected that there is a quantitative relationship between the degree of synthesis polymerization that can measure the aging degree of the inhomogeneous aging insulation system and the pole characteristic quantity proposed. After a certain period of inhomogeneous aging of the insulator paper, There is still a good functional relationship between the time domain dielectric characteristic and the moisture content of the insulator paper, and the accuracy of the estimation is very little affected by the inhomogeneous aging, that is, under the condition of non-uniform thermal aging. The time domain dielectric characteristic is still very sensitive to the moisture content of insulator paper, so it is more suitable for evaluating the aging state of insulation system of transformer in service in the field.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM855

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