油浸式变压器匝间纸绝缘中水分扩散特性  

Moisture Diffusion Characteristics in Turn-to-turn Paper Insulation of Oil-impregnated Transformers

作　　者：高萌[1] 张乔根[1] 丁玉琴[1] 王同磊 倪鹤立 袁炜雄 GAO Meng;ZHANG Qiaogen;DING Yuqin;WANG Tonglei;NI Heli;YUAN Weixiong(School of Electrical Engineering,Xi'an Jiaotong University,Xi'an 710049,China)

机构地区：[1]西安交通大学电气工程学院,西安710049

出　　处：《高电压技术》2019年第1期117-123,共7页High Voltage Engineering

摘　　要：匝间纸绝缘是决定油浸式变压器纵绝缘水平的重要绝缘结构之一,因其常由多层绝缘纸绕制而成,故水分在其中的扩散特性与在厚纸板中的有所不同。另外,相比于其他部位的固体绝缘,匝间纸绝缘要承受更高的温度和更快的温度变化,因此其内部水分的扩散更为明显。论文首先探讨了匝间纸绝缘与厚纸板在结构方面的差异,并在已有理论的基础上对典型匝间纸绝缘中水分的扩散过程建立了数学模型;然后设计了三类相同厚度、不同层数的纸绝缘模型,通过实验研究了典型纸绝缘在厚度方向上的水分分布特征及其随时间的变化规律,并研究了温度对水分分布和扩散速度的影响;最后将实验数据转化为离散形式并代入模型求解,获得了模型中特征系数与水分、温度的函数关系,研究了绝缘纸层数对水分扩散速度的影响。实验结果表明:温度对水分在多层绝缘纸中扩散速度的影响较为显著,同等厚度纸绝缘的层数越多,水分扩散就越慢。进一步分析发现,不同层数的纸绝缘模型所对应的特征系数之间存在差异,结合典型纸绝缘的结构特征分析表明,相邻纸层间微油隙的存在是造成这一差异的主要原因。In oil-impregnated transformers, paper insulation between turns determines the series insulation strength of the facility. For the multilayer structure of the paper insulation, the diffusion process of moisture in it differs from that in thick pressboard. Besides, compared to the solid insulation elsewhere in the facility, paper insulation between turns endures higher temperature with faster rising speed, which leads to an obvious moisture diffusion. We comparatively investigated the difference in structure between multilayer paper and thick-pressboard. Based on the existing theory, a discrete mathematical model was set up to simulate the migration process of moisture in turn-to-turn paper insulation. Thereafter, we designed three types of paper insulation models with the same thickness and different layers. In the experiment, we investigated the characteristic of moisture distribution in paper layers in the thickness direction and its variation with time and the influence of temperature on moisture distribution and its diffusion speed were experimentally studied. The experiment results were discretized and put in the mathematical model, and the relevant characteristic coefficients related to the moisture content and temperature were obtained. Relations between the layer of insulation paper and the moisture migration process were also experimentally studied. Results show that temperature significantly influences the moisture diffusion speed in multilayer paper insulation. Besides, the speed of moisture diffusion speed decreases with increasing layers of the paper insulation with the same thickness. Further analysis show that the characteristic coefficients related to moisture diffusion differ among different models. Finally, taking the structure features of typical paper insulation into consideration, we have found that micro oil gap existing between paper layers leads to the difference of moisture diffusion speed in different models.

关 键 词：油浸式变压器 匝间纸绝缘 微油隙 水分扩散 特征系数 温度 

分 类 号：TM855[电气工程—高电压与绝缘技术]