变压器油中水分对糠醛扩散及分布影响的分子动力学研究

Impacts of Water Within Transformer Oil on the Diffusion and Distribution Characteristics of Furfural by Molecular Dynamics

糠醛是电力变压器绝缘纸的老化产物,通过监测油中糠醛质量浓度可以直接评估绝缘纸的老化程度,但关于糠醛的生成机制及在油纸复合绝缘系统的分布规律至今没有形成统一的认识。在众多的因素中,水分被认为在影响糠醛的生成速率及其在油纸复合绝缘系统分布的过程中具有重要作用,但其作用机制却不够明晰。为此,利用分子模拟手段分别构建出糠醛分子在无水、水与油之质量比分别为1%、3%和5%的环烷基矿物绝缘油中的扩散模型并进行动力学仿真和分析。通过考察糠醛与含水油介质的相互作用、氢键成键特性以及糠醛的扩散现象,研究了水分影响糠醛在环烷基矿物绝缘油中扩散及分布规律的微观机制。研究结果表明,油中水分可以提升矿物油对于糠醛的吸附能力并增加糠醛在油中的溶解度,进而改变糠醛在油纸复合绝缘系统中的分布比例;同时油中水分抑制了糠醛的自由扩散,这将对糠醛在油中的均匀分布产生负面影响。

Furfural is an aging by-product of power transformer insulation paper.The concentration of furfural can be directly used as a tool to evaluate the aging extent of insulation paper.However,no universally acknowledged production mechanisms and distribution laws of furfural in oil-paper system have been obtained.Among various influential factors,water is considered to play an important but ambiguous role in effecting furfural＇s production rate and distribution.Therefore,four naphthenic mineral oil models,of which the water contents were set to 0%,1%,3% and 5% respectively,were constructed by means of molecular modeling.Molecular dynamics were performed on the models subsequently.By investigating interactions between furfural and ambient media,hydrogen bonding and diffusion phenomenon of furfural in oil,the microscopic mechanism of water influencing the diffusion and distribution characteristics of furfural in oil-paper composite system was revealed.Research results show water in transformer oil would significantly enhance oil＇s ability in absorbing furfural and improve solubility of furfural in oil as well.Moreover,water in transformer oil suppresses the free diffusion of furfural in oil which will exert native influence on furfural＇s homogeneous distribution in oil.