微水加速变压器油纸绝缘热解的微观机制研究

Research on Microcosmic Mechanism of Transformer Oil-paper Insulation Pyrolysis Accelerated by Micro-water

微水是导致变压器油纸绝缘劣化的主要因素之一,探讨其在油纸绝缘热裂解过程中的作用机理具有重要意义。本文建立了油纸绝缘的复合分子模型,基于反应分子动力学模拟了含有微水的油纸绝缘热解的过程,探究了水分子在油纸绝缘热解不同阶段的作用机理,并分析氢离子和氢自由基在热裂解中的作用。结果表明:含有微水的油纸绝缘复合模型中,水分子、氢气等小分子初始生成时间早,而且生成速率和数量均高于不含微水的油纸绝缘复合模型。通过分析反应路径发现,在初始阶段水分子先是破坏绝缘纸的氢键网络;随着高温时间延长,水分子作为催化剂促进绝缘纸裂解;随着反应进行,水分子作为载体携带羧酸氢离子向绝缘油扩散,促进绝缘油热裂解。在反应过程中,羧酸氢离子具有加速绝缘热裂解的作用,并且在与水分子的共同作用下,油纸绝缘会协同加速裂解,而氢自由基不具有加速作用。

Micro-water is one of the main factors leading to the deterioration of transformer oil-paper insulation, so it is important to discuss the affecting mechanism of micro-water in the pyrolysis process of oil-paper insulation. In this paper, a compound molecular model of oil-paper insulation was established, and on the basis of reactive molecular dynamics, the pyrolysis process of oil-paper insulation containing micro-water was simulated. The affecting mechanism of water molecules in different pyrolysis stages of oil-paper insulation was investigated, and the roles of hydrogen ions and hydrogen radicals in the pyrolysis process were analyzed. The results show that in the oil-paper insulation composite model containing micro-water, the initial formation time of small molecules such as water and hydrogen molecules is earlier, and their formation rate and quantity are higher than that of the oil-paper insulation composite model without micro-water. By analyzing the reaction path, it is found that at the initial stage, water molecules firstly destroy the hydrogen bond network of insulating paper, and with the increase of high temperature time, the water molecule act as a catalyst to promote the pyrolysis of insulating paper. As the reaction proceeds, water molecules as carriers carrying hydrogen carboxylate ions diffuse into the insulating oil,which promotes the pyrolysis of insulating oil. During the reaction process, the hydrogen carboxylate ion has the effect of accelerating the insulation pyrolysis, and which can accelerate the pyrolysis of oil-paper insulation synergistically with water molecules, while the hydrogen radical does not have the accelerating effect.