Tian Wenxin, Tang Chao, Wang Qian, Zhang Shiling, Yang Yali
College of Engineering and Technology, Southwest University, Chongqing 400715, China.
Electric Power Research Institute of State Grid Chongqing Electric Power Company, Chongqing 401123, China.
Materials (Basel). 2018 Nov 26;11(12):2373. doi: 10.3390/ma11122373.
Moisture has a significant effect on the internal insulation performance of transformers, and is closely related to the breakdown voltage of transformer insulating oil. In the present work, we studied the effect of nano-SiO₂ particles on the diffusion of water in insulating naphthenic mineral oil using molecular dynamics simulation. Six models were established, three of which contained nano-SiO₂ particles together with water concentration of 1 wt.%, 2 wt.%, or 3 wt.%. For each model variations in free volume, mean square displacement, and interaction energy were assessed. The addition of nano SiO₂ particles was found to reduce the free volume fraction of the model and as well as the free motion of water molecules in the oil. These particles also increased the interaction between the oil and water molecules, indicating that insulating oil containing nano-particles has a greater binding effect on water. The diffusion coefficient of water in oil containing nano-SiO₂ particles was reduced, such that water molecules were less likely to diffuse. The results also show that these particles adsorb water molecules in the oil and to reduce diffusion. Consequently, the addition nano-scale SiO₂ particles could potentially improve the breakdown voltage of the insulating oil.
水分对变压器的内部绝缘性能有显著影响，并且与变压器绝缘油的击穿电压密切相关。在本研究中，我们使用分子动力学模拟研究了纳米二氧化硅颗粒对水在环烷基矿物绝缘油中扩散的影响。建立了六个模型，其中三个模型含有纳米二氧化硅颗粒，水的浓度分别为1 wt.%、2 wt.%或3 wt.%。对每个模型评估了自由体积、均方位移和相互作用能的变化。结果发现，添加纳米二氧化硅颗粒会降低模型的自由体积分数以及油中水分子的自由运动。这些颗粒还增加了油与水分子之间的相互作用，表明含纳米颗粒的绝缘油对水具有更大的束缚作用。水在含纳米二氧化硅颗粒的油中的扩散系数降低，使得水分子扩散的可能性减小。结果还表明，这些颗粒吸附油中的水分子并减少扩散。因此，添加纳米级二氧化硅颗粒可能会提高绝缘油的击穿电压。
