Static dielectric constant and dielectric loss of cellulose insulation: Molecular dynamics simulations

High voltage

article

Wei Hou¹  Lijun Yang¹  Yang Mo¹  Fei Yin¹  Youyu Huang²  Xiaoling Zheng² 

[1] State Key Laboratory of Power Transmission Equipment and System Security and New Technology, Chongqing University;Hunan Guangxin Technology Co, Ltd

关键词: dielectric liquids;    dielectric losses;    dielectric materials;    dielectric properties;    electric fields;    molecular dynamics method;    permittivity;    power transformer insulation;    transformer oil;   

DOI  :  10.1049/hve2.12087

学科分类：物理（综合）

来源: Wiley

【 摘 要 】

Reducing the dielectric constant and loss of cellulose insulation can make the electric field distribution uniform in oil-paper insulation systems and decrease the heat generation in dielectric materials, thus ensuring a reliable transformer operation. To guide the experimental design from the molecular level, the fluctuation method was introduced into the molecular dynamics simulation to evaluate the static permittivity of cellulose insulation, ε s . The correlation between the dynamics parameter mean square displacement (MSD) and dielectric loss induced by orientational polarization, was investigated. The simulation results and experimental values of five types of cellulose insulation were compared to verify the rationality of the proposed method. The results indicated that the simulation values of ε s for five models were agreed well with the experimental values in terms of both the magnitude and the variation trend. The simulation time and permittivity of the surrounding medium ε RF are two key parameters, which determine the accuracy of the simulation results of ε s . Considering the convergence, 15 ns was chosen as the lower limit of simulation time. The reaction field approximation was adopted to calculate the dipole-dipole interaction instead of true interaction, that is, ε RF →∞. The MSD results reproduced the experimental trend in dielectric loss, indicating that the method can qualitatively predict the dielectric loss of cellulose insulation. Hence, these methods are sufficient to guide design experiments and provide a route to understand the mechanism of the change in dielectric properties at the molecular level.

【 授权许可】

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