Dynamics of an impurity ion transport in oil‐paper insulation under various electric fields

Ren, Yuanyang; Wang, Yang; Zhang, Qiankai; Xiong, Jiayu; Cao, Wen; Lv, Zepeng; Wu, Kai

doi:10.1049/hve2.12361

Cited by 3 publications

(1 citation statement)

References 64 publications

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“…As another alternative, it is possible to adjust the potential structure of the EDL on the liquid side by introducing chemically active atoms, such as Na or F atoms at the interface, and then an EDL structure (Helmholtz layer) is directly introduced into the molecular model [14,15]. By increasing or decreasing the number of positive or negative ions in the electrolyte, an EDL can also be formed at the interface without the addition of additional atoms [18,25]. Additionally, polaronic charge transfer states can be generated using the occupation matrix control method, and then the amount of charge transfer at the interface can be modified accordingly [26].…”

Section: Introductionmentioning

confidence: 99%

A first-principles study of the formation and regulation of the electric double layers at Cu (0 0 1)/mineral oil interfaces

Ren,

Zhang,

Wang

et al. 2024

J. Phys. D: Appl. Phys.

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Copper-mineral oil interfaces are key components of oil-impregnated power transformers and are commonly believed to be one of their weak points. The formation of an electric double layer (EDL) at this interface as a result of charge accumulation and transfer is crucial to its insulating properties, but a molecular-level understanding of this phenomenon remains unclear. To understand this fundamental aspect, we have investigated the effect of different EDLs on the electric potential and interfacial potential barrier between copper and mineral oil by using first principle calculations. Based on the calculations, the EDL is shown to reduce the interfacial potential barrier and enhance the diffusion of oil molecules at the interface when the copper side is negatively charged and the mineral oil side is positively charged. In contrast, when the copper side is positively charged and the mineral oil side is negatively charged, the corresponding EDL can increase the interfacial potential barrier and reduce the diffusion of oil molecules at this interface. Our findings shed light on the relationship between the structure of EDLs and their electrical properties in oil-impregnated power transformers.

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Section: Introductionmentioning

confidence: 99%

A first-principles study of the formation and regulation of the electric double layers at Cu (0 0 1)/mineral oil interfaces

Ren,

Zhang,

Wang

et al. 2024

J. Phys. D: Appl. Phys.

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Microstructure‐ionisation potential relationship analysis for understanding the molecular ionisation difference of natural esters during the impulse discharge via DFT calculation

Zhang,

Hao,

et al. 2024

High Voltage

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Understanding the impulse discharge behaviour of natural ester (NE) is crucial for its safe application in high‐voltage transformers. The ionisation potential (IP) of triglycerides plays a significant role in the process of molecular ionisation during impulse discharge for NE. The correlation coefficients between molecular size, frontier orbital, electrostatic potential, polarity, and IP were analysed. And the quantitative microstructure‐IP model for triglycerides were built, which revealed that IP is strongly related to the highest occupied molecular orbital (HOMO) energy EHM, as well as the average value of positive electrostatic potential Vp(+), the average value of negative electrostatic potential Vp(−), and the surface area of negative electrostatic potential S(−). The HOMO and negative electrostatic potentials of saturated triglycerides are predominantly linked to the carbonyl O atoms. Conversely, in unsaturated triglycerides, the influence of C=C double bonds on HOMO and negative electrostatic potentials is more pronounced. Therefore, the IP of unsaturated NE with C=C bonds is lower than that of saturated NE, rendering it more susceptible to ionisation under a strong electric field which is unfavourable for impulse breakdown voltage. The structure‐property correlation analysis is valuable for understanding ionisation mechanism during the impulse discharge breakdown of NE at the microscopic level.

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Molecular Simulation of the Water Diffusion Behavior and Electronic Properties of Boron-Nitride-Composited Mineral Oil

Wang,

Yan,

Cui

et al. 2024

Molecules

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Despite the fact that doping nanoparticles into insulating transformer oil has proven to be an effective method of enhancing its dielectric and electrical properties, it remains unclear how different types and surface conditions of nanoparticles may affect their dielectric and electrical properties. Therefore, the effect of doping various types of BN nanoparticles (nanosphere, nanotube, and nanosheet) in insulating mineral oil (MO) on the diffusion properties of water molecules and electrical properties across the BN/MO interface was investigated using molecular dynamics (MD) and Density Functional Theory (DFT) simulations. Our results show that different surface morphology and grafted functional groups in different types of BN nanoparticles have a significant impact both on the water diffusion behavior and the interfacial potential barrier across the interface between BN and MO. In the MO system directly doped by BN nanospheres, water diffusion behavior is not significantly restricted. However, grafting -NH2 polar groups onto the BN nanoparticle surface may significantly limit the diffusion behavior of water due to the strong attraction between the -NH2 polar groups and water molecules; the most significant effect is with nanospheres, followed by nanotubes and nanosheets. In terms of electrical properties across the interface between BN and MO, the h-BN surface (derived from BN nanosheets and nanotubes) acts as a trap for electrons in MO (−0.59 eV), while the c-BN surface (derived from BN nanospheres) acts as a potential barrier for electrons in MO (1.45 eV), and it is noteworthy that the presence of water molecules near the interface between BN and MO has little impact on the potential barriers. Advancing a fundamental understanding of the electrical and water diffusion properties of MO in correlation with the surface morphology of different types of nanoparticles is key to improving the insulation properties of oil-impregnated power transformers.

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Dynamics of an impurity ion transport in oil‐paper insulation under various electric fields

Cited by 3 publications

References 64 publications

A first-principles study of the formation and regulation of the electric double layers at Cu (0 0 1)/mineral oil interfaces

A first-principles study of the formation and regulation of the electric double layers at Cu (0 0 1)/mineral oil interfaces

Microstructure‐ionisation potential relationship analysis for understanding the molecular ionisation difference of natural esters during the impulse discharge via DFT calculation

Molecular Simulation of the Water Diffusion Behavior and Electronic Properties of Boron-Nitride-Composited Mineral Oil

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