Description of space charge transport in oil‐paper insulation using adaptive time‐stepping transient upstream finite element method

Liu, Jiefeng; Shi, Mingchen; Zhang, Yiyi; Gao, Bing; Zhang, Wei; Liang, Shuo

doi:10.1049/hve2.12084

Cited by 7 publications

(8 citation statements)

References 33 publications

(56 reference statements)

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“…Accordingly, numerous studies have further modified the BCT model to describe the experimental phenomena. [81,87,88,234,235] A schematic diagram for the typical BCT model is shown in Figure 11.…”

Section: Space Charge Simulation: From Macroscale To Microscalementioning

confidence: 99%

Space Charge Behavior in Epoxy‐Based Dielectrics: Progress and Perspective

Liu

Xie

et al. 2022

Adv Elect Materials

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temperature and complex electric field conditions. [1][2][3] Epoxy resin (EP) is a class of polymer oligomers containing two or more epoxide groups based on organic compounds (e.g., aliphatic, alicyclic, and aromatic). As a prepolymer, EP shows excellent performance after its reaction with a curing agent to form an insoluble polymer with a 3D network structure. EP has desirable insulating characteristics, [4][5][6][7] heat resistance, [8] high mechanical strength, [9] low shrinkage, [10] chemical stability, and adhesive properties, which originate from its compact structure and tunable functional groups. The above mentioned outstanding performances, along with characteristics of easy processing and formula design flexibility, enable the extensive use of EP-based materials in power equipment and electronic devices [11] (Figure 1), including bar insulation and impregnating varnish in transformers, main insulation in dry-type bushings and wall bushings, insulator in gas-insulated switchgear (GIS) and gas-insulated transmission line (GIL), epoxy molding compound for integrated circuit (IC) packaging. It is noteworthy that EPs typically possess lower glass transition temperature (T g ) compared to other high-T g dielectric polymer substitutes used in microelectronic systems such as benzocyclobutene, [12] polyimide (PI), [13] and maleimide. [14] Besides high T g , high thermal conductivity and low coefficient of thermal expansion of EPs are always desired for their industrial applications, especially from an electronic packaging perspective. To date, considerable efforts have been made to improve the heat endurance and heat dissipation capabilities of EP-based dielectric materials by inorganic particle doping [15][16][17][18][19][20][21][22][23][24] and chemical modification. [25][26][27] Furthermore, EP is also an indispensable adhesive that is extensively used in power equipment. [28][29][30][31][32] Yet, potential reliability hazards may exist during the operation of power equipment and electronic devices, especially at high temperatures and under high voltage direct current (HVDC) application, one of which is the space charge accumulation in EP-based dielectric materials. [29,30,33,34] The accumulated space charge may cause deterioration/aging and even partial discharge or dielectric breakdown of dielectric materials. [35][36][37][38][39][40] Specifically, the extensive application of EP-based dielectric materials in HVDC transmission projects eagerly calls for relevant studies on the space charge behavior Epoxy-based dielectrics are extensively used in grid-connected energy systems and modern microelectronics as electrical insulation, adhesive, and packaging components. However, space charge accumulation in epoxy-based dielectrics is a foremost factor threatening device stability and lifespan, especially under conditions of high voltage direct current and high temperatures during long-term operation, and thus are investigated systematically. This article reviews the state-of-the-art progress in understanding and r...

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Section: Space Charge Simulation: From Macroscale To Microscalementioning

confidence: 99%

Space Charge Behavior in Epoxy‐Based Dielectrics: Progress and Perspective

Liu

Xie

et al. 2022

Adv Elect Materials

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“…We performed molecular dynamics simulations at 1 atm and 300 K for 1 ns in an isothermal-isobaric (NPT) ensemble for the initial molecular structures of the five oil-paper insulation models containing Na + , OH − or CH 3 O − for structural optimisation purposes. The resulting density of mineral oil, vegetable oil with short chains, vegetable oil with long chains, insulating paper, and oil-paper blends containing Na + was 0.82, 0.85, 0.90, 1.33 and 0.88 g/cm 3 , respectively, which is close to the previous simulations using the PCFF and COMPASS force fields [25,28]. Polar groups in vegetable oil strengthen molecular interactions, resulting in a slightly higher density of vegetable oil than mineral oil.…”

Section: Molecular Modelling and Simulation Detailsmentioning

confidence: 99%

“…Interestingly, when the short-chain component C 20 H 38 O 2 of the vegetable oil model is replaced by the long-chain component C 57 H 104 O 6 , its density increases only from 0.85 to 0.90 g/cm 3 , but the ionic mobility decreases significantly. For instance, in vegetable oil with long chains, there is a 60% reduction in the ionic mobility of Na + at E = 0.03 V/Å as compared to in vegetable oil with short chains, from 1.07 � 10 −9 m 2 /V⋅s to 4.22 � 10 −10 m 2 /V⋅s.…”

Section: Modelsmentioning

confidence: 99%

“…A similar phenomenon could also be observed for the ionic mobility of CH 3 O − , where it is reduced by 90% from 4.19 � 10 −9 m 2 /V⋅s in vegetable oil with short chains to 4.07 � 10 −10 m 2 /V⋅s in vegetable oil with long chains. To determine whether the growth of density is responsible for the sharp decline in ionic mobility, we increased the pressure in the NPT ensemble in MD simulation to compress the vegetable oil with short chains until the density was increased from 0.85 g/cm 3 to 0.90 g/cm 3 , the same density as for vegetable oil with long chains. Accordingly, it has been observed that the ionic mobility of Na + in vegetable oil with short chains declined from 1.07 � 10 −9 m 2 /V⋅s to 7.11 � 10 −10 m 2 /V⋅s at E = 0.03 V/Å with the increase of model density from 0.85 g/cm 3 to 0.90 g/cm 3 .…”

Section: Modelsmentioning

confidence: 99%

“…Oil-impregnated transformers play an essential role in power conversion and transmission, and their insulation performance significantly impacts the safe operation of power systems [1]. However, the oil-paper insulation may succumb to chemical and electrical ageing or degradation after long-term operation at high voltage, which may ultimately result in its insulation failure [2,3]. A major contribution to its ageing and breakdown is thought to be made by charge accumulation and transport.…”

Section: Introductionmentioning

confidence: 99%

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

Ren,

Wang,

Zhang

et al. 2023

High Voltage

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The ionic transport process is an important counterpart to charge transport in oil‐paper insulation, and it significantly impacts oil flow electrification at the oil‐paper interface. Despite this, the dynamics of this phenomenon and the underlying mechanisms remain unclear, particularly at the molecular level. To understand this fundamental aspect, we conduct Molecular Dynamics study on the transport behaviour of an impurity ion in different oil‐paper insulation models under various external electric fields. Different influence factors, such as external electric fields, temperatures, and local structural characteristics, are investigated in relation to the corresponding ionic mobility in different polymer models. According to the simulations, ionic mobility and its response to electric fields are higher in weaker electrostatic models. As a result, mineral oil exhibits the highest ionic mobility and the most substantial enhancement of ionic mobility by external electric fields, followed by vegetable oil, oil‐paper blends, and insulating paper. This significant deviation in ionic mobility between oil and paper leads to the formation of an electric double layer near the oil‐paper interface. The underlying physical mechanisms of different ionic mobility and its response to the electric field in different polymer models could be explained by the different polymer structural influences in terms of interaction energy and coordination numbers in a static manner, as well as by the interactions between the impurity ion and its surrounding atoms in terms of lifetime correlation functions and velocity autocorrelation functions in a dynamic manner. In addition, the influence of temperature on ionic mobility in mineral and vegetable oil is examined, and their activation energies are calculated. Advancing in the fundamental understanding of the dynamics of the ion transport process in oil‐paper insulation is vital to improving their insulating properties for oil‐impregnated power transformers.

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Investigation of the Space Charge Dynamic in the Nanocomposite BaTiO3 -Doped XLPE

Boumous,

Latreche

et al. 2024

J. Electron. Mater.

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Description of space charge transport in oil‐paper insulation using adaptive time‐stepping transient upstream finite element method

Cited by 7 publications

References 33 publications

Space Charge Behavior in Epoxy‐Based Dielectrics: Progress and Perspective

Space Charge Behavior in Epoxy‐Based Dielectrics: Progress and Perspective

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

Investigation of the Space Charge Dynamic in the Nanocomposite BaTiO3 -Doped XLPE

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