Surface forward and backward discharges and corresponding residual charge accumulation characteristics under positive impulse

Chen, Junhong; Li, Jinshu; Dong, Junhao; Sun, Peng; Xue, Jie; Deng, Junbo; Zhang, Guanjun

doi:10.1063/5.0077542

Cited by 17 publications

(13 citation statements)

References 48 publications

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“…In GIL, spacers are key components serving as mechanical support and electrical insulation. The spacers and the surrounded gas which may be SF 6 gas or other environmental friendly gas mixtures constitute the insulation system in GIL [3,4]. The resulted gas-solid interface becomes the most vulnerable link in the compound insulation system.…”

Section: Introductionmentioning

confidence: 99%

“…The resulted gas–solid interface becomes the most vulnerable link in the compound insulation system. The long‐term DC excitation enables the spacer surface to accumulate plenty of charges, which may distort the surface electric field and then destroy the safety of the gas–solid interface insulation [5]. The proper surface modification strategies are necessary for releasing surface charges and guarding the reliability of gas–solid interface insulation.…”

Section: Introductionmentioning

confidence: 99%

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Temperature‐dependent adaptive conductivity coating for surface charge release and electric field control under electro‐thermal coupling field

Xue

Zhang

et al. 2023

High Voltage

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Surface charge accumulation is the potential criminal for surface insulation failure on spacers under direct current (DC) voltages. The existence of thermal gradient posing the difficulty of surface charge regulation. This study proposes a temperature‐dependent adaptive conductivity coating technique for surppressing surface charge accumulation under electro‐thermal coupling field. A two‐dimensional axis‐symmetrical simulation model regrading surface charge computation is established. The effects of thermal gradients and coating conductivity on surface charge and electric field distribution are investigated. The results show that the thermal gradient increases the bulk conductive current, therefore aggravating surface charge accumulation. The effects of the coating condcutivity on surface charge and electric field contains three stages. The lower coating conductivity leads to aggravated homo‐polarity charge accumulation. By increasing the coating conductivity, the surface charge and electric field are significantly suppressed at the obtained optimal conductivity, where the bulk and surface conductive current reach a balance stage. Continuously increasing the coating conductivity results in aggravated hetero‐polarity charges. Besides, the increase of thermal gradient to an appropriate extent contributes to the further suppression of surface charge on coated spacers. It is hoped that this study could provide some references for designing highly reliable DC GIL under electro‐thermal coupling field.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Temperature‐dependent adaptive conductivity coating for surface charge release and electric field control under electro‐thermal coupling field

Xue

Zhang

et al. 2023

High Voltage

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“…While the energy gap between the surface layers, charge transport, and polarization was suggested in electron triggered polarity relaxation (ETPR) [13]. Additionally, the comprehensive analytic models were discussed in the compressed gas insulated systems [14][15][16], including the surface flashover mechanism under high pressure, the charge migration due to the injection of conductors, space charge migration, and trapping on the surface. For DC high voltage systems, in particular, surface charging and surface trapping are considered to be the dominant factors that strongly affect the surface flashover voltage [17], while for AC voltage, the polarity of the surface charge is closely related to the truncated phase of AC voltage [18].…”

Section: Introductionmentioning

confidence: 99%

The surface flashover process under positive lightning impulse voltage: initial stage and evolution

Yang¹,

Xue²,

Deng³

et al. 2022

J. Phys. D: Appl. Phys.

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Surface flashover is a crucial issue in the field of electrical insulation, and it involves many complex physical processes. In this paper, the development process of the surface flashover was studied from different methods. The initial process of positive surface streamers in different gas environments (air, N2, CO2) was studied by photoelectric observation. The evolution of positive surface streamers in the air was described based on a 2D fluid model. The influence of the surface trap energy level on flashover development and the relationship between gas adsorption and surface trap energy level was discussed by density functional theory calculation preliminarily. The results showed that the initial ionization process of surface flashover is considered as the collision ionization between the initial electrons and gas molecules and photoionization of high-energy photons. Some of the high-energy photons can not only ionize some gas molecules but also cause the surface of the insulator to emit electrons (photoemission process), which could promote the development of the streamer. Both the ionization of the gas molecules and the photoelectric emission of the insulator surface may determine the initial development of surface flashover. During the process of the flashover, the electron density of the surface streamer (∼1021 m−3) is high and the main streamer tends to develop towards the insulator surface. The attraction of surface streamers changes with the position of the initial electron, and the positive surface charge brings the stronger ionization process, and the negative surface charge has the opposite effect. The band gap of the insulator surface is affected by the adsorption of gas molecules, which is considered as introducing shallow traps on the surface. For impulse voltage, the charge accumulation and internal charge migration may be not evident, the initial photoionization process and initial surface charge distribution affect the flashover process primarily.

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“…Due to their excellent dielectric properties, polymeric insulation materials have been widely used in electronic and electrical equipment, , such as electrical cables, energy storage capacitors, insulators, and transformers. Charge migration in polymeric insulation under a high electric field can lead to electrical aging and even failure of electronic and electrical devices. , To clarify the electrical aging mechanism and further improve the performance of polymeric insulation, it is of great significance to establish a charge transport model and quantitatively characterize the charge transport properties of polymeric dielectrics.…”

Section: Introductionmentioning

confidence: 99%

“…Charge migration in polymeric insulation under a high electric field can lead to electrical aging and even failure of electronic and electrical devices. 3,4 To clarify the electrical aging mechanism and further improve the performance of polymeric insulation, it is of great significance to establish a charge transport model and quantitatively characterize the charge transport properties of polymeric dielectrics.…”

Section: Introductionmentioning

confidence: 99%

Multiscale Study of the Charge Transport Properties of Silicone Rubber Oligomers

et al. 2022

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Polymer dielectrics are widely used as insulation in electronic and electrical equipment. The charge transport process in polymer dielectrics under a high electric field, which is considered to result in electrical aging and even breakdown of equipment insulation, has attracted considerable attention. Based on a localized charge transfer model, the charge transport mechanism for typical silicone rubber (SR) insulating materials was studied by multiscale methods. A model of silicone rubber oligomers under standard conditions was generated by classical molecular dynamics. The frontier molecular orbitals and projected density of states for the SR oligomer were obtained via quantum chemistry methods. The electronic coupling, reorganization energy, and free energy difference for both electron and hole transfer processes between adjacent SR molecules in the molecular dynamics model were calculated. Both hole transfer and electron transfer in SR conform to an intermolecular hopping mechanism due to their high intramolecular reorganization energy and low intermolecular electronic coupling. The results of normal mode analysis for reorganization energy indicate that the high-temperature approximation holds for charge transport in SR around or above room temperature. The charge transfer trajectory and charge mobility in SR were simulated based on kinetic Monte Carlo simulations. The hole and electron mobilities at room temperature were calculated to be 7.24 × 10 −11 and 2.76 × 10 −9 cm 2 /Vs, respectively, which agrees with the experimental data. Both electron transport and hole transport in SR show thermal activation characteristics, with corresponding activation energies of 358 and 314 meV, respectively. This work suggests a physical model to describe the charge transport process in SR polymer dielectrics.

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Surface forward and backward discharges and corresponding residual charge accumulation characteristics under positive impulse

Cited by 17 publications

References 48 publications

Temperature‐dependent adaptive conductivity coating for surface charge release and electric field control under electro‐thermal coupling field

Temperature‐dependent adaptive conductivity coating for surface charge release and electric field control under electro‐thermal coupling field

The surface flashover process under positive lightning impulse voltage: initial stage and evolution

Multiscale Study of the Charge Transport Properties of Silicone Rubber Oligomers

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