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Advances in Electric Charge Behavior Modulated Insulation Performance in High Voltage Power Equipment

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A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "F: Electrical Engineering".

Deadline for manuscript submissions: closed (31 July 2023) | Viewed by 10046

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Dr. Yu Gao

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Guest Editor

School of Electrical Automation and Information Engineering, Tianjin University, Tianjin 300072, China
Interests: ageing of polymer insulating material used under radioactive environment; nano-dielectrics; condition monitoring; diagnosis of power equipment
Special Issues, Collections and Topics in MDPI journals

Dr. Zhonglei Li

E-Mail Website
Guest Editor

School of Electrical Automation and Information Engineering, Tianjin University, Tianjin 300072, China
Interests: advanced insulating materials for power cables and accessories; condition assessment; multiphysics simulation technologies for cable systems
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

With the development of the electrical power industry, the enhancement in voltage level yields new challenges to insulation of high voltage power equipment. Such challenges become even more remarkable as the compactness and the miniaturization of the equipment are required by power consumers. Accordingly, insulation safety plays a very important role in the reliable service of the equipment. Electric charges appearing in insulating material or at the material surface have been recognized as a critical reason for electric field distortion which triggers insulation breakdown failure. Understanding of the charge behaviour is thereby essential for the design and the ageing evaluation of insulation installed in the equipment. Over the past 40 years, the progresses of measuring techniques have enabled researchers the in-depth investigation of the charge dynamic behaviour and its related insulation performance. This Special Issue aims to present the most recent advances in electric charge related studies including measuring technique, theory, modelling, design and especially its role in modulating the performance of insulating materials.

Topics of interest for publication include, but are not limited to:

Measuring techniques of electric charges in gas, liquid, or solid insulating materials.
Phenomenon and modelling of electric charge dynamic behaviour in gas, liquid, or solid insulating materials.
Electric charge modulated dielectric breakdown behaviour at insulating materials.
Space charge or interface charge within cable insulation systems.
Surface charge accumulation and decay on spacers installed in Gas Insulated Switchgear (GIS) and/or Gas Insulated Transmission Line (GIL).
Charge dynamics at oil–paper interfaces with oil-impregnated paper insulation.
Charge implant and decay in solid dielectrics used in aerospace environments with energetic radiation.
Breakdown of gas, liquid, or solid insulating materials.
Method and strategy to control the charge and improve insulation performance.

Dr. Yu Gao
Dr. Zhonglei Li
Guest Editors

Manuscript Submission Information

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Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

space charge
surface charge
interface charge
insulation performance
cable insulation
carrier trap
spacer
deep dielectric charging
flashover
suppression
breakdown
nanodielectrics

Published Papers (7 papers)

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Research

14 pages, 4720 KiB

Open AccessArticle

Improved Locating Method for Local Defects in XLPE Cable Based on Broadband Impedance Spectrum

by Liqiang Wei, Xianhai Pang, Jingang Su, Tao Han and Yufei Yao

Energies 2022, 15(21), 8295; https://0-doi-org.brum.beds.ac.uk/10.3390/en15218295 - 06 Nov 2022

Cited by 2 | Viewed by 1185

Abstract

The crosslinked polyethylene (XLPE) cable safety is affected by environmental factors and artificial defects during operation. This work proposes an improved locating method based on broadband impedance spectrum (BIS) to locate local defects in XLPE cables. The calculation process of the algorithm has been analyzed. The selection of the incident Gaussian signal and the peak recognition method have been discussed, where the pulse width of the Gaussian signal was found to be determined primarily by the upper limit frequency of the traveling wave transmitting in the cable. The centroid and function fitting methods were established to reduce the peak recognition error caused by the test sampling rate. This work verified the accuracy of the algorithm through experiments. A vector network analyzer (VNA) was used to test the BIS of the cable. A 20 m-long cable containing abrasion and an inserted nail with different depths was measured in the BIS test. It was found that the abrasion and the nail could be located. The locating deviation of abrasion was within ±1%, and the centroid and function fitting methods could effectively reduce the locating deviation. The locating deviation was within ±1% when the depth of the nail inserted into the cable accounted for less than 50% of the insulation thickness. When the depth exceeded 75% of the insulation thickness, the deviation of each method was more significant, and the maximum absolute value of the deviation was 4%. Full article

(This article belongs to the Special Issue Advances in Electric Charge Behavior Modulated Insulation Performance in High Voltage Power Equipment)

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18 pages, 7150 KiB

Open AccessArticle

Validation through Experiment and Simulation of Internal Charging–Discharging Characteristics of Polyimide under High-Energy Electron Radiation

by Jiang Wu, Bo Zhang, Yibo Zhi, Minheng He, Penghui Shang and Yufeng Qian

Energies 2022, 15(18), 6603; https://0-doi-org.brum.beds.ac.uk/10.3390/en15186603 - 09 Sep 2022

Viewed by 1046

Abstract

Due to the injection of energetic particles, such as electrons in space environment, the internal charging–discharging characteristics of spacecraft dielectrics need to be evaluated for the safety of spacecraft, and the evaluation results from experiments and simulations should be comparatively validated. An in-site pulsed electroacoustic (PEA) measurement system under high-energy electron radiation was established for evaluating the charging characteristics of thick plate samples about 3 mm, while a joint simulation method based on Geant4 and COMSOL was also proposed. The deposited charge distributions were compared through experiment and joint simulation method under 0.7, 1.0 and 1.3 MeV for 30 min and 1.0 MeV for 10, 60 and 120 min, respectively. Meanwhile, the electrostatic discharging characteristics were also comparative evaluated by both methods under 0.3 MeV for 20 min under 5, 10 and 15 µA beam current, and the total discharging times and initial discharging time were compared and analyzed. Overall, a good consistency existed between experimental and simulation results of charging–discharging characteristics under electron radiation while the difference was also analyzed in the perspective of dielectric properties, such as charge leakage by conduction. Through the comparative study, both evaluation methods are validated, which offers effective reference for the safety evaluation of spacecraft dielectrics in future. Full article

(This article belongs to the Special Issue Advances in Electric Charge Behavior Modulated Insulation Performance in High Voltage Power Equipment)

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14 pages, 7067 KiB

Open AccessArticle

Properties and Simulating Research of Epoxy Resin/Micron-SiC/Nano-SiO₂ Composite

by Ning Guo, Ruixiao Meng, Junguo Gao, Mingpeng He, Yue Zhang, Lizhi He and Haitao Hu

Energies 2022, 15(13), 4821; https://0-doi-org.brum.beds.ac.uk/10.3390/en15134821 - 01 Jul 2022

Viewed by 1391

Abstract

The dielectric behavior of insulations is a key factor affecting the development of anti-corona materials for generators. Epoxy resin (EP), as the matrix, is blended with inorganic fillers of micron SiC and nano SiO₂ to investigate the effect of micro and nano doping on the conductivity and breakdown mechanism of the composites. Using experimental and simulation analysis, it is found that the effect of nano-SiO₂ doping concentration on the conductivity is related to the dispersion of SiC particles. The lower concentration of SiO₂ could decrease the conductivity of the composites. The conductivity increases with raising the nano-SiO₂ doping concentration to a critical value. Meanwhile, the breakdown field strength of the composites decreases with the rising content of SiC in constant SiO₂ and increases with more SiO₂ when mixed with invariable SiC. When an equivalent electric field is applied to the samples, the electric field at the interface of micron particles is much stronger than the average field of the dielectric, close to the critical electric field of the tunneling effect. The density of the homopolar space charge bound to the surface of the stator bar elevates as the concentration of filled nanoparticles increases, by which a more effective Coulomb potential shield can be built to inhibit the further injection of carriers from the electrode to the interior of the anti-corona layer, thus reducing the space charge accumulation in the anti-corona layer as well as increasing the breakdown field strength of the dielectric. Full article

(This article belongs to the Special Issue Advances in Electric Charge Behavior Modulated Insulation Performance in High Voltage Power Equipment)

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13 pages, 6158 KiB

Open AccessArticle

The Effect of a Metal Particle on Surface Charge Accumulation Behavior of Epoxy Insulator with Zoning Coating

by Wenqu Wang, Yu Gao and Huicun Zhao

Energies 2022, 15(13), 4730; https://0-doi-org.brum.beds.ac.uk/10.3390/en15134730 - 28 Jun 2022

Cited by 3 | Viewed by 1287

Abstract

Epoxy insulators are widely used in Gas-Insulated Transmission Lines (GILs), playing a significant role in electrical insulation and mechanical support. The metal particles generated during the production and operation of the equipment aggravate surface charge accumulation on the insulator, causing surface flashover. Therefore, it is necessary to study the suppression strategy of charge accumulation. In this paper, a downsized disc insulator was taken as the research object to investigate the effect of zoning coating on charge suppression with the presence of a linear aluminum metal particle under negative DC voltage. The zoning coating method was achieved by painting coatings with different conductivities in three areas on the insulator surface to regulate the charge. The inhibition mechanism of zoning coating on the charge accumulation in the presence of a linear metal particle was analyzed with the assistance of numerical simulation. The results showed that negative charges were accumulated in the nonplanar region as there was no metal particle, and the existence of metal particles led to the significant accumulation of positive charge speckles in the nonplanar region. The application of zoning coating could significantly inhibit the charge accumulation in the nonplanar area of the insulator and the charge injection from the grounded electrode to reduce the charge density. Under −25 kV, the maximum charge density on the insulator with the zoning coating was 48.1% lower than that without the coating, and the inhibition effect increased by 57.9% when the metal particle was introduced. This paper provides a new way to suppress the charge accumulation on the insulator surface. Full article

(This article belongs to the Special Issue Advances in Electric Charge Behavior Modulated Insulation Performance in High Voltage Power Equipment)

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15 pages, 2584 KiB

Open AccessArticle

Surface Flashover Characteristics of Epoxy Resin Composites in SF₆/CF₄ Gas Mixture with DC Voltage

by Xin Wang, Zhimin Wang, Jieyuan Chen, Xiaofei Shi and Xiaolong Li

Energies 2022, 15(13), 4675; https://0-doi-org.brum.beds.ac.uk/10.3390/en15134675 - 25 Jun 2022

Cited by 2 | Viewed by 1347

Abstract

SF₆/CF₄ mixture is considered a potential substitution for SF₆ in gas-insulated equipment owing to the considerable insulation and low temperature characteristics of CF₄. This paper concerns the substitutability of the mixture on the surface flashover property. Epoxy resin composites for solid insulators are applied since flashover at the insulator interface often occurs and results in severe damage to the safe operation of the equipment. Two kinds of electrode systems are designed to study DC flashover properties with different electric field uniformities. The obtained result shows that the flashover voltage in the 20% SF₆/80% CF₄ mixture achieved more than 70% of the voltage in SF₆ at the same pressure. The mixture shows considerable synergy in the surface flashover process and performed different tendencies with varying gas pressures and contents under different electrode systems due to the influence of surface accumulated charge. Moreover, it is considered that surface charge due to ionization may result in a reversal phenomenon for voltage polarity with increasing pressure. The results indicate the possibility of SF₆/CF₄ functioning as an efficient substitution of SF₆ with a considerable insulation property and improved environmental protection characteristics. Full article

(This article belongs to the Special Issue Advances in Electric Charge Behavior Modulated Insulation Performance in High Voltage Power Equipment)

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11 pages, 6058 KiB

Open AccessArticle

Influence of Space Charge on Dielectric Property and Breakdown Strength of Polypropylene Dielectrics under Strong Electric Field

by Zhaoliang Xing, Zhenlu Gu, Chong Zhang, Shaowei Guo, Huize Cui, Qingquan Lei and Guochang Li

Energies 2022, 15(12), 4412; https://0-doi-org.brum.beds.ac.uk/10.3390/en15124412 - 17 Jun 2022

Cited by 5 | Viewed by 1691

Abstract

Space charge accumulation in polypropylene (PP) affect the dielectric properties and breakdown strength of the material. The pre-injected charge in PP under the action of different polarity voltage is quantitatively characterized, and the effects of the pre-injected charge inside the dielectric on the dielectric properties and breakdown strength are measured and analyzed. Based on the molecular simulations, the influence mechanism of the temperature on dielectric properties and breakdown are discussed. The experimental results show that the injected charges in PP under the negative polarity voltage is significantly larger than that of the positive polarity. These charges have a great influence on the dielectric constant and breakdown performance of PP, and the effect is different for different charge polarity. The effect of negative polarity pre-voltage conditions on the dielectric constant is much greater than that of positive polarity, and the dielectric constant of PP decreases from 2.2 to 1.3, decreasing about 41% under the negative polarity pre-voltage. By contrast, the dielectric constant slightly increases under the effect of the homopolar preload. Furthermore, the breakdown strength of the dielectric after the heteropolar preload is 249 kV/mm, which is 36% lower than that of PP without pre-voltage, and it slightly increases after the positive polarity pre-voltage. As the temperature increases, the increase in free volume favors the development of electron collision ionization and electron collapse processes, leading to a decrease in breakdown voltage at high temperatures. This work has a good guiding significance for the comprehensive evaluation of energy storage parameters. Full article

(This article belongs to the Special Issue Advances in Electric Charge Behavior Modulated Insulation Performance in High Voltage Power Equipment)

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10 pages, 3029 KiB

Open AccessArticle

Study on the Influence of Organic–Inorganic Interface Properties on Breakdown Strength and Thermal Properties of MgO/PLA Composites

by Rongguo Huang, Jia Feng, Chunguang Lu, Bin Du and Jianyu Ding

Energies 2022, 15(10), 3479; https://0-doi-org.brum.beds.ac.uk/10.3390/en15103479 - 10 May 2022

Viewed by 1149

Abstract

Polylactic acid (PLA) is expected to be widely used in green power equipment manufacturing due to its good mechanical properties and biodegradability. In this paper, the effects of MgO with different particle sizes and mass fractions on the thermal and electrical properties of PLA composites were studied. The experiment found that with the increase in MgO particle sizes and mass fractions, the thermal conductivity of MgO/PLA composites showed a rising trend, which was up to 165.4% higher than that of pure PLA. However, the heat resistance first increases and then decreases. For the electrical properties of MgO/PLA composites, the breakdown strength and volume resistivity decrease with an increase in MgO particle size and mass fraction. In order to further study the influence mechanism of the introduction of MgO with different particle sizes and mass fractions on the thermal and electrical properties of MgO/PLA composites, molecular dynamics simulation was used to simulate the glass transition temperature (Tg) of PLA composites doped with MgO of different particle sizes, and it was found that MgO doping weakened the movement of the PLA molecular chain segment. Using density functional theory (DFT) calculations, it was found that in the MgO and PLA system, electrons have a tendency to migrate from the PLA matrix to MgO, which causes the formation of electron traps at the inorganic–organic interface and affects its electrical properties. The purpose of this study is to provide a theoretical reference for PLA composites in the manufacture of power equipment. Full article

(This article belongs to the Special Issue Advances in Electric Charge Behavior Modulated Insulation Performance in High Voltage Power Equipment)

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