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551 results on '"Lei, Qingquan"'

2. Electric Field Analysis and Insulation Structure Optimization of 66 kV/10 MVA Offshore Wind Power Dry-Type Transformer

Author

Liu, Yuan, Zhang, Sheng, He, Zhiyuan, Pang, Hui, Lei, Qingquan, Fan, Yadong, Angrisani, Leopoldo, Series Editor, Arteaga, Marco, Series Editor, Panigrahi, Bijaya Ketan, Series Editor, Chakraborty, Samarjit, Series Editor, Chen, Jiming, Series Editor, Chen, Shanben, Series Editor, Chen, Tan Kay, Series Editor, Dillmann, Rüdiger, Series Editor, Duan, Haibin, Series Editor, Ferrari, Gianluigi, Series Editor, Ferre, Manuel, Series Editor, Hirche, Sandra, Series Editor, Jabbari, Faryar, Series Editor, Jia, Limin, Series Editor, Kacprzyk, Janusz, Series Editor, Khamis, Alaa, Series Editor, Kroeger, Torsten, Series Editor, Li, Yong, Series Editor, Liang, Qilian, Series Editor, Martín, Ferran, Series Editor, Ming, Tan Cher, Series Editor, Minker, Wolfgang, Series Editor, Misra, Pradeep, Series Editor, Möller, Sebastian, Series Editor, Mukhopadhyay, Subhas, Series Editor, Ning, Cun-Zheng, Series Editor, Nishida, Toyoaki, Series Editor, Oneto, Luca, Series Editor, Pascucci, Federica, Series Editor, Qin, Yong, Series Editor, Seng, Gan Woon, Series Editor, Speidel, Joachim, Series Editor, Veiga, Germano, Series Editor, Wu, Haitao, Series Editor, Zamboni, Walter, Series Editor, Zhang, Junjie James, Series Editor, Yang, Qingxin, editor, Li, Jian, editor, Xie, Kaigui, editor, and Hu, Jianlin, editor

Published
2023
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14. Effect of the cross-linking agent on the cross-linking degree and electrical properties of cross-linked polyethylene

Author

Liu Yujia, Long Yu, Wang Qingyui, Hao Chuncheng, Lei Qingquan, and Guo Xiangjin

Subjects
cross-linking agent, cross-linking degree, breakdown field, partial charge, resistivity, Materials of engineering and construction. Mechanics of materials, TA401-492, Chemical technology, TP1-1185
Abstract

To study the effect of a cross-linking agent on the cross-linking degree and electrical properties of cross-linked polyethylene, different mass fractions of cross-linked polyethylene and their electrical properties were investigated. The cross-linking degree of cross-linked polyethylene with different mass fractions was tested by the extraction method. The breakdown field strength was tested by DC voltage breakdown tester, and the space charge injection of two kinds of cross-linked polyethylene was tested by Pulsed Electro-Acoustic. In addition, the resistivity was measured with conductivity test. The obtained results show that the crossing degree and breakdown field are the highest when the mass fraction of DCP is 2.5 wt% and BIPB is 1.5 wt%, which is 89.39% and approximately 310 kv mm ^−1 , respectively, while the cross-linking degree and breakdown field are 88.28% and approximately 340 kv mm ^−1 , respectively. At the same time, when DCP is used as the cross-linking agent, the amount of the same cross-linking agent is greater, which leads to more impurities contained in the material and increased space charge accumulation in the material; thus, the breakdown strength is lower than that of BIPB, and the conductivity is higher with the cross linking agent of DCP.

Published
2023
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15. Surface trap characteristics of polyimide and effect of surface charge accumulation on surface flashover.

Author

Li, Guochang, Hu, Kai, Sun, Weixin, Wei, Yanhui, Li, Shengtao, and Lei, Qingquan

Subjects
SURFACE charges, SURFACE charging, SURFACE conductivity, FLASHOVER, ELECTRIC fields, SURFACE potential, ELECTRON traps
Abstract

Charge accumulation on the surface of insulation dielectric used in high voltage DC equipment is one of the important causes of surface flashover. Surface charge accumulation is closely related to surface trap characteristics. In this paper, the surface trap energy level distribution of polyimide (PI) was calculated and analyzed by the corona charging method and surface potential decay method. Besides, electron and hole trap characteristics were studied by changing the polarity and amplitude of the charging voltage. Furthermore, the influence of surface charge polarity and quantity on the flashover voltage was researched. Experimental results indicate that the energy level of traps corresponding to the maximum trapped charge density ranges around 0.94 eV. In addition, the energy level of the hole trap is slightly higher than that of the electron trap. The maximum charge density captured by the electron trap and hole trap is about 1.17 × 1021 and 1.03 × 1021 eV−1 m−3, respectively. The polarity of the surface charge can influence the conductivity characteristics of PI, the surface heterocharge reduces the volume conductivity by about 80% while the surface homocharge improves the volume conductivity of PI by about 6.4 times. Besides, both negative and positive surface charges can improve surface conductivity. The polarity of surface charge influences the flashover characteristics of PI, the flashover voltage increases by about 37.8% with the increase of homocharge density and decreases by about 23.8% with the increase of heterocharge density, which is related to the change of electric field near the cathode caused by surface charge accumulation. [ABSTRACT FROM AUTHOR]

Published
2022
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