Epoxy disc-type spacer, as the major insulator of gas insulated transmission line, plays a significant role in the reliability and safety of the entire power grid. While surface charge accumulation on the spacer could induce flashover and accelerate degradation of the insulator, which threats the operation of high-voltage DC transmission and grid. In this study, a corona discharging system was employed to charge the epoxy samples before the charge dissipation measured, and the surface flashover voltages of samples with different modification time under DC voltage were also measured, the results are obtained from the research. It is found that the carrier mobility and surface flashover voltage of samples are affected by modification time, and maximum value of both can be obtained when the sample is modified for 60 min. Under the combined voltages, the initial surface charge density and carrier mobility are affected by both pulse voltage and modification time. It is indicated that surface modification is an appropriate method which can significantly inhibit the surface charge accumulation, and improve the flashover characteristics of epoxy sample by increasing carrier mobility. The trap distribution characteristics suggested that the modification treatment and charging condition have a significant effect on the depth and density of trap.

References

1. 1)
  - 21. Teyssedre, G., Laurent, C.: ‘Charge transport modeling in insulating polymers: from molecular to macroscopic scale’, IEEE Trans. Dielectr. Electr. Insul., 2005, 12, (5), pp. 857–875.
2. 2)
  - 18. Li, C., Hu, J., Lin, C., et al: ‘The control mechanism of surface traps on surface charge behavior in alumina-filled epoxy composites’, J. Phys. D, Appl. Phys., 2016, 49, (44), p. 445304.
3. 3)
  - 24. Saulnier, F., Dubois, M., Charlet, K., et al: ‘Direct fluorination applied to wood flour used as a reinforcement for polymers’, Carbohydr. Polym., 2013, 94, (1), pp. 642–646.
4. 4)
  - 12. Jun, X., Chalmers, I.D.: ‘The influence of surface charge upon flash-over of particle-contaminated insulators in SF6 under impulse-voltage conditions’, J. Phys. D, Appl. Phys., 1997, 30, (30), p. 1055.
5. 5)
  - 8. Du, B.X., Xiao, M.: ‘Influence of surface charge on DC flashover characteristics of epoxy/BN nanocomposites’, IEEE Trans. Dielectr. Electr. Insul., 2014, 21, (2), pp. 529–536.
6. 6)
  - 6. Iwabuchi, H., Matsuoka, S., Kumada, A., et al: ‘Influence of tiny metal particles on charge accumulation phenomena of GIS model spacer in high-pressure SF6 gas’, IEEE Trans. Dielectr. Electr. Insul., 2013, 20, (5), pp. 1895–1901.
7. 7)
  - 10. Du, B.X., Zhang, J.W., Gao, Y.: ‘Effect of nanosecond rise time of pulse voltage on the surface charge of epoxy/TiO2 nanocomposites’, IEEE Trans. Dielectr. Electr. Insul., 2013, 20, (1), pp. 321–328.
8. 8)
  - 22. Zhou, F., Li, J., Yan, Z., et al: ‘Investigation of charge trapping and detrapping dynamics in LDPE, HDPE and XLPE’, IEEE Trans. Dielectr. Electr. Insul., 2017, 23, (6), pp. 3742–3751.
9. 9)
  - 1. Jung, J.J., Cui, S., Sul, S.K.: ‘A new topology of multilevel VSC converter for hybrid HVDC transmission system’, IEEE Applied Power Electronics Conf. and Exposition, 2016, pp. 2620–2628.
10. 10)
  - 13. Du, B.X., Li, J., Du, Q., et al: ‘Surface charge and flashover voltage of EVA/CB nanocomposite under mechanical stresses’, IEEE Trans. Dielectr. Electr. Insul., 2017, 23, (6), pp. 3734–3741.
11. 11)
  - 20. Kharitonov, A.P., Kharitonova, L.N.: ‘Surface modification of polymers by direct fluorination: a convenient approach to improve commercial properties of polymeric articles’, Pure Appl. Chem., 2009, 81, (3), pp. 451–471.
12. 12)
  - 28. Rodrigo, H., Kwag, D., Graber, L., et al: ‘AC flashover voltages along epoxy surfaces in gaseous helium compared to liquid nitrogen and transformer oil’, IEEE Trans. Appl. Supercond., 2014, 24, (3), pp. 1–6.
13. 13)
  - 14. Jiang, Y., An, Z., Liu, C., et al: ‘Influence of oxyfluorination time on space charge behavior in polyethylene’, IEEE Trans. Dielectr. Electr. Insul., 2010, 17, (6), pp. 1814–1823.
14. 14)
  - 4. Ma, G.M., Zhou, H.Y., Li, C.R., et al: ‘Designing epoxy insulators in SF6-filled DC-GIL with simulations of ionic conduction and surface charging’, IEEE Trans. Dielectr. Electr. Insul., 2015, 22, (6), pp. 3312–3320.
15. 15)
  - 25. Kharitonov, A.P., Prorokova, N., Istratkin, V., et al: ‘Improvement of polypropylene nonwoven fabric antibacterial properties by the direct fluorination’, RSC Adv., 2015, 5, (55), pp. 44545–44549.
16. 16)
  - 27. Schein, L.B., Peled, A., Glatz, D.: ‘The electric field dependence of the mobility in molecularly doped polymers’, J. Appl. Phys., 1989, 66, (2), pp. 686–692.
17. 17)
  - 17. Du, B.X., Li, Z.L., Li, J.: ‘Surface charge accumulation and decay of direct-fluorinated RTV silicone rubber’, IEEE Trans. Dielectr. Electr. Insul., 2014, 21, (5), pp. 2338–2342.
18. 18)
  - 9. Srivastava, K.D., Zhou, J.: ‘Surface charging and flashover of spacers in SF6 under impulse voltages’, IEEE Trans. Dielectr. Electr. Insul., 1991, 26, (3), pp. 428–442.
19. 19)
  - 19. Simmons, J.G., Tam, M.C.: ‘Theory of isothermal currents and the direct determination of trap parameters in semiconductors and insulators containing arbitrary trap distributions’, Phys. Rev. B, 1973, 7, (8), pp. 3706–3713.
20. 20)
  - 15. Li, C., He, J., Hu, J.: ‘Surface morphology and electrical characteristics of direct fluorinated epoxy-resin/alumina composite’, IEEE Trans. Dielectr. Electr. Insul., 2016, 23, (5), pp. 3071–3077.
21. 21)
  - 26. Matsuoka, N., Fuchi, Y., Kozako, M., et al: ‘Effect of permittivity variation on surface flashover of GIS epoxy spacer model in SF6 gas’, IEEE Int. Conf. on Dielectrics, 2016, pp. 96–99.
22. 22)
  - 16. An, Z., Yin, Q., Liu, Y., et al: ‘Modulation of surface electrical properties of epoxy resin insulator by changing fluorination temperature and time’, IEEE Trans. Dielectr. Electr. Insul., 2015, 22, (1), pp. 526–534.
23. 23)
  - 2. Feltes, J.W., Gemmell, B.D., Retzmann, D.: ‘From smart grid to super grid: solutions with HVDC and FACTS for grid access of renewable energy sources’, IEEE Power and Energy Society General Meeting, 2011, pp. 1–6.
24. 24)
  - 7. Mansour, D.E. A., Kojima, H., Hayakawa, N., et al: ‘Surface charge accumulation and partial discharge activity for small gaps of electrode/epoxy interface in SF6 gas’, IEEE Trans. Dielectr. Electr. Insul., 2009, 16, (4), pp. 1150–1157.
25. 25)
  - 3. Hama, H., Okabe, S.: ‘Cross-sectional study between SF6 and eco-friendly gases on dielectric coated electrodes for real-size gas insulated switchgear’, IEEE Trans. Dielectr. Electr. Insul., 2012, 19, (1), pp. 253–262.
26. 26)
  - 23. Perlman, M.M., Sonnonstine, T.J., St. Pierre, J.A.: ‘Drift mobility determinations using surface-potential decay in insulators’, J. Appl. Phys., 1976, 47, (11), pp. 5016–5021.
27. 27)
  - 5. Miller, H.C.: ‘Surface flashover of insulators’, IEEE Trans. Dielectr. Electr. Insul., 1988, 24, (5), pp. 765–786.
28. 28)
  - 11. Kumara, S., Serdyuk, Y.V., Gubanski, S.M.: ‘Simulation of surface charge effect on impulse flashover characteristics of outdoor polymeric insulators’, IEEE Trans. Dielectr. Electr. Insul., 2010, 17, (6), pp. 1754–1763.

Carrier mobility and trap distribution dependent flashover characteristics of epoxy resin

References

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