Space Charge Behavior of Oil-Impregnated Paper Insulation Aging at AC-DC Combined Voltages

  • Li, Jian ;
  • Wang, Yan ;
  • Bao, Lianwei
  • Received : 2013.07.09
  • Accepted : 2013.10.14
  • Published : 2014.03.01


The space charge behaviors of oil-paper insulation affect the stability and security of oil-filled converter transformers of traditional and new energies. This paper presents the results of the electrical aging of oil-impregnated paper under AC-DC combined voltages by the pulsed electro-acoustic technique. Data mining and feature extractions were performed on the influence of electrical aging on charge dynamics based on the experiment results in the first stage. Characteristic parameters such as total charge injection and apparent charge mobility were calculated. The influences of electrical aging on the trap energy distribution of an oil-paper insulation system were analyzed and discussed. Longer electrical aging time would increase the depth and energy density of charge trap, which decelerates the apparent charge mobility and increases the probability of hot electron formation. This mechanism would accelerate damage to the cellulose and the formation of discharge channels, enhance the acceleration of the electric field distortion, and shorten insulation lifetime under AC-DC combined voltages.


Oil-paper insulation;Electrical aging;Space charge;PEA;Trap;Apparent charge mobility


  1. W. X. Lu and B.T. Ooi, "Optimal Acquisition and Aggregation of Offshore Wind Power by Multiterminal Voltage-Source HVDC", IEEE Trans. Power Delivery, vol. 18, no. 1, pp.201-206, Jan. 2003.
  2. CIGRE Joint Task Force B4.04/A2-1, "Analysis of HVDC Thyristor Converter Transformer Performance," in Proceedings of Council on Large Electric Systems, Canada, Feb. 2004.
  3. W. Choo, G. Chen and S. G. Swingler, "Electric Field in Polymeric Cable Due to Space Charge Accumulation under DC and Temperature Gradient," IEEE Trans. Dielectr. Electr. Insul., vol.18, no.2, pp.596-606, April 2011.
  4. Y. Wang, J. Li, Y. Y. Wang, S. Grzybowski, "Electrical breakdown properties of oil-paper insulation under AC-DC combined voltages," in Proceedings of IEEE Conf. Power Modulator and High Voltage, Atlanta, America, May 2010.
  5. G. Mazzanti, G. C. Montanari and J. M. Alison, "A space-charge based method for the estimation of apparent mobility and trap depth as markers for insulation degradation-theoretical basis and experimental validation," IEEE Trans. Dielectr. Electr. Insul., vol. 10, no.2,pp.187-197, April 2003.
  6. G. Chen, Y. Tanaka, T. Takada and L. Zhong, "Effect of polyethylene interface on space charge formation," IEEE Trans. Dielectr. Electr. Insul., vol.11, no.1, pp. 113-121, Feb. 2004.
  7. Montanari G. C., "Dielectric material properties investigated through space charge measurement," IEEE Trans. Dielectr. Electr. Insul., vol.11, no.1, pp. 56-64, Feb. 2004.
  8. Mazzanti G, Montanari G C. "Quantities extracted from space-charge measurements as markers for insulation aging," IEEE Trans. Dielectr. Electr. Insul., vol. 10, no.2, pp.198-203, April 2003.
  9. R. S. Liu, Jaksts A., Tornkvist C., Bergkvist M., "Moisture and space charge in oil-impregnated pressboard under HVDC," in Proceedings of the 6th IEEE Conference on Conduction and Breakdown in Solid Dielectrics, Vasteras, Sweden, June 1998.
  10. R. Ciobanu, I. Prisecaru, and S. Aradoaei, "PEA measurements upon cellulose materials submitted to gamma radiation," in Proceedings of the 8th International Conference on Solid Dielectrics, Toulouse, France, July 2004.
  11. Jian Hao, George Chen, Ruijin Liao, Lijun Yang and Chao Tang, "Influence of Moisture on Space Charge Dynamics in Multilayer Oil-paper Insulation," IEEE Trans. Dielectr. Electr. Insul., vol. 19, no.4, pp.1456- 1464, Mar. 2012.
  12. C. Tang, R.J. Liao, G. Chen, L.J.Yang, "Research on the feature extraction of DC space charge behavior of oil-paper insulation," SCIENCE CHINA-Technological Sciences, vol.54 no.5, pp.1315-1324, May 2011.
  13. Chao Tang, George Chen, Ming Fu, RuiJin Liao, "Space charge behavior in multi-layer oil-paper insulation under different DC voltages and temperatures," IEEE Trans. Dielectr. Electr. Insul., vol.17, no.3,pp.775-784, Aug. 2010.
  14. Mahmoud Abou Dakka, Alexander Bulinski and Soli Bamji, "Space Charge Development and Breakdown in XLPE under DC Field," IEEE Trans. Dielectr. Electr. Insul., vol.11,no.1,pp.41-49, Feb. 2004.
  15. S. Q. Wang, G. J. Zhang, H. B. Mu, D. Wang, M. Lei, Y. Tanaka, et al., "Effects of paper-aged state on space charge characteristics in oil-impregnated paper insulation," IEEE Trans. Dielectr. Electr. Insul., vol. 19, no.6, pp.1871-1878, Dec. 2012.
  16. S. Q. Wang, G. J. Zhang, J. L. Wei, S. S. Yang, M. Dong, and X. B. Huang, "Investigation on dielectric response characteristics of thermally aged insulating pressboard in vacuum and oil-impregnated ambient," IEEE Trans. Dielectr. Electr. Insul., vol. 17, no. 6, pp. 1853-1862, Dec. 2010.
  17. G. C. Montanari, "Bringing an insulation to failure: the role of space charge," IEEE Trans. Dielectr. Electr. Insul., vol. 18, no.2, pp.339-364, April 2011.
  18. Xu Zhi Qiang. Space charge measurement and analysis in low density polyethylene film [D] Southampton: University of Southampton, 2009.
  19. X. Wang, S. Q. Chen, X. Cheng, D. M. Tu, "Measuring energy distribution of surface trap in polymer insulation by PEA method," Proceedings of the CSEE, vol.29, no.1, pp.127-132, Jan. 2009.
  20. B. T. Yang, T. Demin, and Y. N. Liu "Theory of isothermal charge and direct determination of trap distributions in solid dielectrics," Journal of Applied Sciences, vol. 10, no.3, pp. 233-240, Mar. 1992. (in Chinese)
  21. Y. Yin, D. M. Tu, M. Li, and Z. H. Li, "Study on the action mechanism of the free redical scavenger with isothermal current-decay method: an experimental verification of trap theory for electrica aging in polymer," Proceedings of the CSEE, vol. 20, no.3, pp. 13-15, Mar. 2000.
  22. W.J. Zao, High Voltage Direct Current Transmission Engineering Technology, 2nd ed., Peking: China Electric Power Press, 2011, pp.308-309. (in Chinese)
  23. IEC 60243-1, "Electrical Strength of Insulating Materials - Test Methods - Part 1: Tests at Power Frequencies," IEC Publication, 1998.
  24. G. Chen, M. Fu, X. Z. Liu and L. S. Zhong, "Ac aging and space-charge characteristics in low-density polyethylene polymeric insulation," Journal of Applied Physics, vol.97, no.8, pp.083713-0-83713-7, April 2005.
  25. K. C. Kao, "New theory of electrical discharge and breakdown in low - mobility condensed insulators," Journal of applied physics, vol. 55, no.3, pp. 752-755, Sept. 1984.

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