# Analysis on Temperature Distribution and Current-Carrying Capacity of GIL Filled with Fluoronitriles-CO2 Gas Mixture

• Chen, Geng (State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University) ;
• Tu, Youping (State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University) ;
• Wang, Cong (Beijing Key Laboratory of High Voltage & EMC, North China Electric Power University) ;
• Cheng, Yi (State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University) ;
• Jiang, Han (State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University) ;
• Zhou, Hongyang (State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University) ;
• Jin, Hua (School of Control and Computer Engineering, North China Electric Power University)
• Accepted : 2018.04.25
• Published : 2018.11.01

#### Abstract

Fluoronitriles-$CO_2$ gas mixtures are promising alternatives to $SF_6$ in environmentally-friendly gas-insulated transmission lines (GILs). Insulating gas heat transfer characteristics are of major significance for the current-carrying capacity design and operational state monitoring of GILs. In this paper, a three-dimensional calculation model was established for a GIL using the thermal-fluid coupled finite element method. The calculated results showed close agreement with experimentally measured data. The temperature distribution of a GIL filled with the Fluoronitriles-$CO_2$ mixture was obtained and compared with those of GILs filled with $CO_2$ and $SF_6$. Furthermore, the effects of the mixture ratio of the component gases and the gas pressure on the temperature rise and current-carrying capacity of the GIL were analyzed. Results indicated that the heat transfer performance of the Fluoronitriles-$CO_2$ gas mixture was better than that of $CO_2$ but worse than that of $SF_6$. When compared with $SF_6$, use of the Fluoronitriles-$CO_2$ gas mixture caused a reduction in the GIL's current-carrying capacity. In addition, increasing the Fluoronitriles gas component ratio or increasing the pressure of the insulating gas mixture could improve the heat dissipation and current-carrying capacity of the GIL. These research results can be used to design environmentally-friendly GILs containing Fluoronitriles-$CO_2$ gas mixtures.

#### Acknowledgement

Supported by : Central Universities

#### References

1. Y. Kieffel, A. Girodet, F. Biquez, Ph. Ponchon, J. Owens, M. Costello, M. Bulinski, R. Van San, K. Werner, "SF6 alternative development for high voltage switchgear," in Electrical Insulation Conference, 2015, pp. 379-383.
2. H. Koch, Gas-insulated Transmission Lines (GIL). USA: A John Wiley & Sons, Ltd. 2012, pp. 1-5.
3. J. L. He, "Ideas on building underground energy complex passage," Southern Power System Technology, vol. 10, no. 3, pp. 66-70, Mar. 2016. (in Chinese)
4. M. Khalifaed, High Voltage Engineering. New York: Marcel Dekker, Inc., 1990.
5. H. Sadakuni, K. Sasamori, H. Hama, and K. Inami, "Insulation and current carrying design for GIS," Japan Inst. Elec. Eng., vol. 9, pp. 33-42, Mar. 1996.
6. Y. Kieffel, Todd Irwin, Ph. Ponchon, J. Owens, "Green gas to replace SF6 in electrical grids," IEEE Power Energy Mag., vol. 14, pp. 32-39, Apr. 2016.
7. D. Gautschi, A. Ficheux, M. Walter, J. Vuachet, "Application of a fluoronitrile gas in GIS and GIL as an environmental friendly alternative to SF6," in CIGRE, 2016, pp. 1-11.
8. M. Ghassemi, M. Farzaneh. "Coupled computational fluid dynamics and heat transfer modeling of the effects of wind speed and direction on temperature increase of an ice-covered FRP live-line tool," IEEE Trans. Power Del., vol. 30, no. 5, pp. 2268-2275, Oct. 2015. https://doi.org/10.1109/TPWRD.2015.2403267
9. M. T. Dhotre, J. Korbel, X. Ye, J. Ostrowski, S. Kotilainen and M. Kriegel. "CFD simulation of temperature rise in high-voltage circuit breakers", IEEE Trans. Power Del., vol. 32, no. 6, pp. 2530-2536, Dec. 2017. https://doi.org/10.1109/TPWRD.2017.2676841
10. D. Minaguchi, M. Ginno, K. Itaka, et al. "Heat transfer characteristics of gas-insulated transmission lines," IEEE Trans. Power Del., vol. 1, no. 1, pp. 1-9, Jan. 1986. https://doi.org/10.1109/TPWRD.1986.4307881
11. H. Koch, A. Chakir, "Thermal calculationa for buried gas-insulated transmission lines (GIL) and XLPECable," in Power Engineering Society Winter Meeting, 2001, pp. 857-862.
12. R. Benato, F. Dughiero, "Solution of coupled electromagnetic and thermal problems in gas-insulated transmission Lines," IEEE Trans. Magn., vol. 39, no. 3, pp. 1741-1744, May. 2003. https://doi.org/10.1109/TMAG.2003.810393
13. J. K. Kim, S. C. Hahn, K Y Park, H. K. Kim, Y. H. Oh, "Temprature rise prediction of EHV GIS bus bar by coupled magnetothermal finite element method," IEEE Trans. Magn., vol. 41, no. 5, pp. 1636-1639, May. 2005. https://doi.org/10.1109/TMAG.2005.846117
14. X. W. Wu, N. Q. Shu, L. Li, H. T. Li, H. Peng, "Finite element analysis of thermal problems in gasinsulated power apparatus with multiple species transport techniques," IEEE Trans. Magn., vol. 50, no. 2, pp. 321-324, Feb. 2014. https://doi.org/10.1109/TMAG.2013.2281989
15. B. Li, D. M. Xiao, S. Zhao, H. Zhang, "Temperature rise numerical calculation of the second generation gas insulated transmission line," Transaction of China Electrotechnical Society, vol. 32, no. 13, pp. 272-276, Jul. 2017. (in Chinese)
16. W. D. Bennon and F. P. Incropera, "A continuum model for momentum, heat and species transport in binary solid-liquid phase change systems-I. Model formulation," Int. J. Heat Mass Trans., vol. 30, no. 10, pp. 2161-2170, Oct. 1987. https://doi.org/10.1016/0017-9310(87)90094-9
17. J. D. Anderson, Computational Fluid Dynamics: The Basics with Applications, New York: Mc Graw-Hill, 1995, pp. 452-455.
18. Z. N. Zhao. Heat transfer theory. Beijing: Higher Education Press, 2008, pp. 177-179. (in Chinese)
19. L. J. Wu. Theoretical basis and design of large current bus-bars, Beijing: Water Conservancy and Hydropower Press, 1985, pp. 246-253, 1985 (in Chinese).
20. H. E. Nechmi, A. Beroual, A. Girodet, P. Vinson, "Fluoronitriles/$CO_2$ gas mixture as promising substitute to $SF_6$ for insulation in high voltage applications," IEEE. Trans. Dieletr. Electr. Insul., vol. 25, no. 5, pp. 2587-2593, Oct. 2016.
21. 3M USA SDS, $3M^{TM}$ $Novec^{TM}$ 4710 Dielectric Fluid, 33-6330-6, Version 2.03, 2015-02-04.
22. Common technical requirements for high-voltage switchgear and control equipment standards, GB/T 11022-2011, 2011-12-30 (in Chinese).
23. T. Magier, M. Tenzer, H. Koch. "Direct current gasinsulated transmission lines," IEEE Trans. Power Del., vol 33, no. 1, pp. 440-446, Feb. 2018.