Numerical Evaluation on the Propagation of Non-breakdown Streamer in Natural Ester under Negative Lightning Impulse Voltage via Shadowgraph Imaging

A modified shadowgraph imaging setup equipped with a high-speed camera is utilized to achieve a numerical evaluation of temperature, number densities of molecules, ions and electrons to the refractive-index of negative non-breakdown streamer in rapeseed insulating oil for revealing the dynamics of s...

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Bibliographic Details
Published in:	IEEE transactions on dielectrics and electrical insulation 2021-08, Vol.28 (4), p.1198-1206
Main Authors:	Li, Xiangrong, Wang, Feipeng, Wang, Kaizheng, Huang, Zhengyong, Wang, Qiang, Li, Chen, Long, Yunfeng, Pan, Jianyu, Li, Jian
Format:	Article
Language:	eng
Subjects:	Breakdown Electrons Gray-scale High speed cameras Ionization natural ester insulating oil negative non-breakdown streamer Nonhomogeneous media Oils Positive ions Propagation Rapeseed Refractive index Refractivity shadowgraph imaging Streaming media Temperature distribution Triglycerides
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Summary:	A modified shadowgraph imaging setup equipped with a high-speed camera is utilized to achieve a numerical evaluation of temperature, number densities of molecules, ions and electrons to the refractive-index of negative non-breakdown streamer in rapeseed insulating oil for revealing the dynamics of streamer propagation. The non-breakdown streamer is found reaching fairly high speed of 3.01-4.66 km/s during 0{-}1.7 \ \mu\mathrm{s} . The following 10 µs is dominated by streamer propagation with the grayscale decreasing continuously for the entire streamer. The dissipation is identified starting at ca. 11.7 \ \mu\mathrm{s} in the stem region while the head of streamer remaining further propagation. This is followed by a dissipation expansion from the stem to the head regions. The double-unsaturated triglycerides are evidenced as the main ionization components in the non-breakdown streamer, which aid to identify the temperature variations, instead of electrons, positive ions, or dissociation of molecules, contribute mainly to the refractive index drop of the streamer. The mapping for the temperature distribution of streamer is resultantly possible and provides the insight to ascertain the inhomogeneous migration of electrons the kinetic superiority for the streamer evolution dynamics.
ISSN:	1070-9878 1558-4135