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Numerical simulation of long laboratory sparks generated by positive switching impulses
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
2009 (English)In: Journal of Electrostatics, ISSN 0304-3886, E-ISSN 1873-5738, Vol. 67, no 2-3, 228-234 p.Article in journal (Refereed) Published
Abstract [en]

A numerical methodology using two different leader channel criteria has been implemented. The methodology is based on Bondiou and Gallimberti's proposition [A. Bondiou, I. Gallimberti, Theoretical modelling of the development of the positive spark in long spark, J. Phys. D: Appl. Phys. 27 (1994) 1252-1266]. The leader channel criteria used are Rizk engineering criterion [Rizk, A model for switching impulse leader inception and breakdown of long air gaps, IEEE Trans. Power Deliv., 4(1) (1989)] and Local thermodynamic - L.T.E. - physical concept [I. Gallimberti, The mechanism of the long spark formation, Colloque C7, J. Phys. (supplement au nro 7, Tome 40) (July 1979) C7-193]. The methodology was tested in three different cases; a deterministic case, a statistical variation and a typical constant level test. Deterministic calculation considered corona inception using stabilization corona electric field criterion of Gallimberti [I. Gallimberti, The mechanism of the long spark formation, Colloque C7, J. Phys. (supplement au nro 7, Tome 40) (July 1979) C7-193] and the leader moving as segments. The statistical simulation has two different statistical delays, one at inception and the other due to the tortuous characteristics of the leader channel. The constant level test consists of 200 positive switching impulses with the same characteristics such as maximum applied voltage, time to crest and time to fall. Time to breakdown and breakdown voltage were found based on the results obtained from the constant level test characteristics. All the numerical results presented are based on experimental conditions reported in [Les Renardières Group, Research on long gap discharges at Les Renardières, Electra N 35 (1973)] from the world class research group namely Les Renardieres Group.

Place, publisher, year, edition, pages
2009. Vol. 67, no 2-3, 228-234 p.
Keyword [en]
Discharge, Leader, Modeling, Switching
National Category
Engineering and Technology
URN: urn:nbn:se:uu:diva-113133DOI: 10.1016/j.elstat.2008.12.022ISI: 000266019500029ISBN: 0304-3886OAI: oai:DiVA.org:uu-113133DiVA: diva2:289925
Available from: 2010-01-25 Created: 2010-01-25 Last updated: 2016-04-14Bibliographically approved
In thesis
1. Numerical Simulations of Long Spark and Lightning Attachment
Open this publication in new window or tab >>Numerical Simulations of Long Spark and Lightning Attachment
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The research work presented here is concerned with numerical simulations of two different electrical phenomena: Long gap electrical discharges under switching impulses and the lightning attachment process associated with positive upward leaders. The development of positive upward leaders and the progression of discharges in long gaps are attributable to two intertwined physical phenomena, namely, the leader channel and the streamer zone. The physical description and the proposed calculations of the above-mentioned phenomena are based on experimental tests conducted in long spark gaps.

The methodology presented here proposes a new geometrical approximation for the representation of the streamer and the calculation of the accumulated electrical charge. Furthermore, two different approaches to representing the leader channel are applied and compared. Statistical delays before the inception of the first corona, and random distributions to represent the tortuous nature of the path taken by the leader channel were included based on the behavior observed in experimental tests, with the intention of ensuring the discharge behaved in a realistic manner. A reasonable agreement was found between the physical model and the experimental test results.

A model is proposed to simulate the negative discharges produced by switching impulses using the methodology developed to simulate positive leader discharges and the physics underlying the negative leader phenomena. The validation of the method demonstrated that phenomena such as the pilot leader and negative leader currents are successfully represented.

In addition, based on previous work conducted on the physics of lightning and the lightning attachment process, a new methodology is developed and tested. In this new approach, the background electric field and the ionized region, considered in conjunction with the advance of the leader segment, are computed using a novel method. The proposed methodology was employed to test two engineering methods that are accepted in international standards, the mesh method and the electro-geometrical method. The results demonstrated that the engineering approximations are consistent with the physical approach.

In addition to the electrical phenomena mentioned above, one should remember that, to simplify the calculation, there are certain real effects arising from the lightning attachment process that have not been considered. In fact, when a structure is subjected to a strong electric field, it is possible to generate multiple upward leaders from that structure. This effect has not been taken into account in the numerical models available previously, and therefore the process of generating multiple upward leaders incepted over a structure is incorporated here. The results have shown that a slight advantage from the background electric field is enough for one upward connecting leader to take over, thereby forcing the others to abort the attachment process.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2011. 91 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 820
breakdown, discharge, leader channel, lightning attachment, negative discharge, positive discharge, streamer
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Science with specialization in Atmospheric Discharges
urn:nbn:se:uu:diva-149171 (URN)978-91-554-8060-8 (ISBN)
Public defence
2011-05-25, Häggsalen, Ångström Laboratory, Lägerhyddsvägen 1, Uppsala, 10:00 (English)
Available from: 2011-04-29 Created: 2011-03-15 Last updated: 2011-05-13Bibliographically approved

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