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A new static calculation of the streamer region for long spark gaps
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity. (Lightning research group)
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity. (Lightning research group)
ABB AB, Power systems HVDC, Ludvika.
ABB AB, Power Systems HVDC, Ludvika.
2012 (English)In: Journal of Electrostatics, ISSN 0304-3886, Vol. 70, no 1, 15-19 p.Article in journal (Refereed) Published
Abstract [en]

Different electrostatic approximations have been proposed to calculate the streamer region without going in deep details of the behavior of density of particles under the effect of high electric fields; this kind of approximations have been used in numerical calculations of long spark gaps and lightning attachment. The simplifications of the streamer region are achieved by considering it to be a geometrical region with a constant geometrical shape. Different geometrical shapes have been used, such as cones or several parallel filaments. Afterward, to simplify the procedures, the streamer region was approximated by two constants, one denoted K-Q, called the geometrical constant and in other cases K named as geometrical factor. However, when a voltage that varies with time is applied to an arrangement of electrodes (high voltage and grounded electrodes), the background electric field will change with time. Thus, if the background electric field is modified, the streamer zone could cover a larger or smaller area. With the aim of reducing the number of assumptions required in the calculation of long gap discharges, a new electrostatic model to calculate the streamer region is presented. This model considers a variable streamer zone that changes with the electric field variations. The three-dimensional region that fulfills the minimum electric field to sustain a streamer is identified for each time step, and the charge accumulated in that region is then calculated. The only parameter that is being used in the calculation is the minimum electric field necessary for the propagation of streamers.

Place, publisher, year, edition, pages
2012. Vol. 70, no 1, 15-19 p.
Keyword [en]
charge, leader, Streamer, Electrical charge, Electric field, Corona inception, Discharge
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electricity, Esp The Study Of Transients and Discharges; Engineering Science with specialization in Science of Electricity
URN: urn:nbn:se:uu:diva-150528DOI: 10.1016/j.elstat.2011.07.013ISI: 000300804300003OAI: oai:DiVA.org:uu-150528DiVA: diva2:407586
Available from: 2011-03-31 Created: 2011-03-31 Last updated: 2012-09-20Bibliographically 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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