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Numerical Simulations of Long Spark and Lightning Attachment
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity. (Lightning Research Group)
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.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 820
Keyword [en]
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
Identifiers
URN: urn:nbn:se:uu:diva-149171ISBN: 978-91-554-8060-8OAI: oai:DiVA.org:uu-149171DiVA: diva2:408623
Public defence
2011-05-25, Häggsalen, Ångström Laboratory, Lägerhyddsvägen 1, Uppsala, 10:00 (English)
Opponent
Supervisors
Available from: 2011-04-29 Created: 2011-03-15 Last updated: 2011-05-13Bibliographically approved
List of papers
1. Modelling of Positive Discharges in Laboratory Gaps under Switching impulses
Open this publication in new window or tab >>Modelling of Positive Discharges in Laboratory Gaps under Switching impulses
2008 (English)Conference paper (Refereed)
Place, publisher, year, edition, pages
Cardiff, UK: , 2008
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-113403 (URN)
Conference
XVII International Conference on Gas Discharges and Their applications
Available from: 2010-01-28 Created: 2010-01-28 Last updated: 2016-04-12Bibliographically approved
2. Breakdown effect on long gaps under switching impulses statistical variation
Open this publication in new window or tab >>Breakdown effect on long gaps under switching impulses statistical variation
2008 (English)Conference paper (Refereed)
Place, publisher, year, edition, pages
Uppsala, Sweden: , 2008
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-113402 (URN)
Conference
29th International Conference on Lightning Protection
Available from: 2010-01-28 Created: 2010-01-28 Last updated: 2016-04-12Bibliographically approved
3. Breakdown times and voltages probability calculation using a simplified numerical methodology
Open this publication in new window or tab >>Breakdown times and voltages probability calculation using a simplified numerical methodology
2008 (English)Conference paper (Refereed)
Place, publisher, year, edition, pages
Florianopolis Brazil: , 2008
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-113401 (URN)
Conference
International Conference on Grounding and Earthing and 3rd International Conference on Lightning Physics and Effects
Available from: 2010-01-28 Created: 2010-01-28 Last updated: 2016-04-12Bibliographically approved
4. Numerical simulation of long laboratory sparks generated by positive switching impulses
Open this publication in new window or tab >>Numerical simulation of long laboratory sparks generated by positive switching impulses
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.

Keyword
Discharge, Leader, Modeling, Switching
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-113133 (URN)10.1016/j.elstat.2008.12.022 (DOI)000266019500029 ()0304-3886 (ISBN)
Available from: 2010-01-25 Created: 2010-01-25 Last updated: 2016-04-14Bibliographically approved
5. LABORATORY LONG GAPS SIMULATION CONSIDERING A VARIABLE CORONA REGION
Open this publication in new window or tab >>LABORATORY LONG GAPS SIMULATION CONSIDERING A VARIABLE CORONA REGION
2010 (English)Conference paper (Refereed)
Place, publisher, year, edition, pages
Cagliary, Italy: , 2010
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Atmospheric Discharges
Identifiers
urn:nbn:se:uu:diva-140390 (URN)
Conference
30TH International Conference on Lightning Protection, ICLP
Available from: 2011-01-05 Created: 2011-01-05 Last updated: 2016-03-03
6. A RELIABLE NUMERICAL METHOD FOR THE CALCULATION OF BREAKDOWN VOLTAGES
Open this publication in new window or tab >>A RELIABLE NUMERICAL METHOD FOR THE CALCULATION OF BREAKDOWN VOLTAGES
2010 (English)Conference paper (Refereed)
Place, publisher, year, edition, pages
Cagliary, Italy: , 2010
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Atmospheric Discharges
Identifiers
urn:nbn:se:uu:diva-140391 (URN)
Conference
30TH International Conference on Lightning Protection, ICLP
Available from: 2011-01-05 Created: 2011-01-05 Last updated: 2014-12-10
7. A new static calculation of the streamer region for long spark gaps
Open this publication in new window or tab >>A new static calculation of the streamer region for long spark gaps
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.

Keyword
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
Identifiers
urn:nbn:se:uu:diva-150528 (URN)10.1016/j.elstat.2011.07.013 (DOI)000300804300003 ()
Available from: 2011-03-31 Created: 2011-03-31 Last updated: 2012-09-20Bibliographically approved
8. The development of long spark gaps: Simulation including a variable streamer region
Open this publication in new window or tab >>The development of long spark gaps: Simulation including a variable streamer region
(English)Article in journal (Refereed) Submitted
Keyword
Breakdown, streamer, discharge
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Science with specialization in Atmospheric Discharges
Identifiers
urn:nbn:se:uu:diva-150531 (URN)
Available from: 2011-03-31 Created: 2011-03-31 Last updated: 2016-03-03
9. Reliable model for the calculation of negative leader discharges under switching impulses
Open this publication in new window or tab >>Reliable model for the calculation of negative leader discharges under switching impulses
2010 (English)Conference paper (Refereed)
Keyword
negative streamer, space leader, breakdown
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Science with specialization in Atmospheric Discharges
Identifiers
urn:nbn:se:uu:diva-150533 (URN)
Conference
36th grounding and 4th Lightning Physics conference GND&LPE
Available from: 2011-03-31 Created: 2011-03-31 Last updated: 2016-04-18
10. A preliminary model to simulate negative leader discharges
Open this publication in new window or tab >>A preliminary model to simulate negative leader discharges
(English)In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463Article in journal (Refereed) Submitted
Keyword
Negative streamer, pilot system, breakdown
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Science with specialization in Atmospheric Discharges
Identifiers
urn:nbn:se:uu:diva-150532 (URN)
Available from: 2011-03-31 Created: 2011-03-31 Last updated: 2016-03-03
11. On the interception of lightning flashes by power transmission lines
Open this publication in new window or tab >>On the interception of lightning flashes by power transmission lines
2011 (English)In: Journal of Electrostatics, ISSN 0304-3886, E-ISSN 1873-5738, Vol. 69, no 3, 220-227 p.Article in journal (Refereed) Published
Abstract [en]

The design of the lightning protection system LPS of transmission lines is based on the well knownelectro-geometrical model. The electro-geometrical model assumes that the first point on a powertransmission line that will come within striking distance of the tip of a down-coming stepped leaderchannel is the strike point of the lightning flash. The model neglects almost all of the physics associatedwith the lightning attachment.Nowadays, as it is possible to use modern hardware and software tools and several different numericalmethods, it is feasible to apply the physics of the discharge process to the study of lightning attachment.Such models take into account the movement of the downward and the resulting upward leaders fromdifferent points on the structures under consideration.In this paper, a procedure based on lightning physics was used to analyze the lightning attachmentphenomena in EHV transmission lines of 230 kV and 500 kV and the results were compared with thepredictions of the electro-geometrical method.

Keyword
power system, lightning attachment, breakdown, downward leader
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Science with specialization in Atmospheric Discharges
Identifiers
urn:nbn:se:uu:diva-150534 (URN)10.1016/j.elstat.2011.03.013 (DOI)000292230300012 ()
Available from: 2011-03-31 Created: 2011-03-31 Last updated: 2016-04-19
12. 'The mesh method' in lightning protection standards - Revisited
Open this publication in new window or tab >>'The mesh method' in lightning protection standards - Revisited
2010 (English)In: Journal of Electrostatics, ISSN 0304-3886, E-ISSN 1873-5738, Vol. 68, no 4, 311-314 p.Article in journal (Refereed) Published
Abstract [en]

At present the design of the Lightning protection systems (LPS) for structures as stipulated in standards is based on the electro - geometrical method, which was initially used to protect power lines from lightning. A derivative of the electro-geometrical method is the rolling sphere method. This method together, with the protection angle method and mesh method are used almost in all lightning standards as the measure in installing the lightning protection systems of grounded structures. In the mesh method, the dimension of the cell size in different levels of protection is determined using the rolling sphere method. Since the rolling sphere method does not take into account the physics of the lightning attachment process there is a need to evaluate the validity of the stipulated value in standards of the minimum lightning current that can penetrate through the mesh in different levels of protection. In this paper, meshes of different sizes as stipulated in the lightning protection standards were tested for their ability to intercept lightning flashes using a lightning attachment model that takes into account the physics of connecting leaders on. The results are in reasonable agreement with the specifications given in the lightning protection standards.

Keyword
Dynamic leader, Electro-geometrical method, Lightning inception, Mesh method, Upward leader, Standards
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-135183 (URN)10.1016/j.elstat.2010.03.003 (DOI)000281211700004 ()
Available from: 2010-12-06 Created: 2010-12-06 Last updated: 2016-04-18Bibliographically approved
13. Influence of multiple upward connecting leaders initiated from the same structure on the lightning attachment process
Open this publication in new window or tab >>Influence of multiple upward connecting leaders initiated from the same structure on the lightning attachment process
2009 (English)Conference paper (Refereed)
Keyword
electric field, inhibit discharge, breakdown, streamer, lightning, attachment
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Science with specialization in Atmospheric Discharges
Identifiers
urn:nbn:se:uu:diva-150535 (URN)
Conference
X International symposium on lightning protection - SIPDA
Available from: 2011-03-31 Created: 2011-03-31 Last updated: 2016-04-14
14. Interaction of multiple connecting leaders issued from a grounded structure simulated using a self consistent leader inception and propagation model SLIM
Open this publication in new window or tab >>Interaction of multiple connecting leaders issued from a grounded structure simulated using a self consistent leader inception and propagation model SLIM
2010 (English)In: 30TH International Conference on Lightning Protection, ICLP, Cagliary, Italy, 2010Conference paper (Refereed)
Place, publisher, year, edition, pages
Cagliary, Italy: , 2010
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-142452 (URN)
Conference
30TH International Conference on Lightning Protection, ICLP
Available from: 2011-01-14 Created: 2011-01-14 Last updated: 2016-04-19Bibliographically approved

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