Investigation of Lightning-Initiated Flashover Faults in Medium Voltage Overhead Lines - Modelling and Experimental Evaluation

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dc.contributorAalto-yliopistofi
dc.contributorAalto Universityen
dc.contributor.advisorLehtonen, Matti, Prof., Aalto University, Department of Electrical Engineering and Automation, Finland
dc.contributor.authorMahmood, Farhan
dc.contributor.departmentSähkötekniikan ja automaation laitosfi
dc.contributor.departmentDepartment of Electrical Engineering and Automationen
dc.contributor.labPower Systems and High Voltage Engineeringen
dc.contributor.schoolSähkötekniikan korkeakoulufi
dc.contributor.schoolSchool of Electrical Engineeringen
dc.contributor.supervisorLehtonen, Matti, Prof., Aalto University, Department of Electrical Engineering and Automation, Finland
dc.date.accessioned2016-05-17T09:01:09Z
dc.date.available2016-05-17T09:01:09Z
dc.date.defence2016-05-23
dc.date.issued2016
dc.description.abstractLightning can cause flashovers on Medium Voltage (MV) lines from both direct and nearby strikes. The work presented in this dissertation thoroughly investigates the characteristics of lightning-initiated flashover faults, expected overvoltage stress and the performance of different surge protection schemes to mitigate the lightning overvoltages. A full-scale experimental set-up is established to investigate the nature of lightning-initiated flashover faults in MV lines. The flashover voltage of the overhead line is determined by changing the type (metallic/wood) and the configuration (grounded/ungrounded) of the cross arm. On the other hand, the instant at which the flashover occurs is determined by the actual volt-time curve of the line insulation whereas the arcing phenomenon is represented by the dynamic arc model. A complete model of the experimental set-up is developed in Alternative Transients Program–Electromagnetic Transients Program (ATP-EMTP) and the experimental results have been reproduced with reasonable accuracy. The lightning performance of a typical MV unearthed network due to both first and subsequent direct strokes is also analyzed. The transient overvoltages at the MV terminals of distribution transformer are determined from ATP-EMTP simulations. Accordingly, the effectiveness of different lightning protection schemes based on of spark gaps and surge arresters is also assessed. The volt-time curves and the flashover probability distributions of different types of insulation gaps subjected to positive and negative standard and short tail impulse voltages were established. The study was further extended by testing the insulation gaps with combined AC and lightning impulse voltages. The experimental flashover probability distributions are then compared with those predicted by the modified Gaussian cumulative distribution function of the insulation flashover under combined voltages. A statistical method of insulation coordination based on probabilistic risk assessment is also introduced in this work to evaluate the lightning performance of MV lines. In this regard, the probabilistic model of insulation flashover is experimentally validated to predict the probability of single-phase, two-phase, and three-phase flashover of insulators. Accordingly, the effect of combined AC and lightning-induced overvoltages on the risk of flashovers above perfectly conducting and lossy ground is also investigated. Finally, the risk-based insulation coordination method is applied to determine the optimum insulation level and spacing between the consecutive surge arresters for the mitigation of lightning-induced overvoltages.en
dc.format.extent117 + app. 103
dc.format.mimetypeapplication/pdfen
dc.identifier.isbn978-952-60-6764-3 (electronic)
dc.identifier.isbn978-952-60-6763-6 (printed)
dc.identifier.issn1799-4942 (electronic)
dc.identifier.issn1799-4934 (printed)
dc.identifier.issn1799-4934 (ISSN-L)
dc.identifier.urihttps://aaltodoc.aalto.fi/handle/123456789/20367
dc.identifier.urnURN:ISBN:978-952-60-6764-3
dc.language.isoenen
dc.opnKizilcay, Mustafa, Prof., University of Siegen, Germany
dc.opnAmetani, Akihiro, Prof., Doshisha University, Japan
dc.publisherAalto Universityen
dc.publisherAalto-yliopistofi
dc.relation.haspart[Publication 1]: F. Mahmood and M. Lehtonen “Experimental Investigation of Lightning-Initiated Flashover Faults in Medium Voltage Lines,” International Conference on High Voltage Engineering and Applications (ICHVE’14), Poznan, Poland, Sept. 8-11, 2014
dc.relation.haspart[Publication 2]: F. Mahmood, N. I. Elkalashy and M. Lehtonen “Modelling of Flashover Arcs in Medium Voltage Networks Due to Direct Lightning Strikes,” International Journal of Electrical Power and Energy Systems (JEPE), vol. 65, 2015, pp. 59-69. DOI: 10.1016/j.ijepes.2014.09.036
dc.relation.haspart[Publication 3]: F. Mahmood, M. E. M. Rizk and M. Lehtonen “Evaluation of Lightning Overvoltage Protection Schemes for Pole-Mounted Distribution Transformers,” International Review of Electrical Engineering (IREE), vol. 10, no. 5, Sep./Oct. 2015, pp. 616-624. DOI: 10.15866/iree.v10i5.7266
dc.relation.haspart[Publication 4]: F. Mahmood, M. E. M. Rizk, N. A. Sabiha and M. Lehtonen “Flashover Probability Distribution and Volt-time Curves of Medium Voltage Overhead line Insulation under Combined AC and Lightning Impulse Voltages,” International Review of Electrical Engineering (IREE), vol. 10, no. 5, Sep./Oct. 2015, pp. 625-632. DOI: 10.15866/iree.v10i5.7150
dc.relation.haspart[Publication 5]: F. Mahmood, N. A. Sabiha and M. Lehtonen “Probabilistic Risk Assessment of MV Insulator Flashover under Combined AC and Lightning-Induced Overvoltages,” IEEE Transactions on Power Delivery, vol. 30, no. 4, Aug. 2015, pp. 1880-1888. DOI: 10.1109/TPWRD.2015.2388634
dc.relation.haspart[Publication 6]: F. Mahmood, N. A. Sabiha and M. Lehtonen “Effect of Combined AC and Lightning-Induced Overvoltages on the Risk of MV Insulator Flashovers above Lossy Ground” Electric Power Systems Research, vol. 127, 2015, pp. 101-108. DOI: 10.1016/j.epsr.2015.05.016
dc.relation.haspart[Publication 7]: F. Mahmood, M. Humayun and M. Lehtonen “Risk-Based Design Methodology for the Selection of Insulation Level Against Lightning-Induced Overvoltages in Medium Voltage Lines,” 19th International symposium on High Voltage Engineering (ISH’15), Pilsen, Czech Republic, Aug. 23-28, 2015
dc.relation.haspart[Publication 8]: F. Mahmood, M. E. M. Rizk, N. I. Elkalashy and M. Lehtonen “Application of Risk-Based Insulation Coordination Method for the Protection of Medium Voltage Overhead Lines against AC and Lightning-Induced Superimposed Voltages,” submitted to Electric Power Systems Research, 2016
dc.relation.ispartofseriesAalto University publication series DOCTORAL DISSERTATIONSen
dc.relation.ispartofseries70/2016
dc.revAmetani, Akihiro, Prof., Doshisha University, Japan
dc.revTaklaja, Paul. Dr., Tallinn University of Technology, Estonia
dc.subject.keywordlightningen
dc.subject.keywordinsulator flashoveren
dc.subject.keywordmedium voltage lineen
dc.subject.keywordarcen
dc.subject.keywordrisken
dc.subject.keywordtransformeren
dc.subject.keywordsurge arresteren
dc.subject.keywordshield wireen
dc.subject.keywordspark gapen
dc.subject.keywordATP-EMTP.en
dc.subject.otherElectrical engineeringen
dc.titleInvestigation of Lightning-Initiated Flashover Faults in Medium Voltage Overhead Lines - Modelling and Experimental Evaluationen
dc.typeG5 Artikkeliväitöskirjafi
dc.type.dcmitypetexten
dc.type.ontasotDoctoral dissertation (article-based)en
dc.type.ontasotVäitöskirja (artikkeli)fi
local.aalto.archiveyes
local.aalto.formfolder2016_05_16_klo_12_24
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