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Tillförlitlighet i Stockholms elnät: En analys med hjälp av Tekla NIS
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
2015 (Swedish)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

Outages in the electric grid can be costly for society. Because of this, reliability is one of the parameters used to regulate network companies. Reliability in electrical grids can be measured with SAIDI, system average interruption duration index, which for Fortum Distribution has increased in Stockholm’s distribution network (11 kV) in the early 2000’s.

By using outage data for Stockholm from 2011-2013, sets of parameters to be used for reliability calculations in the network information program Tekla NIS were derived. Two different options for investment were then analysed: changing old cables with high fault frequencies, and installing automatic switching in distribution substations. These options were also analysed in a simplified model built in Microsoft Excel. The model calculates the reliability of Stockholm’s distribution network using Markov chains and the network’s average line from a transmission substation’s feeder.

The Excel model is faster than Tekla NIS but is limited and less detailed, however the results from Tekla NIS and the Excel model were found to be almost equivalent. The priority for reliability investments in Stockholm should be to change old cables of the type FCJJ since it increases the fault frequencies in the network, while an ageing network decreases the grid fees Fortum Distribution can charge.

Simplifications and assumptions, due to insufficient outage data and some problems with Tekla NIS, had to be made when deriving parameters for reliability calculations in both Tekla NIS and the Excel model. However, Tekla NIS can be used to incorporate reliability analysis in network planning, but since Fortum Distribution currently only uses it sparsely, further testing and analysis of the programme is recommended if the usage is to increase. The Excel model can be used for making fast and rough estimates of the result of the two analysed options of investment. 

Place, publisher, year, edition, pages
2015. , 71 p.
UPTEC ES, ISSN 1650-8300 ; 15034
Keyword [en]
CAIDI, electrical distribution systems, reliability analysis, SAIDI, SAIFI, Tekla NIS
Keyword [sv]
CAIDI, elektriska distributionssystem, SAIDI, SAIFI, Tekla NIS, tillförlitlighet, tillförlitlitghetsanalys
National Category
Energy Systems
URN: urn:nbn:se:uu:diva-257064OAI: oai:DiVA.org:uu-257064DiVA: diva2:827925
External cooperation
Fortum Distribution AB
Educational program
Master Programme in Energy Systems Engineering

I den tillgängliga fulltexten är tre figurer med tillhörande information i kapitel 2.4 borttagna från originalrapporten efter önskemål från samarbetspartner.

Available from: 2015-06-29 Created: 2015-06-29 Last updated: 2015-09-04Bibliographically approved

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