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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Studie över klimatförändringars påverkan på dynamisk ledningskapacitet / Study of the impact of climate change on dynamic line rating

Hahne, Linnea January 2021 (has links)
The thesis aims to examine the impact of climate change on line rating and to investigate the possibility of a potential increase of capacity of an overhead line. The line rating of an overhead line determines how much current can be transmitted in the line. The weather parameters which affect the line rating are ambient temperature, solar radiation, wind speed, and wind direction. If the line rating is adapted to weather conditions, it is important to be able to predict how the weather will change in the future. Therefore, the impact of climate change on weather parameters is investigated. The ambient temperature and solar radiation are expected to change between different scenarios. However, it is unclear how wind speed and wind direction will be affected. Climate scenarios are designed that take these findings into account. The results show that wind speed has, by a large margin from other weather parameters, the largest impact on the dynamic line rating. This is followed by the wind's angle of attack to the conductor, ambient temperature, and finally solar radiation. For the designed climate scenarios, the dynamic line rating is almost the same in each case, which means that the calculated change in ambient temperature and solar radiation has no significant effect on the line rating. To further increase the capacity of the overhead line, the line could be upgraded with a conductor with a larger cross-sectional area.
2

Jämförande analys av åtgärder vid kapacitetsbrist i kraftledningar / Comparative analysis of measures in the event of capacity shortages in transmission lines

Dahlstrand, Daniel January 2022 (has links)
Marknadsanalyser gjorda av Svenska kraftnät visar att elenergianvändningen i Sverige kommer att öka. Denna utveckling drivs på av bland annat omställningen till elektriska transporter och kan potentiellt leda till kapacitetsbrist i ledningar inom transmissions- och regionnät, framför allt i storstadsområden. För att kunna reducera kapacitetsbrist i en ledning finns det ett antal åtgärder, men hur dessa står sig mot varandra i ett tekniskt och ekonomiskt perspektiv är inte fastställt. Det är där denna rapport tar vid. Bland annat studeras Dynamic line rating (DLR) som en åtgärd för att reducera kapacitetsbristen i den studerade ledningen. DLR är en teknik som används för att justera den maximalt tillåtna överföringskapaciteten i en ledning baserat på ett antal parametrar. Beräkningarna för att bestämma maximalt tillåtna överföringskapaciteten i ledningen gjordes på två olika sätt detta för att undersöka om de var likvärdiga. Det visade sig att de stämde relativt bra överens, dock med en offset. Den potentiella överlasten skulle inträffa under 3379 timmar under ett år, men enbart om en specifik transformator gick sönder. Medeltiden till felet visade sig vara 173 år utan att några åtgärder applicerades. För att nå upp till 100 % tillgänglighet på ledningen, utan åtgärder, skulle det behöva köpas flexibilitetstjänster motsvarande 82150 MWh (Megawattimmar) under det studerade året.  Även den ekonomiska kostnaden för att köpa upp- eller nedreglerande tjänster studerades. Rapporten visar att det för den studerade ledningen var till fördel att investera i DLR vid ett flexibilitetsbehov på 1,2 GWh/år. Från resultatet utformades ett förslag på lämplig ordning för att nyttja de olika åtgärdena samt förslag på vidareutveckling av arbetet. Slutsatsen är att åtgärderna har sina för- och nackdelar, men att det inte går att säga att någon åtgärd är bättre än någon annan. Detta gäller inom samtliga områden som studerades. / Market analyzes made by Svenska kraftnät show that electricity use in Sweden will increase. This development is driven by, among other things, the transition to electric transport and can potentially lead to a lack of capacity in lines within backbone and regional networks, especially in metropolitan areas. In order to be able to reduce capacity shortages in a transmission line, there are a number of measures, but how these stand against each other in a technical and economic perspective has not been determined. That's what this report tries to answer.  Among other things, Dynamic line rating (DLR) is studied as a measure to reduce the capacity shortage in the studied transmission line. DLR is a technology used to adjust the maximum allowable transmission capacity in a line based on a number of parameters. The calculations to determine the maximum allowable transmission capacity in the transmission line were made in two different ways to examine whether they were equivalent. It turned out that they matched relatively well, though with an offset. The potential overload would occur during 3379 hours in a year, but only if a specific transformer broke down. The mean time to failure turned out to be 173 years without any measures being applied. In order to achieve up to 100 % availability on the line, without measures, it would be necessary to purchase flexibility services corresponding to 82150 MWh (Megawatt hours) during the year studied. The financial cost of buying up or down regulation services was also studied. The report shows that it was advantageous for the studied transmission line to invest in DLR at a flexibility requirement of 1.2 GWh / year. From the results, a proposal was made for an appropriate arrangement for using the various measures as well as proposals for further development of the work. The conclusion is that the measures have their advantages and disadvantages, but it is not possible to say that one measure is better than another. This applies to all areas studied.

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