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942 Uppsatser om Grid technique - Sida 1 av 63

Vad är god fysikundervisning? : Studie av några lärarstudenters uppfattning med Repertory Grid Technique

I studien har en relativt ovanlig intervjumetod, Repertory Grid Technology använts för att ge några blivande fysiklärares syn på god fysikundervisning. Metoden inspirerar till användning i många andra sammanhang. Resultaten visar att god fysikundervisning bland annat uppfattas som krävande för läraren..

User Experience utvärderingar med stöd av Repertory Grid Technique

Studiens syfte var att undersöka möjligheterna att använda intervjutekniken Repertory Grid technique (RGT) som utvärderingsteknik för att utvärdera User Experience (UX) på distans. Detta gjordes genom att de föreställningar som en handledarstödd utvärdering resulterade i jämfördes med det resultat som uppnåddes genom en webbaserad variant av samma utvärdering. Studiens resultat visade på en svårighet för respondenterna i den webbaserade utvärderingen att formulera föreställningar som går att använda för analys av en produkts UX. Diskussionen pekar på en tänkbar lösning i form av förstudier som utförs med en mindre grupp av respondenter för att på detta sätt hjälpa utvärderarna att skapa sig en referensram att använda vid tolkningen av de föreställningar som sedan kan samlas in under en webbaserad utvärdering. Studien syftade även till att jämföra vilka aspekter kopplade till UX som utvärderingarna genererade, samtliga av dessa kopplades till subjektiva eller produktrelaterade aspekter..

Nätnyttomodellen och dess inverkan på ett distributionsnät - En studie i samarbete med Härryda Energi AB

This report is intended to give an insight in the Network Performance Assessment Modeland the parameters that is needed in the making of a fictitious grid that represents anoptimal grid. A main goal is to investigate how the construction of a real grid iscompared to the fictitious.One of the key parameters is how redundancy is treated in the model and to find theoptimal amount of redundancy versus the costs. Further is the dimensioning of the grid ofinterest. The fictitious grid is based on energy whereas the real grid often is based onsubscribed power and these two principles are compared and analyzed.The difference in the outcome of the model result due to variations in input data of themodel is also discussed in the report..

Utveckling och tillämpning av modeller förkvantifiering av de ekonomiska konsekvensernaav ökad förbrukningsflexibilitet inom eldistribution

One step towards a more sustainable energy system is to create a more flexible electrical grid, where increased demand response among electricity consumers can play an important role. A distribution grid owner can encourage their customers to use electricity more evenly distributed during the day by introducing different types of grid fees such as time-differentiated power tariffs. In this master thesis, the theoretical economic impact of a flattened load profile for a distribution grid owner is investigated. Different factors that impact the distribution grid owner?s economy are identified and two are chosen to be quantified; losses in the grid and the fee to the feeding grid.

DIGITAL VISUALISERINGSTEKNIK : möjligheter, för- och nackdelar

Ever since the development of the pc and their software, in the early 80´s,architects way of work have changed a lot. Nowadays most of the architectspresent all their works digitally and not with hand drawn material, as they didbefore the pc boom.Digital visualisation technique pushes the limits, when it is about presentingarchitecture projects virtual reality.This report studies how digital visualization technique is used among thearchitects today.Together with architects from ABAKO architect firm in Gothenburg, Sweden,interviews has been made to give answers about what they think about digitalvisualization technique. What are the opportunities, advantages- anddisadvantage with this digital technique?The answers from the architects, together with work that has been done withdigital visualization technique in a project called Project Sofiedal, shows thatthis technique has big opportunities when it comes to create nice looking VRpresentations. The result in this report also shows that this digital technique ismore time demanding compared to hand drawn presentations.The investigation shows that digital visualization technique is a goodcompliment when it is about showing the citizens how future projects willaffect the surrounding.

Scandinavium : Sveriges största inomhusarena

Ever since the development of the pc and their software, in the early 80´s,architects way of work have changed a lot. Nowadays most of the architectspresent all their works digitally and not with hand drawn material, as they didbefore the pc boom.Digital visualisation technique pushes the limits, when it is about presentingarchitecture projects virtual reality.This report studies how digital visualization technique is used among thearchitects today.Together with architects from ABAKO architect firm in Gothenburg, Sweden,interviews has been made to give answers about what they think about digitalvisualization technique. What are the opportunities, advantages- anddisadvantage with this digital technique?The answers from the architects, together with work that has been done withdigital visualization technique in a project called Project Sofiedal, shows thatthis technique has big opportunities when it comes to create nice looking VRpresentations. The result in this report also shows that this digital technique ismore time demanding compared to hand drawn presentations.The investigation shows that digital visualization technique is a goodcompliment when it is about showing the citizens how future projects willaffect the surrounding.

Smarta elnät i Sverige : Energibranschens förutsättningar och förväntningar

The need for a more efficient electrical grid has made the smart grid concept popular in recent years. The aims of this study are to identify the conditions in Sweden for implementing a smart grid and to analyse the opinions of stakeholders. One finding is that the large capacity of Sweden?s existing electrical grid decreases the immediate need for smart grid solutions. However, the rapid increase in wind power might push the development of a smart grid in the coming years.

Framtidens elbilar utmanar nutidens elnät : Påverkan av ett ökat antal elbilar på ett halländskt elnät

The challenges facing low voltage grids are rising as an increasing number of domestic houses transition from fossil fueled heating to electricity based heating. Several environmental goals and visions have the same transition from fossil based power to electricity based power in mind for the transportation sector. One of the most important tools for this transformation is widely regarded to be the electric vehicle. With the demands of the electric vehicle pressuring the power grid, several questions arise regarding the growth of the electric vehicle market and what repercussions it may have on the grid. This paper focuses on a typical low voltage grid in southern Sweden and what effects a growing electric vehicle market may have on it. Through computer-assisted simulations based on several future scenarios regarding the EV market, this paper finds that few modifications and reinforcements are needed on this particular grid within the next 10 to 15 years.

Möjligheter och hinder för aggregerad förbrukningsflexibilitet som en produkt på reglerkraftmarknaden

Electricity production from renewable energy resources such as wind energy and photovoltaics is variable. Integration of these intermittent resources into the electricity system leads to new challenges in how to manage imbalance between supply and demand on the grid.One way to meet these challenges is to develop so-called smart grid solutions. One idea, called demand response, is to adjust the amount or timing of energy consumption, e.g. by control of household appliances, to provide flexibility that could be used to balance the grid. In aggregate, when applied to many units across the system, large volumes of energy could be made available when needed and this grid flexibility can be used as a product on the electricity regulation market.Despite the potential benefits, the number of demand response bids is currently low.

Utvärdering av konsekvenserna för nätanslutning av vindkraftparker i Sverige vid införandet av nätkoden Requirements for Generators

Grid codes are becoming more demanding on power generating units due to the factthat the complexity of the power grid is increasing. The penetration of wind powerhas grown over the last years and it is clear that wind farms need to be addressedwith the same type of grid codes as conventional generation units. There is howeveran undeniable difference between the technology in conventional synchronousgeneration units, and the asynchronous generation units in wind farms.This thesis has reviewed the current grid code in Sweden and compared it to the newcode proposed by ENTSO-E, ?the Requirements for Generators?, in the aspect ofwind farms with an installed power of 30 MW or more. The comparison has beencomplemented by an analysis of how wind farms of two different technologies(Doubly fed induction generators and full power converters) can meet therequirements and technical proposals have been given on how to be able to meetcompliance with the new grid codes.The Requirements for Generators contains many non-exhaustive and optionalrequirements, because of this it has been difficult to, at this stage, exactly point outthe technical impact on the grid connection of future wind farms in Sweden.

Matematisk kod i grafisk design

Målet har varit att undersöka hur grafiska formgivare kan använda sig av matematisk kod i form av fraktala system för att skapa inspirerande grid. Genom att titta på befintliga fraktala mönster och sedan anpassa vissa av dem till gridsystem skapades under designprocessen ett antal olika fraktala grid. Hur väl dessa gridsystem fungerade testades i en skisskalender - en fickkalender för formgivare med plats att skissa. För att kontrollera och verifiera de resultat som kom fram under designprocesssen jämfördes de med åsikter från en fokusgrupp bestående av grafiska formgivare. Slutsatsen blev att fraktala gridsystem inspirerar grafiska formgivare att skapa dynamiska och harmoniska layouter.

Numerisk modell för global transport av spårämnen i atmosfären

The aim of this project was to develop a numerical model simulating the global transport of air pollution. The model currently used by SMHI, the Swedish Meteorological and Hydrological Institute, was intended to perform such simulations at regional scales. However, the usage of a grid based on longitudes and latitudes makes this model work poorly in global simulations. The problem with this grid is that the nodes are concentrated near the North and South Poles. Due to this characteristic, the Courant, Friedrich and Lewy-condition for numerical stability puts a sharp bound on the timestep length.

Trafikverkets effektstyrningssystem - EFS 132 kV : Bidraget till minskade förluster

The technological legacy from the early electrification of the Swedish railroads has resulted in a power grid with a lower grid frequency than the national power grid from which it is fed. Energy transfer between these power grids with different frequencies requires substations, adapting the grid frequency for the rail road power grid. For this purpose, a feeding power grid has been built, stretching across the country from Boden in the north to Tälle/Häggvik in the south.Power transfer in the Swedish power grid results in voltage angle differences which increase with increasing loads and transfer distance. These voltage angle differences are transferred from the power feeding substations to the rail road power grid, will in some extent cause loss of energy due to unwanted power flows from north to south.To minimize the losses due to this phenomenon, a power management system called EFS 132 kV has been developed and implemented. The system minimizes the unwanted power flows and controls the desired power flow for a good distribution of loads between the power feeding substations.This thesis investigates the extent of the transmission losses avoided due to the EFS 132 kV that coordinates the idling angles to a common reference point.The results indicate that EFS 132 kV affects the power flow, especially between the northern substations through an improved load distribution.

Risk- och sårbarhetsanalyser för smarta elnät

The electrical grid needs to be changed in the future in order to manage more distributed and renewable generation and also to make it possible for electricity consumers to be more active and aware of their electricity consumption. This future grid is usually referred to as a smart grid. With the transition to a smart grid, new challenges occur. One method to determine those challenges is to perform risk and vulnerability analyses. InStockholm, the new urban district Stockholm Royal Seaport is built.

Undersökning av elkvalitet i distributionsnät med omfattande vindkraftselproduktion

The goal for this master thesis project has been to investigate the power quality in adistribution grid, which has a high fraction of dispersed power production due towindmills. The study has been done on a grid in Laholm South of Halmstad, whereapproximately 45 windmills are connected to the distribution grid owned by SHKEnergi. The investigation has been focused on to two radialy fed 20 kV lines, wheretwelve windmills are connected.Voltage variations have been studied by creating a model of the grid in the simulationprogram SIMPOW. The largest deviation that has been found in any point of the gridis ±1.9 % of the nominal voltage. This deviation is a result of varying powergeneration from the windmills and the voltage regulation at the connection point ofthe line.

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