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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

Utvärdering av konsekvenserna för nätanslutning av vindkraftparker i Sverige vid införandet av nätkoden Requirements for Generators / Grid code compliance of wind farms in Sweden with the introduction of the NC-RfG

Andersson, Erik, Wengberg, Fredrik January 2015 (has links)
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. For manyof the requirements in the Requirements for Generators there is no equivalent in theSwedish Grid Code (SvK FS2005:2) but counterparts can thus be found in existingpractices and therefor does not imply any major differences for the industry. The requirements of frequency regulation, synthetic inertia and reactive powercapability are the main components of the RfG which will require additional softwareand hardware installations for future wind farms in Sweden.
2

Compliance with the EU Regulation Requirements for Generators in the Swedish Electricity Sector : A Study of how Compliance with the New Requirements can be Facilitated

Hedström, Andreas January 2020 (has links)
The EU regulation Requirements for Generators (RfG) was fully in force in Sweden in April 2019. With RfG, which contains requirements on the grid connection of new power-generating modules (PGMs), the EU aims to ensure a further market integration within the union, increase the security of supply and facilitate a continuous integration of renewable energy production. With the purpose of ensuring that the capabilities required in RfG are installed in new PGMs, compliance with the requirements must be shown before commissioning a new PGM via either on- site tests, simulations or both. However, the information RfG provided regarding how compliance is to be shown is vague. This has introduced ambiguity to the Swedish electricity sector with regards to what is required to show compliance. Therefore, in this study, an investigation of the Swedish compliance landscape with regards to RfG has been performed, with the objectives of shining light on obstacles that relevant actors in the industry experience and examining which incentives they have to comply with RfG today. Furthermore, the study gives a contribution to how compliance can be shown via templates of simulations for the requirements on wind power parks with a cumulative installed power of 10 MW to have the capability of delivering frequency regulation. The results indicate that the industry needs procedures of best practice and further guidelines or rules with regards to how compliance is to be shown to be able to achieve cost-effectiveness. Moreover, the templates provided in the study illustrate what types of guidelines that are demanded.
3

The Composition and Morphology of Coal Ash Deposits Collected in an Oxy-Fuel, Pulverized Coal Reactor

Stimpson, Curtis K. 31 May 2012 (has links) (PDF)
Coal ash deposits were collected in a 160 kWth, down-fired oxy-coal reactor under staged and unstaged conditions for four different coals (PRB, Gatling, Illinois #6, and Mahoning). Concentration measurements of carbon, oxygen, sodium, magnesium, aluminum, silicon, phosphorus, sulfur, chlorine, potassium, calcium, titanium, chromium, manganese, iron, nickel, strontium, and barium were gathered from each deposit sample using scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS). Backscattered electron micrographs for each deposit sample were analyzed to gather morphological data. Particle size and shape were studied for each deposit collected. The average particle sizes of the particles in upstream deposits were much larger than the average particle sizes of the downstream deposits. The downstream deposits consisted primarily of spherical particles while the upstream deposits consisted of round, irregular polygonal, and porous particles. Deposit particles are believed to have deposited at all stages of burnout; those depositing early during pyrolysis may have continued to react after deposition. Element maps for the aforementioned elements were collected with SEM-EDS and analyzed to quantify both average composition and composition of individual particles. These values were compared to ASTM ash analyses performed for each coal and ash collected from the flue gas stream with a cyclonic particle separator. It was found that sulfur concentrations of deposits do not correlate with corresponding sulfur concentrations of the coal. Comparison of similar experiments performed with air-combustion show that oxy-combustion deposits contain about twice as much sulfur as air-combustion deposits when burning the same coal. Deposition propensity of each coal was also examined, and the PRB and Gatling coals were found to have a moderately high deposition propensity whereas the deposition propensity of the Mahoning and Illinois #6 coals was fairly low.
4

Mechanical Properties of Icosahedral Viral Shells. A Molecular Dynamics Study / Die mechanischen Eigenschaften ikosaedrischer Virushüllen. Eine Molekulardynamik Studie

Zink, Mareike 16 March 2009 (has links)
No description available.
5

Reactive power compensation of the electricity grid with large-scale offshore wind farms in Sweden : Technical capabilities, grid codes and economic incentives

Bråve, Agnes, Särnblad, Sara January 2022 (has links)
Year 2040 the goal is to have a 100 % renewable Swedish energy system. Svenska kraftnät (Svk) predicts fully decommissioned nuclear power plants and an increased amount of connected wind power plants, especially offshore, year 2045. These kind of renewable power plants are non-synchronous and do not provide the grid with the same system stability services naturally as synchronous generators, such as nuclear power plants. With the increased number of renewables connected, one future challenge is to maintain the stability of the power grid. Grid stability can be divided into voltage-, frequency- and rotor angle stability.This thesis has investigated how large-scale offshore wind power plants (OWPPs) can contribute with reactive power compensation and in turn voltage stability to a nearby onshore power grid in Sweden. The evaluation has been done from the perspective of the TSO and the OWPP owner interests, with a focus on grid codes, economic incentives and technical capabilities.This project has been made in three parts. First, a comparison of voltage stability control requirements in different European grid codes was made. Secondly, static power flow simulations of a case study of a 1000 MW OWPP have been performed in PowerWorld Simulator, testing the OWPP’s reactive power outputs under different circumstances. Thirdly, a market opportunity analysis has been completed, analyzing reactive power market opportunities for OWPPs as well as for TSOs.The study shows that the reactive power capabilities of the simulated OWPP is considerable higher than the Swedish grid codes requires. Thus, an opportunity is to make the grid codes stricter, in combination with economic incentives. The case study showed that the distance offshore has an impact of the reactive power reaching the grid onshore. Though, the OWPP’s contribution to local voltage stability onshore is considered as good. Finally, with short- and long-term contracts, a reactive power market can be favorable for both the OWPP owner and the TSO.
6

Der elastisch aufgehängte starre Körper / The elastic suspended rigid body

Dathe, Henning 02 May 2001 (has links)
No description available.
7

Dynamické modely výrobních modulů / Dynamic Models of Power-Generating Modules

Kopička, Marek January 2021 (has links)
The dissertation thesis deals with the design of the concept and implementation of models of electrical power system elements with regard to the potential of the use of computer programs – simulations. The solution of the thesis focuses on the compliance simulations of power-generating modules according to RfG (Requirements for Generators), as a document which setting out the requirements for the connection of power-generating facilities and also focuses on the issue of smart grids and MAS (Multi-Agent Systems) respectively. The framework of the thesis is thus defined by the area of requirements for power-generating modules according to legislative requirements (not only RfG, but also related standards incl. DSC (Distribution System Code), CSN EN 50438 and CSN EN 50549), requirements for agent functionalities and power-generating module abilities to operate in synchronous and island operation, including transitions between them, the process of synchronization (phasing) and communication between the individual elements of the power system.
8

Untersuchungen zur Polymerdynamik an laserdeponierten Poly(alkyl methacrylat)-Filmen / Studies of the polymer dynamics in laser deposited poly(alkyl methacrylate)-films

Meschede, Andreas 27 January 2010 (has links)
No description available.
9

Random Block Copolymer Melts in the Bulk and at Selective Substrates / Zufallsblockkopolymerschmelzen im Volumen und an selektiven Substraten

Steinmüller, Birger 12 December 2011 (has links)
No description available.

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