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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

Availability concepts and applications /

Reistad, G. M. January 1970 (has links)
Thesis (Ph. D.)--University of Wisconsin--Madison, 1970. / Typescript. Abstract: leaves iii-v. Includes computer source code in Fortran. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 215-219).
2

Modeling of Renewable Resources in Distribution System Planning and Operation

Alotaibi, Majed January 2014 (has links)
In recent decades, interest in placing renewable resources in conventional power systems has increased because of their ability to reduce fossil fuel consumption, which leads to the preservation of the environment. The rapid increase in employing these renewable resource-based DGs drives the system to be more dynamic, and causes many obstacles that need to be overcome. Power system planners and operators should look at the distribution system from another angle, taking into consideration the intermittent behavior of most renewable resources. Furthermore, solid models that are able to handle the uncertainty in generation levels are required. This thesis presents a comprehensive probabilistic model for representing renewable energy resources in long term planning problems. This model utilized large historical data sets, grouping technique, and statistical analysis in order to handle the fluctuations that are caused by the variations in wind speed or solar irradiance. In this research, renewable resources (wind and PV based DGs) ae well as dispatchable units are optimally allocated and sized using a probabilistic optimization model. This model incorporates the intermittent nature of wind speed and solar radiation into the deterministic optimal power flow equations. The variability from the load side and the uncertainty from the feeding side are considered. Genetic algorithm is used in order to minimize the annual energy losses of a distribution system. This thesis proposes a new iterative-based optimization algorithm is proposed in order to determine the minimum number of states that can precisely describe or represent the behavior of wind speed and solar irradiance in operational planning problems. This algorithm is evaluated using a power system planning problem. The proposed algorithm takes into account the annual energy losses and the total DG penetration level and considers them as an indication of how far the proposed method's outcomes are from the actual results. Three di fferent data groupings are applied (hourly, seasonally, and yearly) to investigate the variety of weather and electricity demands on the proposed method. The obtained results should be maintained within an acceptable limit of error which is in this thesis, 2:5%, and any violation of this limit will interrupt the algorithm sequences. The importance of this method actually lies in its ability to reduce the complexity in reliability analysis such that the number of overall system states will be minimized when the analytical evaluation methods are utilized.
3

Management Tool for Assessment of Alternative Fuel Cycles

Preston, Jeffrey R 01 August 2010 (has links)
A new approach to fuel cycle uncertainty analysis and optimization is presented that combines reactor physics information, spent fuel management, and economic forecasting, which may be used to investigate effects of decisions in the design of advanced nuclear fuel cycles. The Matlab-based simulation includes isotopic mass and integral decay heat data produced by reactor physics codes in the SCALE package (SAS2, ORIGEN-ARP, and ORIGEN-S). Reactor physics data for Light Water Reactor (LWR), and metal- and oxide-fueled Liquid Metal-cooled Fast Burner Reactor (LMFBR) designs are stored in databases that the code uses as needed. Detailed models of the once through and hybrid LWR-LMFBR fuel cycles have been developed for repository decay heat analysis, determination of levelized unit electric cost (LUEC), and reprocessing of spent fuel into fast reactor fuel or targets as a means of isotopic inventory minimization. The models may be run for single estimates based on best estimates of model parameters as either a Monte Carlo uncertainty analysis or as an optimization using Genetic Algorithms (GA). Results from the LUEC calculations show the once through cycle has a bus bar cost of about $19.0mills/kWh (excluding repository and interim storage costs), and the hybrid cycle has a bus bar cost of about $26.5mills/kWh. Implementation of the hybrid cycle compared to the closed once through cycle yields an effective repository mass capacity increase by a percentage of about 30% to 60% through full reprocessing of LWR spent fuel compared to original mass definitions of the Yucca Mountain repository. The GA optimization routine allows the user to define any one of the variables present in the output structure as the fitness parameter; thus, optimization of any calculated value is possible, including economic cost, isotopic inventory, or required repository capacity. Optimization of the once through cycle with respect to LUEC gives a result of $19.2 mills/kWh when burn up approaches the upper limit of 60 GWd/t and delay time spent fuel cools after discharge approaches 200 years (including repository and interim storage costs).
4

Energideklaration- Vad är det och hur ska det hanteras i fastighetsbranschen?

Gustafsson, Bert January 2006 (has links)
Abstract The Energy Declaration is a law that will come into effect October 1: Th 2006. This report has Värnamo municipality as principal and shall clarify what the estate owner in general and Värnamo municipality in particular need to know about this law. Another part that is going to be dealt with is how large the future need for energy experts in this field will be, and which competence that will be demanded for them. The work will in general deal with simplified energy declarations for apartment houses and public buildings, since these buildings are the first to be involved with energy declarations. The energy declaration will consist of a number of important components. • Energy power i.e. how much energy the building consume • If the ventilation control is done • If the radon measurement is carried out • Recommendations of measures to improve the energy power • Reference value to compare the buildings energy power against According to the law the declaration shall been made by an independent expert, which will need certain information for this. The estate owner will need to collect some of this information. To simplify the collection of information a model was developed that can be used by the estate owner. The model was tested on Trälleborgskolan in Värnamo. It worked well because energy statistics were available from Värnamo municipality estate department. Regarding the energy consumption monthly statistics were also available which was desirable. Some improvement can been made by correlate the heat consumption for a normal year. There will be an estimated need for about 500-1000 energy experts to work with energy declarations in the future. The requirements on these experts are apart from the right education, also a couple of years of experience from the energy business. This can be hard to fulfil for a newly examined engineer. This report focuses on the simplified energy declaration. In a couple of years when building will need to be inspected more thoroughly, there might be a need for more information to be collected. How this can be done in the different estate management computer software that are available, could be a base for future work in this area.
5

Energideklaration- Vad är det och hur ska det hanteras i fastighetsbranschen?

Gustafsson, Bert January 2006 (has links)
<p>Abstract</p><p>The Energy Declaration is a law that will come into effect October 1: Th 2006. This report has Värnamo municipality as principal and shall clarify what the estate owner in general and Värnamo municipality in particular need to know about this law. Another part that is going to be dealt with is how large the future need for energy experts in this field will be, and which competence that will be demanded for them.</p><p>The work will in general deal with simplified energy declarations for apartment houses and public buildings, since these buildings are the first to be involved with energy declarations.</p><p>The energy declaration will consist of a number of important components.</p><p>• Energy power i.e. how much energy the building consume</p><p>• If the ventilation control is done</p><p>• If the radon measurement is carried out</p><p>• Recommendations of measures to improve the energy power</p><p>• Reference value to compare the buildings energy power against</p><p>According to the law the declaration shall been made by an independent expert, which will need certain information for this. The estate owner will need to collect some of this information. To simplify the collection of information a model was developed that can be used by the estate owner.</p><p>The model was tested on Trälleborgskolan in Värnamo. It worked well because energy statistics were available from Värnamo municipality estate department. Regarding the energy consumption monthly statistics were also available which was desirable. Some improvement can been made by correlate the heat consumption for a normal year.</p><p>There will be an estimated need for about 500-1000 energy experts to work with energy declarations in the future. The requirements on these experts are apart from the right education, also a couple of years of experience from the energy business. This can be hard to fulfil for a newly examined engineer.</p><p>This report focuses on the simplified energy declaration. In a couple of years when building will need to be inspected more thoroughly, there might be a need for more information to be collected. How this can be done in the different estate management computer software that are available, could be a base for future work in this area.</p>
6

Coordinated control and network integration of wave power farms

Nambiar, Anup Jayaprakash January 2012 (has links)
Significant progress has been made in the development of wave energy converters (WECs) during recent years, with prototypes and farms of WECs being installed in different parts of the world. With increasing sizes of individual WECs and farms, it becomes necessary to consider the impacts of connecting these to the electricity network and to investigate means by which these impacts may be mitigated. The time-varying and the unpredictable nature of the power generated from wave power farms supplemented by the weak networks to which most of these farms will be connected to, makes the question of integrating a large quantity of wave power to the network more challenging. The work reported here focuses on the fluctuations in the rms-voltage introduced by the connection of wave power farms. Two means to reduce these rms-voltage fluctuations are proposed. In the first method, the physical placement of the WECs within a farm is selected prior to the development of the farm to reduce the fluctuations in the net real power generated. It is shown that spacing the WECs or the line of WECs within a farm at a distance greater than half the peak wavelength and orienting the farm at 90◦ to the dominant wave direction produces a much smoother power output. The appropriateness of the following conclusions has been tested and proven for a wave power farm developed off the Outer Hebrides, using real wave field and network data. The second method uses intelligent reactive power control algorithms, which have already been tested with wind and hydro power systems, to reduce voltage fluctuations. The application of these intelligent control methods to a 6 MW wave power farm connected to a realistic UK distribution network verified that these approaches improve the voltage profile of the distribution network and help the connection of larger farms to the network, without any need for network management or upgrades. Using these control methods ensured the connection of the wave power farm to the network for longer than when the conventional control methods are used, which is economically beneficial for the wave power farm developer. The use of such intelligent voltage - reactive power (volt/VAr) control methods with the wave power farm significantly affects the operation of other onshore voltage control devices found prior to the connection of the farm. Thus, it is essential that the control of the farm and the onshore control devices are coordinated. A voltage estimation method, which uses a one-step-ahead demand predictor, is used to sense the voltage downstream of the substation at the bus where the farm is connected. The estimator uses only measurements made at the substation and historical demand data. The estimation method is applied to identify the operating mode of a wave power farm connected to a generic 11 kV distribution network in the UK from the upstream substation. The developed method introduced an additional level of control and can be used at rural substations to optimise the operation of the network, without any new addition of measuring devices or communication means.
7

Aktyviosios ir reaktyviosios galių režimų valdymas restruktūrizuotoje elektros energetikos sistemoje / Active and reactive power control in restructured electrical energy system

Šulga, Dalius 25 July 2005 (has links)
The main objective of the Thesis is to work out the methodology aimed to develop a closely integrated electricity network model to be used for real time calculations, and afterwards, based on this methodology, to develop a model of a closely integrated electricity network, which would be applicable in real time calculations of active and reactive power.
8

Generation of wind speed and solar irradiance time series for power plants with storage

Mauger, Léo January 2016 (has links)
Sizing renewable energy power plants with storage devices needs new resource assessment. Global amount of energy available has to be replaced by time series to depict the resource as a function of time. This paper introduces methodology to generate time series for wind speed and solar irradiance with a granularity between 10minutes and 1seconde. Ground measurements and macro-date from satellite imagery are analyzed and processed to obtain long-term site-specific time series. Because renewable energy forecasting is a growing concern, a second part of the work presents how to modify previously generated profiles in order to obtain forecasts with an expected error.
9

Offshore-Windenergie zur Stromerzeugung

Viertel, René, Tetzlaff, Gerd, Kaltschmitt, Martin 31 January 2017 (has links)
Der mittlere Wind in der atmospärischen Grenzschicht über den deutschen Nord- und Ostseegebieten unterscheidet sich gegenüber Landflächen durch höhere Windgeschwindigkeiten, eine stärkere Zunahme mit der Höhe und schwache Tages- sowie ausgeprägte Jahresgänge der Windgeschwindigkeit in Bodennähe. Neben diesen Vorteilen ergeben sich auch Nachteile im Hinblick auf die Windenergienutzung offshore. Das betrifft die Anforderungen an die Technik der Windstromerzeugung sowie wie die Messung und Prognose der relevanten meteorologischen Parameter. Nach Abschätzungen möglicher Flächen für die Windnutzung offshore und anlagentechnischer Möglichkeiten ist von einem enormen technischen Angebotspotenzial an Elektroenergie auszugehen, dem jedoch auch Beschränkungen seitens der Netzstruktur und Nachfrage entgegenstehen. Um das große Potenzial zur Stromerzeugung und Umweltentlastung nutzen zu können, sollte die Entwicklung in den kommenden Jahren im Bereich Windprognose, Anlagenbau, Regelungstechnik und Energiespeicherung zu weiteren Verbesserungen führen. / The averaged wind in the Planetary Boundary Layer over the german North Sea and Baltic Sea areas shows some differences to the wind over land areas. There are higher wind speeds, a stronger increasing with height and slight daily and more distinctive annual variations of the near surface winds. Thats why the utilization of wind energy offshore has advantages. But also exists certain drawbacks in reference to technical requirements and the measurement and prediction of meteorological parameters. Estimations of suitable areas and technical prospects indicate a large technical offer potential of electric energy offshore, though additional restrictions must be considered. To make this potential of electric energy and environmental protection usable todays knowledge of systems and control engineering, energy storage and wind prediction should be improved in the coming years.
10

Bewertung von Anlagen zur Kraft-Wärme-Kopplung

Zschernig, Joachim, Sander, Thomas 17 January 2008 (has links)
Die Anwendung der Kraft- Wärme-Kopplung (KWK) führt zur Brennstoffeinsparung gegenüber der getrennten Bereitstellung von Elektroenergie und Heizwärme und ist daher ein wesentliches Instrument zur Senkung der CO2- Emissionen. Folglich strebt die EU das Ziel an, die Stromerzeugung aus KWK zu verdoppeln. Zur Bewertung der Effizienz werden jedoch oft Methoden angewendet, die dem Prozess nicht gerecht werden. Weitere Probleme sind die korrekte Definition des Stromes aus KWK, d. h. die physikalisch begründete Unterteilung der gelieferten Elektroenergie in einen gekoppelt und einen ungekoppelt bereitgestellten Anteil, sowie die Aufteilung des benötigten Brennstoffs auf Elektroenergie und Wärme. Der Beitrag schildert ausgehend von den bestehenden Problemen einen Lösungsvorschlag für eine objektive Bewertung. / The co-generation of heat and power (CHP) reduces fuel consumption in comparison with the separate production of heat and power. CHP is thus an important instrument for the reduction of CO2 emissions. Consequently, it is the ambition of the European Union to double the share of CHP in power generation. The methods applied for the assessment of CHP efficiency, however, are often inappropriate. Further problems are accurate definition of the power from CHP and assignment of the fuel consumption to the generated power and heat. Based on the existing problems, the paper offers suggestions for an objective assessment.

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