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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.
761

Analysis of Demand Response Solutions for Congestion Management in Distribution Networks

Brodén, Daniel January 2013 (has links)
According to the 20-20-20 targets set by the European Union, 50 percent of the Swedish electricity share is to be provided by renewable energy sources by 2020. The Smart Grid Gotland (SGG) project has emerged as a response to this target. The project aims at demonstrating a proof of concept on how smart grid solutions can be used to integrate large quantities of renewable energy sources in an existing network. The outcomes of the project are intended to pave the way for future renewable energy integration projects in Sweden. The Thesis focuses on one of the technical objectives of the SGG project, i.e. to increase the hosting capacity of wind power on Gotland from 195 MW to 200 MW by using Demand-Response (DR) from households and industries. DR consist of shifting peak-loads to peakproduction hours. The integration of additional wind power causes a risk of exceeding the transmission capacity of the power export cable between Gotland and the Swedish mainland. The approach considered for this Thesis is to use an Ancillary Service (AS) toolbox scheme based on multi-agent systems. The AS toolbox consist of flexibility tools such as DR on long-term, short-term, a battery energy storage system and a wind curtailment scheme. The DR activity includes space heating and domestic hot water consumption from detached houses on Gotland. The simulation results indicate that 1900 household participants are sufficient to balance the additional 5 MW for worst case scenarios. Furthermore, it is shown that the DR participation from industries contributes in some cases to a reduction of 700 household participants. The findings helped conclude that using an AS toolbox solution on Gotland is fully possible from a technical perspective. However, barriers that stand against its realisation are of economical nature and need to be investigated in future studies.
762

Wind Power in Areas with Limited Export Capability

Matevosyan, Julija January 2004 (has links)
During the last two decades, increase in electricity demand and environmental concern resulted in fast growth of power production from renewable sources. Wind power is one of the most efficient alternatives. Due to rapid development of wind turbine technology and increasing size of wind farms, wind power plays a significant part in the power production mix of Germany, Spain, Denmark and some other countries. Wind power has to be built in areas with good wind potential. The best conditions for installation of wind power are, thus, in remote areas free of obstacles, and consequently with low population density. The transmission system in such areas might not be dimensioned to accommodate additional large-scale power plants. Insufficient transmission capacity problem, however, would emerge for any type of new generation, planned in similar conditions, although wind power has some special features that should be considered solving this problem. In this thesis the four possibilities are considered. One possibility is to revise the methods for calculation of available transmission capacity. Another solution for large-scale integration of wind power in such areas is to reinforce the network. This alternative however may be expensive and time consuming. Since wind power production depends on the wind speed, the wind farm utilization time is only 2000-4000 hours a year, and power production peaks not necessarily occur during periods with insufficient transmission capacity. Therefore wind energy curtailment may be considered as an alternative for large-scale wind power integration. It is also possible to store excess wind energy during the periods with insufficient transmission capacity. Conventional power plants with possibilities of fast production control (e.g. hydro power plants or gas power plants) may also be employed for this purpose. There is a lot of research regarding first two measures, therefore, this thesis provides a review and summarized conclusions from the existing work and further concentrates on development of the methods for estimation of wind energy curtailment and evaluation of wind energy storage possibility in hydro reservoirs. Methods similar to probabilistic production cost simulation are developed for estimation of wind energy curtailment. The developed methods are applicable to discrete variables (measurements) and also generalized for continuous variables with known distribution. For evaluation of wind energy storage possibility the optimization problem is formulated, the objective of this evaluation is to minimize the costs for power production under consideration of the future water value. The developed method allows us to analyze previous years of operation of the power system (e.g. dry, wet and normal year) and evaluate physical possibilities for wind energy storage. The developed methods are than tested for Swedish power system and the results are also summarized in this thesis. / <p>QC 20100607</p>
763

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.
764

Vindkraftsturism : En studie av teknisk turism med särskilt fokus på vindkraftsparker

Natanaelsson, Anna January 2014 (has links)
This study investigates and describes the phenomenon of ‘technical tourism’, in the case of wind power plants in Sweden. The main purpose of the study is a greater understanding of a field which to date has remained largely uncharted. Technical tourism is a type of visits to a production site, where the technical aspect of the production is the main focal point for the visitor. The definition of technical tourism is based on concepts within ‘Industrial tourism’. Technical tourism is argued to be a subcategory of Industrial tourism. The study, conducted in collaboration between KTH and Vattenfall, resulted in two complementing parts. Part one, ’Vinkraftsturism: En studie av teknisk turism med särskilt fokus på vindkraftsparker’, is a theoretical description of technical tourism (hereafter referred to as ‘Rapporten’). Part two, ‘Kommunikationsmanual: Vindkraftsturism’, a communications manual based on the results of the study and tailored for Vattenfall to use when informing various stakeholders about technical tourism (hereinafter ‘Manualen’). Material for the two parts of the thesis was gathered through interviews and literature reviews. The informants where gathered in and around one single wind park in northern Sweden. Stakeholders from both the municipality and local/regional businesses were included in the study. ‘Rapporten’ — The theoretical review of technical tourism in a wind power plant deals with benefits and conflicts which may occur when interfacing with the local community and other stakeholders. A model for stakeholder assessment is presented and used to find key relationships between involved parties. It further describes the importance of cooperation and finding common points of identification between the host company and the region. Two factors which are needed to efficiently establish technical tourism. ‘Manualen’ — The communications manual is designed with the characteristic democratic perspective of ‘Education for sustainable development’. Furthermore it presents a workshop structure and a summary of similar projects both national and international. The study showed a variety of benefits (five of them) from technical tourism, and also some potential conflicts. The study also highlighted the importance of collaboration between stakeholders, both through the informants’ statements and explored in previous academic works. It also states that the democratic process and the participants’ view of themselves as democratic subjects, are important factors when communicating technical tourism. The study presents a new definition of technical tourism. / Den här studien undersöker och beskriver fenomenet ”teknisk turism” för vindkraftparker i Sverige. Huvudsyftet med studien är en djupare förståelse för ett nytt forskningsfält som till stor del lämnats outforskat. Teknisk turism är en typ av besök i en verksamhetsanläggning, där de tekniska aspekterna av produktionsprocessen är huvudfokus för besökaren. Definitionen av teknisk turism baseras på konceptet ”Industrial tourism”. Teknisk turism hävdas vara en underkategori till Industrial tourism. Studien, som är ett samarbete mellan KTH och Vattenfall, har resulterat i två sammanhängande delar. Del ett, ‘’Vindkraftsturism: En studie av teknisk turism med särskilt fokus på vindkraftsparker’, är en teoretisk beskrivning av teknisk turism (nedan kallad ‘Rapporten’). Del två, ‘Kommunikationsmanual: Vindkraftsturism’ är en handledande kommunikationsmanual baserad på resultaten i studien, designad för Vattenfall att använda vid information om teknisk turism till berörda intressenter (nedan kallad ‘Manualen’). Materialet för de två delarna av studien samlades genom intervjuer och genom litteraturstudier. Informanterna rekryterades i anslutning till en vindkraftspark i norra Sverige. Representanter från kommunen samt det lokala näringslivet inkluderades i studien. ‘Rapporten’ – Den teoretiska genomgången behandlar potentiella möjligheter och konflikter för berörda intressenter, som kan uppstå kring en vindkraftspark med besökarverksamhet. Vidare presenteras och används en modell för analys av intressenter, för att finna nyckelrelationer mellan involverade parter. Den beskriver även vikten av att finna gemensamma identifikationspunkter och samverkan mellan värdföretaget och regionen. Två faktorer som är nödvändiga för en effektiv etablering av teknisk turism. ‘Manualen’ – Kommunikationsmanualen är utformad efter det demokratiperspektiv som karaktäriserar ’Education for sustainable development’. Den består av en färdig mall för en workshop på ämnet och även en redovisning av besöksprojekt av liknande karaktär, både från Sverige och internationellt. Resultatet visar en handfull fördelar med teknisk turism och även några potentiella konflikter. Studien belyser även vikten av samverkan mellan intressenterna, något som framkommit både via informanter och genom granskning av tidigare forskning. Studien presenterar en ny definition av teknisk turism.
765

Business Models for an Aggregator : Is an Aggregator economically sustainable on Gotland?

Lambert, Quentin January 2012 (has links)
Under the determined impulse of the European Union to limit the environmental impact of energy-related services, the electricity sector will face several challenges in coming years. Integrating renewable energy sources in the distribution networks is certainly one of the most urging issues to be tackled with. The current grid and production structure cannot absorb the high penetration shares anticipated for 2020 without putting at risk the entire system. The innovative concept of smart grid offers promising solutions and interesting implementation possibilities. The objective of the thesis is to specifically study the technical and economic benefits that the creation of an aggregator on the Swedish island of Gotland would imply. Comparing Gotland's power system characteristics to the broad variety of solutions offered by demand side management, wind power integration enhancement by demand response appeared particularly suited. A business case, specifically oriented towards the minimisation of transmission losses by adapting the electric heat load of private households to the local wind production was designed. Numerical simulations have been conducted, evaluating the technical and economic outcomes, along with the environmental benets, under the current conditions on Gotland. Sensitivity analyses were also performed to determine the key parameters for a successful implementation. A prospective scenario for 2020, with the addition of electric vehicles, has finally been simulated to estimate the long term profitability of an aggregator on the island. The simulation results indicate that despite patent technical benefits for the distribution network, the studied service would not be profitable in the current situation on Gotland. This, because the transmission losses through the HVDC-cable concern limited amounts of power that are purchased on a market characterized by relatively cheap prices and low volatility. Besides, the high fixed costs the aggregator has to face to install technical equipment in every household constitutes another barrier to its setting up.
766

Feasibility Study of Renewable Energy in Singapore

King, Sebastian, Wettergren, Per January 2011 (has links)
Singapore is a country that is currently highly dependent on import of oil and gas. In order to be able to shift into a more sustainable energy system, Singapore is investing in research regarding different technologies and systems so as to establish more sustainable energy solutions. Seeing how air-conditioning accounts for approximately 30 % of Singapore’s total energy consumption, a feasibility study is being conducted on whether an integrated system using a thermally active building system (TABS) and desiccant evaporative cooling system (DECS) can replace the air-conditioning system. The question which is to be discussed in this thesis is whether solar and wind power can be financially feasible in Singapore and if they can be utilized in order to power the integrated system.   The approaching model consists of a financial feasibility study of the different technologies and a theoretical test-bedding, where the suitability of the technologies to power the TABS and DECS is tested. The financial feasibility is estimated by calculating the payback period and using the net present value method. A model designed in a digital modeling software is used for the test-bedding. Measurements from a local weather station are used for estimating the solar radiance and wind speeds in Singapore. The results show that solar PV panels could be feasible in Singapore but that technological improvements as well as governmental subsidies are needed in order to make it profitable enough to attract investors. As for wind power, the wind conditions are not favorable enough, in terms of wind speed and wind frequencies, for small wind turbines that currently exist on the market to be able generate enough electricity to make the investment somewhat feasible. Solar thermal collectors and solar PV are given certain conditions suitable for powering the TABS and DECS.
767

Temperaturinverkan på komponenter i vindkraftverk : En förstudie åt Arise AB / Temperature impact on components in wind turbines : A prestudy for Arise AB

Bjuringer, David, Sjölander, Alfred January 2021 (has links)
This thesis aims to analyze how different temperature deviations affect the components of wind turbines. A study of the temperatures in several different components was carried out to get a clearer picture of how these affects operational reliability. By trying to link, for example, extreme values of temperatures to possible alarms and downtime in the wind power plants, the hope is that this study will be able to contribute to safer and more maintenance-free wind turbines in the future. The 12 wind turbines that have been evaluated in this study are localized in southern Sweden. The time period for the collected data extends over 6 years. In the thesis, an analysis has been carried out with the help of the computer program Matlab to examine different types of data collected from the components in the wind turbines. The data was plotted with the help of various functions in Matlab and with the help of mathematical equations. The data was then observed ocularly by the authors, which led to the discovery of different connections between temperature variations in the components and different error codes. The generator bearing was the component that was found to have the highest correlation between temperature deviations and specific error codes related to various yaw-errors, which can be explained as error codes that occur when the wind turbine fails to adjust itself to the wind. An analysis has also been made to determine whether there was a temperature-related upward trend in any of the components in the wind turbines. This was carried out with the help of various standard deviation calculations and calculation of the mean temperature value of different components. The standard deviation in this case describes how much the temperature of each component varies from the mean value. It turned out that there was such an upward trend for the Generator Bearing and Generator Phase 3 components. Some turbines also turned out to have a more distinct upward trend than others
768

Elnät eller off-grid : Ur ett hållbarhetsperspektiv

Sassersson Busadee, Nelly January 2020 (has links)
All types of electricity production have a negative impact on the environment, the most sustainable electricity is the one that never has been produced. If the West is to continue living with electricity and at the same time try to reduce the carbon footprints, there must be a change. In order to increase the use of renewable energy, off-grid installations are currently being produced for those houses that are far from civilization. But if you can connect to the grid electricity, what option is best from a sustainability perspective? This project therefore examines the possibilities for energy alternatives and aims to explore which option is most environmentally friendly based on the resources offered by the environment on Bornholm. Based on previous research and data, the conditions for electricity from the grid and an off-grid combination, are examined. The study begins with an in-depth literature study that deals with site data, technical aspects and life-cycle assessments of the energy alternatives that today can be used on Bornholm. Built on the analyses and measurements made on Bornholm's electrical mix and the off-grid system that works best given the conditions that the site has, it is concluded that electricity from the electricity grid is affecting the environment the least. / All elproduktion har en negativ inverkan på miljön. Det mest hållbara är att inte producera någon el. Om världen ska fortsätta leva med elektricitet och samtidigt försöka reducera koldioxidavtrycken måste det ske en förändring. För att öka användningen av förnybar energi tillverkas idag off-grid installationer för de hus som ligger långt från civilisationen. Om det finns möjlighet att ansluta till elnätet, vilket alternativ är då bäst ur ett hållbarhetsperspektiv? I detta projekt undersöks därför möjligheterna till olika energialternativ för trädtoppshus på Bornholm. Målet är att försöka bena ut vilket alternativ som är miljövänligast utifrån de resurser som omgivningen erbjuder. Utifrån tidigare forskning och data undersöks förutsättningarna för el dragen från elnätet, och el från en off-grid kombination. Studien börjar med en djupgående litteraturstudie som behandlar platsdata, tekniska aspekter och livscykelanalyser av de energialternativ som idag kan brukas på Bornholm, samt på olika typer av off-grid alternativ. Utifrån de analyser och mätningar som gjorts på Bornholms elmix, och det off-grid system som fungerar bäst med tanke på de förutsättningar som platsen erbjuder, blir slutsatsen att el från elnätet är det som påverkar miljön minst.
769

The Nuclear Option : A Global Sustainability Appraisal of Civil Nuclear Energy

Arnström, Sebastian January 2020 (has links)
Energy production systems are essential for human progress. They fuel the technologies that underpin economic growth and are prerequisite for efficient food production, education and healthcare. On the flip side, they also incur substantial eco-social costs. Hence, finding and promoting sustainable means of energy production is a key topic within the Environmental Sciences. This thesis examines the sustainability of nuclear power, by comparing its social, economic and ecological impacts to those of wind and solar power. The assessment is performed using Multi-Criteria Analysis (MCA), with a Weighted Sum scoring system and a Distance-To-Target weighting scheme. The selection and the weighting of the indicators are grounded in the Planetary Boundaries framework, the Oxfam Doughnut Economics model and the UN’s Sustainable Development Goals, and the technologies are compared on 9 axes of evaluation; greenhouse gas emissions, land-take requirements, material throughput, non-recyclable wastes, toxic and radioactive wastes, negative health impacts, economic costs, intermittency and energy return on energy invested. The thesis finds nuclear power to be the most sustainable option according to all but three indicators, and in the unified analysis, it outcompetes wind and solar by a factor of 2 and 3 respectively. Also notable is that solar power does not excel in a single impact category; it has the highest greenhouse gas emissions, the largest land-take, and it is costly, intermittent and energy-inefficient. It is also a source of toxic pollution, the effects of which cannot yet be determined. Although wind is more competitive, it consumes vast amounts of physical resources, generates a lot of waste, and its land-take is at least 10 times higher than that of nuclear power. In addition to the MCA, the thesis investigates three perceived threats that are often raised in criticisms of nuclear power; the risk of nuclear fuel depletion, the risk of nuclear weapons proliferation and the risk of catastrophic nuclear accidents. The results show that many popular arguments against the technology are loosely aligned with reality, and the thesis as a whole presents a challenge to the notion that nuclear power is a dangerous and unsustainable energy source.
770

Extending Technology Roadmap through Fuzzy Cognitive Map-based Scenarios: The Case of the Wind Energy Sector of Pakistan

Amer, Muhammad 09 May 2013 (has links)
In this modern era, energy is a key element required for sustainable development and prosperity of a society. Pakistan is an energy deficient country facing problems due to the shortage of over 4000 MW of electricity. The national energy sector is heavily dependent on imported fossil-fuel resources. The energy crisis is negatively affecting all economic and business activities, and it is widely recognized as a severe obstacle to growth and poverty reduction in the country. Establishment of wind farms can help to overcome the energy crisis. In this research, a national level wind energy roadmap is developed through scenario planning. Multiple future scenarios are developed using the fuzzy cognitive maps (FCM) approach. This research has extended technology roadmapping through FCM-based scenario analysis. Building scenarios with FCM is a very new approach, and for the first time FCM-based scenarios are developed for the wind energy sector of Pakistan. Based on these multiple scenarios, a technology roadmap has been developed. This research approach is applied to the wind energy sector of Pakistan as a case study. This approach has been used to establish objectives and national targets of the roadmap. Then in a systematic way, critical roadmap barriers are identified against each scenario, and appropriate action items have been proposed to overcome barriers and promote deployment of wind energy projects in Pakistan. The objectives and targets of the roadmap have been translated into action items. The technology roadmap has four layers: strategic objectives, targets, barriers, and action items. Expert panels have been utilized to develop scenarios and technology roadmaps. Validation of this research is also carried out using experts. This new approach has helped to develop a robust roadmap and enabled anticipation of a wide range of possible future outcomes. This research fills an important gap by combining scenario planning and technology roadmapping techniques in future studies, and it has enhanced flexibility of the developed roadmap. Moreover, for the first time multiple and plausible FCM-based scenarios are developed, which combine the benefits of both qualitative and quantitative analysis. Moreover, the technology roadmap for the wind energy sector of Pakistan is developed with a comprehensive study of practical obstacles and barriers towards deployment of wind energy technology. The research findings suggest that policy, financial, economic, lack of competition with conventional power plants, and technical are the most critical barriers towards deployment of wind energy projects in the country. Appropriate action items required to overcome the roadmap barriers against each scenario are also proposed in the developed roadmap. The experts also assigned responsibilities for the key roadmap action items to the major stakeholders.

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