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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.
81

Optimization of Distribution Systems: Transactive Energy and Resilience Enhancement

Qi, Chensen 21 May 2024 (has links)
The increasing penetration of electric vehicles (EVs) and other distributed energy resources (DERs) offers enhanced flexibility and resilience. During extreme conditions, grid-connected EVs and DERs can provide electricity service and restore critical loads when the utility system is unavailable. On the other hand, during normal operation, these proactive devices can provide ancillary services to alleviate voltage fluctuations and support frequency regulation. In comparison with other DERs, EVs are more flexible in providing ancillary services due to their mobile nature. However, the proliferation of EVs and DERs also introduces operational challenges to the distribution grid. For instance, EVs primarily fulfill their transportation needs. Uncoordinated charging of a large number of EVs can increase the burden on the distribution system. Due to the limited charging rate and battery size, it is generally impractical for a single EV to directly participate in the ancillary service market. A conventional distribution system is designed for unidirectional flow of electric energy. With the growing installation of DERs on the distribution system, the flow of electric energy is bi-directional and, therefore, there is a higher risk of protection miscoordination due to the fault currents resulting from DERs. With limited communication capability, these undetected protective device (PD) actuations can cause uncertainties and delay the service restoration process. This dissertation makes contributions to the coordination of EVs and DERs. It introduces four innovative models for EV coordination: 1) A transactive energy (TE) trading mechanism is proposed to coordinate EVs and aggregators. 2) Optimal tools are provided to assist EVs and aggregators in optimal decision making while participating in TE. 3) A charging station model is developed to allow EVs to provide ancillary service aligned with their mobile nature. 4) A utility function model is presented to capture the EV owners' behaviors for providing ancillary services and charging vehicles. Charging stations can estimate the electric energy demand and optimize ancillary service provision to meet their goals. Simulation cases validated that the proposed optimization tools can align EV owners' preferences in providing ancillary service to enhance distribution system operation flexibility. To enhance the resilience of distribution systems, two novel optimization strategies are presented: 1) An advanced outage management (AOM) is proposed to utilize smart meters and fault indicators (FIs) to identify the most credible outage scenario and fault locations. 2) An advanced feeder restoration (AFR) is developed to provide an optimal restoration strategy to enhance system resilience. The proposed optimization models have been validated with realistic simulation cases. / Doctor of Philosophy / As Electric Vehicles (EVs) and other Distributed Energy Resources (DERs) become more common, they are changing how our distribution systems work. For example, during power outages, grid-connected DERs and EVs can be deployed to sustain essential electricity services such as hospitals and communications. On the other hand, during a normal operating condition, they can help maintain the stability of our electricity systems. It is a technical challenge to integrate these new EV and DER devices into the existing power grid. For example, EVs are mainly designed for transportation. Their clustered charging patterns can significantly increase the electrical demand if they are not managed properly. Also, the limited battery capacity and charging speed make it difficult for a single vehicle to provide meaningful support to the grid operation. For the EV management side, this research is concerned with how to better integrate EVs and similar technologies into the power grid. Four key contributions of this dissertation are: 1) Developing a trading mechanism for EVs and aggregators of EVs to exchange energy and ancillary services efficiently; 2) Creating computational technologies to help these entities optimize their decisions while meeting their requirements; 3) Structuring charging station operations that cater to the preferences of EV owners while supporting grid operation; and 4) Modeling EV owners' decision-making to set optimal pricing and service strategies at charging stations. These mechanisms and strategies will allow EV owners to support the power grid while meeting their transportation needs. Moreover, the study addresses the issue of enhancement of the distribution system's capability to restore services under extreme conditions. It provides an advanced outage management method that utilizes remote monitoring and control technologies, including smart meters and fault indicators, to identify the location of electrical faults and reduce the outage areas. The advanced feeder restoration method determines an optimal strategy to restore the electricity service efficiently while keeping the distribution grid stable.
82

Voltage Control Devices Coordination in Power Distribution Systems with High PV Penetration

Mahdavi, Shahrzad 01 January 2023 (has links) (PDF)
The penetration of renewable and distributed generation sources (DGs) in power distribution systems has been increasing at an ever-faster rate. While DGs provide clean and affordable energy, their addition introduces new problems in the system operation. One of the main challenges due to the high penetration of DGs is the overvoltage issues that demand appropriate voltage control. This control is essential to maintain the power quality, energy efficiency, and voltage stability in the system. Voltage Regulators (VRs) and capacitor banks (CBs) are traditional control devices that are installed in the system to keep the desired voltage profile. However, they are not designed to operate in a way that can address the high frequency and magnitude changes occurring in systems with high penetration of DGs. Therefore, they need to be supplemented with voltage control performed by controlling the reactive power generation of the DGs. The coordination among these different control devices is essential for proper system operation. This thesis explores the design of the coordinated control of VRs, CBs, and DGs, by considering different control methods such as coordinated cooperative, predictive cooperative, and unified control of all voltage control devices. The proposed methods are implemented in a system with high penetration of DGs and tested by exploring the worst-case scenario in terms of DG sizing and placement. This scenario is determined analytically using sensitivities and verified using stochastic Monte Carlo simulation. The future generation of active power distribution systems need to be optimally controlled in order to be efficient, reliable, and resilient, while capable of effectively managing high penetration levels of DGs, and other controllable loads and devices. The important outcome of this thesis is the introduction of a practical voltage control method to achieve these goals.
83

A legal framework for the promotion of renewable energy in South Africa through fiscal instruments / Michél Coetzer

Coetzer, Michél January 2014 (has links)
South Africa‟s current energy sector places undue reliance on fossil fuels to fulfil the country‟s energy requirements. The use of these non-renewable energy resources are unsustainable, as millions of tonnes of harmful emissions are released and estimates are made that these resources will be depleted within the next 100 years. Therefore the country has to source alternative energy resources. Renewable energy resources (for example solar energy) are considered to release little or no harmful by-products and have an infinite supply. Therefore the South African government has to promote the use of renewable energy as part of its commitments to address climate change and to ensure sustainable energy resources. Some of the most popular regulatory tools that a state uses to control human behaviour, is through command-and-control instruments and fiscal instruments. The latter promotes behavioural changes by rewarding desired behaviour which ultimately advances the user‟s own best interest. Because of the nature of renewable energy governance, energy users can not be forced or compelled through commandand- control instruments to use renewable energy. They should rather be encouraged or persuaded to use this form of energy through market-based instruments. This is also the central hypothesis of this dissertation. The purpose of this study is to determine the extent to which the South African legal regime makes provision to promote the use of renewable energy resources through fiscal instruments. Therefore the various energy-related white papers, policy papers and legislation will be analysed. This study found that South Africa‟s legal regime only partly makes provision to promote the use of renewable energy resources through fiscal instruments. The policy part of the legal regime is fairly well developed, but the statutory regime lacks detail and in its current form, environmental/energyrelated legislation does not fully correspond with the lofty objectives of the policy framework. / LLM (Environmental Law and Governance), North-West University, Potchefstroom Campus, 2015
84

A legal framework for the promotion of renewable energy in South Africa through fiscal instruments / Michél Coetzer

Coetzer, Michél January 2014 (has links)
South Africa‟s current energy sector places undue reliance on fossil fuels to fulfil the country‟s energy requirements. The use of these non-renewable energy resources are unsustainable, as millions of tonnes of harmful emissions are released and estimates are made that these resources will be depleted within the next 100 years. Therefore the country has to source alternative energy resources. Renewable energy resources (for example solar energy) are considered to release little or no harmful by-products and have an infinite supply. Therefore the South African government has to promote the use of renewable energy as part of its commitments to address climate change and to ensure sustainable energy resources. Some of the most popular regulatory tools that a state uses to control human behaviour, is through command-and-control instruments and fiscal instruments. The latter promotes behavioural changes by rewarding desired behaviour which ultimately advances the user‟s own best interest. Because of the nature of renewable energy governance, energy users can not be forced or compelled through commandand- control instruments to use renewable energy. They should rather be encouraged or persuaded to use this form of energy through market-based instruments. This is also the central hypothesis of this dissertation. The purpose of this study is to determine the extent to which the South African legal regime makes provision to promote the use of renewable energy resources through fiscal instruments. Therefore the various energy-related white papers, policy papers and legislation will be analysed. This study found that South Africa‟s legal regime only partly makes provision to promote the use of renewable energy resources through fiscal instruments. The policy part of the legal regime is fairly well developed, but the statutory regime lacks detail and in its current form, environmental/energyrelated legislation does not fully correspond with the lofty objectives of the policy framework. / LLM (Environmental Law and Governance), North-West University, Potchefstroom Campus, 2015
85

Endependence: renewable energy in a rural community / Independence: renewable energy in a rural community

Schuette, Krystal M. January 1900 (has links)
Master of Landscape Architecture / Department of Landscape Architecture/Regional and Community Planning / Mary C. Kingery-Page / Rural Kansas communities are almost entirely dependent on large energy corporations. These corporations, in turn, are almost completely dependent on fossil fuels for energy production. Three major implications exist within these dependencies: 1) the dependence of rural communities on large corporations reduces the potential of a local economy to support itself; 2) the dependence on fossil fuels has severe environmental impacts; and 3) fossil fuels are non-renewable resources and will inevitably be exhausted. A rural Kansas community has resources necessary to achieve and maintain energy independence in a renewable manner. The design of these systems in regard to economy, society, aesthetics, technology, and ecology will play a key role in sustaining these resources into the future. The intent of the project is to create a tool for rural communities to evaluate localized renewable energy potential using Washington, Kansas as an example. Several questions were addressed to determine the capacity and feasibility of each local energy resource: What renewable energy resources are available to a rural Kansas community and are they sufficient for the community to achieve energy independence? How can the resource or its production be designed and maintained in regard to its environmental impact and long-term viability? What are the implications of energy independence for the community’s identity? Because each question is dependent upon the answer to a previous question, a decision tree was the most viable method for the project’s analysis and development. Research into the technology and science associated with each resource provided a general knowledge of the definitions associated with and processes necessary to determine the feasibility of the resource. For resources receiving a positive feasibility rating, analysis continued with a basic cost/benefit analysis that compares potential costs involving implementation and maintenance with the payback, offsets, and incentives involved in utilizing each resource. Analysis of each feasible resource continued with site suitability analysis. The analysis of each resource resulted in resource maps showing potential implementation locations for three renewable resources studied: hydro, wind, and solar. The maps and accompanying graphics communicate the integration of renewable energy technologies into the existing community’s identity.
86

Modelling and verification of the dynamics of an ocean current energy converter

Graaff, Simon 12 1900 (has links)
Thesis (MScEng) -- Stellenbosch University, 2014. / ENGLISH ABSTRACT: South Africa has a signi cant potential resource for electrical power generation in the Agulhas Current on the southeast coast. The Ocean Current Energy Convertor studied in this project was designed to generate power from this current. The feasibility of this device was investigated by analysing the dynamic stability and controllability of the convertor, when acted upon by hydrodynamic forces while harvesting energy from the current. A simulation model was developed to predict the dynamic behaviour using the Simulink software suite. A scale model of the prototype was built and tested in the Towing Tank at Stellenbosch University, and the experimental results were compared against the simulation results. A control algorithm was designed, using the mathematical model, to control the roll angle and deployment depth. The control algorithm was tested in simulation. The results indicated that the simulation model accurately predicted the behaviour of the prototype in testing, and results showed that the device is both stable and controllable. It was concluded that this OCEC design concept warrants further investigation. The recommendations are that the experimental model be improved to ensure reliable experimental results, that further complexity be added to the simulation model, and that the control algorithm be tested on the improved prototype in the towing tank. / AFRIKAANSE OPSOMMING: Die Agulhas-seestroom aan die suidooskus van Suid-Afrika bied 'n aansienlike potensiële hulpbron vir elektriese kragopwekking. Die seestroomenergieomsetter (SEO) wat in hierdie projek bestudeer is was ontwikkel om krag uit hierdie seestroom te genereer. Die doenlikheid van hierdie toestel is ondersoek deur die dinamiese stabiliteit en beheerbaarheid van die omsetter onder die invloed van hidrodinamiese kragte te analiseer terwyl dit energie van die stroom inwin. 'n Simulasiemodel is met behulp van Simulink-sagteware ontwikkel om die dinamiese gedrag te voorspel. 'n Skaalmodel van die prototipe was gebou en in die sleeptenk by Universiteit Stellenbosch getoets en die eksperimentele resultate met die simulasie se resultate vergelyk. 'n Beheer-algoritme is daarna ontwerp, deur middel van die wiskundige model, om die rolhoek en diepte van ontplooiing te beheer.Hierdie algoritme is tydens simulasie getoets. Die resultate het aangedui dat die simulasiemodel akkuraat die gedrag van die prototipe tydens toetse voorspel het, en die resultate het gewys dat die toestel beide stabiel en beheerbaar is. Die gevolgtrekking is gemaak dat die SEO se ontwerpkonsep verdere studie regverdig. Die aanbevelings is dat die eksperimentele model verbeter word om betroubare eksperimentele resultate te verseker, dat verdere kompleksiteit by die simulasiemodel gevoeg word, en dat die beheer-algoritme op die verbeterde model in die sleeptenk getoets word.
87

Análise dos impactos econômicos da implantação de parques eólicos no Estado da Bahia / Analysis of the economic impacts of wind power plant implementa-tion in Bahia State

Melo, Jefferson Lisboa 20 September 2017 (has links)
Submitted by Filipe dos Santos (fsantos@pucsp.br) on 2017-10-04T11:03:51Z No. of bitstreams: 1 Jefferson Lisboa Melo.pdf: 3417543 bytes, checksum: 2263162ffc072452182f6e90daae8f7a (MD5) / Made available in DSpace on 2017-10-04T11:03:51Z (GMT). No. of bitstreams: 1 Jefferson Lisboa Melo.pdf: 3417543 bytes, checksum: 2263162ffc072452182f6e90daae8f7a (MD5) Previous issue date: 2017-09-20 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The objective of this study is analyze the economic impacts of wind power plant imple-mentation in Bahia State, Brazil. Impact indicators are direct and indirect job creation, carbon emission levels, leases and taxes incomes. The study is based on theoretical research about renewable energies, more specifically in wind power and technological innovation in this sector. As research method, this study uses a descriptive approach, and qualitative content analysis of selected public documents. The evaluation of indi-cators presented social and economic benefits due to wind power plant implementation at Bahia State cities, and highlighted an outstanding increase of IFDM (index com-posed by employment, incomes, education, and health rates). Another important result was the legacy to the community, due to educational and cultural projects related to wind power plant development / O objetivo deste trabalho é analisar os impactos econômicos da implantação de par-ques eólicos no Estado da Bahia. Os indicadores de impacto são geração de empre-gos diretos e indiretos, níveis de emissão de carbono, renda gerada pelos arrenda-mentos e o recolhimento de tributos. O trabalho respalda-se em levantamento teórico sobre as energias renováveis e se aprofunda em energia eólica e a inovação tecnoló-gica do setor. Metodologia da pesquisa: descritiva com método qualitativo com análise de conteúdo nos documentos públicos coletados para o estudo. A análise dos indica-dores mostrou a ocorrência de benefícios econômicos e sociais decorrentes da im-plantação dos parques eólicos nos municípios na Bahia, destacando o expressivo au-mento do índice IFDM (composto por indicadores de emprego e renda, educação e saúde). Outro resultado importante, o legado para a comunidade decorrente de proje-tos culturais e educacionais associados à implantação dos parques
88

Assessment of tidal stream energy potential for Marine Corps Recruit Depot Parris Island

Gay, Thomas Joseph 24 August 2010 (has links)
The energy of the tides represents one globally existent source of renewable energy, and has the potential to play a major role in a sustainable future. An assessment of the potential for tidal energy extraction using marine current turbines at a particular location in the Beaufort River near Parris Island, South Carolina is presented. The Marine Corps Recruit Depot located on Parris Island is situated between the confluence of the Broad and Beaufort Rivers. These rivers are tidally dominated, and experience some of the largest tidal ranges in the southeastern United States, between 2.5 and 3 meters during spring tide periods. Because Parris Island already has much of the necessary land-based infrastructure in place, there is logical potential for the extraction of kinetic energy from the nearby tidal streams using underwater turbines for power production. In order to evaluate the potential of a particular location to produce significant amounts of energy using these types of devices, extensive investigations must be conducted to determine important site characteristics such as water depth, current velocity, and water level fluctuations over time. This potential was investigated using in-situ measurements in the vicinity of the pump station on Parris Island, and by developing a numerical model of the region using the Regional Ocean Modeling System (ROMS). This model was calibrated using the results from the in-situ measurements, and was then used to determine the impacts of tidal energy extraction on the local flow field. Results from in-situ measurements indicate that tidal currents along the portion of the Beaufort River analyzed in this study are driven primarily by the semi-diurnal M2 tidal constituent. The tidal range at the study site is approximately 2 meters on average, with a mean depth-averaged current velocity magnitude of 0.57 m/s predicted for a period of one year. A mean depth-averaged current velocity magnitude of 0.59 m/s was observed over the course of the longer-term ADCP deployment from November 12 to December 17, 2009. The maximum current speed at the site is approximately 1.2 m/s at the water surface. The ROMS model applied to the coastal areas surrounding Parris Island, SC produces results that closely resemble in-situ measurements collected previously during both the boat-based survey and the longer-term ADCP deployment. In the analysis of the effects of energy extraction from the system, four separate cases were considered in which 10, 20, 30, and 60% of the total kinetic energy contained in the flow was dissipated near the location of the longer-term ADCP deployment. Minimal impacts on the local hydrodynamics were observed across the four cases considered.
89

Gyvenamųjų namų ekologiškos statybos ateitis Lietuvoje bei ekonominiai aspektai / Future prospects of eco-building of residential houses in Lithuania and economic aspects

Skuminaitė, Aistė 23 July 2008 (has links)
Baigiamojo magistro darbo tikslas - išanalizuoti naujų ekologiškų statybinių medžiagų ir inžinerinės įrangos iš atsinaujinančių energijos išteklių raidą pasaulyje ir jų taikymą individualių gyvenamųj�� namų statyboje, ir pateikti racionaliausius sprendimus, pritaikant juos gyvenamųjų namų statyboje Lietuvoje, atsižvelgiant į ekonominius aspektus. Šiame darbe nagrinėjama gyvenamajai žmogaus aplinkai ir sveikatai kenksmingų veiksnių įtaka, atkreipiant dėmesį į naudojamas statybines medžiagas ir inžinerinę įrangą, statant gyvenamuosius namus, ir pateikiant tradicinėms statybos technologijoms alternatyvų. Apibūdinant „žaliosios energijos“ inžinerinės įrangos ir ekologiškų statybinių medžiagų plėtrą pasaulyje, pateikiamas jų praktinis panaudojimas, statant individualiuosius gyvenamuosius namus. Atsižvelgiant į naujas statybos direktyvas, plėtojant gyvenamųjų namų ekologišką statybą Lietuvoje, šios statybos ekonominius aspektus ir Lietuvos geografines sąlygas, pateikiami labiausiai galimi ekologiškos statybos variantai Lietuvos sąlygomis. Remiantis atliktos apklausos apie gyvenamojo namo ekologišką statybą rezultatais, palyginus projektinio ekologiško gyvenamojo namo ir tradicinio skydinio gyvenamojo namo mechanines savybes ir statybos išlaidas, darbo pabaigoje pateikiamos išvados apie ekologiškos statybos būsto statybos ir rinkos perspektyvas Lietuvoje. Darbo apimtis – 84 p. teksto be priedų, 22 pav., 9 lent., 91 literatūros šaltiniai. Atskirai pridedami darbo priedai. / The objective of final paper of master studies is to analyze the development of new ecological construction materials and engineer systems from renewable energy resources and its implementation in living houses construction industry, giving the most rational solutions to this construction technology implementation in Lithuania, considering the economical aspects. In this paper there are studying the influence of harmful factors to living environment and people health, taking attention to the construction materials and engineer facility that are used in living houses construction, and giving the alternatives to traditional construction technology. Defining the engineer systems of “green energy” and ecological construction materials development in the world, there are giving its practical use in living houses construction. Considering to new construction directives in Lithuania, economical aspects and geographical conditions in Lithuania, there are giving most impossible variants of living houses ecological construction in Lithuania. According to the results of questioning about ecological construction of living houses, after comparison of mechanical features and construction costs of potential ecological house and traditional living house, in the end of the work there are giving conclusion about the perspectives of ecological house construction and its market in Lithuania. Span of final paper – 84 pages of text not including appendix, 22 illustrations, 9 tables, 91 sources... [to full text]
90

Ocean current energy resource assessment for the United States

Yang, Xiufeng 13 January 2014 (has links)
Ocean currents are an attractive source of clean energy due to their inherent reliability, persistence and sustainability. The Gulf Stream system is of particular interest as a potential energy resource to the United States with significant currents and proximity to the large population on the U.S. east coast. To assess the energy potential from ocean currents for the United States, the characterization of ocean currents along the U.S. coastline is performed in this dissertation. A GIS database that maps the ocean current energy resource distribution for the entire U.S. coastline and also provides joint velocity magnitude and direction probability histograms is developed. Having a geographical constraint by Florida and the Bahamas, the Florida Current has the largest ocean current resource which is fairly stable with prevalent seasonal variability in the upper layer of the water column (~200m). The core of the Florida Current features higher stability than the edges as a result of the meandering and seasonal broadening of the current flow. The variability of the Gulf Stream significantly increases as it flows past the Cape Hatteras. The theoretical energy balance in the Gulf Stream system is examined using the two-dimensional ocean circulation equations based on the assumptions of the Stommel model for quasi-geostrophic subtropical gyres. Additional turbine drag is formulated and incorporated in the model to represent power extraction by turbines. Parameters in the model are calibrated against ocean observational data such that the model can reproduce the volume and kinetic energy fluxes in the Gulf Stream. The results show that considering extraction over a region comprised of the entire Florida Current portion of the Gulf Stream system, the theoretical upper bound of averaged power dissipation is around 5.1 GW, or 45 TWh/yr. If the extraction area comprises the entire portion of the Gulf Stream within 200 miles of the U.S. coastline, the theoretical upper bound of averaged power dissipation becomes approximately 18.6 GW or 163 TWh/yr. The impact of the power extraction is primarily constrained in the vicinity of the turbine region, and includes a significant reduction of flow strength and water level drop in the power extraction site. The turbines also significantly reduce residual energy fluxes in the flow, and cause redirection of the Gulf Stream. A full numerical simulation of the ocean circulation in the Atlantic Ocean is performed using Hybrid Coordinate Ocean Model (HYCOM) and power extraction from the Florida Current is modeled as additional momentum sink. Effects of power extraction are shown to include flow rerouting from the Florida Strait channel to the east side of the Bahamas. Flow redirection is stronger during peak summer flow resulting in less seasonal variability in both power extraction and residual fluxes in the Florida Current. A significant water level drop is shown at the power extraction site, and so is a slight water level rise along the coasts of Florida and the Gulf. The sum of extracted power and the residual energy flux in the Florida Current is lower than the original energy flux in the baseline case, indicating a net loss of energy reserve in the Florida Current channel due to flow redirection. The impact from power extraction on the mean flow field is concentrated in the near field of the power extraction site, while shifts in the far flow field in time and space have little impact on the overall flow statistics.

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