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Abbey, Chad. "A doubly-fed induction generator and energy storage system for wind power applications /". Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=81522.
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Wind generation has become the most important alternate energy source and has experienced increased growth in Europe during the past decade while more recently, the same trends have been exhibited in North America. Although it has great potential as an alternative to less environmentally friendly energy sources, there are various technical challenges that cause wind to be regarded negatively by many utilities. Others are hesitant to accept its widespread implementation, particularly when the penetration of wind in a given area is high.This work presents the addition of an energy storage system to a wind turbine design.
Various advantages are exhibited for the wind turbine with energy storage. Firstly, the generator is capable of accurately controlling the output power of the generator and inevitably of the wind park. Reactive power requirements are also reduced as a result of a more stable voltage at the point of interconnection. In addition, improved transient performance is exhibited for various local disturbances.
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Radebe, Thandwefika. "Are solar home systems a more financially viable method of electrifying Ghana households?" Master's thesis, Faculty of Commerce, 2021. http://hdl.handle.net/11427/33001.
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Africa still has the lowest electrification rates in the world with over 600 million people estimated to be living without access to electricity. What makes the challenge even greater for Africa is that the continent is so sparsely populated that building grid infrastructure is not viable in many cases. However, “pay-as-you-go” solar home systems have provided the continent with the opportunity to correct its electrification deficit. These innovations are not new and many of the costs of operating these systems have reached grid parity when one considers the Levelized Cost of Energy Model. However, these projects still fail to meet institutional investors' bankability criteria. The aim of this study is to try and understand whether solar home systems provide the investor with an opportunity to make a larger risk-adjusted return versus existing grid-based power station projects being considered on the continent. This study uses Ghana's recently built Kpone power station as a case study to complete this analysis. The study also seeks to assess what viability criteria is employed by a broad base of investors if they were to consider funding off-grid power. The study makes use of the Net Present Value model to compare the returns for Kpone and Zola Electric's Infinity solar home system. The study also conducts inductive qualitative analysis to try and ascertain what criteria is assessed for project viability and then builds a conceptual framework for assessing future projects. The study found that Kpone provided a better risk-adjusted return to that of Zola Electric's solar home system, largely because of Kpone's project finance structure reducing the risk of the investment. Our findings also show that investment ticket size, company track record and management track record are among the most highly considered criteria for investments into off-grid companies.
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Pimperton, M. G. "The meatgrinder : an efficient current-multiplying inductive energy storage and transfer circuit". Thesis, Loughborough University, 1990. https://dspace.lboro.ac.uk/2134/10828.
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The meatgrinder is a high-efficiency inductive energy storage and transfer circuit which may be used to supply high-current pulsed power requirements in applications such as electromagnetic propulsion. It overcomes the inherent 25% efficiency limit when transferring energy between uncoupled inductors and simultaneously provides current multiplication. An unloaded six-step demonstration circuit has been used to multiply current from 7A to 76A at an efficiency of 44%, and a single-step demonstration circuit has been used to multiply the current in an uncoupled load induct or from lOA to 30A, the efficiency of energy transfer being 31%. Both circuits use power MOSFETs for switching. These circuits have been used in conjunction with theoretical analysis and computer simulation to study the design and performance of the meatgrinder. Investigations have been carried out in order to confirm the basic theory, to clarify the details of circuit operation, and to provide the information necessary for future feasibility studies.
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Navas, Michael Andrés Hernández. "Sistema de armazenamento aplicado a sistemas eólicos empregando conversores de fonte z conectados à rede elétrica". reponame:Repositório Institucional da UFABC, 2015.
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Orientador: Dr. Alfeu J. Sguarezi FilhoDissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Engenharia Elétrica, 2015.
Neste trabalho apresenta-se uma configuração do sistema de armazenamento de energia com baterias aplicado a sistemas de geração de energia eólica empregando conversores de fonte Z conectados à rede elétrica. Os geradores de indução gaiola de esquilo, são frequentemente utilizados nos sistemas de geração de energia eólica, por sua robustez, simplicidade, peso menor e custo baixo. Este é conectado diretamente ao conversor de potência bidirecional back to back, pode fornecer potências ativa e reativa à rede elétrica. Além disso, é estudado o conversor de fonte Z aplicado nesta topologia. No entanto, a implantação de sistemas de armazenamento de energia com baterias nos sistemas de geração de energia eólica na atualidade é muito importante, devido à possibilidade de oscilações da tensão e corrente na rede elétrica, portanto, estes podem ajudar à estabilização das tensões, correntes e a frequência na rede elétrica. Este sistema é conectado ao conversor back to back por meio de um conversor elevador-abaixador de corrente contínua. Para controlar a velocidade no eixo do rotor no gerador de indução, a estratégia é baseada no controle direto de torque. Enquanto, para o conversor do lado da rede é empregada a técnica de controle orientado pela tensão. Para o banco de baterias é utilizado o controle da tensão no barramento de corrente contínua e do fluxo na corrente da bateria, utilizando controladores do tipo PI. Com os novos desenvolvimentos tecnológicos nas chaves de potência, são apresentadas topologias de conversores CC-CA como o conversor de fonte Z, este tipo de conversor corrige algumas limitações do conversor back to back, com as características de elevador/abaixador de tensão, sem o uso de dispositivos de comutação, são permitidos os curto-circuitos na chaves, empregando novas técnicas de modulação, e reduz a quantidade harmônica injetada na rede elétrica. Os estudos foram realizados por meio de técnicas de simulação computacional usando modelos matemáticos do sistema estudado para a validação das estratégias de controle empregadas em diferentes condições de operação. Para as simulações empregou-se a ferramenta computacional SimPowerSystems R do Matlab/Simulink R .
This paper presents a battery energy storage system applied to wind power generation based on Z-source inverter connected to the power grid. The squirrel cage induction generators, often used in wind power generation systems, for its robustness, simplicity, lower weight and low cost. This is connected directly to the bidirectional power converter back to back, therefore, and provides active and reactive powers to grid. In addition, it is studied the Z-source inverter applied in this topology. However, the implementation of battery energy storage systems in wind power generation systems, currently is very important, due to possibility of the voltage and current fluctuations in the power grid, so these may to stabilisation of current, voltage and frequency on the grid. This system is connected to back to back converter through a DC-DC converter (buck-boost). For the rotor speed control on induction generator, the strategy is based on direct torque control. While, for the grid side converter is employed the technique of voltage oriented control. For the battery bank voltage control is used on DC-link voltage and battery current flow, through PI type controllers. With the new technological developments in the keys of power, DC converters topologies are presented as the Z-source inverter, this type converter fixes some limitations of the converter back to back, with the characteristics of buck-boost voltage, without the use of switching devices, allowed short-circuits on converter, using new modulation techniques, and reduces the amount injected harmonic to power grid. The studies were performed by means of computer simulation techniques using mathematical models of studied system to validate the control strategies employed in different operating conditions. For the simulations was used the computational tool SimPowerSystems R do Matlab/Simulink R .
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Tahat, M. A. "Thermo-chemical energy storage system". Thesis, Cranfield University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260146.
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Chang, Xiao. "Supercapacitor based energy storage system". Thesis, University of Strathclyde, 2013. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=25509.
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The supercapacitor, as a recently developed electrochemical energy storage device, offers extremely high capacitance per unit volume. Due to its unique double-layer structure and electrostatic charge mechanism, the supercapacitor has a much higher power density than the battery, and a much higher energy density than the conventional capacitor. It also benefits from a long cycle life, and wide temperature range. However, limited by a low cell voltage of 2.7V and high equivalent series resistance, the supercapacitor may be inefficient for high power grid level applications. Characteristic analysis of the supercapacitor shows that the efficiency reduces to 54.7% at peak current conditions. Based on supercapacitor modelling studies, two parameter identification methods are proposed, which are realised by a simple experiment, with an acceptable accuracy. A parallel combined supercapacitor and electrolytic capacitor energy storage system is proposed to improve high power application performance, which offers efficiency improvements in excess of 10%. A detailed description of such parallel capacitor systems are included in this thesis, where a design guide is developed to achieve an optimal design in terms of system efficiency, power capability, and volume. The capacitor based energy storage technique is suited to distributed generation applications where low-voltage ride through and grid code compliance are important considerations. A supercapacitor based static synchronous compensator is proposed, which is able to manipulate both active and reactive power exchange with the power system. Steady-state and transient responses are studied based on simulation of a test power system. A system frequency based control algorithm is used for active power control, which has a better stabilised system frequency than with conventional voltage control. The parallel hybrid capacitor technique is employed, which greatly improves the system performance in terms of efficiency, thermally, costs, and volume, compared with a system that only uses supercapacitors.
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Ranjith, Adam. "Thermal Energy Storage System Construction". Thesis, KTH, Skolan för industriell teknik och management (ITM), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-264530.
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In the framework of 2020 PUPM HEAT project three different types of thermal energy storage (TES) systems are being constructed and analyzed at a demonstration site set up at the power plant IREN in Moncalieri, Italy. KTH will assist this project by setting up a validation rig where three TES systems in smaller dimensions will be constructed and analyzed for its performance, to use as guideline for the demonstration site rig. The first TES system that is being constructed is the submerged parallel spiral heat exchanger which is a completely new version of latent heat storage to be tested. For this idea, parallel layers of spiral copper coils will fill up a tank shell which in turn will be filled with phase change material. By injecting high temperature heat transfer fluid, phase change material will change its state and energy will be stored in the system. When injecting low temperature heat transfer fluid, the energy will be extracted. This BSc thesis will present detailed design solutions for the tank shell and the spiral copper coils that will be used for the heat exchanger. Presented solutions are then used to order parts needed to initiate the construction phase.Inom ramverket för 2020 PUPM HEAT projektet kommer tre olika typer av värmeenergilagrings enheter tillverkas och analyseras vid energikraftverket IREN i Moncalieri, Italien. KTH kommer att assistera detta projekt genom att sätta upp en anläggning med tre liknande värmeenergilagrings enheter i mindre dimensioner som kommer konstrueras och analyseras. Dess data kommer sedan användas som riktlinje för att tillverka de större värmeenergilagringsenheterna i IREN. Den första enheten som tillverkas är en värmeväxlare som bygger på en ny version av latent energilagring. Den kommer att bestå av parallella lager av spiral formade koppar rör som fyller en tank. Tomrummet som blir över kommer att fyllas upp av fasändrings material (PCM). Genom att injicera varmt vatten i systemet kommer PCM:et att byta fas, vilket resulterar i att värmeenergin lagras i systemet. När sedan kallt vatten injiceras kan den sparade energin bli utvunnen. Den här rapporten kommer att presentera designen till tank kåpan såväl som den inre strukturen med kopparrör som behövs till värmeväxlaren. Resultatet ska möjliggöra beställning av alla delar som behövs för att konstruera värmeväxlaren.
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Degnon, Mawuena. "Étude des commutateurs semi-conducteurs à ouverture destinés à des applications de puissance pulsée avec des tensions de sortie allant jusqu'à 500 kV". Electronic Thesis or Diss., Pau, 2024. https://theses.hal.science/tel-04685830.
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Dans les systèmes de hautes puissances pulsées, le stockage inductif présente un avantage indéniable vis-à-vis du stockage capacitif du fait de sa plus forte densité d’énergie. L’exploitation de cet avantage nécessite toutefois l'utilisation d'un interrupteur à ouverture pour générer l'impulsion de tension. En outre, compte tenu de la demande croissante de générateurs impulsionnels fiables, en particulier pour les applications industrielles, il devient indispensable de recourir aux composants semi-conducteurs. La diode SOS (Semiconductor Opening Switch), développée dans les années 1990 à l'Institute of Electrophysics en Russie, est un candidat idéal pour la commutation état solide à ouverture, de par sa capacité à générer des impulsions de haute puissance de manière fiable et répétitive, tout en offrant une longue durée de vie et un fonctionnement exempt de maintenance. Cependant, le manque de fabricants de diodes SOS limite leur utilisation à grande échelle. Par conséquent, cette thèse se concentre sur l’étude de diodes disponibles dans le commerce (OTS : Off-The-Shelf) capables de commuter rapidement des courants élevés et de générer des tensions nanosecondes pouvant atteindre 500 kV. Plusieurs types de diodes, incluant les diodes de redressement, à avalanche, à temps de récupération rapide et de suppression de tension transitoire (TVS) ont été étudiés en tant qu’interrupteurs à ouverture, en comparaison avec les diodes SOS de référence. Pour mener à bien cette étude, des bancs d’essai à basse, moyenne et haute énergie (respectivement 25 mJ, 10 J et 40 J) ont été mis au point. Afin d’augmenter leur efficacité énergétique, ces bancs utilisent un circuit basé sur un élément magnétique unique : un transformateur impulsionnel saturable. Plusieurs noyaux magnétiques nanocristallins ont été examinés sur le banc de 10 J dans le but d’optimiser les performances du transformateur. Parmi les diodes étudiées sur les bancs de 25 mJ et 10 J, les diodes TVS et les diodes de redressement ont émergé du lot, démontrant des performances de temps de commutation de l'ordre de la nanoseconde et de tensions générées de plusieurs kilovolts. Enfin, un prototype de générateur de hautes puissances pulsées de 40 J (GO-SSOS) basé sur un interrupteur OTS composé de diodes de redressement a été développé. Le rendement énergétique du système varie de 35% à 70% selon la valeur de la charge, et la puissance crête obtenue est supérieure à 300 MW. Sur une charge de 1 kΩ, l'impulsion de tension générée atteint une amplitude de 500 kV avec un temps de montée de 36 ns et une largeur à mi-hauteur de 80 ns. La reproductibilité des impulsions à une fréquence de répétition de 60 Hz est démontrée, ainsi qu’une application de génération de décharges couronnes. Les travaux prouvent la fiabilité des diodes OTS en mode SOS, ne révélant aucune dégradation après quelques milliers d'impulsions générées. Ils ouvrent également la voie à l’utilisation de cette technologie pour des applications industrielles telles que la stérilisation par faisceau d’électronsIn pulsed power systems, inductive energy storage has an advantage over capacitive storage because of its higher energy density. Exploiting this advantage requires the use of an opening switch to generate the voltage pulse. Moreover, the growing need for reliable pulsed power generators, particularly for industrial applications, strongly supports the adoption of solid-state solutions. The Semiconductor Opening Switch (SOS) diode developed in the 1990s at the Institute of Electrophysics in Russia is an ideal candidate for solid-state opening switching because of its ability to reliably generate high-power pulses at high repetition rates while offering long lifetime and maintenance-free operation. However, the lack of SOS diode manufacturers prevents their widespread use. This thesis is therefore devoted to the study of off-the-shelf (OTS) diodes capable of rapidly switching high currents and generating nanosecond voltages of up to 500 kV. The research includes the investigation of various diode types including rectifier, avalanche, fast recovery, and transient voltage suppression (TVS) diodes as opening switches in comparison with state-of-the-art SOS diodes. Low, medium, and high-energy (25 mJ, 10 J, and 40 J respectively) test benches are developed for the experiments. Their circuits use a single magnetic element – a saturable pulse transformer – resulting in high energy efficiency. Several nanocrystalline cores are examined for optimum transformer performance at an energy of 10 J. Among the diodes investigated at 25 mJ and 10 J energy, the TVS and rectifying diodes stand out particularly promising with nanosecond switching time and generated voltages in the kilovolt range. Finally, a 40 J pulsed power generator prototype (GO-SSOS) based on an OTS opening switch consisting of rectifier diodes is developed. The GO-SSOS achieves a peak power of more than 300 MW with an energy efficiency ranging from 35% to 70% depending on the load value. Across a 1 kΩ load, the voltage pulse generated reaches 500 kV amplitude with a rise time of 36 ns and a pulse width of 80 ns. The system shows high reproducibility at a repetition rate of 60 Hz and is used to demonstrate a corona discharge application. The work proves the reliability of the OTS diodes in SOS mode, revealing no degradation after thousands of pulses. It also offers the prospect of using this technology in industrial applications such as electron-beam sterilization
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Thaicham, Pruitipong. "Fluidised-MCPCM glazed energy storage system". Thesis, University of Nottingham, 2004. http://eprints.nottingham.ac.uk/11057/.
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The thesis presents an experimental investigation into the feasibility of using a slurry containing a micro encapsulated phase change material (MCPCM), n-eicosane, as a heat transfer fluid for enhanced latent heat transport. Increasing the convective heat transfer coefficient would permit the use of a smaller volumetric flow rate and reduce pumping power. The primary parameters investigated are the volumetric concentrations and flow rates. Measurements of thermal capacity of the novel slurries were performed using two techniques, standard differential scanning calorimeter (DSC) and thermal analysis (TA). Pumping power consumption, viscosity and pressure loss of the flowing slurries were investigated in order to determine the most suitable concentration of MCPCM used in the slurry, over the range 5-40%. The effects of repeated use of liquid-solid phase change particles upon melting and solidifying were studied using a small-scale rig of a closed loop circuit. The research work further involved the design, construction and tests the proposed system based on incorporating microencapsulated phase change material (MCPCM) within a fluidised and sealed double glazed panel, which could be integrated into building fabric. The use of a MCPCM slurry can improve the performance of a working fluid by as much as 52% compared to a single phase fluid. A concentration of 20-30% was the most suitable mixture for the working fluid due to the associated heat capacity and reasonable pressure drop. Measurement showed that a saving in pumping power of 12% could be obtained. The performance of the fluidised glazed energy storage system can be improved by up to 18% with the use of MCPCM slurry as a working fluid.
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Abbey, Chad Michel. "Energy storage system optimization and control with wind energy". Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66694.
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This thesis proposes a methodology for planning, scheduling and on-line control of an energy storage system for the integration of wind energy. Using the case study of a remote wind-diesel system, the different time frames of the design and implementation process are detailed. First, a long-term planning approach for rating of the power and energy capacities of the ESS is presented, based on stochastic optimization. The formulation is then adapted into a hourly scheduling approach and results are compared with the expected cost of energy and energy requirements resulting from the planning study. The optimization results are used as training data for an artificial neural network, in an effort to generate an on-line control that captures inherent rules, using artificial intelligence. The ESS is realized as a two-level ESS and a general control structure for on-line operation of multi-level ESS is proposed and adapted for the wind-diesel system, as the first level in a hierarchical control. The system is evaluated in simulation and selected results are validated using a hardware-in-the-loop representation of the system, demonstrating that the proposed controller is realizable.Cette thèse propose une méthodologie pour la planification, l'utilisation et la commande d'un système de stockage d'énergie permettant l'intégration de l'énergie éolienne. Utilisant comme étude de cas un réseau autonome alimenté par un système éolien-diesel, les différentes étapes de la conception et la mise en oeuvre sont détaillées. Premièrement, une étude de planification à long terme pour le dimensionnement de la puissance nominale et de la capacité énergétique du stockage est présentée, basée sur les méthodes d'optimisation stochastique. La formulation est ensuite adaptée à une commande sur une base horaire et les résultats sont comparés, au niveau de l'énergie et de la quantité d'énergie utilisée, aux résultats obtenus dans l'étude de planification. Les résultats obtenus par optimisation du système sont utilisés dans l'entrainement d'un réseau de neurones artificiels, afin de produire une commande qui capte les règles inhérentes au système, utilisant l'intelligence artificielle. Le stockage d'énergie est réalisé par un système de stockage à deux niveaux et une structure de commande appropriée à plusieurs niveaux est proposée et adaptée pour un système éolien-diesel, comme premier niveau d'une commande hiérarchique. La performance du système est évaluée par simulation et certains résultats ont été validés avec un banc d'essai. Celui-ci consiste à des convertisseurs électroniques intégrés avec une représentation par simulation temps réel du système. Les résultats obtenus concordent avec les résultats de simulation et confirment que la commande proposée est réalisable.
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Rosen, Josefin, e Frida Nilsson. "Decentralized Polygeneration Energy System : Energy Storage Requirements & Challenges". Thesis, KTH, Energiteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-190834.
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Due to the recent development of small-scale energy technologies, the energy industry is changing from a centralized to a more decentralized energy system. And because of the current problems with limited energy sources it is now important to focus on renewable energy sources and how to store the energy for later use. One solution is polygeneration system. A Polygeneration energy system is a system that combines heat, cold and power generation. Therefor it is a flexible system that can easily be modified depending on the size of the system, its application, the demands and other requirements. This project focuses on mapping different types of energy storage and the important parameters in each method. Initially the different concepts of energy storing will be described thoroughly so the reader gets an overview of the different storing methods. Thereafter the report maps the different methods and how developed they are via TRL (Technology Readiness Level). To achieve a greater knowledge of how a polygeneration systems is built and optimized, , an optimization tool can be used. One of these programs is HOMER. HOMER will be used in this project to create a wider comprehension about optimization and effects of energy storage in a polygeneration system. By using different data, the program can calculate the profit, from an economic and a geographical perspective. The demarcation has been selected by choosing a geographical area and what sorts of resources that are available in relation to it. Since the main purpose with the report consists of defining ways to store energy, the focus will be on the different battery types that exist today. A comparison between three different types of batteries will be done and further on what results they will show. The optimization in HOMER showed that it is possible to build a decentralized polygeneration system on the chosen location, Sagar Island. The system combines different renewable energy resources such as, solar and wind together with a generator, converter and batteries to create a sustainable system. The results showed a high investment cost for the energy system in all cases, despite the use of different battery types. However, the investment is profitable for the population on Sagar Island to have access to electricity and what future benefits that may provide.På grund av den senaste utveckling av småskaliga energisystem, där energiindustrin går från ett centrerat till ett mer decentraliserat system och bristerna som finns i samband med energikällor, är därför nu viktigt att fokusera på förnybara energikällor och hur denna energi kan lagras. En lösning till detta är polygenerationsystem. Ett polygenerationsystem bygger på ett system som kombinerar värme, kylning och effektutveckling. Därigenom är det ett flexibelt system som kan modifieras beroende på systemets storlek, efterfrågan och krav. Denna rapport fokuserar på att kartlägga olika typer av energilagring och deras viktiga parametrar. Inledningsvis beskrivs de olika energilagringskoncepten grundligt sådan att läsaren får en överblick av de olika lagringsmetoderna. Därefter kartlägger rapporten de olika metoderna samt hur utvecklade de är genom TRL (Technology Readiness Level). För att få en bättre översikt över hur ett polygenerationsystem är uppbyggt samt dess funktion kan ett optimeringsprogram användas. Ett av dessa program är HOMER. HOMER kommer att användas i denna undersökning för att skapa en bredare förståelse över hur man kan optimera ett polygenerationsystem. Med hjälp av olika indata kan programmet räkna ut systemets vinst, bland annat utifrån ett ekonomiskt samt geografiskt perspektiv. Avgränsningen har valts genom att välja ett geografiskt område samt vilka resurser som finns tillgängliga i anknytning till detta. Eftersom huvudsyftet med rapporten handlar om de olika lagringsmetoderna kommer fokus främst ligga på batterierna, där en jämförelse mellan tre olika batterityper görs och vilka resultat de medför. Optimeringen i HOMER visade att det är möjligt att konstruera ett decentraliserat polygeneration system på den valda platsen, Sagar Island. Systemet kombinerar olika förnybara energikällor så som, sol och vind tillsammans med en generator, omvandlare och batterier för att skapa ett hållbart system. Resultatet visade en hög investeringskostnad för energisystemet i alla fallen, trots användandet av olika batterityper. Emellertid är investeringen lönsam för populationen på Sagar Island att få tillgång till elektricitet och de framtida fördelar som det kan medföra.
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Rydberg, Lova. "RTDS modelling of battery energy storage system". Thesis, Uppsala universitet, Elektricitetslära, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-155960.
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This thesis describes the development of a simplified model of a battery energy storage. The battery energy storage is part of the ABB energy storage system DynaPeaQ®. The model has been built to be run in RTDS, a real time digital simulator. Batteries can be represented by equivalent electric circuits, built up of e.g voltage sources and resistances. The magnitude of the components in an equivalent circuit varies with a number of parameters, e.g. state of charge of the battery and current flow through the battery. In order to get a model of how the resistive behaviour of the batteries is influenced by various parameters, a number of simulations have been run on a Matlab/Simulink model provided by the battery manufacturer. This model is implemented as a black box with certain inputs and outputs, and simulates the battery behaviour. From the simulation results a set of equations have been derived, which approximately give the battery resistance under different operational conditions. The equations have been integrated in the RTDS model, together with a number of controls to calculate e.g. state of charge of the batteries and battery temperature. Results from the RTDS model have been compared with results from the Simulink model. The results coincide reasonably well for the conditions tested. However, further testing is needed to ensure that the RTDS model produces results similar enough to the ones from the Simulink model, over the entire operational range.
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Mueller, Joshua M. (Joshua Michael) 1982. "Increasing renewable energy system value through storage". Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/98540.
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Thesis: S.M. in Technology and Policy, Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program, 2015.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 135-143).
Intermittent renewable energy sources do not always provide power at times of greatest electricity demand or highest prices. To do so reliably, energy storage is likely required. However, no single energy storage technology is dominant when comparing cost intensities of the energy capacity and power capacity of storage. Past research on energy storage technologies has debated the value of storage technologies for different applications, and has compared the cost structures of different storage technologies without finding generalizable results across both locations and technologies. Here, a single performance metric, the benefit / cost ratio (X) of storage value added is analyzed across six locations globally to show that the relative value of storage technologies is largely location invariant. Electricity price dynamics, specifically the frequency and height of price spikes determine the value of storage, while the duration of price spikes determines the relative value of one technology versus another. We find that cost targets can be set for different technologies with ranging energy and power costs of storage.
by Joshua Michael Mueller.
S.M. in Technology and Policy
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Maskey, Anuj. "Battery energy storage system control algorithm design". Thesis, Maskey, Anuj (2019) Battery energy storage system control algorithm design. Honours thesis, Murdoch University, 2019. https://researchrepository.murdoch.edu.au/id/eprint/52653/.
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Microgrid is based on smaller decentralised low voltage system with the use of modern power technology puts different types of Distributed Energy sources solar power, wind power, and energy storage devices together, improving the electrical supply reliability, reducing the feeder loss and ensures the stability of the voltage. The current trend of incorporating energy storage devices in the microgrid is aimed to mitigate the power imbalance and improve the electrical supply reliability. The thesis uses Kalbarri, Western Australia as a case study site with an aim to investigate the appropriate battery technology and formulate control algorithm for the microgrid.
The thesis starts by examining the Australian electrical market including the: socio‐economic, political, and regulatory environment and presents the rationale of having an Energy Storage System in rural Australia. The thesis investigates the various available BESS battery technology options and suggests the most appropriate options for the BESS comprised Kalbarri microgrid model. The MATLAB/Simulink BESS control algorithm design model is presented with an aim to test voltage and frequency regulation under different load condition, including the process of seamless transition from the grid‐connected operation to a grid‐disconnected operation of the microgrid.
The research presents a theoretical control model based on the Power Control theory and existing academic literature on the topic. The thesis examines the control algorithm design to regulate the frequency and voltage using the BESS system to connect to the main three phase AC grid. The overall site model includes a power conversion of two DC sources: BESS and PV system. The BESS control algorithm model comprises of a Power Conversion system that use three‐phase full bridge Insulated Gate Bipolar Transistors (IGBTs) with LCL filter and a Power Control System based on Phased Lock Loop to synchronise with the grid frequency. The Power Control system uses a three‐phase sinusoidal abc frame conversion to a DC reference signal dq0 frame to incorporate PI controller with an aim that the intermittence of the renewable energy generation Wind and PV system can be maintained to a balanced state in the grid within a short frame of time. The BESS control algorithm model uses a Current Controlled Voltage Source Converter for its simple controller design, better performance during grid fault and the overall cost saving of the system. The thesis simulation utilized CCVSC for its tight regulation of the line current, mainly VSC protection against overcurrent and a high accuracy instantaneous current control.
However, the author acknowledges the simulation result indicate an anomaly with voltage control while using CCVSC in the control algorithm model in power source transition test condition. Hence, as a part of future improvement with a focus on the overcurrent, the author concludes possible testing with the VCVSC based control algorithm model for rapid and continuous response for smooth dynamic control and automated P and Q power control in both steady‐state and dynamic system conditions.
Finally, the impact on the microgrid is presented with an in‐depth analysis of the results, including the achievements, innovations, challenges and the suggestion for future improvement in the discussion section of the report.
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Li, Jianwei. "Design and assessment of the superconducting magnetic energy storage and the battery hybrid energy storage system". Thesis, University of Bath, 2017. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.760945.
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Svensson, Henrik. "Pre-Study for a Battery Storage for a Kinetic Energy Storage System". Thesis, Uppsala universitet, Elektricitetslära, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-249173.
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This bachelor thesis investigates what kind of battery system that is suitable for an electric driveline equipped with a mechanical fly wheel, focusing on a battery with high specific energy capacity. Basic battery theory such as the principle of an electrochemical cell, limitations and C-rate is explained as well as the different major battery systems that are available. Primary and secondary cells are discussed, including the major secondary chemistries such as lead acid, nickel cadmium (NiCd), nickel metal hydride (NiMH) and lithium ion (Li-ion). The different types of Li-ion chemistries are investigated, explained and compared against each other as well as other battery technologies. The need for more complex protection circuitry for Li-ion batteries is included in the comparison. Request for quotations are made to battery system manufacturers and evaluated. The result of the research is that the Li-ion NMC energy cell is the best alternative, even if the cost per cell is the most expensive compared to other major technologies. Due to the budget, the LiFeMnPO4 chemistry is used in the realisation of the final system, which is scaled down with consideration to the power requirement.
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Ross, Michael. "Energy storage system scheduling in wind-diesel microgrids". Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=95237.
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This thesis proposes a knowledge based expert system tool that can be used as an on- line controller for the charging/discharging of an energy storage system in a wind-diesel microgrid. The wind-diesel microgrid is modelled, and a typical energy storage system is implemented to test the functionality of the controller using hourly-discrete power val- ues. The results are compared against an offline optimization that was provided 24-hour lookahead wind values, as well as a controller that was implemented using artificial neural networks. The knowledge based expert system is then used to analyze the cost of energy, by means of a parametric analysis, consisting of varying the wind penetration, energy stor- age system power rating and energy rating to determine for which wind penetration values a storage system implementation would be technically and economically viable. Differ- ent storage technologies are tested in a one-year time frame to determine which would be best suited for this particular application. The energy storage systems are implemented as single-layer and dual-layer, in which the knowledge based expert system is modified for the latter analysis, in order to determine whether or not there are advantages to having a dual-layer storage system. Throughout these analyses, the flexibility of the knowledge based expert system controller to various energy storage systems and microgrid models is verified. It also demonstrates that, in a context of high base generation costs, energy storage can be a viable solution to managing wind power variations.Cette thèse propose un système expert avec une base de connaissance qui peut être utilisé comme un contrôleur lors de la charge et de la décharge d'un système de stockage d'énergie dans un micro-réseau éolien-diesel. Un micro-réseau éolien-diesel modèle est établi, et un stockage est installé pour tester les fonctionnalités du contrôleur en utilisant des valeurs de la puissance horaire. Les résultats sont comparés avec une optimisation utilisant 24 heures de valeurs en avance pour la vitesse du vent, et aussi avec un contrôleur basé sur un réseau de neurones artificiels. Le contrôleur système expert est ensuite utilisé pour analyser les coûts d'énergie d'une analyse paramétrique, en variant la pénétration du vent, la puissance nominale du stockage, et la capacité nominale du stockage. Cette analyse indique pour quelles valeurs de pénétration éolienne une mise en vre d'un stockage serait viable économiquement et techniquement. Différentes technologies de stockage sont testées afin de déterminer laquelle serait le mieux adapté pour cette application particulière. Les systèmes de stockage sont réalisés à l'aide d'un ou de plusieurs types de systèmes, et le contrôleur système expert est modifié en conséquence, afin de déterminer s'il y a des avantages à avoir ce type de stockage. Ces analyses montrent aussi que le contrôleur système expert a la capacité et la flexibilité de s'adapter à des technologies ainsi qu'à des micro-réseaux de différents types.
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Alhuttaitawi, Saif. "Storage System for Harvested Energy in IoT Sensors". Thesis, Högskolan Kristianstad, Fakulteten för naturvetenskap, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:hkr:diva-18291.
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This work presents an energy system design for wireless sensor networks (WSNs) after applying our design the WSN should theoretically have an infinite lifetime. Energy harvesting sources can provide suitable energy for WSN nodes and reduce their dependence on battery. In this project, an efficient energy harvesting and storage system is proposed. By using (two supercapacitors and four DC/DC converters with step up /step down capabilities) all of them controlled by Microcontroller via switches to consider the best way to save energy to keep the WSN alive as long as possible. The usage of supercapacitors as an energy buffer to supply the sensor components (microcontroller and radio) with energy it needs to work. We could control the energy flow according to a specific voltage levels in supercapacitors to guaranty the full functionality for WSN with minimizing the loss of energy, and that’s leads to long time life for the wireless sensor node WSN. Another important thing we find in our experiment that is the inner leakage of the supercapacitor and how it has a critical effect on how long it can serve our system with energy. This paper contains on two theoretical sections (Part one and part two) which are based on literature reviews, and one experimental section (Part three) based on experimental building the prototype, coding and testing.
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Maurel, Marion. "Performance Testing of a MobileThermal Energy Storage System". Thesis, KTH, Energiteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-232325.
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I Europa utgör industrisektorn 31% av den globala efterfrågan på energi och bland detta går 20 till 50% avden totala energiinmatningen förlorad när värme släpps ut i atmosfären. Samtidigt beskriver the”European Commission Energy Roadmap 2050” vilken viktig roll energilagring i processen för utfasningav fossila bränslen i det europeiska energisystemet har.I linje med dessa observationer testar och utvecklar energiavdelningen vid Kungliga Tekniska Högskolan(KTH) ett projekt med titeln Heat on Wheels. Grundprincipen för detta projekt är att samla spillvärme inomindustrin och frakta den till användare - t.ex. via ett fjärrvärmenät – med hjälpa av ett fasväxlingsmaterial(PCM) som en mellanprodukt för att lagra energi och sedan ta den från en punkt till en annan i en mobiltermisk energilagringsenhet (M-TES).Denna avhandling tar del i att testa utförandet av Erytritol som PCM-lagring och frigöra energi i enprototyp på KTH. Prototypen består av en tubvärmeväxlare nedsänkt i PCM. HTF:en antingen smälterPCM:t (endoterm process) eller fryser det (exoterm process). M-TES lagringskapacitet är ca 178 kWh/m3.Resultaten visar en 2,50 gånger längre laddningstid och en 1,62 gånger längre urladdningstid med etthalverat HTF-flöde. Att halvera HTF-flödet leder också till en 50% minskning av effekten i PCM överhela laddningsprocessen. Kraften mottagen av HTF:en under hela processen halveras då urladdnings-HTF-temperaturen ökar med 33%. Smält/frysprocessen av PCM är beroende av lokaliseringen ilagringsenheten. Icke desto mindre förefaller Erytritol av teknisk kvalitet kunna upprätthålla upprepadeuppvärmnings-och kylnings-cykler, utan märkbart försämrad lagring.Studien visade också att med den föreslagna utformningen skulle uppskalning M-TES med en 700%ökning i längd resultera i en total värmeöverföringskoefficient multiplicerad med 7, vilket därmedsäkerställer en ännu snabbare process laddning/urladdning.En rekommendation för framtida arbete är att undersöka hur man kan homogenisera smältning/frysningav PCM i värmeväxlaren, kanske genom att bättre sprida HTF-flödet mellan rören. Det skulle också varafördelaktigt att arbeta med att minska förlusterna i mellan laddningen och urladdningen för att behålla såmycket energi som möjligt. Ytterligare studier om effekterna av uppskalning av laboratorieprototypen kanockså utföras, med hänsyn till olika konstruktioner såsom en större rördiameter till exempel.In Europe, the industry sector constitutes 31 % of the global energy demand and among this, 20 to 50 %of the total energy input is lost as heat released to the atmosphere. In the meantime, the EuropeanCommission Energy Roadmap 2050 recognizes the essential role of energy storage in the process ofdecarbonisation of the European energy system.In line with these observations, the Energy Department of the Royal Institute of Technology (KTH) istesting and developing a project entitled Heat on Wheels. The basic principle of this project is to collectsurplus heat of industry and to bring it to users – e.g. via a district heating network – using a phase changematerial (PCM) as an intermediate to store the energy and carry it from one point to another in a mobilethermal energy storage (M-TES) unit.This thesis takes part in testing the performances of Erythritol as a PCM storing and releasing energy in aprototype at KTH. The prototype consists of tube heat exchanger submerged in PCM. The HTF eithermelts the PCM (endothermic process) or freezes it (exothermic process). The M-TES storage density isaround 178 kWh/m3.The results show a 2.50 times longer charging time and a 1.62 times longer discharging time with a halvedHTF flow. Halving the HTF flow also leads to a 50 % decrease in power in the PCM over the wholecharge process. The power received by the HTF during the whole process is halved when increasing thedischarge HTF temperature by 33 %. The melting/freezing process of the PCM is dependent on thelocalization in the storage unit. Nevertheless, technical grade Erythritol seems to sustain repeatedwarming-cooling cycles, without noticeable storage degradation.The study also showed that with the proposed design, upscaling M-TES with a 700 % increase in lengthwould result in an overall heat transfer coefficient multiply on average by 7 ensuring thus an even fastercharge/discharge process.A recommendation for future work is to investigate how to homogenize the melting/freezing of the PCMin the heat exchanger, maybe by better spreading the HTF flow in between the pipes. It would also beadvantageous to work on reducing the losses in between the charge and the discharge in order to keep asmuch energy as possible. Further studies on the impact of upscaling the laboratory prototype can also beconducted, taking into account different designs such as a larger pipe diameter for instance.
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Cordeiro, Roberto. "Energy Storage System for Wind-Diesel Power System in Remote Locations". Thesis, Högskolan i Gävle, Energisystem, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-22534.
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The aim of this thesis is to show how much fuel can be saved in a power system based in diesel generators with integrated wind turbine (WDPS – Wind Diesel Power System) when a storage system is integrated. Diesel generator is still the most used power system for remote locations where the conventional grid doesn’t reach and its integration with wind turbine is seen as a natural combination to reduce diesel consumption. However, the wind intermittency brings some challenges that might prevent the necessary diesel savings to the level that justifies the integration with wind turbine. The introduction of a storage system can leverage the wind energy that would otherwise be wasted and use it during periods of high demand.The thesis starts by describing the characteristics of energy storage systems (ESS) and introducing the major ESS technologies: Flywheel, Pumped Hydro, Compressed Air and the four main battery technologies, Lead Acid, Nickel-Based, Lithium-ion and Sodium-Sulphur. The aim of this step it to obtain and compile major ESS parameters to frame then into a chart that will be used as a comparison tool.In the next step, wind-diesel power systems are described and the concept of Wind Penetration is introduced. The ratio between the wind capacity and diesel capacity determines if the wind penetration is low, medium and high and this level has a direct relation to the WDPS complexity. This step also introduces important concepts pertaining to grid load and how they are affected by the wind penetration.Next step shows the development of models for low, medium and high penetration WDPS with and without integrated ESS. Simulations are executed based on these models in order to determine the diesel consumption for each of them. The simulations are done by using reMIND tool.The final step is a comparative study where the most appropriated ESS technology is chosen based on adequacy to the system, system size and location. Once the technology is chosen, the ESS economic viability is determine based on the diesel savings obtained in the previous step.Since this is a general demonstration, no specific data about wind variation and consumer demand was used. The wind variation, which is used as the input for the wind turbine (WT), was obtained from a typical Weibull Distribution which is the kind of distribution that most approximate a wind pattern for long term data collection. The wind variation over time was then randomly generated from this distribution. The consumer load variation is based on a typical residential load curves. Although the load curve was generated randomly, its shape was maintained in conformity with the typical curves.This thesis has demonstrated that ESS integrated to WDPS can actually bring a reasonable reduction in diesel utilization. Even with a wind pattern with a low mean speed (5.31 m/s), the savings obtained was around of 17%.Among all ESS technologies studied, only Battery Energy Storage System (BESS) showed to be a viable technology for a small capacity WDPS. Among the four BESS technologies studied, Lead-Acid presents the highest diesel savings with the lower initial investment and shorter payback time.O objetivo dessa tese é determinar quanto combustível pode ser economizado quando se integra um sistema de armazenamento de energia (ESS na sigla em Inglês) a um sistema gerador baseado em gerador diesel integrado com turbina eólica (WDPS na sigla em Inglês). Geradores à diesel são largamente utilizados em áreas remotas onde a rede de distribuição de eletricidade não chega, e a integração de geradores à diesel com turbinas eólicas se tornou a combinação usual visando a economia de combustível. No entanto, a intermitência do vento cria alguns desafios que podem inclusive tornar essa integração inviável economicamente. A introdução de ESS à esse sistema visa o aproveitamento da energia que seria desperdiçada para usá-la em periodos de alta demanda.A tese começa descrevendo as características de ESS e suas principais tecnologias: Flyweel, hidroelétrica de bombeamento, ar-comprimido e as quatro principais tecnologias de bateria, Chumbo-Ácido, Níquel, Íon de Lítio e Sódio-Sulfúrico. O objetivo dessa etapa é obter os principais parâmetros de ESS e apresentá-los numa planilha para referência futura.Na etapa seguinte, geradores à diesel são descritos e é introduzido o conceito de Penetração do Vento. A razão entre a capacidade eólica e a capacidade do gerador diesel determina se a penetração é baixa, média ou alta, e esse nível tem uma relação direta com a complexidade do WDPS. Nessa etapa também são introduzidos importantes conceitos sobre demanda numa rede de distribuição de eletricidade e como esta é afetada pela penetração do vento.A etapa seguinte apresenta a modelagem de WDPS com baixa, média e alta penetração, incluindo a integração com ESS. Sobre esses modelos são então executadas simulações buscando determinar o consumo de diesel de cada um. As simulações são feitas usando a ferramenta reMIND.A última etapa é um estudo comparativo para determinar qual tecnologia de ESS é a mais apropriada para WDPS, levando-se em conta sua localização geográfica e capacidade. Uma vez que a escolha tenha sido feita, a viabilidade econômica do ESS é calculada baseado na ecomonia de combustível obtida na etepa anterior.Como esta tese apresenta uma demonstração, não foram utilizados dados reais de variação do vento nem de consumo. A variação do vento foi obtida de uma distribuição Weibull típica, que é a distribuição que mais se aproxima da característica do vento coletada em logo prazo. A variação do vento no tempo foi gerada aleatoriamente baseada nessa distribuição. A curva de consumo é baseada em curvas de consumo residenciais típicas. Embora a curva de consumo tenha sido gerada aleatoriamente, o seu formato foi mantido em conformidade com as curvas típicas.Essa tese demonstrou que ESS integrado à WDPS pode trazer uma economia razoável. Mesmo usando uma distribuição de vento com baixo valor médio (5.3 m/s), a economia obtida foi de 17%.Dentre as tecnologias de ESS pesquisadas, apenas o sistema de armazenamento com bateria (BESS na sigla em Inglês) se mostrou viável para um WDPS com pequena capacidade. Dentre as quatro tecnologias de BESS pesquisadas, Chumbo-Ácido foi a que apresentou a maior economia de diesel com o menor investimento inicial e com o menor tempo de retorno do investimento.
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Zhang, Xiaodong. "Power system transmission enhancement through storage". Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-11242009-020211/.
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Gupta, Sarthak. "Real-time Integration of Energy Storage". Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/78749.
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Increasing dynamics in power systems on account of renewable integration, electric vehicle penetration and rising demands have resulted in the exploration of energy storage for potential solutions. Recent technology- and industry-driven developments have led to a drastic decrease in costs of these storages, further advocating their usage. This thesis compiles the author's research on optimal integration of energy storage. Unpredictability is modelled using random variables favouring the need of stochastic optimization algorithms such as Lyapunov optimization and stochastic approximation. Moreover, consumer interactions in a competitive environment implore the need of topics from game theory. The concept of Nash equilibrium is introduced and methods to identify such equilibrium points are laid down. Utilizing these notions, two research contributions are made. Firstly, a strategy for controlling heterogeneous energy storage units operating at different timescales is put forth. They strategy is consequently employed optimally for arbitrage in an electricity market consisting of day-ahead and real-time pricing. Secondly, energy storages owned by consumers connected to different nodes of a power distribution grid are coordinated in a competitive market. A generalized Nash equilibrium problem is formulated for their participation in arbitrage and energy balancing, which is then solved using a novel emph{weighted} Lyapunov approach. In both cases, we design real-time algorithms with provable suboptimality guarantees in terms of the original centralized and equilibrium problems. The algorithms are tested on realistic scenarios comprising of actual data from electricity markets corroborating the analytical findings.Master of Science
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Niaparast, Shervin. "ENERGY ANALYSIS OF A SOLAR BLIND CONCEPT INTEGRATED WITH ENERGY STORAGE SYSTEM". Thesis, KTH, Kraft- och värmeteknologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-131419.
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The use of an attached sunspace is one of the most popular passive solar heating techniques. One of the main drawbacks of the sunspace is getting over heated by the sun energy during the hot season of the year. Even in northern climates overheating could be problematic and there is a considerable cooling demand. Shading is one of the most efficient and cost effective strategies to avoid overheating due to the high irradiation especially in the summer. Another strategy is using ventilation system to remove the excess heat inside the sunspace. However this rejected energy can be captured and stored for future energy demands of the sunspace itself or nearby buildings. Therefore the Solar blind system has been considered here for the shielding purpose in order to reduce the cooling demand. By considering the PV/T panels as the solar blind, the blocked solar energy will be collected and stored for covering part of the heating demand and the domestic hot water supplies of the adjacent building. From a modeling point of view, the sunspace can be considered as a small-scale closed greenhouse. In the closed greenhouse concept, available excess heat is indeed utilized in order to supply the heating demand of the greenhouse itself as well as neighboring buildings. The energy captured by PV/T collectors and the excess heat from the sunspace then will be stored in a thermal energy storage system to cover the daily and seasonal energy demand of the attached building. In the present study, a residential building with an attached sunspace with height, length and width of 3, 12 and 3.5 meters respectively has been assumed located in two different locations, Stockholm and Rome. Simulations have been run for the Solar blind system integrated with a short-term and a long-term TES systems during a year to investigate the influence of the sunspace equipped with a PV/T Solar blind on the thermal behavior of the adjacent building. The simulated results show that the Solar blind system can be an appropriate and effective solution for avoiding overheating problems in sunspace and simultaneously produce and store significant amount of thermal energy and electricity power which leads to saving considerable amount of money during a year.
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Piechowski, Miroslaw. "A ground coupled heat pump system with energy storage /". Connect to thesis, 1996. http://eprints.unimelb.edu.au/archive/00000724.
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Damnjanovic, Nenad. "Smart Grid Functionality of a PV-Energy Storage System". Scholar Commons, 2011. http://scholarcommons.usf.edu/etd/3058.
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Renewable Energy will be the key to preserving the Earth's remaining resources and continuing this surge of technological progress that we have experienced this past century. New philosophies of how/when/where energy should be consumed and produced are attempting to improve upon the current grid infrastructure. The massive advancement in communications, renewable and control systems will allow this new-age electric grid to maximize its efficiency while reducing cost. Renewable, "green" energy is now at the forefront of innovation. As the world population increases, there will be a need to free ourselves from natural resources as much as possible. Advanced Energy Storage Systems (AESS) will play a vital and large role in this new-age infrastructure. Because renewable energy is not constant (aside from hydroelectricity), this energy needs to be conserved and used at appropriate times. The Sustainable Electric Energy Delivery System (SEEDS) project features an AESS made from Lithium-ion phosphate (LiFeP04) and a Photovoltaic (PV) source connected to the grid. Every current technology has different parameters, efficiency, charge/discharge rates, lifespan, etc. The current Li-FeP04 system will be used as an example and a model. This project acts as a pilot project for future large scale smart grid endeavors. This thesis is written in conjunction with the SEEDS project and will outline and discuss in detail the findings. For the PV system, the performance is analyzed. For the storage system, the round-trip efficiency (measured) and life cycle are broken down. The thesis concludes with a capacity sizing estimation of the storage system which is based on the renewable energy source (solar).
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Neumann, Robert James. "Lifetime analysis of a composite flywheel energy storage system". Thesis, Queen Mary, University of London, 2001. http://qmro.qmul.ac.uk/xmlui/handle/123456789/26689.
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This thesis is concentrated on the long-term fracture of thick unidirectional glass and carbon fibre composites subjected to transverse stress. The objective was to develop a methodology for predicting the long term lifetime of a composite rotor used as part of a flywheel based energy storage system. The flywheel design is based on accommodating high hoop stresses induced during the high speed rotation. However, the different Poisson's ratios of the constituent materials in the rotor result in a complex stress distribution with significant stresses introduced in a direction transverse to the fibres. The possibility has been raised that the lifetime of the rotor will be limited by crack growth in this transverse direction, originating from defects (pores, cracks etc) that can be introduced into the rotor during its manufacture. The approach explored in this work has been to adopt a fracture mechanics based methodology whereby the rate of crack growth in a thick composite is measured as a function of an applied stress intensity. The basic fracture parameters for the material were measured such that the time taken for a crack to grow to a size sufficient to cause failure under an operating stress could be calculated. The materials were also examined to characterise the nature, size and extent of inherent defects. The stress distribution in the rotor under operating conditions was modelled using finite element analysis. The combination of information on inherent defects, stress directions and crack growth rates enable predictions to be made concerning the likely lifetime of the composites. Proof stress diagrams were also constructed in order to demonstrate an approach to product quality assurance testing. The end point of the work was to identify critical manufacturing defect sizes that could be tolerated under the specified operating conditions. The methodology developed for lifetime predictions was critically assessed and considered to be generally acceptable. The work did however raise some concerns regarding the applicability of a conventional fracture mechanics approach applied to heterogeneous composite systems where the size of the cracks are very small. It is recommended that future work should concentrate on studying this area with an emphasis on crack nucleation studies rather than on further crack propagation work.
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Zhang, Tan. "Adaptive Energy Storage System Control for Microgrid Stability Enhancement". Digital WPI, 2018. https://digitalcommons.wpi.edu/etd-dissertations/190.
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Microgrids are local power systems of different sizes located inside the distribution systems. Each microgrid contains a group of interconnected loads and distributed energy resources that acts as a single controllable entity with respect to the grid. Their islanding operation capabilities during emergencies improve the resiliency and reliability of the electric energy supply. Due to its low kinetic energy storage capacity, maintaining microgrid stability is challenging under system contingencies and unpredictable power generation from renewable resources. This dissertation highlights the potential benefits of flexibly utilizing the battery energy storage systems to enhance the stability of microgrids. The main contribution of this research consists in the development of a storage converter controller with an additional stability margin that enables it to improve microgrid frequency and voltage regulation as well as its induction motor post-fault speed recovery. This new autonomous control technique is implemented by adaptively setting the converter controller parameters based on its estimated phase-locked loop frequency deviation and terminal voltage magnitude measurement. This work also assists in the microgrid design process by determining the normalized minimum storage converter sizing under a wide range of microgrid motor inertia, loading and fault clearing time with both symmetrical and asymmetrical fault types. This study evaluates the expandability of the proposed control methodologies under an unbalanced meshed microgrid with fault-induced feeder switching and multiple contingencies in addition to random power output from renewable generators. The favorable results demonstrate the robust storage converter controller performance under a dynamic changing microgrid environment.
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Ocheme, Simon Eje. "Multiscale, multidimensional renewable energy generation and storage management system". Thesis, University of Leeds, 2017. http://etheses.whiterose.ac.uk/17698/.
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Hydrogen combined cooling heating and power system provides an efficient and holistic means of meeting multiscale and multidimensional energy demands through short, medium and long term storage. The energy generation consist of solar thermal heat, photovoltaic electricity and wind power. The energy storage consists of short term battery storage, medium term heat storage and long term hydrogen storage. The general focus is on the system level integration and simulation of the entire system and a particular focus on the parabolic trough receiver shape and the control at the low level, high level supervisory logic control that manages the entire system. Furthermore, the fabrication of an experimental rig is performed originally for the validation purposes of the thermal system, in which the heat transfer characteristics of different nanoliquids under different natural light conditions is assessed. The results show a good performance for control reference tracking and disturbance rejection of the solar radiation. Research on the shape optimisation of the receivers of the parabolic trough reveals that the triangular shape provides a superior performance compared to the classical semi-circular shape in absorbing solar radiation. Also, a system level control oriented model, supervisory energy management system and experimental measurement system to study hydrogen combined cooling power system has been developed. The computational and experimental models developed in this research programme provide a strong basis for further studies, including the analysis and operation of hybrid hydrogen combined cooling energy system in the real tracking space and its overall system control and optimisation.
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Qian, Hao. "A High-Efficiency Grid-Tie Battery Energy Storage System". Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/29008.
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Lithium-ion based battery energy storage system has become one of the most popular forms of energy storage system for its high charge and discharge efficiency and high energy density. This dissertation proposes a high-efficiency grid-tie lithium-ion battery based energy storage system, which consists of a LiFePO4 battery based energy storage and associated battery management system (BMS), a high-efficiency bidirectional ac-dc converter and the central control unit which controls the operation mode and grid interface of the energy storage system. The BMS estimates the state of charge (SOC) and state of health (SOH) of each battery cell in the pack and applies active charge equalization to balance the charge of all the cells in the pack. The bidirectional ac-dc converter works as the interface between the battery pack and the ac grid, which needs to meet the requirements of bidirectional power flow capability and to ensure high power factor and low THD as well as to regulate the dc side power regulation.
A highly efficient dual-buck converter based bidirectional ac-dc converter is proposed. The implemented converter efficiency peaks at 97.8% at 50-kHz switching frequency for both rectifier and inverter modes. To better utilize the dc bus voltage and eliminate the two dc bus bulk capacitors in the conventional dual-buck converter, a novel bidirectional ac-dc converter is proposed by replacing the capacitor leg of the dual-buck converter based single-phase bidirectional ac-dc converter with a half-bridge switch leg. Based on the single-phase bidirectional ac-dc converter topology, three novel three-phase bidirectional ac-dc converter topologies are proposed.
In order to control the bidirectional power flow and at the same time stabilize the system in mode transition, an admittance compensator along with a quasi-proportional-resonant (QPR) controller is adopted to allow smooth startup and elimination of the steady-state error over the entire load range. The proposed QPR controller is designed and implemented with a digital controller. The entire system has been simulated in both PSIM and Simulink and verified with hardware experiments. Small transient currents are observed with the power transferred from rectifier mode to inverter mode at peak current point and also from inverter mode to rectifier mode at peak current point.
The designed BMS monitors and reports all battery cells parameters in the pack and estimates the SOC of each battery cell by using the Coulomb counting plus an accurate open-circuit voltage model. The SOC information is then used to control the isolated bidirectional dc-dc converter based active cell balancing circuits to mitigate the mismatch among the series connected cells. Using the proposed SOC balancing technique, the entire battery storage system has demonstrated more capacity than the system without SOC balancing.Ph. D.
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Gong, Yifu. "Intelligent Energy-Efficient Storage System for Big-Data Applications". Diss., North Dakota State University, 2020. https://hdl.handle.net/10365/31752.
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Static Random Access Memory (SRAM) is a critical component in mobile video processing systems. Because of the large video data size, the memory is frequently accessed, which dominates the power consumption and limits battery life. In energy-efficient SRAM design, a substantial amount of research is presented to discuss the mechanisms of approximate storage, but the content and environment adaptations were never a part of the consideration in memory design. This dissertation focuses on optimization methods for the SRAM system, specifically addressing three areas of Intelligent Energy-Efficient Storage system design. First, the SRAM stability is discussed. The relationships among supply voltage, SRAM transistor sizes, and SRAM failure rate are derived in this section. The result of this study is applied to all of the later work. Second, intelligent voltage scaling techniques are detailed. This method utilizes the conventional voltage scaling technique by integrating self-correction and sizing techniques. Third, intelligent bit-truncation techniques are developed. Viewing environment and video content characteristics are considered in the memory design. The performance of all designed SRAMs are compared to published literature and are proven to have improvement.
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Wu, Ding. "Control of a super-capacitor based energy storage system". Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/control-of-a-supercapacitor-based-energy-storage-system(e43378a8-22ec-442a-bc87-df4adb5fb3cb).html.
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The increasing use of electrical technologies within on-board (aircraft, road vehicle, train and ship) power systems is resulting in complex and highly dynamic networks in which energy storage devices have an important role to play, for example to resolve the instantaneous mismatch between load demand and power availability or to provide the flexibility to optimise overall performance. In this thesis, a multi-level controller for a super-capacitor based energy storage system (ESS) is designed, simulated, emulated and validated experimentally to show its effectiveness in smoothing load and managing state-of-charge of the energy storage system. This thesis first investigates the low level control of the dual-interleaved converter, particularly at light load where seven discontinuous conduction modes (DCMs) appear. A thorough analysis of these operating modes is given and validated by simulations and experiments. Based on the analysis, an inverse-model-based feed-forward current controller is implemented, offering a low level converter control interface which serves the high level supervisory controller within the energy storage system. Two supervisory control methods have been proposed in this thesis, both producing a super-capacitor current reference for the low level controller. The first supervisory control not only manages the energy within the ESS but also shields the primary power source from rapid load transients , which has been examined through an emulated ESS in the Intelligent Electrical Power Network Evaluation Facility (IEPNEF). A more advanced supervisory controller is then proposed which in addition to the benefits of the first control, regulates the rate-of-change in power that is drawn from the primary power source in the system. The proposed second control method is implemented within a real super-capacitor energy storage system in IEPNEF, with both simulation and experimental results successfully demonstrating and validating its operation.
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Bajracharya, Quree. "Dynamic Modeling, Monitoring and Control of Energy Storage System". Thesis, Karlstads universitet, Fakulteten för teknik- och naturvetenskap, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-26521.
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Today there is a great interest on the small scale renewable electricity generation due to the changing economics and the demand for highly sustainable electricity generation. However, renewable energy sources are unreliable and fluctuating which causes variation of power flow. In this situation, there can be server problems such as frequency oscillations, violation of the power line capability jeopardizing the security of the power system. Batteries can be an emerging technology which acts as the fast acting spinning reserve that can balance between the load and generation. Conversely, it very difficult to accurately predict battery performance and the total cost of the investment of storage system by integrating batteries to the renewable system as batteries in this situation have to bear a wide range of the operational conditions . Henceforth, modeling of the battery is extremely important. This master thesis gives the dynamic modeling of the batteries which can replicate the relevant behavior of the battery. The proposed methodology is the model based approach where the parameters are determined to develop a suitable model. In this thesis, the battery is modeled as an R-C circuit comprising of elements each of which represents certain battery characteristics. An appropriate model is selected based on the comparative study of the characteristics of experimental output of the battery using model identification. Parameters of the battery are computed in the MATLAB Simulink parameter estimation toolbox using least square estimation .The initial parameter values for the simulink are found with the help of the lab test. Validation results from the two experimental data shows that the model can accurately estimate the battery characteristics with an error of 0.3%.The aforementioned battery model is later used to make an appropriate charge controller. The methods used in the thesis performed quite well within the limited tests performed during the experimental works. To use the model online in the future, further investigation is recommended in order to refine the model.
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Robbins, Curt. "Small scale renewable energy storage system using hydrogen combustion". abstract and full text PDF (UNR users only), 2008. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1456487.
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Leuschke, Rainer. "Motor integrated actuation for a flywheel energy storage system /". Thesis, Connect to this title online; UW restricted, 2004. http://hdl.handle.net/1773/7113.
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Wang, Chengrui. "Application of Nano-Functional Materials in Energy Storage System". Thesis, Griffith University, 2020. http://hdl.handle.net/10072/392036.
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Energy problem has become one of the most important problems in today's world. With the depletion of fossil fuels and the change of climate, the research on the conversion and application of new clean energy has entered a critical stage. With the deepening of research, more and more technologies and products have been commercialized and changed our daily life, such as electric vehicles (EVs). EVs refer vehicles which are powered by electric energy (lithium ion batteries). Compared with traditional fuel cars, electric vehicles (EVs) have many advantages: (i) High energy efficiency: The energy conversion efficiency of the fuel engine is only about 10%-15%, while the efficiency of the battery engine can be as high as 80%-90%; (ii) Environmentally friendly: The emissions of petrol cars include solid particles, carbon oxides, nitrogen oxides, sulphur oxides, etc, while the batteries almost have no pollution emissions; (iii) Economy: The average cost of EVs is about 4.2AUD per 100km, while the cost of petrol vehicles is about 18.7AUD per 100km. According to these obvious advantages, many countries have already announced plans to increase the uptake the of electric vehicles.
These applications demand an increased performance from the lithium-ion battery (LIB). Although this technology is quite mature after years of development, there are still many problems today. For cathode materials, the main problem is that the specific capacity is relatively low and not suited to high energy applications. For anode materials, although the specific capacity is quite good, the stability is a big problem. In addition, the safety and the high cost are also problems demanding prompt solutions. At the same time, the lithium mineral on earth is being exhausted, finding other alkaline metals, like sodium or potassium, to replace lithium is also a major direction of energy storage research.
This thesis presents four research works during my doctoral study which are mainly about the electrode materials of four different battery systems. The purposes of these works are to improve the problems existing in the traditional materials through the way of composition design and morphology control.
The first two chapters of my work are about the symmetric battery system. The symmetric batteries with an electrode material possessing dual cathodic and anodic properties have been regarded as an ideal battery configuration because of their distinctive advantages over the asymmetric batteries in terms of fabrication process, cost and safety concerns. However, the development of good performance in symmetric batteries is highly challenging due to the very limited availability of suitable symmetric electrode materials with such duplex properties of high reversible capacity. Chapter 2 introduces a triple-hollow-shell structured V2O5 (THS-V2O5) based high performance symmetric electrode material with a reversible capacity of >400mAh/g between 1.5V to 4.0V and >600mAh/g between 0.1V to 3.0V, respectively, when used as the cathode and anode. This single electrode based symmetric full lithium ion battery (LIB) constructed with THS-V2O5 exhibits a reversible capacity of about 290mAh/g between 2.0V to 4.0V, which is the best performance in symmetric energy storage systems reported to date. In Chapter 3, we report a novel NASICON-type K3V2(PO4)3 which was prepared and first employed for the symmetric KIBs. The reversible capacity of the full symmetric KIBs is about 90mAh/g between 0.01–3.0V at 25mA/g, corresponding to an initial coulombic efficiency of 91.7%. Additionally, a potential of about 2.3V was obtained in this work, which is the largest reported working potential and will benefit the output energy of this symmetric energy storage system.
The other two chapters of my work are about anode materials of lithium-ion batteries (LIBs). In Chapter 4, we reported a new yolk-shell structured high tap density composite made of a carbon-coated rigid SiO2 outer shell to confine multiple Si nanoparticles (NPs) (yolks) and carbon nanotubes (CNTs) with embedded Fe2O3 NPs. The achieved high tap density and superior conductivity can be attributed to the efficiently utilised inner void by multiple Si yolks, Fe2O3 NPs and CNTs Li+ storage materials, and the bridged spaces between the inner Si yolks and outer shell through a conductive CNTs. In Chapter 5, we present a controllable synthesis method of single to quadruple hollow NiO multi-shelled microspheres and studied the electrochemical properties. Furthermore, we made a modification on the basis of the triple-shelled structure, the hollow triple-shelled α-Fe2O3/NiFe2O4@NiO (TS-NFO) microspheres were simply synthesized by a secondary absorption method. Due to the effect of synergistically interactive, the TS-NFO microspheres exhibited an initial capacity of 2474mAh·g-1 and excellent reversible capacity of 869mAh·g-1, 2114mAh·g-1, 2061mAh·g-1 after 100, 500 and 800 cycles at 0.5A·g-1 in the electrochemistry property tests. The outstanding energy storage performance can be ascribed to the unique hollow hybrid metal oxides core@shelled structure, which can relieve the volume extension to a great extent and greatly improve the reversible specific capacity by the synergistically interactive effect.
In summary, this thesis introduces four kinds of electrode materials, which are applied to two kinds of energy storage systems. All the research works were trying to improve the performance of the batteries by composition design and morphology control, which may provide new ideas for the study of functional electrode materials development for energy storage systems.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Environment and Sc
Science, Environment, Engineering and Technology
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Alajo, Oluwaseun Sunday. "EXPERIMENTAL CHARACTERIZATION OF A PCM SOLAR ENERGY STORAGE SYSTEM". OpenSIUC, 2013. https://opensiuc.lib.siu.edu/theses/1246.
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This study is on the development and characterization of a phase change material (PCM)-based solar energy storage system. An evacuated tube solar collector was used to transfer thermal energy to water circulated by a solar-operated pump. The water flows through a heat exchanger embedded in the phase change material in a storage tank, thus transferring energy to the PCM which changes phase and stores thermal energy. The system is completely renewable as solar energy conversion was applied in the system to power all the electrical components. The PCM used in this system is vegetable-based, therefore non-toxic. Analytical and experimental studies were performed to investigate the performance of the system. Average thermal energy stored over the six months of testing was 50.63 MJ with just about 45 kg of PCM. The system performed best in the summer period with an efficiency of 63.6% when the lowest thermal energy loss was recorded. A low heat transfer fluid flowrates of 3 L/min (0.05 kg/s) and 2 L/min (0.033 kg/s) produced the best heat storage and heat recovery processes respectively.
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Yunus, A. M. Shiddiq. "Application of SMES Unit to improve the performance of doubly fed induction generator based WECS". Thesis, Curtin University, 2012. http://hdl.handle.net/20.500.11937/1450.
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Due to the rising demand of energy over several decades, conventional energy resources have been continuously and drastically explored all around the world. As a result, global warming is inevitable due to the massive exhaust of CO2 into the atmosphere from the conventional energy sources. This global issue has become a high concern of industrial countries who are trying to reduce their emission production by increasing the utilization of renewable energies such as wind energy. Wind energy has become very attractive since the revolution of power electronics technology, which can be equipped with wind turbines. Wind energy can be optimally captured with wind turbine converters. However, these converters are very sensitive if connected with the grid as grid disturbances may have a catastrophic impact on the overall performance of the wind turbines.In this thesis, superconducting magnetic energy storage (SMES) is applied on wind energy conversion systems (WECSs) that are equipped with doubly fed induction generators (DFIGs) during the presence of voltage sags and swells in the grid side. Without SMES, certain levels of voltage sags and swells in the grid side may cause a critical operating condition that may require disconnection of WECS to the grid. This condition is mainly determined by the voltage profile at the point of common coupling (PCC), which is set up differently by concerned countries all over the world. This requirement is determined by the transmission system operator (TSO) in conjunction with the concerned government. The determined requirement is known as grid codes or fault ride through (FRT) capability.The selection of a SMES unit in this thesis is based on its advantages over other energy storage technologies. Compared to other energy storage options, the SMES unit is ranked first in terms of highest efficiency, which is 90-99%. The high efficiency of the SMES unit is achieved by its low power loss because electric currents in the coil encounter almost no resistance and there are no moving parts, which means no friction losses. Meanwhile, DFIG is selected because it is the most popular installed WECS over the world. In 2004 about 55% of the total installed WECS worldwide were equipped with DFIG. There are two main strategies that can be applied to meet the grid requirements of a particular TSO. The first strategy is development of new control techniques to fulfil the criterion of the TSOs. This strategy, however, is applicable only to the new WECS that have not been connected to the power grid. If new control techniques are applied to the existing gridconnected WECSs, they will not be cost effective because the obsolete design must be dismantled and re-installed to comply with current grid code requirements. The second strategy is the utilization of flexible AC transmission system (FACTS) devices or storage energy devices to meet the grid code requirements. This strategy seems more appropriate for implementation in the existing WECS-grid connection in order to comply with the current grid code requirements. By appropriate design, the devices might be more cost effective compared to the first strategy, particularly for the large wind farms that are already connected to the grid.A new control algorithm of a SMES unit, which is simple but still involves all the important parameters, is employed in this study. Using the hysteresis current control approach in conjunction with a fuzzy logic controller, the SMES unit successfully and effectively improves the performance of the DFIG during voltage sag and swell events in the grid side; thus, this will prevent the WECS equipped with DFIG from being disconnected from the grid according to the selected fault ride through used in this study. The dynamic study of DFIG with SMES during short load variation is carried out as an additional advantage of SMES application on a DFIG system. In this study, the proposed SMES unit is controlled to compensate the reduced transfer power of DFIG during the short load variation event. Moreover, the SMES unit is also engaged in absorbing/storing some amount of excessive power that might be transferred to the grid when the local loads are suddenly decreased. Finally, the studies of intermittent misfires and fire-through that take place within the converters of DFIG are carried out in order to investigate the impact of these converter faults on the performance of DFIG. In this part, the proposed SMES unit is controlled to effectively improve the DFIG’s performance in order to prevent it from being disconnected or shut down from the power grid during the occurrence of these intermittent switching faults.
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Maidadi, Mohaman Bello. "Packed-bed rock thermal energy storage for concetrated solar power: enhancement of storage time and system efficiency". Thesis, Nelson Mandela Metropolitan University, 2013. http://hdl.handle.net/10948/d1020914.
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Solar thermal energy harvesting is a promising solution to offset the electricity demands of a growing population. The use of the technology is however still limited and this can most likely be attributed to the capital cost and also the intermittent nature of solar energy which requires incorporation of a storage system. To make the technology more attractive and effective, cheap means of harvesting solar energy and the development of efficient and inexpensive thermal energy storage devices will improve the performance of solar energy systems and the widespread use of solar energy. Heat storage in a packed-bed rock with air as the working fluid presents an attractive and simple solution for storing solar thermal energy and it is recommended for solar air heaters. A packed-bed rock storage system consists of rocks of good heat capacity packed in a storage tank. The working fluid (air) flows through the bed to transfer its energy. The major concern of the design for a packed-bed rock thermal storage system is to maximize the heat transfer and minimise the pressure drop across the storage tank and hence the pumping power. The time duration the stored energy can be preserved and the air flow wall effect through the bed are the common complications encountered in this system. This study presents an experimental and analytical analysis of a vacuum storage tank with the use of expanded perlite for high temperature thermal energy storage in a packed-bed of rocks. Dolerite rocks are used as the storage medium due to their high heat capacity and as they are locally available. To minimise the pressure drop across the tank, moderate rock sizes are used. The tank contains baffles, allowing an even spread of air to rock contact through the entire tank, therefore improving heat transfer. There is a good correlation between the predicted and the actual results (4 percent) which implies that the baffles incorporated inside the vacuum tank forces the air through the entire tank, thereby resulting in an even lateral temperature distribution across the tank. The investigation of heat loss showed that a vacuum with expanded perlite is a viable solution to high temperature heat storage for an extended period. The research also focuses on the investigation of a proposed low cost parabolic trough solar collector for an air heating system as shown in Figure (1.3). The use of a standard solar geyser evacuated tube (@R130 each) has cost benefits over the industry standard solar tubes normally used in concentrating solar power systems. A mathematical was developed to predict the thermal performance of proposed PTC and it was found that the measured results compared well with the predictions. The solar energy conversion efficiency of this collector is up to 70 percent. This research could impact positively on remote rural communities by providing a source of clean energy, especially for off-grid applications for schools, clinics and communication equipment. It could lead to a significant improvement in the cost performance, ease of installation and technical performance of storage systems for solar heating applications.
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Behzadnia, Peyman. "Dynamic Energy-Aware Database Storage and Operations". Scholar Commons, 2018. http://scholarcommons.usf.edu/etd/7125.
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Energy consumption has become a first-class optimization goal in design and implementation of data-intensive computing systems. This is particularly true in the design of database management systems (DBMS), which is one of the most important servers in software stack of modern data centers. Data storage system is one of the essential components of database and has been under many research efforts aiming at reducing its energy consumption. In previous work, dynamic power management (DPM) techniques that make real-time decisions to transition the disks to low-power modes are normally used to save energy in storage systems. In this research, we tackle the limitations of DPM proposals in previous contributions and design a dynamic energy-aware disk storage system in database servers. We introduce a DPM optimization model integrated with model predictive control (MPC) strategy to minimize power consumption of the disk-based storage system while satisfying given performance requirements. It dynamically determines the state of disks and plans for inter-disk data fragment migration to achieve desirable balance between power consumption and query response time. Furthermore, via analyzing our optimization model to identify structural properties of optimal solutions, a fast-solution heuristic DPM algorithm is proposed that can be integrated in large-scale disk storage systems, where finding the most optimal solution might be long, to achieve near-optimal power saving solution within short periods of computational time. The proposed ideas are evaluated through running simulations using extensive set of synthetic workloads. The results show that our solution achieves up to 1.65 times more energy saving while providing up to 1.67 times shorter response time compared to the best existing algorithm in literature.
Stream join is a dynamic and expensive database operation that performs join operation in real-time fashion on continuous data streams. Stream joins, also known as window joins, impose high computational time and potentially higher energy consumption compared to other database operations, and thus we also tackle energy-efficiency of stream join processing in this research. Given that there is a strong linear correlation between energy-efficiency and performance of in-memory parallel join algorithms in database servers, we study parallelization of stream join algorithms on multicore processors to achieve energy efficiency and high performance. Equi-join is the most frequent type of join in query workloads and symmetric hash join (SHJ) algorithm is the most effective algorithm to evaluate equi-joins in data streams. To best of our knowledge, we are the first to propose a shared-memory parallel symmetric hash join algorithm on multi-core CPUs. Furthermore, we introduce a novel parallel hash-based stream join algorithm called chunk-based pairing hash join that aims at elevating data throughput and scalability. We also tackle parallel processing of multi-way stream joins where there are more than two input data streams involved in the join operation. To best of our knowledge, we are also the first to propose an in-memory parallel multi-way hash-based stream join on multicore processors. Experimental evaluation on our proposed parallel algorithms demonstrates high throughput, significant scalability, and low latency while reducing the energy consumption. Our parallel symmetric hash join and chunk-based pairing hash join achieve up to 11 times and 12.5 times more throughput, respectively, compared to that of state-of-the-art parallel stream join algorithm. Also, these two algorithms provide up to around 22 times and 24.5 times more throughput, respectively, compared to that of non-parallel (sequential) stream join computation where there is one processing thread.
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Ma, Anthony Winston. "Modeling and Analysis of a Photovoltaic System with a Distributed Energy Storage System". DigitalCommons@CalPoly, 2012. https://digitalcommons.calpoly.edu/theses/727.
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As California continues to integrate more renewable energy into its electrical system, the state has experienced a corresponding rise in photovoltaic system installations. PV arrays are a unique source of power generation in that they are affected by the location of the sun, shading, and temperature changes. These characteristics make solar one of the most highly variable forms of renewable energy. In order to improve solar power’s consistency, PV systems require a supplemental source of power. The primary focus of this paper is to determine if distributed energy storage systems can be used to reduce the effect of solar intermittency. This paper examines the test data and system specifications of an experimental DESS. The benefits of using a DESS in a PV system are further studied using computer simulation modeling. This paper also shows through computer simulations how a maximum power point tracker can increase a PV array’s power output. The results of this thesis demonstrate that DESS’s are capable of smoothing out highly variable load profiles caused by intermittent solar power.
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Carneheim, Stina. "Energy Storage System for Local Generation in a Grid-connected Microgrid : Sizing and analyzing an energy storage system for the Tezpur University campus". Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-276944.
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Reducing the emissions is an important step in orderto reduce the global warming. At Tezpur University in the Assamregion in Northeast India a project is being performed which willtry to reduce the use of diesel for back-up generation and partlyreplace this with other sources of energy. In 2018 a 1 MW PVplantwas installed as a part of this goal. However, since theconsumption and the PV-production are not synchronized someof the energy goes to waste.This thesis will consider how an energy storage system (ESS)can help to increase the usage of the power produced by thePV-plant. It will also assess the best type and size of the system.In addition to this, a simple economical analysis was performedto determine the profitability of the project.First, data regarding the system at Tezpur University wasgathered. The data of interest was the production of the PVpanels as well as the consumption. This data was then processedso that the consumption and production could be observedfor each hour a typical day. By comparing these two theoverproduction which goes to waste could be estimated. Byevaluating how much energy produced from diesel which couldbe replaced by the ESS an assessment of the savings per yearcould be made. From this the payback period was calculated forthe different size ESS.The results show that a battery energy storage system (BESS)using lithium-ion batteries is the preferred solution in this case.Assuming that 50 % of the life expectancy of a battery is areasonable payback period the maximum size of the battery is127 kWh. The optimal placement of the BESS is at substation 4as the overproduction is the greatest in this area and as there isalso a large load the stored energy would be used fully each day.A battery size of 90 kWh was suggested by the E4T MicroGridproject and considering the payback period this is a reasonablesize for the BESS.Att minska utsläppen är ett viktigt steg iatt minska den globala uppvärmningen. Vid Tezpur Universiteti Assam i nordöstra Indien genomförs nu ett projekt somskall minska användningen av diesel vid avbrott genom attdelvis ersätta dessa generatorer med andra energikällor. 2018installerades ett solkraftverk om 1 MW som en del i detta mål.Eftersom konsumtionen och produktionen från solkraftverketinte är helt synkroniserade är det delar av den produceradeelektriciteten som skickas tillbaka ut i nätet och därmed gårförlorad.Det här projektet har undersökt hur ett energilagringssystemkan användas för att öka användningen av energin produceradav solkraftverket. En annan del som undersökts är vilken typav system och vilken storlek det bör ha. Efter detta görs enenkel ekonomisk analys för att utreda hur ekonomiskt gynnsamtprojektet är.Det första som gjordes var att samla data om microsystemetpå Tezpur Universitet. Den data som samlades var om produktionenfrån solkraftverket och elkonsumtionen i de olika delarnaav universitetet. Genom olika metoder kunde man undersökahur konsumtionen och produktionen var per timme en typiskdag. Då man jämförde dessa kunde överproduktionen per dagestimeras. Besparingarna som görs beräknades genom att bytaut en del av dieselanvändningen med kostnaden av att laddaenergilagringssystemet. Detta gav tillräckligt med information föratt uppskatta återbetalningsperioden.Den bästa lösningen i det här fallet är att installera ettbatterilagringssystem bestående av litiumjonbatterier. Under antagandetatt återbetalningsperioden maximalt får var 50 % avlivslängden av batteriet kommer den största tillåtna storlekenatt vara 127 kWh. Den optimala placeringen av systemet ärvid transformatorstation 4 eftersom det är där som större delenav överproduktionen uppstår. Det är även till den som störredelen av lasten är kopplad vilket garanterar att hela batterietsladdning kan användas varje dag. Batteristorleken om 90 kWhsom föreslås i E4T MicroGrid-projektet är en bra storlek medtanke på återbetalningsperioden.
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Zhang, Tan. "The Economic Benefits of Battery Energy Storage System in Electric Distribution System". Digital WPI, 2013. https://digitalcommons.wpi.edu/etd-theses/298.
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The goal of this study was to determine the economic feasibility of battery energy storage system (BESS). Three major economic benefits derived from BESS using were studied: 1. Energy Purchase Shifting, 2. Distribution Feeder Deferral, 3. Outage Avoidance. The economic analysis was based on theoretical modeling of the BESS and distribution system. Three simulation models were developed to quantify the effects of different parameters, such as: BESS round-trip efficiency, life span, rated power, rated discharge time, marginal cost of electric energy, 24 h feeder load profile, annual load variation, feeder load growth rate and feeder length. An optimal battery charging/discharging method was presented to determine the differential cost of energy (DCE). The annual maximum DCE was calculated using stochastic probability analysis on seasonal load variation. The net present value was evaluated as the present value difference between two investments: first, the distribution feeder upgrade without BESS deferral, and second, with BESS deferral. Furthermore, the BESS’s contributions under different outage strategies were compared. It was determined that feeder length is the most significant parameter. The economics of the studied system becomes favorable when the feeder length exceeds a critical value.
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Khan, Muhammad Shahid. "Supervisory Hybrid Control of a Wind Energy Conversion and Battery Storage System". Thesis, 2008. http://hdl.handle.net/1807/11218.
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This thesis presents a supervisory hybrid controller for the automatic operation and control of a wind energy conversion and battery storage system.
The supervisory hybrid control scheme is based on a radically different approach of modeling and control design, proposed for the subject wind energy conversion and battery storage system.
The wind energy conversion unit is composed of a 360kW horizontal axis wind turbine
mechanically coupled to an induction generator through a gearbox. The assembly is electrically interfaced to the dc bus through a thyristor-controlled rectifier to enable variable speed operation of the unit. Static capacitor banks have been used to meet reactive power requirements of the
unit. A battery storage device is connected to the dc bus through a dc-dc converter to support operation of the wind energy conversion unit during islanded conditions. Islanding is assumed to occur when the tiebreaker to the utility feeder is in open position. The wind energy conversion
unit and battery storage system is interfaced to the utility grid at the point of common coupling through a 25km long, 13.8kV feeder using a voltage-sourced converter unit. A bank of static
(constant impedance) and dynamic (induction motor) loads is connected to the point of common coupling through a step down transformer.
A finite hybrid-automata based model of the wind energy conversion and storage system has
been proposed that captures the different operating regimes of the system during grid-connected and in islanded operating modes. The hybrid model of the subject system defines allowable operating states and predefines the transition paths between these operating states. A modular
control design approach has been adapted in which the wind energy conversion and storage
system has been partitioned along the dc bus into three independent system modules. Traditional control schemes using linear proportional-plus-integral compensators have been used for each system module with suitable modifications where necessary in order to achieve the required
steady state and transient performance objectives. A supervisory control layer has been used to combine and configure control schemes of the three system modules to suite the requirements of system operation during any one operating state depicted by the hybrid model of the system. Transition management strategies have been devised and implemented through the supervisory control layer to ensure smooth inter-state transitions and bumpless switching among controllers.
It has been concluded based on frequency domain linear analysis and time domain
electromagnetic transient simulations that the proposed supervisory hybrid controller is capable of operating the wind energy conversion and storage system in both grid-connected and in islanded modes under changing operating conditions including temporary faults on the utility
grid.
44
Le, Ha Thu. "Increasing wind power penetration and voltage stability limits using energy storage systems". Thesis, 2010. http://hdl.handle.net/2152/ETD-UT-2010-05-864.
Texto completo da fonteResumo:
The research is motivated by the need to address two major challenges in wind power integration: how to mitigate wind power fluctuation and how to ensure stability of the farm and host grid. It is envisaged that wind farm power output fluctuation can be reduced by using a specific type of buffer, such as an energy storage system (ESS), to absorb its negative impact. The proposed solution, therefore, employs ESS to solve the problems. The key research findings include a new technique for calculating the desired power output profile, an ESS charge-discharge scheme, a novel direct-calculation (optimization-based) method for determining ESS optimal rating, and an ESS operation scheme for improving wind farm transient stability. Analysis with 14 wind farms and a compressed-air energy storage system (CAES) shows that the charge-discharge scheme and the desired output calculation technique are appropriate for ESS operation. The optimal ESSs for the 14 wind farms perform four or less switching operations daily (73.2%-85.5% of the 365 days) while regulating the farms output variation. On average, the ESSs carry out 2.5 to 3.1 switching operations per day. By using the direct-calculation method, an optimal ESS rating can be found for any wind farm with a high degree of accuracy. The method has a considerable advantage over traditional differential-based methods because it does not require knowledge of the analytical form of the objective function. For ESSs optimal rating, the improvement in wind energy integration is between 1.7% and 8%. In addition, a net increase in grid steady-state voltage stability of 8.3%-18.3% is achieved by 13 of the 14 evaluated ESSs. For improving wind farm transient stability, the proposed ESS operation scheme is effective. It exploits the use of a synchronous-machine-based ESS as a synchronous condenser to dynamically supply a wind farm with reactive power during faults. Analysis with an ESS and a 60-MW wind farm consisting of stall-regulated wind turbines shows that the ESS increases the farm critical clearing time (CCT) by 1 cycle for worst-case bolted three-phase-to-ground faults. For bolted single-phase-to-ground faults, the CCT is improved by 23.1%-52.2%.text
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LANNA, ANDREA. "Control strategies for the integration of renewable energy sources in distribution and transmission networks". Doctoral thesis, 2016. http://hdl.handle.net/11573/875275.
Texto completo da fonteResumo:
This PhD thesis presents an innovative control strategy for the integration of renewable energy sources in distribution and transmission networks. This work is based on a multilevel control approach that takes into account the current technology, state of the art and legislative limits and considering the most promising trends.
The outer loop control is based on a real time strategy for optimal power flow in presence of storage devices and wind turbine driven by Doubly Fed Induction Generators. These elements work in cooperation defining a dy- namic bus where the generated power is subject to temporal constraints, which establish a coupling between traditional power flow problems related to consecutive time periods; further the uncertainty in wind power genera- tion forecasts requires a continuous update of the planned power profiles, in order to guarantee a dynamic equilibrium among demand and supply. Model predictive control is used for this purpose, considering the dynamic equations of the storage and the wind turbine rotor as prediction models. A proper target function is introduced in order to find a trade-off between the need of minimizing generation costs and the excursions of the storage state of charge and the wind turbine angular speed from reference states. In the case study under consideration storage, wind turbines and a traditional synchronous generator are operated by the Transmission System Operator in the form of a Virtual Power Plant to cover network losses.
The inner loop control is based on a real time control strategy for dy- namically balancing electric demand and supply at local level, in a scenario characterized by a HV/MV substation with the presence of renewable energy sources in the form of photovoltaic generators and an electric energy storage system. The substation is connected to the grid and is powered by an equiv- alent traditional power plant playing the role of the bulk power system. A model predictive control approach is proposed to decide in time the storage setpoint, based on the storage state of charge, the forecast demand and the forecast output of renewable plants.
The two loops allow to obtain an overall control system able to minimize the generation of traditional power systems during the day-ahead market in an hand, and to respect the local load forecasts in other hand thanks the introduction of non-dispatchable renewable energy system and the energy storage ones as well as an innovative predictive control strategy.
Theoretical results are reported on the stability of the proposed control scheme, which is then validated also on a simulation basis. Simulations show the effectiveness of the proposed approach in managing fluctuations of network demand and renewable generation under realistic conditions.This PhD thesis presents an innovative control strategy for the integration of renewable energy sources in distribution and transmission networks. This work is based on a multilevel control approach that takes into account the current technology, state of the art and legislative limits and considering the most promising trends. The outer loop control is based on a real time strategy for optimal power flow in presence of storage devices and wind turbine driven by Doubly Fed Induction Generators. These elements work in cooperation defining a dy- namic bus where the generated power is subject to temporal constraints, which establish a coupling between traditional power flow problems related to consecutive time periods; further the uncertainty in wind power genera- tion forecasts requires a continuous update of the planned power profiles, in order to guarantee a dynamic equilibrium among demand and supply. Model predictive control is used for this purpose, considering the dynamic equations of the storage and the wind turbine rotor as prediction models. A proper target function is introduced in order to find a trade-off between the need of minimizing generation costs and the excursions of the storage state of charge and the wind turbine angular speed from reference states. In the case study under consideration storage, wind turbines and a traditional synchronous generator are operated by the Transmission System Operator in the form of a Virtual Power Plant to cover network losses. The inner loop control is based on a real time control strategy for dy- namically balancing electric demand and supply at local level, in a scenario characterized by a HV/MV substation with the presence of renewable energy sources in the form of photovoltaic generators and an electric energy storage system. The substation is connected to the grid and is powered by an equiv- alent traditional power plant playing the role of the bulk power system. A model predictive control approach is proposed to decide in time the storage setpoint, based on the storage state of charge, the forecast demand and the forecast output of renewable plants. The two loops allow to obtain an overall control system able to minimize the generation of traditional power systems during the day-ahead market in an hand, and to respect the local load forecasts in other hand thanks the introduction of non-dispatchable renewable energy system and the energy storage ones as well as an innovative predictive control strategy. Theoretical results are reported on the stability of the proposed control scheme, which is then validated also on a simulation basis. Simulations show the effectiveness of the proposed approach in managing fluctuations of network demand and renewable generation under realistic conditions.
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Chen, Yunghan, e 陳永翰. "Piezoelectric Energy Harvesting and Storage System". Thesis, 2012. http://ndltd.ncl.edu.tw/handle/59808201648171924808.
Texto completo da fonteResumo:
碩士大葉大學
機械與自動化工程學系
100
Nowadays, due to the energy shortages, people begin to find new energy sources to replace the existing ones. The ways of collecting energy sources in the environment play an important role in human life where many kinds of vibration energy exist. This green energy will gradually replace the traditional energy such as fossil energy, etc. Piezoelectric materials, which have the function of electromechanical energy conversion, can be applied to converting vibration energy into electrical energy. In this study, we have proposed a piezoelectric energy harvester, which is made of MEMS technology, can capture energy from airflow-induced vibration. It converts airflow energy into electrical energy by the piezoelectric conversion effect of the oscillation of PZT wafer. Besides, we also discuss the output electrical energy caused by the controlling factors in this article. The possibility that the electrical energy can be stored in the capacitor after rectification is verified finally. Experimental results show that the harvesting device produces an output power of about 13.07μW when the excitation pressure oscillates with an amplitude of 2.0kPa and a frequency of about 52.4Hz.
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Shih, Min-Cun, e 石閔存. "Development of Energy Storage System with Bidirectional Energy Control". Thesis, 2015. http://ndltd.ncl.edu.tw/handle/19501077351542254361.
Texto completo da fonteResumo:
碩士國立臺灣科技大學
電機工程系
103
The objective of this thesis was to develop an “Energy Storage System with Bidirectional Energy Control” based on conventional Digital Signal Processor. For household electricity, there will be some difference due to peak/light load or higher/lower electric rate, so the Energy Storage System in this thesis was applied in smart home to support Home Energy Management System to adjust and allocate power. The Energy Storage System includes bidirectional full bridge inverter, DC bus capacitor, bidirectional DC converter and battery. The feature of this system is to use the bidirectional power converter to adjust the charging/discharging time of the battery according to the energy plan scheduled by the Home Energy Management System to achieve instant home energy management and then enhance peak-shaving effect in order to reduce power usage and cost. The control strategy of the circuit is to use the bidirectional full bridge inverter with Predictive Current Control method to dispatch the current from the AC-grid. The operating mode can be divided into Grid-Connected mode and Power Factor Correction mode. While Grid-Connected mode enables the inverter to invert the power of the DC bus capacitor through the inverter to generate sinusoidal wave identical to the AC-grid, Power Factor Correction mode enables the inverter to rectify the power of the AC-grid through the inverter and feed it to the DC bus capacitor. On the other hand, the bidirectional DC converter is placed between the battery and the DC bus capacitor, and the operation mode can be set into Buck/Boost converter mode to regulate the voltage of the capacitor by using PI voltage regulation technique. The central core of the Energy Storage System is a high-efficiency Digital Signal Processor (TMS320F28335 produced by Texas Instruments.) The energy management and control strategies were accomplished by software in order to reduce the cost of hardware circuitry. Furthermore, this thesis has designed a 350W “Energy Storage System with Bidirectional Energy Control” and proved the feasibility of the thesis.
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Datta, Ujjwal. "Battery Energy Storage System for Renewable Energy Integrated Power System Stability Enhancement". Thesis, 2020. https://vuir.vu.edu.au/41874/.
Texto completo da fonteResumo:
With growing environmental concerns and sustainability movements, renewable energy source (RES) penetration is increasing and expected to have a steady growth in the coming years. Power systems have encountered several inherent technical challenges, resulting from either low inertia contribution by the increased RES or the displacement of fossil fuel generation systems within the network. The decreased system inertia and the decline in power reserve capacity are affecting the dynamic and transient stability performance of the power system adversely and this adverse impact will continue to increase due to further RES penetration in electric power systems.
In this context, this thesis contributes new knowledge to the modelling of droop controlled BESS for enhancing damping capability and transient stability of large-scale power networks with different level of RES penetration. The BESS with conventional Proportional Integral (PI), and two new PI-lead and lead-lag controlled BESS with coordinated charge control are given wider attention. In the initial stage, a wind farm is designed to perform frequency control in a microgrid. A sectional droop gain method is adopted for regulating doubly fed induction generation (DFIG) power output. It is observed that the proposed multi-gain droop control method demonstrates superior performance than the conventional approach. However, DFIG has a certain limit of providing under-frequency support as a result of inherent incapability of regulating incoming wind speed. Hence, a more reliable energy source is required to secure the stability of the system.
Realizing these facts, comprehensive simulation studies have been carried out to explore various RES penetration level and dynamic response capability of the system undergoing multiple contingencies. Simulation results demonstrate that generator control and system loading conditions have significant impact on damping capability in primary frequency control. However, results with active power regulated BESS exhibit its effectiveness in enhancing primary frequency controllability of the system regardless of generator control and system loading conditions in power grid as RES penetration increases. Furthermore, a new state of charge (SOC) adaptive charging strategy is proposed for recovering battery SOC to ensure BESS reliability against future contingencies. The new adaptive SOC strategy defines separate levels of SOC charging limit than that of the maximum SOC limit to ensure sufficient SOC excursion for over-frequency events.
In the next stage, a droop controlled BESS is modelled and investigated to control simultaneous voltage and frequency responses of the system by regulating its active and reactive power independently. The performance of BESS is compared with the state- of-the-art technology Static Compensator (STATCOM), while the system is exporting a large amount of power across the network under various contingency studies. It is shown via simulation studies that STATCOM fails to secure voltage and frequency stability of the system in the occurrence of a single or multiple adjacent faults. On the contrary, the incorporated BESS with active and reactive regulating capability remains successful in maintaining the stability of the power system. Also, lead-lag controlled BESS has demonstrated improved performance than PI and PI-lead controlled BESS.
In the final stage of research, the effectiveness of BESS in a charging station is explored to avoid transformer overloading, provide PV smoothing and to increase the charging capacity of the station. Simulation studies showed that BESS can effectively reduce transformer overloading and as a result it prolongs its lifespan and provide grid services when charging station has no load demand.
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Martinez, Ivan Curtis, e 馬依凡. "Utilizing Energy Storage System to Improve Power System Vulnerability". Thesis, 2012. http://ndltd.ncl.edu.tw/handle/31607641894693148123.
Texto completo da fonteResumo:
碩士國立中山大學
電機工程學系研究所
100
In this thesis, security measures and vulnerability mitigation are mainly addressed. How to improve the system vulnerability is one of the main issues for power system operation and planning. Recent research revealed that Energy Storage Systems (ESSs) have a great potential to be used to improve system vulnerability. A vulnerability assessment is proposed in this thesis to identify the impact factors in the power systems due to generation outage and line outage. A Bus Impact Severity (BIS) analysis is then proposed and used to find the vulnerable buses in the system. The buses with the larger BIS value defined in this thesis are the better locations for ESSs placement. Formulations for optimal locations and capacities of ESSs placement are derived and then solved by Genetic Algorithm (GA). Test results show that the proposed method can be used to find the optimal locations and capacities for ESSs for system vulnerability improvement.
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Lin, Keng-Hsien, e 林庚賢. "A study of flywheel energy storage system". Thesis, 2007. http://ndltd.ncl.edu.tw/handle/50025808224798349525.
Texto completo da fonteResumo:
碩士國立勤益科技大學
資訊與電能科技研究所
95
Hi-tech industry has become a necessary trend of industry development in Taiwan. However, despite of the research and development technology, the instability of power system will cause serious influence on both producing efficiency and amount of the Hi-tech industry. Therefore, supplied by stable power is a very important link to the basis of Hi-tech industry. For this idea, the study provides flywheel storage uninterruptible power supply. At first, we aimed at the flywheel energy storage system (FESS) and simulated the storage effect of FESS. Measure the features of recharge and discharge as the reference of control circuit. Then, according to the testing results, we can design a simulation circuit and test it to find out if the circuit can support the load stably when the power is interrupted. Realize the designed flywheel energy storage system and test its characteristic. Know from the test results, the output of this flywheel system is three-phrase AC variation power. So in this study, use power electronics techniques (pulse-width modulation, PWM) to have the system supply stable power. Compared to traditional batteries, this storage system doesn’t need high current and much time to recharge. In this study, improve the flywheel energy storage system and its equipment. Keep a longer power supply for industrial power consumption and lower all the costs and make the best economy efficiency.