The rapidly evolving Nordic Power System demands enhanced flexibility and robustness in electricity production. The traditional role of hydropower plants in regulating the grid frequency has been challenged by new criteria for dynamic stability, which some units struggle to meet due to their relatively poor dynamic performance. This study addresses this challenge by investigating the potential of integrating optimal energy storage systems with hydropower plants. This study aimed to develop a tool that could streamline the process of converting a traditional hydropower plant into a hybrid unit using an optimal energy storage system. The problem is complex and requires an innovative approach that combines electrical engineering expertise with cutting-edge machine-learning algorithms. A comprehensive hydropower plant model, including governor control and mechanical and hydraulic subsystems, was developed and integrated with an energy storage system model to form a hybrid unit. This model was validated using real power plant data. Three distinct XGBoost Regressor models were trained using data samples generated from the optimized hybrid unit. These models aim to predict power and energy requirements for an optimal energy storage solution, including an estimation of wear and tear reduction. The XGBoost Power Regressor achieved a prediction accuracy of 92 % and the XGBoost Energy Regressor demonstrated a 95 % accuracy. The XGBoost Movement Regressor, indicating wear and tear, boasted an accuracy greater than 99 %. The integration of energy storage systems can significantly mitigate wear and tear on a hydropower plant, with reductions of up to 85 % or more. The results indicate that integrating energy storage systems with hydropower units can substantially enhance the dynamic performance, reduce wear and tear and enable the plants to meet the demanding requirements of providing frequency regulation services in the Nordic Power System. The findings of this study culminate in a robust and user-friendly tool capable of accurately estimating optimal energy storage requirements for any hydropower plant tasked with meeting frequency regulation service demands. / Det nordiska kraftsystemet är under snabb förändring och skiftar alltmera till elproduktion med krav på ökad flexibilitet och tillförlitlighet. Vattenkraftverkens traditionella roll som källa till reglering och stabilisering av nätfrekvensen, utmanas nu av nya krav på dynamisk prestanda och stabilitet. På grund av sina relativt dåliga prestanda har vissa vattenkraftverk svårigheter att uppfylla dessa nya krav. Detta examensarbete behandlar denna utmaning genom att undersöka möjligheterna att integrera optimala energilagringssystem med vattenkraftverk. Syftet med arbetet var att utveckla ett verktyg som skulle kunna effektivisera processen för att omvandla ett traditionellt vattenkraftverk till ett hybridkraftverk med hjälp av ett optimalt energilagringssystem. Detta är ett komplext problem som kräver ett innovativt tillvägagångssätt som kombinerar elkraftteknik med avancerade algoritmer för maskininlärning. En omfattande modell utvecklades för att simulera ett vattenkraftverk med styrsystem, mekaniska och hydrauliska system. Denna kraftverksmodell integrerades med en modell för ett energilagringssystem för att tillsammans bilda en hybridenhet. Modellens validitet verifierades med hjälp av verkliga testdata. Med hjälp av data från simuleringar av den optimerade hybridenheten kunde tre XGBoost-regressionsmodeller skapas för att estimera både effekt och energibehov för ett optimalt energilagringssystem. Utöver detta kunde även en uppskattning av minskning av slitage presenteras. XGBoost Power Regressor uppnådde en träffsäkerhet på 92 % och XGBoost Energy Regressor uppvisade en träffsäkerhet på 95 %. XGBoost Movement Regressor, som indikerar slitage, hade en noggrannhet på högre än 99 %. Integrering med energilagringssystem kan avsevärt minska slitaget på ett vattenkraftverk, med minskningar på upp till 85 % eller mer. Resultaten visar att integrering av energilagringssystem och vattenkraftverk väsentligt kan förbättra den dynamiska prestandan, minska slitage och göra det möjligt för kraftverken att uppfylla kraven för att bidra med frekvensregleringstjänster i det nordiska kraftsystemet. Resultaten av denna studie kulminerar i ett robust och användarvänligt verktyg som kan uppskatta ett optimalt energilagringsystem för ett vattenkraftverk som ska uppfylla kraven för frekvensreglering.

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This study delves into the comparative operational effectiveness of non-coordinated, bottom-up, and top-down coordinated control models within Distributed Energy Storage Systems (DESS) and Electric Vehicle (EV) networks. Employing meticulous data analysis, this research evaluates power demand and supply dynamics within the infrastructure and buildings, aiming to optimize energy usage and storage. The analysis involves comprehensive steps: descriptive statistical breakdown, understanding energy patterns across buildings, and a comparative assessment of the control models. Visual representations and graphs aid in depicting energy patterns, emphasizing the distinctive characteristics and effectiveness of each control model. The findings reinforce the superiority of the top-down coordinated control model in managing supply-demand imbalances, echoing established literature.

<p dir="ltr">The need for reducing reliance on fossil fuels to meet ever-increasing energy demands and minimizing global climate change due to greenhouse gas emissions has led to an increase in investments in Variable Energy Resources (VREs), such as wind and solar. But due to the unreliable nature of VREs, an energy storage system must be coupled with it which drives up the investment cost.</p><p dir="ltr">Lithium-ion batteries are compact, modular, and have high cyclic efficiency, making them an ideal choice for energy storage systems. However, they are susceptible to capacity loss over the years, limiting the total life of the batteries to 15-18 years only, after which they must be safely discarded or recycled. Hence, designing a Battery Energy Storage System (BESS) should consider all aspects, such as battery life, investment cost, energy efficiency, etc.</p><p dir="ltr">Most of the available studies on cost and lifetime of BESS either consider a steady degradation rate over years, or do not account for it at all, they take constant charge/discharge cycles, and sometimes do not consider ambient temperature too. This may result in an error in estimation of the cost of energy storage. The location where the BESS is supposed to be installed can also impact its life, given that each location has its own power consumption trend and temperature profile. In this work, we attempt to simulate a BESS by considering the ambient temperature, degradation rate and energy usage. This will help in getting an insight of a more realistic estimate of levelized cost of storage and for estimating the thermal energy needed to keep them within a certain temperature range, so that they can last longer.</p>

A continuous increase in demands from the utility grid and traction applications have steered public attention toward the integration of energy storage (ES) and hybrid ES (HESS) solutions. Modern technologies are no longer limited to batteries, but can include supercapacitors (SC) and flywheel electromechanical ES well. However, insufficient control and algorithms to monitor these devices can result in a wide range of operational issues. A modern day control platform must have a deep understanding of the source. In this dissertation, specialized modular Energy Storage Management Controllers (ESMC) were developed to interface with a variety of ES devices. The EMSC provides the capability to individually monitor and control a wide range of different ES, enabling the extraction of an ES module within a series array to charge or conduct maintenance, while remaining storage can still function to serve a demand. Enhancements and testing of the ESMC are explored in not only interfacing of multiple ES and HESS, but also as a platform to improve management algorithms. There is an imperative need to provide a bridge between the depth of the electrochemical physics of the battery and the power engineering sector, a feat which was accomplished over the course of this work. First, the ESMC was tested on a lead acid battery array to verify its capabilities. Next, physics-based models of lead acid and lithium ion batteries lead to the improvement of both online battery management and established multiple metrics to assess their lifetime, or state of health. Three unique HESS were then tested and evaluated for different applications and purposes. First, a hybrid battery and SC HESS was designed and tested for shipboard power systems. Next, a lithium ion battery and SC HESS was utilized for an electric vehicle application, with the goal to reduce cycling on the battery. Finally, a lead acid battery and flywheel ES HESS was analyzed for how the inclusion of a battery can provide a dramatic improvement in the power quality versus flywheel ES alone.

La qualité de la puissance injectée au réseau électrique est une problématique importante pour le développement des énergies marines renouvelables, et en particulier de l'énergie des vagues, ou énergie houlomotrice. En effet la puissance produite par les systèmes houlomoteurs à entrainement direct est très fluctuante (fluctuations de l'ordre de la seconde) à cause de la nature oscillante de la ressource. Afin d'étudier l'impact de l'intégration des ces systèmes sur les réseaux électriques, un modèle permettant de représenter la chaîne depuis la vague jusqu'au réseau électrique a été développé. Les simulations effectuées à l'aide de ce modèle pour différents types de réseau électrique et différents états de mer ont montré que la mise en place de solutions pour améliorer la qualité de la puissance produite était nécessaire. Ainsi l'effet du regroupement et de la dispersion spatiale des systèmes houlomoteurs sur la qualité de la puissance a été étudiée. L'insertion d'un système de stockage dans la chaîne wave-to-wire afin de lisser la puissance a aussi été considérée. Enfin, une partie du modèle a pu être validée à l'aide d'un banc de test Hardware-in-the-loop comprenant un banc moteur, des armoires de puissance pour émuler électronique de puissance et le réseau électrique et un module de supercondensateurs. / Power quality is an important issue for the development of marine renewable energies, in particular wave energy. Due to the oscillatory nature of the oceans waves, the wave energy converters output power profile can present fluctuations in the range of seconds. The impact of these devices on the electric grid therefore needs to be investigated for wave farms to be connected to the grid. In order to emulate an operating direct drive wave energy converter, study power quality improvement and test different control strategies, a wave-to-wiremodel has been developed.Simulations carried out with this model for different grid strengths and different levels of sea-state showed that it is necessary to foster solutions to improve power quality. Thus, the wave energy converters aggregating and dispersion effects on power quality have been investigated. As it does not seem sufficient to meet the grid codes requirements, another solution have been considered, consisting of the insertion of an energy storage system into the chain. Finally, a part of the model has been validated using a hardware-in-the-Loop test bench including a motorbench, power modules to emulate the grid and power electronic's control and super capacitors module.

A utilização de conversores multiníveis tem sido uma importante alternativa para aplicações de alta potência e média tensão, graças aos altos níveis de potência alcançáveis por estas estruturas. Recentemente, esta topologia de conversores foi aplicada em sistemas com fontes alternativas para alimentar um sistema de geração distribuída, nos quais diferentes fontes de energia eram utilizadas. Com base nas características dos conversores multinível e sua potencial aplicabilidade em sistemas de geração distribuída, este trabalho tem como objetivo construir um sistema multinível conectado a rede de distribuição para utilização de fontes alternativas de energia como fontes primárias. Considerando que a energia fornecida pelas fontes alternativas pode sofrer variações, propõe-se a integração de sistemas armazenadores de energia, como capacitores, ao sistema multinível. Por isso, este trabalho desenvolve uma estratégia de controle para máxima transferência de potência ativa entregue à rede a fim de obter um fluxo ótimo. A topologia multinível deste trabalho possui em sua configuração dois módulos inversores conectados em série. Neste caso, é possível que pelo menos um desses inversores funcione com uma modulação em baixa frequência processando a maior parcela de potência. Assim, duas estratégias de controle modulação de fase e modulação de amplitude para a transferência de potência realizada pelo inversor de baixa frequência são analisadas. As vantagens e desvantagens de cada um dos métodos são expostas e então a estratégia mais adequada, no caso a modulação de amplitude, é utilizada na operação do conversor multinível. Além disso, são apresentados a modelagem das plantas e o projeto dos controladores de cada um dos módulos inversores. Por fim, a validação da proposta é feita através dos resultados de simulações e experimentais que mostram a capacidade do sistema de geração em transferir potência constante para a rede de distribuição e manter a corrente quase sem distorções em fase com a tensão. / The utilization of multilevel converters has been an important alternative for medium voltage applications with high power and power quality demand, thanks to the high power levels achievable for this kind of structure. Recently, this converter topology was proposed as a new possibility in renewable energy source applications, mainly in system delivering power to the grid, where different renewable energy resources may be used. Based on the characteristics of multilevel converters, and their potential applicability in distributed generation systems, this study aims to build a multilevel system that could be powered by renewable energy sources as primary sources and then connect them to a distribution grid. However, considering the energy produced by alternative sources can vary, it is analyzed the integration of a storage energy system in this multilevel topology. Taking into account this ends, the main concern of this study is related to the development of a control strategy to maximize the active power transferred to the grid. The multilevel topology employed in this study has two H-bridge inverter modules connected in series forming a cascaded configuration. Therefore, it is possible that at least one of these inverters, operating with a low frequency of modulation, process the majority of power with lower amount of losses. On this way, two control strategies for power transfer are analyzed. The advantages and disadvantages of each method are presented, and the most appropriated strategy is used in the operation of the multilevel converter system. In addition, it has been presented the design criteria for each controller and finally the validation of the proposed approach is done by mains of simulations and experimental results which show the ability of the converter to transfer constant active power to the grid and keep the grid current in phase with the grid voltage.

Des solutions innovantes doivent être développées pour envisager l’avenir des systèmes électriques face à un nombre grandissant de contraintes. En particulier, le stockage d’énergie est pressenti comme un soutien indispensable à l’essor massif dans les réseaux de distribution de sources de production exploitant les énergies renouvelables. Les présents travaux visent à apporter des éléments de réflexion sur cette option technique qui arrive à maturité et suscite l’intérêt. Dans un premier temps, des méthodes d’étude sont proposées pour cerner le potentiel et les opportunités du stockage distribué. Une grille de caractérisation des technologies est introduite et sa mise en œuvre souligne des performances intéressantes à des coûts qui, cependant, demeurent élevés. Pour rendre leur utilisation réaliste, la valeur de ces dispositifs pour les systèmes électriques est donc critique. Nous l’analysons en deux étapes : une classification de leurs services pour les différents acteurs en présence est définie avant d’aborder la mutualisation de fonctions, requise pour favoriser l’atteinte d’une rentabilité, via une approche originale. Cette démarche aboutit à l’identification de configurations porteuses qui méritent des études plus poussées. Pour ce faire, un modèle général de comportement des unités de stockage est développé dans un second temps. Interfacé à un logiciel de simulation dynamique des réseaux, il permet d’évaluer l’utilisation de telles installations pour diverses offres de services. Ces outils sont appliqués et validés expérimentalement sur la caractérisation d’une réserve impulsionnelle fournie par le stockage pour réduire les délestages dans les systèmes insulaires / Innovative solutions must be developed to make future power systems able to overcome a growing number of challenges. In particular, energy storage is thought to be the missing link that will help enable the massive integration of renewable sources in distribution grids. The present research work aims to investigate this new technical option, which has reached maturity and is currently attracting increasing attention. In the first part of the dissertation, general methods to assess the potential and opportunities of distributed energy storage are presented. A framework for characterizing storage technologies is defined and its use highlights interesting performances but high costs. That is why the benefits of such devices for power systems are crucial to their development. The study of this point is carried out in two phases: their applications for various stakeholders of liberalized power systems are first classified and precisely defined; the aggregation of some of these services to increase the profitability of energy storage is then contemplated using a new method. This approach leads to the identification of high-value configurations that deserve further exploration. To this end, a scalable, flexible model of distributed energy storage systems is proposed in the second part of the dissertation. Its implementation in a dynamic simulation software allows the study of advanced storage service packs in power systems. The possibilities offered by these tools are illustrated and experimentally validated on a case study: the provision of a fast frequency control reserve by distributed storage to reduce the use of automatic load-shedding in isolated power systems is analyzed

Orientador: José Roberto Sanches Mantovani / Resumo: O planejamento de curto prazo é uma estratégia de tomada de decisão que visa assegurar o desempenho adequado de um sistema de distribuição de energia elétrica e fornecer um produto de alta qualidade aos usuários finais. Este processo considera ações tradicionais para um controle efetivo no fluxo de potência reativa, fator de potência e magnitude de tensão nas barras do sistema. Nos últimos anos, este tipo de planejamento enfrenta-se com significativos desafios devido à integração de novas tecnologias e a filosofia de operação das redes de distribuição de média tensão. Desta forma, o desenvolvimento de algoritmos e ferramentas computacionais sofisticadas são necessárias para contornar essas complexidades. Nessa perspectiva, neste trabalho apresenta-se uma estratégia para a solução do problema de planejamento de curto prazo para redes de distribuição. Em que, a integração de unidades de geração distribuída e sistemas de armazenamento de energia elétrica é considerada simultaneamente com as ações tradicionais de planejamento para melhorar a eficiência do sistema. Diferentes alternativas de investimento, tais como a localização e dimensionamento de bancos de capacitores, unidades de armazenamento de energia e unidades de geração baseadas em energia fotovoltaica e eólica, seleção e substituição de condutores dos circuitos sobrecarregados e alocação de reguladores de tensão são consideradas como variáveis de decisão no problema de otimização. Adicionalmente, na formulação deste pro... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Short-term planning is a decision-making strategy that aims to enhance proper electric distribution network performance and provide high-quality service to consumers. This process considers traditional planning actions to effectively control the reactive power flow, power factor, and the voltage profile of the network. In the last years, this type of distribution network planning has faced important challenges due to the integration of modern technologies and operating aspects of medium-voltage distribution networks. In this regard, development of sophisticated algorithms and computational tools are necessary to cope with these complexities. In this perspective, a strategy to determine the solution of the short-term planning problem for distribution networks is presented in this work, where, integration of distributed generation units and electric energy storage systems are considered simultaneously with traditional planning actions to improve the network performance. Several investment alternatives such as siting and sizing of capacitors banks, energy storage systems, photovoltaic- and wind- based generation units, conductor replacement of overloaded circuits, and voltage regulators allocation are considered as decision variables in the optimization problem. Additionally, environmental aspects at distribution level are duly addressed via Cap and Trade mechanism. Inherently, this optimization problem is represented by a non-convex mixed integer nonlinear programming problem. ... (Complete abstract click electronic access below) / Doutor