Battery energy storage system (BESS) is promising to be implemented in residential applications for supporting PV integration, load shifting, and backup power purposes. For this application, 48V second-life battery draws more and more attentions for their cost-effectiveness, safe voltage level, reliability, and potential large market. This thesis proposes the comprehensive control and design of an isolated battery-driven grid interface (IBDGI) with the dual-active-bridge (DAB) converter for residential applications with 48V battery pack. The three-phase DAB converter is a promising candidate as the front-end DC/DC converter in the two-stage IBDGI due to its high efficiency, high power density, and low capacitance requirement. An effective design strategy for the three-phase DAB converter is proposed based on the zero-voltage-switching (ZVS) zone and back-ow power to achieve high efficiency for a wide operating voltage range and different load conditions. Based on the power loss model, an easily-implemented variable switching frequency operating method is proposed to further increase the efficiency at light load conditions. The dead-time effect is observed in the three-phase DAB converter. To avoid the dead-time effect and better understand the phenomena, a comprehensive analysis is proposed. All the cases of the dead-time effect in the three-phase DAB converter are analyzed in terms of the buck, boost, and matching states. The expressions of the transmission power, constraint conditions, and key time of the dead-time effect are derived for each state. The operation waveforms of the dead-time effect are also presented. The hybrid capacitor bank composed by the LC resonant lter with electrolytic capacitor and lm capacitor is utilized for the DC bus of the IBGDI. The electrolytic capacitors work as passive decoupling purpose while the lm capacitor is responsible for high switching harmonic ltering. Moreover, a current sharing method between the hybrid capacitor bank is proposed to extend the electrolytic capacitor's life. The LCL single-phase inverter is applied for the downstream of the IBDGI. A step-by-step design procedure of the LCL lter with passive damping is proposed for the 120V/240V dual grid-tied and standalone modes. The PR controllers are also designed for the LCL inverter for standalone and grid-tied modes. At the system level, a novel second harmonic current (SHC) reduction strategy is proposed for the IBDGI with the three-phase DAB converter by adding a load current feedforward (LCFF) path to the DAB voltage closed-loop controller. This method will suppress the SHC without modi cations of the original controller's bandwidth, which make it easy to be implemented. The small-signal model of the three-phase DAB converter is provided and veri ed by the step response. The parameter sensitivity analysis for the LCFF method is proposed to show that the SHC is well suppressed within ±20% parameter error. The proposed converter and control methods are veri ed by simulation and experimental results. / Thesis / Doctor of Philosophy (PhD)

A hybrid ac/dc microgrid is a more complex but practical network that combines the advantages of an AC and a DC system. The main advantage of this network is that it connects both alternating current and direct current networks via an interlinking converter (IC) to form a unified distribution grid. The hybrid microgrid (HMG) will enable the direct integration of both alternating current (AC) and direct current (DC) distributed generators (DGs), energy storage systems (ESS), and alternating current and direct current (DC) loads into the grid. The alternating current and direct current sources, loads, and ESS are separated and connected to their respective subgrids primarily to reduce power conversion and thus increase overall system efficiency. As a result, the HMG architecture improves power quality and system reliability. Planning a hybrid microgrid entails estimating the capacities of DGs while taking technical, economic, and environmental factors into account. The hybrid ac-dc microgrid is regarded as the distribution network of the future, as it will benefit from both ac and dc microgrids. This thesis presents a general architecture of a hybrid ac-dc microgrid, which includes both planning and design. The goal of the Hybrid ac-dc microgrid planning problem is to maximise social welfare while minimising total planning costs such as investment, maintenance, and operation costs. This configuration will assist Hybrid microgrid planners in estimating planning costs while allowing them to consider any type of load ac/dc and DER type. Finally, this thesis identifies the research questions and proposes a future research plan.

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.

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.

Le « Lithium-Ion Capacitor » (LiC) est un supercondensateur hybride dont les caractéristiques peuvent être placées entre un condensateur à double couche électrique (supercondensateur) et une batterie lithium-ion. Il possède des densités d’énergie et de puissance intermédiaires grâce à sa composition hybride à base d'une électrode positive en charbon actif identique à celle d’un supercondensateur et d'une électrode négative en carbone pré-lithié identique à celle d’une batterie lithium-ion. L'objectif de cette thèse est d'étudier le vieillissement des LiC industrialisés aussi bien dans le cadre d’un vieillissement en stockage (calendaire) qu’en utilisation (cyclage). Un de leur spécificité principale concerne l’évolution particulière de leur capacité en fonction de la tension à leurs bornes (C(V)). Le premier type de vieillissement qu’est le vieillissement calendaire permet de représenter le comportement des LiC lorsqu’ils sont stocker avant utilisation ou lorsqu’ils sont en veille. La dégradation de leurs paramètres liée au vieillissement, est alors essentiellement influencée par leur tension et la température. Des essais de vieillissement à trois tensions caractéristiques et deux températures différentes sont étudiés. L’évolution des impédances des cellules a été suivie tout au long du vieillissement afin d’identifier un modèle électrique de suivi du vieillissement dont les paramètres sont liés aux phénomènes électrochimiques. Par ces essais, la meilleure tension de stockage des LiC, permettant la prolongation de leur durée de vie a été mise en évidence. Par ailleurs, des mécanismes de vieillissement différents d’une tension caractéristique à l’autre sont révélés et soulignent la spécificité de fonctionnement des LiC. Ces résultats ont été confirmés par des analyses post-mortem. Le second type de vieillissement étudié est le vieillissement par cyclage qui prend en compte l'impact du courant sur la durée de vie des LiC. Le choix des profils de courant de cyclage a été effectué en considérant le principe de fonctionnement électrochimique des LiC. Les évolutions des impédances et des courbes C(V) des cellules sont comparées et interprétées. Les mécanismes de vieillissement prenant naissance lors du cyclage continu sont abordés. Ils dépendent de la fenêtre de potentiel sur laquelle les LiC fonctionnent pendant leur utilisation. La fenêtre de tension optimale qui assure une longue durée de vie des LiC est aussi mise en évidence / Lithium-Ion Capacitors (LiCs) are the new emerging technology of hybrid supercapacitors that combines the advantages of conventional supercapacitors and lithium-ion batteries. They provide intermediate energy and power densities due to their hybrid composition based on a positive electrode made of activated carbon similar to that of supercapacitors and a negative electrode made of pre-lithiated carbon similar to that of lithium-ion batteries. The aim of this thesis is to study the aging of commercial LiCs using two accelerated aging procedures: calendar aging and cycle aging. One of their main particularities concerns the nonlinear capacitance evolution with respect to their voltage (C(V) curve). The first accelerated aging test is related to the calendar life of LiCs that represents their behavior independently of their usage. The degradation of their parameters due to aging is mainly affected by the voltage and the temperature only. These tests were applied to several cells at three different voltage values and two temperatures. The evolution of their impedances were followed during the whole aging period in order to identify an electrical model that can accurately describe the progress of aging and that possesses electrochemically meaningful parameters. The best voltage value that ensures the extension of the lifetime of LiCs was identified using the results of these tests. In addition, aging mechanisms that extremely depend on the applied voltage value were identified. They highlight the particularity of the functioning of LiCs. These results were confirmed using post-mortem analyses. The second accelerated aging test is the cycle aging that assesses the impact of the current on the life cycle of LiCs. The choice of current profiles was based on the electrochemical operating principle of LiCs. The evolution of the impedances and the C(V) curves of LiCs were compared and analyzed. Aging mechanisms produced during cycle aging were also evaluated. They depend on the voltage range in which the LiC operates. The optimal voltage window that guarantees a long lifetime of LiCs was highlighted

Dentre as diversas fontes de energia renovável que existem atualmente, a energia eólica é a que tem apresentado o maior crescimento nos Sistemas Elétricos de Potência (SEPs). A flutuação de potência da geração eólica, no entanto, tem causado grandes desafios no que diz respeito à Qualidade da Energia Elétrica (QEE) e à operação do SEP. O grande progresso dos Sistemas de Armazenamento de Energia (SAEs), aliado à crescente inserção de geração eólica nos SEPs, tem promovido grande interesse na utilização dos SAEs junto aos aerogeradores. Este trabalho apresenta a utilização de um SAE, conectado ao elo CC do conversor back-to-back do aerogerador, e uma técnica de controle baseada na lógica fuzzy para suavizar as variações da potência de curto prazo da geração eólica. A técnica de controle proposta também é utilizada para gerenciar o Estado de Carga (SOC) do SAE para evitar a condição sobrecarregada e totalmente descarregada. O controle fuzzy é testado e comparado com uma técnica de controle convencional e também com a topologia típica do aerogerador, onde não é utilizado o SAE. As técnicas são avaliadas e comparadas com base em diferentes indicadores numéricos da qualidade da suavização. Um simulador digital em tempo real (RTDSR) é utilizado para realizar as simulações, onde é considerado um aerogerador de 2 MW, um supercapacitor e uma microrrede baseada no benchmark do CIGRÉ de média tensão. Os resultados mostraram que as técnicas de controle do supercapacitor possibilitaram uma adequada suavização de potência da geração eólica e puderam contribuir para a QEE e a operação da microrrede. A técnica inteligente baseada no controlador fuzzy mostrou resultados superiores à técnica convencional e, portanto, apresentou grande potencial para a aplicação. / Among several renewable energy sources existing nowadays, wind energy has presented the largest growth in power systems. The wind power fluctuations, however, has brought great challenges concerning Power Quality (PQ) and power system operation. The great progress of Energy Storage Systems (ESSs), together with the increasing penetration of wind power worldwide, has lead to a great interest in the use of ESS in wind energy. This study presents the application of a ESS, connected to the DC link of the backto- back converter of the wind turbine, and a control technique based on fuzzy logic to smooth out the short-term wind power fluctuations. The proposed control technique is also used to manage the State of Charge (SOC) of the ESS to avoid the overcharged and undercharged states. The fuzzy control is tested and compared with a conventional control technique and also with the typical wind turbine topology, where the ESS is not used. The techniques are evaluated and compared based on different quantitative indicators that represent the quality of the power smoothing. Simulations are carried out in the Real-Time Digital Simulator (RTDSR), where a 2 MW wind turbine, a supercapacitor and a microgrid system based on the CIGRÉ medium voltage benchmark are considered. The results have shown that the control techniques of the supercapacitor permitted a suitable smoothing of the fluctuating wind power and contributed to the microgrid PQ and operation. The intelligent control technique based on the fuzzy logic has shown superior performance compared to the conventional technique and, therefore, presented great potential for application.

L’objet de cette thèse est l’intégration des parcs photovoltaïques intelligents au marché de l’électricité dans un environnement de libre concurrence. Les centrales photovoltaïques intelligentes sont celles qu’incluent systèmes de stockage pour réduire sa variabilité et en plus fournir à l’ensemble une plus grande contrôlabilité. Ces objectives techniques sont obtenues grâce à la capacité bidirectionnelle d’échange et stockage d’énergie qu’apportent les systèmes de stockage, dans ce cas, les batteries. Pour obtenir la rentabilité maximale des systèmes de stockage, le dimensionnement doit être optimisé en même temps que la stratégie de gestion avec laquelle le système de stockage est commandé. Dans cette thèse, une fois la technologie de stockage plus adapté à l’application photovoltaïque est sélectionnée, à savoir la technologie de lithium-ion, une participation innovatrice de part des parcs photovoltaïques intelligents dans le marché de l’électricité est proposée qui optimise à la fois le dimensionnement et la stratégie de gestion d’une manière simultanée. Ce processus d'optimisation ainsi que la participation au marché de l'électricité a été appliquée dans un cas d’étude réel, ce qui confirme que cette procédure permet de maximiser la rentabilité économique de ce type de production. / The present PhD deals with the integration of intelligent photovoltaic (IPV) power plants in the electricity markets in an environment subject to free competition. The IPV power plants are those that include energy storage systems to reduce the variability and to provide the entire group a controllability increase. These technical objectives are obtained thanks to the bidirectional exchanging and storing capability that the storage system contributes to, in this case, battery energy storage system (BESS). In order to obtain the maximum profitability of the BESS, the sizing must be optimized together with the control strategy that the BESS will be operated with. In the present PhD, once the most performing battery energy storage technology has been selected, the lithium-ion technology, an innovative IPV power plant electricity market participation process is proposed which optimizes both the sizing and the energy management strategy in the same optimization step. This optimization process together with the electricity market participation has been applied in a real case study, confirming that this procedure permits to maximize the economic profitability of this type of generation.

Distributed power generation through renewable sources of energy has the potential of meeting the challenge of providing electricity access to the off-grid population, estimated to be around 1.2 billion residing across the globe with 300 million in India, in a sustainable way. Technological solutions developed around these energy challenges often involve thermal systems that convert heat available from sources like solar, biomass, geothermal or unused industrial processes into electricity. Conventional steam based thermodynamic cycle at distributed scale (< 1 MWe) suffers from low efficiency driving scientific research to develop new, scalable, efficient and economically viable power cycles. This PhD work conducts one such study which provides a database of thermal power blocks optimized for the lowest initial investment cost to developers of distributed power plants. The work is divided in two steps; a) feasibility study of various thermodynamic cycles for distributed power generation covering different operating temperature regimes and b) perform their detailed thermo-economic modelling for the heat sources mentioned above. Thermodynamic cycles are classified into three temperature domains namely, low (< 450 K), medium (< 600 K) and high (< 1000 K) T cycles. Any fluid whose triple point temperature is below the typical ambient temperatures is a potential working fluid in the power cycle. Most of the organic and the inorganic fluids satisfy this criterion and can be perceived as potential power cycle fluids. The general notion is that organic fluids are more suited for low or medium temperature cycles whereas inorganic fluids for high temperature ones. Organic fluids can further be classified into hydrofluorocarbon and hydrocarbon. While the former has high global warming potential (GWP), the latter is flammable in nature. Their mixture in certain compositions is found to obviate both the demerits and perform equally well on thermodynamic scales for low T cycles. On the similar lines, mixture of HCs and inorganic fluids, such as propane+CO2 and isopentane+CO2 are found to be more appropriate for medium T applications if the issues like pinch temperature in the regenerator arising due to temperature glide are taken care of. In the high temperature domain, high efficiency Brayton cycle (supercritical CO2) and transcritical condensing cycles are studied with the latter being 2 % more efficient than the former. However, application of the condensing cycle is limited to low temperature ambient locations owing to low critical temperature of CO2 (304 K). In the same cycle configuration, mixture of CO2 and propane (52 and 48%) with a critical temperature of ~ 320 K is observed to retain the thermodynamic performance with the increased heat rejection temperature matched to the tropical ambient conditions. However, these cycles are plagued by the high operating pressures (~300 bar) calling for high temperature steel making the power block uneconomical. In this regard, the advanced CO2 cycles are developed wherein the optimum operating pressures are limited to 150 bar with an increased cycle efficiency of 6 % over the S-CO2 cycle. Feasibility study carried out on these cycles in the Indian context indicates the low and medium T cycles to be better suited for distributed power generation over the high T cycles. In the second part of work, a comprehensive study is performed to optimize the low and the medium T cycles on a thermo-economic basis for the minimum specific investment cost ($/We). Such a study involves development of component level models which are then integrated to form the system of interest, thus, following a bottom-up approach. A major emphasis is given on the development of scroll expander and low cost pebble bed thermal energy storage system that are the reported in the literature as the areas with high uncertainties while connecting them to the system. Subsequently, the key design parameters influencing the specific cost of power from an air-cooled ORC are identified and used to formulate a 7-dimensional space to search for the minimum costs for applications with a) geothermal/waste or biogas heat sources and b) solar ORCs. Corresponding maps of operating parameters are generated to facilitate distributed power engineers in the design of economic systems within constraints such as available heat source temperatures, maximum expander inlet pressures imposed, etc. Further, the effect of power scaling on these specific costs is evaluated for ORC capacities between 5 and 500 kWe.

The energy demand is steadily increasing, and the electricity sector is undergoing a severe change in this decade. The primary drivers, such as the need to decarbonize the power industry and megatrends for more distributed and renewable systems, are resulting in revolutionary changes in our lifestyle and industry. The power grid cannot be easily or quickly be upgraded, as investment decisions, construction approvals, and payback time are the main factors to consider. Therefore, new technology, energy storage, tariff reform, and new business models are rapidly changing and challenging the conventional industry. In recent times, industrial peak shaving application has sparked an increased interest in battery energy storage system (BESS).  This work investigated BESS’s potential from peak shaving and Time-of-use (TOU) applications for a Culture-house in Skellefteå. Available literature provides the knowledge of various BESS applications, tariff systems, and how battery degradation functions. The predicted electrical load demand of the culture-house for 2019 is obtained from a consultant company Incoord. The linear optimization was implemented in MATLAB using optimproblem function to perform peak shaving and time-of-use application for the Culture-hose BESS. A cost-optimal charging/discharging strategy was derived through an optimization algorithm by analyzing the culture-house electrical demand and Skellefteå Kraft billing system. The decisional variable decides when to charge/discharge the battery for minimum battery degradation and electricity purchase charges from the grid.   Techno-economic viability is analyzed from BESS investment cost, peak-power tariff, battery lifespan, and batter aging perspective. Results indicate that the current BESS price and peak-power tariff of Skellefteå Kraft are not suitable for peak shaving. Electricity bill saving is too low to consider TOU application due to high battery degradation. However, combining peak shaving &amp; TOU does generate more profit annually due to additional savings from the electricity bill. However, including TOU also leads to higher battery degradation, making it not currently a viable application. A future scenario suggests a decrease in investment cost, resulting in a shorter payback period.  The case study also analyses the potential in the second-life battery, where they are purchased at 80 % State of Health (SoH) for peak shaving application. Second-life batteries are assumed to last until 70 % or 60 % before End of Life (EOL). The benefit-cost ratio indicates that second-life batteries are an attractive investment if batteries can perform until 60% end of life, it would be an excellent investment from an economic and sustainability perspective. Future work suggests integrating more BESS applications into the model to make BESS an economically viable project.

Dans les applications de puissance, les systèmes de stockage d'énergie électrique tels que les supercondensateurs sont fortement sollicités. Compte tenu des limitations existantes lors de l'utilisation d'un seul composant, un système de stockage d'énergie électrique (module) est constitué d'une association d'éléments (cellules) permettant de s'adapter aux besoins de l'application visée. Afin d'assurer la sécurité de l'équipement et de son utilisateur, un système de gestion d'énergie, qui a pour rôle de surveiller et de contrôler continuellement les cellules, est associé au module de stockage. Le but des travaux de thèse est l'amélioration de la durée de vie des systèmes de stockage d'énergie. Cet objectif est réalisé grâce au contrôle des circuits d'équilibrage, éléments du système de gestion d'énergie, et déjà présents sur ces modules de stockage. Différentes méthodes de contrôle sont donc présentées, analysées et comparées afin d'évaluer l'état de santé des supercondensateurs surveillés. Une nouvelle approche d'équilibrage se basant sur le niveau de dégradation estimée est exposée. Elle permet d'équilibrer les vitesses de vieillissement des cellules et ainsi de prolonger la durée de vie de l'ensemble du système. Certains principes des résultats obtenus sont transposables aux batteries / Energy storage system such as supercapacitors are widely used in high power applications. However, due to single cell voltage limitation, an energy storage system (module) is often employed. It contains a chain structure of identical elements and ensures voltage adaptation to the corresponding application requirements. Energy management systems are associated to energy storage systems in order to assure user and equipment security. Their main role is to monitor and control energy storage systems elements continuously. The work presented aims to enhance the lifetime of energy storage systems. It relies on establishing balancing circuits on the terminals of the storage system elements. These control circuits are energy management system devices. Thus, various control approaches are discussed, analyzed and compared. They aim to estimate the supercapacitor's state of health. In addition, a new approach of balancing circuits is proposed. It is based on estimating the level of degradation of the elements. Thus, It allows aging speed equalization between module elements and storage system lifetime maximization. Some main results of the work could be generalized to batteries