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Dimensionamento e Análise de um Sistema de Armazenamento em Baterias Integrado numa Central Fotovoltaica
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O presente trabalho teve como principal objetivo analisar a viabilidade técnica da integração de um sistema de armazenamento em baterias (BESS) numa central fotovoltaica de grande escala, considerando as condições reais de operação, os requisitos técnicos da rede e as limitações inerentes à tecnologia. Inicialmente, foi caracterizada a central fotovoltaica em estudo, avaliando-se as suas perdas, curvas de produção e limitações de injeção na rede. Os resultados demonstraram que, apesar da elevada eficiência global do sistema, existem perdas relevantes associadas a fatores como temperatura, sombreamento, resistências óhmicas e rendimento dos inversores, que condicionam a energia efetivamente injetada. Posteriormente, foi realizado o dimensionamento do sistema BESS, com base numa metodologia conservadora assente no critério de fim de vida útil (EOL). Este critério assegura que, mesmo após 20 anos de operação e contabilizando a degradação natural das baterias, o sistema é capaz de garantir a injeção de 100 MWh de energia excedente da central fotovoltaica. Para tal, verificou-se a necessidade de sobredimensionar a capacidade inicial em aproximadamente 138%, garantindo margens de segurança ao longo da sua vida útil. As simulações realizadas indicaram que o BESS apenas necessitará de operar próximo de 100% de depth of discharge (DOD) em situações excecionais, particularmente durante o verão, quando a produção fotovoltaica atinge níveis elevados. Nesses cenários, a operação em DOD máximo garante a plena utilização da energia excedente disponível. Foi também analisada a evolução do state of health (SOH) das baterias ao longo do tempo, com base em dados fornecidos pelo fabricante. Estimou-se uma degradação acumulada de cerca de 27,4% ao fim de 20 anos, conduzindo a um SOH final de 72,6%. Estes valores confirmam a necessidade de adotar o critério EOL como base de dimensionamento, permitindo manter a
fiabilidade e o cumprimento das exigências da rede durante todo o ciclo de vida do projeto. Embora este estudo se tenha focado essencialmente na vertente técnica, torna-se evidente que existem implicações económicas relevantes. O sobredimensionamento do sistema conduz a custos adicionais significativos, sobretudo em períodos de baixa produção renovável, em que a utilização efetiva do BESS é reduzida. Assim, seria pertinente em trabalhos futuros integrar uma
análise custo-benefício detalhada, avaliando a viabilidade económica e possíveis estratégias de otimização, como a operação multi-serviços (arbitragem de energia, regulação de frequência e serviços de reserva). Em síntese, conclui-se que a implementação de um BESS numa central fotovoltaica constitui uma solução técnica viável e alinhada com as necessidades do Sistema Elétrico Nacional, contribuindo para a estabilidade da rede e para a maximização do aproveitamento da energia renovável. O estudo reforça ainda a importância do correto dimensionamento e planeamento a longo prazo, garantindo a sustentabilidade e a fiabilidade das soluções de armazenamento num contexto de transição energética.
The main objective of this work was to analyze the technical feasibility of integrating a Battery Energy Storage System (BESS) into a large-scale photovoltaic power plant, considering real operating conditions, grid technical requirements, and the inherent limitations of the technology. Initially, the photovoltaic plant under study was characterized by assessing its losses, production curves, and grid injection constraints. The results showed that, despite the high overall efficiency of the system, there are relevant losses associated with factors such as temperature, shading, ohmic resistances, and inverter efficiency, which directly affect the energy effectively injected into the grid. Subsequently, the BESS was dimensioned using a conservative methodology based on the endof-life (EOL) criterion. This approach ensures that, even after 20 years of operation and accounting for the natural degradation of the batteries, the system can guarantee the injection of 100 MWh of excess energy from the photovoltaic plant. To achieve this, it was necessary to oversize the initial capacity by approximately 138%, thus ensuring safety margins throughout its lifetime. The simulations carried out indicated that the BESS will only need to operate close to 100% depth of discharge (DOD) in exceptional situations, particularly during summer, when photovoltaic production reaches high levels. In these scenarios, operation at maximum DOD guarantees the full utilization of the available excess energy. The evolution of the batteries’ state of health (SOH) over time was also analyzed, based on data provided by the manufacturer. An accumulated degradation of about 27.4% was estimated at the end of 20 years, resulting in a final SOH of 72.6%. These values confirm the need to adopt the EOL criterion as the basis for sizing, allowing the system to maintain reliability and compliance with grid requirements throughout the entire project lifetime. Although this study has focused mainly on the technical aspects, there are significant economic implications. The oversizing of the system leads to considerable additional costs, especially during periods of low renewable production, when the effective utilization of the BESS is reduced. Therefore, it would be pertinent in future work to integrate a detailed cost-benefit analysis, evaluating economic feasibility and possible optimization strategies, such as multiservice operation (energy arbitrage, frequency regulation, and reserve services). In summary, it is concluded that the implementation of a BESS in a photovoltaic power plant is a technically feasible solution, aligned with the needs of the National Electric System, contributing to grid stability and to the maximization of renewable energy utilization. The study also reinforces the importance of proper sizing and long-term planning, ensuring the sustainability and reliability of storage solutions in the context of the energy transition.
The main objective of this work was to analyze the technical feasibility of integrating a Battery Energy Storage System (BESS) into a large-scale photovoltaic power plant, considering real operating conditions, grid technical requirements, and the inherent limitations of the technology. Initially, the photovoltaic plant under study was characterized by assessing its losses, production curves, and grid injection constraints. The results showed that, despite the high overall efficiency of the system, there are relevant losses associated with factors such as temperature, shading, ohmic resistances, and inverter efficiency, which directly affect the energy effectively injected into the grid. Subsequently, the BESS was dimensioned using a conservative methodology based on the endof-life (EOL) criterion. This approach ensures that, even after 20 years of operation and accounting for the natural degradation of the batteries, the system can guarantee the injection of 100 MWh of excess energy from the photovoltaic plant. To achieve this, it was necessary to oversize the initial capacity by approximately 138%, thus ensuring safety margins throughout its lifetime. The simulations carried out indicated that the BESS will only need to operate close to 100% depth of discharge (DOD) in exceptional situations, particularly during summer, when photovoltaic production reaches high levels. In these scenarios, operation at maximum DOD guarantees the full utilization of the available excess energy. The evolution of the batteries’ state of health (SOH) over time was also analyzed, based on data provided by the manufacturer. An accumulated degradation of about 27.4% was estimated at the end of 20 years, resulting in a final SOH of 72.6%. These values confirm the need to adopt the EOL criterion as the basis for sizing, allowing the system to maintain reliability and compliance with grid requirements throughout the entire project lifetime. Although this study has focused mainly on the technical aspects, there are significant economic implications. The oversizing of the system leads to considerable additional costs, especially during periods of low renewable production, when the effective utilization of the BESS is reduced. Therefore, it would be pertinent in future work to integrate a detailed cost-benefit analysis, evaluating economic feasibility and possible optimization strategies, such as multiservice operation (energy arbitrage, frequency regulation, and reserve services). In summary, it is concluded that the implementation of a BESS in a photovoltaic power plant is a technically feasible solution, aligned with the needs of the National Electric System, contributing to grid stability and to the maximization of renewable energy utilization. The study also reinforces the importance of proper sizing and long-term planning, ensuring the sustainability and reliability of storage solutions in the context of the energy transition.
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Battery Energy Storage System Photovoltaic Energy End-of-Life Sizing Baterias Medição de fim de vida Energia fotovoltaica
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