Lithium-Ion Energy Storage Systems in Smart Grid Applications: Modeling and Analysis

Nowadays, modern smart grids require the implementation of Energy Storage Systems (ESS) in order to optimize the production, the consumption and the distribution of electrical energy. In particular, ESS adds a degree of freedom to the system which allows to cover the mismatch between production and demand while providing other grid support services. Lithium Ion Batteries have proven to be mature to serve in several applications involving different stakeholders. In fact, their characteristics in terms of aging, specific power and response times overcome other energy storage technologies. In the first chapters of the thesis typical energy storage applications as well as lithium ion batteries are clustered and discussed. The aim of the thesis is to develop and to study a model which simulates a Lithium-Ion based storage system operating in some selected applications. The model is built in the MATLAB and Simulink environment and it considers several aspects: electrical connections, thermal behavior, aging prediction, controlling and economic performance. Overall, the whole model is created thanks to a careful bibliographic research, a large amount of experimental data and with several personal contributions which make it accurate and flexible. Great relevance is given to the aging model which is developed starting from experimental results and fatigue algorithms: both calendar and cycle aging are considered. Three relevant energy storage system applications are selected and studied: RES-ESS, energy arbitrage and island grid. In all cases a simulation of one year is performed employing the developed model. The operating conditions of the storage system are checked and analyzed throughout the simulation. Aging is the main index to be evaluated to asses the sustainability of the application. Finally, depending on the specific application, revenue sources are identified and calculated. With current Lithium Ion batteries prices, all applications resulted to be hardly economic sustainable. However, considering the decreasing trend of prices, these applications may be very interesting in the medium term (about a decade) confirming the relevance of the research.