Management and control of energy storage systems for stationary and automotive applications

PORRU, MARIO

2015-04-28

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Abstract

This PhD dissertation has presented a number of scenarios in which Energy Storage Systems (ESSs) can be usefully employed for increasing energy system performances. Particularly, after introducing the State-of-the-Art of ESS technologies (Chapter 1), reference has been made to some stationary and automotive applications. Stationary applications have regarded Renewable Energy Sources (RESs) exploitation issues and EV integration within micro-grids (Chapter 2). It has been shown that ESSs are particularly useful in compensating for RES forecasting errors, whereas they are much less effective as energy buffers. In addition, Vehicle to Grid (V2G) has also been revealed as an alternative and viable solution for increasing RES penetration level and micro-grid autonomy, even in presence of small EV fleets. The promising results obtained in the energy management of power systems by means of the use of V2G and G2V paradigm have suggested the integration of Electric Vehicles (EVs) into the power system. This requires that EV energy storage systems should satisfy both electric propulsion and power system requirements. With this aim, the design and management of a novel Hybrid Energy Storage System (HESS) for EVs has been considered (Chapter 3). Particularly, the proposed configuration allows the reduction of the peak current delivered by EV batteries, thus preserving their rated performances and increasing their lifetime. This goal has been achieved by means of a suitable management of the energy flows provided by the HESS, leading to a good exploitation of the proposed topology. The effectiveness of the proposed solutions has been verified through several extensive simulation studies, which have been carried out in the Matlab environment. In conclusion, it can be stated that all cases have revealed the need of carefully sizing and managing ESSs in order to achieve optimal results. In this context, it is worth noting that the employment of large ESS easily leads to enhanced performances but also to significant increased costs. This drawback cannot be sustained, especially in automotive applications, in which EV competitiveness is strictly related to a decrease of ESS size, weight and costs. On the other hand, small ESSs do not generally guarantee the same performances but they can be quite similar if optimal management and control strategies are employed. These last thus will cover a fundamental role in making ESS more widespread, enabling an optimal trade-off among increased performances, costs, management and control issues.