Hybrid Energy Storage Systems for Smart Grids and Electric Propulsion Systems

Hybrid Energy Storage Systems (HESSs) represent a very promising and viable solution for the widespread diffusion of both Smart Grids (SGs) and Electric Propulsion Systems (EPSs). This is because an HESS benefits from two or more energy storage technologies that are characterized by complementary features, namely high energy and high power densities. Consequently, a number of energy and power services can be provided successfully, which are hardly deliverable by a single energy storage technology unless oversizing is concerned. Therefore, HESSs installed in SGs can provide multiple grid services, ranging from peak shaving to power quality, thus achieving an economic viability. While the employment of an HESS for supplying EPSs enables improved dynamic performances and energy efficiency during both acceleration and regenerative braking, thus extending the vehicle driving range. In this context, an HESS made up of batteries and supercapacitors is the most popular combination, it being suitable for both small-scale and large-scale applications due to its inherent modularity. However, HESS technical and economic viability strictly relies on management and control, which should enable the exploitation of the HESS inherent features to the maximum extent in accordance with the application requirements. In this regard, the presentation will focus on most recent advancements in management and control of HESS for both SG and EPS. Particularly, the most popular HESS configurations, management and control approaches will be introduced at first, highlighting their most important advantages and drawbacks. Subsequently, a highly-integrated HESS configuration will be presented, which is well suited for SGs, but especially for EPSs. This is because it benefits from the advantages of both passive and active HESS configurations due to its inherent flexibility. An Optimal HESS Power and Energy Management (OPEM) for SGs will be presented as well; this has been developed analytically in order to achieve an optimal trade-off between peak shaving and reduced grid energy buffering, providing power quality and preventing an excessive battery cycling at the same time. Preliminary and advanced results will be presented and discussed extensively, which highlight the effectiveness of the proposed solutions in terms of HESS configuration, management and control