Modeling and experimental validation of Battery Energy Storage Systems

The present dissertation is mainly focused on the most used and promising BESS solutions: which are the lithium batteries. Several experimental tests are reported in order to analyse and model the main behaviours of this BESS typology, from the electrical and the thermal point of view. Simulation models of different kind of lithium cells will be designed and validated through experimental tests performed inside Department of Energy, Systems, Territory and Construction Engineering (DESTEC) battery laboratory. Specifically, the problem of the model parameter identification will be displayed, to correctly predict the main cell response in terms of voltage and temperature, with the improvement of expanding the single cell model to simulate a whole battery pack, composed by several cells connected together. The issues of the State-of-Health will be experienced by an experimental aging campaign, which has reported significant results, clearly showing how the increase in electrical stress may drastically reduce the battery life. As a realistic application of BESS solution, a model of a general hybrid/electric forklift truck is developed in collaboration with the partner company. The vehicle main power flows, in function of realistic working operations, are simulated and experimental validated, in order to estimate the most critical situations the on-board battery can be subjected to. Finally, beyond lithium-based batteries, other BESS categories are here analysed. Firstly, a Redox Flow Battery (RFB) put at disposal in DESTEC battery laboratory is tested to underline its specific performance in terms of overall efficiency when integrated with the grid. Secondly, a high-power Nickel Metal-Hydride cell is studied and compared with a lithium cell, testing them under same high power fast charging and discharging conditions.