Mathematical modeling and dynamic behavior of a Lithium-Ion battery system for microgrid application

This paper deals with the analysis and simulation of a stationary battery system for microgrid application, where the system structure including battery cells, inverters, filters, transformers, control system and a simplified grid model is described and modeled mathematically. For the simulation of the whole system the software PSCADTM is used. In the first part several equivalent circuit models for Lithium-Ion cells will be compared in order to model the dynamic behavior of the battery system. Particularly the evaluation of the effect of the model's complexity on the dynamics of the entire system will be investigated. In the second part, the dependency of state of charge (SOC), temperature and aging effects of the Lithium-Ion cells on electrical system quantities will be shown. It is also investigated the fact that a high frequency battery model has to be taken into account to describe the cells' dynamics if an inverter with Pulse Width Modulation is used.