Electrical and thermal integration modeling of a hybrid supply system

Novel telecommunications services must be supported by a widespread infrastructure and technological advances. Radio Base Stations (RBSs) belong to the mobile services infrastructure and, since they are connected to the grid, they represent a relevant source of costs and energy consumption to ICT operators. For this reason, ICT operators are working on internal power production in RBSs, instead of being passive loads to the electrical grid. In the framework of the ONSITE project (financed by FCH JU, Grant No. 325325, www.onsite-project.eu), which deals with a hybrid (fuel cell and batteries) RBS supply system, a modeling activity was carried out to optimize the system operations. The developed algorithms separately implement a SOFC system and a high temperature (SNC) battery for design purpose and collect them in a unique model for devices interaction (i.e. power production, storage, and control). Moreover, a CFD battery model was developed to analyze the heat transfer while the SOFC stack generates excessive heat during operation and outlet hot gases can be effectively used. Since the SNC batteries need heat during charging process (to maintain their operating temperature) and, conversely, the reactions are exothermic in discharge mode, the described approach aims at combining SNC batteries with micro-CHP unit to optimize the energy flows. The implementation required several alternative designs and variant analysis to secure proper operation of battery and power generation unit.