Model-based development of control strategies for domestic fuel cell cogeneration plants

This paper describes the development of control strategies for domestic fuel cell cogeneration plants, using the simulation environment ColSim [COLSIM-1]. The investigated facility is illustrated, including a fuel cell system fueled with natural gas and a stratified storage with an internal gas burner. The components of this facility are modeled in the used simulation environment ColSim as "plug-flow-types" [COLSIM-02]. Demonstrative of this, the object of a polymer electrolyte fuel cell stack is described. The model of the entire system is shown with the used vector graphic tool [XFIG]. Two criteria are defined optimizing the running costs or the primary energy balance. Based on these definitions control strategies are shown, including the use of a slider for variation. The efficiencies of the system are taken into account in several operating points. In addition the user behavior (electric and thermal energy demands) are considered and acknowledged by the control algorithm. Measured data of a "low energy consumption house", monitored by the German utility EnBW [EnBW-1], are used. In these investigations the user of the facility is premised as the owner. Dynamic tariff structures for natural gas and electricity offer the possibility to influence the operational point of the fuel cell system by the energy supply company. Finally simulation results for the period of one year are illustrated for the defined criteria "ecologic optimized" and "economic optimized". The differences are quantified with the present values of efficiencies for domestic fuel cell power stations and for the electric grid.