Control relevant modeling and nonlinear state estimation applied to SOFC - GT power systems

In this article, a dynamic, lumped model of a Solide Oxide Fuel Cell (SOFC) is described, as a step towards developing control relevant models for a SOFC combined with a gas turbine (GT) in an autonomous power system. The model is evaluated against a distributed dynamic tubular SOFC model. The simulation results confirm that the simple model is able to capture the important dynamics of the SOFC and hence it is concluded that the simple model can be used for control and operability studies of the hybrid system. Several such lumped models can be aggregated to approximate the distributed nature of important variables of the SOFC. Further, models of all other components of a SOFC-GT based autonomous power system are developed and a control structure for the total system is developed. The controller provides satisfactory performance for load changes at the cost of efficiency.