A hierarchical optimization-based scheme for combined Fire-tube Boiler/CHP generation units

In this paper we propose a hierarchical control structure to optimize the behaviour of a generation unit composed of a fire tube boiler, that supplies steam, and a combined heat and power internal combustion engine, which produces the electrical power. Specifically, the higher level addresses the operational optimization and the unit commitment problem of the co-generation in a scenario with price fluctuations and varying demands by solving an hybrid optimization problem; on the other hand, the lower level Model Predictive Controller (MPC), which receives the operation point from the higher level, guarantees that the process constraints of the individual systems are fulfilled. Simulation results are finally presented to show the effectiveness of the proposed scheme.