An optimal hierarchical control scheme for smart generation units: an application to combined steam and electricity generation

Optimal management of thermal and energy grids with fluctuating demand and pricesrequires to orchestrate the generation units (GU) among all their operating modes. Ahierarchical approach is proposed to control coupled energy nonlinear systems. Thehigh level hybrid optimization defines the unit commitment, with the optimal transitionstrategy, and best production profiles. The low level dynamic model predictive control(MPC), receiving the set-points from the upper layer, safely governs the systems consid-ering process constraints. To enhance the overall efficiency of the system, a method tooptimal start-up the GU is here presented: a linear parameter varying MPC computesthe optimal trajectory in closed-loop by iteratively linearising the system along the previ-ous optimal solution. The introduction of an intermediate equilibrium state as additionaldecision variable permits the reduction of the optimization horizon,while a terminal costterm steers the system to the target set-point. Simulation results show the effectivenessof the proposed approach.