A Flexible Economic MPC Approach for Multimode Operation of Industrial Systems

Industrial multimode operation commonly exists in chemical process control systems. The fundamental mechanism is classifying operational modes and identifying the local models w.r.t. typical operating conditions, such that the global dynamic characteristics can be aligned with the switching control strategies for flexible operation demands. This article proposes a novel integrated economic predictive control (EMPC) method, to account for the mutual coupling economic optimization objectives and overlapping feasible regions in mode decision-making and dynamic control. In the proposed EMPC formulation, the prediction and optimization are carried out on all of the switched-admissible modes, which have been predetermined together with the stabilization conditions at the preliminary stage. The switching signal and input sequences are combined-optimized for achieving the best accumulated economic cost defined on the optimal predicted trajectories. The switching feasibility, and local/global stability under specified DT constraints are guaranteed by the stabilization constraints designed in EMPC. Through theoretical analysis and simulation comparisons, the proposed approach is demonstrated to tackle with the infeasible problem that inevitably arises in the classic hierarchical decision-making architectures; moreover, it exhibits better closed-loop accumulated economic cost in the illustrated cases.