Handling disturbances with a zone tracking-oriented stabilizing MPC: enlargement of the domain of attraction

Daniel D. Santana; Márcio A. F. Martins

doi:10.20906/sbai.v1i1.2598

Daniel D. Santana Departamento de Engenharia Química, Escola Politécnica, Universidade Federal da Bahia, Salvador, BA
Márcio A. F. Martins Departamento de Engenharia Química, Escola Politécnica, Universidade Federal da Bahia, Salvador, BA

DOI: https://doi.org/10.20906/sbai.v1i1.2598

Keywords: zone control, enlarged domain of attraction, terminal ingredients, RTO and MPC integration

Abstract

This work focuses on the hierarchical control structure composed of model predictive control (MPC) and real-time optimization (RTO) layers. Here, a zone tracking-oriented infinite horizon MPC strategy with optimizing targets defined by RTO is proposed. This strategy must comply with eventual unreachable targets and unmeasured disturbances. Consequently, its domain of attraction must be enlarged, in order to circumvent infeasibility conditions. This is achieved by imposing terminal equality constraints solely on non-stable states, artificial equilibrium points and softening the bound-type constraints on states with suitable slack variables. Finally, a case study based on an unstable reactor is used to demonstrate the properties of the proposed strategy and the role of the terminal ingredients in the domain of attraction.