A Multirate Hierarchical MPC Scheme for Ensemble Systems

Multi-rate hierarchical control approaches have gained increased attention in the optimal control of large scale systems due to their usually superior short- and long-term performance compared to distributed approaches and computational advantages compared to centralized controllers.This paper presents a multi-rate hierarchical control scheme for the constrained control of an ensemble system, i.e. a group of individual (similar but heterogeneous) systems that follow a common goal. The approach is based on the definition of a small-scale reference system, which is common for all the subsystems. It allows to define a small-scale ensemble model, to be controlled in a scalable way by the centralized high level of the hierarchy. At the low level, a local shrinking horizon MPC controller is used for each subsystem. Feasibility results are provided and convergence properties are discussed. Finally, the properties of the present approach are illustrated in a case study.