Control of a boiler-turbine unit using MPC-based reference governors

An optimization-based scheme is proposed to improve safety and economical performance of a boiler turbine system controlled by a set of interconnected PI controllers. The scheme, referred to as a reference governor, optimizes the references fed to the PI controllers in such a way that constraint satisfaction is enforced and tracking performance is improved. The proposed solution allows the plant operator to keep the existing PI control architecture and improve its performance by using an additional layer of control. The reference governor is based on optimizing the predicted future evolution of the closed-loop system, which consists of the plant and the inner PI controllers. Disturbance modeling is used to reject influence of the model-plant mismatch and to improve tracking performance. A case study is offered to demonstrate viability of the proposed approach with respect to energy savings and plant safety. (C) 2016 Elsevier Ltd. All rights reserved.