Multivariable robust MPC design for neutralisation plant: Experimental analysis

Abstract

The paper provides an extensive experimental analysis of offset-free multivariable robust model predictive control (MPC) of a neutralisation plant. The behaviour of the neutralisation plant was nonlinear and asymmetric. The controlled variable was a pH value of the outlet stream, and the manipulated variables were the inlet volumetric flow rates of the acid and base. The observer was designed to estimate the system states. Operating conditions make the tuning of the robust controller a challenging task. First, the conventional robust MPC was designed. The control setup was tuned and experimentally analysed in various operating conditions. Based on the measured data, the novel approach of the real-time compensation of the asymmetric behavior was investigated. Implementation of the proposed control strategy leads to improved control performance. The real-time compensation of asymmetric behaviour can be considered for the control of other systems with nonlinear behaviour.