Liquid level control system using observer based constrained discrete-time model predictive control

Abstract

The liquid level control system is extensively used in chemical process industries, boiler process, distillation column of oil refineries in petrochemical industries. The liquid level control in the coupled tank system (CTS) is difficult to incorporate owing to its non-linear characteristics. Furthermore, its physical constraints also pose complexity in its control design and implementation. This paper aims to present in a systemic way the application of model predictive control (MPC) strategy for a coupled tank system (CTS). In this paper, a single-input singleoutput (SISO) system configuration has been considered. This system is comprised of an input flow control valve as the main control of the level of liquid in one tank or both the tanks. For this paper a MPC algorithm is formulated which is described below. It focuses on the modeling and design of the liquid level system. The steps involved in the design of the MPC controller are: development of a state space model for the coupled tank system, incorporation of noise and system identification, optimization, design of constrained discrete-time model predictive control (DMPC) controller for the developed system model.