Non-linear control of a distillation column coupled with MPC and state observer

Abstract

The synthesis of multivariable Globally Linearising Control (GLC) structure coupled with non-linear Reduced-Order Observer (ROO) and external linear controller has been studied for a distillation column. Two different linear controllers, namely Dynamic Matrix Controller (DMC) and conventional Proportional Integral (PI) controller, have been used as external controller within the control structure. The proposed control strategies outperformed a dual-loop PI controller. Simulation results of GLC-DMC combined structure indicated better set point tracking performance under modelling uncertainty than GLC-PI control algorithm. The effects of measurement noise on the controller performance also have been investigated through simulation experiment. A new state reconstruction technique, namely Short-cut Process Model-Based Observer (SPMBO), has been developed. The proposed observation scheme provided superior performance under uncertainty over the ROO within the GLC-DMC and GLC-PI control frameworks.