MIQP-BASED MPC IN THE PRESENCE OF CONTROL VALVE STICTION

Stiction in control valve is the most common and long standing problem in process
industry, resulting in oscillations in process variables which subsequently lower product
quality and productivity. In this paper, we investigate the effect of avoiding the deadband
region of stiction using Mixed-Integer Quadratic Programming (MIQP) based
Model Predictive Controller (MPC). Different scenarios of control valve stiction are
considered. Simulation studies using an industrial case study of fluid catalytic cracking
unit (FCCU) show that, if the dead-band value is known a-priori, the MIQP-based MPC
can effectively improve the closed-loop performance in the presence of stiction through
the reduction of oscillations in the process variables.