Closed-loop identification, diagnosis and retuning of oscillatory PID control loops in chemical processes

The integrated procedure for closed-loop identification and retuning of poorly tuned oscillatory PID control loops is introduced. A process model is identified by comparing time series data of the closed-loops for two different parameter settings, without giving any external perturbation to the operating process. Control parameter calculation is done based on the classical loop-shaping approach. Two case studies are performed on a simulated large scale chemical plant to discuss applicability of the proposed procedure.