Closed-Loop Identification and PID Retuning of Self-Excited Oscillatory Process from Poor PID Controller Tuning

Abstract

We present a model identification method for a self-excited oscillatory process, which uses only the time series data of oscillation and PID parameters. This method is applicable to cases where the self-excited oscillation is caused by unsuitable PID parameters. The models being identified include an integral system and a first-order delay system with dead time. Because system identification experiments are not required, the method can be applied to any historical operation data if the PID parameters are known. Additionally, the PID control parameter design for the integral system proposed in the previous study is extended to a first-order delay system. The new proposed method is applied to a vinyl acetate monomer (VAM) process simulator. Closed-loop identification of nine PID control loops with self-excited oscillations is performed, and the plant operation is stabilized at once without retuning using the obtained PID parameters.