Stability and weighted sensitivity analysis of robust controller for heat exchanger

This study presents a parametric system identification approach to estimate the dynamics of a chemical plant from experimental data and develops a robust PID controller for the plant. Parametric system identification of the heat exchanger system has been carried out using experimental data and prediction error method. The estimated model of the heat exchanger system is a time-delay model and a robust PID controller for the time-delayed model has been designed considering weighted sensitivity criteria. The mathematical background of parametric system identification, stability analysis, and H-infinity weighted sensitivity analysis have been provided in this paper. A graphical plot has been provided to determine the stability region in the (K-p,K-i), (K-p,K-d) and (K-i,K-d) plane. The stability region is a locus dependent on parameters of the controller and frequency, in the parameter plane.