Identifying the stabilising regions of PI controller based on frequency specifications for a lab scale distillation column
by R. Janani; Vinayambika S. Bhat; Indiran Thirunavukkarasu; V.I. George
International Journal of Digital Signals and Smart Systems (IJDSSS), Vol. 4, No. 1/2/3, 2020

Abstract: The aim of the study is to design and implement decentralised PI controller for a lab scale distillation column based on the frequency specifications. Designing an effective PI controller for an MIMO process is a challenging task because of the loop interaction and system with dead time. In order to eliminate these interactions between the control loops, an ideal decoupling technique is implemented and first order plus dead time model is obtained for each decoupled subsystems. By plotting the boundary locus for each subsystems based on the desired gain and phase margin in (k_p, k_i) plane a wide range of PI values are obtained. Also, the performance measurement calculations were compared and tabulated for various values of k_p and k_i with the boundary locus. In this present research the pressure and temperature near the bottom of the column is considered. It is also shown that the system become unstable when the value of PI controller is selected outside the boundary locus.

Online publication date: Fri, 27-Mar-2020

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