Identifying the Stabilizing Regions of PI Controller based on Frequency Specifications for a Lab Scale Distillation Column

In this article the authors have made an attempt to design and validate the PI controller based on the frequency based specifications on a lab scale distillation column. In general, the literature reveals the controller design based a specific formula, which leads to a static controller. In lab/Industrial scale most of the processes are dynamic in nature, hence the static controller concepts fail to prove its effectiveness in the presence of dynamic behaviors of the plant. In this article, wide range of stable $\mathrm {K}_{\mathrm {p}}$ and Ki values are plotted with fixed Kd for specific gain and phase margin. The design engineers are permitted to select any $\mathrm {K}_{\mathrm {p}}$ and Ki values based on the closed loop specifications required. The presented algorithm is simulated for the closed loop response of the lab scale binary distillation column model identified by Vinaya and Arasu [6], [7], [8]. The closed loop simulation with 30% uncertainty in all process parameters are also analyzed presented in this article. The Performance measure calculations for servo and regulatory responses are also reported. The experimental validation of the given control algorithm on a lab scale pilot plant distillation column is also found satisfactory to prove the control algorithm effectiveness.