The PI controller design for a liquid level system using the weighted geometric center method is discussed. Every real-time process have dead time. This dead time leads to the generation of oscillation in the system response. The oscillation generated due to dead time introduces instability in system performance. This paper presents a tuning method based on calculating a geometric center in the stability region for a higher order system. In this, the stability region calculated by plotting (Kp , Ki )-plane based on boundary locus stability technique. Further centre point computed in the stability locus by a geometric center method. This center point will provide Kp , Ki value for tuning the PI controller. The First Order Plus Dead Time (FOPDT) process considered to elaborate the method for computing the tuning parameters. A nonlinear time-delay system and a plant having time-delay response are controlled in simulation. The performance of the newly obtained PI controller based on weighted geometric center method is compared with the existing results to show the usefulness of the control scheme. Moreover, disturbance rejection ability of the newly obtained PI controller based on weighted geometric center method is demonstrated by applying disturbances. In addition, the designed controller implemented using Siemens DCS PCS7 V8.1 platform.
Design of PI controller for Liquid Level System using Siemens Distributed Control System