Constrained GA Based Online PI Controller Parameter Tuning for Stabilization of Water Level in Spherical Tank System S.P.Selvaraj

Abstract — Level Control of spherical tank is one of the requirements in industries, where the storage of large volumes of highly pressurized liquids takes place. The level control in spherical tank is cumbersome due to variation of cross sectional area with respect to its height. In the proposed work, PI controller is used to control the level of spherical tank. Initially, the Ziegler Nicholas step response method is used to geta first order plus dead time mathematical model and single set of PI parameter.Multiple models or multiple sets of PI controller parameters are also obtained at different operating points using Z-N and online CGA based tuning methods. By conducting experimental study, the servo and regulatory responses of the spherical tank process are obtained with the controller parameters obtained through various tuning methods.The online CGA based tuning method produce better output response with minimum Integral Square Error (ISE) and Integral Absolute Error (IAE) in real-time, with respect to set point and load changes