Title: Wiener model-based CDM-PI controller for pH neutralisation process

Authors: B. Meenakshipriya; S. Manikandan

Addresses: Department of Mechatronics Engineering, Kongu Engineering College, Perundurai-638052, Tamilnadu, India ' Department of Mechatronics Engineering, Bannari Amman Institute of Technology, Sathyamangalam – 638401, Tamilnadu, India

Abstract: This work focuses on the design and implementation of Wiener model-based PI controller for a pH neutralisation system using coefficient diagram method (CDM). The dynamic model of a pH system is developed based on conservation balance principle by considering sodium hydroxide (NaOH, 0.1N) and hydrochloric acid (HCl, 0.1N) as reactants and it is modelled in MATLAB-Simulink platform. The pH system is approximated as first order plus time delay (FOPTD) model using step test method for computing the controller parameters. The curve fitting technique and inverse Lagrangian interpolation method are used to develop the nonlinear static element and inverse nonlinear static element of Wiener model. The performance of Wiener model-based CDM-PI controller (WMCDM-PI) is analysed and compared with conventional Wiener model-based Ziegler-Nichols (ZN) and internal model control (IMC) PI controllers at the critical operating points of pH 6 and 8. The simulation results prove the superiority of WMCDM-PI over conventional controllers.

Keywords: pH neutralisation; Wiener model; coefficient diagram method; CDM-PI; inverse Lagrangian interpolation; curve fitting; dynamic modelling; conservation balance principle; sodium hydroxide; hydrochloric acid; PI control; simulation; controller design.

DOI: 10.1504/IJMIC.2015.071889

International Journal of Modelling, Identification and Control, 2015 Vol.24 No.2, pp.127 - 137

Accepted: 02 Mar 2015
Published online: 22 Sep 2015 *

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