Design of Decentralised PI Controller Based on Characteristic Ratio Assignment Method for a Waste Water Treatment Plant

Abstract

This work proposes a decentralised PI controller design for a wastewater treatment plant (WWTP) based on the Characteristic Ratio Assignment (CRA) method. To minimise interactions, a decoupler is created, and for every decoupled subsystem, the First Order Plus Dead Time (FOPDT) model is derived. Using the CRA technique, the independent controllers for each lower order FOPDT decoupling subsystem are calculated. This paper presents the design of a decentralized proportional–integral (PI) controller for a wastewater treatment plant (WWTP) and it is found that the controller is designed based on minimizing settling time and to indicate desired robustness using uncertainty. To verify the performance and stability of controllers are presented. Using the intended controllers, WWTP simulations are run in the MATLAB environment to confirm their stability and performance.