Classic PID-based control strategies for raceway photobioreactor biomass concentration and water level

This paper presents the simulation implementation of classical control strategies based on PID controllers for the simultaneous control of water level and biomass concentration in open reactors by manipulating the dilution (inflow) and harvested (outflow) flow rates. The system studied is a TITO (two inputs-two outputs) process with coupling between its variables, and a significant amount of disturbances, such as solar radiation, relative humidity and ambient temperature. The proposed strategies combine Controlled Variable (CV) and Manipulated Variable (MV) switching strategies to follow both setpoints and overcome saturation problems. A simulation of six consecutive days with different external climate conditions was performed. The results show that the proposed schemes can significantly improve the basic PID control performance. The proposed solutions are simple and generic, and behaving properly for both controlled variables. Copyright (c) 2024 The Authors. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/)