Hierarchical Non-linear Control of a Tubular Photobioreactor

This work presents the development of a hierarchical control strategy for microalgal production. The proposed control scheme is composed of two layers. A lower layer focused on pH set-point tracking and where two different control algorithms were evaluated, a PI plus feedforward compensator and a Practical Non-linear Model Predictive Controller. The upper layer is in charge of calculating optimal pH set-points based on economic criteria to maximize profits, computed as the difference between the incomes obtained from the final production sale and the associated production costs (including the environmental impact of the exhausted CO2 losses). Two types of models have been used depending on the requirements of each layer. Simulated results of the proposed hierarchical control architecture are presented.