Multivariable predictive control of a photobioreactor system

This paper describes the implementation and validation of a model predictive controller (MPC) for a photobioreactor system. The microalgae concentration, the solution pH and the illumination index, which is related to the lit PBR volume, are simultaneously controlled at imposed setpoint values by manipulating the dilution rate, the flow of CO 2 supplied to the culture and the incident light. The complex, time consuming nonlinear optimization is replaced by iterative quadratic programming optimizations. With a reduced number of tuning parameters and no demand for dynamics decoupling, the proposed controller improves considerably the speed of the control loop compared to the results available in literature.