Error tolerant MPC versus PI control - a crystallization case study

The present work is focused on a comparative study between the classical PI(D) control and an error tolerant modification of the nonlinear MPC approach implemented to a fed-batch sugar crystallization process. Two scenarios are considered: i) (nominal case) MPC versus PI assuming no disturbances or noise and ii) MPC versus PI with disturbances and noise due to original industrial data implemented in the tests. The results demonstrate that the MPC outperforms the PI control with respect to the final batch performance measures (less energy consumption, improved crystal size parameters and higher productivity). The usual high MPC computational costs are significantly reduced by the proposed error tolerant modification of the optimization procedure.