Solution of Integrated Process and Control Design Problems with Em - bedded MPC

The potentially significant impact that the design of a process plant can have on its ability to be satisfactorily controlled has led to the development of integrated formulations in which dynamic performance requirements are included as constraints within an optimal design framework. Failure to account for the dynamic operation of a process could lead to reduced profits or even safety and environmental constraint violations. This motivates the need to design the process and its associated control system in an integrated manner. Prior work in simultaneous process and control system design has focused primarily on the use of linear controllers such as proportional-integral control (Mohideen et al., 1996; Bahri et al., 1997; Schweiger and Floudas, 1998; Kookos and Perkins, 2001; Pistikopoulos and Sakizlis, 2002). Baker and Swartz (2004a) considered actuator saturation effects in integrated design and control. This results in model discontinuities, and to avoid potential difficulties with a sequential solution approach in which the integration of the model differential-algebraic equation system is separated from the optimization, they follow a simultaneous solution approach in which the actuator saturation is handled through mixed-integer constraints. They demonstrated that failure to account for actuator saturation could lead to suboptimal designs. The growth in solution time with problem size led to the development of an alternative approach in which saturation was modeled using complementarity constraints, and the resulting problem solved using an interior-point approach (Baker and Swartz, 2004b).