Economic optimization of chemical processes based on zone predictive control with redundancy variables

Zone control is to extend the control target from a point to a convex set. Additional degree of freedom can improve the control performance and optimize the economic performance.This additional degree of freedom has been proven to be expressed specifically by redundant control variables.This paper proposes an optimization control strategy based on redundant control variables to improve the economic benefits of zone control. When the system is outside the zone control target, the zone predictive control algorithm is used to preferentially drive the state to the interior of the zone control target. When the system enters the zone control target, it can be directly optimized by using redundant control variables to achieve greater economic benefits. During system operation, each variable is evaluated by the steady-state mapping model, and variables that meet certain conditions are marked as redundant variables. The controller and optimizer are coordinated based on this label for system control and economic performance. Finally, the effectiveness and feasibility of this strategy are verified by numerical simulation. The results show that this strategy can reduce the economic loss of the system. •A multi-stage control strategy for zone control target based on model predictive control was proposed.•A coordination strategy balanced optimization and control was built that is based on redundant input channels.•A search algorithm for redundant input channels and an analysis method for redundant intervals were proposed.