Dynamic on-line optimization of production processes
First Claim
1. A method for a production process having a number of process sections the method comprising:
- obtaining a dynamic process model having time dependent relations between manipulated variables for said process sections and process output variables from respective process section;
providing external constraints for said production process for a prediction time interval;
measuring a set of process output variables of said production process;
estimating an initial state by using said measured process output variables;
defining an objective function involving predicted controlled process output variables for said prediction time interval and said external constraints;
said predicted controlled process output variables being defined by said dynamic process model based on said initial state;
optimizing said objective function under constraints imposed by said dynamic process model and/or said external constraints, by adapting said manipulated variables, giving input trajectories for said manipulated variables for said prediction time interval; and
operating said production process by setting said manipulated variables according to said input trajectories during a control time interval.
2 Assignments
0 Petitions
Accused Products
Abstract
A process is modeled by a dynamic model, handling time dependent relations between manipulated variables of different process sections (10A–D) and measured process output variables. Suggested input trajectories for manipulated variables for a subsequent time period are obtained by optimizing an objective function over a prediction time period, under constraints imposed by the dynamic process model and/or preferably a production plan for the same period. The objective function comprises relations involving predictions of controlled process output variables as a function of time using the process model, based on the present measurements, preferably by a state estimation procedure. By the use of a prediction horizon, also planned future operational changes can be prepared for, reducing any induced fluctuations. In pulp and paper processes, process output variables associated with chemical additives can be used, adapting the optimization to handle chemical additives aspects.
-
Citations
48 Claims
-
1. A method for a production process having a number of process sections the method comprising:
-
obtaining a dynamic process model having time dependent relations between manipulated variables for said process sections and process output variables from respective process section; providing external constraints for said production process for a prediction time interval; measuring a set of process output variables of said production process; estimating an initial state by using said measured process output variables; defining an objective function involving predicted controlled process output variables for said prediction time interval and said external constraints; said predicted controlled process output variables being defined by said dynamic process model based on said initial state; optimizing said objective function under constraints imposed by said dynamic process model and/or said external constraints, by adapting said manipulated variables, giving input trajectories for said manipulated variables for said prediction time interval; and operating said production process by setting said manipulated variables according to said input trajectories during a control time interval. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 40, 41, 42, 43, 44, 45, 46)
-
-
24. A production process system, comprising:
-
a number of process sections, controllable by manipulated variables; sensors measuring a set of process output variables of said production process; processor means, connected to said sensors; process section control means, setting said manipulated variables, said process section control means being connected to said processor means; said processor means in turn comprising; means for obtaining a dynamic process model having time dependent relations between manipulated variables for said process sections and process output variables from respective process section; means for providing external constraints for a prediction time interval; means for defining an objective function involving predicted controlled process output variables for said prediction time interval and said external constraints; said predicted controlled process output variables being defined by said dynamic process model based on an estimation of an initial state obtained by said measured set of process output variables; means for optimizing said objective function under constraints imposed by said dynamic process model and/or said external constraints by adapting said manipulated variables, giving input trajectories for said manipulated variables for said prediction time interval; whereby said process section control means is arranged for setting said manipulated variables according to said input trajectories during a control time interval.
-
-
25. A system for a production process having a number of process sections, controllable by manipulated variables, comprising:
-
processor means; and process section control means, setting said manipulated variables, said process section control means being connected to said processor means; said processor means in turn comprising; sensor input means for receiving a set of process output variables of said production process; means for obtaining a dynamic process model having time dependent relations between manipulated variables for said process sections and process output variables from respective process section; means for providing external constraints for a prediction time interval; means for defining an objective function involving predicted controlled process output variables for said prediction time interval and said external constraints; said predicted controlled process output variables being defined by said dynamic process model based on an estimation of an initial state obtained by said measured set of process output variables; means for optimizing said objective function under constraints imposed by said dynamic process model and/or said external constraints by adapting said manipulated variables, giving input trajectories for said manipulated variables for said prediction time interval; whereby said process section control means is arranged for setting said manipulated variables according to said input trajectories during a control time interval. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 47, 48)
-
Specification