Abstract: Model predictive control is used to obtain the best performance value for an objective in a dynamic environment. One or more best performance values for a model predictive application are obtained by utilizing asymmetric dynamic behavior that pushes the process to the edges of the operative window. When a setpoint becomes infeasible, a controller slows down when moving away from a specified setpoint. When the infeasibility clears and the controller starts moving back towards the setpoint, the controller follows a tuned speed. When the controller moves in a direction against economic profit, the controller slows down and when moving in the direction of economic profit, the controller follows the tuned dynamic speed. The controller computes the best performance value for each controlled variable and is equal to the setpoint for the controlled variables with a setpoint or the highest profit value between limits for controlled values affected by economic functions.

Abstract: It is advantageous to switch an active element with a background element. By using a switching mechanism, a background element can be made active while the application remains active. That is, the application does not need to be taken offline to switch the active element with a previously loaded background element. Single input/single output (SISO) relationships are defined for background elements and an active element which provides one or many functions and an active element which provides one or many functions between one input variable and one output variable. The switching mechanism acts on a given SISO relationship to determine the background element to use to replace the active element.

Abstract: The temporary relaxation of constraints permits the efficient and cost-effective operation of certain process models. Ramp imbalances are controlled using soft-landing constraints. Such soft-landing constraints permit a smooth return to a ramp limit which permits continued operation of a system, such as a petrochemical system that includes several inflows and outflows, as opposed to a forced shut-down of the system. A ramp imbalance may be controlled by determining imbalance ramp rates and imbalance set-point ramp rates and using those constraints to resolve the dynamic control problem of a process model.

Abstract: The temporary relaxation of constraints permits the efficient and cost-effective operation of certain process models. Ramp imbalances are controlled using soft-landing constraints. Such soft-landing constraints permit a smooth return to a ramp limit which permits continued operation of a system, such as a petrochemical system that includes several inflows and outflows, as opposed to a forced shut-down of the system. A ramp imbalance may be controlled by determining imbalance ramp rates and imbalance set-point ramp rates and using those constraints to resolve the dynamic control problem of a process model.

Abstract: Model predictive control is used to obtain the best performance value for an objective in a dynamic environment. One or more best performance values for a model predictive application are obtained by utilizing asymmetric dynamic behavior that pushes the process to the edges of the operative window. When a setpoint becomes infeasible, a controller slows down when moving away from a specified setpoint. When the infeasibility clears and the controller starts moving back towards the setpoint, the controller follows a tuned speed. When the controller moves in a direction against economic profit, the controller slows down and when moving in the direction of economic profit, the controller follows the tuned dynamic speed. The controller computes the best performance value for each controlled variable and is equal to the setpoint for the controlled variables with a setpoint or the highest profit value between limits for controlled values affected by economic functions.

Abstract: It is advantageous to switch an active element with a background element. By using a switching mechanism, a background element can be made active while the application remains active. That is, the application does not need to be taken offline to switch the active element with a previously loaded background element. Single input/single output (SISO) relationships are defined for background elements and an active element which provides one or many functions and an active element which provides one or many functions between one input variable and one output variable. The switching mechanism acts on a given SISO relationship to determine the background element to use to replace the active element.