User`s guide

Section 1 — An Operator’s Quick Tour of Profit Optimizer Displays
1.2 Control Concepts You Need to Understand
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Honeywell Inc.
1.2 Control Concepts You Need to Understand
Know the Name
to Own the
Concept
The Profit Optimizer displays use control terms that might be new to you. If you
are unfamiliar with these terms and the concepts they represent, how Profit
Optimizer goes about its control tasks might remain unnecessarily obscure to you.
Understanding controller states and statuses, and being familiar with the different
variables and how Profit Optimizer uses them are, for example, of fundamental
importance to anyone using the Profit Optimizer displays.
CVs, MVs, DVs,
BDVs and CCs
and Defined
You need to be aware of five important variables in Profit Optimizer: controlled
variables (CVs), manipulated variables (MVs), and disturbance variables (DVs),
bridge DVs (BDVs) also referred to as bridge outputs and combined constraints
(CCs). Profit Optimizer uses these variables in its prediction and control
calculations. Table 1-1 defines the Profit Optimizer variables.
Table 1-1 How Profit Optimizer Uses CVs, MVs, BDVs and CCs
Variable Description
CV CVs (often called PVs, process variables) are the process conditions to be controlled (the
temperature of an outflow stream can be a CV). To Operators, these are the most
important variables to watch. Setpoints and operating ranges establish the control
objectives for these variables.
Some CVs are continuous inputs to the controller. These values are read and input into
calculations at every controller execution.
Other CVs are periodic inputs to the controller, such as data from analyzers.
MV MVs are the control handles on the process. These are the variables whose conditions
are manipulated (changed) to control the CVs (the gas flow into a furnace can be an MV).
DV DVs are measured disturbances (changes) in the process that influence the CVs but that
are themselves not controllable by Profit Optimizer (the temperature of an inflow stream
can be a DV).
BDV Connects process information between the Profit Controllers. Changes from Profit
Controller’s MVs and DVs that effect CVs in other controllers are transferred through the
BVDs
CC Combined Constraints are steady state variables that are a linear combination fo MVs and
DVs. These variables do not have dynamics and don’t have feedback from the process.
At each execution interval, the controller checks these variables. As their values
change, the controller predicts how the process will change. From these
predictions, the controller calculates suitable control moves (based upon the tuning
and optimization parameters defined for the process).