Control Functions - Honeywell Experion PKS Specifications And Technical Data

EP03-300-200
Release 200

Control Functions

Control functions currently supported in the Experion PKS Control Builder libraries are listed in the
Specifications section. Standard available function blocks include Process Variable, Regulatory
Control, Fieldbus (Device and Control blocks), Motor Control, Discrete Logic and Sequential Control,
as well as general-purpose blocks like Flags, Numerics, Timers and Arrays.
Regulatory Control
The regulatory control library includes many standard function blocks, such as PID, PID Feed Forward,
Ratio/Bias, etc. Experion PKS R200 introduces the Profit Loop PKS™ block (PID-PL). Profit Loop
PKS utilizes a Honeywell patented algorithm that represents a single input/single output (SISO) model
predictive controller specifically designed with the operating simplicity and computational efficiency of a
standard PID controller. This allows it to be executed in either the C200 controller or ACE node. Profit
Loop PKS also provides an integrated set of tools (Profit Loop Assistant and Control Builder
Enhancements) that allow easy configuration and model identification.
The Profit Loop function block (PID-PL) is a hybrid of a PID and model based controller; it contains
both PID and Profit Loop capabilities to enable the easy replacement and on-line conversion from an
existing PID to a PID-PL block. Users can take a well-tuned PID controller and directly translate it into
a Profit Loop controller and immediately benefit from improved control delivered by Profit Loop
technology. The PID-PL function block uses a simple process model to predict the effect of past,
present, and future control moves on the process variable. It can be used in place of PID, Smith
Predictors, gap controllers, and optimizers since Profit Loop can anticipate future process behavior.
This allows the controller to know exactly how much to move the process to meet the desired control
objectives. The Profit Loop solution can be used to control temperatures, pressures, flows, discrete
analyzers, tank levels, and it is ideal for control processes with process delay, inverse response, non-
linear effects, and noisy process signals.
The level of effort to configure a PID-PL block is similar to that of the PID, but due to its model-based
formulation, this algorithm outperforms PID while being easier to tune and maintain than conventional
controllers. After its initial model is implemented, Profit Loop controllers are easily adjusted using a
single tuning parameter to obtain the desired control performance. The Profit Loop Assistant and
Control Builder enhancements deliver a variety of tools that greatly simplify the initial determination of
the process model and assist in diagnosing control loop problems:
•
Direct conversion of existing PID tuning to a Profit Loop model
•
Profit Stepper - an automated on-line identification tool that steps the process and calculates
the process model for the user.
•
Basic Model creation based on Loop Type
•
Valve Doctor - diagnoses valve hardware problems prior to controller implementation.
In addition to standard control features, Profit Loop also offers a wide range of expanded capabilities
that extend beyond existing regulatory control algorithms:
•
Anti-windup handling (including handling windup on secondary loops)
•
Range control
•
Target optimization
•
Predictive alarming on controller predictions
•
Asynchronous inputs for direct analyzer control
Profit Loop model implementation results in significantly reduced valve travel that directly translates
into decreased valve maintenance and extended valve life.
Experion PKS CEE-based Controller Specifications and Models
9
December, 2003
Version 1.0