Boot camp advanced tools and techniques

EMERSON Process Management Educational Services Copyrighted Material / Duplication ProhibitedAdvanced Tools & Techniques
Advanced Tools & Techniques

Copyrighted Material / Duplication Prohibited
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EMERSON Process Management – Educational Services Advanced Tools & Techniques
Introduction
Over the last 10 years significant improvements made in advanced control
tool capabilities and in user interfaces, improvements that make it easier to
design and commission advanced control solutions.
Also since then, new advanced control applications have been introduced
for batch and continuous processes.
The book Advanced Control Foundation – Tools, Techniques, and
Applications provides a fresh look at some of the latest advanced control
technologies that are available to the process industry. A web site for the
book allows the solutions to the book’s workshops to be viewed using a
web browser.

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Areas to be Addressed
This session will provide an overview of the more common technique that
may be used to improve process operations. Areas that will be addressed
are:
• Evaluating Control System Performance (Demo)
• Tuning - Integrating Process, Units Conversion(Workshop),
• Intelligent PID (demo)
• Adaptive Tuning
• Fuzzy Logic Control
• Property Estimation - Neural Networks(NN) and Other Technique
• Model Predictive Control (MPC) with Optimization
• Integrating Advanced Control Into an Older DCS

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Basis for Presentation
Material that will be presented is
based on Advanced Control
Foundation.
This book was published in Sept
2012 by ISA and addresses the
advanced control products in the
DeltaV control system (or targeted
for a future DeltaV release).
The book may be purchased on-line
through ISA or Amazon.

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Basis for Presentation (Cont)
The solution to workshop included in the book may be viewed using your web
browser- see http://www.advancedcontrolfoundation.com/

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Evaluating Control System
Performance

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Plant Operating performance
The latest UI
technology allows the
plant operator to do
more.
Graphic displays and
historic trends allow
the operator to view
and interact with
discrete and continuous
control
Operator must depend
on the control system to
maintain target
operating condition to
achieve best
performance.

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Issues Confronting The Process Industry
In many cases the staffing at the plant level has been reduced. Plant
support at the corporate level may have been severely downsized or
eliminated.
Process engineers and instrumentation technicians may not have
sufficient training to fully understand control setup and tune PID loops
for best performance.
Resources at the plant level may only be sufficient to address issues
that disrupt production.
The impact of control utilization/performance may not be monitored,
documented and/or effectively communicated to plant management.
This is a global issue – Not specific to the control system
manufacturer, commonly encountered in many major plants located in
the US, Europe, Asia Pacific, Middle East.

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Evaluating Control System Performance (Cont)
A plant equipped with the
latest control systems and
field instrumentation may
still be found to have low
control utilization.
Often the key to getting
control loops back on
automatic is for plant
management to be aware of
the low control utilization
and its impact on product
quality and production rate.

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Performance Monitoring
Measurement status and control mode as defined by IEC61804 are key to
performance monitoring

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Performance Monitoring - Example
DeltaV Insight allows easy navigation of
control hierarchy
Overview display summarizes
performance for System, Area, Units and
Modules
Abnormal Control Conditions indicated
for Problem Loops:
• Control Service Status:
− Incorrect mode
− Limited control output
− Bad/Uncertain input
• Control Performance Status:
− Standard Deviation
− Variability Index
− Oscillation Index
− Tuning Index
• Device and Valve Diagnostics

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Process Area Overview

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Summary View of a Process

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Module View

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Detail View of Block Performance

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Performance Reports - Example
Report generation is an
important feature of
performance monitoring
tools.
Reports can be used to
gain the management
support that is required
to address low control
utilization or to
determine the source of
excessive process
variation that impacts
production or product
quality

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Resolving Problems that Impact Control Utilization

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Resolving Problems that Impact Process Variation

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On-Demand Tuning
Where low control
utilization is due to PID
tuning, then On-demand
tuning may be used to
commission the loop. May
be quickly applies
Captures process dynamics
in the field (controller or
device) to allow better
process identification,
particularly for the fastest
loops.
May be used to tuning PID
for control of self-regulating
and integrating processes

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Advanced Tools – Entech Toolkit
Not normally required.
Some customers (pulp
and paper industry) have
adopted this tool.
May be used by specialist
trained on this tool to
identify and resolve
causes of process
variation and loop
interaction.
Advanced tuning
techniques may be
applied when addressing
complex process
dynamics.

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Tuning - Integrating Process,
Units Conversion

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DeltaV On-Demand Tuning
May be used to tune PID
used for control of a self-
regulating process or an
integrating process.
Especially helpful for
tuning integrating
processes or processes
characterized by slow
dynamics.

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DeltaV On-demand Tuning (Cont)
When the on-demand
tuning application resides
in a DCS workstation,
communications between
the controller and the
workstation can introduce
variable delay and jitter in
the observed process
response.
To allow the process to be
accurately identified, the
on-demand tuning in
DeltaV is distributed
between the workstation
and the controller/ field
device.

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Manually Tuning an Integrating Process
Manual tuning is
complicated by the fact
that it is difficult to
establish process
characterization from
step response because of
changing process
conditions that prevent
establishing a steady
state condition.

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Manually Tuning an Integrating Process

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System Migration - Equivalent DeltaV Tuning
When an older system is
replaced with DeltaV then
if the tuning units of the
older system are different
than those used in deltaV,
then it will necessary to
convert the tuning from the
older system to the
equivalent tuning in
DeltaV.
An Excel spreadsheet has
been created to
automatically do this
conversion from Provox
tuning to equivalent DeltaV
tuning.

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Workshop
1. Open the workspace for the Three Element Level Control application. Change the
setpoint and observe the response using the chart. Adjust the reset tuning to provide a
slower closed loop response. Change the setpoint observe the response using the
chart.
2. Install on your laptop the Excel spreadsheet for conversion of Provox tuning to
equivalent DeltaV Tuning.
3. Enter the following Provox tuning and examine the equivalent DeltaV tuning.
• Loop Tag: FIC110
• Proportional Gain: 0.4
• Reset: 30 repeats/min
• Rate: 0
4. Examine the equations that are used for the units conversion.

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Three Element Level Control

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Intelligent PID

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PIDPlus Feature of DeltaV PID
The PIDPlus feature of the
DeltaV PID (DeltaV v11
and higher) is enabled
through the FRSIPID_OPTS
parameter.
When PIDPlus is enabled
then special behavior is
provided to address:
• Control using Wireless
measurement or sampled
inputs provided by an
anlayzer
• Recovery from process
saturation conditions.

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PIDPlus for Wireless Control
The Challenge – Control Using Wireless
Transmitter power consumption is minimized by reducing the number of times
the measurement value is communicated.
Conventional PID execution synchronizes the measurement value with control
action, by over-sampling the measurement by a factor of 2-10X.
The rule of thumb to minimize control variation is to have feedback control
executed 4X to 10X times faster than the process response time (process time
constant plus process delay).
The conventional PID design (i.e., difference equation and z-transform) assumes
that a new measurement value is available at each execution and that control is
executed on a periodic basis.

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Conventional Approach – Over Sampling of
Measurement
Control Execution
63% of Change
Process Output
Process Input
Deadtime (TD )
O
I
New Measurement Available
Time Constant ( )

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Conventional PID - Impact of Wireless
The underlying assumption in traditional control design is that the PID is
executed on a periodic basis.
When the measurement is not updated on a periodic basis, the calculated reset
action may not be appropriate.
If control action is only executed when a new measurement is communicated,
this could result in a delayed control response to setpoint changes and
feedforward action on measured disturbances.
Conventional PID Design

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*WirelessHART Communication
Window communication is the preferred method of communications for control
applications. A new value will be communicated only if:
• The magnitude of the difference between the new measurement value and the
last communicated measurement value is greater that a specified trigger value
• or if the time since the last communication exceeds a maximum update
period.
Thus, the measurement is communicated only as often as required to allow
control action to correct for unmeasured disturbances or response to setpoint
changes.
For Windowed mode you must specify an update period, a maximum update
period, and a trigger value.
*HART 7 specification that has been adopted as an international standard, IEC
62591Ed. 1.0.

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PID Modification for Wireless Control
To provide the best control for a non-periodic measurement, the PID must be
modified to reflect the reset contribution for the expected process response since
the last measurement update.
Control execution is set faster than measurement update. This permits
immediate action on setpoint change and update in faceplate.

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PIDPlus Using Wireless Transmitter vs. Conventional
PID and Wired Transmitter
Control
Measurement
Control Output
Unmeasured
Disturbance
Setpoint PIDPlus
PIDPlus
PID
PID
Lambda Tuning ʎ = 1.0
Communication Resolution = 1%
Communication Refresh = 10sec

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Control Performance Difference
Communications transmissions are reduced by over 96 % when
window communication is utilized.
The impact of non-periodic measurement updates on control
performance as measured by Integral of Absolute Error (IAE) is
minimized through the PID modifications for wireless
communication.

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PIDPlus - Modified Derivative Action

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PID Performance for Lost Communications
The Conventional PID provides poor dynamic
response when wireless communications are lost.
The PID modified for wireless control provides
improved dynamic response under these conditions

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Wireless Communication Loss – During
Setpoint Change
Communication Loss
PID
PIDPlus
PIDPlus
PID
Control
Measurement
Control Output
Setpoint

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Wireless Communication Loss – During
Process Disturbance
Communication Loss
PIDPlus
Setpoint Control
Measurement
Control Output
PID
PIDPlus
PID

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Installation at Broadley James
Portable Hyclone 100
liter disposable
bioreactor
Rosemount
WirelessHART
gateway and
transmitters for
measurement and
control of pH and
temperature.
Pressure monitored
BioNet is based on
the DeltaV Control
system.

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Broadley James Bioreactor Setup
Bioreactor
VSD
VSD
TC
41-7
AT
41-4s2
AT
41-4s1
AT
41-2
AT
41-1
TT
41-7
AT
41-6
LT
41-14
Glucose
Glutamine
pH
DO
Product
Heater
VSD
VSD
VSD
AC
41-4s1
AC
41-4s2
Media
Glucose
Glutamine
VSD
Inoculums
VSD
Bicarbonate
AY
41-1
AC
41-1
Splitter
AC
41-2
AY
41-2
Splitter
CO2
O2
Air
Level
Drain
0.002 g/L
7.0 pH
2.0 g/L
2.0 g/L
37 oC
MFC
MFC
MFC
AT
41-5x2
Viable
Cells
AT
41-5x1
Dead
Cells
Bioreactor
VSDVSD
VSD
TC
41-7
TC
41-7
AT
41-4s2
AT
41-4s1
AT
41-2
AT
41-1
TT
41-7
AT
41-6
LT
41-14
Glucose
Glutamine
pH
DO
Product
Heater
VSD
VSD
VSD
AC
41-4s1
AC
41-4s1
AC
41-4s2
AC
41-4s2
Media
Glucose
Glutamine
VSD
Inoculums
VSD
Bicarbonate
AY
41-1
AC
41-1
AC
41-1
Splitter
AC
41-2
AC
41-2
AY
41-2
Splitter
CO2
O2
Air
Level
Drain
0.002 g/L
7.0 pH
2.0 g/L
2.0 g/L
37 oC
MFC
MFC
MFC
AT
41-5x2
Viable
Cells
AT
41-5x1
Dead
Cells

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Wireless Temperature Loop Test Results

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Wireless pH Loop Test Results

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Separations Research Program, University of Texas at
Austin
The Separations Research Program
was established at the J.J. Pickle
Research Campus in 1984
This cooperative industry/university
program performs fundamental
research of interest to chemical,
biotechnological, petroleum
refining, gas processing,
pharmaceutical, and food
companies.
CO2 removal from stack gas is a
focus project for which
WirelessHART transmitters were
installed for pressure and steam
flow control

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Steam Flow To Stripper Heater

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Column Pressure Control

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PC215 On-line Column Pressure Control
The same dynamic
control response was
observed for SP
changes
Original plant PID
tuning was used for
both wired and
wireless control
GAIN=2.5
RESET=4
RATE=1
Wired Measurement
Used in Control
Wireless Measurement
Used in Control

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Control Performance – Wired vs Wireless
Comparable control as
measured by IAE was
achieved using
WirelessHART
Measurements and PIDPlus
vs. control with wired
measurements and PID.
The number of measurement
samples with
WirelessHART vs Wired
transmitter was reduced by a
factor of 10X for flow
control and 6X for pressure
control – accounting for
differences in test duration.
Test #1 Test #2

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Recovery From Process Saturation
The recovery of the PID from
process saturation is critical in
many continuous and batch
applications.
By utilizing a variable preload
when the PID output is limited
for an extended period of time
(process saturation), it is
possible to minimize setpoint
overshoot on recovery from
saturation.
PI Control with Variable Pre-load
PI Control

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PIDPlus for Recovery From Process Saturation
The PIDPlus option in DeltaV v11 provides improved the control response for recovery
from process saturation.
• PIDPlus option added in DeltaV v11.3 to improve control response for recovery
from process saturation. Anticipation action can be adjusted using the PID
parameter RECOVERY_FILTR. Value of 1 = No anticipation, Value of 0 = full
anticipation utilized to avoid SP overshoot when recovering from process saturation
• The benefit of enabling the PIDPlus option will be shown using several process
examples. Application of PIDPlus in Surge Control will be examined in detail
based on “typical” centrifugal air compressor used in refining industry.

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PIDPlus – Addressing Process Saturation
A process saturation condition exists when the setpoint of a PID can not be
maintained and the PID output is limited.
Three examples will be used to illustrate process saturation conditions :
• Steam header pressure control
• Boiler outlet steam temperature control.
• Compressor surge Control
When operating conditions change that allow the process to recover from a process
saturation condition, then improved response is provided by enabling the
FRSIPID_OPTS option for PIDPlus. Anticipation action can be adjusted using the
PID parameter RECOVERY_FILTR. Value of 1 = No anticipation, Value of 0 = full
anticipation utilized to avoid SP overshoot when recovering from process saturation

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Example – Steam Temperature Control using
PIDPlus
If steam generation exceeds the
attemperator capacity then the
boiler outlet steam temperature
will exceed the outlet setpoint
with the spray valve fully open.
When boiler firing rate is
reduced, then the spray value
should be cut back as the outlet
temperature drops.
When the FRSIPID_OPTS for
PIDPlus is enabled then the valve
moves before PV reached SP –
providing improved response.
Standard PID DeltaV PIDPlus
SP Overshoot
50% Drop in
steam
generation

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Example - Header Pressure Control
Under normal operating conditions the
pressure reducing valve, PV196,
remains close and the 400# header
pressure is maintained by the steam
turbine extraction.
If the turbine extraction can not meet
400# steam demand or the turbine trips
off-line then the PRV valve must open
to maintain header pressure.
A very small improvement in response
for a 40% drop in turbine extraction is
seen since for this example the PV
normally operates close to SP.
Standard PID DeltaV PIDPlus

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Compressor Surge Control
Single-shaft centrifugal compressors
with horizontally split casings are
commonly used in the process
industry
Are preferred for applications
requiring medium pressures and
large volume e. g. cracked gas,
coker gas, process air or carbon
dioxide.
Electric or steam turbine drive
design.

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Compressor Surge
Surge* is the point at which the
compressor peak head capability and
minimum flow limit are reached. If
the operating point approaches the
surge line, the impeller and diffuser
begin to operate in stall and flow
recirculation occurs.
The flow separation will eventually
cause a decrease in the discharge
pressure and flow from suction to
discharge will resume. This surge
cycle will repeat itself unless control
system brings the compressor out of
the surge cycle.
Any surge event can cause severe
damage to the thrust bearings, seals,
and the impeller.
*GMRC Guideline –Version 4.3 Application Guideline for
Centrifugal Compressor Surge Control Systems

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Control Requirements
The primary objective of a surge control system is to prevent the
occurrence of surge so as to reduce possible damage to the compressor
The three primary operating environments for the surge control system
are:
Start-up Environment - In a typical start-up mode, gas is continually recycled to
bring the compressor online. The recycle valve is fully opened upon start-up. As
the compressor begins to gain speed and flow is increased, the recycle valve is
gradually closed.
Normal Process Control Environment –The surge control system must provide
for smooth operation of the compressor over the entire operating range. The shape
of the surge control line will determine the response characteristics of the surge
control system. Precision in recycle valve position control and minimizing
overshoot are required.
Emergency Shutdown Environment - The surge control system must function
quickly to open the recycle valve fully
We will address the normal process control environment.

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Typical Air Compressor
The surge control system
acts as an integral part of the
compressor station controls.
The recommended margin
allowed between the actual
surge line and the surge
control line is 6-10 percent
of the actual flow surge
limit.
Note: The scaling of the compressor performance curve
has been normalized to protect the real plant data.

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Air Compressor – Normal Operations
The function of the surge
control system is to detect
the approach to surge and
provide more flow to the
compressor through
opening the recycle valve
to avoid surge.
Opening of the vent valve
provides more flow and
reduces compressor head,
to move the compressor
away from its surge point.

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Dynamic Compressor Simulation
A dynamic compressor
simulation that matches typical
BP air compressor data was
developed to support testing of
the compressor controls.
The simulation was tied to the
control strategy used for normal
operation.

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Air Compressor Control – Normal Operations
Parameters were
added to support
testing
• Normal Load
Demand
• Process status
• Motor status
BP Tuning for typical
compressor was
utilized

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Control Response – PIDPlus Disabled
Surge Margin
60% Reduction
in Air Demand
Surge Line
Exceeded

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Control Response – PIDPlus Enabled
Surge Margin
60% Reduction
in Air Demand
Surge Margin
Maintained

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Learning More About PIDPlus
• The module that is used in the Intelliegent PID workshop may be downloaded from the
Advanced Control Foundation web site and imported on any DeltaV system (v11 or higher).
• Allows performance of PIDPlus using wireless measurement to be compared to PID with
wired measurement

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Adaptive Control

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On-demand Tuning (Cont)
When using an on-
demand tuning
application, consider
that the process gain
may change with the
operating conditions.
For robust control,
tuning should be based
on the operating
conditions that provide
maximum process
gain.

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Adaptive Tuning
In some cases, the
tuning established at one
operating point may not
provide the best control
for the full operating
range.
Adaptive tuning allows
the process gain and
dynamics to be
automatically identified
and used in control.

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Adaptive Control - Implementation
To allow the data used in
adaptive control to be
collected without
communication skew or
jitter, adaptive control is
implemented directly in
the DeltaV PID
Enables adaptive control
to be utilized even in
high speed control
applications.

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Adaptive Tuning
Allows tuning the process model
to be automatically established
based on:
• Normal setpoint changes
made by the operator when the
PID is in an automatic
• PID output changes when the
PID is in a manual mode.
Model switching with re-centering
and interpolation may be used for
process model identification.

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Viewing Identified Models

1 - 72
View Adaptive Tuning Solution
Advanced Control Foundation web site
http://www.advancedcontrolfoundation.com/adaptive-tuning-solution.aspx

1 - 73
Fuzzy Logic Control

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Predefined Fuzzy Logic Control Function Block

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Fuzzy Logic Control
For some specific process
applications, fuzzy logic
control enables faster
setpoint recovery with less
overshoot than PID control
for both setpoint and load
changes
Fuzzy logic is best suited
for controlling processes
characterized by large time
constants and little or no
deadtime

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Fuzzy Logic Control Workshop

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Property Estimation

1 - 78
Neural Networks for Property Estimation
When a product quality
measurement is available only
from the lab, it is often possible
to use upstream measurements
to calculate an estimated value.
To address the non-linear
response of product quality
parameters to changes in
process inputs, the estimator
can be based on a neural
network model.

1 - 79
Continuous Digester Example

1 - 80
Batch and Continuous Data Analytics
Through the use of on-line data
analytics, it is possible to
provide:
• Product quality predictions
which allow quality problems
to be identified while there is
time to take corrections
action.
• Detection of abnormal
process operation and/or
equipment problems and
support of root cause analysis
Batch Analytics in DeltaV v12,
Continuous Analytics currently
under development.

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Continuous Example – Static Mixer

1 - 82
Batch Example

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Model Predictive Control

1 - 84
Model Predictive Control(MPC) in DeltaV
Three versions of Model Predictive Control (MPC) are provided in DeltaV.
• DeltaV Predict (DeltaV v7 or later) – Addresses processes as large as 8x8.
Pusher capability is provided to allow process throughput to be maximized by
maintaining the process at its operating constraint. No cost if only one(1)
manipulated parameter. Module runs in Controller or Application station.
• DeltaV PredictPro DeltaV v9 or later) - For larger, more complex process as
large as 40x80 . Linear Program (LP) embedded to support process optimization
based on user defined control objective. Module runs in Controller or Application
station.
• DeltaV PedictPlus (DeltaV v12 or later)– Adds greater capability to address
changing operating constraint and integrating processes. Module runs only in
Application station.

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Replacing PID with MPC
DeltaV Predict may be used
to replace PID when the
process is characterized by
large deadtime, multiple
measured distrubances or
constaints.
• No cost if only one
manipulated parameter.
• Designed to be layered
on top PID in existing
control strategy.
One Measured Disturbance Input
MPC Constraint Control

1 - 86
Simple MPC
MPC has proven advantages
over multi-loop PID control
techniques in a variety of
small applications that are
characterized by:
• Long process delay and
interaction,
• Measured disturbances or
constraints
• Production is limited by
process input(s)
Embedded MPC capability in
the control system.is an
advantage

1 - 87
MPC Integrated with Optimization
For larger, more complex
applications that are used in batch or
continuous processing, the plant
operation objective(s) may be best
met using MPC integrated with
optimization i.e. DeltaV PredictPro.
Such applications are often
characterized by numerous operating
constraints and the need to address
broader operating objectives, such as
maximizing throughput while
minimizing production costs
MEE Process
CTMP Process

1 - 88
CTMP Refiner Process Step Response

1 - 89
Example: Lime Kiln Control – DeltaV Predict
View the following videos showing the DeltaV Predict installation at Canfor Pulp and
Paper. These videos are good examples of the types of videos contained on the DeltaV
web site under Video Central.
http://www.youtube.com/watch?v=IwPFqLgh21M
http://www.youtube.com/watch?v=sNlosWA8crE

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Integrating Advanced
Control Into an Older DCS

1 - 91
Integrating Advanced Control Into a DCS
When advanced control is
embedded in the distributed
control system (DCS), the
plant operator has a single
window interface with
consistent system interaction
and single log-in and span of
control.
If the DCS does not support
advanced control, then the
advanced control
applications must be layered
onto the DCS. Several
approaches may be taken
depending on the DCS
support for layered
applications.

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