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Control Systems
Useful links from ICEweb sponsors
Terminology
and Symbols in Control Engineering - from our sponsor Samson
Controls
Controllers
and Controlled Systems- A fantastic 60 page document from our sponsor
Samson
Controls
Improving Refinery Performance:Process and Control Information from Step Testing
-Thanks to Tim Olsen, Jim Dunbar and our sponsor Emerson
Process Management- Step testing is typically only used during advanced
control implementation to understand the effects of one
process variable on other process variables. This paper demonstrates how step
testing helped improve process control and process performance around a crude
desalter, hydrocracker hydrogen quench, and gasoline blender.
Other
Links
Glossary
of Process Control Terms - Looking for a Control
Term? You are likely to find it here - John Gerry, P.E., ExperTune Inc.
Basics
and Fundamentals related to Process Automation and Control
Process Instrumentation - Control Systems -
Fieldbus - Advanced Control - and more topics-Thanks to PAControl.com
Dynamic
System Modeling and Control- This exceptional 998 page
resource book is just full of technical information from Hugh Jack and Grand
Valley State University. It is a large download at 5.5Mb but worth the wait!
10.09
The
7 Habits of Highly Successful Controls Engineers - George
Buckbee - Highly successful control engineers didn’t become that way by
accident. The most successful engineers develop habits that improve results and
recognition of those results. This paper addresses specific habits that you can
develop or enhance to be more successful. From ExperTune, Inc.
10.09
Expertune has a fantastic Library of Articles and White papers
covering:
A huge range of control related articles
can be found at Modelling and Control under the headings of;
Basic
Control Theory - Control theory is discussed from
fundamental proportional action to PID control. The dynamic of the simple
control loop is discussed, alongside practical issues of choosing the best
system for the application, and installation and commissioning issues. From
spiraxsarco
Control
Applications - A brief summary of, and advice
on, temperature, pressure, flow and level control methods to suit various
types of steam applications, with consideration to surplussing control,
differential pressure control, and cascade control and installation thereof.
From spiraxsarco
ExperTune
Library - The ExperTune library contains articles,
papers, and video presentations to help you improve your plant's performance.
Loads of control related articles here
Hybrid
control identity crisis - What is in a name? - Differences
between the PLC and DCS architectures, functions, and environments have
diminished during the last decade and a half and only recently are PCs meeting
the need for rugged specifications and high-level support.Hybrid control
provides multi-domain functionality—logic, motion, drives and process -
Samuel Herb and ISA InTech
What
cost migration? - Here is an easy return-on-investment
tool for evaluating the price to upgrade a control system - Knowing when
to wait is just as important as knowing when to upgrade. One needs to clearly
define the costs, risks, and benefits you can expect during the migration
process. This graphical method makes the comparison of migration solutions
clear. From Christopher A. DaCosta / Ken Keiser and ISA InTech
Control
Engineering Virtual Library - This comprehensive
resource from the University of Cambridge gives links to Control Groups Around
the World, Professional Societies, Control Related Journals, Control
Information and other Miscellaneous information.
Fieldbus
- A link to ICEweb's comprehensive Fieldbus page
Advanced Process Control and Optimisation
11.09
The following papers are available thanks to Apex Optimisation.
Experience
with “Grey Box” Modelling and Optimisation of Refinery Processes -
An Rigden, Henrik Terndrup and Marco Smaling. This paper discusses experience
with an alternative approach to process modelling and realtime optimisation at
the Chevron refinery at Pembroke, UK and focuses primarily on the optimisation
of the Heat Exchange Network of the crude unit as an example of the modelling
and real time optimisation of non-linear systems using a “grey box”
modelling approach. Thanks to Apex Optimisation.
Timely
Advanced Control Upgrades: Recapture and Multiply Benefits
- Andrew Taylor - This
paper discusses the establishment of Advanced Process Control (APC) in
refining, petrochemical and oil &
gas production facilities and the various mechanisms which dictate the
lifecycle of an APC application. The
benefits of appropriate APC upgrades are examined with the key elements of a variety of case studies highlighted. The case
studies cited include an APC technology upgrade and various
APC revamps following process context changes (e.g. clean fuels refinery
upgrades). The key elements in an APC
lifecycle management program are proposed. from ProSys Engineering.
Modern
Advanced Control Pays Back Rapidly - From Hydrocarbon
Processing
Optimize
Surge Vessel Control - From Hydrocarbon Processing
Refinery
Fuel System Control and Optimisation - Pavlos
Ioakimidis, Henrik Terndrup, Andrew Trenchard - This paper discusses an
application of Honeywell’s Robust Multivariable Predictive Control Technology
(RMPCT) to the control and optimisation of a refinery fuel system. A plant-wide
fuel system application was commissioned in August 2003 and has delivered
significant financial and operational benefits.
LPG
Fractionation Unit Advanced Control Revamp - Woodside Energy
Ltd and ProSys Engineering Pty Ltd - WEL are mature users of advanced process
control technology with a decade of experience in use of Multivariable
Predictive Control (MPC) technology. This technology uses a dynamic process
model coupled with an embedded optimiser to control multiple input – multiple
output systems. Use of MPC has delivered substantial economic benefits to WEL’s
bottom line and set the company apart from most of their Oil & Gas peers.
Seven MPC applications were commissioned on the Fractionation Unit in early 1997
with an immediate improvement in process stability and profitability. With
gradual change in the process conditions due to throughput increases, the
performance of the MPC had deteriorated. In addition, with the prospect of LPG
production losses being suffered due to Fractionation Unit capacity constraints,
a review of the MPC design with a capacity maximisation focus in mind was
appropriate.
Real
Time Optimisation of Ultra Low Sulphur Diesel Production -Francisco
Arista, Andres Porcel, Pedro Villar, Henrik Terndrup,Marco Smaling - This paper
discusses the experience with real time optimisation of the production of Ultra
Low Sulphur Diesel at CEPSA’s Huelva La Rabida refinery and describes how
these functionalities are integrated as well as some novel techniques used for
the modelling and optimisation of this relatively complex system.
Condensate
Stabiliser MPC Revamp - Most MPC technologies use dynamic
process models coupled with embedded optimisers to control multiple input –
multiple output systems. Dynamic process model accuracy is the proverbial
Achilles’ heel of any MPC application, as model mismatch is the main cause for
MPC application performance degradation. The challenge, however, is often to
determine the causes of the model mismatch. The Stabiliser MPC applications at
the Karratha Gas Plant suffered similar performance degradation problems and the
performance of the applications has gradually degraded over the last few years
to the point where the service factor of the applications had dropped
significantly. This was particularly evident during the summer months when the
applications were not maximising feed rates. ProSys Engineering Pty Ltd now Apex
Optimisation assisted with review and revamp the MPC applications on the
Stabiliser trains, this paper discusses this.
Moomba
Gas Plant Throughput Maximisation - This paper discusses
process control improvement at the Santos Moomba site. One of the initial
objectives was to maximise plant throughput capacity and this was pursued via
three primary mechanisms:
(1) Minimising DP across the CO2 removal trains;
(2) Minimising the LRP inlet pressure in order to facilitate a plant inlet
pressure reduction. This provides immediate production improvement from all
field compressors and provides an improved basis for reconfiguration of the
reciprocating compressors to deliver more flow at constant power (and reduced
field to plant inlet DP).
(3) Using the SWQ pipeline surge capacity to dynamically reduce feed gas supply
to Moomba without reducing the production rate at Ballera. This helps eliminate
spikes of high Moomba inlet pressure which would otherwise result in field
compressor high discharge pressure trips.
Advanced
Process Control Boosts Plant Performance - Andrew Taylor,
Daniel Duff y and Randall Yeates - This article describes an initiative
undertaken by Santos and Apex Optimisation to improve the profitability and
operability of the Port Bonython liquid hydrocarbons processing plant in South
Australia through multivariable predictive control (MPC).
Precipitation
Tanks – Multivariable Predictive Control Magic - This paper
discusses a project to minimise the potential for overflow incidents at an
Aluminium refinery.
Advanced
Process Control - lots of papers thanks to
ControlGlobal.com ( www.controlglobal.com
)
Advanced
Process Control Solutions- Thanks to ControlGlobal.com ( www.controlglobal.com
) and Yokogawa.
Alarm Management
Emerson
Strategies for Abnormal Situation Avoidance & Alarm Management -
This ARC whitepaper highlights that The state of alarm management schemes in
today’s process plants is in crisis. Proliferation of alarms is out of
control, making it almost impossible for end users and operators to
distinguish between critical impending abnormal events and nuisance alarms.
Emerson realises the issues that users are facing regarding alarms and
abnormal situations and has recently unveiled a multi-tiered strategy to
address the issue.-Thanks to our sponsor Emerson
Process Management
Alarms
and Trips: The Ups and Downs - While limit alarm
trips are best known as a sure way to activate a warning light, siren or bell
when a process problem occurs, they are also called upon to do much more. In
fact, today’s highly flexible and versatile alarm trips can be found working
in a wide range of applications, under an impressive list of pseudonyms. From
our valued sponsor Moore
Industries-Pacific, Inc.
12.09
Operators
on alert - Operator response, alarm standards, protection layers keys to safe
plants - David Hatch and Todd Stauffer
- As plants run closer to their performance limits with fewer operators and
support staff, alarm management is becoming paramount to maintaining plant
safety. The key to maximizing the safety protection the operator provides is
creating an environment where they are able to detect, diagnose, and respond to
alarms properly and on time. One way to do this is adopt the requirements and
recommendations of the standard on alarm management (ANSI\ISA-18.2 standard,
Management of Alarm Systems for the Process Industries) and take a coordinated
approach to alarm management and safety instrumented system (SIS) design. The
ANSI\ISA-18.2 standard offers guidance on how alarm management can help a plant
operate more safely. The standard can also bring together the disciplines of
alarm management and safety-system design, which must work more closely to
prevent future accidents. Thanks to InTech and ISA.
Don't
be Alarmed - Avoid unplanned downtime from alarm overload, use top techniques to
improve alarm management - Gary Goble and Todd Stauffer -
Alarm management is one of the most undervalued and underused assets of process
automation. With process automation systems losing $20 billion to unplanned
downtime, and with 40% of it attributed to preventable human error, alarm
management has never been more important. An important factor lending itself to
human errors is the cacophony of alarms, which preclude the operator's ability
to respond quickly and correctly. Thanks to InTech and ISA.
The
Real Cause of Alarm Problems -Chris Wilson: Marketing
Manager, TiPS, Incorporated
Institutionalizing
Alarm Management Part 1 - Covers Alarm
Management history and introduction, Impact
on business, operations, health and safety, Prelude
to the alarm management lifecycle, Publications
& references.
AlarmManagement.com
- A community of people interested in process alarm management.
Share your thoughts and opinions, seek advice, read others' experiences. The
more you know and share, the better industry will be able to manage and
optimize alarms.
The following really good papers by Ian Nimmo are available
from mycontrolroom.com
- Alarm Overload -Ian Nimmo, discusses why most
Distributed Control Systems (DCS) have more standing alarms than necessary, and
how to resolve this problem. Find out how to rescue your plant from alarm
overload utilizing guidelines on personnel responsibility and benchmarking
system performance.
- Alarm Management & Graphics Projects is longer
and more detailed version the Alarm Overload paper - Ian Nimmo -
discusses the benefits of Alarm Management and Graphics Projects i.e., focusing
on life-cycle characteristics and transitioning to maintaining good alarm
management practices, and best practices design methodology on how to approach
graphics development.
- It’s time to consider Human Factors in Alarm
Management - Ian Nimmo discusses implementing procedures to consider human
factors, not simply human error, in control room architecture and reducing the
chance of incidents in plants.
- Abnormal Situational Awareness, the need for
good Situation Awareness- Ian Nimmo -The paper discusses strategies to help
operators maintain a high level of situational awareness i.e., an accurate
perception of the current condition of the process and equipment, and accurate
understanding of the meaning of key performance indicators
Batch Control
The
Safety Issues of Batch (and other) Controls
- Ian Nimmo and
mycontrolroom.com- This paper discusses a new approach to safety, breaking the
traditional barriers of people, organizations and culture and puts the control
engineer back in the driving seat for determining performance improvements,
optimizing control algorithms, people, and the way they interface with
technology.
The Following links come
from the WBF|
White
Paper for Beginners - Three pages that provide basics
of batch control and ISA S88. Charlotta Johnsson, Lund University, Sweden.
White
Paper for Engineers - Discusses briefly the aspects of
S88 of interest to engineers: the physical model, procedural model, equipment
logic and master recipe. Describes practical use of the standard. Bianca
Scholten, TWP Training, The Netherlands.
White
Paper for End Users - The standard defines three
things of importance to end users: a structure that can be applied to almost
any process; terminology to use to describe the process so that others can
understand what you want; and the general function of each of the modules that
make up the structure - Lynn Craig
The
Following excellent links are from ISA
and InTech.
Lather
up with Batch - Matthew Leys and Sean Cahill - Unilever
knew the success of its personal care consumer goods brands rested on the
quality performance of its health and beauty mixing plant and aerosols plant.
Economic growth paired with sound environmental management were just part of
the strategy. Yet a total process control system update would help guide them
to down the road to success. Also included in this article is a second article
- Return to flexible batch automation - The ISA88 standard is easy to
comprehend, but gaining in-depth understanding is a long process that takes
understanding process operation and software engineering. From the ISA and
InTech.
Getting
Quality down PAT - Baha Korkmaz,
Arnold Martin, and Cenk Undey - Companies that proactively approach the
new technological trends and invest in automation have a better chance of
success. Using the concepts behind process analytical technology (PAT) is one
effective tool to achieve this success, especially when incorporating batch
standards, such as ISA88. From the ISA and InTech.
Brewery
Taps Higher Control - Small brewer’s system allows
greater productivity, flexibility - John Mallett and Todd Stauffer - When
Bell’s Brewery decided to upgrade the temperature control system on its 45
fermentation tanks in mid-2006, they were just planning on expanding their
existing system of dedicated single-loop controllers for each of its tank
control points. Instead, after taking a look at their options and what
technology suited them best, Bell’s opted to take a quantum leap forward by
implementing a state-of-the-art process automation system for temperature
control of its tanks.
Cascade Control
Cascade
Control- Handle Processes that Challenge Regular PID Control -
Arthur Holland, Holland Technical Skills- A paper which explains how Cascade
Control can be used to cater for lags in Process Control.
Cascade
Control - The Basics - from learn control.com
Compressor Surge Control
Compressor
Surging Under Control - Turbocompressors, either centrifugal
or axial, are the heart of many industrial processes. Often, these
compressors are critical to the operation of the plant, yet they are seldom
installed with a spare unit. Surging represents a major threat to
compressors and these processes. Surge prevention is an important process
control problem in these environments as surging can result in costly downtime
and mechanical damage to the compressors. An effective anti-surge control
system is critical for every turbocompressor. From Prabhat Yadav and
Cheresources.com
Control Room Design
The following really good papers by Ian Nimmo are available
from mycontrolroom.com
-
Don’t be thrown for a loop - Ian Nimmo and John Moscatelli, describing
impacts on a console operator’s workload. This paper recommends the best
methodology and operating procedures for determining proper staffing levels
based on job complexity, loop count, process disturbances, and graphics.
- Designing a control building - discusses major
aspects to designing a new control building i.e., building location, standards,
selecting an architecture firm, building company, console layout and ergonomic
considerations, people changes and management of change.
- Mandated Human Error Controls in USA-discusses
a new approach to safety breaking the traditional barriers of people,
organizations and culture, and puts control engineer back in the driving seat
for determining performance improvements, optimizing control algorithms, people,
and the way they interface with technology.
- Operator Consoles - Growing Old Together -discusses refurbishment projects and
best methodologies and standards for making the changes such as Study of
Management Systems, i.e., people and performance systems; Ergonomic Design of
Operating desks or Consoles; Human Computer Interface, Alarm Management, and
Design of Control Rooms.
- Putting a human face on the design of Control
Rooms -discusses how technology has pushed Industrial processes to the limit,
and why Companies should implement standards and best practices around factors
such as human related incidents and Control Room Design.
- Designing Control Rooms for Humans - Ian Nimmo
and John Moscatelli - discusses today’s work environment and how it has been
revolutionized by PC’s and PC workstations.
Control System Forums
Control
System Forum moderated by Jamie Ross.
Fuzzy
Logic - Looking to find more on
Fuzzy Logic? Find it at ICEweb's Fuzzy Logic page.
Modbus -
A link to some useful Modbus technical information.
What is
Proportional, Integral and Derivative Control? - A Tutorial Overview (An
excellent technical document from Expertune)
Decentralised Control
Frequently
Asked Questions - From SEW Eurodrive and
Automationworld.com
Pneumatic Controllers
Fundamentals
of Pneumatic Controllers -Doug Butler -
Controllers in one form or another have been around the process industries for
a number of years. In fact, they are such a familiar sight in most industrial
operations that they frequently suffer from being taken for granted. Yet, the
quality of performance provided by a control system is determined by the
performance of the controller and the other elements in the loop. The
controller, with its various adjustments, is the one element in the control
loop that allows any measure of operating flexibility. For optimum
performance, it is necessary to use the controller properly. This requires a
thorough understanding of some fundamental relationships - From CEESI
Process
Sequence Control Documentation Standards
ISA
has a number of standards in this area, the most well known of which is the
ISA-88 batch standard. ISA also has a number of books on this same topic
Programmable
Automation Controllers
PACs
for Industrial Control, the Future of Control - With a
number of vendors producing Programmable Automation Controllers that combine
the functionality of a PC and reliability of a PLC, PACs today are
increasingly being incorporated into control systems. This white paper
explores the origins of the PAC, how PACs differ from PLCs and PCs, and the
future direction of industrial control with PACs - From National Instruments.
Programmable
Logic Controllers -Useful technical information on PLC,s
On-Line
Process Control Tutorials - Some
super tutorials and papers (from expertune -www.expertune.com)
Loop Tuning
Tune
Guide. A Free Controller Tuning and Documentation Program -
Patrik Johansson
Tuning
a PID Controller-From the University of Exeter
The following technical articles are links from
the excellent publication ControlGlobal.com
- Tuning
a PID Temperature Controller
- Cascade control tuning-
Bela Liptak gives advice
- Special
rules for tuning level controllers (Part-1) F.G.
Shinskey
-
Special
rules for tuning level controllers Part 2
- 15
case-in-points of common control myths-By Greg
McMillan and Stan
Weiner, PE
- PID
loop tuning tips pocket guide-This eight-page publication
from ControlSoft Inc was created to give engineers a short easy-to-use guide to
tuning PID loops, and it includes a reference section that summarizes many of
the more common controllers available.
The following are excellent loop optimisation papers (from
expertune) have a look at their great website
for more super Control System information.
The
Six Most Common PID Configuration Errors: How to Find and Fix Them -
The PID Control Loop is one of the fundamental workhorses of the process
industries. Day in and day out, millions of PID loops strive to keep processes
safe, stable, and profitable. But there is a "secret", known only to
control engineers and technicians. Many of these control loops are not properly
configured, and the consequences could be devastating. Surprisingly, as many as
75% of control loops actually increase variability. Many control loops simply do
not do their job. Setpoints are not followed, valves swing around, creating
oscillations, and many loops are disabled by the operator: placed in MANUAL
mode.Studies of control loops in the process industries give some insight into
the root cause of these issues. For example:
- 30% of DCS Control Loops Improperly Configured
- 85% of Control Loops Have Sub-Optimal Tuning
- 15% of Control Valves are Improperly Sized
- Loop
Optimization- Reap the Greatest Benefits
- Steps
to optimise your control loop
- Loop
Optimization- Troubleshooting
-Loop
Optimization- How To Tune A Loop
- Learn
How To Assess And Improve Control Loop Performance
-Prioritising
and Optimising Problem Loops Using a Loop Monitoring System
- A
practical approach for large-scale controller performance assessment,
diagnosis, and improvement
- Poor
Controller Tuning Drives Up Valve Costs
11.09Improving
PID Controller Performance - Proportional integral derivative
(PID) control is the most commonly used control algorithm in the industry today.
PID controller popularity can be attributed to the controller’s effectiveness
in a wide range of operation conditions, its functional simplicity, and the ease
with which engineers can implement it using current computer technology. This
paper covers some of the PID drawbacks and how to resolve them while improving
performance in current implementations through changes in the algorithm - from
National Instruments.
12.09
Tuning
the Forgotten Loop - We can tune PID controllers, but what about tuning the
operator? - Steve Rubin - The purpose of tuning loops is to
reduce errors and thus provide more efficient operation that returns quickly to
steady-state efficiency after upsets, errors or changes in load.
State-of-the-art manufacturers in process and discrete industries have invested
in advanced control software, manufacturing execution software and modeling
software to “tune” everything from control loops to supply chains, thus
driving higher quality and productivity. The “forgotten loop” has been the
operator, who is typically trained to “average” parameters to run adequately
under most steady-state conditions. “Advanced tuning” of the operator could
yield even better outputs, with higher quality, fewer errors and a wider
response to fluctuating operating conditions. This paper explores the issue of
improving operator actions, and a method for doing so.
Other Useful Information
The
following excellent papers on Controlling Equipment have been made available by Walter
Driedger as a service to other engineers, find them at http://www.driedger.ca/
- Controlling Centifugal Pumps
- Controlling Positive Displacement Pumps
- Controlling Shell and Tube Heat Exchangers
- Controlling
Steam Heaters
- Controlling
Fired Heaters
- Controlling
Vessels and Tanks
- Connecting and Interpreting Limit Switches
- Optimum Settings for Automatic
Controllers- By
J.G. Ziegler and N. B. Nichols, Rochester, N. Y.
Process Control Security
- ICEweb's
Security Page has a very comprehensive range of articles and papers.
Process
Control System Ergonomics - Papers required on Hardware Ergonomics and Graphic
Design, please submit here.
OPC
- OLE for process control (which stands for Object Linking and Embedding (OLE)
for Process Control).
OLE
for Process Control (OPC) Overview - This paper provides an overview
of the OPC standard and discusses the benefits of OPC for vendors and end users.
Thanks to our sponsor Emerson Process Management.
OPC
Communications - Stephen Mueller/ Dean McNair - OPC (OLE for process
control) is the modern standard of choice for establishing seamless open
communications between the plant and enterprise levels in today’s industrial
process applications. OPC technology is implemented where end users choose to
maintain an open, non-proprietary communication philosophy within their
businesses thereby ensuring freedom of choice, the power to negotiate
commercially and the ability to choose best-in-class technology. Since the first
release of OPC standards in 1996, this emerging technological development has
come of age and interfacing over ethernet via OPC technology today presents a
cost effective, reliable and straightforward alternative to aging serial
communications protocols or restrictive proprietary communications networks.
3.10
OPC
Communications - Stephen Mueller/
Dean McNair
- OPC (OLE for process control) is the modern standard of choice for
establishing seamless open communications between the plant and enterprise
levels in today’s industrial process applications. OPC technology is
implemented where end users choose to maintain an open, non-proprietary
communication philosophy within their businesses thereby ensuring freedom of
choice, the power to negotiate commercially and the ability to choose
best-in-class technology. Since the first release of OPC standards in 1996, this
emerging technological development has come of age and interfacing over ethernet
via OPC technology today presents a cost effective, reliable and straightforward
alternative to aging serial communications protocols or restrictive proprietary
communications networks.
Thanks to our sponsor Hima
Australia.
MatrikonOPC
have a heap of useful information on their site on OPC (you have to register but
it is worth the effort) , this includes tutorials,and
papers
which provide a great start in understanding OPC.
OLE
for Process Control - A description from Wikipedia
A
number of OPC papers are available from the OPC foundation website.What
Is OPC? - OPC (OLE for Process Control) is a standard interface between
numerous data sources, including devices on a factory floor, laboratory
equipment, test system fixtures, and databases in a control room. To alleviate
duplication of effort in developing device drivers, eliminate inconsistencies
between drivers, provide support for hardware feature changes, and avoid access
conflicts in industrial control systems, the OPC Foundation defined a set of
standard interfaces that allow any client to access any OPC-compatible devices.
Most suppliers of industrial data acquisition and control devices work with the
OPC Foundation standard. From National Instruments.