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© Invensys 00/00/00 Invensys proprietary & confidentialSlide 1
FSRUG MeetingSan Antonio, TexasFebruary 21, 2011
Mike Phillips
Design and Operations Considerations of a Distributed Control System
FSRUG Meeting – San AntonioInvensys Attendees• Mike Phillips – Director Nuclear Marketing• Chris Wiegand – Nuclear Client Executive• Scott Zimmerman – Customer Sales Executive• Tim Frost – Project Engineer• Masud Ahmad – Product Sales Engineer• Daren Zahabizadeh – Technical Sales Consultant• Tony Moreland – NA TSC DirectorParticipating in the Vendors Nights Monday & Tuesday. Look forward to seeing your there.
Distributed Control Systems Discussion Topics• What is a distributed control system
– Why go digital in the first place– What is the difference between a DCS and a PLC– What are the pros and cons of each
• Implementation of Digital Systems– Lessons Learned
• Project Documents / Specifications• SQA and your system• Cyber Security• Service and Maintenance of your system
• Customer Feedwater Solution Overview and Results
Slide 3
Distributed Control Systems Why go digital in the first place?• Obsolescence• Single Point Failure Vulnerability• Maintenance Issues
– Problems maintaining old system– Spares– Original suppliers out of business
• Nuisance Plant Trips / Startup delays• Tribal Knowledge / Plant “As Builts”• Multiple platforms and vintage• Workforce attrition
Slide 4
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Distributed Control Systems
Plant Computer &
Data Acquisition
Potential Upgrade
Applications
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Distributed Control Systems
Plant Computer &
Data Acquisition
Potential Upgrade
Applications
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Wikipedia:
A distributed control system (DCS) refers to a control system…..in which the controller elements are not central in location (like the brain) but are distributed throughout the system with each component sub-system controlled by one or more controllers. The entire system of controllers is connected by networks for communication and monitoring. DCS is a very broad term used…….to monitor and control distributed equipment.
Distributed Control Systems
Plant Computer &
Data Acquisition
Potential Upgrade
Applications
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Distributed Control Backbone
Distributed Control Backbone
Distributed Control Systems - PLC
Plant Computer &
Data Acquisition
Potential Upgrade
Applications
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PLC
HMI
A programmable logic controller (PLC) or programmable controller is a digital computer used for automation of electromechanical processes. The PLC is designed for multiple inputs and output arrangements, extended temperature ranges, immunity to electrical noise, and resistance to vibration and impact.PLCs may include logic for single-variable feedback analog control loop, a "proportional, integral, derivative" or "PID controller". Historically PLCs were usually configured with only a few analog control loops. Where processes required hundreds or thousands of loops, a distributed control system (DCS) would instead be used. As PLCs have become more powerful, the boundary between DCS and PLC applications has become less distinct.
Distributed Control Systems DCS & PLCs: What are the pros and cons of each?• DCS PROs
– DCS gives you a plant backbone and the built in capacity to distribute controllers and expand the system in the future.
– Single platform for the plant... learn and maintain ONE platform, the only difference in the “distributed controllers” is the application configuration
– Higher level built in configuration tools. Wider range of control algorithms– On-line repair and self calibration (may decrease surveillances)
• DCS CONs– Non-DCS HMI solutions can provide more flexibility in developing application
specific graphics– Longer Outage time and Higher cost of installation– Non-safety rated and no triple redundancy offering
Slide 9
Distributed Control Systems (PLC’s) DCS & PLCs: What are the pros and cons of each?• PLC PROs
– Allows an “islands of automation” approach to plant upgrades– Triple Modular Redundancy (TMR) for “Production Critical” applications– On-line repair and self calibration (may decrease surveillances)– PLC Speed response times– Ladder Logic, Function Block, and Structured Text programming languages– Single, Dual, & Triplicated options
• PLC CONs– Limited set of predefined Algorithms (but can be developed)– Need to build communications infrastructure– Utilizes Non-DCS packages for HMI graphics
Slide 10
Distributed Control Systems So, do I use a DCS or a PLC?But first, what is the reason for considering a digital
upgrade and what is the overall objective?• Are you considering a plant wide digital solution?• Do you have a digital upgrade plan in place for your facility?• Solving a nagging maintenance issue with no future digital
plans? • Capturing operational knowledge?• Looking for a common platform for BOP systems• Is there a specific SQA Level required?• Maybe we should look at lessons learned……..
Slide 11
Digital Systems - Lessons Learned
Specifications
• Educate your team on what is possible• Define the functionality you will require in your system• At a minimum - develop a good I/O list to include in the specification. Result?
• More accurate proposals from the vendors• Will get the project off on the right foot
• Clearly identify vendor documentation requirements• Avoid the “Kitchen Sink” approach when listing Codes and Standards
• Increases the risk factor to the vendor & increases cost • Penalized by Purchasing
• Determine the level of SQA that will be required. Make sure you understand your requirements so you can explain it to the vendor• Example: Applying typical 1E requirements to a non 1E class system
Slide 12
Implementation of Digital Systems Specifications
• Give yourself time to write a good specification • Make sure the schedule is realistic
• Un-realistic schedules increase pricing…..somewhere along the line• Don’t forget about the Simulator Upgrade
• Should have a strong focus since it is usually the first to be implemented• Are there plant standard devices? Encourage vendor to incorporate
but be flexible to vendor options• Network Switches• Field Transmitters
Slide 13
Picking a Supplier
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• Experience, Experience, Experience• All Experience, not just Nuclear• “Production Critical” projects especially• Vetted Project Procedures and SQA Plan
• Experience with a variety of Nuclear Plant Digital I&C Projects
• Does the supplier have a strong history of product support and a strong migration path• Past performance is an indication of the future performance• Be wary of installing “one off” or obsolete equipment!• Know what you are getting and get involved
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Picking a Control System Platform• Experience, Experience, Experience• Will the platform lend itself to previous plant digital upgrades?• Open or closed type of architecture• Does it fit into the Plant Standardization philosophy?• Is the Platform Fault Tolerant?• Is the system a COTS Technology and used in other industries
• Knowledge of processes• Data base of reliability data• Economies of scale• Longer term support from vendor
• Ask the question how will we maintain the system ourselves?• Implement a configuration control program • Allows ease of upgrading digital hardware and software • Don’t drive yourselves into DIGITAL OBSOLESCENCE!
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Enhancements• Elimination of Single Point Failures• Ease of Maintenance• Reduction of test frequency of control system• Automation of testing• Additional Information available to operations
and maintenance through the Human Machine Interface
• Improved diagnostics of the control system as well as process
• Management of Change Friendly
Project Issues
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• Team for success• Assign the proper personnel for the project and make sure
they have the right attitude toward the project• Design • System Engineering• Operations• Simulator• Maintenance• IT
• Keep the same project team for the duration of the project• Make sure management sees the project as top priority
• Need contractor help for the project? Have the contractor take on day to day plant responsibilities
• Let plant personnel concentrate on the project• THIS IS YOUR FUTURE!
Project Issues
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• Answer the question “Who will own the system?”• If budget allows, include a training system• If schedule will allow, get the system onsite early and try
to “break it”• The vendor you have chosen needs to be flexible to small
additions that come up during the project • Resist scope creep unless you take schedule and cost
impacts into account.• Train Early
– If possible go to training as part of the Control System evaluation
– Train key project personnel early in the project so they have better input during the project
Mechanical & Instrumentation
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• Single Point VulnerabilitiesTo the extent possible, consider duplicating or triplicating critical
system components. These include:• Oil Pumps and Drivers
• Pressure Switches
• Supply Filters
• Header Pressure Transmitters
• Level Transmitters
• Servo Coils
• LVDT’s
• Coolers
IPS Confidential
Quad-redundant Hydraulic Trip Block• Online Testing• Online Repair• No single point of failure• Manifold mounting for
easy installation and repair• Fully instrumented for
automatic testing
Mechanical & Instrumentation
3D Modeling of new assemblies Hydraulic Control Components Panel
Hydraulic and Pump Skids
Human Machine Interface Issues
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• Resist the urge to hold onto the past.• Try to eliminate hard panels whenever possible• If possible, convince operations to not try to duplicate the
hard panels on the HMI
• Information overload• Resist the urge to alarm everything. This can end up
overwhelming the operator. Again use the simulator to work out Human Factor issues.
• Decide where the HMI will be mounted. • Is there spare space? • Can it be mounted where the hard controls were located?• Do you need to get more creative on where and how to
mount the monitors?
Good or Bad?
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Cyber Security Issues
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• Minimize connections between the control network and corporate networks and only then through firewalls and buffers
• Do not connect the control network to the internet
• If possible limit communications to a unidirectional output to the plant computer and plant historian
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Summary• Communications between all parties essential• Be open to what has been done in and outside nuclear• Understand the details of all requirements • Don’t make assumptions• Study lessons learned and truly implement them in your
project• Start small and grow with those successes with open
systems– Too much at once – is a recipe for failure
• Cultural change – the most challenging of them all!• Take ownership its your Future
ABWR Advanced Control Room
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OK, But Where’s the Beef?Digital Control Systems are as good as the planning, expertise of the
people, platform reliability, application capability, SQA, and installation and start-up of the system.
Today’s systems are not just replacements……they are Digital Upgrades Offering:
– Operational philosophy enhancements– improved startup and runtime performance – Significant reduction of unplanned unit trip outages
These advanced control techniques allow: – Less operator required interaction – Automatic control, especially during start-up and shut-down when most unit
trips are caused – The entire control system is more capable of handling normal operation as
well as process upset conditionsSlide 27
Feedwater Upgrade Enhancements• Redundant Sensor Algorithms (RSA)
• Dual Transmitter Input Algorithm• Dual Transmitter Input Algorithm with Arbiter (Voter)• Triple Transmitter Input Algorithm
• Redundant Valve Outputs• Fully Integrated Single Element/Three Element Control Philosophy• Control Element Assembly Position Indication Logic• Incore Flux Monitoring• Calorimetric Monitoring• Sequence of Events Recording• Atmospheric Steam Dump Control• Steam Bypass to Condenser Control
Slide 28
Typical Client NeedReplace an aging existing Feedwater Control System and
Improve Operational Reliability and Availability• Design a digital replacement solution for this critical system • Should address & mitigate future obsolescence • Should incorporate both high reliability and high availability as
inherent attributes• Should allow the plant operator to focus on the plant behavior • Focus the operators attention on monitoring field parameters critical
to running the plant effectively • Allow quick response on performing corrective actions• Integrate the new feedwater control system with the main turbine
controller and the feedwater turbine controller• Remove single point vulnerabilities in the system wherever possible
Critical Feedwater ConsiderationsImportant To Safety Opportunity• Section 7.7 of the SRP, NUREG-0800, indicates increased scrutiny of
certain non-1E systems by the NRC• Reason? Failure of these systems would challenge the plant safety
systemsFeedwater Control is certainly one such application• Feedwater is critical to continuous plant operation• When the feedwater system goes down, the plant goes down• A single component failure causing unscheduled plant outages• Cost of downtime averages $1M / dayChallenge: Provide highly reliable and available digital solution• Improve the operational efficiency of the plant – gain Megawatts!• Decrease downtime and regulatory risk
The Existing SystemThe unit has two steam turbine driven feedwater
pumps • Both pumps are required to function to achieve 100% power• Significant operation risk and concern for any pump loss• Additional Operational Procedures to compensate for risk• In case of a sudden pump loss it is not possible for the
Operator to react quickly enough to prevent a turbine trip.• Recovery from Reactor Trip = 3 days at a total cost of
operation of $5.5M
The Feedwater Control Solution Digital Upgrade was funded for feedwater control including:• Main Feedwater Control Valves• Feedwater Bypass valves• FWP Demand SignalAutomate By-Pass valves operation and integrate operation into
start up and shut down sequence• Control from the control room.Automate control valve surveillance testing• Push button test from the control room• Test time dropped from 2 days to 15 minutes per valveIntegrate control functionality• Seamless communication with the previously upgraded main turbine
controller for start up, shutdown, and runback control.• Automatic demand placed on feed water turbine governors.
The Feedwater Control Solution Provide Improved Operator Awareness• Dual redundant Operator HMI screens for control and monitoring.• Separate large display mounted to provide easily visible chart
recorder screen. Existing chart recorders were removed.Integrated system now automatically responds to
any feed water level changeOn Unit Runback the system can now survive 50%
reduction in Reactor Power without Operator Intervention
• No Operator action required• No Plant Trip
Solution ValueOne mitigated outage Recovered Original InvestmentReduced maintenance costsDeveloped a consultative relationship with the upgrade teamClient is a valued reference and proud of the resultsMaster Services Agreement now in placeFuture Committed Business IdentifiedPositively impacting relationships across the industryThe ultimate “Win - Win” scenarioIncreased Safety Margin, Reduces Operating CostNo Regulatory Oversight$2.2M Savings minimum for each mitigated event
FEEDWATER – Menu Select Screen
Steam Generator 1 & 2 Feed & Steam Flow
FEEDWATER – Valve Control & Chart Recorders
FEEDWATER – Pump Control
Summary: DCS or PLC?Definitions gave us a feel for the differences but very little definition of
where to use one over the other.One seems better for a system with a lot of analog loops and the other
seems better for electro-mechanical high speed applications.One seems better overall if long range digital upgrades have been
scheduled and the other seems more suited to “islands of automation” or stand alone systems
But tie all the islands of automation together and what do you have? A distributed control system.
So after all that, the real answer is……it just depends Use the right platform for the application and utilize “lessons learned”
“Production Critical” / “Important to Safety”– TMR PLC’s Balance of plant – DCS and tie it all together
Slide 39
Please come by our booth for additional information and discussion
Slide 42
Thank you for your attention!
Questions?
