Message-Based Communications for Pipeline SCADA

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Message-Based Communications for Pipeline SCADA
Stephen Koenig, P.E.
Smarter Infrastructure for Oil and
Gas December 3, 2013 Houston, TX
source http//www.epa.gov/gasstar/images/newsroom
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source http//www.welkereng.com/wfms/portfolio/im
ages/pipeline.jpg
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Data stored in the Corporate Accounting System
Data calculated by meter station Flow Computer
Sensor Data
Data stored in the meter station Flow Computer
source http//www.transport4.com/PublicSite/t4pub
licweb/home.aspx
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Messaging - Basic Concepts

• Multiple data sources (publishers) send messages
  to multiple data destinations (subscribers)
• Destinations subscribe by topic
• Payload can be anything text, binary, fixed
  fields, etc up to 250Mbytes in size
• Broker supports multiple delivery options (QoS)

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Automation to SupportPipeline Operations
Tank Gauging System
Flow Computer
Remote Terminal Unit
Comm Processor
Satellite Link to Control Center
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source http//www.northerngateway.ca/assets/498x2
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source API RP 1165 Recommended Practice for
SCADA Displays
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Traditional Approach to SCADA Poll/Response

• Host RTUs are serial devices typically
  Programmable Logic Controllers
• Round Robin polling
• Data format optimized for mininimum overhead

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Problems with Poll/Response systems

• Host owns communications link
• Dedicated circuits are too expensive
• Alarm latency increases with RTU count

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Evolution to Message-Based Communications Step 1
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Evolution to Message-Based Communications Step 2
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Evolution to Message-Based Communications Step 3
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Evolution to Message-Based Communications Step 4
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Challenges in Use of Message-BasedCommunications
for SCADA

• Controls limited life in system
• Stale Data replace poll/response functionality
  in event-driven system
• Security
• Flexible architecture may result in new
  vulnerabilities
• Message-based system must be as secure as
  traditional poll/response
• Need for continuous improvement

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Benefits of Message-Based Approach to SCADA

• Topic/Payload Message Structure
• IP Routing
• Intelligent Front-End Processor
• Many-to-Many Architecture

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Benefits - Topic/Payload Message Structure

• Wildcard subscriptions
• Support for multiple applications on one message
  broker
• Use of version number in topic
• Facilitate prototype and test of new clients
• Allows site-by-site migration strategy

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Benefits IP Routing Scalability
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Benefits IP Routing -- Redundancy Reducing the
Impact of Failure
Broker1 Broker2 Broker3 Broker4

• Provisions for broker equipment failure
• Provisions for loss of primary communications
  link backup link

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Benefits Intelligent Front-End Processor
Broker1 Broker2 Broker3 Broker4

• Adapt Serial Devices to IP/VSAT
• Move polling/response to field
• Ability to handle multiple RTU protocols
• Local intelligence can supplement or enhance
  control system

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Benefits Many-to-Many Architecture

• Significantly reduced project schedules
• Off-line systems receive live data for testing

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Future Opportunities for Message-Based SCADA
Systems(from a 2005 perspective)

• Flight Simulator for pipeline Controllers
• Interface to business systems
• Real-time meter ticket transactions to shippers
  and other carriers business systems
• Distributed SCADA