08-16-2017, 10:47 PM
SCADA
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Traditional Control 2nd
Dedicated Consoles
Point to point communication
No network
No remote access
No remote diagnostic
Distributed Control 2nd
Advantages:
Distributed databases/ programs created from a single development environment (also in front end processor)
Distributed access
Distributed diagnostic
Display everything everywhere
Disadvantages:
None of the DC systems are compatible to each other
Difficult:
Integration of various field bus components
What, Where and Why
What is SCADA and where is it used
Supervisory Controls And Data Acquisition
Application area :
Industrial processes: chemical, power generation and distribution, metallurgy,
Nuclear processes: reactors, nuclear waste, ..
Experimental physics: Tokamaks, HEP laboratories
Application size:
20 K I/O to 450 K I/O, two examples of 1 M I/O under development
Why SCADA systems were evaluated for LHC SLC ?
Reduction of resources
CERN policy of outsourcing
What do SCADA Provide?
Flexible and open architecture
Basic SCADA functionality
MMI
Alarm Handling and Trending
Access Control
Automation
Logging, Archiving, Report Generation
Interfaces to H/W and S/W
Interfaces to ERP- and Expert-Systems
Development Tools
SCADA functions (2)
Alarm Handling
Based on limit and status checking *
More complicated expressions developed by creating derived parameters *Alarms are time stamped and logically centralised *
Notifications (audible, visual, Email, GSM)
Multiple alarm priority levels
Grouping of alarms and handling of groups is possible
Suppression and masking of alarms either individually or as a complete group
Filtering of alarms is possible
SCADA functions (3)
Trending
Multiple trending charts
Charts are pre-defined or configured on-line
Charts contain multiple pens,
Zooming, scrolling, panning, Hairline
Real-time and historical trending
Write data to RDB
SCADA functions (4)
Access Control
Users organised in groups with a set of allocated privileges
Large number of groups possible
Privileges limit write access to process parameters
Some allow access to graphics and functionality to be limited
Automation
Actions can be initiated automatically triggered by an event *
Recipes
Sequencing and scripting possibilities
SCADA functions (5)
Logging, Archiving
Data stored in compressed and proprietary format
Logging / Archiving either for a set number of parameters or for a set period of time
Logging / Archiving can be frequency or event driven *
Logging of user actions together with a user ID
VCR facility for playback of stored data
Writing logs into RDB
Report Generation
Reports created using SQL type queries to the RTDB or logs
Automatic generation, printing and archiving of reports
Use of components for report generation
Interfaces to H/W and S/W
H/W
Multiple communication protocols supported in a single system (in particular CERN supported Field busses)
Support for major PLCs/DCSs but not VME
S/W
API
ODBC, DDE and OLE I/F to PC Products
OPC Client and OPC Server
ActiveX Containers
Web clients
Development Tools
Project editor
Graphics editor
Configuration through parameter templates
Scripting language
Most processing tools based on IEC 1131
Batch configuration according to S88.1
Driver Development Tool Kit
Evolution
Frequent new versions
From tag/ channel-based to device oriented
Multi-team development
Web technology, Active X, Java, etc.
OPC for internal communication
Etc
Benefits of SCADA
Standard frame for application
Rich functionality (50 - 100 p-yrs investment)
Reliability and Robustness (very large installed base, mission critical processes)
Limited specific development
Technical support and maintenance
.. Etc
Data Access Mechanism's
Alarm Server typically poll data from the data server
( -> impact on network bandwidth)
More advanced techniques like publish / subscribe are available in some cases
Data from field buses are mainly polled
Asynchronous protocols are difficult to handle
DESY Experience 1st
Namespace
Individual tags for each property blow up the namespace
Flat namespaces of thousands of tags can not be properly handled without adequate tools
Latest SCADA technology clearly shows the trend to support the definition of objects which cleans up the namespace
System Load
Additional non standard- features like
calculating alarms for each channel
temperature conversions ( 6th grade polynomial)
.. can cause a lot of overhead which needs to be taken into account for the calculation of the system load on process controllers ( here: in a SCADA-like DCS system)
DESY Experience 2nd
Project Management
Small systems can be easily handled with in-house personal
Big systems (several thousand of channels) should be coordinated by an engineering office because of:
The coordination of the Field Bus (PLC) databases and the SCADA databases
The knowledge of the various tools which come along with a SCADA system
One of the main arguments for SCADA systems is: outsourcing
Let s go for it ! ???
Utility controls @ DESY use EPICS as a SCADA system
H1 is going to use PVSS for their slow controls
There s no alternative for big projects like TESLA
Various subsystems can be controlled by SCADA systems:
Utility Controls (water, energy, air, heating..)
Cryogenic Controls (cryogenic plants, cryogenic distribution)
Vacuum Systems (insulation vacuum, beam vacuum)
Special developments i.e. for RF control should have a SCADA-aware design
Is SCADA the only Future ? ..
New Technology: JetWeb
Each node is an individual Web Server
All nodes and all I/O hooked up to the Ethernet