21-03-2011, 03:24 PM
seminar.pptx (Size: 2.13 MB / Downloads: 109)
Supervisory Control and Data Acquisition
Where we may require
• Industrial- manufacturing ,production ,power generation ,fabrication and refining.
• Infrastructure process may include like water treatment and distribution ,electrical power transmission and distribution systems.
• Facility based systems.
System Components
• Human Machine Interface
• Supervisory computer system
• Remote Terminal Units or Programmable Logic Controller
• Communication infrastructure
Data Acquisition
• Sensors measures Inputs and Outputs to the system.
• Sensors called DI/DO measures the direct digital ON/OFF values.
• There may be some analog sensors for some exact readings for example values of temperature
Data Communication
• Earlier–Radio, Modem or dedicated serial lines.
• Today-Ethernet and IP.
• For security reasons data is send in closed LAN/WAN’s not in open internet.
• GSM antennas and CDMA systems are installed at the physical locations.
• Data Presentation
• Computer stations variously called as master station.
• Humane Machine Interface.
Control
• Full computerized control of SCADA master unit.
• Operator just need some mouse clicks to control any unit which are in turn controlled be the receiving RTU’s.
• Sophisticated master unit controls can run completely automatically.
• Another example from my summer training
Architectures
• First Generation-Monolithic
• Second Generation-Distributed
• Third Generation-Networked
First Generation
• Computing done by mainframe systems.
• No network’s existed therefore SCADA systems were independent systems with no connectivity to other systems.
• Communication protocols often proprietary.
• Redundant as a backup mainframe has to be used.
Second Generation
• Multiple stations were connected through LAN
• Task specific stations thus reducing costs and size .
• Communication still proprietary based.
• Security was a big problem.
Third Generation
• Open architecture rather vendor-controlled proprietary based.
• Internet Protocols used for communication.
• GSM and CDMA’s are installed.
Benefits
• PID control continues even if communications to the main computer lost.
• System compatible with any further installation.
• Provide on board statistical and mathematical processing.
Area of concern
• The security and the vulnerability of the whole system through cyber-crime is the priority area of concern and the work in this direction is being considered.