29-06-2012, 03:10 PM
POWER SYSTEM AUTOMATION
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Data Acquisition
Data acquisition refers to acquiring, or collecting, data. This data is collected in the form of
measured analog current or voltage values or the open or closed status of contact points.
Acquired data can be used locally within the device collecting it, sent to another device in a
substation, or sent from the substation to one or several databases for use by operators, engineers,
planners, and administration.
Power System Supervision
Computer processes and personnel supervise, or monitor, the conditions and status of the power
system using this acquired data. Operators and engineers monitor the information remotely on
computer displays and graphical wall displays or locally, at the device, on front-panel displays
and laptop computers.
Power System Control
Control refers to sending command messages to a device to operate the I&C and power system
devices. Traditional supervisory control and data acquisition (SCADA) systems rely on
operators to supervise the system and initiate commands from an operator console on the master
computer. Field personnel can also control devices using front-panel push buttons or a laptop
computer.
Power System Automation
System automation is the act of automatically controlling the power system via automated
processes within computers and intelligent I&C devices. The processes rely on data acquisition,
power system supervision, and power system control all working together in a coordinated auto2
matic fashion. The commands are generated automatically and then transmitted in the same
fashion as operator initiated commands.
I&C System IEDs
I&C devices built using microprocessors are commonly referred to as intelligent electronic
devices (IEDs). Microprocessors are single chip computers that allow the devices into which
they are built to process data, accept commands, and communicate information like a computer.
Automatic processes can be run in the IEDs, and communications are handled through a serial
port like the communications ports on a computer. IEDs are found in the substation and on the
pole-top.
Instrument Transformers
Instrument transformers are used to sense power system current and voltage values. They are
physically connected to power system apparatus and convert the actual power system signals,
which include high voltage and current magnitudes, down to lower signal levels.