23-04-2011, 10:23 AM
Presented By:-
Khustar Alam
Malik sameeullah
Manish Kumar
Manish Kr. Bisherwal
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Introduction
In past, human was the main method for controlling a system.
More recently electricity is used for control and earlier electricity control is based on relays.
The development of low cost computer has brought the most recent revolution.
PLC is a work house of industrial automation.It is important because all production process go through a fixed repetitive sequence of operation that involve logic step and decision.
Used to control time and regulate the sequence.
Need Of PLC
Originally a logical control system hard wired using electronic relay, timer and logical unit.
These system is inflexible.
If need to alter machine configuration then logic system is need to be manually rewired for new application.
This was inflexible and time consuming.
History
In 1970,when mini computers become available.
It is easy to perform switching time delay ad logic in computer program.
To reduce complexity, PLC is developed.
In 1980, with the invention of chip and memory, modern PLC is invented.
Application For PLC in Service Automation
There are many application:
Protection And Control
circuit breaker lockout.
protection relay interface
Automatic Switching
Emergency load shedding.
Feeder automation and fault recovery.
Voltage Regulation Management
Load tap changer control.
Voltage regulation control.
Capacitor control.
Station HMI/Graphical user Interface(GUI)
Interactive real time signal line display.
One line operation and maintenance logic.
Type Of Programming
Ladder Logic (LAD) is a graphical representation of the programming language. The syntax for the instruction is similar to a relay ladder logic diagram.
Statement List (ST) is a textual representation of programming language similar to machine code.
Structure Control Language (SCL) is a PASCAL like programming language which is more suitable for creating complex function.
Ladder Program Basic
The main program in PLC is in LADDER LOGIC. Let us take the following example
represents coil protection.
-I I- represents energize coil switch.
Zones Of Control
Zone 1: Transmission Voltage Breaker Bay Control
Zone 2: Transmission Voltage Bus Tripping & Restoration Control
Zone 3: Transformer Control
Zone 4: Sub-transmission Breaker Bay Control
Zone 5: Sub-transmission Voltage Bus Tripping & Restoration Control
Typical Architecture
The Sequence Of Event Recording (SER) application verifies the protection and control scheme in the event of system operation and allows utility operators to fine- tine the model to further increase system reliability.
Sequence of event recording
Increased systems reliability
Demonstrates the capabilities of a PLC-based solution to perform all application.
Benefits of SER
The benefits of using SER in substation using a PLC-based solution includes:
• Safe and profitable business and operating decisions
• Improved diagnostics
• Ease of Implementation
Recent PLC Detail
Siemens S7 PLC
ABB AC 800M PLC
