16-05-2013, 04:19 PM
SUBSTATION AUTOMATION
SUBSTATION.pptx (Size: 724.35 KB / Downloads: 46)
Introduction
Demand of Electric power is increasing
Demand should be met with advanced protection
A close look on substation parameters is essential
Distribution efficiency should be high
An embedded design is formulated for protection
Act as intelligent interface between substation and distribution system
OBJECTIVES
Integrated monitoring of substation parameters
Reduce human interaction
Optimum maintenance of substation parameters
Improve reliability
TASKS TO BE PERFORMED
Voltage sensing
Current sensing
Frequency sensing
Temperature monitoring
Transformer oil level control
Reactive power management
Different station notification under fault
Operation
Voltage is sensed from the LV side of transformer and given to channel 1 of CPU
Current measured by CT is given to channel 2 of CPU
Frequency measured is fed to the CPU
Temperature is sensed and given to channel 3 of CPU
Transformer oil level indication is fed to CPU
All the decision making is done by the CPU
It then sends commands to relays ,Oil valve and buzzers
All fault events are notified to various stations using GSM
PIC 16f877 CPU
High performance microcontroller
Easily programmable
Low power consumption
Includes 10 bit multichannel ADC
Includes seamless USART interface
Includes external interrupts
Low cost
Op Amp Comparator
Output from Opto-coupler is not perfect square pulse
A square pulse is preferable for microcontroller
LM358 op amp is used
Voltage level is compared with a reference voltage
Output goes high when difference between reference and input is positive
Temperature And Oil Sensing Unit
Temperature Sensed using LM35 temperature sensor
It has high accurate and linear output
It gives 10mv/0C output
The output voltage is given to ADC channel
The measured temperature is displayed
The oil level is sensed using an opto-coupler
The indication is given to the microcontroller
Oil level Control
When the opto coupler produces an active low output, CPU senses oil level decrease
It then gives command to operate oil valve
Oil Valve is operated using a gear motor
Valve is opened and closed using L293D Motor controller
Conclusions
An embedded based system is formulated to monitor and control substation parameters
Various parameters are intelligently sensed and controlled
A prototyped system is developed