Smart Grid Switching System

The aim of this project is to develop a device that is able to switch and sort different sources connected to the load. This project switches between sources according to the priority given to various incoming sources taking into consideration that which source among the present source is the most economical.
The project can switch between the incoming sources manually also to satisfy the continuously varying load in real world applications.



1.1 Overview
In this project we use four switches to demonstrate the respective failure of that power supply. When any of the source is present it checks the priority and load is connected. A microcontroller of AVR family is used. The output of microcontroller is given to the relay driver IC, which switches appropriate relay to maintain uninterrupted supply to the load. The output shall be observed using a lamp drawing power supply from mains initially. On failure of the mains supply (which is actuated by pressing the appropriate switch) the load gets supply from the next available source, say an inverter. If the inverter also fails it switches over to the next available source and so on. The current status, as to which source supplies the load is also displayed on an LCD. As it is not feasible to provide all 4 different sources of supply, one source with alternate switches are provided to get the same function.
The project can be further enhanced by using other sources like wind power also and then taking into consideration for using the best possible power whose tariff remains lowest at that moment.

1.2 Motivation
The demand of electricity is rapidly increasing day by day, and most of the generation is being done by conventional sources like thermal, hydel etc. As a result of this the demand has superseded the generation. This unbalance between supply and demand has led to frequent power cuts. The need to exploit non-conventional source is necessary to overcome this shortage of power demand.
This project can help in overcoming the above mentioned problems. This project connects multiple sources (Thermal, Wind, Solar, Inverter) at a time with supply. The project with the help of a microcontroller connects the supply to the load according to the programming of the microcontroller. By proper use of programming we can connect the most economical source to the load. Thus this project not only provides uninterrupted power supply but also provides the most economical form of supply thus reducing the electricity bill of the customer.

1.3 Objective and scope of the project
The main objective of this project is to provide uninterrupted power supply to a load, by selecting the supply from any source out of 4 such as mains, wind, Inverter and solar automatically in the absence of any of the source.
The aim of this project is to develop a device that is able to switch and sort different sources connected to the load. This project switches between sources according to the priority given to various incoming sources taking into consideration that which source among the present source is the most economical.
The project can switch between the incoming sources manually also to satisfy the continuously varying load in real world applications.


Basic Working

Opto isolated supply detection: This section isolates the power supply sources from the microcontroller unit using opto coupler IC 4N35, power coming from connector goes into diode to convert the source into DC then using a suitable resistance of about 1k it connects to the internal LED of optocoupler, so when the power arrives the internal LED of opto coupler lit on and in turn the phototransistor switches on providing a ground pulse to the microcontroller unit. This arrangement provides an isolated power sensing to microcontroller.
The current from the 4 different opto couplers is given to the ADC pins of the microcontroller AVR. According to the programming the microcontroller connects the supply to the load in fixed order (priority wise) defined in the code.
The incoming sources is indicated on the LCD screen by 1 & 0’s where 1 indicates an incoming supply whereas 0 indicate absence of the supply
The input to the microcontroller is provided by a separate source through a step down transformer (230V/12V) and then to rectifier and Voltage regulator
The supply from which load is connected is indicated by LED connected.


Hardware Requirements

OPTO ISOLATOR
MICROCONTROLLER (AVR)
TRANSFORMER
VOLTAGE REGULATOR (LM 7805)
DIODES (IN 4007)
LED’s
CAPACITORS
RESISTORS
RELAYS
LOAD
LCD DISPLAY
PCB BOARD
SOLDER IRON
SOLDER WIRE
JUMPER WIRE



software required : KEIL COMPILER

Applications
Power supply can be control in:-
industries
Hospitals
Schools
Multiplexes
Banks etc.

The circuit devised can find applications in numerous conditions where uninterrupted power is required in the most economical form.

This circuit can be used in various manufacturing plants and factories where load varies all day.
The device can be used in houses and buildings to reduce the cost of consumption of electricity by using the most economical form of source for most of the time as long as it is available.
By using power electronic components this circuit can be implemented in sub stations also.
This circuit can be used specially at places where interruption of power cannot be tolerated like at Hospitals.
This circuit provides selection of the most economical power source through proper coding.


Conclusion :

The kit developed was able to switch between the present sources namely wind, solar, battery and mains according to the given priority in which sources are prioritized in the following order
Solar
Wind
Mains
Battery
The kit is provided with a pushbutton by the help of which we can switch among the sources manually also. If we want a certain source to supply power to the load at a particular time of day, we can select the source by pressing the pushbutton.
The current source from which power is being supplied to the load is indicated by an LED located beneath its sign on the LCD.
This kit can manually as well as automatically select a particular source as the mode in which it is working (manual or automatic). In automatic mode the microcontroller selects the most economic source to power the load. The selection of the most economic source depends upon the programming which is selected on the basis of past experience and operator’s judgment.




HAPPY LEARNING !!!