DEVELOPING ISLANDING ARRANGEMENT AUTOMATICALLY FOR GRID ON SENSING BAD VOLTAGE OR FREQUENCY

Under the Guidance of

Submitted by

Project Title

ABSTRACTThis paper presents the development of a microcontroller based

islanding detection for grid connected inverter with very simple

under/over voltage and under/over frequency islanding detection

algorithms.

The microcontroller monitors the under/over voltage and under/over

frequency from utility grid and the processed value of voltage and

frequency for turning ON/OFF the relay between a grid connected

inverter and the utility grid.

The project would alternatively use a variable frequency generator

using 555timer for changing the frequency while a standard variac

shall be used to vary the input voltage for achieving the test

conditions as stated above.

EXISTING SYSTEM

PROPOSED SYSTEM

BLOCK DIAGRAM

HARDWARE REQUIREMENTS

POWER SUPPLY

MICROCONTROLLER (AT89S52/AT89C51)

555 TIMER

LM358

LM339

RELAYS

BC547

LIQUID CRYSTAL DISPLAY

LED

IN4007

RESISTORS

CAPACITORS

230 V AC 50 Hz

5V DC

12V step down transformer

Filter(470µf)

5v RegulatorBridge rectifier

It is a smaller computer Has on-chip RAM, ROM, I/O ports...

RAM ROM

I/O Port

TimerSerial COM Port

Microcontroller

CPU

A single chip

CPU

On-chip RAM

On-chip ROM for program code

4 I/O Ports

Timer 0

Serial Port

OSC

Interrupt

Control

External interrupts

Timer 1

Timer/Counter

Bus Control

TxD RxDP0 P1 P2 P3

Address/Data

Counter Inputs

Compatible with MCS®-51 Products

8K Bytes of In-System Programmable (ISP) Flash Memory

Endurance: 10,000 Write/Erase Cycles

4.0V to 5.5V Operating Range

Fully Static Operation: 0 Hz to 33 MHz

256 x 8-bit Internal RAM

32 Programmable I/O Lines

Three 16-bit Timer/Counters

Eight Interrupt Sources

Full Duplex UART Serial Channel

Interrupt Recovery from Power-down Mode

Watchdog Timer

Dual Data Pointer

555 TIMERThe 555 Timer IC is an integrated circuit (chip) implementing a variety of timer and multivibrator applications

The 555 has three operating modes:

•Monostable mode: in this mode, the 555 functions as a "one-

shot". Applications include timers, missing pulse detection,

switches, touch switches, frequency divider, capacitance

measurement, pulse-width modulation (PWM) etc.

•Astable - free running mode: the 555 can operate as an

oscillator. Uses include LED and lamp flashers, pulse

generation, logic clocks, tone generation, security alarms,

pulse position modulation, etc.

•Bistable mode or Schmitt trigger: the 555 can operate as a

flip-flop, if the DIS pin is not connected and no capacitor is

used. Uses include bounce free latched switches, etc.

Pin Name Purpose

1 GND Ground, low level (0 V)

2 TRIG OUT rises, and interval starts, when this input falls below 1/3 VCC.

3 OUT This output is driven to +VCC or GND.

4 RESET A timing interval may be interrupted by driving this input to GND.

5 CTRL "Control" access to the internal voltage divider (by default, 2/3 VCC).

6 THR The interval ends when the voltage at THR is greater than at CTRL.

7 DIS Open collector output; may discharge a capacitor between intervals.

8 V+, VCC Positive supply voltage is usually between 3 and 15 V.

Internal architecture of 555 timer

LM358 (DUAL OPERATIONAL AMPLIFIER)

The LM358 series consists of two independent, high gain; internally

frequency compensated operational amplifiers which were designed

specifically to operate from a single power supply over a wide range of

voltages

Operation from split power supplies is also possible and the low

power supply current drain is independent of the magnitude of the power

supply voltage.

Pin description

1 ) Output 1 2 )Inverting input

3 ) Non-inverting input 4 )VCC-

5 )Non-inverting input 2

6 ) Inverting input 2

7 ) Output 2 8 ) VCC+

LM339( COMPARATOR)

The LM339 consists of four independent precision voltage comparators

The LM339 series was designed to directly interface with TTL and CMOS.

When operated from both plus and minus power supplies, the LM339

series will directly interface with MOS logic where their low power drain is a

distinct advantage over standard comparators.

FEATURES

•Wide single supply voltage range 2.0VDC TO

36VDC or dural supplies ±1.0VDC to ±18VDC

● Very low supply current drain (0.8 ㎃ )

independent

of supply voltage (1.0 ㎽ /comparator at 5.0VDC)

● Low input biasing current 25 ㎁

● Low input offset current ±5 ㎁ and offset voltage

● Input common-mode voltage range includes

ground

● Differential input voltage range equal to the power

supply voltage

● Low output 250 ㎷ at 4 ㎃ saturation voltage

● Output voltage compatible with TTL, DTL, ECL,

MOS and CMOS logic system

● Moisture Sensitivity Level 3

IT IS A ELECTRO MAGNETIC SWITCH

USED TO CONTROL THE ELECTRICAL DEVICES

COPPER CORE MAGNETIC FLUX PLAYS MAIN ROLE HERE

The relay's switch connections are usually labeled COM, NC and

NO:

COM = Common, always connect to this; it is the moving part of

the itch.

NC = Normally Closed, COM is connected to this when the relay

coil is off.

NO = Normally Open, COM is connected to this when the relay

coil is on

BC547 (NPN –Transistor)

The BC547 transistor is an NPN Epitaxial

Silicon Transistor.

It is used in general-purpose switching and

amplification BC847/BC547 series 45 V, 100

mA NPN general-purpose transistors.

The ratio of two currents (Ic/Ib) is called the DC Current Gain of

the device and is given the symbol of hfe or nowadays Beta, (β).

The current gain from the emitter to the collector

terminal, Ic/Ie, is called Alpha, (α), and is a function of the

transistor itself

LIQUID CRYSTAL DISPLAY (LCD)

Most common LCDs connected to the microcontrollers are

16x2 and 20x2 displays.

This means 16 characters per line by 2 lines and 20

characters per line by 2 lines, respectively.

The standard is referred to as HD44780U, which refers to

the controller chip which receives data from an external

source (and communicates directly with the LCD.

LCD BACKGROUND

If an 8-bit data bus is used the LCD will require 11 data lines

(3 control lines plus the 8 lines for the data bus)

The three control lines are referred to as EN, RS, and RW

EN=Enable (used to tell the LCD that you are sending it data)

RS=Register Select (When RS is low (0), data is treated as a command)

(When RS is High(1), data being sent is text data )

R/W=Read/Write (When RW is low (0), the data written to the LCD)

(When RW is low (0), the data reading to the LCD)

SCHEMATIC DIAGRAM

Islanding of grid is connected to inverter which is basically managing two

parameters voltage and frequency

In the program it is so written that the output from 555 timer which is fed to

the MC goes to be low 48KHz or above 52Hz. The corresponding outputs of MC

will go high and which will result in switching “ON or OFF” a load to indicate

that the islanding has taken place. (for frequency concerned).

As per the voltage is concerned we have taken 2 comparators. Both the

comparators are given to i.e., one for inverting input and other for non-

inverting input which are given at a particular voltage.

This program is that in either of these cases whether the few is low / high (or)

it could be either in high / low condition the duration will be 50, 49, 48 06

greater than 52.

All these 3 condition’s are taken by the MC and displayed in LCD

Working of project

Keil an ARM Company makes C compilers, macro assemblers, real-

time kernels, debuggers, simulators, integrated environments,

evaluation boards, and emulators for ARM7/ARM9/Cortex-M3,

XC16x/C16x/ST10, 251, and 8051 MCU families.

Compilers are programs used to convert a High Level Language to

object code. Desktop compilers produce an output object code for the

underlying microprocessor, but not for other microprocessors.

i.e the programs written in one of the HLL like ‘C’ will compile

the code to run on the system for a particular processor like x86

(underlying microprocessor in the computer).

For example compilers for Dos platform is different from the

Compilers for Unix platform  So if one wants to define a compiler

then compiler is a program that translates source code into object

code.

“The 8051 Microcontroller and Embedded systems” by

Muhammad Ali Mazidi and Janice Gillispie Mazidi , Pearson

Education.

ATMEL 89S52 Data Sheets.

www.atmel.com

www.beyondlogic.org

www.wikipedia.org

www.howstuffworks.com

www.alldatasheets.com

QUERIES ?

THANKYOU