Project Title DEVELOPING ISLANDING ARRANGEMENT AUTOMATICALLY FOR GRID ON SENSING BAD VOLTAGE OR FREQUENCY Under the Guidance of Submitted by

ABSTRACT This 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.

BLOCK DIAGRAM

HARDWARE REQUIREMENTS POWER SUPPLY MICROCONTROLLER (AT89S52/AT89C51) 555 TIMER LM358 LM339 RELAYS BC547 LIQUID CRYSTAL DISPLAY LED IN4007 RESISTORS CAPACITORS

POWER SUPPLY Bridge rectifier 5v Regulator 230 V AC 50 Hz 5V DC Filter(470µf) 12V step down transformer

It is a smaller computer Has on-chip RAM, ROM, I/O ports... MICROCONTROLLER It is a smaller computer Has on-chip RAM, ROM, I/O ports... RAM ROM I/O Port Timer Serial COM Port Microcontroller CPU A single chip

INTERNAL STRUCTURE OF A MICRO CONTROLLER-AT89S52/51 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 RxD P0 P1 P2 P3 Address/Data Counter Inputs

Features of AT89S51/52 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

Pin Description

555 TIMER The 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.

Internal architecture of 555 timer 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.

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

RELAY 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.

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

Working of project 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

Soft ware Requirements 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.

Applications This project is applicable for Solar Power Plant where frequency varies; frequency and voltage parameters should match with the Power grid.

Advantages The advantage of this project is, it’s secured the Power of the Grid i.e., Power Plants should supply power to the grid rather than drawing the power from the grid.

DISADVANTAGE The disadvantage of this project is, it’s available in single phase supply where power Grid is of Three Phase supply.

BIBILOGRAPHY “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

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