POWER FACTOR IMPROVEMENT BY AUTOMATICALLY ENGAGING APPROPRIATE

NUMBER OF SHUNT CAPACITOR FOR INDUCTIVE LOADS

Under the Guidance of:

Submitted by: 1)SHITOLE SANKET SUBHASH

INTRODUCTION

In the present scenario of technological revolution it has been observed that the power is very precious. The industrialization is primarily increasing the inductive loading, the Inductive loads affect the power factor so the power system losses its efficiency. There are certain organizations developing products and caring R&D work on this field to improve or compensate the power factor. The Automatic Power factor Correction device is a very useful device for improving efficient transmission of active power. Automatic Power factor correction device reads the power factor from line voltage and line current, calculating the compensation requirement switch on different capacitor banks.

WHAT IS POWER FACTOR

Power factor is the ration between the KW and the KVA drawn by an electrical load where the KW is the actual load power and the KVA is the apparent load power. It is a measure of how effectively the current is being converted into useful work output and more particularly is a good indicator of the effect of the load current on the efficiency of the supply system.

In industry most of the load is inductive in nature which results in lagging power factor that is why there is loss and wastage of energy which results in high power bills and heavy penalties from electricity boards. If the load is uneven it is very difficult to maintain unity power factor. To overcome this difficulty APFC panel is used which maintains unity P.F.

Why APFC are required:

MICROCONTROLLER (AT89S52)

RELAY

RELAY DRIVER

LCD

CURRENT TRANSFORMER

INDUCTIVE LOAD

SHUNT CAPACITOR

PUSH BUTTONS

LED

RESISTOR

CAPACITOR

HARDWARE COMPONENTS

POWER SUPPLY

230 V AC 50 Hz

5V DC

12V step down transformer

Filter(470µf)

5v RegulatorBridge rectifier

MICROCONTROLLER

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

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 RxDP0 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

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

RELAY DRIVER (ULN 2003)

ULN2003 is a high voltage and high current Darlington transistor array

It consists of seven NPN Darlington pairs that feature high-

voltage outputs with common-cathode Clamp diode for

switching inductive loads.

The ULN2003 has a 2.7kW series base resistor for each

Darlington pair for operation directly with TTL or 5V

CMOS devices.

Current, Output Max:500mA

Voltage, Input Max:5V

Voltage, Output Max:50V

Fig: ULN 2003

QUAD VOLTAGE COMPARATOR LM339● Wide single supply voltage range 2.0VDC TO 36VDC or dual

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

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.

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)

SOFTWARE 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.

ADVERSE EFFECT OF OVER CORRECTION

Power system becomes unstable

Resonant frequency is below the line frequency

Current and voltage increases

ADVANTAGES OF IMPROVED POWER FACTOR Reactive power decreases Avoid poor voltage regulation Overloading is avoided Copper loss decreases Transmission loss decreases Improved voltage control Efficiency of supply system and apparatus

increases

CONCLUSION:

It can be concluded that power factor correction techniques can be applied to the industries, power systems and also house holds to make them stable and due to that the system becomes stable and efficiency of the system as well as the apparatus increases. The use of microcontroller reduces the costs. Due to use of microcontroller multiple parameters can be controlled and the use of extra hard wares such as timer , RAM,ROM and input output ports reduces.

REFERENCES P. N. Enjeti and R martinez, “A high

performance single phase rectifier with input power factor correction ,”IEEE Trans. Power Electron..vol.11,No.2,Mar.2003.pp 311-317

“The 8051 Microcontroller and Embedded Systems” by Muhammad Ali Mazidi and Janice Gillispie Mazidi.

Data sheet of micro controller AT89S52 by ATMEL CORPORATION

THANKYOU