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AUTOMATIC POWER FACTOR CORRECTOR USING MICROCONTROLLER

A

PROJECT REPORT

ON

AUTOMATIC POWER FACTOR CORRECTOR

USING MICROCONTROLLER

PREPARED BY: GUIDEDBY

1) Parmar Kevin S. 126370309079 Mr. M. G. Vasava 2) Mehta Vijal B. 126370309082 Ms. V. B. Patel

3) Pancholi Raj K. 126370309086 Mrs. R. P. Ghariya

4) Mirza Ashif A. 126370309089

5) Yadav Amit D. 126370309101

*************************************************************************N. G. PATEL POLYTECHNIC

At.: Isroli, Po. Afwa, Ta. Bardoli, Dist.: Surat- 394620.

Tel.: (02622) 291106 , Mo.: 9228000868, Fax. : (02622) 290488.

ELECTRICAL ENGINEERING DEPARTMENT


Electrical Engineering DepartmentCERTIFICATE

This is to certify that Parmar Kevin S., Mehta Vijal B., Pancholi Raj K., Mirza Ashif, Yadav Amit D.; Pen 126370309079, 126370309082, 126370309086, 126370309089, 126370309101 of Diploma in Electrical Engineering have successfully completed the Term-work of “AUTOMATIC POWER FACTOR CORRECTOR USING MICROCONTROLLER” offered during the academic year October-November 2014.

GUIDED BY: HOD: Mr. M. G. VASAVA Mr. V. K. PATEL

Ms. V. B. PATEL

Mrs. R. P. GHARIYA

PRINCIPAL

(PROF. A. B. SUTHAR)



ACKNOWLEDGEMENT

It is a known fact that words are never sufficient to express the exact amount of gratitude that a person feels but words are the only way we can express our feelings. We would therefore like to express our thanks to our project guide, Mr. M.G.VASAVA for the invaluable guidance, encouragement & kind co-operation extended by him during the term of our project. We would also like to express our gratitude to Ms. M.M.PATEL & Mrs. R.P.GHARIYA for her kind help & guidance towards making our project to this success.

STUDENTS NAME :- ENROLLMENT NO. :- SIGN :-

1) Parmar Kevin S. 126370309079

2) Mehta Vijal B. 126370309082

3) Pancholi Raj K 126370309086

4) Mirza Ashif A. 126370309089

5) Yadav Amit D. 126370309101

ABSTRACT



The thirst for new sources of energy is unquenchable, but we seldom realize that we are wasting a part of the electrical energy every day due to the lagging power factor in the inductive loads we use. Hence there is an urgent need to avoid this wastage of energy.

Before getting into the details of Power factor correction, let’s just brush our knowledge about the term “power factor”. In simple words power factor basically states how far the energy provided has been utilized. The maximum value of power factor is unity. So closer the value of P.F to unity, better is the utility of energy or lesser is the wastage. In electrical terms Power factor is basically defined as the ratio of the active power to reactive power or it is the phase difference between voltage and current. Active power performs useful work while Reactive power does no useful work but is used for developing the magnetic field required by the device.

Most of the devices we use have power factor less than unity. Hence there is a requirement to bring this power factor close to unity. Here we are presenting a prototype for automatic power factor correction using PIC Microcontroller.

INDEX Acknowledgement



Abstract

List Of Figures

List Of Tables

Chapter:-1 Introduction...........................................................01

Chapter:-2 Block Diagram with Explanation.......................... 03

2.1Block Diagram..................................................04

2.2Explanation of Block Diagram……………..…..05

Chapter:-3 Circuit Diagram With Description.......................... 06

3.1 Circuit Diagram………..…………………………07

3.2 Explanation of Circuit Diagram.......................08

Chapter:-4 Components List With Description…………......…11

4.1 LIST Components………….……....………..12

4.2 Components Description……………..….13

4.2.1 PIC16F877A Microcontroller………..13

4.2.2 IC7805……..………………….14

4.2.3 Crystal oscillator

4.2.4 Capacitor…………………………….…..16

4.2.5 Resistor………………………

4.2.6 Diode..............8

4.2.7 Relay…………………………………….19

4.2.8 Current transformer…..……..…………………..20

4.2.9 Potential transformer......................21

4.2.10 LCD…………………………………22

4.2.11 Transistor……………………………...

Chapter:-5 Cost of project…………………………………………………..



Chapter:-6 Advantages, Disadvantages & Application ............................27

6.1Advantages……………….………………………………....…28

6.2Disadvantages……….…………..……………..............…..…28

6.3Application……………….……………………………………28

Chapter:-7 References……………………………………..……………….29

ABSTRACT

The thirst for new sources of energy is unquenchable, but we seldom realize that we are wasting a part of the electrical energy every day due to the lagging power factor in the inductive loads we use. Hence there is an urgent need to avoid this wastage of energy.



Before getting into the details of Power factor correction, let’s just brush our knowledge about the term “power factor”. In simple words power factor basically states how far the energy provided has been utilized. The maximum value of power factor is unity. So closer the value of P.F to unity, better is the utility of energy or lesser is the wastage. In electrical terms Power factor is basically defined as the ratio of the active power to reactive power or it is the phase difference between voltage and current. Active power performs useful work while Reactive power does no useful work but is used for developing the magnetic field required by the device.

Most of the devices we use have power factor less than unity. Hence there is a requirement to bring this power factor close to unity. Here we are presenting a prototype for automatic power factor correction using PIC Microcontroller.

LIST OF FIGURES

SR. NO. CONTENT FIGURE

NO.PAGE

NO.



1 Block diagram of power factor corrector 2.1 04

2 Circuit diagram of power factor corrector 3.1 07

3 PIC16F877A Microcontroller 4.2.1 13

4 IC 7805 Positive voltage regulator 4.2.2 14

5 Crystal oscillator 4.2.3 15

6 Electrolytic capacitor 4.2.4 16

7 Ceramic capacitor 4.2.5 17

8 Resistor 4.2.6 18

9 Diode 4.2.7 19

10 Current transformer 4.2.8 20

11 Potential transformer 4.2.9 21

12 Transistor 4.2.10 22

LIST OF TABLES

SR. NO.

CONTENT TABLE NO:

PAGE NO.

1 4.2.1 14



2 4.2.3 16



CHAPTAR 01:

INTRODUCTION

INTRODUCTION:

This project discusses the need for power factor correction and provides a suitable DIY that could be used for small-scale industries and establishments. When voltage and current are in same phase with each other with an A.C circuits, electrical energy drawn from the source gets fully converted into another form of energy and the power factor is said to be unity.

As the power factor drops, the system becomes less efficient. A drop from unity to 0.9 in the power factor results in 15 per cent more currents requirement for the same load. A power factor of 0.7 requires approximately 43 per cent more current.



In industrial units and establishments, most of the loads are electrical motors and air-conditioning units. These loads are inductive in nature, where the current lags the applied voltage and the power factor is termed as lagging power factor. With capacitive loads, the current leads the voltage and the power factor. The objective therefore should be to neutralise loads by connecting capacitors across the load, which have leading power factor. By improving the power factor you can save money on your electricity bill and also derive the following benefits;

1. Reduction of heating losses in transformers and distribution equipment.

2. Longer equipment life.3. Increase in the capacity of your existing system and equipments.

While power factor correction is required for efficient use of electrical power over correction of power factor correction is not recommended. In this project over correction is not considered; we have considered power factor between 60 per cent and 90 per cent only due to inductive loads.



CHAPTAR 02:

BLOCK DIAGRAM WITH DISCRIPTION

BLOCK DIAGRAM:


POWER SUPPLY

CAPACITOR

BANK

PIC16F877A

MICROCONTROLLER

RELAY

VOLTAGE AND CURRENT STEP

DOWN ARRANGEMENT


Fig.2.1 block diagram

BLOCK DIAGRAM DISCRIPTION:

VOLTAGE AND CURRENT STEP DOWN ARRANGEMENT: In this section we are using current transformer and potential transformer for the step down of voltage and current at a specific value.

BRIDGE RECTIFER & FILTER: Bridge rectifier and capacitor will convert 12 volt A.C. into Pure D.C. voltage because all electronic components will work only on D.C supply.

PIC MICROCONTROLLER: A PIC microcontroller s a small computer on a single integrated circuit containing a processor core, memory, and programmable input/output peripherals. Here it calculate power factor and give signal to operate a relay as per program instruction


LCD DISPLAY

PIC16F877A

MICROCONTROLLER

STEP DOWN TRANSFORMER

BRIDGE RECTIFIER AND

FILTER

5V – 12V REGULATED

POWER SUPPLY

VOLTAGE AND CURRENT STEP

DOWN ARRANGEMENT


REGULATED POWER SUPPLY: Relays will operate only on 12 volt but

other components like LCD, CPU, ADC, will work on regulated 5 volt. so

we have to convert 12V DC to regulated 5V DC Supply.

RELAY: A relay is a switch worked by electromagnet .it is useful if we want a small current in one circuit to control another circuit containing a device such as lamp or electric motor which requires a large current or if we wish several differential switch contacts to be operated simultaneously.

CAPACITOR BANK: It used to improve power factor by connect it in parallel with line. it supply a reactive power in a line for compensating a active power to improve power factor

CHAPTER 3:



CIRCUIT DIAGRAM WITH DISCRIPTION

CIRCUIT DIAGRAM :



Fig.3.1 circuit diagram

CIRCUIT DIAGRAM DESCRIPTION:



Fig..3.1 shoes the circuit of a microcontroller based power factor corrector. The circuit is built around PIC16F877A micro-controller, 230V A.C primary to 9V, 300mA secondary transformer, current transformer, 3 relays, a 16*2 LCD display and few other components. Microcontroller PIC16F877A: Microcontroller PIC16F877A is the heart of the circuit. It is used to detect the phase difference between voltage and current in the A.C mains supply line. It also connects capacitor across the inductive load through a relay as explained below.IC1 is low power high performance. COMS 8 bit microcontroller. Its main features are 8 Kb flash memory, 256 byte EEPROM, 368 byte ram, 33 i/o pins, 10 bit 8 channel analogue to digital converter, three timers, a watchdog timer with its own chip oscillator for reliable operation and synchronous IC interface. IC1’s port pins RBO through RB7 are connected to do through D7 of LCD 1 port pins RD5,RD6 & RD7 of IC1 are connected to control pins resistor select of LCD 1, respectively port pins RC4 through RC6 are use to control relays RL1 through RL3 respectively.In this project, three different PFC capacitors are used to connect across the inductive load through RL1, RL2 & RL3 relays. If power factor is between 60 per cent and 70 per cent RL1 is energized. RL2 is energized if power factor is over 70 per cent but within 80 per cent and RL3 for power factor above 80 per cent but within 90 per cent.When port PIN RC4 of IC1 goes high, transistor T3 conducts and relay RL1 gets energized. This makes a PFC capacitor to connect across the inductive load to neutralise the lagging power factor similarly, PORT PIN RC5 and RC6 can control relays RL2 and RL3 to neutralise the lagging power factor.A 4 MHz crystal oscillator is connected two pins 13 & 14 of IC12 provide the basic clock frequency power on reset is provided by the combination of resistor R1 and capacitor C1. Switch S1 is use for manual reset of the micro controller. Port PINS RA0 & RA1 of IC1 receive the zero crossing detection pulses of voltage and current respectively.

Zero crossing detection. The zero crossing is the instantaneous point in an A.C waveform at which three is no voltage present. In these circuit, two zero crossing detectors are employed to get the phase angle of voltage and current. First zero crossing detector is used for detecting the point where the voltage crosses zero in either direction sinusoidal A.C signals. The mains voltage 230V A.C. is stepped down by transformer X1 to deliver a secondary output of 9V. The transformer output is rectified by full wave bridge rectifier BR1 & applied to the base of transistor T1



through resistor R6. Capacitor C4 charges to its maximum value through diode D4 and provides supply to collector of transistor T1. Zener diode ZD1 regulates the voltage to 5.1V which is suitable for microcontroller input.When rectified output transits through zero, T1 becomes off and its corrector goes high. The detected voltage pulse is applied to port pin RA0 of IC1.Similarly, zero crossing detection for current is done through current transformer X2, bridge rectifier BR2, transistor T2 and zener diode ZD2. The current sample rectifier by bridge rectifier BR2. When rectifier output goes through zero, a pulse is generated an applied to port PIN RA1 of IC1. The time difference between the voltage and the current pulses is calculated by the program embedded in the micro-controller. The power factor value is then calculated and displayed on the LCD. By knowing the value of power factor, we can calculate the value of PFC capacitor required.

PFC capacitor value. For neutralising the inductive reactance, we need to determine the value of PFC capacitor including its kilo-volt-ampere-reactive rating, which need to be connected across the load. There are various methods to determine the corrective reactive power rating. Here we present a very simple method to know the KVAR in two steps:1. Measure the RMS line voltage and RMS line current. Power factor is

already displaying on the LCD. For a single phase system.kW =volts*amps*PF /1000

2. Now determine the corrective reactive power needed for obtaining the desired PF by multiplying the kW value, as found above, with the selected value of PF multiplier from table. For example,if the total plant load is 100kW at 60 per cent power factor. Capacitor KVAR rating necessary to improve power factor to 90 per cent is found by multiplying kW by the 0.849 multiplier in the table which gives 84.9 KVAR or roughly 85 KVAR. The standard PF capacitor rating nearest to 85 KVAR should be used.



CHAPTER: 04LIST OF COMPONENTS WITH

COMPONENTS DETAILS

LIST OF COMPONANTS:

SR.NO COMPONANTS NAME

1 PIC16F877A MICROCONTROLLER



2 CAPACITOR

3 RESISTOR

4 CRYSTAL

5 DIODE

6 RELAY

7 IC 7805 VOLTGE REGULATER

8 TRANSISTOR

9 CURRENT

10 POTENTIAL TRANSFORMAR

11 LCD DISPLAY

12 40 PIN IC SOCKET

Table no.4.1 List of components

COMPONENT DESCRIPTION:

4.1 MICROCONTROLLER :



A microcontroller is a small computer on a single integrated circuit

containing a processor core, memory, and programmable input/output

peripherals. Here we will use the PIC16F877A.

PIC16F877A:

\

Fig.4.1 pic16f877A

PIC 16F877 is one of the most advanced microcontroller from Microchip. This controller is widely used for experimental and modern applications because of its low price, wide range of applications, high quality, and ease of availability. It is ideal for applications such as machine control applications, measurement devices, study purpose, and so on. The PIC 16F877 features all the components which modern microcontrollers normally have.

General Featureso High performance RISC CPU.o ONLY 35 simple word instructions.o All single cycle instructions except for program branches which are two cycles.o Operating speed: clock input (200MHz), instruction cycle (200nS).o Up to 368×8bit of RAM (data memory), 256×8 of EEPROM (data memory), 8k×14 of flash memory.o Pin out compatible to PIC 16C74B, PIC 16C76, PIC 16C77.o Eight level deep hardware stack.o Interrupt capability (up to 14 sources).o Different types of addressing modes (direct, Indirect, relative addressing modes).


http://www.circuitstoday.com/wp-content/uploads/2011/01/PIC-16F877.gif


o Power on Reset (POR).o Power-Up Timer (PWRT) and oscillator start-up timer.o Low power- high speed CMOS flash/EEPROM.o Fully static design.o Wide operating voltage range (2.0 – 5.56)volts.o High sink/source current (25mA).o Commercial, industrial and extended temperature ranges.o Low power consumption (<0.6mA typical @3v-4MHz, 20µA typical @3v-32MHz and <1 A typical standby).

4.2 IC -7805:

7805 is a voltage regulator integrated circuit. It is a member of 78xx series of fixed linear voltage regulator ICs. The voltage source in a circuit may have fluctuations and would not give the fixed voltage output. The voltage regulator IC maintains the output voltage at a constant value. The xx in 78xx indicates the fixed output voltage it is designed to provide. 7805 provides +5V regulated power supply. Capacitors of suitable values can be connected at input and output pins depending upon the respective voltage levels.

Fif.4.2.1 IC 7805

Pin Description:

Pin No Function Name

1 Input voltage (5V-18V) Input2 Ground (0V) Ground



3 Regulated output; 5V (4.8V-5.2V) Output

Features• Output Current up to 1 A

• Output Voltages: 5, 6, 8, 9, 10, 12, 15, 18, 24 V

• Thermal Overload Protection

• Short-Circuit Protection

• Output Transistor Safe Operating Area Protection

4.3 Crystal Oscillator:

Fig. 4.3.1symbol of crystal

The Quartz Crystal Oscillator One of the most important features of any oscillator is its frequency stability, or in other words its ability to provide a constant frequency output under varying load conditions. Some of the factors that affect the frequency stability of an oscillator generally include: variations in temperature, variations in the load as well as changes to its DC power supply voltage to name a few.

To obtain a very high level of oscillator stability a Quartz Crystal is generally used as the frequency determining device to produce another types of oscillator circuit known generally as a Quartz Crystal Oscillator, (XO).

.

4.4 Capacitor: Just like the Resistor, the Capacitor, sometimes referred to as a Condenser, is a simple passive device that is used to “store electricity”. The



capacitor is a component which has the ability or “capacity” to store energy in the form of an electrical charge producing a potential difference (Static Voltage) across its plates, much like a small rechargeable battery.

There are many different kinds of capacitors available from very small capacitor beads used in resonance circuits to large power factor correction capacitors, but they all do the same thing, they store charge.

In its basic form, a Capacitor consists of two or more parallel conductive (metal) plates which are not connected or touching each other, but electrically separated either by air or by some form of a good insulating material such as waxed paper, mica, ceramic, plastic or some form of a liquid gel as used in electrolytic capacitors. The insulating layer between a capacitor plates is commonly called the Dielectric.

4.5 Resistor: A resistor is a two-terminal passive electronic component which

implements electrical resistance as a circuit element.



Fig.4.5.1 resistor fig. 4.5.1 symbol of resistor

When a voltage V is applied across the terminals of a resistor, a current I

will flow through the resistor in direct proportion to that voltage. This constant

of proportionality is called conductance, G. The reciprocal of the conductance is

known as the resistance R, since, with a given voltage V, a larger value of R

further "resists" the flow of current I as given by Ohm's law:

Table No.

4.6 Diode:



Fig.4.6.1 Diode Fig.4.6.2 symbol of diode

In electronics, a diode is a two-terminal electronic component that

conducts electric current in only one direction. The term usually refers to a

semiconductor diode, the most common type today. This is a crystalline piece of

semiconductor material connected to two electrical terminals. the diode is a

device formed from a junction of n-type and p-type semiconductor material.

The lead connected to the p-type material is called the anode and the lead

connected to the n-type material is the cathode. In general, the cathode of a

diode is marked by a solid line on the diode. The primary function of the diode

is rectification

4.7. Relay:

Fig.4.7.1 electromagnetic relay

A relay is switch worked by electromagnet .it is useful if we want a small

current in one circuit to control another circuit containing a device such as lamp



or electric motor which requires a large current or if we wish several differential

switch contacts to be operated simultaneously

4.8 CURRENT TRANSFORMER:

CT is a one type of transformer which is used to measure current. It mostly used in measuring instruments in substation. In this current carrying conductor pass through a circular core which work as a secondary winding and conductor work as primary winding. The Current Transformer ( C.T. ), is a type of “instrument transformer” that is designed to produce an alternating current in its secondary winding which is proportional to the current being measured in its primary.

Fig. 4.8.1 current transformer

Current transformers reduce high voltage currents to a much lower value and provide a convenient way of safely monitoring the actual electrical current flowing in an AC transmission line using a standard ammeter. The principal of operation of a current transformer is no different from that of an ordinary transformer.

4.9 POTENTIAL TRANSFORMER: Potential Transformer is designed for monitoring single-phase and three-phase power line voltages in power metering applications.



Fig. 4.9.1 potential transformer

The working principle of transformer is very simple. It depends upon Faraday's law of electromagnetic induction. Actually mutual induction between two or more winding is responsible for transformation action in an electrical transformer. Faraday's laws of Electromagnet According to these Faraday's law, "Rate of change of flux linkage with respect to time is directly proportional to the induced EMF in a conductor or coil".

4.10 LCD (LIQUID CRYSTAL DISPLAY):

Fig. 4.10.1 LCD display

The values are displayed in the 2x16 LCD modules after converting suitably. The liquid crystal display (LCD), as the name suggests is a technology based on the use of liquid crystal. It is a transparent material but after applying voltage it becomes opaque. This property is the fundamental operating principle of LCDs.

4.11 TRANSISTOR:



Fig. 4.11.1 transistor

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power. It is composed of semiconductor material with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals changes the current through another pair of terminals. Because the controlled (output) power can be higher than the controlling (input) power, a transistor can amplify a signal.



CHAPTER: 5COST OF PROJECT

COST OF PROJECT:

SR.NO COMPANENTS NAME QUNTIT COST/NO. TOTAL



Y RS/- COST RS/-

1 PIC16F877A MICROCONTROLLER 1 85 85

2 1 MICRO F CAPASITOR 8 1 8

3 10 MICRO F CAPASITOR 1 15 15

4 22 PF CAPASITOR 8 3 24

5 10 KΩ RESISTOR 17 3 51



8 330 Ω RESISTOR 27 1 27

9 10 KΩ PRESET 1 1 1

10 1 N 4007 DIODE 2 5 10

11 ZENER DIODE 1 5 5

12 RELAY 3 100 300

13 4MHz CRYSTAL OSCILLATOR 1 15 15

14 BC 548 NPN TRANSISTOR 5 5 25

15 LCD DISPLAY 1 120 120

16 40 PIN IC SOCKET 1 40 40

17 CURRENT TRANSFORMER 1 150 150

18 POTENTIAL TRANSFORMER 1 150 150

19 PCB 30CM*30CM 1 240 240

TOTAL COST 1355



Table 5.1 cost of project



CHAPTER: 6

ADVANTAGES, DISADVANTGES& APPLICATIONS

6.1 Advantages:

Easy operation Lower maintenance cost Low power consumption High reliability Low initial cost



6.2 Disadvantages:

Skilled person required for programming

6.3 Application:

Used in industries Domestic sector Power generation, transmission and distribution Commercial unit



CHAPTER:7REFERENCE

7.1 REFERENCES:

[1] en.wikipedia.org/wiki/Power_factor_correction

[2] Electronics for you magazine

[3] http://www.freescale.com


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