ARDUINO POWER MEASUREMENT

A thesis submitted in partial fulfilment of the requirement for the Degree of

Bachelor of technology

In

ELECTRICAL & ELECTRONICS ENGINEERING

By

T.PADMA PRIYANKA 09241A0222

T.PRASANTHI 09241A0226

D.SUJANA 09241A0249

ZEBA TANVEER 09241A0251

Under the guidance of

Ms. P.SRIVIDYADEVI

2012-2013 DEPARTMENT OF ELECTRICAL & ELECTRONICS ENGINEERING

GOKARAJU RANGARAJU INSTITUTE OF ENGINEERING &

TECHNOLOGY

BACHUPALLY, HYDERABAD 500090

2012-2013

GOKARAJU RANGARAJU INSTITUTE OF ENGINEERING &

TECHNOLOGY

Hyderabad, Andhra Pradesh.

DEPARTMENT OF ELECTRICAL & ELECTRONICS ENGINEERING

C E R T I F I C A T E

This is to certify that the project report entitled ARDUINO POWER

MEASUREMENT that is being submitted by Ms. T.PadmaPriyanka, Ms.

T.Prasanthi, Ms. D.Sujana, Ms. ZebaTanveer in partial fulfilment for the

award of the Degree of Bachelor of Technology in Electrical and Electronics

Engineering to the Jawaharlal Nehru Technological University as a record of

bonafide work carried out by them under my supervision. The results embodied

in this project report have not been submitted to any other University or

Institute for the award of any graduation degree.

H.O.D Internal Guide

(P.M.SARMA) (P.SRIVIDYADEVI)

Professor Assistant Professor

External Examiner

ACKNOWLEDGEMENT

This is to place on record our appreciation and deep gratitude to the persons without whose

support this project would never see the light of day.

We wish to express our propound sense of gratitude to Mr. P. S. Raju, Director, G.R.I.E.T for his

guidance, encouragement, and for all facilities to complete this project.

We also express our sincere thanks to Mr. P. M. Sarma, Head of the Department, Electrical and

Electronics Engineering, G.R.I.E.T for extending his help.

We have immense pleasure in expressing our thanks and deep sense of gratitude to our guide

Ms. P. SriVidyaDevi, Assistant Professor, Department of Electrical and Electronics Engineering,

G.R.I.E.T for her guidance throughout this project.

We express our gratitude to Mr. E. Venkateshwarlu, Associate Professor, Department of

Electrical and Electronics Engineering, Coordinator, G.R.I.E.T for his valuable recommendations

and for accepting this project report.

Finally we express our sincere gratitude to all the members of faculty and our friends who

contributed their valuable advice and helped to complete the project successfully.

T.PADMA PRIYANKA (09241A0222) T.PRASANTHI (09241A0226)

D.SUJANA (09241A0249)

ZEBA TANVEER (09241A0251)

ABSTRACT

The main objective of this study Arduino Power Measurement aims to measure power

consumption with higher resolution. The goal of providing such data to a user is that they will

optimise and reduce their power usage as poor power quality causes trouble in receptable

equipment malfunctions. The demand for power has increased exponentially over the last

century. One avenue through which todays energy problems can be addressed is through the

reduction of energy usage in households. This has increased the emphasis on the need for

accurate and economic methods of power measurement. The goal of providing such data is to

optimize and reduce their power consumption.

In this project various power measurement methods are described briefly and the cutting

edge of Arduino power measurement is then discussed along with a detailed description of

Arduino Power measurement. Some of the theory, hardware and software associated with this

project are given. The importance, role of Arduino is discussed. The current and voltage signals

from the load are stepped down and offseted before they are given to the Arduino. Load circuit,

Offset circuit and their construction and functionality in the project are discussed.

Power is rate of expending energy. For DC circuits and purely resistive AC circuits,

power is product of voltage and current. For reactive AC circuits the product of r.m.s values of

voltage and current is termed as apparent power (VA).

Arduino is an open-source single board microcontroller, descendant of the open-

source wiring platform designed to make the process of using electronics in multidisciplinary

projects

Arduino Sketch is programmed accordingly to give the average power consumed by the

load. Using Processing and Megunolink softwares the output power is displayed graphically for

better readability.

i

CONTENTS

Abstract

Contents.i

List of figures.....iv

CHAPTER 1: INTRODUCTION

1.1 Introduction..1

1.2 Project overview...2

1.3 Organisation of thesis.......2

CHAPTER 2: POWER AND ARDUINO POWER

MEASUREMENT

2.1 Power..4

2.1.1 DC circuits....4

2.1.2 AC circuits....5

2.2 Components of power.5

2.2.1 Average power...5

2.2.2 Instantaneous power.......5

2.3 Power factor.6

2.4 Power measurement....6

2.4.1 Using various measuring equipments.................6

2.4.2 Power measurement using software........9

ii

CHAPTER 3: SYSTEM DESIGN

3.1 Software....12

3.1.1 Arduino12

3.1.1.1 Arduino Hardware........13

3.1.1.2 Arduino Software......14

3.1.1.3 Features.....15

3.1.1.4 Pin description......16

3.1.1.5 Arduino sketch...16

3.1.2 Processing Sketch.18

3.1.2.1 Void setup..18

3.1.2.2 Void draw..19

3.1.2.3 Void serialEvent.19

3.1.3 MegunoLink software.......20

3.2 Hardware....21

3.2.1 Block diagram of Arduino Power Measurement..........21

3.2.1.1 Description.....21

3.2.2 Offset data conditioning card...22

3.2.2.1 Function........22

3.2.2.2 Description....23

3.2.3 Regulated DC supply.......24

3.2.4 Load circuit......25

iii

CHAPTER 4: SIMULATION RESULT

4.1 Single load.................27

4.2 Two loads......29

4.3 Three loads..31

4.4 Varying loads...............33

CHAPTER 5: CONCLUSION

5.1 Conclusion..............34

5.2 Scope for work........34

References

Appendix-A

Appendix-B

iv

LIST OF FIGURES

Fig. No Name of the Figure Page. No.

2.4(a) DC power measurement using ammeter and voltmeter 7

2.4(b) Electrodynamometer wattmeter 8

2.4(c) Digital wattmeter 8

2.4(d) Power triangle 9

2.4(e) Simulation circuit of 2-wattmeter method power measurement 10

3.1.1(a) Arduino 15

3.1.1(b) Arduino sketch 17

3.1.2 Processing sketch 20

3.1.3 Megunolink plot 21

3.2.1(a) Block Diagram of Arduino Power Measurement 22

3.2.2(a) Simulation circuit of data conditioning card in multisim 22

3.2.2(b) Simulation results of offset cards in multisim 23

3.2.2(c) Offset card hardware 23

3.2.3(a) Regulated DC supply circuit 24

3.2.3(b) Simulation result of regulated DC supply in multisim 25

3.2.3(c) Regulated DC supply hardware 25

3.2.4(a) Load circuit 26

3.2.4(b) Load circuit hardware 26

4.1(a) Serial monitor values for single load in Arduino 27

4.1(b) Megunolink plotting for single load 28

4.1(c) Graph for single load in Processing sketch 28

v

4.2(a) Serial monitor values for two loads in Arduino 29

4.2(b) Megunolink plotting for two loads 30

4.2(c) Graph for two loads in Processing sketch 30

4.3(a) Serial monitor values for three loads in Arduino 31

4.3(b) Megunolink plotting for three loads 32

4.3(c) Graph for three loads in Processing sketch 32

4.4(a) Megunolink plotting for varying loads 33

4.4(b) Graph for varying loads in Processing sketch 33

1

CHAPTER 1

Introduction

1.1 Introduction

Power is rate at which electric energy is transferred by an electric circuit. Power is a

important electrical quantity and everything in our world today depends on having the power to

keep them running. It is necessary to measure the amount of electric power a power plant

generates and a customer uses over a period of time. It helps in estimation of transmission losses

between the generation- distribution and distribution-consumer apparatus. This estimation helps

in power theft detection and to reduce the transmission losses. Measurement of electrical power

may be done to measure electrical parameters of a system.

In the existing power utility set up, consumers are presented with usage information only

once a month with their bill. The length of time between updates about power usage is far too

long for a consumer to observe a changed behaviours effect on power usage. In addition utility

bills can be convoluted in how they present usage information, and a consumer may not be able

to decipher changes in their power usage from the last bill. An opportunity to educate customers

on power usage is lost because of these realities.

If a person can know how much power is consumed, they may be more careful in the

future about letting devices run when not needed. The goal of creating more awareness about

energy consumption would be optimization and reduction in energy usage by the user. This

would reduce their energy costs, as well as conserve energy.

The project Arduino Power Measurement, aims to determine power consumption and to

display it graphically. The goal of providing such data to a user is that they will optimize and

reduce their power usage. The arduino based power measurement aims to measure power

consumption with higher resolution and consumes lesser power.

2

1.2 Overview:

In the project Arduino Power Measurement, power consumed by the load is measure by

using programming Arduino sketch. The load circuit comprises of resistive loads. The current

flowing through the load circuit and the voltage across the load circuit are stepped down by using

instrument transformers. These voltage and current signals are negative offsetted using data

conditioning card and are then given to Arduino board. Power measurement is done by

programming Arduino sketch.

Power is rate of doing work. For DC circuits and purely resistive AC circuits, power is

product of voltage and current. For reactive AC circuits the product of r.m.s values of voltage

and current is termed as apparent power (VA).

Arduino is an open-source single board microcontroller, descendant of the open-

source wiring platform designed to make the process of using electronics in multidisciplinary

projects. It is an electronics prototyping platform based on flexible and easy to use hardware cum

software. Arduino uno, a microcontroller board based on the ATmega328 is used in this project.

The power digitally measured using Arduino is displayed graphically by using Processing

and MegunoLink softwares.

1.3 Organisation of thesis

Chapter 1 presents introduction part and also a brief overview of the project.

Chapter 2 presents the basic fundamentals of power, components of power, power factor,

power measurement and also different types of power measurement.

Chapter 3 deals with the hardware and software part of the project Arduino Power

measurement. This hardware part consists of offset cards, regulated dc supply, load circuit and

arduino hardware. The software part consists of programming parts of Arduino, Processing and

Megunolink softwares

3

. Chapter 4 shows the simulation results of three loads using Arduino, Processing and

Megunolink softwares and also simulation results for varying loads are shown using Processing

and Megunolink softwares.

Chapter 5 address the conclusion of the project and scope for work, which describes the

different methods to extend the project in future.

4

CHAPTER 2

Power and Power Measurement

2.1 Power

Power is rate of expending energy. The unit of power is Watt (joule per second (J/s)). For

DC circuits and purely resistive AC circuits, power is product of voltage and current. For

reactive AC circuits the product of r.m.s values of voltage and current is termed as apparent

power (VA).

The potential difference in volts between two points is equal to the energy per unit charge

(in joules/coulomb) which is required to move electric charge between the points. Since the

electric current measures the charge per unit time (in coulombs/second), the electric power p is

given by the product of the current I and the voltage V (in joules/second = watts).

Where,

Q is electric charge in coulombs

t is time in seconds

I is electric current in amperes

V is electric potential or voltage in volts

2.1.1 DC Circuits

In the case of resistive (Ohmic, or linear) loads, Joule's law can be combined with Ohm's

law (V = IR) to produce alternative expressions for the dissipated power:

where R is the electrical resistance.

5

2.1.2 AC Circuits

In alternating current circuits, energy storage elements such as inductance and capacitance may

result in periodic reversals of the direction of energy flow.

Active Power: The portion of power flow that, averaged over a complete cycle of the AC

waveform, results in net transfer of energy in one direction is known as real power (active

power). It is the power consumed by the resistive elements in the circuit. Active power is the

power that is actually being consumed by the load.

Reactive power: The portion of power flow due to storage elements that returns to the source in

each cycle is known as reactive power.

When the voltage and current are periodic with the same fundamental frequency, the

instantaneous power is also periodic with twice the fundamental frequency.

2.2 Components of power

2.2.1 Average Power:

Average power is defined as the energy transfer rate averaged over many periods of the lowest

frequency in the signal. It is also defined as the average amount of work done or energy

converted per unit of time. If W is the amount of work performed during a period of time t,

the average power Pavg over that period is given by the formula

Pavg = W/t

2.2.2 Instantaneous Power:

The instantaneous power is then the limiting value of the average power as the time

interval t approaches zero.

P= Limt0 Pavg

Electric power is usually produced by electric generators, but can also be supplied by

chemical sources such as electric batteries. Electric power is generally supplied to businesses and

homes by the electric power industry.

6

2.3 Power factor:

The ratio between real power and apparent power in a circuit is called the power factor.

It's a practical measure of the efficiency of a power distribution system. For two systems

transmitting the same amount of real power, the system with the lower power factor will have

higher circulating currents due to energy that returns to the source from energy storage in the

load. These higher currents produce higher losses and reduce overall transmission efficiency. A

lower power factor circuit will have a higher apparent power and higher losses for the same

amount of real power.

The power factor is unity (one) when the voltage and current are in phase. It is zero when

the current leads or lags the voltage by 90 degrees. Power factors are usually stated as "leading"

or "lagging" to show the sign of the phase angle of current with respect to voltage.

Purely capacitive circuits supply reactive power with the current waveform leading the

voltage waveform by 90 degrees, while purely inductive circuits absorb reactive power with the

current waveform lagging the voltage waveform by 90 degrees. The result of this is that

capacitive and inductive circuit elements tend to cancel each other out.

When the waveforms are purely sinusoidal, the power factor is the cosine of the phase

angle () between the current and voltage sinusoid waveforms. Equipment data sheets and

nameplates often will abbreviate power factor as "cos".

2.4 Power measurement:

Power measurement is done for both AC circuits and DC circuits. Power can be

measured by using different methods namely:

Using various measuring equipments.

By interfacing the circuit with any software

2.4.1 Using various measuring equipments

Equipments which measure current, voltage, power are used. These methods are as

follows:

7

a) Using Voltmeter and Ammeter: DC power can be measured by measuring Voltage and

Current. Two circuits are shown for DC power measurement.

Figure 2.4(a): DC power measurement using Ammeter and Voltmeter

The disadvantage of the above power measurement is:

In the first circuit, Ammeter measures current which flow into the voltmeter and

load.

In the second circuit, Voltmeter measures voltage drop across the ammeter in

addition to that dropping across the load.

So the above method is not accurate.

b) Using Wattmeter:

1. Dynamometer

2. Digital wattmeter

Dynamometer: A dynamometer can measure power in both DC and AC systems. A

dynamometer has two coils: static coil and movable coil. It uses the interaction between

the magnetic fields produced by the currents in two coils or sets of coils to measure

power. Torque is proportional product of current in current coil and current in voltage

coil. The Accuracy of dynamometer is nearly 0.25 %.

8

Figure 2.4(b): Electrodynamometer Wattmeter

Digital wattmeter (up to 100 kHz): A modern digital electronic wattmeter/energy meter

samples the voltage and current thousands of times a second. For each sample, the

voltage is multiplied by the current at the same instant; the average over at least one cycle

is the real power. A computer circuit uses the sampled values to calculate RMS voltage,

RMS current, VA, power (watts), power factor, and kilowatt-hours. The readings may be

displayed on the device, retained to provide a log and calculate averages, or transmitted

to other equipment for further use.

Advantages of digital wattmeter:

High-resolution

Accuracy

Figure 2.4(c): Digital Wattmeter

9

c) Power Triangle Method:

Real and reactive powers can also be calculated directly from the apparent power, when

the current and voltage are both sinusoids with a known phase angle between them:

Figure 2.4(d): Power Triangle

(Apparent power)2

= (real power)2+ (Reactive power)

2

Real power = (apparent power)*(cos)

Reactive power = (apparent power)*(sin)

2.4.2 Power measurement using software:

a) Power measurement using Multisim: In Multisim power can be measured using various

methods like 1-wattmeter method, 2-wattmeter method, 3-wattmeter method. One such method

is discussed in detail here.

Two wattmeter method: In this method power is measured for three phase balanced loads using

two wattmeters. The total power consumed is calculated using the below formula.

Total Power Consumed, Wtotal= 3*(W1+ W2)

Where, W1 first wattmeter reading

10

W2 second wattmeter reading

Let us consider a three phase circuit having resistive balanced loads. Connect the circuit in

multisim and the total power calculated is 900watts using the above formula.

Figure 2.4(e): Simulation circuit of 2-wattmeter method power measurement in multisim

b) Power measurement using Labview:

Power measurement can also be done using Labview software. Labview is a system

design platform and development environment for a visual programming language. Labview ties

the creation of user interfaces (called front panels) into the development cycle. Labview

programs/subroutines are called virtual instruments (VIs). The graphical approach also allows

non-programmers to build programs by dragging and dropping virtual representations of lab

equipment with which they are already familiar.

c) For a three-phase system, a single-phase wattmeter can be connected in each phase.

Using this three-wattmeter configuration, the total real power can be obtained by adding the

three wattmeter readings.

11

Total power consumed, P = P1 + P2+ P3

Where, P1- wattmeter reading first phase

P2- wattmeter reading second phase

P3- wattmeter reading third phase

The above methods implemented either in software or in hardware. Whereas in Arduino Power

Measurement project, the load circuit is interfaced with Arduino board, and is then programmed

for power measurement. This project can also be extended for power measurement in a three

phase system. So this project is advantageous compared to other methods.

12

CHAPTER 3 System Design

3.1 Software

3.1.1 Arduino

Arduino is an open-source electronics prototyping platform based on flexible, easy-to-use

hardware and software. It is a single board microcontroller, descendant of the open-source wiring

platform designed to make the process of using electronics in multidisciplinary projects. Arduino

Uno, a microcontroller board based on the ATmega328 is used in this project. The hardware

consists of a simple open hardware design for the Arduino board with an on-

board input/output support. The software consists of a standard programming language compiler

and the boot loader that runs on the board. Arduino hardware is programmed using a Wiring-

based language (syntax and libraries), similar to C++ with some slight simplifications and

modifications, and a Processing-based integrated development environment.

Arduino can sense the environment by receiving input from a variety of sensors and can

affect its surroundings by controlling lights, motors, and other actuators. The microcontroller on

the board is programmed using the Arduino programming language (based on Wiring) and the

Arduino development environment (based on Processing). Arduino projects can be stand-alone

or they can communicate with software running on a computer (e.g. Flash, Processing, MaxMSP

and Megunolink). The hardware reference designs (CAD files) are available under an open-

source license; you are free to adapt them to your needs. The open-source Arduino environment

makes it easy to write code and upload it to the i/o board. It runs on Windows, Mac OS X, and

Linux. In addition to all the features of the previous board, the Uno now uses an ATmega8U2

instead of the FTDI chip. This allows for faster transfer rates, no drivers needed for Linux or

Mac (in file for Windows is needed), and the ability to have the Uno show up as a keyboard,

mouse, joystick, etc.

13

3.1.1.1 Arduino Hardware:

An Arduino board consists of an 8-bit Atmel AVR microcontroller with complementary

components to facilitate programming and incorporation into other circuits. An important aspect

of the Arduino is the standard way that connectors are exposed, allowing the CPU board to be

connected to a variety of interchangeable add-on modules known as shields. Some shields

communicate with the Arduino board directly over various pins, but many shields are

individually addressable via an IC serial bus, allowing many shields to be stacked and used in

parallel. Official Arduinos have used the megaAVR series of chips, specifically the ATmega8,

ATmega168, ATmega328, ATmega1280, and ATmega2560. A handful of other processors have

been used by Arduino compatibles. Most boards include a 5 volt linear regulator and a

16 MHz crystal oscillator (or ceramic resonator in some variants), although some designs such as

the LilyPad run at 8 MHz and dispense with the onboard voltage regulator due to specific form-

factor restrictions. An Arduino's microcontroller is also pre-programmed with a boot loader that

simplifies uploading of programs to the on-chip flash memory, compared with other devices that

typically need an external programmer.

At a conceptual level, when using the Arduino software stack, all boards are programmed

over an RS-232 serial connection, but the way this is implemented varies by hardware version.

Serial Arduino boards contain a simple inverter circuit to convert between RS-232-level

and TTL-level signals. Current Arduino boards are programmed via USB, implemented using

USB-to-serial adapter chips such as the FTDI FT232. Some variants, such as the Arduino Mini

and the unofficial Board uno, use a detachable USB-to-serial adapter board or

cable, Bluetooth or other methods. (When used with traditional microcontroller tools instead of

the Arduino IDE, standard AVR ISP programming is used.)

The Arduino board exposes most of the microcontroller's I/O pins for use by other circuits. The

Diecimila, Duemilanove, and current Uno provide 14 digital I/O pins, six of which can

produce pulse-width modulated signals, and six analog inputs. These pins are on the top of the

board, via female 0.1 inch headers. Several plug-in application shields are also commercially

available.

14

3.1.1.2 Arduino Software:

The Arduino IDE is a cross-platform application written in Java, and is derived from the

IDE for the Processing programming language and the Wiring project. It is designed to introduce

programming to artists and other newcomers unfamiliar with software development. It includes a

code editor with features such as syntax highlighting, brace matching, and automatic indentation,

and is also capable of compiling and uploading programs to the board with a single click. There

is typically no need to edit make files or run programs on a command-line interface. Although

building on command-line is possible if required with some third-party tools such as Ino.

The Arduino IDE comes with a C/C++ library called "Wiring" (from the project of the same

name), which makes many common input/output operations much easier. Arduino programs are

written in C/C++, although users only need define two functions to make a runnable program:

setup() a function run once at the start of a program that can initialize settings

loop() a function called repeatedly until the board powers off

It is a feature of most Arduino boards that they have an LED and load resistor connected

between pin 13 and ground, a convenient feature for many simple tests.[29]

The above code

would not be seen by a standard C++ compiler as a valid program, so when the user clicks the

"Upload to I/O board" button in the IDE, a copy of the code is written to a temporary file with an

extra include header at the top and a very simple main() functionat the bottom, to make it a valid

C++ program. The Arduino IDE uses the GNU tool chain and AVR Libc to compile programs,

and uses avr to upload programs to the board.

As the Arduino platform uses Atmel microcontrollers Atmels development environment,

AVR Studio or the newer Atmel Studio, may also be used to develop software for the Arduino.

The Arduino hardware reference designs are distributed under a Creative Commons Attribution

Share-Alike 2.5 license and are available on the Arduino Web site. Layout and production files

for some versions of the Arduino hardware are also available. The source code for the IDE and

the on-board library are available and released under the GPLv2 license.

Arduino and Arduino-compatible boards uses of shields, which are printed circuit boards

that sit atop an Arduino, and plug into the normally supplied pin-headers. These are expansions

15

to the base Arduino. There are many functions of shields, from motor controls, to breadboarding

(prototyping).

3.1.1.3 Features

ATmega328 microcontroller

Input voltage - 7-12V

14 Digital I/O Pins (6 PWM outputs)

6 Analog Inputs

32k Flash Memory

16Mhz Clock Speed

The maximum values that Arduino can handle:

Max frequency: 16MHz

Max Voltage: 5V

Max Current: 50mA

Fig: 3.1.1(a) Arduino

16

3.1.1.4 Pin description

Arduino can be powered using power jack, USB port. Apart from this it can also be

powered by using a external battery or AC to DC adaptor through pin Vin.

5V, 3.3V: there is a inbuilt regulator on the board. Through this regulator a constant DC

supply of 5V, 3.3V is provided.

Reset: This pin enables to reset the micro controller.

IOREF: This pin acts as reference to the inputs given to the arduino board.

There are 6 pins A0 A5 through which analog input can be given to the arduino board.

There are 14 digital pins 0-13. Among these (3,5,6,9,10,11) are PWM pins(pulse width

modulation) from which analog output can be taken from the arduino board.

There is a inbuilt LED on pin 13.

AREF- This pin acts as reference to the analog inputs.

Rx,Tx are used for receiving and transmitting serial data.

ICSP- (In circuit serial programming)- These pins enable the user to programme the chips

on the circuit.

3.1.1.5 Arduino sketch

Basically Arduino sketch consists of two main functions namely

1. Void setup()

2. Void loop()

Void setup():

Setup () is called when a sketch starts. It is used to initialize variables, pin modes, start using

libraries etc. The setup () will only run once, after each power up or reset of the Arduino board.

17

Syntax:

Void setup ()

{

Statements;

}

Void loop():

After creating a setup () function which initializes and sets the initial values, the loop ()

function does precisely what its name suggests, and loops consecutively, allowing your program

to change and respond. It is used to actively control the Arduino board.

Syntax:

Void loop ()

{

Statements;

}

Figure 3.1.1(b): Arduino sketch

18

3.1.2 Processing sketch

Processing is an open source programming language and environment for creating

graphs, images, animations, and interactions. Initially developed to serve as a software

sketchbook and to teach fundamentals of computer programming within a visual context,

Processing also has evolved into a tool for generating finished professional work. Today, there

are tens of thousands of students, artists, designers, researchers, and hobbyists who use

Processing for learning, prototyping, and production.

Basically Programming using Processing software uses three main functions namely

Void setup()

Void draw()

Void serialEvent()

3.1.2.1 Void setup()

The setup () function is called once when the program starts. It is used to define initial

environment properties such as screen size and background color and to load media such as

images and fonts as the program starts. There can only be one setup () function for each program

and it shouldn't be called again after its initial execution. Note: Variables declared within setup

() are not accessible within other functions, including draw ().

Syntax:

Void setup ()

{

Statements;

}

19

3.1.2.2 Void draw()

It is called directly after setup (), the draw () function continuously executes the lines of

code contained inside its block until the program is stopped or no Loop () is called. draw () is

called automatically and should never be called explicitly.

It should always be controlled with no Loop (), redraw () and loop (). After no

Loop () stops the code in draw () from executing, redraw () causes the code inside draw () to

execute once, and loop () will cause the code inside draw () to resume executing continuously.

The number of times draw () executes in each second may be controlled with the

frameRate () function. There can only be one draw () function for each sketch, and draw

() must exist if you want the code to run continuously, or to process events such as mouse

Pressed (). Sometimes, you might have an empty call to draw () in your program.

Syntax:

Void draw ()

{

Statements;

}

3.1.2.3 Void serialEvent():

It is called when data is available. Use one of the read() methods to capture this data. The

serialEvent () can be set with buffer () to only trigger after a certain number of data elements

are read and can be set with bufferUntil() to only trigger after a specific character is read.

The which parameter contains the name of the port where new data is available, but is only

useful when there is more than one serial connection open and it's necessary to distinguish

between the two.

20

Syntax:

Void serialEvent(which port)

{

Statements;

}

Figure3.1.2: Processing Sketch

3.1.3 MegunoLink software

MegunoLink is a free program to upload compiled binary files to the Arduino micro controller

and monitor communications from the device. It allows you to go away from the simple Arduino

development environment and use a more full featured environment.

21

Figure 3.1.3: Megunolink Plot

3.2 Hardware

3.2.1 Block diagram of Arduino Power Measurement

3.2.1.1 Description

The block diagram of the project Power Measurement using Arduino is as shown. The

load circuit consists of resistive loads which are bulbs each of rating 200watts. These loads are

energized by single phase 230v DC AC supply. The current and voltage through the load are

stepped down to safer values by using a current transformer and potential transformer

respectively. As the AC signals cant be given to Arduino board, these signals are offsetted using

voltage and current offset data conditioning cards. These cards are energized using regulated DC

supply. The function of offset data conditioning cards is to clamp the AC signal with respect to a

preset reference DC voltage. The output waves from the voltage offset card are given as analog

input to Arduino board at pins A0 and ground. Similarly the output from the current offset card is

given as analog input to Arduino board at the pins A2 and ground. Once the analog inputs are

given to Arduino, the microcontroller on the board is programmed for the measurement of power

in Arduino sketch.

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Figure 3.2.1(a): Block diagram of Arduino Power Measurement

3.2.2 Offset data conditioning card

3.2.2.1 Function

The function of offset data conditioning card is to clamp the given AC signal with respect

to a reference DC voltage. The reference DC voltage is preset according to the components used

in the circuit which intern depends on the maximum load rating.

Figure 3.2.2(a): Simulation circuit of offset data conditioning card in multisim

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3.2.2.2 Description

The circuit diagram of the offset data conditioning card is as shown. It consists of two op-

amps, UA714CN which are operated in inverting mode. The first op-amp is used as a summing

amplifier. It adds up the input signal with the DC reference voltage. The output of the first op-

amp is inverted using the second op-amp which acts as an inverting amplifier. The output of this

op-amp is taken out as the output of the offset data conditioning card.

Figure 3.2.2(b): Simulation results of offset card in multisim

Figure 3.2.2(c): Offset card hardware

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3.2.3 Regulated DC supply

Regulated DC supply of +12, 0, -12v is used to energize the offset data conditioning card.

The circuit diagram of the regulated Dc supply card is as shown in figure. Here firstly the single

phase 230v AC supply is stepped down to 15v AC by using a step down transformer.

Figure 3.2.3(a): Regulated DC supply circuit

From this AC voltage all the harmonics are removed by using diodes and the output

voltage is further converted to constant DC voltage by using regulators 7812 and 7912. From this

voltage the distortions are removed by using capacitive filters. This circuit finally outputs a

voltage of +12, 0, -12v.

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Figure 3.2.3(b): Simulation circiut of regulated DC supply in multisim

Figure 3.2.3(c): Regulated DC supply hardware

3.2.4 Load circuit

The load circuit consists of resistive loads which are bulbs as shown in the figure. These

loads are each of wattage 200watts. The maximum load being used is 600watts.The current and

voltage values of load are stepped down by using current transformer and potential transformer

respectively.

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Figure 3.2.4(a): Load circuit

Figure 3.2.4(b): Load circuit hardware

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CHAPTER 4

Simulation results

4.1 Single Load

When the first load having a rating of 200watts is switched on, the Arduino Serial monitor

displays the average power consumed as 170watts in its COM window as shown in figure 4.1(a).

Graphically it can be obtained using Megunolink software and Processing software. The figure

4.1(b) represents a graph between average power in watts and time in seconds using Megunolink

software. Figure 4.1(c) represents the graph which is displayed using Processing software.

Figure 4.1(a): Serial monitor values for single load in Arduino

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Figure 4.1(b): Megunolink plotting for single load

Figure 4.1(c): Graph for single load in Processing sketch

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4.2 Two Loads

When two bulbs each of rating 200watts is switched on, the average power values in the serial

monitor shows nearly 410watts as shown in the figure 4.2(a). Due to transformer losses, the

value in the serial monitor is displayed as 410watts instead of 400watts. The figure 4.2(b)

represents a graph between average power in watts and time in seconds using Megunolink

software. From this graph we can observe the change in average power consumed when the

second load is switched on. Figure 4.2(c) represents the graph which is displayed using

Processing software.

Figure 4.2(a): Serial monitor values for two loads in Arduino

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Figure 4.2(b): Megunolink plotting for two loads

Figure 4.2(c): Graph for two loads in Processing sketch

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4.3 Three Loads

When three loads are switched on(having a total rating of 600watts), the average power values in

the serial monitor shows nearly 660watts as shown in the figure 4.3(a). Due to transformer

losses, the value in the serial monitor is displayed as 660watts instead of 600watts.The figure

4.3(b) represents a graph between average power in watts and time in seconds using Megunolink

software. From this graph we can observe the change in average power consumed when the third

load is switched on. Figure 4.3(c) represents the graph which is displayed using Processing

software.

Figure 4.3(a): Serial monitor values for three loads in Arduino

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Figure 4.3(b): Megunolink plotting for three loads

Figure 4.3(c): Graph for three loads in Processing sketch

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4.4 Varying Loads

If the loads are increased and decreased in a step wise manner then the graphs obtained in

Megunolink and Processing softwares will be as follows respectively.

Figure 4.4(a): Megunolink Plotting for varying loads

Figure 4.4(b): Graph for varying loads in Processing sketch

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CHAPTER 5 Conclusion

5.1 Conclusion

Power measurement is done for resistive loads up to a maximum load of 600watts using Arduino

environment. Results for three loads are shown in simulation. Arduino Power Measurement is an

advanced method of determining power and this method is more advantageous than other

softwares such as Labview. The advantages of Arduino over other softwares are it simplifies

the amount of hardware and software development needed inorder to get a system running. It is

open source software and can be extended by experienced programmers. Arduino has simple and

clear programming environment and also has a quicker writing code. From the above discussion

Arduino Power Measurement is an advanced method of measuring power and can also observe it

graphically.

5.2 Scope for work

Proper performance, reliability, stability of power being consumed and generated must be

ensured. Therefore it is necessary to measure, test and analyze the power consumption to every

aspect of power system for its performance and behaviour, under normal as well as extreme

operating conditions.

The present project can be further extended for measuring the energy consumption in KWHs.

This KWH reading can be provided to the user for their easy understanding. The same can be

displayed graphically to observe the excess consumption of energy and can be minimized

accordingly.

Apart from this Arduino based wireless power meter can also be implemented. The Arduino

based wireless power meter is a non-invasive current meter for household power with an

Arduino interface. Current through the load is measured using split core current transformers.

This data is then transmitted through the homes wireless router and back to the base station and

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is represented visually to the user. This method provides the domestic power consumption

accurately, safely, and with a relatively fast update rate, thus helping the user optimize and

reduce their power usage.

REFERENCES

[1] www.arduino.cc

[2] www.processing.org

[3] www.blueleafsoftware.com/Resources/EmbeddedSand/MegunoLink

[4] Electrical and electronic instruments and measurements by A.K.Sawhney

[5] eBook. Download/ Experiment_3_Power_Measurements.pdf

[6] eBook. Download /wer_measurements_and_analysischallenges_and_soluti_94554.pdf

[7] eBook. Download /Measurement_of_electrical_power.pdf

[8] eBook. Download/ Power.pdf

[9] eBook. people.ece.cornell.edu/land/courses/.../DESIGN_REPORT.pdf/

APPENDIX-A

Arduino program for measuring power and displaying graphically using MegunoLink

#include // Including the header file

GraphSeries g_aGraphs[] = {"power(Watts)"}; // Plotting graph for power in Watts

float Voltage = A0; //Defining and initializing the voltage

float Current = A2; // Defining and initializing the current

float I = 0;

float V = 0;

float P = 0;

float P1 = 0;

void setup()

{

Serial.begin(9600);

pinMode(Voltage,INPUT); //Set voltage as input pin

pinMode(Current,INPUT); //Set current as input pin

pinMode(P1,OUTPUT); //Set power as output pin

}

void loop()

{

float realPower = 0;

for(int i=0;i

I= ((analogRead(Current)-(2.22*204.6))/(204.6*20))*(76.667*1.414);

//Current from A2 is negative offsetted to get AC voltage waveform, which is then converted to

current by dividing voltage with appropriate resistance to get AC current waveform and is then

multiplied with transformation ratio of CT to get actual current waveform

P=V*I; // Voltage and current waves are multiplied at some instants

realPower=realPower+abs(P); //Power is added after successive instants

delay(0.05);

}

P1=realPower/400.0; // Above obtained power is averaged by number of instants

Serial.println(P1); //Moving the value of average power to com window

g_aGraphs[0].SendData(P1); // Displayed average power using MegunoLink

}

APPENDIX-B

Program to display the average power in Processing software

import processing.serial.*; //Importing data from Arduino to processing software

Serial port;

int xPos=1; //Defining a variable for position of x

int dely=10; // Defining a variable for position of y

void setup()

{

size(1280,768); // Declaring the size of display screen

port = new Serial(this, "COM5", 9600); // Set the com port same as that of Arduino

port.bufferUntil('\n'); // Repeat the data until new line character is encountered

}

void draw() // used for 3D geometry

{

}

void serialEvent (Serial port)

{

String inString = port.readStringUntil('\n');

// Reading the data from strings until new line character is encountered

if (inString != null) // Checking if string is empty

{

inString = trim(inString);

// This function removes the spaces from the beginning and end of string including tab spaces

float inByte = float(inString); // Storing the new string as float

inByte = map(inByte, 0, 1023, 0, height);

// This function remaps the numbers in the string from one range to another

line(xPos,height,xPos,height - dely);

// Line function with 4 parameters used to display 2D line

stroke(inByte,0,255); // Used for colouring of line

noFill(); // Disables the filling of geometry

line(xPos, height- inByte, xPos, height);

if (xPos >= width // Check for the position of x and width of screen

{

xPos = 0; // If xpos is greater than width of screen reinitialize it to zero position

background(0); // Colouring of the background

}

else

{

xPos++; // If xpos is not greater than width of screen then incrementing its value

}

}

}