V O U M - $ka m m m i i FFATURES EXTRACTION USING MATLAB

I'ARiDAH HANI!*! BINT! MOHD NOH

U^iVi-RSIT! TOM HUSSEIN OWN MALAYSIA

PERPUSTAKAAN UTHM

*30000002161581* a/no 153

UNIVERSITI TUN HUSSEIN ONN MALAYSIA

BORANG PENGESAHAN STATUS TESIS4

JUDUL : VOLTAGE SAG WAVEFORM FEATURES EXTRACTION USING

MATLAB

SESI PENGAJIAN: 2007 / 2008

Saya F ARID AH HANIM BINTIMOHD NOH

( HURUF BESAR )

mengaku membenarkan tesis ( PSM / Sarjana / Doktor falsafah )* ini disimpan di Perpustakaan dengan syarat-syarat kegunaan seperti berikut:

1. Tesis ini hakmilik Kolej Universiti Teknologi Tun Hussein Onn. 2. Perpustakaan dibenarkan membuat salinan untuk tujuan pengajian sahaja 3. Perpustakaan dibenarkan membuat salinan tesis ini sebagai bahan pertukaran antara institusi

pengajian tinggi. 4. ** Sila tandakan ( V )

SULIT

TERHAD

( Mengandungi maklumat yang berdaijah keselamatan atau kepentingan Malaysia yang termaktub di dalam AKTA RAHSIA RASMI 1972 )

( Mengandungi maklumat TERHAD yang telah ditentukan oleh organisasi / badan dimana penyelidikan dijalankan

V TIDAK TERHAD

( TANDATANGAN PENULIS )

Alamat Tetap :

No 14, Jin 32/10

Taman Koperasi Polis Fasa 2,

Batu Caves, K.L.

Disahkan oleh

G|AN PENYELIA )

PROF. MADYA. DR. ZAINAL ALAM BIN HARON

Nama Penyelia

Tarikh : 24 APRIL 2008 Tarikh: 24 APRIL 2008

CAT AT AN : * Potong yang tidak berkenaan. ** Jika tesis ini SULIT atau TERHAD, sila lampirkan sural daripada pihak berkuasa/organisasi

berkenaan dengan menyatakan sekali sebab dan tempoh tesis ini perlu dikelaskan sebagai SULIT atau TERHAD.

• Tesis dimaksudkan sebagai tesis Ijazah Doktor Falsafah dan Saijana secara penyelidikan, atau disertasi bagi pengajian secara kerja kursus dan penyelidikan, atau Laporan projek Sarjana Muda ( P S M ) .

"I hereby acknowledge that I have read this report and I find that its contents meet the

requirements in terms of scope and quality for the award of Master of Electrical

Engineering with Honours."

Signature of Supervisor

Name of Supervisor

Date

Prof. Madya Dr. Zainal Alam Bin Haron

VOLTAGE SAG WAVEFORM FEATURES EXTRACTION USING MATLAB

t ARID AH HANIM BINTI MOHD NOH

A project report submitted in partial fulfillment of the Requirements for the award

of Master of Electritkl feilgitieferiHg

Faculty of Electrical and Electronic Engineering

Universiti Tun Hussein Onn Malaysia

APRIL 2008

I dcclare that this report on "Voltage Sag Waveform Features Extraction Using Matlab"

is the result of my own research except for works which have been cited in the

references. The report lias not been accepted any degree and not concurrently submitted

in candidature ofany other degree.

Signature

Name of Author : FAR1DAH HAN1M B1NT1 MOHD NOH

Date : 24 APRIL 2008

iii

To my beloved husband, Muhamad Faizal bin Yaakub and to my dearest

daughter, NurAmnah Fasiliah

iv

ACKNOWLEDGEMENT

First of allr thanks to "Allah" for the continuous blessing and for giving me the strength and chances in completing this project.

I wish to express my deepest gratitude to my project supervisor, Associate Prof. Dr. Zainal Alam Bin Haron, for his guidance, support and helpful comments in doing this project.

My family deserves special mention for their constant support during the project. Special thanks go to my dearest husband and daughter for being the driving force towards the success of my project.

To all of my friends who always helping me when is needed, thanks for everything.

My sincere appreciation also goes to everyone whom I may not have mentioned above who have helped directly or indirectly in the completion of my project.

XV

ABSTRACT

In this project a software tool to extract characteristic parameters from

a voltage sag waveform has been successfully developed and tested. The real

recorded voltage sag waveform was acquired from IEEE Working Group

PI 159.2 Power Quality Event Characterisation webpage. The development of

this software tool was done using Matlab environment. Theories and methods

on voltage sag characterization was studied and analyzed. The characteristic

parameters extraction is done on two conditions of sag, which are voltage sag

in single phase condition and voltage in for three phase condition. Two signal

processing methods have been applied in order to extract the characteristic of

voltage sag in these two conditions. The applied methods are the rms

sequence and Discrete Fourier Transform. The extracted parameters or

indices of voltage sag in this project are the sag's magnitude, duration, phase

angle jump, energy, and severity, type of sag, PN factor and the characteristic

voltage. These parameters are the indices which characterize the voltage sag

in single phase and three phase condition. The values of these parameters are

displayed in the Graphical User Interface of the software tool that has been

developed. These values has been compared with the results obtain from the

manual calculation and from the simulation results on the Matlab rms and

Discrete Fourier block set.

v i

ABSTRAK

Satu perisian khas untuk mengekstrak parameter ciri-ciri lendut voltan

daripada bentuk gelombang lendut voltan telah berjaya dibina dan diuji di

dalam projek ini. Rakaman data bentuk gelombang lendut voltan sebenar

telah diambil dari laman web Kumpulan Pencirian Gangguan Kualiti Kuasa

IEEE1159.2. Pembangunan perisian ini dibuat dalam persekitaran Matlab.

Teori-teori dan kaedah untuk pencirian lendut voltan telah dikaji dan

dianalisis. Parameter ciri-ciri lendut voltan diekstrak dalam dua keadaan,

iaitu parameter lendut voltan satu fasa dan parameter lendut voltan tiga fasa.

Dua kaedah pemprosesan signal digunakan untuk pengektrakan parameter-

parameter ini. Kaedah pemprosesan yang digunakan ialah jujukan rms dan

jelmaan Fourier diskret. Parameter atau indeks lendut voltan yang diekstrak

di dalam projek ini adalah magnitud, tempoh, anjakan sudut fasa, tenaga,

keterukan, jenis lendut voltan, faktor PN dan voltan ciri. Kesemua parameter

ini adalah indeks yang mencirikan lendut voltan satu fasa dan lendut voltan

tiga fasa. Nilai kesemua parameter ini dipaparkan pada perantara pengguna

grafik bagi perisian yang telah dibina dalam projek ini. Kesemua nilai ini

kemudiannya dibandingkan dengan nilai yang diperolehi melalui pengiraan

manual dan melalui simulasi set blok rms dan diskret Fourier Matlab.

vii

TABLE OF CONTENTS

CHAPTER TITLE PAGE

DECLARATION ii

DEDICATION iii

ACKNOWLEDGEMENT iv

ABSTRACT v

ABSTRAK vi

TABLE OF CONTENTS vii

LIST OF TABLES xi

LIST OF FIGURES xiii

LIST OF ABBREVIATIONS xvi

LIST OF SYMBOLS xvii

LIST OF APPENDICES xviii

1 INTRODUCTION 1

1.1 Proj ect Background 1

1.2 Problem Statement 4

1.3 Objectives 4

1.4 Scope of the Project 5

1.5 Significance of the Study 6

2 LITERATURE REVIEW 7

2.1 Definition of Power Quality 7

2.1.1 Power Quality Monitoring 8

2.1.2 Signal Processing and Power 10

viii

Quality

2.2 Voltage Sag - A Brief Definition 11

2.2.1 Sources of Sag I f

2.2.2 Voltage Sag in Power Quality 12

Classification

2.2.3 IEEE Standard Classification 15

for Voltage sag

2.3 Voltage Sag Detection 17

2.3.1 Triggering 17

2.3.1.1 Changes in rms or 19

Waveforms

2.3.2 Segmentation 20

2.3.2.1 Segmentation Based on 22

Time Dependent rms Sequences

2.4 Voltage Sag Characterization 24

2.4.1 Available Standards 24

2.4.1.1 IEEE Standard for 25

Voltage Sag

2.4.1.2IEC Standard for 25

Voltage Sag

2.4.1.3 Industry standards SEMI 25

2.4.2 Magnitude versus Time 27

2.4.3Phase Angle versus Time 30

2.4.4 Energy and Severity 32

2.4.4.1 Voltage Sag Energy 32

2.4.4.2 Voltage Sag Severity 33

2.4.5 Three-Phase Characteristics versus 34

Time

2.4.5.1 The Symmetrical 35

Component Classification

2.5 The Previous Research 40

3 METHODOLOGY 42

3.1 Proj ect Methodology 42

ix

3.2 Software Design and Development 43

3.2.1 Program Code Development 44

3.2.1.L Magnitude -RMS Voltage 45

Sequence

3.2.1.2 Duration-Triggering using 46

RMS Voltage Sequence

3.2.1.3 Phase Angle Jump Using 47

Discrete Fourier Transform

3.2.1.4 Energy and Severity 48

3.2.1.5 Segmentation- Time 49

dependent RMS sequence

3.2.1.6 Three Phase Unbalanced Sag 49

Classification

3.2.2 Graphical User Interface Design 50

and Development

3.3 Analysis on Validity of the Results 52

4 RESULT AND ANALYSIS 54

4.1 Result 54

4.1.1 Result on Single Phase Analysis Part 55

4.1.1.1 Magnitude and Duration 55

4.1.1.2 Phase Angle Jump of 60

Voltage Sag

4.1.1.3 Energy and Severity 63

4.1.2 Results on Three Phase Analysis Part 64

4.1.2.1 Segmentation Using Fundamental 65

or rms Sequence

4.1.2.2 Result for Type of Voltage Sag, 67

PN Factor and Characteristic Voltage

4.2 Analysis on Result 70

4.2.1 Single Phase Analysis Part 70

4.2.1.1 Magnitude 71

4.2.1.2 Phase Angle Jump 78

4.2.1.3 Energy and Severity 82

XV

4.2.2Three Phase Analysis Part 86

5 CONCLUSIONS 87

5.1 Conclusions 87

52 Further Work: 89

REFERENCES 90

Appendices A - B 94

x i

LIST OF TABLES

TABLE NO. TITLE PAGE

2.1 Different between power quality events 13

and variations

2.2 Categories and Characteristics of Power 13

System Electromagnetic Phenomena

2.3 Power quality events and variations 14

2.4 Methods in triggering 18

2.5 Complex voltages for three phase 38

unbalanced sag

2.6 The symmetrical component for three phase 39

unbalanced sags

3.1 Characteristic parameters and methods used 45

in the project

4.1 Magnitude and duration of voltage sag and 57

swell for wavel .xls

4.2 Magnitude and duration of voltage sag and swell 58

for wave4.xls

4.3 Magnitude and duration of voltage sag and swell 59

Xll

for wave5.xls

4.4 Phase angle jump of voltage sag and voltage 60

swell for wavel.xls

4.5 Phase angle jump of voltage sag and voltage 61

swell for wave4.xls

4.6 Phase angle jump of voltage sag and voltage 62

swell for wave5.xls

4.7 Energy for voltage sag or voltage swell 63

4.8 Severity of voltage sag 63

4.9 Type of voltage sag, characteristic voltage 69

and PN factor

4.10 Magnitude from the software and rms block set 73

simulation for wavel .xls

4.11 Magnitude from the software and rms block set 75

simulation for wave4.xls

4.12 Magnitude from the software and rms block 77

set simulation for wave5.xls

4.13 Phase angle jump from software and block set 79

simulation for wave4.xls

4.14 Phase angle jumps from software and block set 80

simulation for wavel .xls

4.15 Phase angle jumps from software and block set 82

simulation for wave5.xls

4.16 Manual calculation for energy and severity from 83

file wavel.xls

4.17 Comparison between the measured and calculated 83

value of sag energy and severity for wavel .xls

4.18 Manual calculation for energy and severity from 84

file wave4.xls

4.19 Comparison between the measured and calculated 84

value of sag energy and severity for wave4.xls

4.20 Manual calculation for energy and severity 85

from file wave5.xls

4.21 Comparison between the measured and calculated 85

xiii

LIST OF FIGURES

FIGURE NO. TITLE PAGE

2.1 General scheme of power quality measurements 9

2.2 Role of signal processing in extraction of 10

information from power quality data

2.3 Voltage sag phenomenon due to short 12

circuit fault

2.4 IEEE 1159 subdivision of magnitude-duration 15

plane for classification of event

2.5 Instantaneous Voltage Sag 16

2.6 Voltage dip due to single-phase faults 18

2.7 The rms sequence and the predicted 20

underlying time events

2.8 Segmentation on sequence data 21

2.9 Required Semiconductor equipment 26

voltage-sag ride through capability curve

2.10 Rms voltage sequences for one cycle window 28

2.11 Phase angle of complex voltage in stationary 31

frame and rotating frame

2.12 Balanced voltage sag 34

2.13 Unbalanced three phase voltage sag 34

2.14 Four types of three-phase unbalanced voltage 36

sag in phasor- diagram form.

xiv

2.12 Balanced voltage sag 34

2.13 Unbalanced three phase voltage sag 34

2.14 Four types of three-phase unbalanced voltage 36

sag in phasor- diagram form.

3.1 Project operational framework 42

3.2 Software development 43

3.3 General flowchart of voltage sag features 44

extraction software

3.5 Sag's and swell's duration time 47

3.4 Main window for Voltage Sag Features 51

Extraction Software

3.5 Layout of the GUIs for sub-window 52

3.6 Block diagram for rms voltage simulation 53

3.7 Block diagram for fundamental component 53

voltage simulation

4.1 Rms voltage for each phases in wavel .xls 56

4.2 Rms voltage for each phases in wave4.xls 57

4.3 Rms voltage for each phases in wave5.xls 58

4.4 The phase angle shift in rotating frame 60

for wavel .xls

4 J The phase angle shift in rotating frame 61

for wave4.xls

4.6 The phase angle shift in rotating frame 62

for wave5.xls

4.7 Measures of changes in phase A, phase B 65

and phase C

4.8 The overall measures of changes in the 66

rms voltages

4.9 The segmentation area 66

4.10 The segmentation area for lower threshold value 67

4.11 The result for three phase unbalance sag 68

4.12 The three phase rms voltage for sample 71

file wavel .xls

4.13 Rms voltage for each phase in sampled 72

X V

waveform file wavel .xls

4.14 The three phase rms voltage for sampled 73

waveform file wave4.xls

4.15 Rms voltage for each phase in sampled 74

waveform files wavel.xls

4.16 The three phase rms voltage for sampled 75

waveform file wave5.xls

4.17 Rms voltage for each phase in sampled 76

waveform files wave5.xls

4.18 Phase angle jump at phase ab, phase be 78

and phase ca for wave4.xls

4.19 Phase angle jump at phase a, phase b 79

and phase c for wavel.xls

4.20 Phase angle jump at phase ab, phase be 81

and phase ca for wave5.xls

xvi

LIST OF ABBREVIATIONS

PN - Positive Negative

TEEE - Institutes of Electrical and Electronics Engineers

GUIDE - Graphical user interface development environment

IEC - International Electrotechnical Comission

rms - Root mean square

CBEMA - Computer Business Equipment Manufacturers

Association

SEMI - Semiconductor Equipment and Materials International

THD - Total Harmonic Distortion

FFT - Fast Fourier Transform

DFT - Discrete Fourier Transform

GUI - Graphical User Interface

xvii

LIST OF SYMBOLS

V(t) - Voltage or current sample

N - Size of sliding window

U rms - rms Voltage

U fund - Fundamental voltage component

V fund - Fundamental voltage component

E dip - Energy

U nom - Nominal Voltage

f o - Power system frequency

T - Duration

V - Residual voltage of sag

S e - Severity

f s . Sampling frequency

f system - Frequency of power system

e - Exponential

cp - Phase angle

Vj - Positive sequence voltage

V2 - Negative sequence voltage

V0 - Zero sequence voltage

F - PN factor

V - Characteristic voltage

xviii

LIST OF APPENDICES

APPENDIX TITLE PAGE

A. The Layout of the Graphical User Interface 94

B. The Results of Three Phase Analysis 99

1

CHAPTER 1

INTRODUCTION

1.1 Project Background

Power quality is a term which broadly refers to maintaining near

sinusoidal waveform of power distribution bus voltage at rated voltage and

frequency [1], or in other words, providing a clean sinusoidal waveform

without any power disturbances. Power quality problems or disturbances

generally appear in the form of voltage sags, swells, harmonics, flickers and

voltage imbalance. Since a large portion of power supply systems experiences

a voltage sag whenever a fault occurs, voltage sags are much more common

than actual interruptions in the power system network, but yet they are least

avoidable power quality problem faced by utilities all over the world [2],

Voltage sag can be defined as the reduction of the rms voltage to a value

below a given threshold for duration between 0.5 cycles to 1 minute [3] [4].

Recent years, utilities have been faced with rising numbers of

complaints about voltage sags [2]. This is because more loads are sensitive to

voltage sag today rather than they were just a few years ago. Many

2

applications utilize the sensitive electronics circuitry and microprocessors.

The industries are now relying more and more on the automated equipment.

Voltage sag may reset controllers and the controlled process may take

significant time to restart again. In semiconductor device fabrication, a reset

in the process will cause a significant loss in terms of productivity, time and

material [2], For many other industrial users, a single voltage sag can cause

losses equal to that caused by a power supply interruption [3]. Ironically,

research carried out by [5] shows that the number of severe sags per year is

higher than the number of interruptions per year. Due to this fact, voltage sag

has become a major concern to industries worldwide.

Many engineering efforts [27] [28], researches [1] [23] and studies

[26] [5], have been done on voltage sags. Basically, the study on voltage sags

can be classified into the following categories:

1. Characterization and detection of voltage sag.

2. Equipment immunity.

3. Stochastic assessment.

4. Mitigation.

These four categories of studies are quite dependent on each other.

But most of the times, all these studies are needed to solve a specific voltage

sag problem [25]. The basic platform of other voltage sag studies is the

characterization of the voltage sag. This study aim at acquiring knowledge of

the voltage sags characteristics. Both fault propagation studies and measured

data are being used for this. Voltage sag is normally characterized by its

magnitude and duration. But some researches have shown that other

parameters such as phase angle jump, point on wave, waveform distortion

and phase imbalance could also affect the performance of some sensitive

equipments.

Many researchers are characterizing and detecting voltage sags by

using the latest signal processing algorithm such as [6], [7] had proposed