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