vi
TABLE OF CONTENTS
CHAPTER
1
2
TITLE
PAGE
DECLARATION
ii
ACKNOWLEDGEMENT
iii
ABSTRACT
iv
ABSTRAK
v
TABLE OF CONTENTS
vi
LIST OF TABLES
vii
LIST OF FIGURES
ix
LIST OF SYMBOLS
xii
LIST OF APPENDICES
xiv
INTRODUCTION
1.1 Project Background
1
1.2
Objective of Project
3
1.3
Scope of Project
4
1.4
Outline of the thesis
4
REVIEW OF VOLTAGE SAGS
2.1
Introduction
7
2.2
Causes of voltage sags
7
2.2.1
System faults
9
2.2.2
Operation of reclosure and circuit
10
breaker
2.2.3
Equipment failure
10
2.2.4
Bad weather
11
2.2.5
Pollution
11
2.2.6
Animal and birds
11
vii
2.2.7
Vehicle problem
12
2.2.8
Construction activity
12
2.2.9
Capacitor switching
12
2.3 Categories and characteristics
2.3.1
12
Voltage sags characteristics
14
2.3.1.1
Sag magnitude
15
2.3.1.2
Sag duration
15
2.3.1.3
Phase angle jump
15
2.4
The reference standard
16
2.5
Voltage sags monitoring
21
2.5.1
Power system design
25
2.5.2
Equipment design
26
2.5.3
Power conditioning equipment
26
2.6
Detection methods
23
2.6.1
RMS value evaluation method
27
2.6.2
Peak technique evaluation method
27
2.6.3
Missing voltage technique
27
2.7
The analysis
28
2.8
Mitigation equipments
29
2.8.1
Voltage sags mitigation technique
30
2.8.1.1
30
Thyristor
based
static
switch
2.8.1.2
Energy storage system
31
2.8.1.3
Dynamic voltage regulator
32
electronic tap changing
transformer
2.8.1.4
3
Static VAR compensator
32
RESEARCH METHODOLOGY
3.1 Method
34
3.2 Modelling of the plant
40
3.2.1
Short line model for cables
40
3.2.2
Transformer modelling
41
viii
3.2.3
4
Plant load
RESULT, ANALYSIS AND DISCUSSION
4.1 Preliminary
46
4.2 Result
51
4.3 Mitigation
55
4.3.1
55
Proposal of mitigation
4.4 Discussion of results
5
43
58
CONCLUSION
5.1 Conclusion
60
5.2 Recommendation of future work
61
REFERENCES
64
Appendices A-J
66-85
ix
LIST OF TABLES
TABLE NO.
1.1
TITLE
Voltage sags counts in a cement manufacturing plant
PAGE
2
causing plant interruption
2.1
Categories and typical characteristics of Power System
13
Electromagnetic Phenomenon
2.2
Examples of average voltage dip performance from major 19
Benchmarking projects. These values represent voltage
dip performance on medium voltage systems
2.3
Recommended magnitude and duration categories for
Calculating voltage dip performance
20
2.4
Power quality mitigation equipment
29
2.5
Characteristic of various energy storage devices
31
3.1
SARFI results for Rawang Plant under study
36
3.2
Cable impedances
41
3.3
Power measurement of the plant load no.1-6 in feeder 1
And no.7-11 in feeder 2
44
4.1
Summary of voltage sag causing the plant to trip.
Marked in green is the highest voltage sag level
47
4.2
Comparison of price
58
5.1
Comparison between pull-in and holding VA
61
5.2
Sample result and comparison with standard reference
62
x
LIST OF FIGURES
FIGURE NO.
TITLE
PAGE
2.1
Typical voltage sag
7
2.2
Instantaneous voltage sag caused by SLG fault
7
2.3
Temporary voltage sag caused by motor starting
8
2.4
Fault on the network, affected the other lines
10
2.5
Rectangular voltage sag characteristics
14
2.6
1996 Version of the IT Industry Tolerance Curves
17
2.7
The SEMI F47 voltage sag ride-thru curve
18
2.8
Voltage sag during a remote fault
22
2.9
RMS variation magnitude duration scatter plot
24
2.10
Customer area of vulnerability
25
3.1
TNB 132KV grid transmission network received by
Rawang Plant (APMR in RED)
35
3.2
Methodology of the study
37
3.3
MATLAB Simulink model of the plant incoming 1 and 2
132KV, 2MVA transformer with 3 phase fault
39
3.4
Short line model
40
4.1
Voltage sag/swell for incomer 1 recorded since
October 2004
49
4.2
Voltage sag for incomer 1 recorded since October 2004
49
4.3
Voltage sag/swell for incomer 2 recorded since
October 2004
50
xi
4.4
Voltage sag for incomer 2 recorded since October 2004
50
4.5
Voltage sags detected from simulation model of the
plant with fault resistance R=1Ω at B11 location
51
4.6
Magnitude of 3-phase fault at B9
52
4.7
Output of 3-phase fault at B10
52
4.8
Output of 3-phase fault at B11
53
4.9
Output of 3-phase fault at B12
53
4.10
Output of 3-phase fault at B13
54
4.11
Output of 3-phase fault at B14&B15
54
4.12
Backup supply injected to system for Preheater fan B
during voltage sag
56
4.13
VabcB5 line injected with back-up supply and
compared to others voltage sag without back-up
57
5.1
Schematic of control circuit test with sag generator to
Test the control system
62
5.2
Control diagram of Preheater fan A&B and proposed
mitigation to protect control supply from voltage sags
63
xii
LIST OF SYMBOLS
p.u
-
per unit
Z
-
Impedance
R
-
Resistance
L
-
Inductance
l
-
Line length
RT
-
Resistance at T temperature
α
-
Coefficient for copper, 0.00381
XL
-
Reactance of Inductance
Ω
-
Ohm
f
-
Frequency
H
-
Henry
ZT
-
Impedance of transformer
Ukr
-
Impedance voltage %
UrT
-
Rated voltage
SrT
-
Rated apparent power
RTx
-
Transformer resistance
URr
-
Transformer impedance %
UrT
-
Rated voltage
XT
-
Transformer reactance
Rp.u
-
Resistance in per unit
xiii
Lp.u
-
Inductance in per unit
Rbase
-
Base resistance
Lbase
-
Base inductance
xiv
LIST OF APPENDICES
APPENDIX
TITLE
PAGE
A
Characteristics for cables; resistance per km of
positive sequence system at 20oC in Ω/km
66
B
Characteristics for paper insulated cables; reactance
per unit length of a positive sequence system in Ω/km
67
C
Characteristics for cables; reactance per km of a
positive or sequence system in Ω/km ; using steel
band armouring the reactance are increase by
about 10%
68
D
Characteristics for cables; reactance per km of a
positive or sequence system in Ω/km ; using steel
band armouring the reactance (XLPE) are increase
by about 10%
69
E
Cable calculation for the model
70
F
Characteristics of transformers
71
G
The per unit conversion – Transformer
72
H
Result of Power Quality – Voltage sag/swell for
Incomer 1
74
I
Result of Power Quality – Voltage sag/swell for
Incomer 2
79
J
Magnitude of voltage when applied 3-phase fault
on different location
84