DEVELOPMENT OF VOLTAGE SAGS MONITORING AND MITIGATION
ANALYSIS FOR CEMENT MANUFACTURING INDUSTRIES
MOHD AZHAR BIN MOHD NOOR
A project report submitted in fulfilment of the
requirement for the award of the degree of
Master in Engineering (Electrical-Power)
Faculty of Electrical Engineering
Universiti Teknologi Malaysia
MAY 2008
iii
ACKNOWLEDGEMENT
Words cannot express my gratitude towards my supervisor, Dr. Azhar bin
Khairuddin for the patience and advice I received from him in the course of this
project. May the sky be your limits in all your future endeavours and only Allah
SWT can repay the kindness.
My gratitude also to Lafarge Malayan Cement, for providing the opportunity
and time in completion of the project, and as the source of the study. Also I would
like to heartily thank the Tenaga National Berhad Energy Services, especially
En.Hamdan and En.Effi for their assistance for site test and monitoring. Without
them the whole project is incomplete.
Finally, my acknowledgment to my family and friend who directly or
indirectly involved in the project for their support.
iv
ABSTRACT
Supply voltage sags are one of the power quality problems, which have
become a big concern in the recent years. In all types of networks; industrial,
commercial and residential, various load devices are utilised, which are very
sensitive to voltage sags like examples electronic controls, computers, adjustable
speed drives. Many customer experience severe consequences of voltage sags,
which can prevent appliances from proper operating and make industrial processes,
shut down. An interruption of industrial process due to voltage sag can result in big
economical losses and costs. This project investigates the impact of voltage sags on
the plant operation in a heavy industry electrical network. Understanding the
existing system immunity to voltage sags is essential, and to accomplish that,
MATLAB Simulink was used. Actual plant load flow is modelled and simulation
result analysed. Area of vulnerability has been determined and system level of
sensitivity has been developed. Result shows that equipments weakness not due to
voltage sags at 11kV, but mainly due to failure of lower voltage; i.e. control voltage
to hold operation during voltage sags. Further investigation is recommended on the
low voltage level. From the investigation, proposed mitigation has been suggested
and verified by simulation technique.
v
ABSTRAK
Bekalan voltan lendut adalah salah satu daripada masalah kualiti
kuasa, dimana masalah ini telah menjadi semakin membimbangkan dalam tahuntahun kebelakangan ini.
Didalam pelbagai system jaringan elektrik; industri,
komersil dan domestik, pelbagai jenis beban peralatan digunakan, dimana peralatanperalatan itu sangat sensitif kepada voltan lendut contohnya seperti kawalan
elektronik, komputer, kawalan kelajuan berubah-ubah. Terdapat ramai pengguna
mengalami kesan negatif akibat daripada voltan lendut, yang menyebabkan
peralatan-peralatan tidak dapat beroperasi dan proses-proses industri terhenti.
Sebarang ganguan kepada proses industri yang disebabkan oleh voltan lendut boleh
menyebabkan kerugian yang besar dan peningkatan kos. Projek ini mengkaji kesan
voltan lendut kepada jaringan elektrik bagi operasi sebuah industri berat. Bagi
tujuan itu, kita perlu memahami kedaan sebenar imuniti system kepada voltan
lendut, dan untuk menjayakannya, program MATLAB Simulink telah digunakan.
Keadaan sebenar aliran beban dimodelkan dan keputusan simulasi dianalisa.
Kawasan yang mudah menerima kesan voltan lendut dan aras kesensitifan system
akan diketahui. Hasil kajian memunjukkan bahawa kelemahan peralatan bukan
kerana voltan lendut pada 11kV, tetapi kegagalan pada voltan lebih rendah;
contohnya voltan kawalan untuk mengekalkan operasi semasa voltan lendut. Kajian
diperingkat voltan yang lebih rendah dicadangkan untuk diteruskan. Berdasarkan
kajian yang dilakukan, cadangan untuk mengatasi masalah ini telah di tunjukkan
dengan teknik simulasi.
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
CHAPTER 1
INTRODUCTION
1.1
Project background
Cement manufacturing is a heavy industries which involved various types of
electrical equipments from high voltage power supplies to control system i.e. DCS,
PLC, Computers, to control a complex process. Cement plant is an integrated
system where if any of the machine in the loop stop, will cause total process
interruption. Hence, short duration of power quality is enough to cause interruption
to the whole operation, losses is significant, and detection and mitigation will save
million of Ringgit in company revenue.
A cement manufacturing facilities in Rawang, Selangor is the main source of
the study. Almost all the power quality events experience by the plants is voltage
sags. Since year 2000, the plant experience 42 numbers of voltage sag conditions
which those causing electrical equipments to trip and consequently stop the plant.
2
Table 1.1 is the summary of Voltage Sag counts in Cement Manufacturing
Plant in Rawang plant since 2000[1]:
Table 1.1
Voltage sags counts in a cement manufacturing plant causing plant
interruption.
Year
Voltage Sag Count
Est. Losses (RM)
2000
10
518,480
2001
8
1,050,257
2002
2
174,539
2003
5
166,500
2004
5
213,044
2005
8
422,000
2006
4
367,430
2007 (Till Mar07)
1
66,755
TOTAL
43
2,979,005
AVERAGE
6/year
69,279/incident
The above losses only count the opportunity losses and fuel cost taken to
restart heating process before production will resume. But, there is many other
losses not counted above i.e. material wastages, extra electricity cost incurred, extra
overhead incurred, equipments damages, environmental impact (tripping causing
release emission to environment).
The sources of voltage sags can be internal or external in view of the
industrial plant, voltage sags can occur on utility system (Tenaga National Berhad in
Malaysia) both at distribution voltages and transmission voltages. Voltage sags that
occur at higher voltages will normally spread through a utility system and will be
transmitted to lower voltage systems via transformers. Voltage sag can be created
within an industrial complex without any influence from the utility system. These
sag typically caused by starting large motors or by electrical faults inside the facility.
3
Frequently industrial customers blame their local electrical utility for
unplanned production stoppages and claim that other jurisdictions have much better
power quality. Unfortunately in many cases there is little or nothing the utility can
do and very few utilities, anywhere in the world, escape voltage sags.
Since the utility faults cannot be eliminated completely, solution to sag
problems must always be tackled at the customer facility; accurate estimates of sag
characteristics can help the facility personnel to take decision on purchasing power
quality mitigation equipment [2].
1.2
Objectives of project
The objectives of the project are as follows:
1.2.1
To develop a systematic method in monitoring, detection and data
interpretation related to voltage sag problems in general and cement
manufacturing industries in particular.
1.2.2
To model the actual cement manufacturing plant for voltage sag analysis
and proposed mitigation methods.
1.2.3
To verify the result with the incoming supply Power Quality monitoring
devices to determine sensitive equipments.
4
1.3
Scope of project
The project focuses on voltage sags detection and mitigation specific to the
actual cement manufacturing industries electrical network. The electrical network or
distribution system is modelled to understand the impact of voltage sag to plant
electrical network and the equipment or area of vulnerability to voltage sag will be
determined. Detection of voltage sags by simulation of fault, mainly single to
ground or three phase fault, and result is analysed for sensitivity of the plant
network.
Proposed mitigation technique is based on cost efficiency and
functionality and selection of mitigation method based on existing technology
available, and do not include detail design.
1.4
Outline of the thesis
The thesis consists of 5 chapters. In chapter 2, a brief review of
voltage sags related to the project is discussed, where definition, sources of
voltage sags, characteristics, reference standard, detection methods and
mitigation available explained.
In chapter 3, research methodology is proposed, MATLAB Simulink
is the software used to study the load flow and analysis of voltage sags.
Source of voltage sags is 3-phase fault with assumption of no loading
changes during the analysis, and a typical load condition is used through out
the analysis. Explanation on how the equipments are modelled also detailed
in this chapter.
In chapter 4, result of the analysis is discussed, and all relevant
information is compared to understand the equipments behaviours during
voltage sags. From the analysis we managed to understand the bigger
pictures if voltage sags impact on the plant operations, and stages of
mitigation could be proposed.
5
Conclusion of the project is explained in chapter 5, where the project
considered successful of achieving the objectives and actual proposal being
implemented in the plant as a result of the study.
CHAPTER 2
REVIEW ON VOLTAGE SAGS
2.1
Introduction
Voltage sags or dips which are the same, a decrease to between 0.1 and 0.9
pu in rms voltage or current at the power frequency for durations of 0.5 cycles to 1
min.
Typical values are 0.1 to 0.9 pu. [2] (IEEE Std. 1159-1995 IEEE
Recommended Practice for Monitoring Electric Power quality) are brief reductions
in voltage, typically lasting from a cycle to a second or so, or tens of milliseconds to
hundreds of milliseconds.
Voltage sags are caused by abrupt increases in loads such as short circuits or
faults, motors starting, or electric heaters turning on, or they are caused by abrupt
increases in source impedance, typically caused by a loose connection. Figure 2.1
below shows typical voltage sag waveform captured, it can be seen clearly where the
voltage
falls
below
the
nominal
voltage
during
normal
conditions.
7
Figure 2.1
Typical voltages sag
Voltage sags are usually associated with system faults but can also be caused
by the switching of heavy loads or the starting of large motors. Figure 2.2 shows
typical voltage sag that can be associated with a single line-to-ground (SLG) fault.
Also, a fault on a parallel feeder circuit will result in a voltage drop at the substation
bus, which affects all of the other feeders until the fault is cleared. Typical fault
clearing times range from three to thirty cycles depending on the fault current
magnitude and the type of overcurrent detection and interruption.
Figure 2.2
Instantaneous Voltage Sag Caused by a SLG Fault
Large load changes or motor starts can also cause voltage sags. An induction
motor will draw six to ten times its full load current while starting. This lagging
current then causes a voltage drop across the impedance of the system. Should the
current magnitude be large relative to the system available fault current, the resulting
8
voltage sag may be significant. Figure 2.3 illustrates the effect of a large motor
being started.
Figure 2.3
2.2
Temporary Voltage Sag Caused by Motor Starting
Causes of voltage sags
Voltage sags can be divided into three classes: fault-induced, transformer
saturation and induction motor starting. Fault induced sag are a major concern
because they might be severe and cause problem to several types of equipment.
Transformer saturation might occur during energizing or changes in the voltage at
the transformer terminals. It causes non-rectangular voltage sags and temporary
harmonic distortion.
Induction motor starting especially using Direct-On-Line
(DOL) system draw high current in a short period of time and causing sags, but
normally limited to 80% where most equipment able to withstand the dips [3].
9
There are many causes of voltage sags that can be listed and explained as
below:
2.2.1
System faults
i.
SLG – Single line-to-ground fault, fault at parallel feeder
cause voltage drop at the substation bus which affect all
the other feeders until the fault is cleared.
Typical fault
clearing time range from 3-30 cycles (1 cycle =
0.02second) depending the fault current magnitude and
type of the over current detection and interruption. The
most common voltage sags, over 70% are single phase
events which are typically due to phase to ground fault
occurring somewhere on the system. The phase to ground
fault appears as a single-phase voltage sag on other
feeders from the same substation.
Typical causes are
lightning strikes, tree branches, animal contact and others.
It is not uncommon to see single-phase voltage sags to
30% of nominal voltage are usually confined to an
industrial plant or its immediate neighbours [3].
ii.
Phase to phase - 2 phases, phase-to-phase sags may cause
by tree branches, adverse weather, animal or vehicles
collision with utility poles. The two phase voltage sag
will typically appear on other feeders from the same
substation
iii.
3 phase - Symmetrical 3 phase sags account for less than
20% of all sag events and are caused either by switching
or tripping of a 3 phase circuit breaker, switch or recloser
which will create a 3 phase voltage sag on other lines fed
from the same substation. 3 phase sags will also cause by
starting large motors but this type of event typically
causes voltage sags to approximately 80% of nominal
10
voltage and is usually confined to an industrial plant or its
immediate neighbours.
2.2.2
Operation of re-closers and circuit breakers
If substation circuit breaker or recloser is tripped, then the line it is feeding
will temporarily disconnected. All other feeder lines from the same substation
system will see this disconnection event as a voltage sags; which will spread to
consumers on these other lines. This can be explained in figure 2.4 where fault
occurs at line 1 and the voltage sags can be seen at other lines.
Figure 2.4
2.2.3
Fault on the network, Line 1, affected the other lines
Equipment failure
If the electrical equipment fails due to the overloading, cable faults and
others, protective equipment will operate at the substation and other feeders will see
voltage sags.
11
2.2.4
Bad weather
Thunderstorms and lightning strikes cause a significant number voltage sags,
If lightning strikes a power line and continues to ground, this creates a line to ground
fault. The line to ground fault in turn creates a voltage sag and this reduce voltage
can be seen over a wide area. Circuit breakers and reclosers operate more frequently
in poor weather conditions. High wind can blow tree branches into power lines. As
the tree branch strike the line, a line to ground fault occurs which create voltage sag.
If the line protection system does not operate immediately, s series of voltage sag
will occur if the branch repeatedly touches the power line. Broken branches landing
on power lines cause phase to phase and phase to ground faults. Snow and ice build
up on power line insulators can cause flashover, either phase to ground or phase to
phase. Similarly for snow ice falling on one line can cause it to rebound and strike
another line. These events cause voltage sags to spread through other feeders on the
system.
2.2.5
Pollution
Salt spray build up on power line insulators over time in coastal areas, even
many miles inland, can cause flash over especially in stormy weather. Dust in arid
inland areas can cause similar problems.
As circuit protector devices operate,
voltage sags appear on other feeders.
2.2.6
Animal and birds
Animal particularly squirrels, racoons and snakes occasionally find the way
onto power lines or transformers and cause short circuit either phase to phase or
phase to ground. Large birds, geese and swans, fly into power lines and cause
similar faults. While the creature rarely survives, the protective circuit breaker
operates and voltage sag is created on other feeders.
12
2.2.7
Vehicle problem
Utility power lines frequently run alongside public road.
Vehicles
occasionally collide with utility poles causing lines to touches, protective devices
trip and voltage sags occurs
2.2.8
Construction activity
Even when all power lines are underground, digging foundations for new
building construction can result in damage to underground power lines and create
voltage sags.
2.2.9
Capacitor switching
Capacitor causes high frequency oscillatory transients that are superimposed
to the voltage waveform. The over voltage that is caused is usually between 1.1 and
1.7 p.u. and the frequency of oscillation between 300Hz and several thousand Hz.
2.3
Categories and characteristics
The term sag has been used in the power quality community for many years
to describe a specific type of power quality disturbance known as a short duration
voltage decrease. Clearly, the notion is directly borrowed from the literal definition
of the word sag. The IEC definition for this phenomenon is dip. The two terms are
considered interchangeable, with sag being preferred in the United States power
quality community.
Previously, the duration of sag events has not been clearly defined. Typical
sag durations defined in some publications range from two milliseconds (about one-
13
eighth of a cycle) to a couple of minutes. Under voltages that last less than one-half
cycle cannot be characterized effectively as a change in the rms value of the
fundamental frequency value. Therefore, these events are considered transients.
Undervoltages that last longer than one minute can typically be controlled with
voltage regulation equipment and may be associated with a wide variety of causes
other than system faults.
Voltage sag durations are subdivided here into three categories -instantaneous, momentary and temporary -- coinciding with the three categories of
interruptions and swells. These durations are intended to correlate with typical
protective device operation times as well as with duration divisions recommended
by international technical organizations. These three different definitions of sags are
defined by their duration and shown in Table 2.1 below.
Table 2.1
Categories and Typical Characteristics of Power System
Electromagnetic Phenomenon
Categories
Typical Duration Typical Voltage Magnitude
2.0 Short Duration Variations
2.1 Instantaneous
2.1.1 Sag
0.5 – 30 cycles
0.1 - 0.9 pu
2.1.2 Swell
0.5 – 30 cycles
1.1 - 1.8 pu
2.2.1 Interruption
0.5 cycles - 3 s
<0.1 pu
2.2.2 Sag
30 cycles - 3 s
0.1 - 0.9 pu
2.2.3 Swell
30 cycles - 3 s
1.1 - 1.4 pu
2.3.1 Interruption
3 s – 1 min
<0.1 pu
2.3.2 Sag
3 s – 1 min
0.1 - 0.9 pu
2.3.3 Swell
3 s – 1 min
1.1 - 1.2 pu
2.2 Momentary
2.3 Temporary
14
2.3.1
Voltage sags characteristics
As mention above, there are 3 types of voltage sags, and fault-induced sags is
the major concern and in this project, we only focussing on this type of fault as our
source of sags. In the occasion of a fault, voltage drop very fast and remains almost
constant to a new lower value until protection operates to clear the fault creating an
almost rectangular shape for the RMS voltage. The characteristics of such sags are
shown in Figure 2.5 for an ideal voltage waveform (pure sinusoid, no harmonic) [4].
These are:
i.
Voltage sag magnitude (Ar-Ad).
ii.
The change in the phase (phase angle jump) with respect to a
reference voltage.
iii
The point on the wave from where the sag starts.
Figure 2.5
Rectangular voltage sag characteristics
Better understanding of the voltage sag characteristics of the electrical
supply system offers the opportunity to evaluate alternate system configuration, and
small modifications in equipment specifications can reduce the number of nuisance
15
outages due to voltage sag. Hence there are definite needs for utilities companies to
provide more information regarding voltage sags to their customer in today’s
competitive environment.
Voltage sags can be characterized by their magnitude (voltage during the
fault) and their duration. The magnitude is determined by the electrical distance to
the fault and duration of by fault clearing time. Magnitude and duration are two
essential characteristics that determine the equipment behaviour.
2.3.1.1
Sag magnitude
It is the net rms voltage during the fault, in percent or in per unit value of
system nominal voltage.
Field surveys have shown that the sag magnitude is
relatively constant during the fault [5].
2.3.1.2
Sag duration
Sag duration is the time the voltage is low, usually less than 1 second. The
sag duration is depending on the over current protection equipment and how long the
fault current is allowed to flow. There are many types of fault clearing equipment
and each has an absolute minimum time that it takes to clear fault. In addition,
intentional time delay is commonly introduced to provide coordination between
devices connected in series.
2.3.1.3
Phase angle jump
A short circuit (or a fault) in a power system not only leads to a drop in
voltage magnitude, but also to a change in phase angle of the voltage (i.e. jump in
phase angle). This so-called phase angle jump (i.e. the phase angle between: during
sag and pre-sag voltages) can be calculated as the argument of the complex voltage
sag Vsag. Magnitude and phase angle jump of sags are directly related to the
voltage in the faulted phase, or between the faulted phases, at the point of common
coupling (PCC) between the load and fault.
16
2.4
The reference standard
Voltage sags are the most common power disturbance.
At a typical
industrial site, it is not unusual to see several sags per year at the service entrance,
and far more at equipment terminals. Voltage sags can arrive from the utility;
however, in most cases, the majority of sags are generated inside a building. For
example, in residential wiring, the most common cause of voltage sags is the starting
current drawn by refrigerator and air conditioning motors.
Sags do not generally disturb incandescent or fluorescent lighting, motors, or
heaters.
However, some electronic equipment lacks sufficient internal energy
storage and, therefore, cannot ride through sags in the supply voltage. Equipment
may be able to ride through very brief, deep sags, or it may be able to ride through
longer but shallower sags.
Figure 2.6 below is 1996 version of the IT Industry
Tolerance Curves (update from original CBEMA curve). The vertical axis is percent
of nominal voltage. "Well-designed" equipment should be able to tolerate any
power event that lies in the shaded area. Note that the curve includes sags, swells,
and transient over voltages.
17
Figure 2.6
1996 Version of the IT Industry Tolerance Curves
The semiconductor industry developed a more recent specification (SEMI
F47) for tools used in the semiconductor industry in an effort to achieve better ride
through of equipment for commonly occurring voltage sags and therefore improving
the overall process performance. It is basically the same as the ITI Curve but
specifies an improved ride through requirement down to 50% retained voltage for
the first 200-msec. See figure 2.7 for SEMI F47 details. Many short voltage sags
are covered by this additional requirement. IEC 61000-4-11 and IEC 61000-4-34
provide similar voltage sag immunity standards.
18
Figure2. 7
The SEMI F47 voltage sag ride-thru curve
Many utilities have benchmarked performance of the supply system for
voltage sags but it has not been the general practice to specify any required
performance levels for the system. Performance is often specified using the SARFI
index that provides a count of all events with magnitudes and durations outside of
some specifications. For instance, SARFI-70 would provide a count of all voltage
dips with a retained voltage less than 70% (regardless of duration). SARFI-ITIC
would provide a count of all voltage dips that exceeded the ride through
specifications of the ITI Curve.
Table 2.2 provides a summary of voltage dip performance levels from a few
major benchmarking efforts. Note that these are average performance levels and it
would not be reasonable to develop limits based on an average expected
performance (although these are the correct values to use when evaluating the
economics of investments in ride through solutions).
19
Table 2.2
Example of average voltage dip performance from major
benchmarking projects. These values represent voltage dip performance on medium
voltage systems.
The voltage sag performance can vary dramatically for different kinds of
systems (rural vs. urban, overhead vs. underground). It may be important to include
some of these important factors in the specification of the power quality grades.
It will also be important to specify the performance for momentary
interruptions. These events can be a particular problem for customers and are not
included in most assessments of reliability.
A previous CEA Technologies report prepared by Electrotek Concepts [6]
recommended that the SARFI indices be calculated for the following magnitude and
duration categories as mention in Table 2.3
20
Table 2.3
Recommended magnitude and duration categories for calculating
voltage dip performance.
The reasons for these categories were explained as follows:
i.
The 90% level provides an indication of performance for the most sensitive
equipment.
ii.
The 80% level corresponds to an important break point on the ITI curve and
some sensitive equipment may be susceptible to even short sags at this level.
iii.
The 70% level corresponds to the sensitivity level of a wide group of
industrial and commercial equipment and is probably the most important
performance level to specify.
iv.
The 50% level is important, especially for the semiconductor industry, since
they have adopted a standard that specifies ride through at this level.
Interruptions affect all customers so it is important to specify this level
separately. These will usually have longer durations than the voltage sags. The first
range of durations is up to 0.2 seconds (12 cycles at 60 Hz). This is the range
specified by the semiconductor industry that equipment should be able to ride
through sags as long as the minimum voltage is above 50%. The second range is up
to 0.5 seconds. This corresponds to the specification in the ITIC standard for
equipment ride through as long as the minimum voltage is above 70%. It is also an
important break point in the definition of sag durations in IEEE 1159 (instantaneous
21
vs. momentary). The third duration range is up to 3 seconds. This is an important
break point in IEEE 1159 and in IEC standards (momentary to temporary). The
final duration is up to one minute. Events longer than one minute are characterized
as long duration events and are part of the system voltage regulation performance,
rather than voltage sags.
2.5
Voltage sags monitoring
Voltage variations, such as voltage sags and momentary interruptions are two
of the most important power quality concerns for customers. Customers understand
that interruptions cannot be completely prevented on the power system. However,
they are less tolerant when their equipment misoperates due to momentary
disturbances which can be much more frequent than complete outages.
These
conditions are characterized by short duration changes in the rms voltage magnitude
supplied to the customer. The impact to the customer depends on the voltage
magnitude during the disturbance, the duration of the disturbance, and the sensitivity
of the customer equipment.
Voltage variations and interruptions are inevitable on the power system. The
most important of these variations occur during fault conditions on the power
system. Since it is impossible to eliminate the occurrence of faults, there will
always by voltage variations.
This section describes some of the concerns
associated with short duration voltage sags and interruptions.
Power quality
complaints occur either when the customer has equipment that is very sensitive to
these voltage sags (e.g., waveform below) and is critical to the overall process or
when the frequency of occurrence of the interruptions or sags is interpreted as being
unacceptable.
22
On the utility system, protective systems are designed to limit damage
caused by unusual events like faults or lightning strikes, and to localize the impact of
such events to the smallest number of customers.
This is accomplished with
overcurrent protection devices, such as reclosers, sectionalizers and fuses. Figure 2.8
shown an examples of the voltage sag during the remote fault.
Figure 2.8
Voltage Sag during a Remote Fault
IEEE Std. 1159-1995, Recommended Practice on Monitoring Electric Power
Quality, provides definitions to label an rms voltage disturbance based upon its
duration and voltage magnitude [7]. Short duration rms variations are divided into
the instantaneous, momentary, and temporary time periods, while the voltage
magnitude of the disturbance characterizes it as a sag, swell, or interruption. A long
duration rms voltage variation is defined to last longer than one minute, and can be
classified as a sustained interruption, undervoltage, or overvoltage depending upon
its magnitude.
23
Voltage sags and momentary interruptions have always existed on the power
system. In the past, there were not many complaints about these conditions because
residential customers had analog clocks and industrial customers had standard
induction motors. Now, residential customers have digital clocks, VCRs, electronic
coffee makers, and many other electronic gadgets that rely on continuous power to
operate correctly. Every time there is a momentary interruption, many of these
devices lose their settings and must be reset manually.
Industrial customers also have numerous loads that can be sensitive to
voltage sags and momentary interruptions. Voltage sags are the most important
power quality problem experienced by most industrial customers. Adjustable-speed
drive (ASD) controls, robotics, programmable logic controllers, and even contactors
for motor controllers and other control applications will have problems with voltage
sag conditions.
Whether or not a problem exists depends on the magnitude and duration of
the voltage sag. Much of this equipment is used in applications that are critical to an
overall process, resulting in very expensive downtime whenever the voltage sag
condition occurs. Figure 2.9 shows the voltage magnitude and time and location of
fault compared to the CBEMA curve, if the fault fall within the curve, hence the
system will should still operated and safe from the sags, otherwise system
interrupted.
24
Figure 2.9
RMS Variation Magnitude Duration Scatter Plot
It is important for customers to understand the sensitivity of their equipment
to momentary interruptions and voltage sags.
The trip thresholds of sensitive
equipment can often be modified, either with available settings in the controls or by
manufacturer design changes. Once the sensitivity of equipment is known, an area
of vulnerability for faults on adjacent feeders can be identified. This will help in
evaluating the likelihood of problems due to utility system faults. The area of
vulnerability concept can also be applied to customers supplied from the
transmission system. Figure 2.10 shows an area of vulnerability diagram for a
customer supplied from a transmission system bus. The figure shows that the area
of vulnerability is dependent on the sensitivity of the equipment. Contactors that
drop out at 50% voltage will have a relatively small area of vulnerability while
ASDs that drop out at 90% voltage may be sensitive to faults over a wide range of
the transmission system.
25
Figure 2.10
Customer Area of Vulnerability
There are three levels of possible solutions to voltage sag and momentary
interruption problems:
2.5.1
Power System Design
Faults on the power system are the ultimate cause of both momentary
interruptions and voltage sags. Any measures taken to reduce the likelihood of a
fault will help reduce the incidence of sags and interruptions to customers. These
measures can include using underground circuits, tree trimming, and increased
application of surge arresters for lightning protection on distribution circuits. On
transmission circuits where lightning may be the most prevalent cause of faults,
reducing tower footing resistances is one of the measures that can improve the
lightning performance of lines.
26
2.5.2
Equipment Design
It is possible to make the equipment being used in customer facilities less
sensitive to voltage sags and momentary interruptions. Clocks and controls with
low power requirements can be protected with a small battery or large capacitor to
provide ride through capability. Motor control relays and contactors can be selected
with less sensitive voltage sag thresholds. Controls can be set less sensitive to
voltage sags unless the actual process requires an extremely tight voltage tolerance.
This solution requires coordination with equipment manufacturers but the trend
seems to be in the direction of increased ride through capability.
2.5.3
Power Conditioning Equipment
This option involves the addition of power conditioning equipment at the
individual loads that are sensitive to voltage sags and/or interruptions. The power
conditioning requirements depend on the types of voltage sags that can be expected
and the possible durations of interruptions.
2.6
Detection method
Voltage detection is important because it determines the dynamic
performance of the voltage sag regulator. Precise and fast voltage detection is an
essential part of the voltage sag compensator. Some of the available detection
methods are [8]:
27
2.6.1
RMS Value Evaluation Method by S.M.Deckmann and A.A. Feriera
(2002)
RMS value continuously calculated for a moving window of the input
voltage samples, provide a convenient measure of the magnitude evolution, because
they express energy content of the signal. Disadvantage of the detection is based on
averaging of previously sampled data for 1 cycle, hence represents one cycle
historical average value, not momentary value causing error in duration of sags.
2.6.2
Peak technique evaluation method by C.Hui-Yung, J.Hurng-Lianhng
and H.Ching-Lien (1992)
Single-phase line-to-neutral voltage is measured, and the cosine value of the
voltage is determined using a 90o phase shifter. Assuming a fixed value of 50Hz for
line frequency, the 90o-shifted value can be found by either an analog circuit or by
digital signal processing. Both components squared and summed to yield Vp2.
Obtaining the square root of Vp2 results in the peak value of the detected voltage.
Disadvantage of the technique is detection started at the peak value, not at the
beginning of the sags.
2.6.3
Missing voltage technique by N.S.Tunaboyle, E.R. Collins and P.R.
Chaney (1998)
Comparing the difference between the desired instantaneous voltage (preevent) and the actual instantaneous value (event). The technique give more accurate
indication of the duration of the event but if line voltage is abnormal, the disturbance
exist will also lead to incorrect switchover of compensator. So it is necessary to add
dead time and hysteresis band.
28
In this project, we use missing voltage technique for the measurement of the
voltage sags. Since the pre-event voltage will be the same through out the analysis
as using simulation we need to maintain the load to obtain similar initial conditions.
2.7
The analysis
Voltage sag analysis is the process of determining the number (and severity)
of voltage sags that affect end-use equipment. It takes into account utility fault
performance, the utility network, transformations to end-use equipment, and
equipment connections in predicting the voltage sags that will occur.
Voltage sag analysis is useful to electric utilities for predicting power quality
levels at new or existing industrial/commercial sites being constructed or to user to
understand their equipments immunity.
The utility can predict in advance the
expected power quality level, allowing their customer to be more proactive in
specifying solutions to voltage sags as the facility is being built. It also allows
electric utilities to determine the effect of network changes and their impact
(potential improvement) on customer power quality levels. For example, adding
generation can result in fewer (less severe) voltage sags at nearby customers.
Changing the configuration of tie switches, or adding transmission lines can also
impact performance.
Voltage sag analysis is useful to large industries and commercial customers
to evaluate investments in power quality solutions. Many of the most economical
power quality solutions are solutions that address the most common problem,
voltage sags. Examples of these solutions are Dynamic Voltage Sag Correctors
DySC™, Dynamic Voltage Restorer DVR™, and PureWave™. To evaluate the
value of these investments an annual profile of the sites voltage sag performance is
necessary. Voltage sag analysis provides this vital information.
29
Voltage sag analysis is done by compiling the electric utility fault
performance (faults per 100 miles per year) of various classes (voltage levels) of
network. A complete system short circuit analysis is done to determine the voltage
sag resulting from faults across the network. A computerized analysis determines
the annual profile of voltage sags at a given utilization point – taking into
consideration various transformations and equipment connections.
2.8
Mitigation equipments
Mitigation equipment exists for each of power quality problem categories,
and can be seen in table 2.4.
Table 2.4
Problem
Power Quality mitigation equipments
Mitigation device
Voltage transient
Spike
Surge arresters
Oscillation
Lightning arresters
Static switch
Controlled switching
Energy storage system
Voltage sag
Energy storage system
Static switch
Automatic tap changing transformer
Dynamic voltage regulator
Static VAR compensator
Voltage interruption
Momentary
Energy storage system
Sustained
Static switch
Automatic tap changing transformer
Dynamic voltage regulator
30
Static VAR compensator
Regulation
Overvoltage
Automatic tap changing transformer
Undervoltage
Dynamic voltage regulator
Static VAR compensator
Harmonic, notching, noise
Passive filter
Dynamic filter
Static VAR compensator
Flicker
2.8.1
Static VAR compensator
Voltage sags mitigation equipments
2.8.1.1 Thyristor-based static switch
The static switch is a versatile device for switching a new element into the
circuit when voltage support is needed. It has a dynamic response time of about one
cycle. To correct for voltage spikes, sags or interruptions the static switch can be
used to switch in one of the following:
i-
Capacitor
ii-
Filter
iii-
Alternate power line
iv-
Energy storage system
The static switch can be used in the alternate power line application. This
scheme requires two independent power lines from the utility. It protects against
85% of the interruptions and voltage sags. It does not protect against area-wide
disturbances that affect both lines [9].
31
2.8.1.2 Energy storage system
Storage system can be used to protect sensitive production equipment from
shutdowns caused by voltage sags or momentary interruptions. These are usually dc
storage systems, such as UPS, batteries, superconducting magnet energy storage
(SMES), storage capacitors or even flywheels driving dc generators. The output of
these devices is supplied to the system through an inverter, on a momentary basis,
by a fast acting electronic switch. Enough energy is fed to the system to replace the
energy that would lost by the voltage sag or interruption.
Table 2.5 below are the characteristics of various energy storage devices.
Table 2.5
Characteristic of various energy storage devices
Lead acid
Nickel
Sodium
LTS
LTS
GMF,
GMF,
battery
cadmium
sulphur
SMES
SMES
high
low
battery
battery
speed
speed
High
Low
Low
Medium
Low
Medium
High
2 min
2 min
30 min
15s
15s
15s
15s
Efficiency
85%
75%
98%
98%
98%
90%
90%
Losses due
Self
Self
Reaction Heat input
Heat input
Friction
Friction
to
discharging discharging heat
Risks
Acid
Market
readiness
Typical
starting
time
Anticipated 1500
Alkalis
Heat
Quenching Quenching Mass
Bearing
1000
1000
100,000
100,000
1,000,000 1,000,000
133,333
-
666,666
1,000,000
100,000
cycles
Price in
Pound for
1MW
33,333
33,333
32
2.8.1.3 Dynamic voltage regulator / electronic tap changing transformer
A voltage-regulating transformer with an electronic load tap-changer is used
with a single line from the utility. It regulates voltage drops up to 50%. It requires a
stiff system (short-circuit power to load ration10:1 or better). This has coarse steps
and is intended only occasional voltage variations.
There are several manufactures of devices designed specifically for voltage
sag correction in industrial applications. These devices use combination of an
inverter plus short-term electrical storage or an inverter with specially designed
injection transformer to provide voltage correction against voltage sags as they arise.
Typical response times from initiation of a sag to its correction are of the
order of one half cycle or less. Some devices offer limited ride through a zero
voltage event for a short time, others do not. These devices provide excellent
protection against both 3 phases and single-phase voltage sags.
Some manufacturers offer small single-phase devices at low voltage 120V or
220V typically with small KVA rating. Others provide only 3 phase devices at low
voltage 208V-600V and at medium voltage to 36KVA. The KVA ratings of 3 phase
devices typically range from <20KVA – 5MVA at low voltage and from 1MVA to
50MVA for medium voltage applications. A few manufacturer offer solutions in the
50MVA to 100+MVA range at medium voltage but demand for these occurs
infrequently.
2.8.1.4 Static VAR compensator
Loads such rolling mills, mine hoists, cranes, welding machine and arc
furnace, where the use of reactive power changes instantaneously, often cause rapid
voltage fluctuations. If the effects are sufficiently large, production or operational
disturbances can result.
This type of voltage variation can be controlled with
reactive power compensation.
Equipment utilizes a combination of reactors,
capacitors, and, depending on the response time needed, thyristor or IGBT- based
33
controls. Recently, the distribution static synchronous compensator (D-STATCOM)
has been introduced to distribution networks to manage the system reactive power to
regulate the voltage at the distribution buses. A D-STATCOM usually consists of a
voltage source converters (VSC) connected to the grid in shunt. This system can be
used to inject a controllable current into the grid. By injecting current into the point
of common connection (PCC), a shunt-connected VCS can also boost the voltages at
that point during a voltage dip. Furthermore, an unbalance correction can be added
to this function [10].
CHAPTER 3
RESEARCH METHODOLOGY
3.1
Method
The project will propose the method to determine the voltage sags on the
various distribution network of a cement manufacturing industry. The impact of the
voltage sags on the different network locations is studied by using actual plant
model. Modelling of the system can be done using MATLAB SIMULINK software.
Since there is high accuracy online Power Quality monitoring installed since end of
2004 at the main intake (132KV), the result can be used for analysis and
comparison.
The method allows determinating the frequency and severity of voltage sags
that occurs at nodes of the plant electrical network. Types of faults used to simulate
voltage sags are single line-to-ground fault (SLG) and / or three-phase fault.
Loading changes of the system can be neglected in the simulation and assume the
load is maintained during the study.
Compensation is required if the actual pre-event voltage is higher or lower
than the nominal, as this is important to sensitive equipments i.e. ASD, PLCs.
35
Load flow of the system is essential and must be understood, network line
data feeder, feeder sending end voltage at substation, pre-event voltage, load data,
fault impedance and power transformer data are the information required for the
analysis.
Modelling of the plant network is based on the plant single line diagram. The
plant receives 2 incoming supply of 132KV from utilities (TNB) tee-off from KL
North (KULN) to New Rawang (NRWG) and Harta Kemuncak (HKCK) to New
Rawang (NRWG) and each of them will then step down to 11KV by 2 units of
35MVA transformers. This can be seen from Figure 3.1 where the plant under study
marked as APMR.
Load for both supplies are evenly distributed (on full load or
capacity) to ~ 20MVA.
Figure 3.1
TNB 132KV grid transmission network received by Rawang plant
(APMR in RED)
Once the plant is modelled, we then perform the analysis. The voltage sag is
generated by creating short circuit analysis using 3 phase fault and / or SLG faults.
Location of the faults is changed for different bus and the effect on the lines as well
for other lines is monitored; the resultant of the voltage sags, pre-event voltage are
recorded. We consider different value of fault impedance to create different intensity
36
of voltage sags level, and in this project, we use zero to 5Ohm fault impedance and
pre-event voltage of 1.0 p.u.
Voltage sags occurrence and calculation is determined where voltage sags
magnitude and duration is calculated. Results will be compared with the acceptable
standard used i.e. SEMI F47 – 0200, IEC61000-4-11.
Plot the voltage sags characteristics, magnitude and duration for the
conformance to standard. Sensitivity of the equipments is determined from the
results. The similar procedure is repeated for all lines.
Recommendation for
mitigation based on the result. From the plot we able to determine the SARFI
(System Average RMS Variation Frequency Index) and we decided what is the
SARFI level intended. The lower the index will incur more cost.
From the stochastic analysis carried out by TNB Energy Services, where
voltage sag were analysed on the integrated system to identify the annual predicted
voltage sag event at the plant, the result is as per table 5.
Table 3.1
SARFI results for plant under study
37
SARFI is an index counting the number of voltage sag event below certain
levels. For example, SARFI-70 is a number of voltage sag event for voltage sag to
70% and below. Based on the stochastic analysis and existing immunity level of the
sensitive equipment (about 63%), the exposure level towards voltage sag of the
sensitive equipment is about 7 event/year (based on predicted SARFI-60).
Figure 3.2 shows the summary of the methodology of the project in flow
chart.
Start
Understanding Voltage Sags
Concepts
Modelling of the plant’s load flow
Simulation & Voltage Sags
detection
Voltage sag occurrence calculation
Analyse and compilation the result
End
Figure 3.2
Methodology of the study
The project covered from incoming of the plant till the 11kV level except for
2 main step down transformer 11/3.3kV that is installed in the main distribution of
11kV. All the plant network equipments are then converted to SIMULINK model,
this can be seen in figure 3.3. From the model, electrical network under study
received 2 incoming supply 132KV from the different sources. Both incoming then
will be fed to 2 transformer 35MVA to 11KV on secondary that will then distribute
38
through out the plant network to individual substations. The plant using 11KV,
6.6KV and 3.3KV supplies as the medium voltage standard.
39
Figure 3.3
MATLAB SIMULINK model of plant incoming 1 and 2 132KV, 2
35MVA transformers and example of 3 phase faults
40
3.2
Modelling of the plant
3.2.1 Short Line Model for cables
A short line model as figure 3.4 below models the cabling in the plant under
study. Capacitance ignored if lines is less than 80km or if the voltage is less than
69KV [11]. The short line model is obtained by multiplying the series impedance
per unit length by the line length.
Z = (r + jwL)l = R + jX
(1)
Where;
r – per phase resistance
L – Inductance per unit length
l – Line length
IR
Is
+
+
Vs
VR
-
SR
-
Figure 3.4
Short line model
Since the resistance is in 20oC, hence we need to convert the value to
Malaysia temperature condition, and 50oC use as standard industry temperature.
RT = R20 [1 + α(T-20)]
Where;
α - coefficient 0.00381 for copper cable [12]
(2)
41
Cable resistance are given in the Appendix A,B,C and D and different type
of cable i.e. XLPE, PILC are with different resistance [13]. Details calculation can
be viewed in Appendix E.
All the cables impedance then calculated and the value are as table 3.2 below:
Table 3.2
No.
Equipment
Cables impedance, Z
Resistance
Inductance (H/km)
(Ω
Ω/km)
1
Mill house 1
0.11
0.2897x10-3
2
11KV Incomer 1
0.084
0.283x10-3
3
CM5
0.11
0.2897x10-3
4
Limestone mill 1
0.19
0.309x10-3
5
Limestone mill 2
0.19
0.309x10-3
6
Shale mill
0.19
0.309x10-3
7
CM7
0.11
0.2897x10-3
8
Mill house 2
0.11
0.2897x10-3
9
11KV Incomer 2
0.084
0.283x10-3
10
Preheater fan A
0.19
0.3x10-3
11
Preheater fan B
0.19
0.3x10-3
3.2.2 Transformer Modelling
Transformer capacity is 35MVA for the man intake and 10MVA for the
distribution level. 35MVA transformer step down 132KV to 11KV and 10MVA
transformer step down 11KV to 3.3KV. Transformer value is calculated in p.u base.
Impedance, ZT = (UkrxUrT2)
(100%xSrT)
(3)
42
Where;
Ukr – Impedance voltage %
UrT – Rated voltage
SrT – Rated apparent power
And,
Transformer resistance,
RT = (URrxUrT2)
(4)
(100%xSrT)
Where;
URr – Transformer Impedance %
UrT – Rated voltage
SrT – Rated apparent power
And,
Transformer reactance,
XT = √ZT2 + RT2
(5)
Hence,
For 10MVA transformer with
Ukr = 8.19% and URr = 0.7%
ZT = (8.19%x (11x103/√3)2)
(100%x10x106)
= 3.3x106 = 0.33Ω
10x106
and,
RT = (0.7%x(11x103/√3)2) = 282.33x103
6
(100%x10x10 )
10x10
and,
XT = √(0.33)2-(0.028)2 = 0.33Ω
6
= 0.028Ω
43
All the value used for the study is in p.u, calculation can be viewed in
Appendix F and G; for 10MVA transformer, the values are:
Rbase = 4Ω
Lbase = 0.013H
ZT = 0.33Ω
RT = 0.02Ω
XT = 0.33Ω
Rp.u = 0.007
Lp.u = 0.08
The same calculation applies to 35MVA transformer and the values are:
Rbase = 165.94Ω
Lbase = 0.53H
ZT = 0.996Ω
RT = 21.29Ω
XT = 20.3Ω
Rp.u = 0.006
Lp.u = 0.12
3.2.3 Plant Load
The load of the plant is measured by using a power monitor from Allen
Bradley, Model: PM3000. The readings were taken from the feeders, but for the
study, we limit the measurement till 11KV and 2 nos. of 11/3.3KV transformer level
only. The measurement taken is tabulated in the table 3.3.
44
Table 3.3
Power measurement of the plant load, No.1-6 in feeder 1 and No.7-11
in feeder 2
No.
Feeders
Voltage, Power
Apparent
Reactive
(KV)
power
Power
(KVA)
(KVAr)
(KW)
p.f
Current,
Ampere
1
Mill house 1
11,701
1350
1399
440
-0.95
67
2
3.3KV SB 1
3,221
4500
5418
3386
-0.79
978
3
Cement mill 5
11,701
5000
400
-0.94
4
Limestone
11,565
1746
2020
1411
-0.85
105
11,565
1746
2020
1411
-0.85
105
mill A
5
Limestone
mill B
6
Shale mill
11,550
1360
1456
-570
0.93
73
7
Cement mill 7
11,642
4726
-56.9
241
-0.98
239
8
Mill house 2
11,718
2218
2521
1122
-0.89
122
9
3.3KV SB 2
3,239
4500
5420
2966
-0.83
961
10
Preheater fan
11,560
1988
2243
1084
-0.88
112
11,560
1988
2243
1084
-0.88
112
A
11
Preheater fan
B
Since the measurement taken at different time, depending on normal
optimum operation, hence there are some differences in voltage level. The plant
load is assumed stable and same during the analysis. Series RLC load is used with
the reading value as measured above used in power and reactive power.
3.2.4 Voltage sag
The sag created by a 3 phase fault on different lines each time with fault
resistance of 5Ω and reducing 1Ω each time till the lowest ~0Ω (0.001Ω). All the
output result are recorded and monitored.
45
We assume all the voltage sag created is created internally within the plant.
No breaker or protection relay clearance taken into consideration to focus only on
the sensitive areas.
CHAPTER 4
RESULT, ANALYSIS AND DISCUSSION
4.1
Preliminary
Data from the plant Power Quality monitoring that are installed at Incomer 1
and Incomer 2 are shown in Appendix H and I. Power Quality meter is from Power
Measurement, Model: ION7500. But, since the Power Quality meter only installed
on 2004, previous magnitude of the voltage sags are unrecorded. From the data
taken, we summarised in the table 4.1 below where the events recorded in the server
of Power Quality meter are compared to date and time the plant trip and basically we
can conclude that plant will trip for any magnitude less than 68%. This is the
threshold voltage of the plant system.
The record also revealed that that particular equipments namely Preheater
fan A and B always trip for any voltage sag below than 68%. These 2 equipments
are very sensitive to the voltage sags, yet very important for the plant operation.
Any disruption to any of these fans will cause the plant to stop operation
immediately.
The interruption below corresponded with TNB NLDC (National Load
Despatch Centre) on every occasion before we declared as Voltage Dip, and letter of
complaints also send on every interruptions.
47
Table 4.1
Summary of voltage sag causing the plant to trip. Marked in GREEN
is the highest voltage sag level
No
Date
(dd/mm/yy)
Time
Time
tripped
resumed
(hh:mm) (hh:mm)
Estimate
loss (RM)
Supply
status
(On/Off)
Magnitude, Magnitude,
Incomer1 Incomer2
Remarks
1 6/1/2000
12:15pm 12:15pm 40,000
ON
NA
NA
TNB power dip
2 7/1/2000
9:35am
9:35am
40,000
ON
NA
NA
TNB power dip
3 22/3/2000
5:40pm
5:40pm
40,000
ON
NA
NA
TNB power dip
4 2/5/2000
1:40pm
2:20pm
118,800
ON
NA
NA
TNB power dip
5 29/9/2000
6:50pm
6:50pm
132,800
ON
NA
NA
TNB power dip
6 8/10/2000
6:20pm
6:20pm
40,500
ON
NA
NA
TNB power dip
7 9/10/2000
7:02pm
7:20am
46,000
ON
NA
NA
TNB power dip
8 10/10/2000 12:10am 12:10am 12,300
ON
NA
NA
TNB power dip
9 24/10/2000 2:45pm
35,800
ON
NA
NA
TNB power dip
10 27/10/2000 12:35pm 12:35pm 12,280
ON
NA
NA
TNB power dip
11 21/1/2001
8:20pm
8:20pm
31,000
ON
NA
NA
TNB power dip
12 2/2/2001
4:40pm
4:40pm
326,510
ON
NA
NA
TNB power dip
13 18/3/2001
9:45am
9:45am
40,000
ON
NA
NA
TNB power dip
14 31/3/2001
9:15am
9:15am
60,200
ON
NA
NA
TNB power dip
15 5/4/2001
11:40am 11:40am 296,942
ON
NA
NA
TNB power dip
16 13/5/2001
10:15am 10:15am 35,800
ON
NA
NA
TNB power dip
17 1/8/2001
5:20pm
5:20pm
116,321
ON
NA
NA
TNB power dip
18 25/12/2001 4:15pm
4:15pm
143,478
ON
NA
NA
TNB power dip
19 3/5/2002
2:08am
2:08am
74,539
ON
NA
NA
TNB power dip
20 18/9/2002
7:40pm
5:00pm
267,513
OFF
NA
NA
TNB supply outage
21 17/12/2002 4:15am
4:15am
100,000
ON
NA
NA
TNB power dip
2:45pm
22 29/3/2003
12:30pm 12:30pm 40,000
ON
NA
NA
TNB power dip
23 15/5/2003
3:20pm
3:20am
6,500
ON
NA
NA
TNB power dip
24 27/5/2003
4:15pm
4:15pm
40,000
ON
NA
NA
TNB power dip
25 24/9/2003
9:30pm
9:30pm
40,000
ON
NA
NA
TNB power dip
26 8/11/2003
1:00am
1:00am
40,000
ON
NA
NA
TNB power dip
27 25/1/2004
5:50pm
5:50pm
33,800
ON
NA
NA
TNB power dip
28 19/4/2004
8:25am
8:25am
50,869
ON
NA
NA
TNB power dip
29 29/5/2004
3:45pm
3:45pm
40,000
ON
NA
NA
TNB power dip
30 11/11/2004 11:45pm 11:45pm 48,375
ON
55
55
TNB power dip
31 12/11/2004 11:40am 11:40am 40,000
ON
63
63
TNB power dip
32 13/1/2005
ON
64
64
TNB power dip
12:25pm 12:25pm 114,000
48
33 17/4/2005
11:58am 11:58am 44,000
ON
68
68
TNB power dip
34 20/4/2005
1:00pm
1:00pm
44,000
ON
34
34
TNB power dip
35 22/4/2005
6:20pm
6:20pm
44,000
ON
53
53
TNB power dip
36 27/4/2005
2:40am
2:40am
44,000
ON
57
57
TNB power dip
37 2/5/2005
4:20pm
4:20pm
44,000
ON
63
63
TNB power dip
38 25/5/2005
6:45pm
6:45pm
44,000
ON
39
39
TNB power dip
39 4/8/2005
3:00am
3:00am
44,000
ON
11
0
TNB power dip
40 9/2/2006
9:55am
9:55am
28,010
ON
40
40
TNB power dip
41 17/5/2006
6:50pm
6:50pm
80,812
ON
67
66
TNB power dip
42 25/7/2006
7:45am
7:45am
193,683
ON
54
54
TNB power dip
43 12/8/2006
10:24am 10:24am 64,925
ON
53
52
TNB power dip
44 13/1/2007
4:30pm
66,755
ON
44
44
TNB power dip
45 12/5/2007
11:20am 11:20am 34,900
ON
67
67
TNB power dip
4:30pm
46 10/10/2007 3:56am
3:56am
NA
ON
4
4
TNB power dip
47 28/10/2007 4:33pm
4:33pm
NA
ON
61
NA
TNB power dip
48 24/12/2007 4:49pm
4:49pm
NA
ON
4
4
TNB power dip
49 9/1/2008
3:44pm
3:44pm
NA
ON
54
54
TNB power dip
50 4/2/2008
8:57pm
8:57pm
NA
ON
61
61
TNB power dip
3,281,412
From the analysis above, we concluded that voltage sag caused by external
factor that is below than 68% causing interruption to the plant. But, we do not have
or experience any record and/or probably no occasion where internal fault or load
changes causing voltage sag. Then the study should give more attention of the
voltage sag internally.
Figure 4.1 to 4.4 shown the chart of Duration vs. Magnitude for the recorded
data taken from the Power Quality measurement.
49
Voltage Sag/swell for Incomer 1
Magnitude Phase 1
Magnitude Phase 2
Magnitude Phase 3
250
Magnitude (%)
200
150
100
50
0
0
1
2
3
4
5
6
Duration (Sec)
Figure 4.1
Voltage sag/swell for Incomer 1 recorded since October 2004
Voltage Sag/swell for Incomer 1
Magnitude Phase 1
Magnitude Phase 2
Magnitude Phase 3
120
Magnitude (%)
100
80
60
40
20
0
0
50
100
150
200
Duration (ms)
Figure 4.2
Voltage sag for Incomer 1 recorded since October 2004
50
Voltage Sag/swell Incomer 2
Magnitude Phase 1
Magnitude Phase 2
Magnitude Phase 3
140
Magnitude (%)
120
100
80
60
40
20
0
0
1
2
3
4
5
6
7
Duration (Sec)
Figure 4.3
Voltage sag/swell for Incomer 2 taken from October 2004
Voltage Sag/swell Incomer 2
Magnitude Phase 1
Magnitude Phase 2
Magnitude Phase 3
120
Magnitude (%)
100
80
60
40
20
0
0
50
100
150
200
Duration (ms)
Figure 4.4
Voltage sag for Incomer 2 taken from October 2004
51
4.2
Result
From the simulation result of the plant electrical network, the voltage sags
event is recorded of all the possible faults at different branches. The simulation and
analysis only carried out on the Incomer 2 circuit for being sensitive and important
for the plant operation. From the monitoring, we can see the voltage sags events.
See below Figure 4.5 for one of the output result. The results are recorded and
compared to the pre-event voltage and magnitude of the voltage sag is calculated.
As per figure 3.3, a 3-phase fault is applied to a branches 11KV at 0.05s for 0.03
second (11/2cycles) and the voltage monitored with scope.
Figure 4.5
Voltage sags detected from simulation model of the plant with fault
resistance R=1Ω at B11 location
Result of the analysis are compared summarised the Figure 4.6 to 4.11
below.
52
Output of 3phase fault at B9
35
30
Magnitude at B9
Magnitude, %
25
Magnitude at B10
Magnitude at B11
20
Magnitude at B12
15
Magnitude at B13
Magnitude at B14
10
Magnitude at B15
5
0
0
2
4
6
Fault resistance, Ohm
Magnitude of 3-phase fault at B9
Figure 4.6
From the result in Figure 4.6, of the fault generated at B9, we can clearly see
that all the branches failed when such fault occurs at B9, which is the incoming of
the 132KV supply before 35MVA transformer.
Output 3phase fault at B10
120
100
B9
B10
Magnitude
80
B11
60
B12
68%
B13
40
B14
B15
20
0
0
1
2
3
4
5
6
Fault resistance, Ohm
Figure 4.7
Output of 3phase fault at B10
53
From Figure 4.7, we can see for the fault generated at B10, or 11KV line
after the 35MVA transformer, the system will trip for fault resistance less than 2Ω.
Same result also repeated for fault at B11, B12, B14 and B15 at figure 4.8, 4.9 and
4.11.
Output of 3phase fault at B11
120
Magnitude, %
100
B9
B10
80
B11
60
B12
B13
40
B14
B15
20
0
0
1
2
3
4
5
6
resistance, Ohm
Output of 3-phase fault at B11
Figure 4.8
Output 3phase fault at B12
120
B9
100
Magnitude, %
B10
80
B11
B12
60
B13
B14
40
B15
20
0
0
2
4
6
Fault Resistance, Ohm
Figure 4.9
Output of 3phase fault at B12
54
Output of 3phase fault at B13
120
Magnitude, %
100
B9
B10
80
B11
B12
60
B13
40
B14
B15
20
0
0
1
2
3
4
5
6
Fault resistance, Ohm
Output of 3 phase fault at B13
Figure 4.10
Figure 4.10 shows on the lower impact on the network when the fault occurs
at B13, except when the fault resistance close ~ zero, where the magnitude less than
60%. This clearly seen that when fault is occurs at downstream, the impact of
voltage sag on the upstream is less.
Output of 3phase fault at B14
120
Magnitude, %
100
B9
B10
80
B11
B12
60
B13
40
B14
B15
20
0
0
1
2
3
4
5
6
Fault resistance, Ohm
Figure 4.11
Output of 3-phase fault at B14&B15
55
4.3
Mitigation
There are many mitigation for voltage sag available in the market as
mentioned in the chapter 2 earlier, but for the application proposed for the plant
under study is system with energy storage devices, the most suitable. This is due to
the type of load driven by the main motors are basically constant in power and the
changes is minimal. Sudden demand in reactive power is not the case of this plant
where normally Static VAR compensator or DSTATCOM used. The plant doesn’t
suffer flickering of voltage.
The only problem is; what type of energy storage should be used for such
application? Basically, solution that is with most economically viable and matured
system will be a preferred. Some of the guidelines for the selection of mitigation
are:
i.
The back-up system must be fast to switch to backup supply to avoid
interruption; the switch used should be very fast.
ii.
Energy storage should not be always on-line since this will shorten the
battery life (if battery used) due to charging and discharging
continuously. Basically this will reduce battery lifetime.
iii.
Good heat release to prolong battery life.
iv.
Cost effective and suitable for the application
v.
High reliability, high MTBF.
4.3.1 Proposal of mitigation
Figure 4.12 clearly shown how a backup supply installed in the mitigation,
and in the case above the energy storage system with DC source of supply injected
when interruption detected. The inverter will convert DC to AC, and filtered by an
LC filter. Battery converted to AC source by an IGBT Inverter, which will be
filtered with an LC filter with L=28mH and Qc = 100KVAr. Ideal switch is used to
switch between TNB supply and backup supply.
56
Backup supply injected during voltage sags for preheater fan A, as the
sample of the study.
Figure 4.12
Backup supply injected to system for Preheater fan B, during voltage
sag
Important requirement of the system also must be decided for the mitigation
proposal. And the energy storage will compensate the losing voltage based on the
setting value of the detection. This is clearly seen at figure 4.13 where the injected
supply to Preheater fan A or bus VabcB5, voltage source is able to maintain supply
to the motor. So, basically motor is protected from tripping of voltage sags.
57
Figure 4.13
VabcB5 line injected with back-up supply and compared to others
voltage sag without back up.
From the simulation, the backup supply injected is with the modulation index
~1.05;
And,
Vout = Vdc x 0.612 x 1.05 = 11KV
(6)
So,
Vdc = 17,170 V
Vdc 17,170V is the DC energy storage voltage required to completely
backup the operation of Preheater fan A as well B.
In this case 3MW load required, in normal installation, batteries will cost
~30-40% of the overall cost, so cost of installation will be as Table 4.2.
58
Comparison of price
Table 4.2
Price in
Lead
Nickel
Sodium
LTS*
LTS
GMF,
GMF,
acid
cadmium
sulphur SMES
SMES
high
low
battery
battery
battery
speed
speed
33,333
133,333
-
666,666
1,000,000
100,000
33,333
99,999
399,999
-
1,999,998
3,000,000
300,000
99,000
249,998
999,998
-
4,999,995
7,500,000
750,000
249,998
Pound for
1MW
Energy
storage
cost in
Pound,
40% of
total cost
Total
system
cost, Pound
Note: Price valid during the book printed (Source: Voltage quality in electrical power system, 1999,
IEE)
*LTS SMES – Low temperature Superconductor Magnetic Energy Storage
It can therefore be seen that at present the lead acid battery, low temperature
SMES and low-speed gyrating mass flywheel in particular are economically
significant. Batteries are particularly used for stand-by power supply application,
while gyrating mass flywheels and also SMES are worth considering as short term
storage devices to compensate for low frequency system perturbation.
4.4
Discussion of results
From Figure 4.6, we can see the plant will suffer most if the source of sag is
from the upstream or incoming supply. So, if the source of voltage sags is from
utilities or in Malaysia case, Tenaga National Berhad (TNB), the plant will suffer
voltage sags severely.
59
From figure 4.10, less impact is experienced by the equipments upstream if
the voltage sags source is from downstream or lower voltage level i.e.3.3KV. So, if
the source of voltage sags is from internal and the location is from e.g. 3.3KV, so
11KV lines will less affected by voltage sags. Basically voltage sags originating
from upstream will have bigger impact on the equipments downstream.
From the results of the analysis summarised in Figure 4.6 to 4.11, and from
the Power Quality analysis results, we can determine area of vulnerability to voltage
sags and focus on that area, mitigation will then proposed. Current voltage sags
magnitude, which only comply to SARFI 70 where any voltage sags below 68%
causing the plant to trip especially on Preheater fan A&B. We only focussing on
voltage sags fall above SARFI 30. SARFI below than 30 is not considered to reduce
total cost of investment. Furthermore, voltage sags for SARFI below than 30 is less
than 2 events per year, which is manageable.
Mitigation of the system proposed is by injecting a backup supply from
energy storage device to the equipments or lines we intended to protect. In the
project we use an ideal switch (or in actual application static switch used), to switch
between TNB supply and energy storage supply. We can see when voltage sag
detected, the static switch will divert the supply to energy storage device and after
the supply resume, and ideal switch will again switch back to TNB supply. Supply
successfully maintained during the period of voltage sags.
CHAPTER 5
CONCLUSIONS AND RECOMMENDATIONS FOR FUTURE WORKS
5.1
Conclusion
Voltage sags is the main power quality issues which causing a lot of losses to
cement manufacturing industries. Voltage sag detection with actual plant electrical
network line data modelling will help us to determine the location, magnitude and
period of voltage sag using simulation, which nodes are not conformance to SEMI
F47 or IEC standard.
But, from the analysis and all the data gathering, we discovered that, the
tripping of the preheater fan A and B, the most sensitive and important equipments
in the operation, not actually from the voltage sag reaching 68% since the voltage
sag profile of preheater fan A and B are quite similar with the other sag waveform.
Further inspection from the record doesn’t stated what protection actually
triggered for those 2 critical equipments, and the only relay that trip is master relay
for essential interlock, hence the control circuit that controlling the system for
Liquid Rheostat Starter drop off during voltage sag, particularly contactor.
Mitigation of the voltage sags also shows when the voltage sags occurs, the
backup supply recovered the missing voltage, where utilities line removed and
connected with backup supply.
61
5.2
Recommendations for future work
From the study, we discovered that the tripping on the preheater fan A and
Preheater fan B not actually due to tripping on protection relay on 11kV system, but
from the control system, and most probably the contactor. This statement supported
by the article written by IT de Villiers, “The behaviour of contactors during voltage
dips” giving his summary of his study as in the table 5.1 below:
Table 5.1
Comparison between pull-in and holding VA
Further study can be conducted to investigate the control system of the
Preheater fan A and Preheater fan B. Site test by connecting the source of control
supply (particularly 110V AC), with a programmable voltage source can be
arranged. The test will be done in stages with different timing and voltage. Result
will be compared to standard available. Figure 5.1 shows the schematic of the LV
sag generator test on equipments.
62
Figure 5.1
Schematic of control circuit test with sag generator to test the control
system
Example of the result and comparison to the standard can be view as sample
in Table 5.2.
Table 5.2
Sample result and comparison with standard reference
63
Figure 5.2 is the example of the solution to protect the control circuit.
Voltage sags proofing unit is installed in parallel with existing control system.
During normal operation supply to control system is from utilities and at the same
time charging the energy storage unit, and during voltage sags the energy storage
unit discharge the supply momentarily.
Figure 5.2
Control diagram of Preheater fan A&B and proposed mitigation to
protect control supply from voltage sags.
Further expansion of the equipments and electrical network with voltage
lower than 11KV is recommended, so the understanding of plant behaviours on
different voltage sags magnitude is fully understand.
64
REFERENCES
[1] Hamdan (2007), Report Study on Power Quality and Energy efficiency Unit,
TNB Energy Services.
[2] Y.Li, C.Mao (2006), Voltage Sag Study for a Practical Industrial Distribution
Network, IEEE, 2006 International Conference on Power Technology, P1-4.
[3] K.P Ross Ian (2006), Voltage Sags – An Explanation Causes, effect and
Correction, Omniverter Inc.
[4] E.Styvaktasis, Y.H.Gu, M.J.H Bollen (2001), Voltage Dip Detection and Power
System Transients, Sweeden, IEEE, P683-688.
[5] C.Radhakrishanan, M.Eshwardas, G.Chebiyam (2001) , Impact of Voltage Sags
in Practical Power System Networks, IEEE, P567-572.
[6] N.Kagan, E.L.Ferrari, N.M.Matsuo, S.X Duarte, J.L.Cavaretti, A.Tenorio,
L.R.Souza (2002), A Methodology for the Assessment of Short Duration Voltage
Variations in Electric Power Distribution System, IEEE, P577-581.
[7] IEEE Std 1159-1995 (1995), IEEE Recommendation Practice for Monitoring
Electric Power Quality, USA, IEEE Standards Board, 5-19.
[8] K.Ding, K.W.E.Cheng, X.D.Xue, B.P.Divakar, C.D.Xu, Y.B.Che, D.H.Wang
and P.Dong (2006), A Novel Detection Method for Voltage Sags, IEEE – 2006 2nd
International Conference on Power Electronics System and Applications, P250-288.
[9] J.A Oliver, R.Lawrence, B.B.Banerjee (2000), How to Specify Power Quality
Tolerant Process Equipment, IEEE, P281-289.
[10] T.Manmek, C.P.Mudannayake, C.Grantham (2006), Voltage Dip Detection
Based on Efficient Least Squares Algorithm for D-STATCOM Application, IEEE –
IPEMC 2006.
65
[11] Hadi Saadat, Power System Analysis, 2nd Edition, Milwaukee, USA, McGrawHill, 2004.
[12] H.Wayne Beaty, Handbook of Electrical Power Calculations, 3rd edition, USA,
McGraw-Hill, P9.2, 2001.
[13] J.Schlabbach, D. Blume, T.Stephanblome (2001), Voltage Quality in Electrical
System, London, UK, The Institution of Electrical Engineers, IEEE.
66
APPENDIX A
Characteristics for cables; resistances per km of positive sequence system at 20oC in
Ω/km
Conductor
mm
2
Resistance in Ω/km
Al
Cu
50
0.641
0.387
70
0.443
0.268
95
0.320
0.193
120
0.253
0.153
150
0.206
0.124
185
0.164
0.0991
240
0.125
0.0754
300
0.1
0.601
67
APPENDIX B
Characteristics for paper insulated cables; reactance per unit length of a positive
sequence system in Ω/km
Conductor
mm
2
Reactance in Ω/km
A
1KV
B
6KV
C
10KV 10KV 20KV 20KV
50
0.088 0.1
0.1
0.11
0.13
0.14
70
0.085 0.1
0.1
0.1
0.12
0.13
95
0.085 0.093 0.1
0.1
0.11
0.12
120
0.085 0.091 0.1
0.097
0.11
0.12
150
0.082 0.088 0.092
0.094
0.1
0.11
185
0.082 0.087 0.09
0.091
0.1
0.11
240
0.082 0.085 0.89
0.088
0.097
0.1
300
0.082 0.083 0.86
0.085
0.094
0.1
A) Cables with steel band armouring
B) Three core separately-sheathed cable
C) Single-core cables (triangular lying)
68
APPENDIX C
Characteristics for cables; reactance per km of a positive or sequence system in
Ω/km; using steel band armouring the reactance are increased by about 10%
Conductor
mm
2
Reactance in Ω/km
D
1KV
E
6KV
10KV 1KV
6KV
10KV
50
0.095 0.127 0.113
0.078
0.097
0.114
70
0.09
0.117 0.107
0.075
0.092
0.107
95
0.088 0.112 0.104
0.075
0.088
0.103
120
0.085 0.107 0.1
0.073
0.085
0.099
150
0.084 0.105 0.097
0.073
0.083
0.096
185
0.084 0.102 0.094
0.073
0.081
0.093
240
0.082 0.097 0.093
0.072
0.078
0.089
300
0.081 0.096 0.091
0.072
0.077
0.087
D) PVC multi-wire insulated cables
E) PV single-core cables (triangular lying)
69
APPENDIX D
Characteristics for cables; reactance per km of a positive sequence system in Ω/km;
using steel band armouring the reactance are increased by about 10%
Conductor
mm
2
Reactance in Ω/km
F
1KV
G
10KV 1KV
10KV
50
0.072 0.11
0.088 0.127
70
0.072 0.103
0.085 0.119
95
0.069 0.099
0.082 0.114
120
0.069 0.095
0.082 0.109
150
0.069 0.092
0.082 0.106
185
0.069 0.09
0.082 0.102
240
0.069 0.087
0.079 0.098
300
0.084
0.09
F)
XPET multi-wire insulated cable
G)
XPET single core insulated cables (triangular lying)
70
APPENDIX E
Cable calculation for the model
For example;
Cable to Mill House 1 is 2x570m PILC 185mm2x3cores so from Appendix 3
table, the resistance, r is 0.0991 Ω/km, hence
From (2);
R50 = R20 [1 + 0.00381(50-20)]
= 0.11 Ω/km
Cable reactance are given in the Appendix 4 and different type of cable are
with different reactance
So,
Inductance, XL = ωL = 2∏fL
Hence,
L = XL
2∏f
For example, for the same cable above;
XL = 0.091 Ω/km = 0.2897x10-3 H/km
2∏(50)
71
APPENDIX F
Characteristics of transformers
Ur
Sr (MVA)
Ukr (%)
URr (%)
MV/LV
0.05 – 0.63
4
1–2
0.63 – 2.5
6
1 – 1.5
MV/MV
2.5 – 25
6–9
0.7 – 1
HV/MV
25 - 63
10 – 16
0.6 – 0.8
Low voltage: Un < 1KV
Medium voltage: Un < 1KV- 66KV
High voltage: Un > 66KV
72
APPENDIX G
The Per Unit Conversion - Transformer
In order to comply with industry, we need specify the resistance and
inductance of the windings in per unit (p.u.).
The values are based on the
transformer rated power Pn, in VA, nominal frequency fn, in Hz, and nominal
voltage Vn, in Vrms, of the corresponding winding. For each winding, the per unit
resistance and inductance are defined as
Rp.u = R
and
Lp.u = L
Lbase
Rbase
The base resistance and base inductance used for each winding are
Rbase = (Vn)2
and
Pn
2∏fn
So, in the plant under study;
Voltage base, Vbase is 11KV
Transformer rated apparent power,
Pn = 10MVA
Hence;
From (10);
Rbase = (11x103/√3)2 = 4 Ω
10x106
and,
From (11);
Lbase = 4
2∏(50)
Lbase = Rbase
= 0.013H
73
So,
Rp.u = 0.028 = 0.007
4
Lp.u = 1.05x10-3 = 0.08
0.013
For the magnetization resistance Rm and inductance Lm, the p.u. values are based on
the transformer rated power and on the nominal voltage of winding 1.
To specify a magnetizing current of 0.2% (resistive and inductive) based on nominal
current, we enter per unit values of 1/0.002 = 500p.u. for the resistance and the
inductance of the magnetizing branch.
74
APPENDIX H
Result of Power Quality – voltage sag / swell for Incomer 1
Magnitude Magnitude Magnitude
No
Duration
Phase 1
Phase 2
Phase 3
Cause
1
0.06
84
95
96
SagSwell
3/24/200807:38:47.671 PM
2
0.059
97
84
84
SagSwell
3/15/200805:34:57.102 PM
3
0.05
95
96
85
SagSwell
2/6/200806:22:50.155 PM
4
1.18
61
81
83
SagSwell
2/4/200808:57:37.793 PM Trip
5
0.13
89
67
61
SagSwell
1/29/200804:59:02.145 PM
6
0.059
97
83
96
SagSwell
1/20/200812:59:56.098 AM
7
0.059
96
83
96
SagSwell
1/20/200812:59:48.747 AM
8
0.05
80
94
94
SagSwell
1/19/200807:15:10.472 PM
9
0.06
80
94
93
SagSwell
1/19/200807:15:04.272 PM
10
0.029
90
88
89
SagSwell
1/10/200804:58:49.424 PM
11
0.089
54
89
91
SagSwell
1/9/200803:44:42.919 PM Trip
12
0.059
75
74
91
SagSwell
1/9/200802:45:51.520 PM
13
0.07
93
79
93
SagSwell 12/27/200702:57:43.496 PM
14
0.07
80
93
93
SagSwell 12/27/200702:57:38.658 PM
15
0.07
92
79
93
SagSwell 12/27/200702:57:38.138 PM
16
0.189
91
4
93
SagSwell 12/24/200704:49:31.271 PM Trip
17
0.06
84
96
95
SagSwell 12/20/200703:20:06.921 PM
19
0.06
93
95
82
SagSwell 11/17/200701:23:23.513 PM
20
0.07
93
97
86
SagSwell 11/17/200701:23:21.239 PM
21
0.069
95
96
82
SagSwell
23
0.07
92
93
4
SagSwell 10/10/200703:56:49.580 AM Trip
24
0.08
91
89
36
SagSwell
9/29/200709:51:39.513 AM
25
0.069
74
95
95
SagSwell
9/23/200705:01:22.018 PM
26
0.89
93
92
82
SagSwell
8/23/200712:29:41.529 PM
28
0.692
87
95
97
SagSwell
8/5/200702:13:09.842 PM
29
0.07
82
92
93
SagSwell
7/30/200707:22:43.916 AM
30
0.06
93
84
95
SagSwell
7/29/200712:52:11.726 AM
31
0.41
87
96
96
SagSwell
7/21/200705:09:14.635 AM
32
0.07
90
89
89
SagSwell
7/15/200710:44:26.962 AM
33
0.03
96
95
89
SagSwell
6/28/200702:15:23.723 PM
34
0.089
93
92
84
SagSwell
6/28/200702:15:22.873 PM
35
4.995
125
125
125
SagSwell
6/18/200709:34:21.004 PM
36
0.99
95
76
95
SagSwell
6/10/200708:23:29.798 PM
Timestamp
Remarks
11/1/200702:52:13.193 AM
75
37
0.02
98
89
90
SagSwell
6/3/200710:28:27.900 AM
38
0.129
52
86
87
SagSwell
5/23/200702:50:09.211 PM
39
0.12
53
87
87
SagSwell
5/23/200702:50:05.384 PM
40
0.07
89
88
67
SagSwell
5/12/200702:22:15.708 PM
41
0.05
94
84
94
SagSwell
5/9/200708:05:54.836 AM
42
0.17
89
90
63
SagSwell
4/3/200704:34:04.751 PM
43
0.099
84
55
56
SagSwell
3/29/200704:25:46.310 PM
44
0.81
82
55
55
SagSwell
3/29/200704:25:43.779 PM
47
0.059
88
87
88
SagSwell
3/6/200703:01:16.973 PM
48
0.059
88
88
88
SagSwell
3/6/200702:55:23.222 PM
49
0.03
88
91
98
SagSwell
2/21/200704:16:25.362 PM
51
0.079
77
92
93
SagSwell
2/10/200710:06:17.644 AM
52
0.06
96
94
87
SagSwell
1/14/200707:33:48.662 PM
53
0.1
44
48
44
SagSwell
1/13/200704:35:09.454 PM Trip
54
0.05
82
93
93
SagSwell
1/8/200710:14:04.195 PM
55
0.059
82
95
95
SagSwell
12/3/200612:11:58.993 AM
56
0.049
95
93
88
SagSwell 11/25/200602:50:15.753 PM
57
0.039
95
96
86
SagSwell 11/24/200605:12:42.111 PM
58
0.01
95
89
96
SagSwell 11/19/200605:01:58.405 PM
59
0.04
93
82
94
SagSwell 11/17/200604:27:16.347 PM
60
0.05
83
93
93
SagSwell 11/17/200604:27:15.685 PM
61
0.06
80
91
91
SagSwell 11/17/200604:27:14.623 PM
62
0.03
96
96
89
SagSwell 11/15/200606:46:22.409 PM
63
0.069
86
95
96
SagSwell 11/11/200611:04:52.741 AM
64
0.039
97
89
97
SagSwell 10/30/200609:54:06.133 PM
65
0.04
88
87
98
SagSwell
10/8/200611:40:13.531 AM
66
0.089
66
89
90
SagSwell
9/11/200605:50:37.092 PM
67
0.14
53
53
52
SagSwell
8/12/200610:20:03.037 AM Trip
68
0.06
89
79
82
SagSwell
7/27/200604:18:09.689 PM
69
0.07
93
83
94
SagSwell
7/27/200604:18:05.872 PM
70
0.06
84
93
94
SagSwell
7/27/200604:18:05.572 PM
71
4.997
117
117
117
SagSwell
7/25/200607:45:46.005 AM
72
2.07
75
54
54
SagSwell
7/25/200607:45:38.402 AM Trip
73
0.05
87
96
96
SagSwell
7/22/200603:50:12.011 PM
74
0.069
74
95
95
SagSwell
7/21/200602:06:40.087 PM
75
0.07
67
91
91
SagSwell
7/5/200605:41:58.498 PM
76
0.029
95
88
93
SagSwell
6/29/200611:03:12.837 AM
77
0.059
94
84
91
SagSwell
6/29/200611:03:12.717 AM
78
0.029
88
96
97
SagSwell
5/27/200609:04:36.942 PM
76
79
0.079
91
93
69
SagSwell
5/24/200603:30:39.705 PM
80
0.339
84
84
84
SagSwell
5/20/200604:54:32.626 AM
81
0.089
66
68
67
SagSwell
5/17/200606:44:54.697 PM Trip
82
0.079
91
91
67
SagSwell
5/10/200604:14:31.677 PM
83
0.13
34
88
88
SagSwell
3/19/200611:07:39.092 AM
84
0.019
89
95
91
SagSwell
3/16/200605:17:55.240 PM
86
0.04
96
96
86
SagSwell
3/12/200605:09:58.964 PM
87
0.09
88
90
61
SagSwell
3/12/200605:09:58.144 PM
88
0.079
91
69
90
SagSwell
3/6/200606:47:54.102 PM
89
0.07
91
98
83
SagSwell
2/24/200603:53:34.940 PM
90
0.1
91
40
91
SagSwell
91
0.08
91
90
67
SagSwell
1/27/200601:44:28.121 AM
92
0.059
92
72
75
SagSwell
1/21/200610:25:26.956 AM
93
0.079
95
84
86
SagSwell
1/21/200610:25:26.696 AM
94
0.09
88
69
71
SagSwell
1/21/200610:25:21.690 AM
95
0.05
93
92
75
SagSwell 12/30/200503:47:44.844 PM
96
0.08
88
70
90
SagSwell 12/20/200512:41:54.500 PM
97
0.069
62
88
88
SagSwell 12/20/200503:16:39.408 AM
98
0.091
73
93
72
SagSwell 12/19/200510:29:50.871 AM
99
0.04
96
86
95
SagSwell 12/18/200502:37:14.093 AM
100 0.039
86
94
97
SagSwell 12/18/200502:37:13.683 AM
101 0.06
96
86
94
SagSwell 12/18/200502:37:13.444 AM
102 0.049
94
96
85
SagSwell 12/17/200502:37:13.254 AM
103 0.049
85
93
95
SagSwell 12/17/200509:29:14.742 AM
104 0.04
88
95
95
SagSwell 12/17/200509:29:14.532 AM
105 0.07
80
92
82
SagSwell 11/15/200509:29:13.671 AM
106 0.05
86
93
95
SagSwell 11/10/200501:24:04.459 PM
107 0.08
61
86
66
SagSwell 10/15/200504:54:48.771 PM
108 0.05
77
95
96
SagSwell 10/15/200506:33:29.427 PM
109 0.009
89
96
97
SagSwell
10/8/200505:15:07.302 PM
110 0.049
86
95
96
SagSwell
10/8/200504:56:21.778 PM
111 0.059
94
95
72
SagSwell
9/15/200502:34:13.086 PM
112 0.059
95
84
93
SagSwell
9/15/200502:30:31.372 PM
113 0.059
83
92
94
SagSwell
9/14/200502:30:31.062 PM
114 0.07
64
89
89
SagSwell
9/12/200509:18:21.157 AM
115 0.04
94
84
95
SagSwell
9/8/200502:46:42.855 PM
116 0.029
96
88
95
SagSwell
9/8/200510:20:38.195 AM
117 0.049
95
84
93
SagSwell
9/16/200510:20:38.075 AM
118 0.06
95
95
84
SagSwell
8/16/200503:23:34.302 PM
2/9/200609:56:12.349 AM Trip
77
120 5.008
191
190
191
SagSwell
8/4/200502:57:06.009 AM
121 3.235
2
3
0
SagSwell
8/4/200502:56:59.155 AM Trip
122 0.04
94
95
84
SagSwell
7/16/200505:35:44.776 PM
123 0.119
91
61
90
SagSwell
7/10/200506:37:09.320 AM
124 0.07
92
73
91
SagSwell
6/4/200508:44:59.730 AM
125 0.049
91
72
91
SagSwell
6/4/200508:44:58.859 AM
126 0.07
80
80
80
SagSwell
5/30/200506:13:46.315 PM
127 0.089
39
73
39
SagSwell
5/25/200507:06:35.462 PM Trip
128 0.1
77
43
44
SagSwell
5/25/200506:51:30.095 PM Trip
129 0.06
94
96
88
SagSwell
5/20/200512:50:40.896 PM
130 0.029
95
88
96
SagSwell
5/8/200512:18:20.046 AM
131 0.06
93
86
95
SagSwell
5/8/200512:18:19.196 AM
132 0.06
86
85
98
SagSwell
5/7/200503:17:57.998 PM
133 0.07
86
84
98
SagSwell
5/7/200503:17:52.065 PM
134 0.06
90
89
74
SagSwell
5/2/200504:18:10.490 PM
135 0.1
64
75
63
SagSwell
5/2/200504:18:10.390 PM Trip
136 0.381
88
59
60
SagSwell
4/27/200502:37:07.974 AM Trip
137 0.1
84
57
60
SagSwell
4/27/200502:37:07.203 AM Trip
138 0.09
90
91
55
SagSwell
4/27/200502:37:03.959 AM Trip
139 0.29
105
105
105
SagSwell
4/22/200506:12:46.294 PM
140 0.13
53
54
53
SagSwell
4/22/200506:12:45.723 PM Trip
141 0.08
34
88
88
SagSwell
4/20/200512:58:20.296 PM Trip
142 0.079
88
87
68
SagSwell
4/17/200505:09:26.279 PM Trip
143 0.059
82
79
98
SagSwell
4/17/200511:58:38.988 AM
144 0.53
79
91
93
SagSwell
4/16/200504:28:03.526 PM
145 0.31
73
88
91
SagSwell
4/16/200504:27:59.841 AM
146 0.049
84
94
94
SagSwell
3/24/200506:02:31.737 PM
147 0.06
93
93
80
SagSwell
3/14/200502:39:22.736 PM
148 0.1
90
90
70
SagSwell
3/14/200502:39:21.966 PM
149 0.059
94
86
95
SagSwell
3/3/200503:41:48.392 PM
150 0.07
96
84
96
SagSwell
2/17/200506:20:11.252 PM
151 0.059
96
84
96
SagSwell
2/17/200506:20:10.303 PM
152 0.039
88
96
97
SagSwell
2/17/200505:33:44.362 PM
153 0.05
96
96
89
SagSwell
2/17/200504:43:23.238 PM
154 0.059
84
86
93
SagSwell
2/17/200504:43:22.658 PM
155 0.039
93
92
79
SagSwell
2/17/200504:43:22.368 PM
156 0.05
78
91
91
SagSwell
2/17/200504:43:21.778 PM
157 3.57
110
110
110
SagSwell
1/13/200512:49:16.004 PM
158 5.712
121
121
121
SagSwell
1/13/200512:23:46.005 PM
78
159 0.177
59
59
59
SagSwell
1/13/200512:23:40.284 PM
160 0.108
112
111
112
SagSwell
1/13/200512:23:40.067 PM
161 0.206
49
45
50
SagSwell
1/13/200512:23:39.929 PM
162 0.098
110
109
110
SagSwell
1/13/200512:23:39.683 PM
163 0.268
45
43
44
SagSwell
1/13/200512:23:39.535 PM
164 0.109
107
107
108
SagSwell
1/13/200512:23:39.198 PM
165 0.927
65
64
64
SagSwell
1/13/200512:23:39.009 PM Trip
166 0.7
87
86
86
SagSwell
1/13/200512:23:34.619 PM
167 0.089
46
86
86
SagSwell
1/11/200507:07:20.596 PM
168 0.02
90
89
90
SagSwell 12/30/200405:00:00.644 PM
169 0.07
90
94
77
SagSwell 12/19/200408:17:11.128 PM
170 0.06
95
96
87
SagSwell 12/19/200408:17:08.948 PM
171 0.059
88
92
73
SagSwell 12/19/200408:17:07.968 PM
172 0.03
95
95
89
SagSwell 12/14/200404:14:14.191 PM
173 0.029
95
95
89
SagSwell 12/14/200404:14:02.784 PM
174 0.05
78
92
91
SagSwell
12/9/200405:20:10.695 PM
175 0.059
78
92
92
SagSwell
12/5/200408:43:48.769 PM
176 0.01
89
97
95
SagSwell 11/28/200401:15:24.644 PM
177 0.049
95
89
94
SagSwell 11/24/200410:24:07.549 AM
178 0.38
88
89
63
SagSwell 11/12/200411:30:03.872 AM Trip
179 4.997
106
106
106
SagSwell 11/11/200411:46:41.004 PM
180 1.787
68
69
93
SagSwell 11/11/200411:46:32.617 PM
181 0.239
55
55
70
SagSwell 11/11/200411:46:28.883 PM Trip
182 0.04
88
96
95
SagSwell 11/11/200405:41:49.760 PM
183 0.07
83
94
95
SagSwell 11/10/200411:31:57.778 PM
184 0.069
96
85
95
SagSwell 11/10/200411:23:42.488 PM
185 0.11
91
82
83
SagSwell
186 0.05
96
87
96
SagSwell 10/31/200406:54:34.117 PM
187 0.049
87
95
94
SagSwell 10/30/200401:31:20.893 PM
188 0.03
89
96
95
SagSwell 10/30/200401:31:20.243 PM
189 0.08
84
92
91
SagSwell 10/30/200401:31:17.071 PM
190 0.06
86
87
96
SagSwell 10/23/200408:22:10.048 PM
191 0.06
72
73
72
SagSwell 10/14/200401:26:02.215 AM
11/6/200405:44:55.066 PM
79
APPENDIX I
Result of Power Quality – voltage sag/swell for Incomer 2
Magnitude Magnitude Magnitude
No
Duration
Phase 1
Phase 2
Phase 3
Cause
Timestamp
Remarks
1
0.059
84
96
96
SagSwell
3/24/200807:38:48.511 PM
2
0.059
97
84
84
SagSwell
3/15/200805:34:57.589 PM
3
0.049
95
96
85
SagSwell
2/6/200806:22:49.958 PM
4
1.18
61
81
83
SagSwell
2/4/200808:57:38.238 AM Trip
5
0.129
88
67
61
SagSwell
1/29/200804:59:01.692 PM
6
0.06
97
83
96
SagSwell
1/20/200812:59:55.623 AM
7
0.059
96
83
96
SagSwell
1/20/200812:59:48.273 AM
8
0.05
80
94
94
SagSwell
1/19/200807:15:10.187 PM
9
0.06
80
94
93
SagSwell
1/19/200807:15:03.987 PM
10
0.03
90
88
89
SagSwell
1/10/200804:58:49.472 PM
11
0.09
54
89
91
SagSwell
1/9/200803:44:43.751 PM Trip
12
0.06
75
74
91
SagSwell
1/9/200802:45:51.363 PM
13
0.071
93
80
93
SagSwell 12/27/200702:57:43.681 PM
14
0.069
80
93
93
SagSwell 12/27/200702:57:38.843 PM
15
0.069
92
79
93
SagSwell 12/27/200702:57:38.323 PM
16
0.189
90
4
93
SagSwell 12/24/200704:49:31.574 PM Trip
17
0.06
84
96
95
SagSwell 12/20/200703:20:07.014 PM
20
0.06
93
95
82
SagSwell 11/17/200701:23:23.530 PM
21
0.07
93
97
86
SagSwell 11/17/200701:23:21.256 PM
22
0.069
95
96
82
SagSwell
23
0.11
98
84
84
SagSwell 10/28/200704:33:50.074 AM
24
0.08
97
70
67
SagSwell 10/28/200704:33:49.394 PM
25
0.12
95
67
61
SagSwell 10/28/200704:33:46.233 PM Trip
26
0.07
92
93
4
SagSwell 10/10/200703:56:49.379 AM Trip
27
0.079
90
89
36
SagSwell
9/29/200709:51:39.337 AM
28
0.069
74
95
95
SagSwell
9/23/200705:01:21.877 PM
29
0.09
93
92
82
SagSwell
8/23/200712:29:42.088 PM
31
0.692
87
95
97
SagSwell
8/5/200702:13:10.242 PM
32
0.07
82
92
93
SagSwell
7/30/200707:22:43.351 AM
33
0.06
93
84
95
SagSwell
7/29/200712:52:12.119 AM
34
0.04
87
96
96
SagSwell
7/21/200705:09:14.614 AM
35
0.07
90
89
89
SagSwell
7/15/200710:44:26.194 AM
11/1/200702:52:13.131 AM
80
37
0.1
95
76
95
SagSwell
6/10/200708:23:30.042 PM
38
0.02
98
89
90
SagSwell
6/3/200710:28:27.628 AM
39
0.129
53
87
88
SagSwell
5/23/200702:50:08.744 PM
40
0.12
53
87
87
SagSwell
5/23/200702:50:04.880 PM
41
0.07
89
88
67
SagSwell
5/12/200702:22:15.548 PM
42
0.049
94
84
94
SagSwell
5/9/200708:05:54.090 AM
43
0.17
89
90
63
SagSwell
4/3/200704:34:03.834 PM
45
0.059
88
88
88
SagSwell
3/6/200703:01:16.974 PM
46
0.059
88
88
88
SagSwell
3/6/200702:55:23.226 PM
48
0.079
77
92
93
SagSwell
2/10/200710:06:17.696 AM
49
0.059
96
94
87
SagSwell
1/14/200707:33:48.511 PM
50
0.099
44
48
44
SagSwell
1/13/200704:35:10.092 PM Trip
51
0.05
82
93
94
SagSwell
1/8/200710:14:04.508 PM
52
0.061
82
95
95
SagSwell
12/3/200612:11:59.669 AM
53
0.049
95
93
88
SagSwell 11/25/200602:50:15.646 PM
54
0.039
95
96
86
SagSwell 11/24/200605:12:26.211 PM
55
0.01
95
89
96
SagSwell 11/19/200605:01:46.183 PM
56
0.039
93
82
93
SagSwell 11/17/200604:27:05.695 PM
57
0.05
83
93
93
SagSwell 11/17/200604:27:05.033 PM
58
0.06
80
91
91
SagSwell 11/17/200602:27:03.971 PM
59
0.031
96
96
89
SagSwell 11/15/200606:46:13.16676
PM
60
0.07
86
95
96
SagSwell 11/11/200611:04:46.845 AM
61
0.039
97
89
97
SagSwell 10/30/200609:54:05.978 PM
62
0.039
88
87
98
SagSwell
10/8/200611:40:13.550 AM
63
0.09
66
89
90
SagSwell
9/11/200605:50:37.760 PM
64
0.14
53
53
53
SagSwell
8/12/200610:20:03.838 AM Trip
65
0.06
89
79
82
SagSwell
7/27/200604:18:09.179 PM
66
0.07
92
83
94
SagSwell
7/27/200604:18:05.363 PM
67
0.059
84
93
94
SagSwell
7/27/200604:18:05.062 PM
68
5.006
117
117
117
SagSwell
7/25/200607:45:46.009 AM
69
2.069
75
54
54
SagSwell
7/25/200607:45:38.675 AM Trip
70
0.051
87
96
96
SagSwell
7/22/200603:50:12.335 PM
71
0.069
74
95
95
SagSwell
7/21/200602:06:40.192 PM
72
0.07
66
91
91
SagSwell
7/5/200605:41:59.235 PM
73
0.029
95
88
94
SagSwell
6/29/200611:03:13.110 AM
74
0.059
94
84
91
SagSwell
6/29/200611:03:12.990 AM
75
0.029
88
96
97
SagSwell
5/27/200609:04:36.990 PM
76
0.08
91
93
69
SagSwell
5/24/200603:30:37.460 PM
77
0.34
84
84
84
SagSwell
5/20/200604:54:32.736 AM
81
78
0.09
66
68
67
SagSwell
5/17/200606:44:54.586 PM Trip
79
0.079
91
91
67
SagSwell
5/10/200604:14:31.953 PM
80
0.131
34
88
88
SagSwell
3/19/200611:07:38.585 AM
82
0.041
96
96
86
SagSwell
3/12/200605:09:59.296 PM
83
0.09
88
90
61
SagSwell
3/12/200605:09:58.475 PM
84
0.079
91
69
90
SagSwell
3/6/200606:47:53.886 PM
85
0.07
91
98
83
SagSwell
2/24/200603:53:34.170 PM
86
0.099
91
40
91
SagSwell
87
0.08
91
90
67
SagSwell
1/27/200601:44:28.674 AM
88
0.059
92
72
75
SagSwell
1/21/200610:25:26.777 AM
89
0.079
95
84
86
SagSwell
1/21/200610:25:26.518 AM
90
0.09
88
69
71
SagSwell
1/21/200610:25:21.511 AM
91
0.049
93
93
76
SagSwell 12/30/200603:47:44.634 PM
92
0.08
88
70
90
SagSwell 12/20/200512:41:54.924 PM
93
0.069
62
88
88
SagSwell 12/20/200503:16:39.133 AM
94
0.09
73
93
72
SagSwell 12/19/200510:29:51.146 AM
95
0.039
96
86
95
SagSwell 12/18/200502:37:14.306 AM
96
0.05
86
94
97
SagSwell 12/18/200502:37:13.907 AM
97
0.059
96
86
95
SagSwell 12/18/200502:37:13.657 AM
98
0.049
94
96
86
SagSwell 12/18/200502:37:13.467 AM
99
0.05
85
93
95
SagSwell 12/17/200509:29:14.455 AM
100 0.04
88
95
95
SagSwell 12/17/200509:29:14.245 AM
101 0.071
80
92
92
SagSwell 12/17/200509:29:13.384 AM
102 0.049
86
93
95
SagSwell 11/15/200501:24:04.200 PM
103 0.079
61
86
66
SagSwell 11/10/200504:54:49.082 PM
104 0.05
77
95
96
SagSwell 10/15/200506:33:29.011 PM
105 0.029
89
96
97
SagSwell 10/15/200505:15:06.929 PM
106 0.049
86
95
96
SagSwell
10/8/200504:56:21.797 PM
107 0.059
94
95
72
SagSwell
10/8/200502:34:13.183 PM
108 0.059
95
84
93
SagSwell
9/15/200502:30:16.122 PM
109 0.059
83
92
94
SagSwell
9/15/200502:30:15.812 PM
110 0.07
64
89
89
SagSwell
9/14/200509:18:06.851 AM
111 0.039
94
84
95
SagSwell
9/12/200502:46:29.843 PM
112 0.03
96
88
95
SagSwell
9/8/200510:20:28.315 AM
113 0.05
95
84
93
SagSwell
9/8/200510:20:28.196 AM
114 0.06
95
95
84
SagSwell
8/16/200503:23:34.145 PM
115 0.16
88
93
11
SagSwell
116 0.04
94
95
84
SagSwell
7/16/200505:35:43.791 PM
117 0.119
91
61
90
SagSwell
7/10/200506:37:09.217 AM
2/9/200609:56:11.906 AM Trip
8/4/200502:56:55.204 AM Trip
82
118 0.07
92
73
91
SagSwell
6/4/200508:44:59.337 AM
119 0.049
91
72
91
SagSwell
6/4/200508:44:58.467 AM
120 0.069
80
80
80
SagSwell
5/30/200506:13:46.306 PM
121 0.089
39
73
39
SagSwell
5/25/200507:06:35.166 PM Trip
122 0.1
77
43
44
SagSwell
5/25/200506:51:29.808 PM Trip
123 0.059
94
96
88
SagSwell
5/20/200512:50:41.346 PM
124 0.03
95
88
96
SagSwell
5/8/200512:18:19.815 AM
125 0.06
93
86
95
SagSwell
5/8/200512:18:18.966 AM
126 0.06
86
85
98
SagSwell
5/7/200503:17:58.031 PM
127 0.07
86
84
98
SagSwell
5/7/200503:17:52.098 PM
128 0.06
90
89
74
SagSwell
5/2/200504:18:10.104 PM
129 0.1
64
75
63
SagSwell
5/2/200504:18:10.004 PM Trip
130 0.381
88
59
60
SagSwell
4/27/200502:37:08.651 AM
131 0.1
84
57
60
SagSwell
4/27/200502:37:07.880 AM Trip
132 0.09
90
91
55
SagSwell
4/27/200502:37:04.636 AM
133 0.009
104
105
105
SagSwell
4/22/200506:12:46.040 PM
134 0.03
104
105
105
SagSwell
4/22/200506:12:45.999 PM
135 0.13
53
54
53
SagSwell
4/22/200506:12:45.659 PM Trip
136 0.08
34
88
88
SagSwell
4/20/200512:58:19.783 PM Trip
137 0.079
88
87
68
SagSwell
4/17/200505:09:25.817 PM Trip
138 0.06
82
79
98
SagSwell
4/17/200511:58:38.684 AM
139 0.531
79
91
94
SagSwell
4/16/200504:28:03.837 PM
140 0.31
73
88
91
SagSwell
4/16/200504:28:00.153 PM
141 0.049
84
94
94
SagSwell
3/24/200508:02:31.667 PM
142 0.06
93
93
80
SagSwell
3/14/200502:39:23.049 PM
143 0.1
90
90
70
SagSwell
3/14/200502:39:22.279 PM
144 0.059
94
86
95
SagSwell
3/3/200503:41:47.663 PM
145 0.07
96
84
96
SagSwell
2/17/200506:20:10.819 PM
146 0.059
96
84
96
SagSwell
2/17/200506:20:09.870 PM
147 0.039
88
96
97
SagSwell
2/17/200505:33:43.954 PM
148 0.05
96
96
89
SagSwell
2/17/200504:43:22.858 PM
149 0.059
84
86
93
SagSwell
2/17/200504:43:22.278 PM
150 0.04
93
92
79
SagSwell
2/17/200504:43:21.988 PM
151 0.05
78
91
91
SagSwell
2/17/200504:43:21.398 PM
152 6.44
118
118
118
SagSwell
1/13/200512:23:46.001 PM
153 0.168
60
59
59
SagSwell
1/13/200512:23:39.541 PM
154 0.118
113
113
113
SagSwell
1/13/200512:23:39.344 PM
155 0.197
50
46
51
SagSwell
1/13/200512:23:39.186 PM
156 0.108
112
111
111
SagSwell
1/13/200512:23:38.948 PM
83
157 0.266
45
44
45
SagSwell
1/13/200512:23:38.800 PM
158 0.129
109
108
109
SagSwell
1/13/200512:23:38.474 PM
159 0.019
89
89
90
SagSwell
1/13/200512:23:38.265 PM
160 0.857
66
64
65
SagSwell
1/13/200512:23:38.235 PM Trip
161 0.7
87
86
86
SagSwell
1/13/200512:23:33.885 PM
162 0.089
46
86
86
SagSwell
1/11/200507:07:19.066 PM
163 0.02
90
89
90
SagSwell 12/30/200404:59:58.865 PM
164 0.071
89
94
77
SagSwell 12/19/200408:17:09.525 PM
165 0.06
95
96
87
SagSwell 12/19/200408:17:07.345 PM
166 0.059
88
92
73
SagSwell 12/19/200408:17:06.364 PM
167 0.03
95
95
89
SagSwell 12/14/200404:14:13.443 PM
168 0.029
95
95
89
SagSwell 12/14/200404:14:02.037 PM
169 0.05
78
92
91
SagSwell
12/9/200405:20:09.561 PM
170 0.06
78
92
92
SagSwell
12/5/200408:43:47.493 PM
171 0.01
89
96
95
SagSwell 11/28/200401:15:23.771 PM
172 0.049
95
89
94
SagSwell 11/24/200410:24:06.743 AM
173 0.38
88
89
63
SagSwell 11/12/200411:36:03.007 AM Trip
174 4.997
106
106
106
SagSwell 11/11/200411:46:41.003 PM
175 1.787
68
69
93
SagSwell 11/11/200411:46:32.107 PM
176 0.24
56
55
70
SagSwell 11/11/200411:46:28.373 PM Trip
177 0.039
88
96
95
SagSwell 11/11/200405:41:49.453 PM
178 0.07
83
94
95
SagSwell 11/10/200411:31:57.005 PM
179 0.069
96
85
95
SagSwell 11/10/200411:23:41.719 PM
180 0.11
91
82
83
SagSwell
181 0.05
96
88
96
SagSwell 10/31/200406:54:32.492 PM
182 0.049
87
95
94
SagSwell 10/30/200401:31:20.177 PM
183 0.031
89
96
95
SagSwell 10/30/200401:31:19.526 PM
184 0.08
84
92
91
SagSwell 10/30/200401:31:16.354 PM
185 0.06
86
87
96
SagSwell 10/23/200408:22:05.796 PM
186 0.06
72
73
72
SagSwell 10/14/200401:26:00.931 AM
11/6/200405:44:54.408 PM
84
APPENDIX J
Magnitude of the voltage when applied 3-phase fault on different location
Fault
location
Sag
B9
B10
B11
B12
B9 B10 B11 B12 B13 B14 B15
0
0
0
0
0
0
0
0
1
8
7
7
7
6
7
7
2
13
15
15
15
11
12
12
3
13
19
19
19
17
14
14
4
25
26
22
22
23
24
24
5
33
30
30
30
28
29
29
B9 B10 B11 B12 B13 B14 B15
0 100
0
0
0
0
0
0
1 100
44
44
44
47
45
45
2 100
67
67
67
66
67
67
3 100
81
81
81
77
76
76
4 100
85
85
85
85
86
86
5 100
89
89
89
85
86
86
B9 B10 B11 B12 B13 B14 B15
0 100
0
0
0
0
0
0
1 100
45
45
45
45
46
46
2 100
68
68
68
65
69
69
3 100
82
82
77
75
80
80
4 100
86
86
86
85
83
83
5 100
91
91
91
88
86
86
B9 B10 B11 B12 B13 B14 B15
0 100
0
0
0
0
0
0
1 100
44
44
44
89
48
48
2 100
70
70
70
68
69
69
3 100
81
81
81
81
81
81
4 100
81
81
81
87
86
86
5 100
89
89
89
89
90
90
85
B13
B9 B10 B11 B12 B13 B14 B15
0 100
52
52
52
0
55
55
1 100 100 100 100 100 100 100
2 100 100 100 100 100 100 100
3 100 100 100 100 100 100 100
4 100 100 100 100 100 100 100
5 100
B14
B15
52
52
52
0
55
55
B9 B10 B11 B12 B13 B14 B15
0 100
9
9
9
5
0
6
1 100
44
44
44
47
43
43
2 100
74
74
74
68
67
67
3 100
81
81
81
79
76
76
4 100
89
89
89
85
86
86
5 100
89
89
89
89
86
86
B9 B10 B11 B12 B13 B14 B15
0 100
7
7
7
4
0
5
1 100
44
44
44
47
43
43
2 100
74
74
74
68
67
67
3 100
81
81
81
79
76
76
4 100
89
89
89
85
86
86
5 100
89
89
89
89
86
86