Appendices

Appendix – I
Details of Chandrapur Padghe HVDC Link
The Power demand in the State of Maharashtra is concentrated in the western part of
the State around Mumbai, Pune, Nashik regions whereas the major thermal power generation
is concentrated in the eastern part of the state due to abundance of coal stock in that area.
The installed capacity of Chandrapur Thermal Power Station is 2340 MW. MahaGENCO
share of 577 from NTPC’s Korba Super Thermal Power Station is also received at
Chandrapur over 440 kV double circuit Bhilai Chandrapur line of Power Grid Corporation
India Ltd. (PGCIL). The Total Power is to be evacuated from Chandrapur 400 kV bus is
around 2700 MW. The existing transmission network comprising of three 400 kV circuits
between Chanrdapur and Mumbai can safely transmit around 1200 MW of power without
considering any contingency outages. It was therefore necessary to provide additional
transmission capacity of around 1500 MW between Chandrapur and Mumbai. Expansion of
400 kV transmission network by constructing several 400 kV lines was not feasible due to
severe constraints of right of way. Therefore the other two options viz. Construction of 800
kV AC link or, HVDC bipole link was considered. The option of HVDC bipole link was
found to be a better option considering long term requirement.

System Description
The Chandrapur – Padghe HVDC Bipole link has two poles one positive and the other
negative. The DC voltage of each pole is 500 kV. The salient details of the link are as given
below.
Nominal Continuous Power Flow rating : 1500 MW (From Chandrapur to Padghe)
Overload Capability : 1650 MW for two hours
2000 MW for five second
Low Ambient Raring : 1650 MW continuous
0
(Temp. below 33 C) : 2200 MW for five second
Minimum power flow at monopolar : 75 MW for five second
operation
Acceptable AC voltage Variation : Between 380 kV to 430 kV at Chandrapur

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 : Between 360 kV to 420 kV at Padghe
Acceptable Frequency variation : Between 47.5 Hz and 51.5 Hz

Operational modes

The DC link can be operated in a number of operational modes described below.

Some operational modes can be utilized jointly.
• Balaced Bipoler Mode: In this mode the unbalance current flowing through the
ground is controlled to maximum 10 A.
• Monopolar Mode with ground return: In this mode the electrode lines together
with ground with ground electrode of each station are utilized as return path.
• Monopolar mode with metallic return: In this mode the line conductor of the
unused pole is utilized as return path with one ground electrode (Chandrapur end)
insolated.
• Reduced DC Voltage: The link can be operated at 400 kV DC up to 1000 MW
power during deteriorated insulation conditions of the line. This can do for each pole
individually with power rating of 500 MW per pole.
• Reverse Power Operation: The normal power flow is from Chandrapur to Padghe.
The link can also transmit upto 1466 MW in the opposite direction.

Thyristor valves
The Thyristor valves form the heart of HCDC system.

Type of Thyristor Valves : 3 nos. Quadruple per pole

Weight of each quadruple valve : 30 Tones
Installation : Indoor suspended in valve halls (26 m High)
Cooling : Water cooled with closed loop single cooling system
Connection of thyristor in valve : Series
High potential end of valve : Towards ceiling

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Thyristor in single valve : 96 nos.
Thyristor in quadruple valve : 384 nos.
Thyristor per pole : 1152 nos.
Thyristor in a section : 2304 nos.
Area of each thyristor : 45 sq.cm.
Max Voltage of thyristor : 7 kV
Rated current of thyristor : 1700 Amp DC
Pulse group : 12 pulse per pole

Valve cooling system

The valve cooling equipment consists of a fine water circuit. The water circulated by means
of pump in the circuit. The water is heated in the thyristor valves by the valve losses. The
heated water is then cooled in air cooked liquid coolers.
Fine water cooling circuit
The fine cooling circuit consists if a main cooling circuit and a treatment circuit.
Main cooling circuit
The main cooling circuit consists of water with the thyristor valves in a desecration vessel,
pumps and filters. One of the two fine water pumps circulates the water through the main
cooling circuit and water treatment circuit. The pump is included for redundancy purpose.
Water treatment circuit
Approximately 3% of the main flow is circulated in the water treatment circuit. The water
treatment circuit consists of empty deoxygenizer two ion exchangers, one mechanical filter
and expansion vessel with solenoid valve. Nitrogen bubbling system is provided for removal
of oxygen dissolved in water. The water treatment circuit is provided with a makeup pump
and associated valves.
Air cooled liquid coolers
Air Cooled liquid coolers cool the heated water from the thyristor valves
Converter transformer
The converter transformers are provided to connect to the 400kV station with HVDC
converter by transforming the voltage to such a value that the voltage of each pole of DC line
becomes 500 kV.

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Number of transformers in each terminal 6 Nos, Single phases 3 winding. + one
spare unit
Secondary winding connection 1 Star
1 delta
Nominal Voltage
Line winding 400 3 kV
Valve winding
Star 211 3 kV
Delta 211 kV
Rated power of each unit 298.6 MVA

Line winding onload tap changer

Range + 18% to – 10%
No. of Steps 28
Step size 1.25%
Total weight of each unit 359 Tonnes

Smoothing reactors
Type of reactors iron core oil insulted
No. of reactors One per pole with one spare unit at each station.
Rating 566 kV DC , 360 mH, 1700 Amp DC

AC filter
No. of Filters per station
HP 12 single tuned 4 nos.
HP 24/36 double tuned 2 nos.
HP 3 3 nos.
Nos. of filter banks per station 4 nos.
Rating of each filter bank 200 MVA

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DC filter
Double tuned branches per pole 1 no. – 2/6th harmonic
1 no. – 12/24th harmonic
Rating of Second harmonic filter branch 2 micro farad at 650 kV DC

HVDC line
Length of the line 753 km
Number of poles Two
Nominal DC Voltage +/-500 kV
Highest DC Voltage +/-512 kV
Number of earth wires two (One AAAC and one OPGW)
Total number of towers 1970
Total tonnage of towers 25100 MT (Approx)
Maximum height of tower 63.23 meter from ground level (A+24)
Total length of Bersimis conductor used 6026 km
Total length of 80 sq. mm AAAC used 760 km
Total length of 24 fiber OPGW used 760 km
DC insulator (Porcelain and toughened glass) 502350 nos.

HVDC electrode station and electrode line

There are two electrode stations, one located at Chincholi which is about 22 km from
Chandrapur terminal and the other located at Anjur which is about 23 km from Padghe
terminal. These electrode stations are connected to terminal station through overhead lines of
33 kV rating.

Optical communication
In order to ensure reliable communication between two terminals for transfer of control,
protection, information data an optical communication system utilizing OPGW on the DC
line is provided as main with a PLCC system as back up. Optical fiber system with 24 fiber is
being provided in the country for the first time over such a long distance. There are 5 Nos. of

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repeater stations and 2 number of interface stations along the HVDC line located at the
various places as under:
Repeater station: Dhaba, Malkini Ahengaon, Hatwan and Hiwara.
Interface station: Dahegaon and Guha

Special features
• Reactive power control: By switching in and out filter banks either the reactive power
exchange or the AC voltage line be kept at targeted levels with dead bands which can be
set by the operator.
• Damping control: In case of AC lines or generator tripping, the parallel AC system
might start oscillating. The damping controller will counteract these power swings thus
giving the AC system a higher stability limit.
• Frequency control system: The fully computerized control and protection system has
been duplicated with one active system and one hot standby system. This will ensure high
reliability and availability of the HVDC System.
• Active DC filler: Active DC filter has been provided for the first time for an overhead
line transmission. The principle of an active filter is to inject in the DC line a controlled
current consisting of the harmonic currents not eliminated by the passive filters, but with
each component in phase opposition, so that a cancellation of harmonic currents occurs
thus eliminating harmonics on DC side.
• Transfer between metallic and ground return: Special equipments are included so that
the transfer can be made without interruption in the power flow.
• Various master control locations: The master control can be selected to be Padghe or
Chandrapur. In Chandrapur and Padghe station the control can be operated from SCADA,
mimic or backup mimic selected control signals can be issued from Kalwa (load dispatch
centre) also.
• Line fault locator: A special line fault locator has been developed for this project with a
resolution of 1km.
• Electrode line supervision: By an active supervision of the electrode line it is possible to
detect even high impedance faults.

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• Diesel generation sets: At each terminal station two diesel generation sets are provided,
each giving 100% standby capacity, since each DG set is rated to meet entire essential
load of the station.
• Uninterrupted power supply (UPS): This arrangement has been provided for feeding
the valve cooling pumps with 15 mins capacity in order to have an uninterrupted power
flow even if both DG sets fail.
• Fire fighting system: Similar to other installations, mulsifire system along with sprinkler
system for valves, AFFF system for oil insulated bushings, high velocity water spray
system for transformers and smoothing reactors, CO2 system for station control room and
pole control room, hydrant system for switchyard and portable fire extinguishers from the
complete fire protection system. In addition addressable type of fire detection system and
VESDA system for valve hall are the unique features of fire protection system. The CO2
protection system provided for control room and other installation in the service building
are unique for MSEB.

HVDC SCADA
For effective monitoring of total HVDC system, Supervisory Control and Data
Acquisition (SCADA) system has been provided. The system is integrated with the control
equipment in HVDC converter stations. For communication between two converter station
and State Load Dispatch (LD) station Kalwa. OPGW provided on HVDC line and 200 kV
Padghe Kalwa line is used.
SCADA equipment provided at Padghe Chandrapur and L.D. station Kalwa display
the key parameters like power flow, current position of breakers earth switches etc. HVDC
system logs the entire event / alarm of self as well as remote (other) station. Control function
like modifying power order or rate of ramping can be set either through SCADA system or
Mimic panel provided.

The Unique Feature

In addition inspection windows provided in the station control room for visual inspection of
valves a special potential free cage is also provided inside each valve hall for visual

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inspection of valves during energized condition. This is the first ever HVDC project in the
world where such type of provision for inspection of valves is available.

Executing Agencies
The work of terminal station as well as repeater and interface station including design
manufacturing, supply, complete erection, testing and commissioning has been executed by
M/s Bharat Heavy Electrical Ltd. (BHEL) M/s ABB power system AB, Sweden and
M/s ABB India Ltd. Mumbai. The erection of HVDC line is done by M/s Jyoti Structures,
M/s Best & Crompton, M/s KEC International and M/s Kalpataru Power Transmission. The
design of electrode stations bas been done by MSEB with the help of Hydro Quebec
International (HQI) and SNC Lavalin, Canada. The erection of electrode lines has been
carried out by M/s Transral Baroda. The electrode stations are constructed by MSEB
departmentally. NTPC India HQI Canada and SNC Lavalin Canada provided consultancy
for preparation of technical specifications for terminals and line. The OPGW & OFAC and
its accessories required for optical communication system are supplied by M/s BICO UK and
splicing is done by M/s OPTEL Telecommunication Ltd. Bhopal and M/s Kalindee Rail
Niram Ltd. Jaipur. The porcelain insulator for the line are supplied by M/s NGK insulator,
Japan through M/s Mitsui Japan. The toughened glass insulators are supplied by M/s Sedever
France.

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187
Photograph: 500 kV DC Terminal Tower

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Photograph: 500 kV DC Terminal Tower

Photograph: Close View of Tower Top

Photograph: Close View of Tower Top

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 Photograph: Switch Yard

Converter Transformer at HVDC Station, Chandrapur

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400 kV A.C. Switchyard in HVDC Terminal Station Chandrapur

33 kV Neutral Connections, DC Breaker and DCCT

298.6 MVA Single Phase Converter Transformer

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Lightening Arrester (500 kV) and Smoothing Reactor

AC Filter Area

500 kV DC Yard at Chandrapur

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 Appendix - II
Program for Filter Performance Analysis
clear
close all
I3=input('Enter the magnitude of 3rd harmonic current= ')
I13=input('Enter the magnitude of 13th harmonic current= ')
I15=input('Enter the magnitude of 15th harmonic current= ')
I25=input('Enter the magnitude of 25rd harmonic current= ')
I37=input('Enter the magnitude of 37th harmonic current= ')
E1=231*1000;
Z3=3000;
Z13=650;
Z15=5000;
Z25=1065;
Z37=1065;
NumD3=I3*Z3*100;
D3=NumD3/E1;
NumD13=I13*Z13*100;
D13=NumD13/E1;
NumD15=I15*Z15*100;
D15=NumD15/E1;
NumD25=I25*Z25*100;
D25=NumD25/E1;
NumD37=I37*Z37*100;
D37=NumD37/E1;
NumDtotal=(I3*Z3+I13*Z13+I15*Z15+I25*Z25+I37*Z37)*100;
Dtotal=NumDtotal/E1;

disp('D3 = '); disp(D3);

disp('D13 = '); disp(D13);
disp('D15 = '); disp(D15);

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disp('D25 = '); disp(D25);
disp('D37 = '); disp(D37);
disp('Dtotal = '); disp(Dtotal);

if(D3<=1 & D13<=1 & D15<=1 & D25<=1 & D37<=1 & Dtotal<=4)
sprintf('Filter performance satisfactory');
else
disp('Filter performance NOT satisfacory');
disp('Calculating for the 15th harmonic');
R15 = input('Select the suitable resistance in filter circuit in ohms = ');
C15 = input('Select the suitable capacitor in microfarad =');
DenXC15 = 2*pi*15*50*C15;
XC15 = 1000000/DenXC15;
XL15 = XC15;
DenXL15 = 2*pi*15*50;
L15 = XL15/ DenXL15;
L15_mH = L15*1000;
Z15_fundfreqresi = R15*R15;
XC15_fundfreqden = 2*pi*50*C15;
XC15_fundfreq = 1000000/XC15_fundfreqden;
XL15_fundfreq = 2*pi*50*L15;
X15_fundfreq = XL15_fundfreq + XC15_fundfreq;
Z15_fundfreqreactance = X15_fundfreq*X15_fundfreq;
Z15_square = Z15_fundfreqresi + Z15_fundfreqreactance;
Z15_fundfreq = sqrt(Z15_square);
VC15_fundfreq = I15*Z15_fundfreq;
VC15_15harm = I15*XC15;
VC15_voltage = (VC15_fundfreq.^2 + VC15_15harm.^2);
SC_VA = VC15_voltage/XC15_fundfreq;
SC_kVA = SC_VA/1000;
I15_fundfreq = 0.066*I15;

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 SL_VA = (I15.^2 + I15_fundfreq.^2)*X15_fundfreq;
SL_kVA = SL_VA/1000;

disp('R15 in ohm ='); disp(R15);

disp('C15 in microfarad ='); disp(C15);
disp('L15 in mH ='); disp(L15_mH);
disp('SC in kVAR ='); disp(SC_kVA);
disp('SL in kVAR ='); disp(SL_kVA);

Z15=R15;
NumD15=I15*Z15*100;
D15=NumD15/E1;
NumDtotal=(I3*Z3+I13*Z13+I15*Z15+I25*Z25+I37*Z37)*100;
Dtotal=NumDtotal/E1;

disp('Modified D15 = '); disp(D15);

disp('Modified Dtotal = '); disp(Dtotal);

end

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 Appendix - III
Expert System HVDC Fault Localisation
Public Class Form1

Private Sub btn1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)

Handles btnok.Click
btnok.Visible = False
btnbacktomain.Visible = True
If rdb1yes.Checked = True And rdb2yes.Checked = True Then
pnl3.Visible = True
pnl4.Visible = False
pnl5.Visible = False
pnl6.Visible = False
pnl7.Visible = False
End If

If rdb1yes.Checked = True And rdb2yes.Checked = False Then

pnl4.Visible = True
pnl3.Visible = False
pnl5.Visible = False
pnl6.Visible = False
pnl7.Visible = False
End If

If rdb1yes.Checked = False And rdb2yes.Checked = True Then

pnl7.Visible = True
pnl3.Visible = False
pnl4.Visible = False
pnl5.Visible = False
pnl6.Visible = False

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 End If

If rdb1yes.Checked = False And rdb2yes.Checked = False Then

Me.Hide()
Form2.Show()
End If
End Sub

Private Sub btn3ok_Click(ByVal sender As System.Object, ByVal e As

System.EventArgs) Handles btn3ok.Click
If rdb3yes.Checked = True Then
PictureBox1.ImageLocation = "D:\Documents\Visual Studio
2005\Projects\Electronics\Images\POLE STARTED.jpg"
MsgBox("Pole Started Against Opend Ended DC Line", MsgBoxStyle.OkOnly,
"Result..")
Else
MsgBox("Protection System Malfunction", MsgBoxStyle.OkOnly, "Result..")
End If
End Sub

Private Sub btnbacktomain_Click(ByVal sender As System.Object, ByVal e As

System.EventArgs) Handles btnbacktomain.Click
btnok.Visible = True
btnbacktomain.Visible = False
pnl3.Visible = False
pnl4.Visible = False
pnl5.Visible = False
pnl6.Visible = False
pnl7.Visible = False
End Sub

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 Private Sub btn4ok_Click(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles btn4ok.Click
If rdb4yes.Checked = True Then
pnl5.Visible = True
pnl3.Visible = False
Else
pnl6.Visible = True
pnl5.Visible = False
pnl3.Visible = False
End If
End Sub

Private Sub btn6ok_Click(ByVal sender As System.Object, ByVal e As

System.EventArgs) Handles btn5ok.Click
If rdb5yes.Checked = True Then
MsgBox("Reverse Power", MsgBoxStyle.OkOnly, "Result..")
pnl5.Visible = False
PictureBox1.ImageLocation = "D:\REVERSE POWER.jpg"
Else
MsgBox("Protection System Malfunction", MsgBoxStyle.OkOnly, "Result..")
pnl5.Visible = False
End If
End Sub

Private Sub btn6ok_Click_1(ByVal sender As System.Object, ByVal e As

System.EventArgs) Handles btn6ok.Click
If rdb6yes.Checked = True Then
MsgBox("Control System Malfunction", MsgBoxStyle.OkOnly, "Result..")
Else
MsgBox("Other Fault", MsgBoxStyle.OkOnly, "Result..")
End If

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 End Sub

Private Sub btn7ok_Click(ByVal sender As System.Object, ByVal e As

System.EventArgs) Handles btn7ok.Click
If rdb7yes.Checked = True Then
MsgBox("Converter Ground Fault", MsgBoxStyle.OkOnly, "Result..")
Else
PictureBox1.ImageLocation = "D:\Documents\Visual Studio
2005\Projects\Electronics\Images\Graphic223.jpg"
MsgBox("Converter AC Side Fault", MsgBoxStyle.OkOnly, "Result..")

End If
End Sub

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As

System.EventArgs) Handles MyBase.Load
Me.Height = 700
Me.Width = 1200
End Sub

Private Sub btn8ok_Click(ByVal sender As System.Object, ByVal e As

System.EventArgs) Handles btn8ok.Click
If rdb8yes.Checked = True Then
pnl9.visible = True
Else
pnl10.Visible = True
End If
End Sub

Private Sub btn9ok_Click(ByVal sender As System.Object, ByVal e As

System.EventArgs) Handles btn9ok.Click

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 If rdb9yes.Checked = True Then
MsgBox("Ground Fault on Metalic Rerutn", MsgBoxStyle.OkOnly, "Result..")
Else
MsgBox("Open Circuit on Metalic Return", MsgBoxStyle.OkOnly, "Result..")
End If
End Sub

Private Sub btn10ok_Click(ByVal sender As System.Object, ByVal e As

System.EventArgs) Handles btn10ok.Click
If rdb10no.Checked = True Then
MsgBox("Protection System Malfunction", MsgBoxStyle.OkOnly, "Result..")
Else
pnl11.visible = True

End If
End Sub

Private Sub btn11ok_Click(ByVal sender As System.Object, ByVal e As

System.EventArgs) Handles btn11ok.Click

End Sub

Private Sub btn12ok_Click(ByVal sender As System.Object, ByVal e As

System.EventArgs) Handles btn12ok.Click
If rdb12yes.Checked = True Then
MsgBox("DC Line Fault", MsgBoxStyle.OkOnly, "Result..")
pnl12.Visible = False
pnl11.Visible = False
pnl13.Visible = True
Else
MsgBox("Protection System Malfunction", MsgBoxStyle.OkOnly, "Result..")

200
 End If
End Sub

Private Sub btn13ok_Click(ByVal sender As System.Object, ByVal e As

System.EventArgs) Handles btn13ok.Click
Dim b As Double
b = (753 + (txt1.Text - txt2.Text) * 0.00001 * (3.16 * 0.001) * (3 * 100000000)) / 2
MsgBox("Distance =" + b, MsgBoxStyle.OkOnly, "Result..")
pnl11.Visible = False
pnl10.Visible = False
End Sub

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As

System.EventArgs) Handles Button1.Click
PictureBox1.ImageLocation = "D:\Documents\Visual Studio
2005\Projects\Electronics\Images\Graphic22.jpg"
pnl10.Visible = False
pnl11.Visible = False
pnl12.Visible = False
pnl13.Visible = False
pnl3.Visible = False
pnl4.Visible = False
pnl5.Visible = False
pnl6.Visible = False
pnl7.Visible = False
pnl8.Visible = False
pnl9.Visible = False
btnok.Visible = True
btnbacktomain.Visible = False
End Sub
End Class

201
Public Class Form2

Private Sub btn3ok_Click(ByVal sender As System.Object, ByVal e As

System.EventArgs) Handles btn3ok.Click
If rdb1yes.Checked = True Then
pnl2.Visible = True
pnl3.Visible = False
Else
MsgBox("Protection System Malfunction", MsgBoxStyle.OkOnly, "Result..")
Me.Hide()
Form1.Show()
End If
End Sub

Private Sub btn12ok_Click(ByVal sender As System.Object, ByVal e As

System.EventArgs) Handles btn12ok.Click
pnl2.Visible = False
If rdb3yes.Checked = True Then
MsgBox("DC Line Fault", MsgBoxStyle.OkOnly, "Result..")
pnl4.Visible = True
Else
MsgBox("Protection System Malfunction", MsgBoxStyle.OkOnly, "Result..")
Me.Hide()
Form1.Show()
End If
End Sub

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As

System.EventArgs) Handles Button1.Click
If rdb2yes.Checked = True Then

202
 pnl3.Visible = True
pnl2.Visible = False
Else
MsgBox("Protection System Malfunction", MsgBoxStyle.OkOnly, "Result..")
Me.Hide()
Form1.Show()
End If
End Sub

Private Sub btn11ok_Click(ByVal sender As System.Object, ByVal e As

System.EventArgs) Handles btn11ok.Click
Dim b As Double
Dim a, c, d As Long
a = Val(TextBox1.Text)
c = Val(TextBox2.Text)
d=a-c
b = (753 + (d * 0.0948)) / 2
'b = ((753 + d * 0.00001 * (3.16 * 0.001) * (3 * 100000000)) / 2)
Label4.Visible = True
Label2.Text = b
End Sub

Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As

System.EventArgs) Handles Button2.Click
Me.Hide()
Form1.Show()
End Sub
End Class

203
 Acknowledgement

I am pleased to acknowledge my indebtedness to my guide Dr. W. Z. Gandhare, Principal

of Government College of Engineering Aurangabad, for his innovative and invaluable
suggestions in completing this work. I am thankful to him for his gracious encouragement,
pursuance for completion of this work and very valued constructive guidance in reviewing
the laboratory results of this work.

I am thankful to our HOD Dr. A. G. Thosar Madam for her continuous support and
inspiration throughout the completion of this thesis.

My Sincere thanks to Er. R. S. Parulkar, MSETCL, for the pains taken by him throughout
this work. My thanks to Er. Sonkawade, MSETCL for his help provided during simulation.
My gratitude towards Mrs. Puja W. Gandhare for tolerating the inconvenience caused.

I express my sincere thanks towards Dr. Waliwadekar V.N. and Dr. Venkatesh for their
guidance and inspiration.

I am very much thankful to my all colleagues of Department of Electrical Engineering, Prof.

V. A. Hambire, Prof. Kala, Prof. Mrs. Bhole, Prof. Pawar, Prof. Bhasme,
Prof. Swami, Prof. Shinde, Prof. S. S. Kulkarni, Prof. Chalwad, Prof. Mohod for their
really kind cooperation always. Thanks to supporting staff.

My thanks to Ravi, Pankaj, Subhash, Ganesh, Mrs. Lata, Mrs. Mangal and Mrs. Meera for
their continuous assistance. I am also thankful to my friends, well wishers and all those who
have helped me directly or indirectly in the completion of this project.

Last but not the least I would like to thank Almighty for his blessings, my all family
members Kaka, my Sasubai, Baba and Surekha, especially my husband Abhay and
daughters Sai, Ila for their constant patience, cooperation, encouragement, motivation, the
ingredients needed for success, without which the completion of this thesis would have been
a distant dream.

Mrs. Vandana A. Kulkarni

204