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SPECIAL
COMPONENTS OF TALCHER – KOLAR BIPOLAR HVDC Lecture by P.RANGA RAO Chief Manager / Kolar
HVDC EQUIPMENTS
What are the Special Components of HVDC?
MAIN COMPONENTS OF HVDC 1. 2. 3. 4. 5.
6. 7. 8. 9. 10. 11. 12.
Converter Transformer Valve Hall AC Harmonic Filters Shunt Capacitors DC Harmonic Filters Smoothing Reactors DC Current / Voltage measuring devices Valve Cooling / Ventilation System Valve Timing PT VESDA Electrode Station Repeater Station
Basic Components of HVDC Terminal Converter Xmers AC Harmonic 400 kV filters
DC Line
Smoothing Reactor
DC Filter
Electrode station
AC Shunt Capacitors
Valve Hall -Thyristors
Valve Cooling / Ventilation system
-Control & Protection -Telecommunication
CONVERTER TRANSFORMER
400KV SIDE BUSHING
STAR BUSHINGS
DELTA BUSHING
Converter Transformer
CONVERTER TRANSFORMERS
Three Singe Phase Transformers for each Pole Each Transformer is of Three Windings
Winding -1 connected to 400KV side in Star Winding -2 connected to one six pulse bridge in Star Winding -3 connected to second six pulse bridge in Delta
Easy transportation
FEATURES OF CONVERTER TRANSFORMERS
Automatic onload tap changer control with appropriate make and break capacity Extra insulation due to DC currents Proper conductors and magnetic shunts to take care of the extra losses due to harmonic currents Very rugged and reliable OLTC as tapchanging is a integral means of conversion process and control.
Converter Transformer Ratings •Type of converter transformer
: Single phase three windings
•Rated power of line / star / delta winding (MVA) : •Rated current of line / star / delta winding (A):
•Rated Voltage of 400/√3/210.3/√3/210.3
Line/star/delta
397/198.5/198.5 1719/1635/944
winding
(No-load):
•Tap changer (voltage range) •Tap changer steps
: -5 % to +20 % : 16 to -4 (21 steps)
•Tap changer current capacity
: 2X2000A
•Cooling arrangement
: ODAF
Converter Transformer Ratings
No load losses – 192KW Load losses - 760KW @75°C Oil type – Napthanic, Shell Diala Bushings
Line side – oil filled Valve side – Y – SF6 filled Valve side – D – RIP condenser Total weight – 461 Ton Oil weight – 118.7 Ton
Converter Transformer Connection Valve Hall 1-ph 3 winding Converter Transformer
D Y
R
D Y
Y
D Y
B Outdoor
Converter Transformer Cooling control
Automatic daily changeover of cooling pumps and fans 5 groups of fans and pumps Each group – One oil circulating pump & 3 cooling fans 4 groups will be in service with 2 fans each One redundant group – changeovers every day Extra fans will switch ON when winding temperature > 75ºC Redundant group will switch ON when winding temperature >85ºC WTI Alarm - 115ºC WTI Trip - 130ºC OTI Alarm - 85ºC OTI Trip - 95ºC
Converter Transformer internal connection
HVDC VALVE HALL LAYOUT
Multiple Valve Unit • Indoor type • Air insulation • Direct water cooling of all components in the valve producing losses • Application of single thyristors with a high current carrying and voltage blocking capability (no parallel connection of thyristors) • Optoelectronic firing and monitoring system from the ground to thyristor potential and vice versa without intermediate electronics • Monitoring of the status of all thyristor levels during operation • Protective firing of the thyristors as back up firing for self protection of the valves against high over voltages in forward direction • Direct parallel connected surge arresters to each valve
Valve Hall Layout Cross Section
Converter Valves
Converter Transformer Smoothing Rector
DC Bushing
Valve Hall
MULTIPLE VALVE UNIT Grd Quadruplevalve
Valve Arrester
AC
Multiple Valve Unit
D Y Y
AC
DC
Circuit Diagram of the Converters for Pole 1
Valve Tower side view
1. AC Terminal 2. DC Terminal 3. Cooling Water Inlet 4. Cooling Water Outlet 5. Fiber Optic Cables Tubes
6. Thyristor Module 7. Insulator 8. Arrester 9. Screen
• Max. length of fibre optic cables in quadruple valve Lmax = 17.5m • Weight of quadruple valve without arresters: approx. 19300 kg • All dimensions in mm
Valve Tower top view / 3D view
• Max. length of fibre optic cables in quadruple valve Lmax = 17.5m • Weight of quadruple valve without arresters: approx. 19300 kg • All dimensions in mm 1. AC Terminal 6. Thyristor Module 2. DC Terminal 7. Insulator 3. Cooling Water Inlet 8. Arrester 4. Cooling Water Outlet 9. Screen 5. Fibre Optic Cables Tubes
Valve Structure Valve Section / tier
Single Valve
Quadra Valve
Hierarchy of valve structure
Each Thyristor level consists
•Thyristor •Snubber circuit – to prevent high dv/dt •Snubber Capacitor
•Snubber Resistor •Valve Reactor – to prevent high di/dt •Grading Resistor – to equilize the potential across all the levels in a valve – static equalizing •Grading capacitor – dynamic equalizing
Components in one valve Component Thyristor Snubber Capacitor Snubber Resistor Valve Reactor Grading Capacitor Grading Resistor Valve arrester
Population at Talcher 84 84 84 24 6 84 1
Population at Kolar 78 78 78 24 6 78 1
TE card
84
78
Components in one Pole Component Thyristor Snubber Capacitor Snubber Resistor Valve Reactor Grading Capacitor Grading Resistor Valve arrester TE card
Population at Talcher 1008 1008 1008 288 72 1008 144 1008
Population at Kolar 936 936 936 288 72 936 144 936
Thyristor Module GRADING CAPACITOR
SNUBBER CAPACITOR SNUBBER RESISTOR
COOLING PIPE-PEX
THYRISTOR
TE CARD
FIBRE OPTICS
Thyristor Modular Unit top view
Thyristor Modular Unit Detailed View of Thyristor Stack
Eastern Terminal (Talcher)
Southern Terminal (Kolar)
14 Thyristors
13 Thyristors
Thyristor Modular Unit Schematical Cooling Circuit
Eastern Terminal (Talcher) 14 Thyristors Z = Cooling Water Inlet A = Cooling Water Outlet
Southern Terminal (Kolar) 13 Thyristors
Composition of an HVDC Valve Thyristor level TL
=
+
Gate unit
Heat sinks
+
+
1
+
Valve section
Note VS
TL
=
+
1 TL k Valve
VS =1
+ VS
n
k
Fibre optic + system
VS
is the smallest repeatable electrical unit of a valve, mech anical sub-units may contain multiple or sub-devided valve sections
Coolant distrib.
+
Insulating structure
Block Diagram of Thyristor Electronic
1 Light Receiver 2 Light Transmitter 3 Thyristor Voltage Detection 4 Logic
5 Gate Pusle Amplifier 6 Back Up Trigger Circuit (BTC) 7 Energy Supply
Multi-Arm Fibre Optic Cable Used for Monitoring Receiver Side
Emitter Side
1 Protective sleeves in red colour 2 7 continuous single fibre cables
3 Labelling with markers 4 Designation on shrinking tube
Multi-Arm Fibre Optic Cable with Signal Mixing Used for Triggering Emitter Side
Receiver Side
1 Protective sleeves in blue colour 2 Fibre cables statistically mixed
3,5 Labelling with markers 4 Designation on shrinking tube
Thyristor T1501 N75 T - S34 (1) Features: • High-power thyristor for phase control • Ceramic insulation • Contacts copper, nickel plated • Anode, Cathode and gate pressure contacted • Inter digitised amplifying gate
Applications: • HVDC-Transmissions • Synchro- drivers • Reactive-power compensation • Controlled Rectifiers
Internal Structure of Thyristor
Thyristor T1501 N75 T - S34 (2) - Electrical Maximum Ratings • Repetitive peak off-state voltage
VDRM = 7.5 kV at TVJ = +5°C...120°C
• Repetitive peak reverse voltage
VRRM = 7.5 kV at TVJ = +5°C...120°C
• Non-repetitive peak off-state voltage
VDSM = 8.0 kV at TVJ = +5°C...120°C
• Non-repetitive peak reverse voltage
VRSM = 8.3 kV at TVJ = +5°C...120°C
• Surge-on state current
ITSM = 22 kA at TVJ = +90°C, 50 Hz Sinus, VR
=0V
• Critical non-rep. rate of rise of on-state current
di/dtcr = 160 A/µs
• Critical rate of rise of on-state voltage
dV/dtcr = 8600 V/µs at TVJ = +90°C
at TVJ = +90°C, VD = VDRM
Thyristor T1501 N75 T - S34 (3) - Electrical Characteristic Ratings • Off-state current
ID = 500 mA at TVJ = +90°C, VD = VDRM
• Reverse current
IR = 500 mA at TVJ = +90°C, VR = VRRM
• On-state voltage
VT = 2.7 kV at TVJ = +90°C, ITM = 4000 A (stat. 50%/90% value)
• Circuit-commuted recovery time
tq = max. 800 µs at TVJ = +90°C, ITM = 4000 A di/dt = -4 A/µs, VR = 100 V dV/dt = 100 V/µs, VD = 5000 V
• Gate trigger current
IGT = 400 mA at TVJ = +25°C, VD = 12 V
• Gate trigger voltage
VGT = 3 V at TVJ = +25°C, VD = 12 V
Thyristor T1501 N75 T - S34 (4) - Thermal and Mechanical Ratings • Operating junction temp. range
TVJ = +5°C...+120°C
• Storage temp. range
Tstg = -50°C...+60°C
• Thermal resistance
Rth JC = 0.0064 K/W
• Mounting force
fm = 63 kN...91 kN
• Weight
m = 3.9 kg
• Creepage distance
dcreep = 49 mm
• Air distance
dair = 20 mm
Valve Reactor - Electrical and Mechanical Ratings • Voltage-time area
= 80mVs ±10%
• Saturated part of main inductance
LH = 0.55 mH ±10%
• Reactor current
ID max = 1270 A
Current and Voltage Characteristic of the Valve Reactor
Valve Reactor - Dimensional Drawing
Grading Capacitor - Electrical and Mechanical Ratings • Capacity
C = 2.4 µF ±3%
• Nominal voltage
UN = 58 kV
• Periodical max. voltage
Umax = 88 kV
• Short time max. impulse voltage
Us = 8700 V
• Nominal effective current
IN = 1 A
• Periodical max. current
Imax = 100 A
• Operating frequency
f = 50/60 Hz
• Cooling type
self-cooling
• Weight
approx. 25 kg
• Impregnation
SF6 gas
Grading Capacitor - Dimensional Drawing
Snubber Circuit Resistor
Resistance R
45
Tolerance
± 3%
Cooling
Water
Snubber Circuit Capacitor X View X
Capacitance
1.6 µFd
Tolerance
+/-5%
Insulation
SF6
DC Smoothing Reactors
Smoothing Reactor - Purpose
Connected in series in each converter with each pole Decreases harmonic voltages and currents in the DC line Smooth the ripple in the DC current and prevents the current from becoming discontinuous at light loads Limits crest current (di/dt) in the rectifier due to a short circuit on DC line Limits current in the bypass valve firing due to the discharge of the shunt capacitances of the dc line
DC Smoothing Reactor ratings •Two Smoothing Reactors per pole •Inductance - 125mH
•Nominal DC Voltage – 500KV •Max DC Voltage – 515KV •BIL – 950/1425KV
DC Smoothing Reactor ratings
•Continuous current - 2000A •Continuous Over load current - 2200A •Type – Air Cored Dry type •Natural Air Cooled reactors •Location : Outdoor •Total mass – 30 Ton •Temperature Class - F
HARMONIC FILTERS
Conversion process generates – Harmonics AC side Harmonics- Current harmonics
Generated harmonics – (12n ± 1) harmonics n = 1,2,3…. Predominant harmonics – 11,13,23,25,35,37 Additionally 3rd harmonics
DC side Harmonics- Voltage harmonics
Generated harmonics – (12n) harmonics n = 1,2,3…. Predominant harmonics – 12,24,36
Disadvantages of Harmonics
Over heating and extra losses in generators Over heating and extra losses in motors Instability in the converter control Interference with telecommunication systems Over voltages due to resonance
AC Filters - Kolar ITEM
A
B
C
Filter sub bank
DT 12/24
DT 3/36
Shunt C
Rating (3 ph., 400 kV)
MVAr 120
97
138
No.of 3 phase Banks
-
6
3
5
HV-Capacitor C1
μF
2.374
1.85
2.744
HV-Reactor L1
mH
16.208
5.444
1.602
HV-Resistor R1
ohms
420
300
-
LV-Capacitor C2
μF
4.503
3.759
-
LV-Reactor L2
mH
7.751
204.2
-
LV-Resistor R2
ohms
-
1500
-
12/24 Double Tuned Filter – 120 MVAr
C1=2.374µF
L1=16.208mH
R1=420Ω
C2=4.503 µF
L2=7.751mH
11
13
23
Impedance Graph
25
12/24 Double Tuned Filter – Sectional view
Capacitor Stack
CT
Resistor Reactor
Reactor
3/36 Double Tuned Filter – 97 MVAr
C1=1.85µF
L1=15.444 mH
R1=300Ω
C=23.759µF
L2=204.2mH
R2=1500 Ω
3
35
37
Impedance Graph
3/36 Double Tuned Filter – Sectional view
Capacitor stack
CT
Resistor
Reactor
Reactor
C=23.759µF
Shunt Capacitor – 138 MVAr •No harmonic filtering C1=2.744 µF
L1=1.602 mH
•Supplies MVAr to the grid •Switched into the circuit for voltage control purpose •Capacity – 138 MVAr
Shunt Capacitors-Voltage Improvement
Ratings of Capacitors C1 & C2 of 12/24 filter Type
96 TILP
8 TILR
Make
NOKIAN
NOKIAN
Capacitance ( per ph )
2.37 F
4.50 F
Capacitor Bank 1 phase output
67.4 Mvar
0.94 Mvar
Capacitor Bank Voltages
301 kV
25.5 kV
Capacitor bank currents ( 1 ph )
290 A
404 A
System Frequency
50 Hz
50 Hz
No. of units in series (s)
32
4
No of units in parallel
2+1
2
Total Units (1 ph )
96
8
Unit Capacitance
25.3 F
8.99 F
Capacitor Unit rated output
703 Kvar
115 Kvar
Capacitor unit rated voltage
9406 Volts
6380 Volts
Capacitor Unit rated current
74.7 A
18 A
Capacitor Bank Rating
Electrical connections:
Capacitor Units
Ratings of Resistor of 12/24 filter
Type : EKE/ KLK Resistor DT 12/24 R1 Make : KLK Electro Materials, Spain Resistor material : Stainless Steel Ni-Cr 40 Cooling : Natural Air Temperature Coefficient of resistance : C = 0,00054u / OC Resistance (at nominal current) : 420 ohm MCOV -HV to Ground : 35 kV BIL/ SIL : 325/250 kV Total Losses : 678 kW/356 kW Max. temperature rise for the resistor element: t = 170 °C Inductance : L < 10320 H Thermal Time constant : 400 s Fundamental frequency : 50 Hz Weight : 450 kg
Ratings of Reactors L1 & L2 of 12/24 filter Type
Dry, Air core
Dry, Air core
Make
Trench Limited, Canada
Trench Limited, Canada
Nominal Inductance
mH
16.208
7.751
Tolerance on Inductance
%
+/-0.5
+/-1.0
Nominal Frequency
Hz
50
50
Amps Amps Amps
180 151.7 ( 11th ) 223
180 241.3 ( 11th ) 366
Amps
287
408
kV kV kV
325/250 325/250 150/150
150/150 150/150 95/95
Continuous Current rating Fundamental Major harmonic Geometric sum of Harmonic Current Total Current Stress BIL/ SIL (HV to LV) BIL/ SIL (HV to Ground) BIL/ SIL (LV to Ground)
Ratings of Capacitors C1 & C2 of 3/36 filter Type
90 TILP
4TILR
Make
NOKIAN
NOKIAN
Capacitance (ph)
1.85 F
2.85 F
Capacitor Bank 1 phase output
48.2 Mvar
0.74 Mvar
Capacitor Bank Voltages
288 kV
25 kV
Capacitor bank currents ( 1 ph )
180 A
75 A
System Frequency
50 Hz
50 Hz
No. of units in series (s)
30
4
No of units in parallel
2+1
1
Total Units (1 ph )
90
4
Unit Capacitance
18.5 F
11.4 F
Capacitor Unit rated output
536 KVAr
151 KVAr
Capacitor unit rated voltage
9600 Volts
6500 Volts
Capacitor Unit rated current
55.8 A
23.3 A
Capacitor Bank Rating
Electrical connections:
Capacitor Units
Ratings of Resistor of 3/36 filter Type : EKE/ KLK Resistor (DT 3/36 R1 ) Make : KLK Electro Materials, (Spain) Resistor material : Stainless Steel Ni-Cr 40 Cooling : Natural Air Temperature Coefficient of resistance : C = 0,00054u / OC Resistance (at nominal current) : 420 ohm MCOV -HV to Ground : 35 kV BIL/ SIL : 325/250 kV Total Losses : 678 kW/356 kW Max. Temperature rise for the resistor element: t = 170 °C Impulse energy at warm resistor : 230 kJ Inductance : L < 10320 H Thermal Time constant : 400 s Fundamental frequency : 50 Hz Weight : 450 kg
Ratings of Reactors L1 & L2 of 3/36 filter Type
Dry, Air core
Dry, Air core
Make
Trench Limited, Canada
Trench Limited, Canada
Nominal Inductance
mH
5.444
204.2
Tolerance on Inductance
%
+/-0.5
+/-1.0
Nominal Frequency
Hz
50
50
Amps Amps Amps
167 43.2 ( 13th ) 66
181 23.3 (13th ) 24
Amps
180
183
kV kV kV
325/250 325/250 250/250
250/250 250/250 95/95
Continuous Current rating Fundamental Major harmonic Geometric sum of Harmonic Current Total Current Stress BIL/ SIL (HV to LV) BIL/ SIL (HV to Ground) BIL/ SIL (LV to Ground)
Ratings of Capacitors in Shunt C Type
96 TILP (138 Mvar)
Make
BHEL
Capacitor Bank Rating
Capacitance ( ph )
2.744 F (+/- 1%)
Capacitor Bank 1 phase output
63.8 Mvar
Capacitor Bank Voltages
272kV
Capacitor bank currents ( 1 ph )
234.4 A
System Frequency
50 Hz
Electrical connections: No. of units in series (s)
38
No of units in parallel
4
Total Units (1 ph )
152
Capacitor Units Unit Capacitance
26.07 F
Capacitor Unit rated output
419.6 Kvar
Capacitor unit rated voltage
7.16 kV
Capacitor Unit rated current
58.6 A
Ratings of Reactors in Shunt C Type
Dry, Air core
Make
Trench Limited, Canada
Nominal Inductance
mH
1.602
Tolerance on Inductance
%
+/-1.5
Nominal Frequency
Hz
50
Continuous Current rating Fundamental Major harmonic Geometric sum of Harmonic Current Total Current Stress
Amps Amps Amps Amps
232 49.6 13th ) 78 245
BIL/ SIL (HV to LV) BIL/ SIL (HV to Ground) BIL/ SIL (LV to Ground)
kV kV kV
325/250 325/250 95/95
DC Filter 12/24 TYPE
C1=1800 nF
R1=400 Ω
L1=14.71 mH
C1=5700 nF
L2=8.19 mH
Ratings of Capacitors C1 & C2 of 12/24 filter
Make
ABB
ABB
Nominal Capacitance
nF
1800
5700
Tolerance of Nominal Capacitance
%
+/- 0.5
+/-1.0
Maximum DC Voltage Arithmetic sum of Harmonic Voltage Total Voltage Stress
kV kV kV
538 59 621
5.3 7.5
Geometric sum of Harmonic Current A
63
70
BIL/ SIL (HV to LV) BIL/ SIL (HV to Ground) BIL/ SIL (LV to Ground)
1300/1175 1425/1300 450/350
150/150 250/250 150/150
kV kV kV
Ratings of Resistors of 12/24 & 12/36 filter
Make
KLK Electro Materials, Spain
Type
KLK DT 12/24
Resistance at nominal current
Ω
400
Tolerance %
%
+/-5
Total losses
kW
160
Rated frequency
Hz
50
BIL/ SIL (HV to LV) BIL/ SIL (HV to Ground) BIL/ SIL (LV to Ground)
kV kV kV
325/250 325/250 95/95
Ratings of Reactors of 12/24 filter Make
Trench Limited, Canada
Type
Dry, Air core
Dry, Air core
Nominal Inductance
mH
14.71
8.19
Tolerance on Inductance
%
+/-1
+/-1
Continuous Current rating DC Current Major harmonic Geometric sum of Harmonic Current Total Current Stress
Amps Amps Amps Amps
0 43 (12th ) 60 60
0 110 (12th ) 120 120
BIL/ SIL (HV to LV) BIL/ SIL (HV to Ground) BIL/ SIL (LV to Ground)
kV kV kV
250/250 450/250 250/250
150/150 250/250 150/150
Minimum Creepage Distance
mm
800
400
DC Filter 12/36 TYPE
C1=1800 nF
L1=7.21 mH
R1=400 Ω
C1=3300 nF
L2=12.68mH
Ratings of Capacitors C1 & C2 of 12/36 filter
Make
ABB
ABB
Nominal capacitance
nF
1800
3300
Tolerance of Nominal Capacitance
%
+/- 0.5
+/-1.0
Maximum DC Voltage Arithmetic sum of Harmonic Voltage Total Voltage Stress
kV kV kV
538 61 624
9.2 13
Geometric sum of Harmonic Current
A
65
76
BIL/ SIL (HV to LV) BIL/ SIL (HV to Ground) BIL/ SIL (LV to Ground)
kV kV kV
1425/1050 1425/1050 325/250
1425/1050 1425/1050 325/250
Internal
Internal
Type of Fusing
Ratings of Reactors of 12/36 filter Make
Trench Limited, Canada
Type
Dry, Air core
Dry, Air core
Nominal Inductance
mH
7.21
12.68
Tolerance on Inductance
%
+/-1
+/-1
Continuous Current rating DC Current Major harmonic Geometric sum of Harmonic Current Total Current Stress
Amps Amps Amps Amps
0 44 (12th ) 65 65
0 116 (12th ) 123 123
BIL/ SIL (HV to LV) BIL/ SIL (HV to Ground) BIL/ SIL (LV to Ground)
kV kV kV
250/250 450/250 250/250
150/150 250/250 150/150
Minimum Creepage Distance
mm
1050
400
DC MEASURING DEVICES
Measurement on DC side for control, monitoring and Protection AC CTs cannot be used on DC side – saturation DC current measuring devices – OPTODYNE
DC shunt – low value resistor mV drop from the shunt will be taken for determining the current To solve insulation problems – electrical signals are converted to optical at the shunt and at control system converted to electrical Supply for the conversion process is obtained from the control panels in the form of optical power
DC voltage divider
Capacitive & resistor divider circuit Drop across the resistor scaled for determining the voltage Optical conversion process is same as the current measuring device Details follows……
DC Current Measuring Device (OPTODYN) Lay out at HVDC Kolar 6 UdL
6 IdH
4 IdL
Line 1
Pole1 4 UdN 2 IdN
4 IdE
IdN
IdE
2
4
8 Idee1 Idee2 UdN 4
Idee3 8
8 Current Measuring Devices 11Nos (4 HV+7 LV) Voltage Dividers 04 Nos ( 2 HV+2 LV)
Pole2
IdH 6
Electrode lines
Line 2
IdL UdL 6
4
Example for the Use of the Hybrid Optical Sensor Iron Core Inductive CT
Shunt
Rogowski Air Core CT
HV/EHV-Line
TM
OPTODYN
Ground Level
Capacitive Resistance Inductive Voltage Voltage Divider Voltage Divider Transformer
Functional Concept Shunt Analog/ Digital
Optical
Digital/ Optical
Id
Signal fibre
Electrical Energy
Power fibre
Optical Energy
Digital
Digital control/ protection system SIMADYN D
Optical Energy Electrical Energy
Sensor Head at high voltage level Fibre optical cable
Power supply
Control/ Protection system at ground level
Power Supply of Sensor Head Isolation of Synchronising signal from power supply voltage level (carrier)
LOW POWER Electronics at the Sensor
Power Supply Output for Preconditioning and Transmitter Electronics
Voltage Regulator
Photocell-Array (Power Converter)
Optical Fiber
LASER
LASER Driver
Diode Array
and Protection
5 VDC ca. 25 W for up to 9 channels from SIMADYN D System Power Supply
Optical Interface, Optical Power-Module (as part of the Optical Interface Card)
Optical Data Transfer
BURDENRESISTOR (at CT only)
Fast Transients+ RFI-Prot.
BUFFER
ANTIALIASING FILTER
12 Bit A/DConverter
Optical Fiber
OPTICALRECEIVER
Optical Interface
BUFFER
Digital Data for processing in Control and Protection Systems
OPTICALTRANSMITTER
Components 1
8
1 Ohmic Shunt at High DC Voltage Level for Direct Current Measuring
11 6
3 7
2
2 Voltage to Light Telegram Conversion 3 Fibre Optic Transmission to Ground Level 4 Composite Insulator
10 5 Control or Protection System 6 Light Pulses for Power Supply 4
7 Power Supply for Sensor Head 8 Rogowski Coil for Harmonic Current Measuring 9 Control of Active DC Filter
9
5
10 Hybrid Direct Current Measuring System with Fibre Optic Transmission 11 Sensor Head
Current measuring device – components
Redundancy Concept
complete redundancy from sensor head via FO cable to control/ protection equipment only one Analog/ Digital conversion per signal path direct digital signal processing
Shunt
Sensor Head
Pole control System 1
Sensor Head
Pole control System 2
Sensor Head
Protection System 1
Sensor Head
Protection System 2
Id
high voltage level; switchyard
common composite insulator and fibre optic cable
ground level; control building
DC Measuring Scheme: Conventional DC Transducer Conventional DC Measuring Scheme: Total Accuracy < +-0,8%
typical +- 0,1%
typical +- 0,2%
Conventional DC Transducer: Accuracy < +-0,5%
Digital Control System 0
0
Digital Signal Signal
Isolation
Amplifier
Amplifier
Processor
0 to redundant control system or Isolation Amplifier
protection system
DC Measuring Scheme: HybridOptical DC Measuring System Hybrid-Optical DC Measuring System: Total Accuracy < +-0,75%
Current Sensor: typical +- 0,2%
typical +- 0,5%
0,0%
OPTODYN
Digital Control System
Electronic Sensor Head 0
Digital Signal Processor
Comparision to Conventional Solution Comparison between Hybrid-Optical a Conventional DC Measuring System The weight of the new measuring device is reduced from 4,000 kg to 100 kg No additional Post Insulators No electromagnetic interference (EMI) due to fibre optic links Full redundancy up to the measuring location Excellent dynamic performance
a
s
Picture 2
Hybrid-Optical Measuring Device
Measuring Shunt
Sensor Head Box
Composite Insulator
incl. Fiber Optics
Connection Box
Sensor Head Box with Sensors
Assembly of Shunt
OPTODYN Sensor
Analoge Input Signal from Shunt
Optical Data Link
Optical Power Supply Link
Summary Measures DC current quantities up to the range of 18,000 A High voltage insulation level up to 500 kV rated DC voltage Current measuring by a high precision shunt Light construction High insulation capability also under extreme environmental conditions Less pollution due to less electrostatic potential of silicon surface
Hydrophobic silicon material reduces risk of leakage currents No electromagnetic interference by use of fibre optic cables
Summary Optical powered electronics at high voltage level Optical signal transmission Optical receivers directly placed in the control or protection system Separate channels for control and protection including their redundant subsystems Excellent dynamic Performance Bandwidth 0 - 7 kHz (depending on application)
Overall system accuracy 0.75 % Signal delay 160 µs Temperature operating range -40 C to +50 C
DC Voltage Measurement
DC Voltage Measurement
System Description
The Valve Cooling System is a single closed loop deionised water system. Heat transfer to the ambient is provided by dry coolers. The Valve Cooling System is for one pole and works independent of other cooling and air conditioning systems.
Spray water will be used if the water temperature rises above controller set point value.
Design Basis Kolar Station
Talcher Station
Maximum Dry Bulb One Hour Average
450C
500C
Minimum Dry Bulb One Hour Average
20C
00C
Total Cooling Capacity
4340kW
4053kW
Water flow
4140 ltr./min
4350 ltr./min
Water Inlet Temperature MAX
500C
500C
Water Outlet Temperature Average
620C
620C
Water Conductivity
<0.5μS/cm
<0.5μS/cm
Redundant Circulating Pumps
One of two
One of two
Spray Water Storage for
24hrs
24hrs
Flow Diagram
VALVE COOLING MAIN PUMP
Two centrifugal circulating pumps One pump - operating Other pump - standby Periodical automatic pump changeover. Changeover to the stand by pump takes place in case of failure of the operating pump Capacity of
Motor – 45KW Pump – 265Cu.m/Hr
VALVE COOLING - MAIN FILTER
In the main water line to the thyristor valves locates a 50 micron filter The filter is used for start up and cleaning and later on for safety, that no particle greater than 50 micron can enter the thyristor valves
VALVE COOLING - MAIN FILTER
Main filter consists of group of filter cartridges as shown in the figure If the filter gets chocked for any reason, differential pressure will be sensed and this warns for maintenance
VALVE COOLING – MAKE UP WATER TANK
A storage tank with a pressure pump is placed on the pump skid for the first filling with deionised water and for compensation of evaporated water during operation The make up water system works automatically and keep the expansion tank water level constant The make up water flows from the storage tank through a 50 μm filter, then the make up water pass the ion exchanger and flows finally into the main water circuit
VALVE COOLING – ION EXCHANGERS
Two ion exchanger chambers are installed on the pump skid The ion exchanger is hydraulically switched in bypass to the main water line A mixture of 50% anion and 50% cation (H+/OH-) is used for the resin Water flows from top to the bottom through the ion exchanger
VALVE COOLING SYSTEM – COOLING TOWERS
Six cooling towers are installed to cool down the fine hot water coming out from the valves One tower consist of two cooling coils with stainless steel tubes and seawater resistance aluminium fins. Two axial type fans are mounted on the top flow. The fans work on the suction side in parallel to the cooling coil surface without baffle sheets. Because there is no baffle sheet, the working fan will cover the whole cooling coil surface, therefore the lost cooling capacity will be less then 50% of the tower.
Each
fan is provided with Variable frequency Drive (VFD). This regulates the speed of the fan depending on the water temperature If one fan fails, the speed of the remaining fans will be increased automatically.
•A spray water distribution pipe with nozzles locates on the top of each cooling coil
•Water will be sprayed over the coil if the water inlet temperature exceeds specified limit
Water Treatment plant
To avoid scaling on the cooling coil fins, the spraying water will be treated by a reverse osmosis* unit. The incoming water from the station supply will be filtered, softened by the reverse osmosis unit and stored in the spray water storage tank. The same water is used to make up the loss in the main water circuit High pressure pumps each of 100% capacity are used for the spray water lines. *slow change in concentration: the flow of a solvent by diffusion through a semi permeable membrane from a more concentrated solution to a less concentrated one, until the concentrations are equalized. It is a major factor in regulating the movement of water into and out of tissues in living organisms.
VALVE COOLING SYSTEM-CONTROL
Controlled by two redundant SIMATIC S95U programmable controller. The PLC working independent of each other. The PLC generates the necessary status, alarm and trip signals for the station control. The inlet water temperature to the Thyristor valve modules is maintained at constant value for every load and ambient conditions. A digital process controller SIPART DR22 is used for the temperature control The controller output signal is used for the set point of the cooling fan speed. Start and stop signal for the fans is given by the PLC. 80 KVA UPS is provided as backup power supply. Since the outage of main pump generates immediate trip to the pole.
Expansion Tank
The expansion tank is place on the highest point of the cooling system. The tank size is big enough to store the expanded fine water volume. The expansion tank is an open type expansion tank, the construction of the tank allows the air to come in contact with the water, but dust can not enter the tank. Thyristor valve manufacturer requires a oxygen saturated water, therefore the need of an open system. The tank is connected to the suction side of the main water line, the connection to the discharge main water line will be used for circulation and for venting.
Valve Hall Ventilation system Flow Diagram
AIR INLET 5m ABOVE GROUND LEVEL
Valve Hall Ventilation system
Consists of the primary circuit (Air Ventilation Circuit) and Control System Open loop system – supply air will taken in and left out through the exhaust dampers One ventilation system is in operation while the other one is in stand by mode. The outdoor air will be entering the unit by a concrete block duct in a level of 5 m to avoid the dust concentration at the floor level. The supply air will filtered in two stages – pre filter and fine filter The supply air will be distributed into the valve hall by high speed air nozzles. The exhaust air flows via dampers and weather guard louvers into the atmosphere. A bypass damper and a heater enables the circulation of air from the valve hall back to the unit in case of no load or during start up. Through out the process, positive pressure will be maintained in the valve hall to prevent dust to enter the valve hall. Positive pressure is maintained with the automatic control of exhaust dampers
Valve Hall Ventilation system-components
One single ventilation unit consist of
One axial type fan speed regulated
One electrical heater
One air filter bag type as a pre filter
One air filter bag type as a high efficiency filter
One Supply air damper with DC drive
One Return air damper with DC drive
One Bypass or re-circulating damper with DC drive
The two exhaust dampers with DC drives combined with a weather guard louver, as well as the air inlet weather guard louver working together with the two ventilation units. In case of failure of the operating unit, a switchover to the stand by unit takes place.
A periodically automatic switchover is also provided by a programmable timer. The timer can operate in automatic or manual mode.
Ventilation system - Control
The ventilation system will be controlled by two SIMATIC S95U programmable controller. The PLC‘s are working independent from each other; a switch off of one PLC for repair, replacement or service will not disturb the ventilation system operation. The input signals from the single sensor will be wired parallel on the two PLC. The output signal from the PLC working on the same relay coupled by a diode. The PLC generates also the necessary status, alarm and trip signals for the station control.
KOLAR SINGLE LINE DIAGRAM
AC PLC (Noise) Filter
AC PLC FILTER Equipment Designation
Kolar
Talcher
=20C08.C C1/TD, C2/TD =10C03.C C1/TD, C2/TD =20C10.C C1/TD, C2/TD =10C05.C C1/TD, C2/TD
Number of single phase units
6
6
Rated Capacitance
40 nF
80 nF
Nominal voltage
400 kV
400 kV
Short -time current (1s)
40 kA
40 kA
Basic Insulation level (BIL)
1425 kV
1425 kV
Switching Insulation level (SIL)
1050 kV
1050 kV
10500 mm
10500 mm
Min creepage distance
VALVE TIMING PT •Inductive Voltage Transformer - Connected to converter transformer 400 KV side •Pole control gets the zero crossings of the Voltage on line side and uses this as the reference for generating firing signals for the valves
•This PT is used only for firing signal generation – not used for nay protection task
VALVE TIMING PT
•It is inductive voltage transformer •Oil filled – Oil type Shell Diala D •Make – Trench. •Primary/secondary voltage ratio – 400√3/110 √3
VESDA SYSTEM
VESDA – VERY EARLY SMOKE DETECTION & ANALYSER SYSTEM
Air sampling based detection system for early detection of incipient smoke / fire in Valve Hall. Installed in each Valve Hall. Sufficient points are well distributed over each multiple valve structure & inside the ventilation air duct for faster response of hazard. The VESDA detectors are located such that there is no condensation due to temperature differences between the sampled air & the outside temperature. Air is sampled by PVC (red) pipes - no risk of flashover or corona inside the valve hall. The detection system has VESDA laser scanner & laser compact. This gets the signal from the sampling pipes which are of PVC make & are supported at regular interval of 1.5 m. For more sensitivity & easy detection,the sampling area is divided into 4 zones.The detector has 4 alarms namely . Alert Action / Prealarm Fire 1 Fire 2
VLC – VESDA LASER COMPACT VLS – VESDA LASER SCANNER
VESDA - LAYOUT PVC conduit
Vent diameter – 4 mm
End cap – 4 mm VALVE - HALL VESDA laser compact
VESDA - LAYOUT
AIR SAMPLING PVC
VLC
Each detector has separate settings of alarm Level DETECTOR
ALERT
ACTION
FIRE 1
FIRE 2
SCANNER
0.075 %
0.13 %
0.19 %
0.25 %
COMPACT
0.15 %
0.3 %
-----
0.5 %
0.075 %
0.16 %
-----
0.25 %
[ SUPPLY AIR ]
COMPACT [ RETURN AIR ]
NOTE : All values have the unit obscuration / m or Ob / m
In the event of detection of smoke in valve hall
Ventilation system shall be tripped automatically. The exhaust dampers shall be opened. The valve-hall shall be de-energized. The smoke management system shall indicate “smoke evacuation mode”. The audible fire alarm system in the station shall also be activated.
VESDA LASER SCANNER - SPECIFICATIONS
Voltage – 18 to 30 V DC. Power – 5.8 to 9.6 W. Current – 240 to 400 mA. Sensitivity – 0.005 to 20 % Ob/m Operating temperature
Detector ambient : 0 to 39oC Sampled air : 20 to 60oC Humidity : 10-95%RH.
Maximum area of coverage – 2000 m2. Up to 18000 events can be stored on a FIFO basis. Four levels of fault warning – Alert,Action,Fire1,Fire2. Relays – 12 relays rated at 2A @ 30 V DC.
VESDA LASER SCANNER - SPECIFICATIONS
Voltage – 18 to 30 V DC Power – 4 W Current – 170 mA Sensitivity – 0.005 to 20 % Ob/m Operating temperature
Detector ambient : 0 to 39oC Sampled air : 20 to 60oC
Maximum area of coverage – 500 m2 Up to 12000 events can be stored on a FIFO basis Smoke level, alarms & faults with time & date stamp Relays – 3 relays 2A @ 30 V DC
ELECTRODE STATION
Converter requires reference ground for insulation coordination, control & protection DC currents cause corrosion in metallic structures, hence generally the grounding is done at a safe distance away from HVDC stations (30 to 35 Km) Reliability of HVDC System
Eliminates the requirement of a separate line as return path
When one line is faulty then by using earth as return path 50% of rated Bipole power can be transmitted. When one pole trips other pole continues in ground return with over load capacity of that pole thus providing transient stabilty / sudden loss of power During balance bipolar operation no current flows through the ground however it provides a return path
Located at Sidalagatta about 32 km from Kolar Station. Similar station exits at Talcher.
Electrode station - Layout
EARTH ELECTRODE
Conductor type ACSR “Bersimis” Double bundle - 2 x 725.2 Sq.mm Length – 32 Kms DC resistance at 20°C – (0.0421 / 2 ) ohms / km Electrode resistance < 0.3 ohms Electrode – Double ring of diameter 450/320m Each ring consist of a buried coke bed at approx. 2.5 m depth. The outer ring is divided into six sections and the inner ring into two sections Current is distributed by an overhead system to the feeding cables of each electrode section. The cables are connected to the buried electrode. The electrodes are equipped with detecting wells for monitoring the temperature and humidity development of the soil
PLCC SCHEMATIC Pole 1 DC Line
PLCC PANELS
PLCC PANELS
PLCC PANELS
BT PLCC PANELS
BT
BT
BT PLCC PANELS
PLCC PANELS
Pole 2 DC Line KOLAR
BT= BALANCING TRANSFORMER
REPEATER
TALCHER
REPEATER STATION •Repeater station is required due to the long distance of the line - 1400Km (approx.) •Located at Jungareddygudem (Rajahmundry) almost at a distance of 630 km from Kolar •Conventional AC stations don’t require repeater station in between the line •Modulated signals consisting of Data, protection and speech are sent to repeater station from one end over the DC lines •Signals are demodulated, amplified and again modulated and sent to the other end from repeater station – thus working as a signal amplifier
•ABB PLCC panels ETL 580 model are used which works on advanced DSP technology
REPEATER STATIONOther Equipment •PLCC signals are injected to the line through the PLC coupling capacitors •For maintenance works on the PLC equipment, earth switches are provided
•PLCC panels requires 48V DC supply - provided from batteries •Auxiliary supply is be provided from local SEB supply •DG set is provided as backup to the SEB supply