hvdc kolar station.pdf
TRANSCRIPT
7/21/2019 HVDC KOLAR STATION.pdf
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7/21/2019 HVDC KOLAR STATION.pdf
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Kolar
Chintamani
Cudappah
HoodyHosur
Salem
Udumalpet
MadrasB’lore
+/- 500 KV DC line
1370 KM
Electrode
Station
ElectrodeStation
TALCHER
400kv System
220kv system
KOLAR
TALCHER KOLAR SCHEMATIC
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AC System A AC System B
U2U1
Id
Rectifier
Control
Id-Control
Converter
Id: DC Current
Converter Control
Inverter Control
Ud-Control
Converter
Ud: DC Voltage
Reactive Power Control
ReactivePower Control
(AC VoltageLimitationControl)
capacitors capacitors
ReactivePower Control
(AC VoltageLimitationControl)
Sending End Receiving End
Tap Changer Control
Tap Changer
Control
Tap Changer
Control
ACF
ACF ACF
ACF
ACF: AC Filter
What are the basic principles of HVDC Controls?
HVDC Control & Protection
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ADVANTAGES OF HVDC OVER HVAC TRANSMISSION
– CONTROLLED POWER FLOW IS POSSIBLE
VERY PRECISELY
– ASYNCHRONOUS OPERATION POSSIBLE
BETWEEN REGIONS HAVING DIFFERENTELECTRICAL PARAMETERS
– NO RESTRICTION ON LINE LENGTH AS NO
REACTANCE IN DC LINES
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ADVANTAGES OF HVDC OVER HVAC TRANSMISSION
– STABILISING HVAC SYSTEMS -DAMPENING OF POWER SWINGS ANDSUB SYNCHRONOUS FREQUENCIES OF GENERATOR.
– FAULTS IN ONE AC SYSTEMS WILL NOT EFFECT THE OTHER AC
SYSTEM.
– CABLE TRANSMISSION
.
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Points related to operation of HVDC
• Active Power Control• RPC control
– Filter switching seq.
– Limitations by RPC
• Stability Controls – Power Limitations
– Frequency limit controller – Run-backs / Run-ups
– Power Swing damping control
• GRM operation & electrode limitation
• Overload of HVDC
• SPS scheme
• Power / current limits due to protection• Power reversal
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HVDC VALVE HALL LAYOUT
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MULTIPLE VALVE UNIT
AC
DC
ValveQuadruplevalve
Arrester
AC
Grd
MultipleValve
Unit
D
YY
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Circuit Diagram of the Converters for
Pole 1
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Valve Tower top view / 3D view
1. AC Terminal2. DC Terminal3. Cooling Water Inlet4. Cooling Water Outlet5. Fibre Optic Cables Tubes
6. Thyristor Module7. 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
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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
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Components in one valve
Component Population
at Talcher
Population
at Kolar Thyristor 84 78
Snubber Capacitor 84 78
Snubber Resistor 84 78
Valve Reactor 24 24
Grading Capacitor 6 6
Grading Resistor 84 78
Valve arrester 1 1TE card 84 78
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Component Population
at Talcher
Population
at Kolar Thyristor 1008 936
Snubber Capacitor 1008 936
Snubber Resistor 1008 936
Valve Reactor 288 288
Grading Capacitor 72 72
Grading Resistor 1008 936
Valve arrester 144 144TE card 1008 936
Components in one Pole
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Thyristor Module
SNUBBER CAPACITOR
SNUBBER RESISTOR
THYRISTOR
TE CARD
COOLING PIPE-PEX
GRADING CAPACITOR
FIBRE OPTICS
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Thyristor Modular Unit top view
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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
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Internal Structure of Thyristor
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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
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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
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12/24 Double Tuned Filter – 120 MVAr
C2=4.503 µF
R1=420Ω
L2=7.751mH
L1=16.208mH
C1=2.374µF
11 13
23 25
Impedance Graph
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Capacitor Stack
ResistorReactorReactor
12/24 Double Tuned Filter – Sectional view
CT
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3/36 Double Tuned Filter – 97 MVAr
C1=1.85µF
R1=300ΩL1=15.444 mH
C=23.759µFR2=1500 Ω
L2=204.2mH3
35 37
Impedance Graph
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Capacitor stack
ResistorReactor
C=23.759µF
Reactor
3/36 Double Tuned Filter – Sectional view
CT
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Shunt Capacitor – 138 MVAr
C1=2.744 µF
L1=1.602 mH
• No harmonic filtering
•Supplies MVAr to the grid
•Switched into the circuit for voltage
control purpose•Capacity – 138 MVAr
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DC Filter 12/24 TYPE
C1=1800 nF
R1=400ΩL1=14.71 mH
L2=8.19 mH
C1=5700 nF
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DC Filter 12/36 TYPE
C1=1800 nF
R1=400ΩL1=7.21 mH
L2=12.68mH
C1=3300 nF
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STABILITY FUNCTIONS
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STABILITY FUNCTIONS
– Power Limitations
• Always enabled in the control system
• Becomes active once the AC switchyard configuration
for NTPC at Talcher or 400kV S/y at Kolar changes-
refer tables
• Introduced to improve stability in the regions, selfexcitation of generators, failure of control systems etc.
• Power capability depends upon the no. of generators /
lines connected to HVDC
• Automatic limitation of power takes place
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– Frequency limit controller • Stability functions needs to be enabled by the operator
• FLC comes into action if the frequency limits are set
within a band of current frequency
• Enabled automatically during islanding or split busmode at Talcher
• Enabled automatically during split bus mode at Kolar
• Can be enabled individually at Talcher or Kolar
• If telecom is faulty – FLC of Kolar is disabledauotmatically
STABILITY FUNCTIONS
STABILITY FUNCTIONS
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– Run-backs / Run-ups
• If stability functions are enabled, these functions are automatically
enabled
• At present this functions are not programmed
• Automatic ramping up of power is possible with certain conditions• 5 conditions can be programmed / hardware inputs
• Automatic ramping down of power is possible with certain
conditions
• 5 conditions can be programmed / hardware inputs
• Individual run ups/run backs can be enabled or disabled forTalcher/Kolar station
STABILITY FUNCTIONS
STABILITY FUNCTIONS
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– Power Swing damping control
• Stability functions are to be enabled & power swing damping
function to be enabled
• Power Swing Damping function provides positive damping to the
power flow in the parallel AC system• This function becomes active automatically during emergency
conditions or major disturbance of the AC system
• Additional DC power is calculated based on the frequency variation
/ swing of the connected AC system
• This function is provided for each pole at each station
STABILITY FUNCTIONS
Modes of Operation
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Modes of Operation
DC OH Line
Converter
Transformer
Thyristor
Valves
400 kV AC Bus
AC Filters,Reactors
Smoothing Reactor
Converter
Transformer
Thyristor
Valves
400 kV AC Bus
AC Filters, shuntcapacitors
Smoothing Reactor
Bipolar
Current
Current
Modes of Operation
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Modes of Operation
DC OH Line
Converter
Transformer
Thyristor
Valves
400 kV AC Bus
AC Filters,Reactors
Smoothing Reactor
Converter
Transformer
Thyristor
Valves
400 kV AC Bus
AC Filters
Smoothing Reactor
Monopolar Ground Return
Current
Modes of Operation
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Modes of Operation
DC OH Line
Converter
Transformer
Thyristor
Valves
400 kV AC Bus
AC Filters,Reactors
Smoothing Reactor
Converter
Transformer
Thyristor
Valves
400 kV AC Bus
AC Filters
Smoothing Reactor
Monopolar Metallic Return
Current
Basic Components of HVDC Terminal
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Converter Xmers
Valve Halls
-Thyristors
-Firing ckts
-Cooling ckt
Smoothing Reactor
Basic Components of HVDC Terminal
400 kV
DC Line
Control Room
-Control & Protection
-Telecommunication
AC PLC
AC Filter
DC Filter
SPS OF HVDC
kolar
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SPS OF HVDC kolar
Trip generation LOGIC
• Condition 1:• (500MW<Power loss ≤1000MW) & Pole Block = TRIP I
• Condition 2:• (1000MW<Power flow ≤1500MW) & Line fault & Pole Block =
TRIP I
• Condition 3:• (Power loss >1000MW) & Pole Block = TRIP II
• Condition 4:• (Power flow >1500MW) & Line fault & Pole Block = TRIP II
Whenever Trip II is generated, Trip I also generates
I/O
signals
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I/O signals
P 1
Power
Line fault
Deblock
Block
P 2
PLC
Block
Power
Deblock
Line fault
HVAC PLCC
Protection couplers
Fault Recorder
SER
Protection couplers"ESOF"
"ESOF"
DEFENCE MECHANISM FOR SR
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Load relief: TRIP I
Trip I
Chinakampalli
HosurSriperambudur
Selam
KolarChintamani
Hoody
Andhra Pradesh
150MW
Karnataka
Tamil Nadu
250MW
300MW
DEFENCE MECHANISM FOR SR
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Trip II
Gooty Anantapur
SomayajulapalliKurnool
TrichurKozhikode
Kannur
Somanahalli
Andhra Pradesh
200MW
Karnataka
Kerala
200MW
200MW
Load relief: TRIP II
MaduraiKaraikudiThiruvarur
TrichyIngur
Tamil Nadu
200MW
DC LINE FAULTS
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DC LINE FAULTS
• DC line faults detected by the DC protection based
on Wave front / under voltage protection
• Line fault recovery seq. initiated
• De-ionisation times
– 1st
– 200msec – 2nd – 250msec
– 3rd - 300msec at RVO
– After 300msec Pole block
• Line fault locator – distance accuracy upto one tower • On one pole trip – healthy Pole in GRM – 150MW
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IdL
Idee1
Idee2
IdE
UdN
IdN
IdHUdL
DC-Line
Electrode Line Electrode Line
IdH
Idee1
Idee2
IdE IdN
UdL
IdL
A B
Po er Re ersal on HVDC
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Power Reversal on HVDC
• Power reversal can only be initiated by the operator
SR ER• Pole needs to be Blocked before going for reverse
power operation
• Off-line power reversal can be performed in
monopolar or bipolar operation• In bipole power control mode the power direction is
changed on a bipolar basis
• Power reversal on a pole basis is provided in current
control mode
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