HVDC KOLAR STATION.pdf

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



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



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



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

.



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



HVDC VALVE HALL LAYOUT



MULTIPLE VALVE UNIT

AC

DC

ValveQuadruplevalve

Arrester

AC

Grd

MultipleValve

Unit

D

YY



Circuit Diagram of the Converters for

Pole 1



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



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 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



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



Thyristor Module

SNUBBER CAPACITOR

SNUBBER RESISTOR

THYRISTOR

TE CARD

COOLING PIPE-PEX

GRADING CAPACITOR

FIBRE OPTICS



Thyristor Modular Unit top view



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



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



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



Capacitor Stack

ResistorReactorReactor

12/24 Double Tuned Filter – Sectional view

CT



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



Capacitor stack

ResistorReactor

C=23.759µF

Reactor

3/36 Double Tuned Filter – Sectional view

CT



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



DC Filter 12/24 TYPE

C1=1800 nF

R1=400ΩL1=14.71 mH

L2=8.19 mH

C1=5700 nF



DC Filter 12/36 TYPE

C1=1800 nF

R1=400ΩL1=7.21 mH

L2=12.68mH

C1=3300 nF



STABILITY FUNCTIONS



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



– 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



– 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



– 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



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



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



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



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



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



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



Load relief: TRIP I

Trip I

Chinakampalli

HosurSriperambudur

Selam

KolarChintamani

Hoody

Andhra Pradesh

150MW

Karnataka

Tamil Nadu

250MW

300MW

DEFENCE MECHANISM FOR SR



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



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



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



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

HVDC KOLAR STATION.pdf

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