design requirements hvdc - usaid sari/energy...

Design Of HVDC System

23.08.2011 ET-PS Energy Transmission

Objectives for Design Of HVDC SystemSystem

Maximum reliability / availability y y High Flexibility. Low Maintenance Safety


System Consideration for Design Of HVDC SystemHVDC System

Outage risks for planning High capacity Links.g p g g p y Inter-tripping Schemes to take care of HVDC pole/Bipole

outages. Minimum and Maximum Fault levels. Reactive Power Exchange with System.

N d f E t l D i t Need for External Dynamic support. Load rejection Over voltages (TOV). Recovery from AC and DC faults Recovery from AC and DC faults. Commutation failure performance.


COMMUNICATIONCOMMUNICATION

Highly reliable and effective telecommunication systemshould be available between the terminals.

Telecommunication link can be either PLCC or OPGWTelecommunication link can be either PLCC or OPGW.

Optical Ground Wire (OPGW) can be installed on one ofth k f th HVDC lithe peaks of the HVDC line.


System SpecificationSystem Specification

Configuration

Main Power Requirements and modes of operation

System Parameters and main requirements

VoltageVoltageFrequencyHarmonic ImpedanceReactive Power ExchangeReactive Power ExchangeShort Circuit LevelEnvironmental Conditions – temp, soil, location etc.


AC SYSTEM CONFIGURATIONAC SYSTEM CONFIGURATION

AC system 400kV; The HVDC system shall be designed yvoltage

; y gfor voltages from 360 to 440kV but the performance shall be guaranteed for voltages from 380 to 420 kVfrom 380 to 420 kV

Frequency 50Hz; The HVDC system shall be designed for frequencies ranging from 47.5 Hz to 52.5 g gHz but the performance shall be guaranteed for frequencies from 48.5 Hz to 51.5 Hz

Short Circuit Levels

Ranges to be given for both rectifier and inverter side.


Levels

Single Line Diagram for a Bipolar Transmission SystemTransmission System

AC SystemAC System HVDC Station DC Overhead Line HVDC Station


Single Line Diagram for a Back-to-Back SystemBack System

AC S t HVDC St ti ACAC System HVDC Station AC System


Bipolar HVDC TerminalBipolar HVDC Terminal

ACSystem 1 System 2

ACACACAC

1 AC Switchyard

2 AC Filters

Controls, Protection, MonitoringTo/ fromotherterminal

3 Transformers

4 Converter Valves

Pole 1

ACfilter

DCfilter

5 Smoothing Reactorsand DC Filters

6 DC Switchyard

Pole 2

6611 22 33 44 55

DCfilter


Basic Design ProcessBasic Design Process

S p e c i f i c a t i o nS p e c i f i c a t i o n Main transmission Data

Pdc Udc Idc etc.AC-Network Load flow study

St bilit t d

Simulator Computer

Stability studyMain data of converter station (U, I, , Q)

DC H i AC Harmonics

Insulationcoordination Thyristor

Simulation study

DC FiltersSmoothingDC Li AC-Filters Converter

DC-Harmonics AC-Harmonics

coordinationand arresters

yvalves

DC-Filtersgreactor DC-Line AC Filters Converter

transformer


Design data for all equipment of the HVDC-system

Main Data of Converter Station

Basic Control ConceptBasic Control ConceptDC-Voltage, DC-Current, ...

Thyristor TypeShort Circuit Current Capability

Main DataDC Voltage V and DC Current IDC Voltage Vdc and DC Current Idc

Reactive Power QFiring Angles AC B V lt (T Ch )


AC-Bus Voltage (Tap Changers)

Main design parametersMain design parameters

P t T l h K lParameter Talcher Kolar

Min AC Voltage (normal/extreme) 380/360kV 380/360kV

Max AC Voltage (normal/extreme) 420/440kV 420/440kV

Min Frequency(normal/extreme) 48.5/47.5Hz 48.5/47.5Hz

Max Frequency(normal/extreme) 50.5/52.5Hz 50.5/52.5Hz

Min SCR for Pdc > 1000 MW 2.5 2.5

Min SCR for 500 MW < Pdc < 1000 MW

3 3

Mi SCR f Pd < 500 MW 1500 1500


Min SCR for Pdc < 500 MW 1500 1500

Salient FeaturesSalient Features

Rectifier Talcher, OrissaI t K l K t kInverter Kolar, KarnatakaDistance 1400 kmRated Power 2000 MWOperating Voltage 500 kV DCReduced Voltage 400 kV DCOverloadTwo Hour, 50C 1.1 pu per poleTwo Hour, 33C 1.2 pu per poleHalf an hour 50/33C 1 2/1 3 pu per poleHalf an hour, 50/33 C 1.2/1.3 pu per poleFive Seconds 1.47 pu per pole


Reactive Power of HVDC ConverterReactive Power of HVDC Converter

600

400

500

Q [MVAr]

Q rect.

200

300

Q filter

0

100delta Q

+80

-200

-100

0 0 2 0 4 0 6 0 8 1 1 2 1 4

-80


power in p.u.0 0,2 0,4 0,6 0,8 1 1,2 1,4

Reactive PowerReactive Power

R ti t ll t t t ti l lReactive power controller operates at station level

Reactive power requirements are met byAC h i filAC harmonic filtersCapacitor banks and reactors

Sizing of RP elements is influenced by

The reactive power exchange capabilities of the ac system at given dc power levelReactive power consumption of converter at given dc

power level


… contd

Reactive PowerReactive Power

Various sub-banks can be connected either in automatic or manual modeTwo closed loop automatic control modes are possibleAC Voltage controlReactive power exchange controlSwitching hierarchy isSwitching hierarchy isAC voltageHarmonic performanceHarmonic performanceReactive power exchange

…contd


AC FiltersAC Filters

C l l ti M th dCalculation Method

Step 1 Calculate AC Harmonics,S l t M i l V l

Step 2 Calculate AC SystemImpedance (Locus)

pSelect Maximal Values

Step 3 Split up Reactive Power,Define Filter Parameters

Step 4 Check Filter Performance

Step 5Calculate Filter Performanceand Component Stresses forDifferent Load Conditions

p


AC Filter PerformanceAC Filter Performance

Dn individual Distortion = 100[%]1

UnU

Dtot total Distortion = 50 2n=2 nD

TIF Telephone Interference Factor

THFF Telephone Harmonic Form Factor


AC Harmonic CurrentsAC Harmonic Currents

dc current (Id/IdN) dc voltage (Du/UdN)( )

1.0

0.5

0.0

-0.5

5 10 15 20

0.0 -1.05 10 15 20

t (ms)current [%]

t (ms)

100

1

10

1 2 3 4 5 6 7 8 9 10 11 13 23 25 35 37 47 49

1

0.1

0.01


1 2 3 4 5 6 7 8 9 10 11 13 23 25 35 37 47 49order of harmonic

Design Aspects - Insulation DesignDesign Aspects Insulation Design

I n s u l a t i o n C o o r d i n a t i o n

A i r C l e a r a n c e &F l h D i tF l a s h o v e r D i s t a n c e

C r e e p a g e D i s t a n c e


Design Aspects- Insulation DesignDesign Aspects Insulation Design

Air Clearance / Flashover DistanceAir Clearance / Flashover Distance C l e a r a n c e s / F l a s h D i s t a n c e s i n H V D C S t a t i o n s

are determined based on impulse overvoltages,normally of the switching impulse type

E l e c t r o d e S h a p e s o f t h e E q u i p m e n t

are important; favorable electrode shapes (especially indoors) allow to reduce clearances / flash distances, compared to commonly used design based on a rod-planeconfiguration


configuration

Design Aspects - Insulation DesignDesign Aspects Insulation Design

Creepage DistanceCreepage Distance Indoors (Valve Hall)

l d d i tclean and dry environment

typical values: 1.2 ~ 1.4 cm/kV

O u t d o o r s

decisive influences:degree of pollutionmaterial / surface of equipmentdecisive influences:

Typical values for largedi t

material / surface of equipmentdiameter of equipment

4 cm/kV (normal pollution) 5 cm/kV (heavier pollution)


diameters: 5 cm/kV (heavier pollution)up to 6 cm/kV (Bushings, porcelain)

Insulation Co-ordination with ZnO-ArrestersArresters

Arrester Protection Level and Energy CapabilityArrester Protection Level and Energy Capability

Step 1 Define Arrester Rating for Maximum

Step 2

Calculate Protection Levels forSwitching Surges (Lightning)Dynamic Overvoltages

Step 1Continuous Operating Voltage (MCOV)

Check Energy CapabilityIf Energy Capability exceeded,

Dynamic Overvoltages Fault Conditions

Step 3 increase MCOV or increase Number of Parallel Columns and repeat Calculation


Insulation Co-ordination with ZnO-ArrestersInsulation Co-ordination with ZnO-Arresters

Arrester Arrangement

AC-Bus Arrester

Valve Unit Arrester

Valve Group Arrester

DC Line Arrester

Neutral Bus Arrester

Filter Arrester


Arrester ArrangementArrester Arrangement

AC-Filter Bus

C1 1ArrB1

8 9

ArrD

Lsmooth

DC Line

C1 13

L1AC-Bus 2

B1

ArrB2

7

6 Arr

D

F FL14Fachv

L2

ArrA

ArrB2

Arr

6

5

C Fdc Fdc

FacIv

C2ArrB2

10 11

ArrE1

ArrE2

neutral

AC-Filter


Energy Unavailability

Energy unavailability is a measure of the energy which could not have been transmitted due to (scheduled & forced)not have been transmitted due to (scheduled & forced) outages.

E U il bilit % (EU) EOH/PH 100Energy Unavailability % (EU) = EOH/PH x 100

Forced Energy Unavailability % (FEU) = EFOH/PH x 100

Scheduled Energy Unavailability % (SEU) = ESOH/PH x 100


Energy AvailabilityEnergy Availability

A measure of the energy which could have been transmitted except for limitations of capacity due to outages, arising from any cause, either forced or scheduled.

Energy Availability % (EA) = (100 - EU)


ReliabilityReliability

Reliability is expressed in terms of the number of forced outages of curtailment occurrences of poles and Bipole per unit of time, usually one year.

EOF is the equivalent outage frequency which shall be calculated as follows:

EOF = number of one pole outages x 1+ number of other pole outages x 1+ number of bipole outages x 2


Normally specified ValuesNormally specified Values

Energy Availability: 97%

FEU: 0.7 %

Reliability: Not more than 10 forced outages


Outage StatisticsOutage Statistics


HVDC Station Losses

Losses calculated as per IEC-61803

No load losses and load losses are guaranteed


THANK YOU


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