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Reactive Power Compensation - PTD H16M - Rev. 1.0 1

Tutorial on Static Var CompensatorsSan Francisco, June 12, 2005

Presented by:Heinz Tyll

Rajiv K. VarmaHubert Bilodeau

Chris Horwill

Prepared by:Hubert Bilodeau

Michael BahrmanChris Horwill

Peter LipsHeinz Tyll

Rajiv K. Varma


Tutorial on Static Var CompensatorsSan Francisco, June 12, 2005

OUTLINE

Module 1 - Reasons for reactive power compensation

Module 2 - Basic characteristics of SVC

Module 3 - SVC configurations and implications

Module 4 - Main components in existing installations

Module 5 - Thyristor valves

Module 6 - Regulation, Control and Protection system

Module 7 - Commissioning

Module 8 - Standards

Module 9 - References


Transmission Line CharacteristicsReceiving End Voltage during Power Transfer

Line constants: x’, r’, c’, g’VS VR

S=P+jQTransmission Line

Sending end Receiving end

PSIL = Surge impedance loadingExample: 200 km line with no lossesEffect of capacitive and inductive loading


Voltage Profile along a Long Transmission Line


Voltage Profile along a Long Transmission Line with Midpoint Reactive Power Compensation


Power System Improvements with Var Control:Influence of a Reactive Power Compensator


Voltage Stability

Normal System Conditions – 2000 MVA Short Circuit

n-1 Contingency – 1500 MVA Short Circuit Level

Voltage stability limits power transferAdequate stability margin required for contingenciesInadequate reactive power reserve risks voltage collapseDynamic voltage support via SVC permits higher power transfer


Increased Transfer with Dynamic Voltage Support

n-1 Contingency – 1500 MVA Short Circuit Level

Maximum power flow depends on network and voltage supportSteady state voltage via slow devices, e.g., switched capacitors, tap changersDynamic reactive power reserve required for contingencies Improved post-contingency voltage profile due to SVC dynamic reactive support


SVC Applications in LV Transmission Systems

Power factor correctionImprovement of load voltageDecrease of transmission system losses

to be added to power plant installationsto be added to operating costs

Load balancingSymmetrisation of system voltage


SVC Applications in HV Transmission Systems

Voltage controlImprovement of system voltage regulationunder varying load conditions

Increase in steady state power transfer capacity

Enhancement in transient stability

Prevention of voltage instability

Augmentation of system damping

Improvement of HVDC link performance


Voltage Control: Voltage in the Systemfor Various Operating Conditions

a Heavy load

b Light load

c Outage of 1 line(at full load)

d Load rejectionat bus 2

System Conditions:Load

SVC

230 kV - 300 km

V2V1

Grid

1.2

1.1

1.0

0.9

0.8

ba c d

without SVC

with SVCV2

V2N


Increase in Steady State Power Transfer Capacity: Comparison of different limits of power flow


The problems of distance & variable load

0 MW Ferranti Effect

400kV

Target 800MW Natural Load

1000MW System Collapse

400kV400kV

800MWGeneration

800MWLoad

400kV

Power

400kV

400kV Transmission Line (uncompensated)

Length of Line

800 km


The problems of distance & variable load

400kV400kV

1000MWGeneration

1000MWLoad

400kV

1000MW

400kV

SVCSVC

800 km

400kV

Target 1000MW Increased capacitydue to SVC

Shunt Compensated Line

Length of Line


Power Oscillation Damping (POD) with SVC

SVC

G1

P1, δ1Infinite bus

• If d(∆δ)/dt or ∆f is positive, i.e. rotor is accelerating due to built up kinetic energy, the FACTS device is controlled to increase generator electrical power output

• If d(∆δ)/dt or ∆f is negative, i.e. rotor is decelerating due to loss of kinetic energy, the FACTS device is controlled to decrease generator electrical power output

• Modulation of SVC bus voltage required through auxiliary signals


Two - Area study system (cont’d)

Three-phase fault is introduced in one of the transmission lines between bus 8 and bus 9

Oscillations caused:

• Local rotor mode oscillations• Inter- machine rotor mode oscillations• Inter- area oscillations are associated with swinging of

two machines in area 1 against the other two machinesin area 2.


Static Var Compensator (SVC)Damping of Power Oscillations (POD)


Improvement of HVDC Link Performance with SVC

Voltage regulation

Support during recovery from large disturbances

Suppression of temporary over voltages


Static Var Compensator (SVC)Typical SVC Configuration

LV bus bar

Fixed filter circuit

Thyristor controlledreactor

Thyristor switchedcapacitor

Control

Step-down transformer

HV

LV


Static Var Compensator (SVC)Common Configurations (1)

TCR, FC TSR, TSCTCR, TSC, FC


Static Var Compensator (SVC)Common Configurations (2)

3AC 60Hz 138 kV

SN = 150 MVA, uk = 10 %

CF1

3AC 60Hz 14.3 kV

STF 1

LF1

TCR 1

LTCR12

LTCR12

3AC 60Hz 14.3 kV

STF 2

LF2

TCR 2

LTCR22

LTCR22


Static Var Compensator (SVC)Loss Comparison

0.4


Main Components of an SVC

Transformer TSC FilterTCR


SVCs Centrals, NGC, UK 275 kV, 150 c / 75 i MVar


SVC Pelham, NGC, UK 400 kV, 150 c / 75 i MVar


Natal SVCs, Eskom, South AfricaDouble stacked air core reactor


SVC Brushy Hill, NSPC, CanadaFilter Branches


SVC Mead Adelanto, LADWP, USA Capacitor banks (externally fused)


Static Var Compensators (SVC) Filter Capacitor Bank (internally fused)


Thyristor Valve Cooling

IS

Major producers of heat losses are thyristors and snubber resistorsThyristor losses are determined by the forward voltage in the on state and the switching losses during turn on and turn offSnubber losses result from the charging current of the snubber capacitors


Thyristor Triggering & Monitoring Approaches

chec

k-ba

ck s

igna

l

optic

al tr

igge

r sig

nal

elec

tric

al g

ate

puls

e

ETT

Valve Base Electronic(valve control)with LED

TCU

check-backauxiliary power

logicelectric gate pulse

protective gate pulse

voltage detection

chec

k-ba

ck s

igna

l

optic

al g

ate

puls

e

Valve Base Electronic(valve control)with laser

LTT

voltage detection


Auxiliary Powerfor Triggering (Gating) of Thyristors

Typical gate pulse for ETT hasduration of 10 µspeak power of 50 W

Energy is extracted from power circuit at each level

Typical gate pulse for LTT hasduration of 10 µspeak power of 40 mW

Energy is provided by light pulse from ground level


LTT Light Path


Thyristor Valve Control and Monitoring

VALVE BASEELECTRONIC

I/O UNITS

MV SWITCHYARD

DIGITAL FAULTRECORDER

I/O UNITS

HV SWITCHYARD

I/O UNITS

TRANSFORMER

I/O UNITSCONTROL SYSTEM

MONITORINGPLANT CONTROL

CLOSED LOOPCONTROL

Industrial Ethernet

Process Fieldbus

AUXILIARYSUPPLY

I/O UNITS

COOLING SYSTEM

I/O UNITS

PROTECTIONSYSTEMI/O UNITS

DISPATCH CENTER

GATEWAYEXT. DEVICESV/Q CONTROL

PROTECTION(DIGSI, OSCOP, etc.)

WinCC REMOTE(HMI)

WinCC LOCAL(HMI)

TIMESYNCHRONISATION

GPS RECEIVER

SVC CONTROLROOM

SVC CONTROLROOM

SUBSTATIONCONTROL ROOM

SWITCHYARD

GPS

TSC/TCR


PLANT CONTROL

CLOSED LOOPCONTROL

WinCC LOCAL(HMI)

TSC/TCRVALVE

GPS

TIMESYNCHRONISATION

GPS RECEIVER

Process Fieldbus

Industrial Ethernet

SWITCHYARD

SVC CONTROLROOM



LTT Thyristor Module for SVC Valve

The module is a mechanical building block for the three phase valve setup


SVC Control, Monitoring and Protection

Station Control Hierarchies

Devices or High-Voltage Equipment in SwitchyardLocal control of devices or SVC ControlSubstation ControlDispatch Center Control



LOCAL (HMI)


I/O UNITS

MV SWITCHYARD

DIGITAL FAULTRECORDER

I/O UNITS

HV SWITCHYARD

I/O UNITS

TRANSFORMER

I/O UNITSCONTROL SYSTEM

MONITORINGPLANT CONTROL

CLOSED LOOPCONTROL

Industrial Ethernet

Process Fieldbus

AUXILIARYSUPPLY

I/O UNITS

COOLING SYSTEM

I/O UNITS

PROTECTIONSYSTEMI/O UNITS

DISPATCH CENTER

GATEWAYEXT. DEVICESV/Q CONTROL

PROTECTION

TIMESYNCHRONISATION

GPS RECEIVER

SVC CONTROLROOM

SVC CONTROLROOM


SWITCHYARD

GPS

TSC/TCR

REMOTE (HMI)



SVC Control

Plant control and monitoringClosed-loop control or RegulationValve Base ElectronicProtection system


Static Var Compensator (SVC)Plant control

SVC Station Control and Monitoring can be divided into:

Sequence control Operator's or Human Machine Interface (HMI))Local Area Communication (LAN)Time Synchronism and distributionsSequence of events and event recording (SER)Digital fault recorderI/O from switchyard



Typical functions of sequence control

SVC ON/OFF Sequence

Auto-Reclosing

Emergency Shutdown

Remote Control Function (that may include SCADA interface)

Manual and automatic switchyard control

Degraded control modes



The SVC can only be energized if the status of critical systems is confirmed such as:

Cooling System On-Line and no abnormal flow or temperature conditionsInterlocks in ready statePrimary voltage measurement system synchronized and readySwitches in closed positionCLC ready and synchronizedValve Firing System ready and valves blockedTransformer cooling normalPlant Control in proper configuration (local, remote etc.)Relay systems set and no lock-out functions detected


Static VAr Compensator (SVC)Voltage Control

Vsource

Znetwork

TCR TSCFC

LV

Control Regulator

XsSlope

+

-1/sTi-

SystemVoltage

Evaluation

HV

TSC Controller TCR/TSRController

POWER SYSTEM

VRESP

VREF

BSVC

BREF

VT

α

Distribution Unit

VBUS

∆V-

BSVC


Static Var Compensator (SVC)Additional control functions

POD control

Q control

Gain control

Stability control

Voltage symmetrisation


Static Var Compensator (SVC)Further Options

Degraded mode

Var management

Test mode

Redundancy


Control and RegulationControl loop Analysis

SVCNETSOURCERESPBUS IZVVV ×−==

The SVC control loop linking the regulator to the power system canbe represented as shown

Vsource

Znetwork

Control Regulator

XsSlope

+

-1/sTi-

SystemVoltage

Evaluation

HVPOWER SYSTEM

VRESP

VREF BREF

VT

VBUS

∆V-

Valve

Bsvc

BSVC

Slope Xs

V Primary

VSOURCE

VREF

Isvc

NetworkZnet

Vresp

BSVC

Vsource

Znetwork

Control Regulator

XsSlope

+

-1/sTi-

SystemVoltage

Evaluation

HVPOWER SYSTEM

VRESP

VREF BREF

VT

VBUS

∆V-

Valve

Bsvc

BSVC

Slope Xs

V Primary

VSOURCE

VREF

Isvc

NetworkZnet

Vresp

BSVC


Control and RegulationControl loop Analysis

Control Regulator

XsSlope

+

-1/sTi

VRESP

VREF

BREF

∆V

BSVC

ZNETWORK

Valvee -sTd

IsvcVsource-Vresp-

+

Vsource

Vresp-Vref

-

+

IsvcZnetVrespVsource ×=−


Module 7 Commissioning an SVC

The commissioning processPrecommissioning testsSystem and operational considerationsCommissioning testsStandards and guides


Basic steps in the commissioning process

Pre-commissioning testsTests on plant and sub systemsComplete before energising SVC at high voltage

Commissioning testsCorrect operation of the SVC designPerformance to specificationSVC performs correctly on the system

Acceptance by the purchaser


Precommissioning tests

Tests on individual items of plant to be done in an agreedwayInterNational Electrical Testing Association (NETA), www.netaworld.org

Produces documentation on test methods and record sheets (Acceptance Testing Specifications)Certifies testing companies and technicians

Equipment not covered by NETA documentation is tested to manufacturer’s own test sheets by the manufacturer



Purpose of pre-commissioning testsCheck that equipment is undamagedElectrical tests to confirm rating plate detailsChecks on installation

–Cabling–Connections–Insulation resistance

Functional checksGrounding resistance check



Tests to be done on the largest possible sub-systemswithout making equipment aliveTests to be witnessed by the purchaser’s representativewhere possibleComplete test results accepted by the purchaserTest results presented with a master document, listing all test sheets for each equipment

Proceed to the next stage


Safety

Safety rules covering live plantOSHA regulationsPurchaser’s safety rulesQualification of Vendor’s personnel


Effect on system

Test program to be agreed in advanceProgram should give details of each testTest program should state Mvar output for each testLimitations on SVC output during testing

Determined from studies by the purchaserLimits may vary with time of day or day of the weekGenerators may be dispatched during some tests


Operational matters

Personnel qualified to switchSwitching jurisdictionLiaison with control centerTest schedule to accompany the test program

Control center can plan system reconfiguration


Commissioning tests

Detailed test program containsStep by Step details for each testMeans of recording test resultsMvar outputs

Connect recording equipmentStage by stage testing


Commissioning tests Stage 1

Tests to confirm that the SVC has been designed correctlyEnergise all equipmentPass current in manual controlTest in automatic controlCooling plant checksHarmonic measurements


Commissioning tests Stage 2

Tests to confirm that the SVC has met the performance specification

System harmonic measurementsVoltage/current characteristicsSpeed of responseRFI measurementsAcoustic noise measurements


Commissioning tests stage 3

Tests to ensure that the SVC performs correctlyCapacitor and reactor switching testsAutomatic switchgear controlTemperature rise testsTrial operation periodOperation during disturbancesService experience


Service experience

Extension of commissioning testsMonitoring of service experience may last until the endof the warranty period

Commissioning test program does not normally includestaged faultsDFR and SER at the SVC installation used to gatherperformance data


Standards and Guides

IEEE 1303 : 1994. IEEE Guide for Static Var CompensatorField TestsCIGRE Document WG38-01 Task Force 2. Static Var Compensators, Chapter 6


SVC DesignFunctional Specification IEEE 1031

03_03 240203


SVC DesignField Tests for Static Var Compensator IEEE 1303

03_03 240203


SVC DesignTest Standard for thyristor valves IEC 61954

03_03 240203

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