9 Future Power Systems PAOLONE

8/12/2019 9 Future Power Systems PAOLONE

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Impactoflightningonthereliability

offuturepowersystems

Prof.Mario

Paolone

DESL DistributedElectricalSystemslaboratorycolePolytechniqueFdraledeLausanne

Lightning:detectionandprotectionETH,Zrich

Oct.14th,2011


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Outline

Introduction

Lightningperformanceofdistributionnetworks

LightningimpactonHVDCoverheadtransmissionlines

Conclusions


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Outline

Introduction



Conclusions


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Introduction

Themissionofmodernandfuturepowersystemsistosupplyelectricenergysatisfyingconflictingrequirements:

reliabilityandsecurityofsupply;Economy/rationaluseofenergyenvironmental

protection

Massiveintroductionofrenewablesatvariousvoltagelevels.


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Introduction

RenewableElectricityGeneratingCapacityWorldwide

Source:U.S.Dept.ofEnergy,RenewableEnergyDataBook,August 2010


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Introduction

RenewableElectricityGeneratingCapacityWorldwide

Source:U.S.Dept.ofEnergy,RenewableEnergyDataBook,August 2010

Globalrenewableelectricityinstallations(excluding

hydropower)havemorethantripledfrom20002009.

Windandsolarenergyarethefastestgrowingrenewableenergytechnologiesworldwide.WindandsolarPVgenerationgrewbyafactor

of

more

than

14

between2000and2009.

In

2009,

Germany

led

the

world

in

cumulative

solar

PV

installedcapacity.TheUnitedStatesleadstheworldinwind,geothermal,biomass,andCSPinstalledcapacity.


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Introduction

2010 Population density (prs/km2)Wind speed (annual avg m/s)

Remark:mismatchbetweenrenewableslocationanddemand


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Introduction

2010 Population density (prs/km2)Daily solar irradiation (annual avg Wh/m2

)

Remark:mismatchbetweenrenewableslocationanddemand


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Introduction

Impactofrenewablesontransmissionnetworks:increaseoftransmissioncapacityoverlongdistances

Example:

required

number

of

lines

in

parallel

to

transmit 6

GWHVDC

EHVandUHVACtransmissionlines

+ straightforward integration+ reliability+ investments- stability- voltage control

- complexity in power flow control

+ power flows control

+ transfer capacity+ stability- reliability on long term


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Introduction

Impactofrenewablesontransmissionnetworks:HVDC

Source:J.A.Fleeman*,P.E.,R.Gutman,P.E.,M.Heyeck,M.Bahrman,B.Normark,EHVACandHVDCTransmission

WorkingTogethertoIntegrateRenewablePower,CigrIntegrationofWideScaleRenewableResourcesintothePowerDeliverySystem,Calgary,Canada.29 31July2009

USAfutureACEHVandHVDCinstallations

Europe

futureHVDCinstallations


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Introduction

ImpactofembeddedgenerationondistributionnetworkstheItalianexample Primarysubstationminimumpower

16%oftheItalianprimarysubstationsexperiencepowerflowinversionstothesubtransmissionnetwork(courtesyofENEL,Italy)

MajorissuesVoltagecontrol

Securenetworkoperationafter

transientssubsequent

to

the

loss

ofmajordispersedgenerationandsubsequentreconnection

Protectionsandshortcircuit

levelsDetectionandoperationinislandingconditions


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Introduction

Remarks

Transmissionanddistributionnetworksreliabilityisacrucialelementfortheintegrationofrenewables

Revampingoftopicsrelatedtoinsulationcoordinationofbothtransmissionanddistributionlines

Example Cigr SC4,Systemtechnicalperformances

Lightning

protection

and

insulation

coordination,

their

modelingandanalysiswithchangingtechnologies(windturbines,UHVlines,activedistributionnetworks).


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Outline

Introduction



Conclusions


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Lightningperformanceofdistribution

networks

2

4

6

8

10

12

14

0 2 4 6 8

Lightning Flash Density (flash / km2 / year)

Sags/m

onth/bus

Source:E.W.GuntherandH.Metha,Asurveyofdistributionsystempowerquality,IEEETPWD,101,1995

Impactoflightningonthepowerqualityofdistributionnetworks


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networks

htl

hdl

Overhead transmission lines Overhead distribution lines

Remark: the different geometry and insulation characteristics of transmissionand distribution overhead lines direct or indirect lightning events differentlyconcern the two line types:

htl>>hdlCFOtl>>CFOdl

direct lightning major concern for transmission lines

indirect lightning major concern for distribution lines


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networksTheevaluationofthelightningperformanceofoverheaddistributionlines,availablestandards:

IEEEStd.Guide1410;JointCigrCiredWGC4.4.02;

Inherentcomplexityofdistributionsystems:numberoflines(mainfeederwithlaterals)presenceofpowercomponents(transformers,surge

arresters,groundings,etc.)iswellfarfromthestraightlineconfigurationgenerallyadoptedintheliteratureandintheabovestandards.


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networks

Num

berofinducedv

oltageswithmag

nitude

exceedingthevalue

inabscissa/100km/yr

Voltage [kV]

LIGHTNING PERFORMANCE

OF A DISTRIBUTION LINEDistribution systems

insulation coordination

Evaluation of the number ofannual flashovers due to

indirect lightning that adistribution overhead linemay experience, as afunction of insulation level

and line constructiondesign.

CFO [kV]

Numberof

Flashovers

Note: a so called incidence model is needed

To distinghish between direct and indirect


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networks

maxZ

0I

0h

y1

1

2

v

c

1

11

2

v

c

2

Ruscksimplifiedformula

Z01/ 4

0 / o 30

Assumptions:

a. singleconductor

b. infinitelylonglinesabovea

c. perfectlycond.ground

d. stepcurrentwaveshape

v returnstrokevelocity

'1

2

sw sw c

sw g

h ZU

U h Z R

Toosimple:notadequate

inmanycases!

Toosimple:notadequate

inmanycases!

What was available within IEEE Std. 1410-2004 ?


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networksWhat is available within the new IEEE Std. 1410-2010 ?

Lightning return stroke current modelRSC i(z,t)

Lightning ElectroMagnetic Pulse Model

i(z,t) LEMP E, B

ElectroMagnetic Coupling Model

E, B EMC

i(0,t)

U(x,t)

I(x,t)


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networksWhat is available within the new IEEE Std. 1410-2010 ?

Source: A. Borghetti, C. A. Nucci, M. Paolone, An improved procedure for the assessment of overhead line indirect lightningperformance and its comparison with the IEEE Std. 1410 method, IEEE Trans. on Power Delivery, pp. 684-692, January 2007.

Single

conductor

lineSingle

conductor

line


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networks

Singleconductorline

plus

grounded

conductor

Singleconductorlineplusgroundedconductor

Influenceofgroundings spacing

Source: A. Borghetti, C. A. Nucci, M. Paolone, An improved procedure for the assessment of overhead line indirect lightningperformance and its comparison with the IEEE Std. 1410 method, IEEE Trans. on Power Delivery, pp. 684-692, January 2007.


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ZcZc500 m

Strokelocation

50m

370 m

SWgr. point

SWgr. point

SW

gr. point

Ideal ground, Rg=0


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networksInfluenceofgroundings ideal/lossyground

Comparison between phase-to-ground and phase-to-grounded-wire flashover ratecurves calculated for different ground conductivity g and grounding resistance Rg.

(Shielding wire grounded each 200 m. A linear model is assumed for the grounding impedance ofthe neutral or shielding wire )

Comparison between phase-to-ground and phase-to-grounded-wire flashover ratecurves calculated for different ground conductivity g and grounding resistance Rg.

(Shielding wire grounded each 200 m. A linear model is assumed for the grounding impedance ofthe neutral or shielding wire )

2.2

0.52

Singleconductorline

plus

grounded

conductor

Singleconductorlineplusgroundedconductor


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networks

10.8m

a

b

c

1.3 m

10m

CFO=125kVCoord inate Gauss-Boaga x [km]

Coo

rdinateGauss-Boa

gay[km]

5080

5082

5084

5086

5088

5090

5092

2345 2347 2349 2351 2353 2355

Influenceofnetworktopology


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networksInfluenceofnetworktopologyExperimentalobservations

2345 2346 2347 2348 2349 2350 2351 2352 2353 2354 2355 23565081

5082

5083

5084

5085

5086

5087

5088

5089

5090

5091

5092

Venus

Torrate

Maglio

Primary 132/20 kVsubstation ' Ponterosso'

Coordinate Gauss-Boaga x (km)

CoordinateGauss-Boaga

y(km)

fl.num:30260#4 del 30/8/2007 11:23:36.407205945 -48.4 kA

CESISIRFeventn.302604Aug.30,2007Ip= 48.4kA


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networks

0.0001

0.0010

0.0100

0.1000

1.0000

50 100 150 200 250

Voltage [kV]

Annualnumberofeventsex

ceedingthevalue

in

abscissa

straight line

H-shaped network (type 1)H-shaped network (type 2)

T-shaped network

Influenceofnetworktopology


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Outline

Introduction



Conclusions

Li h i i HVDC h d


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LightningimpactonHVDCoverhead

transmission

linesHVDCtypicalconfiguration

Li ht i i t HVDC h d


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transmission

linesThedesignerofapowersystemneedstoknowtheflashoverrateofanoverheadpowerlineforaselectedinsulationleveltomeetthereliabilitycriteriasetforthesystem.

Thelightningflashoverrate(lightningperformanceoftheline)isthesumof:directstrikesflashoverrate;nearbystrikesflashoverrate(disregardedinviewofTLCFO);

flashoverratefromfailuresofprotectiveequipment.Onlyfirststrokesofnegativedownwardflashesaregenerallytakenintoaccountinlightningperformancestudies.

Topredictthelightningperformanceoneneedstheknowledgeof:thelightningactivity(thegroundflashdensityNg(fl/km2/yr));theexposuretolightning;lightningconsequences.



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transmission

linesExposure(i.e.lightningincidence)

Themodelsappliedtocalculatelightningincidenceontransmission

lines

are

based

on

consideration

of

the

physical

processes

involved

duringthefinalstagesofprogressionofachargeddownwardlightningleader(usuallyassumednegative)initsapproachtotheearth,ortowardstructuressuchasalineortransmissiontower.

Thesemodels,basedondownwardleaderapproach,couldbedividedinto:

conventionalmodels

electrogeometric

model;

morerecentmodels leaderprogressionmodel(LPM).



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transmission

lines

rc

rg

nearbystroke

directstroke

h dl

rc:strikingdistancestoaphaseconductor;

rg:strikingdistancestoground;

dl:lateralattractivedistanceoftheline

Singleconductoroverheadlineofagivenheighth:

22 hrrd gcl

rc rg

A b k

Armstrong andWhitehead

6.7 0.8 0.9

IEEE WG 10 0.65 0.55

cg rkr b

rg IAr g

b

rc IAr c

Conventionalelectrogeometricmodel:basicconcept

Lightning impact on HVDC overhead


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transmission

linesAdvanced models: leader progression modelSequential solution of the Poissons equation: )( 0 PV

Electric

potential

iso

surfaces

associatedtoadownwardleadercorrespondingtoapeakcurrentof20kA.Downwardleaderat360mfromtheground.Inceptionconditionsforthe

formationof

the

upward

leader

fromtheearthedstructurehavenotyetbeenreached.



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transmissionlines

Lightningleaderapproachingground:downwardmotionunperturbed unlesscriticalfieldconditionsdevelopjuncturewiththenearbytower,calledfinaljump.

Foreachelectricfieldstreamlineconnectingthetwo

leadersithasdeterminedwhethertheelectricfield

exceedsthevalueof500 kV/malongtheoverallstreamline

length.

Peakcurrentof20kAlocatedat23mfromthe30mhighearthedstructure:electricfieldisosurfacesandstreamlines.



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transmissionlines

Shieldingfailure:basicconcept

Foraspecificvalueofstrokecurrent,arcsofradiircaredrawnfromthephaseconductorsandfromtheshieldwireswiththehorizontallineatadistancergfromtheearth.Ashieldingfailure

isastrokethatterminatesonaphaseconductor,inspiteofthepresenceofoverheadgroundwires.Theflashcollectionrateis:

min

)()]()([2

I

cggs dIIfIDIDLNN

max

min2

I

Icg dIIfDLNSFR

Integratingonlytheexposureareaofthephaseconductors,weobtaintheshieldingfailurerate(SFR)

rg

rc

rc

Dc Dg

Where: Iministheminimumlightningcurrent(2or3kA); Imaxisthemaximumcurrentatandabovewhich

no

stroke

will

terminate

on

the

phase

conductor.



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transmissionlines

Shieldingfailureflashoverrate:SFFOR

IfthevoltageEissettotheCFO,negativepolarity,

thenthecriticalcurrent

Ic,atandabovewhich

flashoveroccurs.TheinitialconditionoftheHVDCcouldbetakenintoaccountintotheestimationofI

c.

ThereforeSFFORis:

SFFOR 2NgL Dcf I dIIc

Imax



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transmissionlines

ShieldingfailureonHVDC:experimentalobservations

Source: Hengxin He, Junjia He, Zhang, D., Li Ding, Zhenglong Jiang, Cheng Wang, Huisheng Ye, Experimental Study on Lighting ShieldingPerformance of 500 kV HVDC Transmission Lines, 2009 Asia-Pacific Power and Energy Engineering Conference (APPEEC 2009).



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transmissionlines





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transmissionlines

Remark: it seems that the applied DC voltage on the polar conductor, as well as itspolarity, plays a role into the upward streamer inception criterion and, therefore, into theattachment process.





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transmissionlines

Backflashover:basicconcepts

Whenlightningstrikesthetower(ortheOHGWs),thecurrent

on

the

tower

and

ground

impedances

causes

the

rise

of

the

towervoltage.Asmallfractionofthetowerandshieldwiresvoltageisinducedinthephaseconductorsduetotheelectromagneticcoupling,neverthelessthetowerandshieldwiresvoltagebecomesgreaterthenphaseconductorsvoltage.

IfthevoltageexceedsthelineCFO,flashoveroccurscalledbackflashorbackflashoverandthecorrespondingminimumlightningcurrentthatproducessuchaflashoveriscalledcriticalcurrent.

Thetermback referstothefactthatthehighestvoltageisonapartofthepowersystemnormallyatgroundpotential.



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transmissionlines

Estimationofthebackflashrate

UseoftheElectromagneticTransientProgram

The

calculation

of

the

critical

current

Icby

means

of

EMTP

like

programs

allowstotakeinaccount:

waveshapeofthecurrentsource;

flashovercriteriaintheformofvolttimecharacteristics;

transmission

line

models

including

all

line

conductors

(em

coupling); representationofthesoilionization;

frequencydependentgroundingmodels;

surgearresters;

representationofallthepowersystemcomponents;ForHVDC:

conductorspotential(prelightningDCvoltagestatus);

frequencydependencyofinputimpedanceofHVDCpowerelectronics.

ForHVDC:

conductorspotential(prelightningDCvoltagestatus);

frequencydependencyofinputimpedanceofHVDCpowerelectronics.



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transmissionlines

BFR 0.6NL f Itf

f tf

Ic

0

dIdtf fl100km yr

Calculationofthebackflashoverrate(BFR)TheBFRistheprobabilityofexceedingthecriticalcurrentmultipliedbythenumberofflashestothelineNL.However,sincethecrestvoltageandtheCFOarebothfunctions

of

the

time

to

crest

tfofthelightningcurrent,thecriticalcurrent

previouslydeterminedisvariable.Therefore,theBFRconsideringallthepossible

timetocrestvaluesis:

Where

f(I/tf)

is

the

conditional

probability

density

function

of

the

stroke

current

given

thetimetocrestandf(tf)istheprobabilityfunctionofthetimetocrest.

Note:inordertoobtaintheBFRforstrokestothetowerandstrokeandtothespans,theBFRobtainedforstrokestothetowerismultipliedbyacoefficient,equalto0.6[Hileman,1999]

O li


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Outline

Introduction



Conclusions

C l i


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Conclusions

Renewablesintegrationisincreasingtheneedofelectricalnetworkreliability revampingof thestudiesoninsulationcoordinationofT&Dsystems.

Distribution:advancedmodelsintegratedintointernationalstandardfortheevaluationoflightningperformancetakingintoaccountrealisticnetwork

configurations. TransmissionwithHVDC:inherentcharacteristics

influencethelightningperformance needofmore

research

on attachmentprocessandrelevantanalytical

formulation; highfrequencymodelsforlineterminations.

9 Future Power Systems PAOLONE

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