Investigation of Small Signal StabilityInvestigationofSmallSignalStabilityforaRenewableEnergyBasedElectricityDistributionSystem

S Dahal N Mithulananthan T SahaS.Dahal,N.Mithulananthan,T.Saha

SchoolofInformationTechnologyandElectricalEngineeringTheUniversityofQueenslandSt.Lucia,QLD4072,Australia

Tuesday,July 27,2010

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IEEEPower&EnergySocietyGeneralMeeting,Minneapolis,USA

Presentation OutlinePresentation Outline

Background&Objective System Modelling & Small Signal StabilitySystemModelling&SmallSignalStabilityAnalysis

R l d Di i ResultsandDiscussions ConclusionsandFutureworks

2

BackgroundBackgroundGlobalIssues

Electricity Market Climate Change Limited ResourcesElectricityMarket ClimateChange LimitedResources

Distributed Renewable

s

Distributedgeneration

RenewableEnergy

o

m

e

CarbonCapture&Storage(CCS)

Nuclear

u

t

c

o

EfficiencyPluginHybridElectricVehicles(PHEV)

O

3

Distributed GenerationDistributedGeneration Usuallylessthan30MW(AEMO,Australia)

NeitherPlannednordispatchedcentrally(as of now)

Location Size(MW)

(asofnow)

1 0.0015to0.1

2 0.1to3

3 4 1 to 63,4 1to6

5,6,7 3to25

8 20andabove

4

Future Distribution SystemFutureDistributionSystem

Characteristics Challenges

DifferentGenerationTechnologies Stability,Control

BidirectionalPowerFlow Stability,Protection

Intermittency Dispatch,Regulation,Quality

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ObjectiveObjective

Tomodelthesystemforstabilityanalysis

i t d l f DG it t k & L d appropriatemodelsofDGunits,network&Load

Toanalysethesystemforsmallsignalstability

ImpactofwindandsolarImpactofpenetration

6

S M d lliSystemModelling&&

SmallSignalStabilityAnalysis

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Generator ModellingGeneratorModellingGenerator Stator Flux RotorFlux RotorInertia Exciter/ Converter/

Dynamics Dynamics Dynamics Governor Inverter

SynchronousGenerator

Generator

Squirrel CageInduction

InductionGenerator

DoublyFed InductionGenerator

Photovoltaic Generator

8

PV System ModelPVSystemModel

DClinkdynamics

dcpvdc PP

dtdvC =

2

2

Decoupledfromsystemdynamicsbyinverter.

9

Network ModellingNetworkModellingComponent ModelComponent Model

Network Admittancematrix

Generator CurrentSource

Loads Impedances

[ ] [ ][ ]VYI =

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Modal AnalysisModalAnalysis

DAE f tDAEsofpowersystems

),(.

yxfx =),(0),(

yxgyxfx

=

Participation factor

relatesthestatesandthemodes anelementofproductofrightandlefteigenvector

ikkiki vp =

11

Modal Analysis (Contd )ModalAnalysis(Contd..)Eigenvalue sensitivityEigenvaluesensitivity showsimpactofsystemparameters(K)oneigenvalue

movementmovement

Proposedsensitivityindex sensitivityofeigenvalue w.r.t.totalactivepower

iTi vP

A

fluctuation

iTi

ii

vP

PSI

. =

=

12

Results & DiscussionResults&Discussion

13

Case Distribution SystemCaseDistributionSystemSG2>5MW(PF Controlled)

SG1>4MW(voltage control)

ExternalGrid

(PFControlled)(voltagecontrol)

InductionGen>2MW System Load(Squirrelcage)

SystemLoad28MW,17MVAR

PVGen(1MW)

DGunitsareunscheduled

14

System EigenvaluesSystemEigenvalues20

25

EigenvalueContribution

10

15

20

Generator ModelOrder

Statevariables

SG1 6 6

-5

0

5

I

m

a

g

i

n

a

r

y

A

x

i

s

SG1 6 6

SG2 6 6

IG 3 3

-15

-10

5 IG 3 3

PV 0 0

T t l 15

-35 -30 -25 -20 -15 -10 -5 0-25

-20

Real Axis

Total 15

Eigenvalues 15

AlleigenvaluesinlefthalfofImaginaryaxis stablesystem

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Oscillatory ModesOscillatoryModes

Modes DampingRatio

Frequency(Hz)

DominantGenerator

1,2 0.26 3.28 PFControlled SG(Bus3)

3, 4 0.23 2.89 Voltage controlled SG (Bus 2)3,4 0.23 2.89 VoltagecontrolledSG(Bus2)

5,6 0.48 2.82 WindGenerator(Bus6)

Oscillatoryfrequenciesof3HzwereobservedWind generator contributes to highly damped modeWindgeneratorcontributestohighlydampedmode

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Penetration & ParticipationPenetration&ParticipationDominant generator

ModesDominantgenerator

Basecase 20%wind 20%solar

1,2 PFControlledSG PFControlledSG PFControlledSG

V l3,4 VoltagecontrolledSG WindGenerator

Voltage

controlledSGWind Generator/

5,6 WindGeneratorWindGenerator/Voltagecontrolled

SGWindGenerator

DominantgeneratorsmayalteraftersignificantpenetrationofwindWindgeneratorinfluencesmorethansolar

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Penetration & SensitivitiesPenetration&Sensitivities

Forincreasedsolarpenetration,sensitivitiesdecreaseforallmodes.

Forincreasedwindpenetration,sensitivitiesmaydecreaseorincrease.p y

Modesdominatedbysynchronousgeneratorsaremoresensitive.

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Time Domain AnalysisTimeDomainAnalysisThree phase fault applied for 70 ms at bus 15

1.004

1.006

Threephasefaultappliedfor70msatbus15.u

.

)

1

1.002Basecase

20%Windpe

e

d

(

p

.

u

0.996

0.99820%Wind

20%Solar

R

o

t

o

r

s

p

0.9940.8 1.3 1.8

R d d i i f l ll d SG b dTime(sec)

Windandsolarpenetrationimprovesdamping

RotorspeeddeviationofvoltagecontrolledSGwasobserved

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Time Domain Analysis (contd )TimeDomainAnalysis(contd.)

R d d i i f PF ll d SG b d

Windandsolarpenetrationhavenoimpactondamping

RotorspeeddeviationofPFcontrolledSGwasobserved

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Conclusions&FutureWorks

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ConclusionsConclusionsThedistributionsystemwithDGunitsexhibitoscillations.y

Frequenciesof3HzwereobservedSG modes are more sensitive than WG modesSGmodesaremoresensitivethanWGmodes

InformationonlocationofcontrollersParticipations are sensitive for wind than solar penetrationParticipationsaresensitiveforwindthansolarpenetration

rotorfluxvariablesofwindgeneratorsareinfluentialS l i d i i i i f i dSolarpenetrationdecreasessensitivitiesofeigenmodes

betterimpactonsmallsignalstabilityPenetrationofrenewablehasgoodimpact

betterdampingofvoltagecontrolledSG

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Future WorksFutureWorks

Loadmodelling

identificationandpropermodellingoftheloads

f llLocationanddesignofcontrollers

Performanceevaluationofthecontrollers

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ThankYouVeryMuch!!

Any Questions are welcomeAnyQuestionsarewelcome

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