7/31/2019 AA WindModel
1/99
Arnold SchwarzeneggerGovernor
REVIEW OF INTERNATIONALEXPERIENCE INTEGRATING VARIABLE
RENEWABLE ENERGY GENERATION
Prepared For:
California Energy CommissionPublic Interest Energy Research Program
PIERP
ROJECTREPORT
Prepared By:EXETER
ASSOCIATES, INCApril 2007CEC-500-2007-029
7/31/2019 AA WindModel
2/99
Prepared By:
Exeter Associates, Inc.Kevin PorterColumbia, MarylandCommission Contract No. 500-02-004Commission Work Authorization No: MR-017
Prepared For:Public Interest Energy Research (PIER) Program
California Energy Commission
Michael Kane, Dora Yen-Nakafuji, Ph.D.
Contract Manager
Dora Yen-Nakafuji, Ph.D.
Project Manager
Elaine Sison-Lebrilla, P.E.
Manager
Energy Generation Research Office
Martha Krebs, Ph.D.
Deputy Director
ENERGY RESEARCH & DEVELOPMENTDIVISION
B.B. Blevins
Executive Director
DISCLAIMERThis report was prepared as the result of work sponsored by the California Energy Commission. It does not necessarily representthe views of the Energy Commission, its employees or the State of California. The Energy Commission, the State of California, itsemployees, contractors and subcontractors make no warrant, express or implied, and assume no legal liability for the informationin this report; nor does any party represent that the uses of this information will not infringe upon privately owned rights. Thisreport has not been approved or disapproved by the California Energy Commission nor has the California Energy Commissionpassed upon the accuracy or adequacy of the information in this report.
7/31/2019 AA WindModel
3/99
i
Acknowledgments
TheCaliforniaEnergyCommissionsPublicInterestEnergyResearchprogramfundedthework
describedinthereport.TheauthorsthankDoraYenNakafujiandtheCaliforniaWindEnergy
Collaborativeteamfortheirtechnicalsupport.TheauthorsalsothankThomasAckermanofthe
RoyalInstitute
of
Technology
in
Sweden;
Brendan
Kirby
of
Oak
Ridge
National
Laboratory;
BrianParsonsandMichaelMilliganoftheNationalRenewableEnergyLaboratory;Jim
BlatchfordandDavidHawkinsoftheCaliforniaIndependentSystemOperator;J.CharlesSmith
oftheUtilityWindIntegrationGroup;HanneleHolttinenoftheVTTTechnicalResearchCenter
inFinland;BernhardErnstoftheRheinischWestflischesElektrizittswerkAktiengesellschaft
(RWE)TransmissionSystemOperatorinGermany;AlbertoCenaofAsociacinEmpresarial
Elica(AEE)inSpain;LucyCraigofGarradHassaninSpain;DaveOlsenofWestWindWires;
MarkAhlstromofWindLogicsInc.;TomMillerofPacificGasandElectric;AbrahamEllisof
PublicServiceCompanyofNewMexico;andJohnKehleroftheAlbertaElectricSystem
Operatorforansweringnumerousquestionsandprovidingusefulinsights.Anyremaining
errors
or
omissions
are
our
own.
Pleasecitethisreportasfollows:
KevinPorter,ChristinaMuddandMichelleWeisburger.2007.ReviewofInternationalExperience
IntegratingVariableRenewableEnergyGeneration.CaliforniaEnergyCommission,PIER
RenewableEnergyTechnologiesProgram.CEC5002007029.
7/31/2019 AA WindModel
4/99
ii
Preface
ThePublicInterestEnergyResearch(PIER)Programsupportspublicinterestenergyresearch
anddevelopmentthatwillhelpimprovethequalityoflifeinCaliforniabybringing
environmentallysafe,affordable,andreliableenergyservicesandproductstothemarketplace.
ThePIERProgram,managedbytheCaliforniaEnergyCommission(EnergyCommission),
conductspublicinterestresearch,development,anddemonstration(RD&D)projectstobenefit
theelectricityandnaturalgasratepayersinCalifornia.
ThePIERprogramstrivestoconductthemostpromisingpublicinterestenergyresearchby
partneringwithRD&Dorganizations,includingindividuals,businesses,utilities,andpublicor
privateresearchinstitutions.
PIERfundingeffortsarefocusedonthefollowingRD&Dprogramareas:
BuildingsEndUseEnergyEfficiency
EnergyInnovations
Small
Grants
EnergyRelatedEnvironmentalResearch
EnergySystemsIntegration
EnvironmentallyPreferredAdvancedGeneration
Industrial/Agricultural/WaterEndUseEnergyEfficiency
RenewableEnergyTechnologies
Transportation
ReviewofInternationalExperienceIntegratingVariableRenewableEnergyGenerationisthefinal
reportfor
asubtask
of
Task
3for
the
PIER
Intermittency
Analysis
Project
(IAP),
contract
number50002004,workauthorizationnumberMR017,conductedbytheIAPteamcomprised
oftheCaliforniaWindEnergyCollaborative,ExeterAssociates,BEWEngineering,DavisPower
Consulting,andGEEnergyConsulting(withassistancefromAWSTruewind,National
RenewableEnergyLaboratory(NREL),OakRidgeNationalLaboratory(ORNL),andRumla
Consulting).TheinformationfromthisprojectcontributestoPIERsRenewableEnergy
Technologiesprogram.
FormoreinformationonthePIERProgram,pleasevisittheEnergyCommissionswebsiteat
www.energy.ca.gov/pierorcontacttheEnergyCommissionat(916)6545164.
7/31/2019 AA WindModel
5/99
iii
Table of ContentsAcknowledgements .................................................................................................................................... i
Preface..........................................................................................................................................................ii
ListofTables...............................................................................................................................................v
ListofFigures ............................................................................................................................................ vi
Abstract .....................................................................................................................................................vii
ExecutiveSummary................................................................................................................................... 1
1.0 Introduction ................................................................................................................................. 19
1.1. WorldwideWindandSolarCapacity................................................................................... 22
2.0 WindIntegrationStudiesintheUnitedStatesandWorldwide .......................................... 27
2.1 SummaryofVariousAssessmentsoftheImpactsofWindonReserves ........................ 29
2.2 SummaryofEstimatedCostImpactsforAdditionalReservesfromWindEnergy....... 31
2.3 UnitCommitmentImpacts..................................................................................................... 36
2.4 WindandNaturalGasStorage.............................................................................................. 37
2.5 ChangestoReserveService.................................................................................................... 37
2.6 Implications
for
California ..................................................................................................... 383.0 MarketStructureandCapacityCredit..................................................................................... 39
3.1 MarketSchedulingandBalancingRequirements............................................................... 39
3.2 ResourceDelivery(CapacityCredit) .................................................................................... 40
3.3 ImplicationsforCalifornia ..................................................................................................... 43
4.0 OperationalIssuestoDate......................................................................................................... 45
4.1 MinimumLoad ........................................................................................................................ 45
4.2 Ramping.................................................................................................................................... 46
4.3 TransmissionRatingandGenerationOverflow ................................................................. 51
5.0 MitigationandOperatingSolutionsToDate..........................................................................53
5.1 WindForecasting ..................................................................................................................... 53
5.2 GridCodes ................................................................................................................................ 59
5.2 WindTurbineModelingandVerification............................................................................ 64
5.4 DemandResponse ................................................................................................................... 67
5.5 Storage....................................................................................................................................... 67
5.6 WindPowerCurtailment ....................................................................................................... 68
5.7 TransmissionPlanningandDevelopment........................................................................... 70
6.0FindingsandImplicationsforCalifornia ....................................................................................... 73
6.1 AncillaryServices .................................................................................................................... 73
6.2 WindForecasting ..................................................................................................................... 74
6.3 Transmission ............................................................................................................................ 746.4 ActiveManagementofWindGeneration ............................................................................ 75
6.5 FlexibleGeneration.................................................................................................................. 75
6.6 Storage....................................................................................................................................... 76
6.7 DemandResponse ................................................................................................................... 76
7.0 Conclusion ................................................................................................................................... 77
7.1 BenefitstoCalifornia............................................................................................................... 79
References......................................................................................................................................81
7/31/2019 AA WindModel
6/99
iv
Appendix A Review of International Experience Integrating Variable Renewable EnergyGeneration. Appendix A: Denmark
Appendix B Review of International Experience Integrating Variable Renewable EnergyGeneration. Appendix B: Germany
Appendix C Review of International Experience Integrating Variable Renewable EnergyGeneration. Appendix C: India
Appendix D Review of International Experience Integrating Variable Renewable Energy
Generation. Appendix D: Spain
7/31/2019 AA WindModel
7/99
v
List of Tables
Table ES-1. Examples of wind power penetration levels, 2005..................................................... 2
Table ES-2. Reserve definitions in Germany, Ireland and the United States ................................. 3
Table ES-3: Estimated ancillary service costs from various wind integration studies inthe United States ..................................................................................................................... 6
Table ES-4. Examples of wind capacity credit methods in the United States................................ 9
Table ES-5. Examples of wind grid codes.................................................................................... 12Table 1. Examples of wind power penetration levels, 2005......................................................... 20
Table 2. Global wind energy capacity by country, 2006 .............................................................. 23
Table 3. Twenty largest grid-connected photovoltaic systems..................................................... 25Table 4. Reserve definitions in Germany, Ireland, and the United States.................................... 28
Table 5. Estimated ancillary service costs from various wind integration studies in the United
States..................................................................................................................................... 33
Table 6. Estimated financial impacts on the Public Service Company of Colorados gas supply
due to wind generation variability and uncertainty............................................................... 37Table 7. Market closing times in various electricity markets ....................................................... 39
Table 8. Factors positively and negatively affecting the capacity credit of wind power.............. 41Table 9. Examples of wind capacity credit methods in the United States.................................... 43
Table 10. Estimated capacity credit of various renewable energy technologies as compared to a
medium-sized gas plant......................................................................................................... 44Table 11. Overview of operational short-term wind power forecast models in Europe............... 54
Table 12. Examples of wind grid codes........................................................................................ 60
Table 13. Power control requirements for wind turbines ............................................................ 62
Table 14. Summary of performance tests and results for the Woolnorth Wind Farm.................. 66
7/31/2019 AA WindModel
8/99
vi
List of Figures
Figure ES-1. Range of findings of additional reserve costs from wind generators ...................... 4
Figure ES-2. Estimated increase in reserve requirements from wind from various studies in
Europe..................................................................................................................................... 5Figure ES-3. Capacity credit values................................................................................................ 8
Figure ES-4. Frequency control requirements by selected country.............................................. 13Figure 1: Worldwide PV installations in 2005 (MW) .................................................................. 24
Figure 2. Range of findings of additional reserve costs from wind generators .......................... 32
Figure 3. Estimated increase in reserve requirements from wind from various studies in Europe
............................................................................................................................................... 34Figure 4: Capacity credit values ................................................................................................... 42
Figure 5: Simulated hourly wind generation changes in New York, 200103............................. 48
Figure 6: Estimated total wind ramping requirements in California 2002 ................................... 50Figure 7: Estimated solar ramping requirements in California - 2002 ......................................... 51
Figure 8: Frequency control requirements by selected country.................................................... 63Figure 9: Proposed transmission projects in the West.................................................................. 72
7/31/2019 AA WindModel
9/99
vii
Abstract
ThisreportsummarizestheexperienceintheUnitedStatesandinternationallythrough2006
withintegratingvariablerenewableenergygeneration,primarilywindgeneration,and
discussespotentialoperatingandmitigationstrategiesforincorporatingvariablerenewable
energygeneration.
Initially,
wind
development
in
Europe,
particularly
in
Denmark
and
Germany,consistedofsmallerbutnumerouswindprojectsinterconnectedtothedistribution
grid,incontrastwithlarger,utilityscalewindprojectsinterconnectedtothetransmissiongrid
intheUnitedStates.ThedifferencesbetweenEuropeandtheUnitedStatesarestartingto
narrowasdevelopmentofvariablerenewableenergygeneration(e.g.windandsolar)increases
andaswinddevelopmenttakesplaceinmorecountries.Inaddition,asmoreutilityscalewind
projectsemerge,morecountriesarerelyingoncommonstrategies,suchasgridcodes,tohelp
integratevariablerenewableenergygeneration.ThisreportisapartoftheIntermittency
AnalysisProject(IAP),acomprehensiveprojectaimedatassessingtheimpactofincreasing
penetrationofvariablerenewableenergygenerationinCalifornia.Areviewoftheinternational
experience
will
provide
perspective
and
insight
to
the
IAP
analysis
team
on
various
techniques
formanagingintermittency.
Keywords:windintegration,solarvariability,windforecasting,variablerenewableenergy
generation,windforecasting,transmission,VARsupport,reserves,ramprates,gridcode,
ancillaryservices.
7/31/2019 AA WindModel
10/99
viii
7/31/2019 AA WindModel
11/99
1
Executive Summary
IntroductionCaliforniasrenewablepolicytargetsof20percentrenewableenergyby2010and33percentby
2020are
likely
to
be
met
with
significant
amounts
of
variable
renewable
energy
generating
resourcessuchaswindandsolarpower.Theanticipatedgrowthintheserenewablesourcesis
challengingdecisionmakerstolookathowtheCaliforniagridwillaccommodatethese
resources.Someanswersarefoundbyexamininginternationalexperience,wherewind
developmenthasbeengrowingsteadilyforseveralyears,andsolargeneratingcapacityis
accelerating.Bytheendof2006,over74gigawatts(GW)ofwindpowercapacityhasbeen
installedworldwide,withtwothirdsofthatinEurope.Bytheendof2005,aboutfiveGWof
gridconnectedsolarpowerisinstalledworldwide,withoverhalfofthatcapacitylocatedin
Germany.
PurposeAlthoughtherearenumerousstudiesestimatingpotentialwindintegrationcoststhatrelyon
modelsandpowersimulations,thereislittleinformationthatprovidesactualexperiencewith
increasinglevelsofvariablerenewableenergygeneration.Thisreportwilldiscussresultsfrom
bothactualexperienceandstudiesthatrelyonmodelsandsimulations,andwillattemptto
distinguishbetweenthosetwothroughoutthedocument. Thisreportispartofthe
IntermittencyAnalysisProject(IAP)andisfundedbytheCaliforniaEnergyCommissions
PublicInterestEnergyResearch(PIER)Program.TheIAPisacomprehensiveanalysisproject
aimedatassessingtheimpactofincreasingpenetrationofvariablerenewableenergygeneration
inCalifornia.Areviewoftheinternationalexperiencewillprovideperspectiveandinsightto
theIAPanalysisteamonvarioustechniquesformanagingintermittency.TheIAPwillmodel
fourscenariosofincreasinglevelsofvariablerenewableenergygeneratingresources,and
assessthepotentialgridimpactsandproposemarketandoperationstrategiestomitigate
impacts,ifanyareidentified.
MarketPenetrationWorldwidewindcapacityismorethan74GWbytheendof2006,withEuropeaccountingfor
twothirdsofthatcapacity.Germanyhasthemostinstalledwindcapacitywithover20GW,
followedbySpain(11GW),theUnitedStates(11GW),India(6GW)andDenmark(3GW).Byenergycontribution,Denmarkistheworldleader,withover18percentofitsenergycomingfromwind.Someregionswithincountrieshaveevengreaterpenetrationsofwindpower,as
indicatedin
Table
ES
1.
Germanyaccountsformorethanhalfoftheworldsinstalledsolarcapacity,withtheUnited
StatesandJapanthenextleadingcountries.Thereislessgridexperiencewithsolarcapacityas
thereiswithwindpower,inpartbecauselargergridconnectedsolarfacilitiesarejustnow
comingonline.Ofthe20largestsolarfacilitiesintheworld,onlyfourwereinstalledbefore
2004.Forthatreason,thisreportwillmostlyfocusonwindpower.
7/31/2019 AA WindModel
12/99
2
Table ES-1. Examples of wind power penetration levels, 2005
Country or region Installed wind
capacity
(MW)
Total installed
power capacity
(MW)
Average
annual
penetration
levela(%)
Peak
penetration
levelb
(%)
Western Denmark 3,128 7,488 ~23 >100Germany: 18,428 124,268 ~5 n.a.
Schleswig-Holstein 2,275 _________c ~28 >100
Spain 10,028 69,428 ~8 ~25%
Island systems:
Swedish island of
Gotlandd
90 No local generation
in normal state
~22 >100
n.a. = Not availableaWind energy production as share of system consumption
bLevel at high wind production and low energy demand, hence, if peak penetration level is >100%
excess energy is exported to other regions.cGerman coastal province
d2002 data. The island of Gotland has a network connection to the Swedish mainland.
Source: Adapted from Soder, Lennart and Ackerman, Thomas (2005). Wind Power in Power Systems: AnIntroduction, In T. Ackerman (Ed.), Wind Power in Power Systems(pp. 25-51). England: John Wiley andSons, Ltd. Updated and adapted by the author. Reproduced with permission.
MarketOperationsEuropeusesdifferentterminologyindescribingtheancillaryservicesnecessarytomaintain
gridreliabilitythantheUnitedStates(TableES2).InEurope,primaryreservesassistwiththe
shortterm,
minute
to
minute
balancing
and
control
of
the
power
system
frequency,
and
is
equivalentintheUnitedStatestoregulation.SecondaryreservesinEuropetakeoverfor
primaryreserves10to30minuteslater,freeingupcapacitytobeusedasprimaryreserves.
LongertermreservesinEuropearecalledtertiaryreservesandareavailableintheperiodsafter
secondaryreserves.Sincewearefocusedoninternationalexperiencewithintegratingvariable
renewableenergygeneration,wewillusethetermsprimaryandsecondaryreservesforthis
report.
Todate,gridreliabilityhasbeenmaintainedaswindandsolarcapacityhasbeenincorporated.
Thelargestimpactofwindappearstobeonsecondaryreserves.Windhashadlittleeffecton
primaryreserves,asthevariationsinwindpowerarerandom.Whenaggregatedwithloadand
generationvariations,
the
variations
from
wind
power
tend
to
be
small
or
cancel
each
other
out.
Sofar,Denmark,GermanyandSpainhavenotchangedtheamountofprimaryreserves
requiredtomaintainsystemreliability,andwindintegrationstudiesconductedinGermany
andtheUnitedStudieshavealsofoundthatonlysmallamountsofadditionalregulating
reservesarerequired.
7/31/2019 AA WindModel
13/99
3
Table ES-2. Reserve definitions in Germany, Ireland and the United StatesShort-term
reserves
Medium-term
Reserves
Long-term
reserves
Germany Primary reserve:
available within 30
seconds, releasedby transmission
system operator
Secondary
reserve: available
within 5 minutes,released by
transmission
system operator
Minute reserve:
available within
15 minutes,called by
transmission
system operator
from supplier
n/a
Ireland Primary operating
reserve: available
within 15 seconds
(inertial response/
fast response)
Secondary
operating reserve:
operates over
timeframe of 15-
90 seconds
Tertiary
response: from
90 seconds
onwards
(dynamic or static
reserve)
n/a
United States Regulation horizon:
1 minute to 1 hour
with 1- to 5-second
Load-following horizons: 1 hour within
increments 5- to 10 -minute
increments (intra-hour) and several
hours (inter-hour)
Unit-
commitment
horizon: 1 day to
1 week with 1-
hour time
increments
Source: Gul, T. and Stenzel, T. 2005. Variability of Wind Power and Other Renewables: ManagementOptions and Strategies. Paris: International Energy Agency
Includingbothprimaryandsecondaryreservecosts,itappearsthatthecostofintegratingwind
isless
than
$6/MWh
at
energy
penetration
levels
of
up
to
20
percent
(Figure
ES
1).
Caution
shouldbeusedininterpretingFigureES1,asthestudiesemploydifferentmethodologies,data,
timescales,andtools.Forexample,theE.OnNetzdatainFigureES1measuresreserve
impactsofwindonadayaheadbasis,whileotherstudiesmeasurereserveimpactsduringthe
hour;theresultsillustratethatwindcannotbeforecastedasaccuratelyonadayaheadbasisas
onetotwohoursahead.
Factorsthataffectwindintegrationcostsinclude:
Howthevariabilityinwindgenerationinteractswiththevariabilityinelectricity
demand
Thegeographic
concentration
of
wind
projects
Howfarinadvancethepowerschedulesmustbesubmittedtosystemoperators.
7/31/2019 AA WindModel
14/99
4
Figure ES-1. Range of findings of additional reserve costs from wind generatorsSource: Adapted from Gross, Robert; Heptonstall, Philip; Anderson, Dennis; Green, Tim; Leach, Matthew;and Skea, Jim. (2006). The Costs and Impacts of Intermittency. London: United Kingdom Energy ResearchCenter. Available at http://www.ukerc.ac.uk/content/view/258/852. British currency converted to U.S. $ usinga conversion of $1.8717 per British pound, as of May 25, 2006. Denmark 2002 from Ackerman, Thomas;Morthorst, Poul Erik. 2005. Economic Aspects of Wind Power in Power Systems. In T. Ackerman (Ed.),Wind Power in PowerSystems (pp. 384-410). England: John Wiley and Sons, Ltd. National Grid numbersfrom National Grid Transco. 2004. Submission to the Enterprise and Culture Committee: Renewable Energyin Scotland Inquiry. Available at www.scottish.parliament.uk.. Sustainable Energy numbers from SustainableEnergy Ireland. 2004. Operating Reserve Requirements as Wind Power Penetration Increases in the IrishElectricity System. Available at http://www.sei.ie/uploadedfiles/InfoCentre/IlexWindReserrev2FSFinal.pdf.See Reference for details.
Country Comments Reference
1 UKLower bound estimates based on analysis from NEMCO (Australia), Lewis Dale of National
Grid, SCAR Study and Millsborrow 2002
Mott MacDonald,
2003.
2 Nordic Based on data collected in Finland, Sweden, Norway and Denmark Holttinen, 2004.
3 UK Dale, Milborrow SCAR, PIU studies Dale et al 2003.
4 UK Based on modeling efforts Ilex & Strbac, 2002.
5 Ireland Numbers derived from analysis of international experience, specifically, Denmark, US (BPA) Millborrow, 2004.
6 Ireland Study conducted for Sustainable Energy Ireland, estimates based on modeling analysis Ilex et al, 2004.
7 Denmark Actual costs to Eltra, Danish grid operator Pedersen et al, 2002
8 UK Estimates based on the technical standards of the National Grid Company Milborrow, 2001a
9a Spain Low market costs of procuring the difference between predicted and actual generation Fabbri et al, 2005.
9b Spain High market costs of procuring the difference between predicted and actual generation Fabbri et al, 2005.
10 UK Estimates based on 2001 market data for imbalances Dale, 2002
11 Germany Figures derived from analysis of E.On Netz study Milborrow, 2005a
12a Denmark Low estimate based on Nord Pool balancing market (2002 prices Ackerman et al, 2005
12b Denmark High estimate based on Nord Pool balancing market (2002 prices) Ackerman et al, 2005
13a ScotlandNational Grid estimates for balancing costs with 10 % penetration of wind in the UK, asreported to the Scottish Parliament
National GridTransco, 2004
13b ScotlandNational Grid estimates for balancing costs with 20 % penetration of wind in the UK, as
reported to the Scottish Parliament
National Grid
Transco, 2004
1
2
34
5
6
8
7
9a
9b
10
11
12a
12b13a
13b
0
2
4
6
8
10
12
14
16
0 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45
Intermittent generation level penetration level (% of total system energy)
Reservecost
($/MWh)
1
2
3
4
5
6
7
8
9a
9b
10
11
12a
12b
13a
13b
7/31/2019 AA WindModel
15/99
5
Submittingschedulesclosertotherealtimemarketwillallowformoreaccuratepredictionsof
windgeneration,althoughsometradeoffsareinvolved.Havingashorterperiodoftimebefore
thestartofrealtimemarketoperationsmayleadtoaneedformoreflexibleoperatingreserves,
orperhapshighercostsfromtheincreasedstartingandstoppingofconventionalunits.The
shorterperiodsoftimemaynotallowsufficienttimetochangeunitcommitmentdecisionsfor
conventionalgenerating
units.
This
problem
can
be
simply
addressed
with
awind
plant
scheduleupdate.
FigureES2illustratestheestimatedpercentageincreaseinreservesfromwindfromseveral
windintegrationstudiesinEurope.Themethodologydifferssignificantlybystudy,making
theseresultsnotdirectlycomparable.Forexample,thedenastudyinGermanyestimated
reserverequirementsonadayaheadbasis,whiletheUnitedKingdomandSwedenstudies
estimatedreserverequirementsfourhoursahead.Theotherstudiesestimatedtheimpacton
reservesfromwindvariabilityduringtheoperatinghour.Generally,FigureES2suggeststhat
anincreaseinreservesislikelywithhigherlevelsofwindpenetration.
Figure ES-2. Estimated increase in reserve requirements from windfrom various studies in EuropeSource: Holttinen, Hannele, Pete Meibom, Antje Orths, Frans Van Hulle, Cornel Ensslin,Lutz Hofmann, John McCann, Jan Pierik, John Olav Tande, Ana Estanqueiro, LennartSoder, Goran Strbac, Brian Parsons, J. Charles Smith and Bettina Lemstrom. Design andOperation of Power Systems with Large Amounts of Wind Power: First Results ofInternational Energy Agency Collaboration. Global Wind Power Conference, Adelaide,Australia. September 18-21, 2006.http://www.ieawind.org/AnnexXXV/Meetings/Oklahoma/IEA%20SysOp%20GWPC2006%20paper_final.pdf. (accessed November 8, 2006).
WindintegrationstudiesconductedintheUnitedStateshaveoftenfocusedonunitcommitment,thetimeframewheregeneratorsarecommittedinadvancetomeetexpected
demand(TableES3).Thisiswhereimprovementsinwindforecastingarelikelytohavethe
greatestimpact.Ingeneral,theEuropeanstudiesdidnotfocusasmuchonunitcommitment
issues.
Increase in reserve requirement
0 %
1 %
2 %
3 %
4 %
5 %
6 %
7 %
8 %
9 %
10 %
0 % 5 % 10 % 15 % 20 % 25 %
Wind penetration (% of gross demand)
Increaseas%o
fwindcapacit Nordel: SE, NO, FI, DK
Finland
Sweden
Ireland
UK
Sweden 4 hours ahead
dena Germany
7/31/2019 AA WindModel
16/99
6
Table ES-3: Estimated ancillary service costs from various wind integrationstudies in the United States
Study Wind
Penetration
(%)
Regulation
$/MWh
Load
Following
$/MWh
Unit
Commitment
$/MWh
Gas
Supply
Cost
($/MWh)
Total
$/MWh
UWIG/Xcel 3.5 0 0.41 1.44 NA 1.85
PacifiCorp 20 0 1.64 3.00 NA 4.64
BPA/Hirst 7 0.19 0.28 1.00-1.80 NA 1.47-2.27
PJM/Hirst 0.06-0.12 0.05-0.30 0.70-2.80 N/A NA 0.75-3.10
We
Energies I
4 1.12 0.09 0.69 NA 1.90
We
Energies II
29 1.02 0.15 1.75 NA 2.92
Great River
Energy I
4.3 NA NA NA NA 3.19
Great River
Energy II
16.6 NA NA NA NA 4.53
CA RPS
Phase III
4 0.46 NA NA NA NA
MN
DOC/Xcel
15 0.23 0 4.37 NA 4.60
Xcel-PSCo 10 0.20 NA 3.32 1.26 3.72
Xcel-PSCo 15 0.20 NA 3.32 1.45 4.97
Sources: Parsons, Brian, et al: Grid Impacts on Wind Power Variability: Recent Assessments from aVariety of Utilities in the United States. Paper given to Nordic Wind Power Conference, May 22-23, 2006,Finland; and Smith, J.C.; DeMeo, E.; Parsons, B.; and Milligan, M. Wind Power Impacts on Electric-Power-
System Operating Costs: Summary and Perspective on Work to Date. March 2004. Presented to theAmerican Wind Energy Conference, Chicago, Illinois. www.nrel.gov/docs/fy04osti/35946.pdf. (accessedJune 2, 2006).
AlthoughpresentoperatingpracticesinEuropehavesuccessfullyintegratedwindpower,
currentinitiativesindicatethatchangesmaybenecessaryasmorewindpowercomesonline.
Amongotherinitiatives:
TheEuropeanTransmissionSystemOperators(TSO),theassociationoftransmission
systemoperatorsinEurope,isconductingaEuropewidewindintegrationstudy,with
resultsdueby2008.
TheInternational
Energy
Agency
(IEA)
is
sponsoring
an
annex,
Design
and
Operation
ofPowerSystemswithLargeAmountsofWindPowerProduction,thatbeganin
mid2006.
InAsia,thesituationisdifferentinChinaandIndia,asthelackofgridinfrastructureseverely
handicapsnotonlywinddevelopmentandoperationsbutalsotheeconomyasawholeinboth
countries.
7/31/2019 AA WindModel
17/99
7
CapacityCreditofWindAreviewofvariousstudiesestimatingthecapacitycreditofwindpowerinEuropeindicated
thatwindhasacapacitycreditgreaterthanzero,andalsothatthecapacitycreditdecreasesas
thelevelofwindgenerationrises.ThesefindingsareillustratedinFigureES3.Capacitycredit
studies
for
wind
in
the
United
States
have
not
generally
measured
the
capacity
credit
of
wind
versusthemarketpenetrationofwind.Instead,thesestudieshavefocusedmoreonthe
methodsandmechanicsofdeterminingthecapacitycreditforwind.Avarietyofapproaches
havebeenusedintheUnitedStatesfordeterminingthecapacitycreditofwind,rangingfrom
determiningtheequivalentloadcarryingcapabilityofwind;usingaproxyvalue;applyingthe
capacityfactorofwindduringpeakdemandhours;andusingthecapacityvalueofwind
duringafractionofthetoppeakdemandhours(TableES4).
AswithFigureES1,cautionshouldbeusedininterpretingFigureES3andTableES4,as
differentstudymethodologies,assumptionsanddatawereusedinseveralofthesestudies.
OperatingIssuestoDateMinimumLoad:Definedsimply,minimumloadisthesmallestamountofloadonthegrid
duringadefinedperiodoftime.Windproductionmaycoincidewithtimesofminimumload
andaddtosystemchallengesinmanagingthegrid.
WindintegrationinDenmarkandGermanyhasbeeneasedconsiderablybytheextensive
interconnectionsthetwocountrieshavewithneighboringcountries.AttimesinDenmark,
hourlywindproductioncanexceedloaddemand,andconventionalpowerplantshaveto
reducetheirproductionuntilthesupplyanddemandbalanceisrestored.Ontheseoccasions,
spotpricesmaydroptozero,asoccurredfor83hoursinDenmarkin2003.GeneralElectrics
windintegrationstudyfortheNewYorkStateEnergyResearchandDevelopmentAuthority
(NYSERDA)found
that
minimum
load
is
not
asignificant
issue
with
10
percent
wind
penetration,asNewYorkisanenergyimporterwithoutwindandremainsanimporterwith
wind.
Californiahasthepotentialforminimumloadissues.Theseissuesinclude:
MustrunqualifyingfacilitycontractsunderthePublicUtilityRegulatoryPoliciesAct.
Increasedprocurementofcombinedcyclenaturalgasprojectsthatoperatebaseloadand
aroundtheclock.1
1Anotherpotentialneartermcontributortominimumloadissuesisthearoundtheclockenergy
procurementcontractsthattheCaliforniaDepartmentofWaterResourcessignedduringtheelectricity
crisisof2000and2001.However,thesecontractsexpirebetween2009and2011,likelybeforevariable
renewablesmayreachhighlevelsofmarketpenetrationinCalifornia.
7/31/2019 AA WindModel
18/99
8
Country Comments Reference
1 Ireland Estimate of capacity credit values for an island system Watson 2001
2 UK
Estimates based on analysis from a three different
sources, Central Electricity Generating Board, National
Grid, and System Costs of Additional Renewables
(SCAR Report)
Mott
MacDonald
2003
3 Germany Dena project steering group Dena 2005
4 UKExamines the CEGB and SCAR reports and adjusts
them for greater penetrations of wind
Dale, et al.,
2003
5 UK Based on modelingIlex and Strbac,
2002
6 N. EuropeEstimates based on reanalysis data collected from
operating wind facilitiesGiebel, 2000
7 UK Early assessment of capacity of wind projects in the UK Grubb 1991
8 Germany E. On NetzE. On Netz
2005
9 UK Study Commissioned by UK Government Sinden 2005
Figure ES-3. Capacity credit valuesSource: Adapted from Gross, Robert; Heptonstall, Philip; Anderson, Dennis; Green, Tim; Leach,Matthew; and Skea, Jim. (2006). The Costs and Impacts of Intermittency. London: United KingdomEnergy Research Center. Available at http://www.ukerc.ac.uk/content/view/258/852. See Reference fordetails.
TheCaliforniaIndependentSystemOperator(CAISO)notedthatminimumloadconditionscan
beexacerbatedinAprilandMaywhenhydroelectricitygeneration,consideredmusttake,
increasesbecauseofsnowmeltandwhenwindgenerationcorrespondinglyisatahighlevelas
well.
1
2
3
4 567
8
9
0
5
10
15
20
25
30
35
40
0 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39
Intermittent generation penetration level (% of total system energy)
CapacityCredit(%
ofinstalled
intermittentgenerationcapacity)
1
2
3
45
6
7
8
9
7/31/2019 AA WindModel
19/99
9
Table ES-4. Examples of wind capacity credit methods in the United States
Region/Utility Method Note
CA/CEC ELCC Rank bid evaluations for RPS (low 20s)
PJM Peak Period
Jun-Aug from 3 p.m.-7 p.m., capacity factor using 3-
year rolling average (20%, fold in actual data when
available)
ERCOT 10%May change to capacity factor, 4 p.m.-6 p.m., Jul
(2.8%)
MN/DOC/Xcel ELCC Sequential Monte Carlo (26-34%)
GE/NYSERDA ELCC Offshore/onshore (40%/10%)
CO PUC/Xcel ELCC
PUC decision (30%) and Current Enernex study
possible follow-on, Xcel using MAPP approach (10%)
in internal work
RMATS Rule of thumb 20% all sites in RMATS
PacifiCorp ELCC Sequential Monte Carlo (20%)
MAPP Peak Period Monthly 4-hour window, median
PGE 33% (method not stated)
Idaho Power Peak Period 4 p.m.-8 p.m. capacity factor during July (5%)
PSE and Avista Peak PeriodPSE will revisit the issue (lesser of 20% or 2/3 Jan
C.F.)
SPP Peak Period Top 10% loads/month; 85th
percentile
Source: Milligan, Michael, and Kevin Porter (2005). Determining the Capacity Value of Wind: A Survey ofMethods and Implementation. Golden, CO: National Renewable Energy Laboratory. Available atwww.nrel.gov/docs/fy05osti/38062.pdf.
Ramping:Attimes,windgenerationcanrampupanddownquickly,particularlyinresponseto
storms.In
general,
ramping
events
are
of
more
concern
to
smaller,
weaker
grids
with
few
externalinterconnectionsandgridswithlargeconcentrationsofwindprojectsinoneregion.
Gridswiththesefeaturestypicallydonothaveadeepstackofgeneratingresources,
connectionstootherregionsorthelargegeographicdiversityofwindresourcestomanage
rampingevents.Forthisreason,theTSOsthathaveproposedorimplementedrampinglimits
onwindturbineshavetendedtobesmallergridsorgridswithfewexternalinterconnections.
OneexceptionisinGermany,wheretheTSOslimitthepositiveramprateofwindgenerationto
10percentofratedpowerperminute.Someexamplesincludethefollowing:
EirGridinIrelandlimitsthepositiveramprateto130MWperminute
Scotland,
where
the
positive
ramp
rate
is
limited
to
110
MW
per
minute,
depending
on
thecapacityofthewindproject,andthedownwardramprateto3.3percentofpower
outputperminute
TheAlbertaElectricSystemOperatorhasproposedlimitingsystemwiderampratesfor
windprojectsto4MWperminute.
7/31/2019 AA WindModel
20/99
10
TheIAPwillassesstherampingimpactsofvariableresourcesontheCaliforniagrid.Asastate,
CaliforniahasarelativelydeepresourcestackandinterconnectionswiththePacificNorthwest
andtheSouthwest.Californiaisnotintheextremesituationasislandsorsmallergrids.In2006
theCaliforniaWindEnergyCollaborative(CWEC),underaconsultingagreementtotheEnergy
Commission,examinedrampingcapabilityintheCAISObasedonpubliclyavailabledata.
CWECdetermined
that
the
CAISO
had
sufficient
ramping
capability
to
accommodate
load
variabilityandcurrentlevelsofvariablerenewableenergygeneration.
TransmissionRatingandUnscheduledGeneration:Attimes,thecombinationofwindfrom
DenmarkandGermanycanresultinunscheduledpowerflowsontheEuropeantransmission
grid,especiallyduringtimesofhighwindproductionandlowdemand.Thelackofsufficient
northtosouthtransmissioninGermanyresultsinwindgenerationfromNorthernGermany
beingtransmittedtocustomersinSouthernGermanyviathetransmissionnetworksofthe
Netherlands,BelgiumandFrance.
In2005theElectricPowerGroup(EPG),underconsultingagreementtotheEnergy
Commission,suggested
that
the
frequency
response
of
generating
resources
in
California
and
throughouttheWesternElectricityCoordinatingCouncil(WECC)hasdecreasedinrecentyears
becauseofseveralgeneratingresourcesoperatingatbaseloadwithlimitedupwardcapability.
That,inturn,couldleadtoreducedtransmissionpathratingsintoCaliforniaandthroughout
WECC.Furthermore,theEPGfoundthatasignificantresourceshifttomorerenewable
resourcesinWECC,withoutcorrespondingattentiontothethermalcapabilityofgenerators,
voltagesupport,andhowgeneratorsperformduringcontingencyevents,couldcompoundthis
issue.Theimpact,ifany,wouldarisemostlikelyduringnonpeakhours.
MitigationandOperatingSolutionstoDateSeveral
strategies
have
been
proposed
and
implemented
to
integrate
variable
renewable
energy
generation,primarilywind.Theseincludewindforecasting,gridcodes,curtailment,wind
turbinemodelingandverification,demandresponse,andtransmissionplanningand
development.
WindForecasting:Ingeneral,windgenerationcanbepredictedmoreaccuratelythecloserit
occurstoactualoperation.Windgenerationcanbepredictedwithabout90percentorgreater
accuracyonehourahead,with70percentaccuracyninehoursaheadbutonlyabout50percent
accuracy36hoursahead.Themeanabsoluteerrorbyinstalledcapacityforwindforecastingin
Denmarkistypicallybetween8and9percent,whichisequivalenttoa38percentforecasterror
byenergy.InGermany,therootsquaremeanerror(RSME)ofwindforecastsis5to8percentof
installedwind
capacity
with
maximum
errors
ranging
from
30
to
40
percent
of
installed
wind
capacity.OnafourhouraheadbasisinGermany,theRSMEis3.8percent,withamaximum
errorrangingfrom28to36percent.
Contributorstowindforecastingerrorsincludephaseerrors,whichoccurwhenwind
forecastspredictstorms.Inpractice,thestormmayoccurafewhoursaheadorfewhours
behindthewindforecast.Anothercontributortowindforecastingerrorsistherelativelylow
spatialandtemporalqualityofmeteorologicaldata.Mostforecastinghasbeenfocusedon
7/31/2019 AA WindModel
21/99
11
weatherattributessuchasprecipitationandtemperature,withalowerspatialandtemporal
resolutionthanisrequiredforwindgeneration.Manybusinessandgovernmentalentitiesare
becominginterestedinfiner,morepreciseforecasting,andthatinturnmaycorrespondto
betterdataforimprovingwindforecasting.
In
2002,
the
CAISO
became
the
first,
and
to
date
the
only,
regional
transmission
operator
in
the
UnitedStatestooffercentralizedwindforecastingtopredicttheoutputofvariablerenewable
energygeneration.TheParticipatingIntermittentResourceProgram(PIRP)isvoluntary.To
date,onlywindgenerationisenrolledinPIRP,althoughwithseveralproposedlargescalesolar
projectsinCalifornia,itispossiblethatsolarwilljoinwindinthePIRPprogram.InPIRP,the
positiveandnegativeimbalancesassociatedwiththe10minuteschedulesofwindpower
generatorsarenettedoutandsettledonamonthlybasis,withthenotionthattheseimbalances
willcanceloutoverthemonth.Anynetimbalancesattheendofthemonth,positiveor
negative,aresettledattheweightedaveragezonalmarketclearingprice.TheCAISOisallowed
tochargepenaltiesforexcessivedeviationsofageneratorcomparedtoadvanceschedulesbut
doesnotatthistime.IftheCAISOchargesthispenalty,participatingintermittentresourcesin
PIRPwould
be
exempt.
Initially,PIRPwashandicappedbymissingtelemetrydatacausingvariationsinthewind
forecast;however,mostofthistypeoferrorhasbeencorrected.Therearesomemarket
participantconcernsregardingthereallocationofcostsfromwhichparticipatingintermittent
resourcesareexempt.TheCAISOisexploringmakingseveralenhancementsandchangesin
hopesofreducingthesecostconcerns.Theseenhancementsincludeincreasingtheforecasting
feesforbeinginPIRPandsubjectingpowerexportsfromparticipatingintermittentresourcesto
higherfees.InDecember2006,theFederalEnergyRegulatoryCommission(FERC)approved
theCAISOspetitiontochargeanexportfeetoPIRPfacilitiesthatexportpoweroutofthe
CAISO
control
area.
GridCodes:Acommonapproachtakenbymanytransmissionsystemoperatorstoincorporate
wind,istoadoptgridcodesspecifictowindgenerators.Germanyintroducedtheirwindgrid
codein2003,followedbyDenmarksTSOsinlate2004.Britain,Ireland,andtheUnitedStates
havesincefollowedwithwindgridcodesin2005.
Theintentistoensurethatwindprojectsdonotnegativelyimpactreliability.Alargeamountof
windcapacitytrippingofflineinresponsetoagriddisturbancecouldleadtoafallinvoltage
and/orfrequency.That,inturn,couldcontributetoothergeneratorstrippingoffthegridand
couldresultinnothavingenoughgenerationtomeetload.Thegridcodeshaveemergedona
transmissionoperatororcountrybasis,anddifferencesbetweenthegridcodeshavenaturally
resulted.To
date,
wind
specific
grid
codes
have
required
wind
power
facilities
to
address
one
ormoreofthefollowingconditionsto:
Ridethroughgridfaults
IncreaseordecreasepowergenerationattheTSOsrequest
Supplyreactivepower
Adjustpowergenerationinresponsetofrequencychanges
7/31/2019 AA WindModel
22/99
12
Controlorlimitrampingincreases.
Generally,allwindgridcodeshaveafaultridethroughrequirementspecifyingthatwind
generatorsmuststayconnectedforaperiodoftimewhenfaultsoccuronthetransmission
systemandvoltagedrops.AsindicatedinTableES5,faultridethroughrequirementsdifferby
country.
Table ES-5. Examples of wind grid codes
Grid Code Fault Duration
(Milliseconds)
Voltage Drop
During Fault
(% Nominal)
Voltage Recovery
(Milliseconds)
Denmark 100 25 1000
Germany(E.On) 150 0 1500
Ireland(EirGrid) 625 15 3000
UK(NGT) 140 0 1200
Spain 500 20 1000
UnitedStates 150 0* NA
*As of 2008. For 2007 and for normally cleared three-phase faults, wind turbines must be able to ridethrough voltages down to 15 percent at the point of interconnection for 150 milliseconds. Source:Milborrow, David. 2005b. Going Mainstream at the Grid Face. Windpower Monthly, September 2005,p. 49. Reproduced by permission. United States provisions drawn from Federal Energy RegulatoryCommission. December 12, 2005. Order No. 661-A. Interconnection for Wind Energy.
Asmallernumberofcountriesalsorequirewindturbinestoprovidefrequencyresponsein
ordertomaintainthefrequencyat50Hz(thelevelinEurope).Windturbineshavealimited
abilitytoprovidefrequencycontrolascomparedtoconventionalunits.Tomeetthis
requirement,windturbinesmustbeoperatedatlessthanfulloutput,suchthatbladepitchcan
beadjustedtoincreasegenerationwhencalledupon.Thisisanoptiononnewerpitch
controllableturbines.
Ireland
requires
wind
generators
to
provide
primary
frequency
control
of
35percentofpoweroutputandtoprovidesecondaryfrequencycontrolifcalledupon.
DenmarkandtheUnitedKingdomrequirewindgeneratorstoprovidefrequencycontrolaftera
systemfaultorifpartofthegridisisolated.Similarly,transmissionsystemoperatorsarealso
requiringwindgeneratorstostayonlineduringfrequencydeviations,asindicatedinFigure
ES4.
Gridcodesalsogenerallyrequirewindturbinestooperatecontinuouslyatratedoutputin
normalvoltageranges,tostayonlineduringvoltagechangeswithinaspecifiedrange,andto
supplyreactivepower.Forinstance,E.OnNetzinGermanyrequireswindturbinestocontinue
tosupplyreactivepowerforuptothreesecondsafteravoltagedrop.Sweden,Norwayand
Spainalso
have
provisions
for
wind
turbines
and
reactive
power.
7/31/2019 AA WindModel
23/99
13
Figure ES-4. Frequency control requirements by selected countrySource: Van Hulle, Fran. 2005. Large Scale Integration of Wind Energy in the EuropeanPower Supply. Brussels, Belgium: European Wind Energy Association. Available athttp://www.ewea.org/fileadmin/ewea_documents/documents/publications/grid/051215_Grid_report.pdf.
Inthe
United
States,
FERC
adopted
agrid
code
in
2005
for
wind
turbines.
A
WECC
task
force
is
alsoconsideringpossiblechangestoWECCscurrentlowvoltageridethroughstandardto
lowertheminimumvoltagetoleranceperiodtozeroatthepointofinterconnectionfor12cycles
(about1/5ofasecond).
WindTurbineModelingandValidation:Acommonissuewithwinddevelopmentistheneedto
improvethemodelingofwindprojectsfordeterminingthepotentialimpactsonsystem
reliabilityduringtheevaluationofinterconnectionapplications.Lackofknowledgeby
transmissionsystemoperatorsaboutwind;theincreasingsizeofwindprojects;andtheoften
weaktransmissionnetworkthatwindprojectswereattemptingtointerconnecttohavemade
interconnectionmodelingachallenge.TheWECCWindGeneratorModelingGroupis
preparingwind
turbine
generator
models.
In
Europe,
continued
growth
of
wind
energy
in
some
countriesmaybeconditionedonnotonlyresolvinguncertaintiesaboutthegridimpactsof
windturbinesbutalsoontheavailabilityofvalidatedanalyticaltoolsandmodels.ESBin
Irelandhasinstitutedcertificationrequirementsforwindturbinemodelstobeusedinsystem
interconnectionstudiesaspartofIrelandsgridcode.
DemandResponse:Demandresponsemayhelpintegratelargeramountsofwindpowerby
movingconsumptionfromwhenwindproductionislowtotimesofhigherwindproduction,
7/31/2019 AA WindModel
24/99
14
therebylesseningtherequirementforreservesfromconventionalpowerplants.Oneexample
researchedinDenmarkistouseelectricityproductionfromwindgenerationduringoffpeak
hoursfordistrictwaterheatinginsteadofotherfuels.Sofar,participationindemandresponse
programshasbeenrelativelysmallinEuropeandintheUnitedStates,althoughregulatoryand
industryinterestisgrowing.Californiahassettargetsforutilitiestomeet3percentofitsannual
peakdemand
with
demand
response,
increasing
1percent
per
year
to
5percent
by
2007
and
favorsdemandresponseandenergyefficiencyoverotherresourcesinmeetingnewelectricity
demand.
WindPowerCurtailment:Maximumwindproductioncanbeseveraltimeslargerthanaverage
windproduction,meaningthatat20percentwindpenetrationbyenergy,windproductionmay
equalconsumerdemandforsomehours.Curtailmentofwindgenerationmaybenecessaryif
theamountofwindgenerationataspecifictimeismorethanwhatthegridcanreliablyhandle.
Infact,forgridswithsmallcontrolareasthataredominatedbythermalgenerationthatmaynot
beveryflexible,windcurtailmentscouldoccuratpenetrationsaslowas10percent.
InNorthern
Germany,
E.
On
Netz
implemented
curtailment
policies,
or
generation
managementasdescribedbyE.OnNetz,forwindgeneratorsintheSchleswigHolsteinregion
inmid2003,covering700MW(about1/3ofthewindcapacityinthatregion),andexpandingit
toLowerSaxonyin2005.Ifoverloadconditionsarepresent,E.OnNetzidentifiestheregionof
concernandsendsasignaltowindprojectstoadjustoutputaccordingly,definingthe
maximumactiveoutputthattheregionswindprojectscanprovidetothegrid.Untilnew
transmissioncapacityisadded,E.OnNetzwillnotinterconnectnewwindprojectsin
SchleswigHolsteinunlessthewindgeneratorsparticipateinE.OnNetzsgeneration
managementprogram.Spainalsocurtailedwindgenerationin2004whenwindpower
penetrationexceeded12percentofdemand,duetolocalgridlimitations.Thesewind
curtailments
occurred
less
frequently
in
2005.
TransmissionPlanningandDevelopment:Stronggridinterconnectionshaveplayedapartin
helpingDenmarkmanageitshighlevelofwindproduction.Ingeneral,though,thereislimited
interconnectionbetweennationalandregionalelectricitymarketsinEurope,andcurrenttrans
countryinterconnectionscanbeheavilyloaded.TheInternationalEnergyAgencypredictsthat
$1.8trillionoftransmissionanddistributioninvestmentsarenecessaryby2030simplytomeet
demandgrowthandtoupgradeexistingassetsinEurope.Californiahasextensive
interconnectionswiththePacificNorthwestandwiththeDesertSouthwest,andthestateis
workingonnewtransmissionthatwillbenecessaryifCaliforniaisgoingtomeetits20percent
RPSby2010.Anumberoftransmissionplanningactivitiesareoccurringbothinsideand
outsideof
California.
In
August
2006,
the
CAISO
Board
of
Governors
approved
the
Sun
Path
projectthatwilladd1,000MWoftransmissioncapacitytoSouthernCaliforniaprovidingaccess
togeothermalandsolarresourcesintheImperialValley.TheCAISOBoardofGovernorsis
consideringproposedtransmissionprojectsinTehachapiandtheLakeElsinoreAdvanced
PumpStorage(LEAPS)project.OutsideofCalifornia,morethanadozentransmissionprojects
havebeenproposed,withsomeoftheseproposalstargetingCaliforniaastheultimatemarket.
Manyoftheseproposalsareataveryearlystage,andnotallofthemmaybeconstructed.
7/31/2019 AA WindModel
25/99
15
ConclusionsNearlytwothirdsoftheworldswindinstalledcapacityisinEurope,withGermany,Spain,
andDenmarkaloneaccountingforonehalfoftheworldsinstalledwindcapacity.Wind
developmentinEurope,atleastinitially,differedfromthelargerutilityscaleprojectsinthe
United
States,
particularly
in
Denmark
and
Germany,
where
wind
development
consisted
of
smaller(butnumerous)windprojectsinterconnectedtothedistributiongrid.Thattypeofwind
developmentinDenmarkandGermanytookadvantageofthegeographicdiversityofwind
resourcestosmoothsomeofthevariabilityinwind.
SimilarmanagementstrategiesbetweentheUnitedStatesandEuropehavebeguntoemergeas
winddevelopmenthasexpandedtoothercountrieswithlessrobustgridinfrastructure,as
comparedtoDenmarkandGermany,andaswinddevelopmenthastendedtowardsutility
scaleprojectsthatarecommonintheUnitedStates.Theimplementationofgridcodes(although
varyinginspecificsfromcountrytocountry)isonesuchexample.Theneedfortransmissionin
bothEuropeandtheUnitedStates,notjustforwindgenerationbutforalltypesofgeneration,
isanother
similarity.
Considerable
transmission
planning
and
activity
is
underway
in
both
EuropeandtheUnitedStates.
Theparticularcircumstancesineachcountry,stateorregionwilldeterminetheeaseof
integratingvariablerenewableenergygeneration.Thesefactorsincludethegeneratingmix;the
flexibilityofresourcesinmix;whethertherearerobustdayaheadmarketswithdeepresource
stacks;thelocationofwindresources;transmissionavailability;andthesizeofcontrolareas.
Windintegrationwillalmostcertainlybemorechallenginginsmallcontrolareas,inareaswith
limitedinterconnections,orinareaswithasmallloadand/orsmallresourcestacksascompared
toregionswithlargercontrolareas,extensiveinterconnectionsorlargeloadsand/ordeep
resourcestacks.Becausethesecircumstancescanvarydramatically,cautionshouldbeusedin
comparingcountries
or
regions
with
each
other.
Thisreportexaminedhowcountriesoverseashaveincorporatedvariablerenewableenergy
generation,whatoperatingstrategieshavebeenusedtointegratevariablerenewableenergy
generation,whatlessonshavebeenlearned,andwhetherthatexperienceistransferableto
California.Foravarietyofreasons,thereportfocusedmostlyonwind,giventhatthereismore
gridconnectedwindcapacityworldwidethansolar;theexperiencewithwindismorewidely
reported;andthedevelopmenttodateofsolarsystemshasbeenofsmall,distributedsystems
and,atleastasofnow,doesnotfacethesamesystemintegrationissuesaswindpower.
Somehighlightsofintegrationstrategiesandfindingsfromvariouscountryreportsinclude:
Strategiesimplementedtoincorporatewindincludewindforecasting,gridcodes,
curtailment,windturbinemodelingandverification,demandresponse,and
transmissionplanninganddevelopment.
Todate,gridcodeshavefeaturedthesemajorthemes:requiringwindturbinestoride
throughgridfaults;increasingordecreasingpowergenerationattheTSOsrequest;
supplyingreactivepower;adjustingpowergenerationinresponsetofrequencychanges;
andcontrollingorlimitingrampingincreases.
7/31/2019 AA WindModel
26/99
16
VariousEuropeantransmissionsystemoperatorshaveimplementedmorecontrol
requirementsforwindthanhavebeenseenintheUnitedStatessofar,suchasramprate
limitsandtherequirementtoprovidereservesandfrequencycontrol.Ingeneral,these
controlrequirementshavebeenafunctionofsmallcontrolareasorlimitedtransmission
interconnections,orboth.
Someof
the
more
stringent
wind
control
strategies
have
been
proposed
in
countries
that
havelittleornogridinterconnections,andtheseparticularcircumstancesneedtobe
keptinmindwhencomparinginternationalwindintegrationexperiences.Ramping
eventswillbeofmoreconcerntosmallgrids,orgridswithfewexternal
interconnections,orgridswithalargeconcentrationofwindprojectsinoneregion.
Countrieswithmusttakerequirementsintheirrenewableenergyfeedinlawstendto
havethetoughestgridcodeprovisionswithregardstowindcurtailment.
Indescribingvariousancillaryservices,EuropeandtheUnitedStatesusedifferent
terminology.InEurope,primaryreservesassistwiththeshortterm,minutetominute
balancing
and
control
of
the
power
system
frequency,
and
is
equivalent
in
the
United
Statestoregulation.SecondaryreservesinEuropetakeoverforprimaryreserves10to
30minuteslater,freeingupcapacitytobeusedasprimaryreserves.Theclosest
terminologyintheUnitedStatesforsecondaryreservesiseitheroperatingreservesor
loadfollowingreserves,whichmayincludebothspinningandnonspinning
components.LongertermreservesinEuropearecalledtertiaryreservesandare
availableintheperiodsaftersecondaryreserves.Tertiaryreservesareclosestto
supplementalreservesintheUnitedStates,althoughthetimescalesmaybedifferent
betweenEuropeandtheUnitedStates.
Reconstitutingexistingreserveservicesmaybenecessaryashigherlevelsofvariable
renewable
energy
generation
is
added.
Submittingscheduleswithshorterperiodsoftimebeforetherealtimemarketbegins
willallowformoreaccuratepredictionsofwindgeneration,althoughsometradeoffs
areinvolved.
Variouswindintegrationstudiesandtransmissionsystemoperatorshavereported
someoperatingissueswithwindgeneration,suchasminimumloadandhighramp
rates.ANewZealandwindintegrationstudyusedminimumloadtodeterminehow
muchwindcouldbeaccommodatedonitsgrid.
Forramping,variousstudiessuggestthatwindwillrampupanddownwithin10
percentofcapacitymuchofthetimeoveranhour.Handlingwindrampingcouldbe
managedwith
sufficient
regulation
or
load
following
generation;
wind
forecasting
to
predictvariabilityandrampingevents;performancelimitsonthewindgenerationsuch
asrampratelimits;orsharingreservesorenergyimbalancesovermultiplecontrol
areas.
Effortsarealsounderwayonimprovingthemodelingofwindprojectsfordetermining
thepotentialimpactsonsystemreliabilityduringtheprocessofevaluating
interconnectionapplicationsfromwindgenerators.
7/31/2019 AA WindModel
27/99
17
Intermsofwindintegrationcosts,theresultsofvariousstudiesconductedtodateintheUnited
Statesandoverseashavebeenreasonablyconsistent.Overall,thefindingscanbesummarized
asfollows:
Thecostforintegratingwindisnonzeroandincreasesastheproportionofwind
generation
to
conventional
generating
resources
or
peak
load
increases;
Reservecostsattributedtowindintegrationarerelativelysmallatwindpenetration
levelsoflessthan20percent.Howthevariabilityanduncertaintyofwindgeneration
interactswithvariationsinloadandloadforecastinguncertaintyhasalargeimpacton
thelevelofwindintegrationcosts.
Levelofgeographicconcentrationofwindprojectsalsoaffectswindintegrationcosts.
Unitcommitmentimpactshavebeenamajorfocusofwindintegrationstudiesinthe
UnitedStatesbuthavenotbeenaddressedasextensivelyintheEuropeanstudiesto
date.
BasedonseveralEuropeanstudiesthatestimatedthecostsofadditionalreserveswith
windgeneration,costsweregenerallylessthan$6/MWhatwindenergypenetrationlevelsupto20percent,althoughthecostsvariedsignificantlyamongtheindividual
studies.
Reservecostsforwindgenerationaredependentonthecharacteristicsofthegridthatis
integratingwind,theadequacyandcharacteristicsoftheexistingreserves,andthe
specificreserverequirementsforeachgrid.
StudiesestimatingthecapacitycreditofwindpowerinEuropedeterminedthatwind
hasacapacitycreditgreaterthanzero,andalsothatthecapacitycreditdecreasesasthe
levelofwindgenerationrises.
Factorsthat
affect
the
capacity
credit
of
wind
include
present
levels
of
wind
generation
onthegrid;thequalityofthewindresource;thecapacityfactorofthewindprojects;
whetherdemandandwindgenerationarecorrelatedoruncorrelated;thedegreeof
systemsecurity;andthestrengthofthetransmissioninterconnections.
Astimegoeson,moresimilaritiesthandifferencesareapparentbetweenEuropeandthe
UnitedStatesasvariablerenewableenergygenerationincreasesinmarketpenetration.These
similaritiesaresparkinginformationexchangeandtransferthroughforumssuchastheIEA,the
InstituteofElectricalandElectronicsEngineersandtheUtilityWindIntegrationGroup
(UWIG).That,inturn,canhelpelevateprominentissuesandmakethetaskofdeveloping
solutionsandoptionsforintegratingvariablerenewableenergygenerationeasier.
BenefitstoCaliforniaCaliforniahasperhapsthemostsignificantanddiverseRPSintheUnitedStatesintermsofthe
level(20percent),timeframe(2010)andtheamountofrenewableenergycapacitythatmaybe
requiredtomeetthetarget.Transmissionandtheintegrationofvariablerenewableenergy
generationremainchallengesthatneedtobeaddressedinorderforCaliforniatomeetitsRPS
goals.VariouscountriesinEuropehaveexperiencewithintegratinghighlevelsofvariable
7/31/2019 AA WindModel
28/99
18
renewableenergygeneration.Byreviewingandhighlightingstrategiesandpracticesthathave
beenusedtointegratewindinotherstatesandinothercountriesinthisreport,theIAPmay
incorporatesomeofthesestrategiesandpracticesasoptionstotestpotentialeffectivenessin
integratingvariablerenewableenergygenerationinthestate.ThehopeisthatCalifornia
projectsandutilitiescanbegintoevaluateandincorporatesomeoftheseapproachesandtotest
theireffectiveness
in
integrating
renewables.
7/31/2019 AA WindModel
29/99
19
1.0 Introduction
Growthinwindandsolarhasbeensurginginrecentyears.Windcapacityworldwideincreased
by25%in2006ascomparedto2005,andEuropereachedits2010goalof40,000MWinstalled
windcapacityfiveyearsearly(GlobalWindEnergyCouncil2006).Solarcellproductionhas
been
increasing
at
over
25%
annually,
and
shortages
in
materials
for
solar
cells
and
solar
cells
themselveshavebeenreported(EarthPolicyInstitute2004).
Withgrowthcomeconcernsoverhowtheelectricitygridwillintegratevariablerenewable
energyresourcessuchaswindandsolar.Thisreportreviewsthecurrentstudies,practiceand
experienceintegratingvariablerenewableenergygeneration.Theapproachforthispaperhas
beentoreviewnumerousreports,presentationsandconferencepapersandtofocusonissues
identifiedwithintegratingvariablerenewables.Foravarietyofreasons,thispaperwill
primarilyciteexamplesforwindgiven:
thereismoregridconnectedwindcapacityworldwidethansolar;
theexperience
with
wind
is
more
widely
reported;
and
thedevelopmenttodateofsolarsystemshasbeenpredominantlyofsmall,distributed
systemsand,atleastasofnow,doesnotfacethesamesystemintegrationissuesaswind
power.
Withanumberofincentiveprogramsforsolar,particularlyinGermanyandSpain,grid
connectedsolargenerationisstartingtoincrease.Ofthelargest20gridconnectedphotovoltaic
(PV)powerplantsintheworld,16havebeeninstalledin2004orlater(PVResources.com2006).
Twothirdsofthe74GWofworldwidewindcapacityislocatedinEurope,makingEuropean
interestingcasestudyforstudyingthegridimpactsofwind.Althoughwindprovidesabout3%
of
Europes
electricity,
some
regions
have
considerably
higher
wind
penetrations
as
indicated
in
Table1,suchasWesternDenmark(>20%)andSchleswigHolsteininGermany(~30%)
(Holttinen2004).Ultimately,someestimatesindicatethatwindmayprovide12%ofEuropes
electricitydemandby2020and30%by2030(VanHulle2005).
7/31/2019 AA WindModel
30/99
20
Table 1. Examples of wind power penetration levels, 2005
Country or region Installed wind
capacity
(MW)
Total installed
power capacity
(MW)
Average
annual
penetration
levela(%)
Peak
penetration
levelb
(%)
Western Denmark 3,128 7,488 ~23 >100Germany: 18,428 124,268 ~5 n.a.
Schleswig-Holstein 2,275 _________c ~28 >100
Spain 10,028 69,428 ~8 ~25%
Island systems:
Swedish island of
Gotlandd
90 No local generation
in normal state
~22 >100
n.a. = Not availableaWind energy production as share of system consumption
bLevel at high wind production and low energy demand, hence, if peak penetration level is >100%
excess energy is exported to other regions.cGerman coastal province
d2002 data. The island of Gotland has a network connection to the Swedish mainland.
Source: Adapted from Soder, Lennart and Ackerman, Thomas (2005). Wind Power in Power Systems: AnIntroduction, In T. Ackerman (Ed.), Wind Power in Power Systems(pp. 25-51). England: John Wiley andSons, Ltd. Updated and adapted by the author. Reproduced with permission.
ThemajorityofwinddevelopmentinEuropehastakenplaceinthreecountries:Denmark,
Germany,andSpain.Together,thosethreecountriesaccountfor50%ofworldwideinstalled
windcapacity.WinddevelopmentinDenmarkandGermanyhasconsistedofsmall
installationsofwindturbinesthatarewidelydistributed,takingadvantageofthegeographic
dispersion
of
wind
resources
and
providing
some
smoothing
of
winds
variability.
DenmarkandGermanyalsohavestronginterconnectionswithothercountries,allowingthe
exportofsurpluswindproductionandtheimportofpowerwhenwindproductionislow.
Morerecentwinddevelopmentinothercountrieshasoccurredwherethereislittleornogrid
interconnectionwithothercountries.ExamplesincludeSpain,Ireland,andBritain,where
internationalgridinterconnectionsaremorelimited.
AsonshorewinddevelopmentinEuropebecomesmoresaturated,winddevelopmentwill
likelymoveoffshoreandbemoreconcentratedinsmallergeographicareas.Over54GWof
offshorewindisinvariousstagesofplanninginEurope(LiebreichandYoung2005).In
Germanyalone,between25and30GWofoffshorewindcapacityisplannedfortheNorthand
BalticSeas
by
2030
(Deutsche
Energie
Agentur
2005).
Not
only
will
wind
capacity
be
more
concentrated,losingsomeofthesmoothingeffectsforwindfromgeographicdispersion,but
someoftheproposedoffshorewinddevelopmentisinregionsthatalreadyhavehighwind
penetration,suchasNorthernGermany,furtheraddingtotheintegrationchallenges.
AlthoughpresentoperatingpracticeshaveallowedEuropetomanagewindsvariability,there
issomethoughtthatnewstrategieswillbenecessarytoaccommodatethefuturegrowthof
7/31/2019 AA WindModel
31/99
21
wind.TheUnionfortheCoordinationofTransmissionofElectricity(UCTE),theassociationof
transmissionsystemoperatorsfrom23Europeancountries,issuedastatementinMay2005
callingformoregridinfrastructureandotheractionstointegratewindintheEuropeangrid
(UCTE2005).TheEuropeanWindEnergyAssociationalsoanticipatesthatsomechangesmay
benecessaryinoperatingthegridathigherlevelsofwindpenetration,andsuggestedthat
planningbegin
for
those
changes
(Van
Hulle
2005).
The
IEA
is
sponsoring
an
annex,
Design
andOperationofPowerSystemswithLargeAmountsofWindPowerProduction,thatbegan
inmid2006(InternationalEnergyAgency2006).Finally,theEuropeanTransmissionSystem
Operators(ETSO),theassociationoftransmissionsystemoperatorsinEurope,announcedplans
toconductaEuropewidewindintegrationstudy.Theplannedstudywillencompass16TSOs
in14countriesthatrepresentthefourmajorsynchronouselectricitygridsinEurope.Early
resultsfocusingonwindintegrationsolutionsineachsynchronousgridareexpectedin2008
(ETSO2006).
Thegridsituationisdifferentaswinddevelopmentspreadstoothercountriesaroundthe
world.India,forexample,doesnothaveanationalgridbutinsteadhasfivestateowned
regionalgrids,
with
the
grids
in
rural
areas
tending
to
be
weak.
Periodic
power
outages
in
India
arecommonandcauseupto$25billionineconomicdamagesannually,accordingtothe
governmentofIndia(Sieg2006).Indiahasmovedintofourthplaceamongcountrieswiththe
mostinstalledwindcapacityandmetits2012targetof5,000MWofwindcapacityin2006
(RajgorandMathews2006).Similarly,Chinasexplosiveeconomicgrowthhasexceeded
availableelectricitysuppliesandledtoelectricityshortages,withtwothirdsoftheprovincesin
Chinaexperiencingblackoutsin2004(Kuetal.undated).Chinahasabout2,600MWofwind
capacityandhassetagoalof30GWofwindby2020(Jianxiang2006).WindprojectsinChina
mustmeeta50%localcontentstandardforprojectsapprovedbefore2005,increasingto70%for
projectsapprovedafter2005.
Theparticularcircumstancesineachcountry,stateorregionwilldeterminetheeaseof
integratingvariablerenewableenergygeneration.Amongotherthings,thisincludessuch
factorsaswhetherthegeneratingmixhasflexibleresourcesornot;whethertherearewell
functioninganddeephouraheadanddayaheadmarkets;whetherthewindprojectsare
relativelyspreadoutorconcentrated;whetherthereisavailabletransmission;andwhetherthe
controlareasarefairlybroadorrelativelysmall.Becausethesecircumstancescanvary
dramatically,cautionshouldbeusedincomparingcountriesorregionswitheachother.Wind
integrationwillalmostcertainlybemorechallenginginsmallcontrolareas,inareaswithnot
muchinterconnections,orinareaswithasmallloadand/orsmallresourcestackascomparedto
regionswithlargercontrolareas,extensiveinterconnectionsorlargeloadsand/ordeepresource
stacks.Some
of
the
more
stringent
wind
control
strategies
have
been
proposed
in
countries
that
havelittleornogridinterconnections,andtheseparticularcircumstancesneedtobekeptin
mindwhencomparinginternationalwindintegrationexperiences.
Thatsaid,theinternationalexperiencewithwindofferssomelessonsforregionsintheUnited
Statesthathaveorareexpectingsignificantadditionsofwindcapacity.Already,somecountries
havedevelopedwindforecastingstrategiesandgridcodesaddressingwindpowersystemsthat
haveformedthebasisforsimilaractionsintheUnitedStates.Thattrendislikelytocontinue.
7/31/2019 AA WindModel
32/99
22
Moreexperiencewithwindintegrationwillbegainedascountriesaddwindtotheirgenerating
mix.
Thereportisorganizedasfollows.Theremainderofthischapterprovidesanoverviewof
worldwidewindandsolarcapacity.Chapter2reviewstheresultsofwindintegrationstudies
and
practices
in
the
United
States
and
Europe.
Chapter
3
discusses
the
effects
of
market
structureandreviewshowthecapacitycreditofwindisdeterminedinternationallyandinthe
UnitedStates.Chapter4describesgridoperationissueswithwindtodate.Chapter5reviews
thesolutionsthatgridoperatorshavedevelopedtohandlethevariabilityofwindgeneration.
Chapter6presentssomefindingsandimplicationsforCalifornia,whileChapter7provides
conclusions.Countryspecificprofilesareofferedintheappendixonfourofthefiveleading
countriesintheworldinregardstoinstalledwindcapacity:Germany,Spain,India,and
Denmark.(TheUnitedStatesistheotherleadingcountryininstalledwindcapacity.)
1.1. Worldwide Wind and Solar Capacity
Windpowergenerationhasbeenrapidlygrowinginpowersystemsthroughouttheworld.
Table2showsglobalwindenergygeneratingcapacityattheendof2006,aswellaswindcapacityadditionsin2006.AmajorityofthewindpowercapacityhasbeeninstalledinWestern
Europe,specificallyinDenmark,GermanyandSpain;however,emergingwindenergy
contributorsincludeIndia,Japan,andChina.Indeed,IndiasurpassedDenmarkin2005asthe
fourthleadingcountryininstalledwindcapacity(GWEC2006).
Worldwidesolarinstallationsarealsosurging,with1,460MWinstalledin2005(seeFigure1).
Germanyaccountedfor837MWofthistotal,representing57%ofthemarket.Overall,installed
solargeneratingcapacityexceeds5GWworldwide,andprojectionsarethatannualsolar
installationswillincreasetobetween3,200MWand3,900MWby2010(Solarbuzz2006).
Table3presents
the
twenty
largest
solar
grid
connected
projects
in
the
world.
Of
these
twenty,
onlyfourwereinstalledbefore2004.Largescalesolarthermalconcentratingprojectsare
beginningtoappearaswell,withSpainplanning795MWofparabolictroughandpowertower
projects(WesternGovernorsAssociation2006).
7/31/2019 AA WindModel
33/99
23
Table 2. Global wind energy capacity by country, 2006
Country
2006
Capacity Additions
(MW)
2006 Total
Installed Capacity
(MW)
Germany 2,233 20,622
Spain 1,587 11,615Denmark 12 3,136Italy 417 2,123UK 634 1,963Portugal 694 1,716France 810 1,567Netherlands 356 1,560
Austria 146 965Greece 173 746Ireland 250 745Sweden 62 572Norway 47 314Belgium 26 193Poland 69 153Other (1) 192 556Europe Total 7,708 48,545
United States 2,454 11,603Canada 776 1,459North America 3,230 13,062
India 1,840 6,270China 1,347 2,604Japan 333 1,394Taiwan 84 188
South Korea 75 173Philippines 0 25Other (2) 0 13Asia 3,679 10,667
Australia 109 817New Zealand 3 171Pacific Islands 0 12Total Pacific Region 112 1,000
Brazil 208 237Mexico 85 88Costa Rica 3 74
Caribbean (w/o Jamaica) 0 35Argentina 0 27Columbia 0 20Jamaica 0 20Other (3) 0 7Latin America 296 508
7/31/2019 AA WindModel
34/99
24
Table 2: Global wind energy capacity by country, 2006 (continued)
Country
2006
Capacity Additions
(MW)
2006 Total
Installed Capacity
(MW)Egypt 85 230Morocco 60 124Iran 27 48Tunisia 0 20Other (4) 0 11Africa & Middle East 172 433
World Total 15,197 74,215
(1) Bulgaria, Croatia, Cyprus, Czech Republic, Estonia, Finland, Faroe Islands, Hungary, Iceland,Latvia, Liechtenstein, Lithuania, Luxembourg, Malta, Romania, Slovakia, Slovenia, Switzerland, Turkey,Ukraine.
(2) Bangladesh, Indonesia, Sri Lanka, Russia;
(3) Chile, Cuba, Mexico.
(4) Cape Verde, Israel, Jordan, Nigeria, South Africa
Source: Global Wind Energy Council Press Release. Global Wind Energy Markets Continue To Boom 2006 Another Record Year. February 2007. Available at http://www.gwec.net/uploads/media/07-02_PR_Global_Statistics_2006.pdf
Figure 1: Worldwide PV installations in 2005 (MW)Source: 2006 World PV Industry Report Highlights: World Solar Market. Up 34% in2005; 837 MW Installed in Germany. Solarbuzz LLC, March 15, 2006. Available athttp://www.solarbuzz.com/Marketbuzz2006-intro.htm.
7/31/2019 AA WindModel
35/99
25
Table 3. Twenty largest grid-connected photovoltaic systems
World
Rank
Project Location Size
(MW)
Date Installed
1 Solarpark Pocking Pocking, Germany 10 April 2006
2 Solarpark Muhlhausen Muhlhausen, Germany 6.3 December 2004
3 Freiland SonnenStrom Miegersbach, Germany 5.27 Part 1, June 2005
Part 2, December2005
4 Burstadt Plant Burstadt, Germany 5 February 2005
5 Solarpark Leipziger Land Espenhain, Germany 5 August 2004
6 Springerville Generating
Station
Tuscon, Arizona, USA 4.59 2001-2004
7 Solarpark Saarbrucken Saarbrucken, Germany 4 Part 1, June 2004
Part 2, September
2005
Part 3, December
2005
8 Solarpark
Geiseltalsee/Merseburg
Geiseltalsee/Merseburg,
Germany
4 September 2004
9 Solarpark Zeche Gottelborn
(Part 1)
Gottelborn, Germany 4 August 2004
10 Solarpark Hemau Hemau, Germany 4 2003
11 Fischers Family Warehouse Kronwieden/Dingolfing,
Germany
3.7 October 2005
12 Michelin Reifenwerke KGaA Homburg, Germany 3.5 December 2004,
expanded June
2005
13 Solarpark Penzing Penzing, Germany 3.45 December 2005
14 Co.Muckenhausen roof
mounted plant
Dingolfing, Germany 3.3 October 2004
15 Centrale di Serre Persano,
ENEL research center
Serre, Italy 3.3 1995
16 Castejon power plant Castejon, Navarre, Spain 2.44 February 2006
17 Solarpark Hofkirchen, part of
Solarpark Donau
Hofkirchen, Germany 2.37 August 2005
18 Solaranlage Darast Nord Bad Gronenbach/Woringen,
Germany
2.3 November 2005
19 Floriade exhibition hall PVSystem
Vijfhuizen, Netherlands 2.3 April 2002
20 Michelin Reifenwerke KGaA Bad Kreuznach, Germany 2.2 2005
Source: Worlds Largest Photovoltaic Power Plants, pvresources.com. Accessed June 2006.
Available at http:///www.pvresources.com/en/top50pv.php
7/31/2019 AA WindModel
36/99
26
7/31/2019 AA WindModel
37/99
27
2.0 Wind Integration Studies in the United States andWorldwide
ThischapterwillreviewthewindintegrationstudiesthathavebeenconductedintheUnited
Statesandinvariouscountriesaroundtheworld.Thesestudiesoftenemphasizetheroleof
ancillaryservices
and
the
impact
of
wind
power
on
the
need
for
and
availability
of
these
services.WewillbeginbyexamininghowancillaryservicesaredefinedinEuropeandinthe
UnitedStates.
Electricpowersystemsneedavarietyofancillaryservicestomaintaingridoperationand
reliability.Thereisnotgeneralagreementonhowtheseservicesaredefined,andasexplained
furtherbelow,theUnitedStatesandEuropedefinetheseservicesdifferently.Evenwithinthe
UnitedStates,theremaybedifferencesinwhatisconsideredancillaryservices.Ingeneral,
though,thefollowingareconsiderednecessarytomaintainreliablegridoperation:
RegulationMaintainingsystemfrequencythroughvaryingcertaingeneratingunits,
typically
with
automatic
generation
control
(AGC),
up
and
down
in
response
to
very
fast,unexpectedchangesinloadandgeneration.
LoadFollowingRampinggenerationupordowntoreacttothechangeinexpectedload
patterns,suchasincreasingloadsinthemorninganddecreasingloadslateintheday.
SpinningReserveGeneratingcapacity,typicallysynchronizedtothegrid,thatcan
maintainreliabilityifageneratingunitortransmissionlineistrippedoffline.
SupplementalreservesThisperformsasimilarfunctiontospinningreserves,i.e.,
maintainingreliabilityincaseofthelossofamajorgeneratingunitortransmissionline,
butthegeneratorsprovidingthisservicearenotgenerallysynchronized(nonspinning)
tothegridandmayneedadditionalstartuptimetocontribute.Insomeinstances,
supplementalreserves
may
also
replace
spinning
reserves
after
aperiod
of
time
(Zavadil,etal.2006). Regulationandloadfollowingarereservesusedfornormal
systemconditions,whilespinningandsupplementalreservesareusedforcontingency
conditions.
EuropeandtheUnitedStatesusedifferentterminologyindescribingthesevariousancillary
services(Table4).InEurope,primaryreservesassistwiththeshortterm,minutetominute
balancingandcontrolofthepowersystemfrequency,andareequivalentintheUnitedStatesto
regulation.Primaryreservesmustbeavailablewithinsecondsandistypicallydoneby
synchronousgeneratorsthatwillautomaticallyincreaseproductionwhenfrequencydropsor
reduceproductionwhenfrequencyincreases,orfromloadthatcanbedroppedorreduced.
Usually,the
amount
of
primary
reserve
is
defined
by
the
largest
power
plant
that
can
be
lost
whilemaintaininggridreliability.SecondaryreservesinEuropetakeoverforprimaryreserves
10to30minuteslater,freeingupcapacitytobeusedasprimaryreserves.Sourcesforsecondary
reservesincludequickstartgasturbines,pumpedstoragehydroprojectsandloadreductionor
shedding.Likeprimaryreserves,secondaryreservesmayequalthelargestgeneratingunit,
althoughafactormaybeaddedtoaccountforloadforecasterrors(HolttinenandHirvonen
7/31/2019 AA WindModel
38/99
28
2005).TheclosestterminologyintheUnitedStatesforsecondaryreservesiseitheroperating
reservesorloadfollowingreserves,whichmayincludebothspinningandnonspinning
components.LongertermreservesinEuropearecalledtertiaryreservesandareavailableinthe
periodsaftersecondaryreserves.Tertiaryreservesareclosesttosupplementalreservesinthe
UnitedStates,althoughthetimescalesmaybedifferentbetweenEuropeandtheUnitedStates.
Theterms
primary
and
secondary
reserves
will
be
used
when
describing
the
international
experiencewithintegratingvariablerenewableenergygeneration.
Inadditiontousingdifferentterminology,EuropeandtheUnitedStatesusedifferent
frequenciesfortheelectricgrid.Europeoperatesat50HzandtheUnitedStatesoperatesat60
HZ.
Table 4. Reserve definitions in Germany, Ireland, and the United States
Short-term
reserves
Medium-term
Reserves
Long-term
reserves
Germany Primary reserve:
available within 30seconds, released by
transmission system
operator
Secondary reserve:
available within 5minutes, released
by transmission
system operator
Minute reserve:
available within 15minutes, called by
transmission
system operator
from supplier
n/a
Ireland Primary operating
reserve: available
within 15 seconds
(inertial response/
fast response)
Secondary
operating reserve:
operates over
timeframe of 15-90
seconds
Tertiary response:
from 90 seconds
onwards (dynamic
or static reserve)
n/a
United States Regulation horizon: 1
minute to 1 hour with1- to 5-second
Load-following horizons: 1 hour within
increments 5- to 10 -minute increments(intra-hour) and several hours (inter-hour)
Unit-
commitmenthorizon: 1 day
to 1 week with
1-hour time
increments
Source: Gul, T. and Stenzel, T. 2005. Variability of Wind Power and Other Renewables: Management Optionsand Strategies. Paris: International Energy Agency.
FourelectricallysynchronouszonesarepresentinEurope:theNordiccountries,theUCTE
countries,GreatBritain,andIreland.
TheNordic
synchronous
zone
serves
Finland,
Sweden,
Norway,
and
Eastern
Denmark.
Overall,25millionpeopleareserved,andabout90GWofgeneratingcapacityislocated
inthiszone.Thetransmissionsystemoperatorshaveorganizedacooperativebody
knownasNordelforadministeringtheNordicelectricitymarket.Totalprimarycontrol
reserveis1,600MW,consistingofoperatingreservesof600MWandadisturbance
reserveof1,000MW.
7/31/2019 AA WindModel
39/99
29
TheUCTEzoneservesabout500millionpeoplein23countries,withabout603GWof
generatingcapacitylocatedinUCTE.ForUCTE,primaryreservesmustbeactivated
within30secondsandcoverthelossofupto3,000MWofproduction.
TheNationalGridCompanyisthegridoperatoroftheelectricitygridinEngland,Wales
andScotland.About81GWofgeneratingcapacityislocatedinGreatBritain,with
interconnectionsto
France
(2,000
MW)
and
Northern
Ireland
(450
MW)
and
requires
reservestocoverthelossof1,320MW.
TwoTSOs,theEirGridandtheSystemOperatorsNorthernIreland,administerthegrid
inIreland,withageneratingcapacityof7,600MWa