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Transientstabilitymodelingusinghighlydetailedsyntheticelectricgridswithdistributionsystemapplications

TomOverbye,AdamBirchfield,TiXuTexasA&MUniversity

Overbye@tamu.edu,birchfieldllc@gmail.comAugust6,2019

TiXu,1988-2018•  SomeoftheworkpresentedherewasdonebymyformergraduatestudentandpostdocTiXu

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Introduction•  Ourmodernsocietydependsonreliableelectricity;largeblackoutscanbecatastrophic

•  Interconnectedelectricgridsworld-wideareinaperiodofrapidtransition,withmuchofitatthedistributionleveland/orimpactinggriddynamics–  Changingloadandgeneration,customerswithchoiceintheirelectricservice,inclusionofnewtechnologies

•  Therearelotsofopportunitiesforinnovation!

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DataandModelAccessBarriers•  Inmanyplacesworldwideaccesstodataabouttheactualpowergridisrestrictedbecauseofneedsforconfidentiality(e.g.,inUSCEII)–  DataandmodelsaresometimesavailablethroughNDAs,butabilitytopublishanddistributedislimited

•  Todoeffectiveresearchresearchersneedaccesstocommon,realisticgridmodelsanddatasets

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Solution:SyntheticElectricGrids•  Syntheticelectricgridsarefictionalrepresentationsthatarefreefromconfidentialinformation

•  OverthelastthreeyearstremendousprogresshasbeenmadethroughtheU.S.ARPA-Eincreatinglarge-scale,highquality,syntheticgridsatboththetransmissionanddistributionlevels

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Solution:SyntheticElectricGrids•  Validationwithactualelectricgridsanddatasetshasbeenacrucialcomponentofthisresearch

•  Goalisthatinnovationdonewiththesegridscanbedirectlyappliedtotheactualgrid

•  Talkfocusesonrecentworkoncombinedtransmissionanddistributionsystemmodelswithdynamics

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ElectricGridTimeFrames7

Image source: P.W. Sauer, M.A. Pai, Power System Dynamics and Stability, 1997, Fig 1.2, modified

OurSyntheticGridApproach•  Makegridsthatlookrealandfamiliarbysitingthemgeographically(NorthAmericaforus)andservingapopulationdensitythemimicsactual

•  Goalistoleveragewidelyavailablepublicdata–  Geographyandpopulationdensitynowdowntotheparcel–  Loadbyutility(USFERC714),state-wideaverages–  Existingandplannedgeneration(FormUSEIA-860,whichcontainslotsofgeneratorinformation)

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SyntheticModelDesignProcess9

The assumed peak load is based on population, scaled by geographic values

Much of this is automated, but there is still some manual adjustment

CurrentStatus:Transmission10

This is an 82,000 bus synthetic model that we publicly released in summer 2018 at electricgrids.engr.tamu.edu

Substation locations and the transmission system is entirely fictional (“realistic but not real”). Grid has an ac power flow solution with n-1 reliability

TheseGridsAlsohaveDynamicModels•  ThisslidesshowsthefrequencyresponseofourUSWesterngridtoadoublegeneratoroutage;atfirstglanceitlooksliketheWECC

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GridDynamics12

Theseresultswerecreatedusinga70Kbussystemwithdetaileddynamicmodelsfor8000generators.Themodelsandallthedataassociatedwiththisimagearepublic

Thegridmodelisavailableatelectricgrids.engr.tamu.edu

MovingDowntotheIndividualMeters•  Ourinitialworkstoppedatthe69kVlevel,andwasgeographicallyrealistictothezipcodelevel

•  Ournewwork,partneringwithNREL,istocombinetransmissionmodelswithdistributionsystemmodelsthatsupplyelectricmeterslocatedatactualparcels

•  Theresultantdistributionsystemstendtobequitegeographicallyrealistic

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Example:TravisCounty,TX14

This is a synthetic grid, but utilizing a quite realistic layout; blue is 230 kV, light green 69 kV, and lots of distribution lines down to hundreds of thousands of electric meters. This fall we will be doing all of Texas with about 10 million meters.

DistributionLevelDynamics•  Theprimarydistributionleveltransientstabilitytimeframedynamicscomefromtheloadandthedistributedenergyresources(DERs)–  Newmodelshavebeenintroducetorepresentvariousdistributiondrivendynamics

–  ThecompositionandhencethedynamicsoftheloadandDERscanbehighlytime-varying

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CombinedTransmissionandDistribution•  Withcompletemodelswecanstudywantpartsthesystemneedtobemodeledandatwhatdetail.Forexample–  Transmissiononly–  Distributiononly–  Fullelectricalmodelsfortransmissionanddistribution–  Fulltransmissionwithdetaileddistributiontopologyonlybutincludingattributeslikewhetheraparcelhaspv

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DevelopingTime-VaryingDynamics•  Ourapproachtodevelopingtime-varyingdynamicsmodelsinthedistributionsystemistoassignattributestotheindividualelectricmetersandthendevelopthedynamicmodelsbottom-up.–  Forexample,somemetershavePV;howmuchisondependsonsolarirradianceatthelocation;somehaveairconditioningwithamountdependentonambientconditions;somehaveelectricvehicles,etc.

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WhereWeAreGoing•  Wearedevelopingasetoftime-varyingscenariosinwhichpotentialgridsofthefuturecanbetestedunderawide-varietyofdifferentconditions–  Theywillbedrivenbytransientstabilityleveldynamicmodelsincludingdistributionleveldynamics

•  Theenvironmentwillalsoallowteamstooperateanelectricgridunderawidevarietyofconditions

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TexasA&MControlRoomLaboratory19

•  Thesimulationwillalsoallowforthetestingofdifferentpowersystemvisualizations

ThankYou!20

Questions?