MassiveTransientStabilityBasedCascadingAnalysisandOn-lineIdentificationofCriticalCascades

PaperNumber:16PESGM2419MariannaVaiman,V&REnergymarvaiman@vrenergy.com

2016IEEEPESGeneralMeeting,Boston,MACFWGPanelSession“CascadingOutages- Dynamics,

Protection,ValidationandData”July20,2016

1

Contents:

2

1. MassiveTransientStabilityBasedCascadingAnalysis

2. On-LineIdentificationofCriticalCascades

3

1. MassiveTransientStabilityBasedCascadingAnalysis

2015CWFGSurveyWhatwouldmakeyoumoresatisfied/Arethereanycomputationsassociatedwithcascadingoutagesyoufeelpresenttoolsfailtoaddress?• Dynamicsimulationofcascadingoutageswhichshouldincludeprotection

systemmodeling• Bettersolutionalgorithms/robusttools• Automated/optimizedmitigationmeasures• Identifyingandclassifyingwidespreadsystemarealimitationversuslocalarea

limitation• Identifyingandquantifyingtheriskofcomplicatedcascadesandlargeblackoutsin

awaythatallowstheseriskstobemonitoredandmitigated• Havingascreeningtool• Wideareavisualizationandanalysistoolsthatcanidentifystressindicatorsearly

andhelpoperatorstakeappropriateactions

4

NERCStandardsRelatedtoCascading• PRC-002-2—DisturbanceMonitoringandReportingRequirements• TPL-001-4— TransmissionSystemPlanningPerformanceRequirements• CIP-014-2— PhysicalSecurity• CIP-002-5.1—CyberSecurity—BESCyberSystemCategorization• PRC-023-2—TransmissionRelayLoadability• PRC-024-1—GeneratorFrequencyandVoltageProtectiveRelaySettings• EOP-002-3.1—CapacityandEnergyEmergencies• EOP-003-2—LoadSheddingPlans• TOP-001-2— TransmissionOperations• TOP-004-2— TransmissionOperations• FAC-003-3—TransmissionVegetationManagement• FAC-011-2—SystemOperatingLimitsMethodologyfortheOperationsHorizon• IRO-008-1—ReliabilityCoordinatorOperationalAnalysesandReal-time

Assessments• IRO-010-1a—ReliabilityCoordinatorDataSpecificationandCollection

AnApproachtoTransientStabilityBasedCascadingAnalysis

• ImplementedinPotentialCascadingModes– TransientStability(PCM-TS)application:– Analyzescascadingoutagesfromtransientstabilityperspectivewhile

consideringprotectionsystem– UsedtoaddressNERCTPL-001-4standard

• Addressesthefollowingaspectsofassessmentofcascadingoutages:– Initiatingevents– three-phase&unbalancedfaults,anduser-defined

switchingsequences– Considersgeneratorout-of-stepconditions,overloads,transientvoltage

deviation– Incorporatesprotectionsystemmodeling

6

ACascadingEventfromTransientStabilityPerspective

• Aneventisclassifiedasacascadingoutageifatleastoneoftheconditionsismet:– Sharpdropintransientvoltages

inalargepartofthenetwork– Sharpdropinfrequencyfollowed

bysystemseparation– Islandsareformedasaresultof

protectionoperation,withsignificantamountofload/generationwithintheisland

– Disconnectionoflargeamountofgeneration– Disconnectionoflargeamountofload

7

Time-DomainSimulationduringCascadingAnalysis

• Eachcascadingeventissimulatedusingtimedomainsimulation:– Associatedtimeconstantsarespecifiedas

theuserinput

• Duringacascadingevent,elementsarebeingtripped.Trippedelementsmaybelines,transformers,loads,andgenerators

8

CriticalCascadeCriteria• Time-domainsimulationrunsuntilatleast

oneoftheCriticalCascadecriteriaismet:– Islanding

TotalMWofloadinallcreatedislands,exceptthelargestislandexceedsapre-definedthreshold

– InterfacelimitviolationInterfaceMWflowduringcascadeexceedsinterfacelimit

– MWloadlossTotalMWlossofloadtrippedduringcascadeexceedsapre-definedthreshold

– MWgenerationlossTotalMWlossofgenerationexceedsapre-definedthreshold

– CascadepropagationCascadepropagatesbeyondtheuser-definedcontrolarea(s)

9

GeneratorAngleDeviation• Checksthemaximumchangeintherotorangledeviation

• Computesthedifferencebetweenmaximumandminimumgeneratorrotorangles,anddeterminesthemaximumdifference:– Computedduringuser-definedtimeinterval– Unitswithsmallerrealpoweroutputmaybeexcludedfrommonitoring

• Doneforinformationalpurposesonly;thisisnotincludedinCriticalCascadecriteria

10

CheckingSteady-StateStability• Aftertime-domaincomputationiscompleted,allelementstrippedasaresultofacascadingchain,aretrippedusingsteady-state(e.g.,loadflow)computation

• Powerflowsolutionisobtained

11

CriticalTrippingCriteriaandDelays• Trippingoccursduringacascadingevent

ifatleastoneofthetrippingcriteriaismet:– Linetrippingthreshold– Transformertrippingthreshold– Loadtrippingthreshold– Generatortrippingthresholds

• ElementTrippingandDelays:– TrippingoccursonlyifacriterioncontinuestobemetduringRelayDelay

timeinterval– Inthiscase,theelementwillbetrippedafterRelayDelaytimeinterval

elapsed

12

ModelingRelayOperation• Fourtypesofrelaysconsideredduring

theanalysis:– Distancerelays– Overcurrentrelays– Undervoltage relays– Underfequencyrelay

• Itisassumedthattheaboverelaysareinstalledonalllines,transformers,loads,andgenerators

• Relayoperationismodeledusingtheuser-defineddelays

13

TypesofCascadingOutcomes• Basedondeterminationandcomparisonofdampingparameters

14

Outcome OutcomeType1 Decreasingamplitudeoscillations2 Increasingamplitudeoscillations3 Oscillationswithdecreasing frequency4 Oscillationswithincreasing frequency5 Monotonouslyincreasing frequency6 Monotonouslydecreasing frequency

ResultsofMassiveCascadingAnalysis• Detailedandsummarized

resultsofcascadinganalysisareproduced

15

16

2. On-LineIdentificationofCriticalCascades

On-LineCascadingAnalysis• Steady-stateanalysisoffastdevelopingcascadingeventswhen

Operatorhasnotimetoreact• Usesnode-breakermodelofthesystem:

– SCADA-basedState-EstimatorcasesorPMU-basedLinearStateEstimatorCases

• InitiatingEventsarecomplexcontingencies(N-2,stuckbreaker)beyondN-1whichareaddressedinregulardispatch

• ClassifieseveryInitiatingEventasCritical,NearcriticalorAcceptable:– Basedonoperationalreliabilitycriteriaappliedtoconsequencesofpotential

cascade

• ImplementedinROSE/PCMtool

17

IdentificationofaCriticalCascade• Purpose:classificationofCascadeasCriticalistheidentificationof

IROLviolationbasedonmeasurableconsequences• ExistenceofaCriticalCascadelongerthan30minutesmeansIROL

violationreportableevent• ConceptofCriticalCascadeisaconsistent,quantifiableand

auditableprocessofIROLviolationanalysis• ConceptofCriticalCascadeisapracticalinstrumenttosatisfy

genericNERCrequirementsofIROLcompliance

18

Source:ISONEandV&REnergy

AttributesofaCriticalCascade• CriticalCascadesatisfiesatleastoneofthefollowingcriteria:

– Systemwidevoltagecollapseoccursuponapplyinginitiatingcontingencyorastheresultofcascadingtripping

– IslandingofthesystemandtotalMWofloadinseparatedislandsisgreaterthanpre-definedthreshold

– ActualinterfaceMWflowduringcascadeexceeds“stability”interfacelimitbypre-defined%level

– TotalMWlossofloadexceedspre-definedthreshold– TotalMWlossofgenerationexceedspre-definedthreshold– CascadepropagatesbeyondBalancingAreafootprint

• EachcriterionforaCriticalCascadeisconfigurable:– Enable/Disable– Thresholdvalue

19

DataFlowforOn-LineAnalysis20

Source:SlavaMaslennikov,EugeneLitvinov,ISONE

ProcessofOn-LineCascadingAnalysis21

Source:SlavaMaslennikov,EugeneLitvinov,ISONE

On-lineROSE-PCMGUI22

Source:SlavaMaslennikov,EugeneLitvinov,ISONE

MetricsofLocalityofVoltageCollapse• Non-convergenceofpowerflowisreportedas“voltageinstability”.

– Majority(>90%)of“voltageinstability”haslocalimpactandaffectsquitelimitedMWofloads

– Typicalpowerflowsolutioncannotdistinguish“local”from“widespread”voltageinstability

• “Locality”ofvoltagecollapseismeasuredbytheminimalMWofloadsheddingnecessarytopreventvoltagecollapse

23

Source:SlavaMaslennikov,EugeneLitvinov,ISONE

Thankyou!24