PowerQualityAssessmentandItsOutlooksforFurtherResearch

XiaoXiangning

NorthChinaElectricPowerUniversity,China

September15,10:40-11:10

CICED2023,Nanjing,12-16day;developmentofthepowersupplysystemformoreintelligentContentsBackgroundsVoltagesagsassessmentExtensiveVoltageSagCharacteristicsAssessedPowerQualityEconomicsCorrectedReliabilityIndicesbasedonEconomicsVoltagedeviationassessmentReasonableAssessmentInteractionBetweenDERandQualityAssessmentOutlooksforpowerqualityassessmentConclusionBackgroundSmartGridResearchisbecomingafocusingissue.BackgroundVoltagesagsDeviationsOutlooksConclusionSmartGridinChinaCanAchieve10.5BillionTonsofCarbonEmissionReductionovertheNextDecadeStrongSmartGrid—inChinaBackgroundsAfteranalyzingtotheadverseimpactionofSG,anexpertofPQstandardizationinUSA,prof.McEachernsaidiftheresearchworknottodoonPQproblemssametimes,smartgridwillmakepowerqualityworse,notbetter.Powerqualitycontrolshouldberegardedasaimportantpartofsmartgrid.ButthebenefitsofSGaregreat,soitshouldcontinue…

BackgroundsApowerqualitydisturbancecanbedefinedasadeviationfromtheideal(sinusoidal,constantmagnitude)voltageorcurrent.Basedonthemonitoreddataorsimulateddataofpowersystemoperatingparameters,powerqualityassessment,whichisaveryimportantpartofpowerqualityresearcharea,isaprocessofcalculatingthequalityindicesandcheckingwhetherthevaluesfulfillthestandardlimitation,orwhetherthepowerdisturbancesmakeequipmentsmiss-function.

BackgroundVoltagesagsDeviationsOutlooksConclusionBackgroundsThepowerqualitystandardsshouldbeimprovedonthebasisoffurtherresearch,thoughasetofusefulstandardshavebeenpublished.Thechangesofpowerloadconstitution,thedevelopmentofdistributedgenerators,andtheintegrationoflargescalenewsources,resultedfromtheconstructionofSmartGrid,willintroducechallengesandopportunitiesfornewsufficientimportantandinterestingresearchinthedomainofpowerquality.

BackgroundVoltagesagsDeviationsOutlooksConclusionExtensive

Voltage

Sag

Characteristics

AssessedVoltagesagsare,accordingtostandards,characterizedbyonemagnitudeandoneduration.Otherindicesarestillindispute.IEC61000-4-30,IEC61000-2-2（12,8),IEC61000-4-11(34)IEEEstd493,IEEEstd1346

CIGREC4.07SEMI47EN50160NRS048

buttherearemanynewindicesarediscussedandstudiedinBackgroundVoltagesagsDeviationsOutlooksConclusionExtensive

Voltage

Sag

Characteristics

AssessedFromtheviewofinfluencedequipment,manufacturers,aswellaspowersuppliers,shouldbeawareofmorecharacteristicsthanjustmagnitudeandduration.BackgroundVoltagesagsDeviationsOutlooksConclusionExtensive

Voltage

Sag

Characteristics

AssessedCIGRE/CIRED/UIEJointWorkingGroupC4.110——VoltageDipImmunityofEquipmentandInstallations(2023.04)Forcharacterizingdipimmunityofthree-phaseequipment,voltage-tolerancecurvesshouldbegivenforthreegeneraldiptypes:TypeI,TypeIIandTypeIIIdips.BackgroundVoltagesagsDeviationsOutlooksConclusionPowerqualityeconomics--sagsTheeconomiccostassessmentofpowerqualityandtheprofitandlossanalysisofpowerqualityinvestmenthavecontributedtothedevelopmentofpowerqualityindustryandpowerqualityeconomics.CIGREJWGC4.107--EconomicFrameworkforVoltageQualityProposeastandardizedmethodofcollectinginformation,basedontheexperienceofvariousinternationalstudies.Recommendamethodologyofusingthesedatatocostandmotivatepowerqualityinterventionsonthepowersystemorwithinthecustomerplant.Provideindicativecostsforspecificindustrysectors,wherepossible.Providedetailthemainfactorsinfluencingdecisionsabouttheinvestmentinincreasedimmunityofequipment.VoltagesagsarethemostconcernedvoltagequalitydisturbancesandEconomicsonsagsisacriticalstudybecausethecostsareverysignificant.BackgroundVoltagesagsDeviationsOutlooksConclusionE.g.Costofdowntimeisdependentonmanyfactors.Voltagedippatternwithtimeoftheday.varyingcustomersizeinannualkWhconsumptionvaryingseasonandtimeofdayvaryingbusinesstypeCorrectedreliabilityindicesbasedoneconomicsBesidessustainedinterruptions,voltagesagsandshort-durationinterruptionsdisturbthecontinuousoperationofcustomersespecially,oftypicalcontinuousmanufacturingplants.SAIDI——theaverageinterruptiondurationofthecustomersservedSASDI——Averagesageconomicequivalentinterruptionduration

BackgroundVoltagesagsdeviationsoutlooksConclusionExampleofacontourchart:HV/MVsites(CP95value)CustomerSagFrequency——thenumberofsageventsforthecustomerperyearCSF(Vs=80%,T=100ms,Type=TypeIII)=35peryearTypeITypeIITypeIIIImmunityCurveCorrectedreliabilityindicesbasedoneconomicsThedefinitionofcorrectedreliabilitycomprehensiveindexASAI*(RS*)

SAIDIandSASDIarecoordinateoftheeconomiclossesofcustomersimpactedbysustainedinterruptions,short-durationinterruptionsandvoltagesags.BackgroundVoltagesagsdeviationsoutlooksConclusionVoltagesagassessmentTheprocedureforobtainingthecorrectedreliabilityindicesMainfourfactorsforassessmentDealwithTimeAggregationDealwithPhaseAggregationCalculationofDefinedindicesandcheckwiththespecifiedobjectsProcedureVoltagedeviationassessmentIEC61000-4-30:2023IEC61000-4-30supportspowerqualitymeasurementmethods.Thenewedition2023cancelsandreplacesthefirsteditionpublishedin2023.Measurement

Aggregation

BackgroundVoltagesagsdeviationsoutlooksConclusionThe10/12-cycler.m.s.valueshallbeused.Underdeviation150/180cycleand10minaggregationareperformedusingthesquarerootofthearithmeticmeanofthesquaredinputvalues.OverdeviationUnderdeviationOverdeviationVoltagedeviationassessmentIEC--AssessmentIndicessuggested–thenumber,orpercent,ofvaluesduringthemeasurementintervalthatexceedhighorlowcontractualvaluesmightbecounted;–theworst-casevaluesmightbecomparedtohighand/orlowcontractualvalues(themeasurementintervalmightbedifferentforthispossibility);–oneormore95%(orotherpercentage)probabilityweeklyvalues,expressedinvolts,mightbecomparedtohighand/orlowcontractualvalues;–thenumberofconsecutivevaluesthatexceedhighand/orlowcontractualvaluesmightbecounted.

BackgroundVoltagesagsDeviationsOutlooksConclusionVoltagedeviationassessmentEuropeanStandardsCENELECEN50160:2023“Voltagecharacteristicsofelectricitysuppliedbypublicdistributionsystems”,2023CLC/TR50422ApplicationGuidetotheEuropeanStandardEN50160on“VoltageCharacteristicsofElectricitySuppliedbyPublicDistributionSystems”,2023UNIPEDEReport“ApplicationGuidetotheEuropeanStandardEN50160”,1995UNIPEDEReport“MeasurementGuideforVoltageCharacteristics”,1995EURELEC“PowerQualityinEuropeanElectricitySupplyNetworks”-2ndedition,2023BackgroundVoltagesagsDeviationsOutlooksConclusionVoltagedeviationassessmentAEuropeanStandards--AssessmentIndex?duringeachperiodofoneweek,95%ofthe10minmeanr.m.s.valuesofthesupplyvoltageshallbewithintherangeof±10%ofnominalvoltageforLVandofdeclaredsupplyvoltageforMV.?all10minmeanr.m.s.valuesofthesupplyvoltageshallbewithintherangeof+10%/-15%(LV).

BackgroundVoltagesagsDeviationsOutlooksConclusionVoltagedeviationassessmentGB/T12325-2023thebasicmeasurementtimeintervalforsupplyvoltagedeviationisa10-cycle,andeach10-cyclemeasurementshouldbeclosetothenextintervalwithoutoverlapping;thearithmeticmeancalculationisusedoverfouroptionalaggregationintervals:3s,1min,10minand2hinaccordancewithlocalconditionsanddemands.GB/T12325alsocomplementsthetermofqualifiedvoltagerate(QVR).

BackgroundVoltagesagsDeviationsOutlooksConclusionVoltagedeviationassessmentTheproblemoftwo-sideassessmentwithpercentiles

howis5%time/locationstatisticalvaluespickedoutformtwo-sidedeviationstoobtainthe95%compatibilitylevel?BackgroundVoltagesagsDeviationsOutlooksConclusionVoltagedeviationassessmentIECmethodthedefinitionsofoverdeviationandunderdeviationaretwoindependentparameters.

Problem:iftheCP95valueofvoltageoverdeviationcomplieswiththelimitlevel(orcontractualagreement),inthe95%timeofvoltagepositivedeviationqualified,areallofthevoltager.m.svaluesqualifiedordoallofthevoltagevariationskeepintheguaranteerange?

BackgroundVoltagesagsDeviationsOutlooksConclusionVoltagedeviationassessmentAnengineeringmethodRespectivelypickingout5%fromthestatisticalspacesofunderdeviationoroverdeviation.

ProblemWhenthenumberofstatisticaldatainonesideofdeviationisverysmall,whichisalwaysacommonsense,oneshouldbecarefulabouttheconfidenceinterval.

BackgroundVoltagesagsDeviationsOutlooksConclusionVoltagedeviationassessmentAssessmentindexQualifiedrate,acoreindex,isusedascompatibilityindexbetweenpowersystemsandelectricend-users.Theworst-casevaluesofdeviationsandthenumberofconsecutivevaluesthatexceedhighand/orlowlimitsindicateawarningtosystemoperatorsandpowerqualityengineers.BackgroundVoltagesagsDeviationsOutlooksConclusionVoltagedeviationassessmentInteractionbetweenDER(distributedgenerators/theintegrationoflargescalenewsources)andvoltagedeviationassessment

DERimpactsthetime/spatialdistributionofvoltagemagnitude.BackgroundVoltagesagsDeviationsOutlooksConclusionVoltagedeviationassessmentInteractionTheselectionofindeximpactsthepenetrationrateofDERTodeterminehowmuchDERcanbeaccepted,asuitableperformanceindicatorandanappropriatelimitareneeded.BackgroundVoltagesagsDeviationsOutlooksConclusionOutlooksItisnecessarytoestablishastandardizedpowerqualityassessmentframework,tocarryoutpowerqualityparametersandeconomicassessments,improvinghorizontalandverticalcomparabilityofmeasuredorsimulateddata,inturnstopromotethemitigationofpowerdisturbances.Withthechangesofloadcomposition,weshouldresearchthecharacteristicsofdisturbancesandthesensitivemechanismofthedisturbedequipments,andimprovethelimitationandimmunitystandards;

BackgroundVoltagesagsDeviationsOutlooksConclusionOutlooksWiththedevelopmentofdistributedgeneratorsandtheintegrationoflargescalenewsources,itissignificanttostudytheinteractionbetweendistributionnetworkandDGonpowerqualityanditsassessmentmethods.

BackgroundVoltagesagsDeviationsOutlooksConclusionPowerfrequencyFlickerVoltagesagswellUnbalanceOutlooksFromequipmentsensitivitypointofview,anequipmentmaybedisturbedbyoneormorepowerdisturbancesatthesametime.