On Overcurrent Protection: Short-circuit Current, Protection Coordination and Fuse Sizing in IBRs Dominated-distribution Feeders

Name: MURILLO COBE VARGAS

Publication date: 17/11/2023

Examining board:

Namesort descending Role
AUGUSTO CESAR RUEDA MEDINA Examinador Interno
FELIPE VIGOLVINO LOPES Examinador Externo
JOSÉ CARLOS DE MELO VIEIRA JÚNIOR Examinador Externo
LUCAS FRIZERA ENCARNACAO Examinador Interno
OURESTE ELIAS BATISTA Presidente

Pages

Summary: Therapidintegrationof inverter-baseddistributedpowergeneratorsareposingchallenges fortheprotectionoftheelectricalpowersystem,especiallyduetotheuncertaintyand change inthe level of short-circuit current (SCC)of distribution feeders.This thesis proposesthreeapproaches.ThefirstisamethodologytoestimatethevalueoftheSCC levelattheinstallationpointsofovercurrentprotectiondevicesindistributionnetworks withhighpenetrationof inverter-basedresources(IBRs), forthree-phasefaults(3LG)and single-phasegroundfaults(LG).Thesecondproposesamethodologyforadjustingthe characteristiccurveof inverse-timeovercurrentrelays.Andthethird, twomethodologies forsizingfusestoavoidsolidaritytrippingortoprotecttheconductor.Themethodologies areappliedinscenarioswithhighpenetrationof IBRsanddonotrequirecommunication links,normeasurementofparameters inreal time:minimalneedtoreplaceequipment alreadyinstalled.ConsideringtheestimationofSCC,themethodologypresentsagood assertivenesswhencomparedwithacomputational simulationinMATLAB/Simulink. Errorsaresmallerfor3LGfaults(<2.1%).ForLGfaults,theerrorsaresmallerwhenthe IBRsareinstalledinthemainfaulttrunk(<10.3%)thaninthelateralones(<-13.0%). Despitethehigherrors, it ispossibletoestimateanextremevalueofSCCtobeused intheprotectionadjustment. Inascenarioof100%penetrationof IBRs, therewasa miscoordinationbetweentheprotectiondevices: relay-relayandrelay-fuse.Coordination wasre-establishedusingtheproposedmethodologyforextremeIBRinstallationsituations. In this coordinationof the inverse time-overcurrent protection, the timedial of the overcurrentrelayswasmodified.Thismodificationaccommodatesahighpenetrationrange of IBRsand, inthecaseof100%penetration, itdelayedtheprotectionactuationbyafew tensofms.Forfuses, itwasfoundthatdependingonthelevelofpenetrationof IBRson thelateralbranchthatthefuseprotects, theremaybeanincompatibilityofthelimits usedfor its sizing.This incompatibilityhappens forhighpenetrationlevelswhenthe maximumcurrentthroughthefuseishigherthanitsnominalvalue.Methodologiestoavoid sympathetictrippingandconductorprotectionwereappliedtocalculatetheappropriate fusetoprotectthelateralbranchandthemaximumlevelofpenetrationrequired.The maximumpenetrationleveldecreasesastheIBRcaninjectagreaterSCC(e.g.,1.2pu or2.0pu).Theappliedmethodologiesre-establishedthecoordinationofthedistribution feeder,bothforthemaintrunkandforthesidebranches.Theseproposalscanbeapplied tootherfeedersandthepenetrationrangetobemet isdefinedbythenetworkmanager.

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