Five minute guide to microgrids

Fiveminuteguide:Microgrids(µG) Fiveminuteguide Microgrids(µG) WhatisaMicrogrid? Amicrogridisalocalenergysystemwhichincorporatesthreekeycomponents;Generation,StorageandDemandallwithinaboundedandcontrollednetwork.Itmayormaynotbeconnectedtothegrid. Amicrogrid(µG)isadistributedlevelenergysystemwhichincludesallthenecessarycomponentstooperateinisolationofthegrid. Itisamicrocosmofthebroaderenergynetwork,butatadistributedlevel. Whenoperatingindependentlyofthegridin‘island’mode,amicrogridisaself-sustainingindependentenergysystem.ItcanalsobeconnectedtothegridthroughaPointofCommonCoupling(PCC),allowingittoimportorexportelectricityasprevailingcommercialortechnicalconditionsdictate. Microgridgenerationmaybefromarangeofvariabledistributedenergyresources(DER’s),includingrenewablesandfossilfuelledgenerators.Storagemayincludebatteryarrays,electricvehicles,liquidairamongothers.Demandismodulatedthroughthemicrogridcontrolsystemsincorporatingdemandresponse(DR)sothatit canbematchedtoavailablesupplyinthemostsafe,effectiveandcontrolledway. Microgridsarepredominantlyelectricallybased,buttheycanalsoincorporateathermalenergycomponent. TheyoperateasAC,DC,highfrequencyACoracombinationofallthree. Grid PointofCommonCouplingPCC Generation Storage ACDCHfAC Demand µGcontrolsystem Secure,SustainableandAffordable Amicrogridisawaytosimultaneouslyaddressenergysecurity,affordabilityandsustainabilitythroughdispersed,locallycontrolled,independentenergysystemstailoredpreciselytoend-userrequirements. Differentend-usershavearangeofrequirementsfromtheirenergysupplysystems.Whilefinancialinstitutionsandhightechnologyindustriessuchasmicrochipmanufacturers ordatacentresrequireabsolutesupplyreliability,othersmaybemorefocussedonthesustainabilityandcarbonfootprintoftheir supply.Inothercircumstances,affordabilitymaybetheprimarydriverorsimplytheopportunitytohaveanypoweratall,particularlyinareaswheregriddevelopmentislimitedorsuppliesrelyonexpensiveimportedfossilfuels. SecureandReliable Byvirtueofbeingaself-containedsystem,amicrogridisresilienttoenergysupplydisruptions.Thetimeframeofthisresiliencevariesfromagridindependentsystemwhichcanoperateaslongasfuelorrenewableenergyisavailabletoasystemwhichoperatesforshortperiodstoprotect Themicrogridcanfocusoncriticaldemandsonly,leavingsheddableloadsoff-lineuntilfullsystemavailabilityofadequategridsupplyisresumed. Aswellasgainingtheresiliencebenefitsofbeingself-contained,amicrogridcanalsoreverttoagridsuppliedarrangementwherebeneficial. SustainableandLowCarbon Increasingpenetrationofrenewableenergyintothemixbringsmanybenefitsintermsofsustainablelowcarbonsourceswhilealso introducingintermittencyandsupply/demandchallenges.Amicrogridiswellsuitedtomatchingupintermittentrenewableswitharangeofdemandrequirements.Thesystemcanmaintaincriticalloadsfromrenewablesupplysources,whileadjustingothersandsheddingnon-criticaldemandsuntilsupplychallengeshavepassed. ThecombinationoffeedingDCloadsfromDCsourcessuchasphotovoltaicsreducesconversion AffordableandProfitable Amicrogridallowstheusertoselectthemostcosteffectivesystembalancebyselectingtheoptimalcombinationofindigenoussupplyanduse,relyingongridorexpensivestandbysupplyonlywhencosteffective.Wherethereisanimbalance,excesssupplycanbestoredordispatchedtothegrid. Wherethereisanenergyshortfallorsupplycostsarehigh,thenenergymaybedrawnfromstorage,andnon-criticalloadscanbetemporarilycurtaileduntilthesupplyprofilerecovers.Minimallossesfromconversionofdistributionmeanthatenergyisusedcost-effectively. µG Secure&Reliable againsttheundesirableeffectsofgriddisruption. losses,asdoesthelocaluseofenergyandreduceddistributionnetworklosses. Affordable&Profitable Sustainable &LowCarbon BalancingSupplyandDemand Microgridshavetheabilitytomaintainabalancebetweenavailablesupplyanddesirableloaddemandthroughcarefulmarriageofsupplyanddemandcombinedwithintelligentcontrolofanyimbalance. Microgridscanbeconfiguredinanumberofwaysbasedontherequiredreliability,sustainabilityandaffordabilityemphasistogetherwithconsiderationofthelocalgridcharacteristicsandavailability.Theabilityofamicrogridtomaintainasupply/demandbalanceisakeyattribute. Microgridenergysupplycomprisesanumberofcategoriesrangingfromreadilycontrolledtointermittentandnotcontrollable.Thisrangeincludesdispatchablegenerationsuchasdieselgeneratorsorfuel cellsatoneend,throughpredictableintermittentsupplysuchasPVormicro-hydroandontolesspredictableintermittentsupplyfromwindgenerationattheotherendofthescale. Microgridenergyloadhasarangeofcontrollabilitycharacteristicsrangingfromcriticalloadssuchasdatasystemsorlifesupportmachineryatoneendofthescale,toadjustableloadssuchasheating/cooling,lightingorgriddispatchattheother.Theextenttowhichtheloadscanbemodulatedaswellasthetimeperiodoverwhichtheycanbechangedarekeycharacteristics.Someloadsmayalsobetemporarilycurtailedwherenecessary. Microgridenergystorageprovidesacriticalsupplyfall-backaswellasameansto‘time-shift’owngenerationtomatchloaddemands. Eachtypeofsupply,demandandstoragecanbecategorisedonthebasisofitscontrollabili