分布式网络中基于时间变化负载的降低损耗与提高可靠性的分布式发电遗传算法的优化配置(IJISA-V5-

I.J.IntelligentSystemsandApplications,2013,04,55-63PublishedOnlineMarch2013inMECS()DOI:10.5815/ijisa.2013.04.05Copyright©2013MECSI.J.IntelligentSystemsandApplications,2013,04,55-63GABasedOptimalPlacementofDGsforLossReductionandReliabilityImprovementinDistributionNetworkswithTimeVaryingLoadsZahraBoor,SeyyedMehdiHosseiniDept.ofComputerandElectricalEngineering,BabolNoshirvaniUniversityofTechnology,Babol,[e-mail],[e-mail]—Thedistributedgeneration(DG)locationshavesignificantimpactsonnetworkreliabilityandloss.ThispaperpresentsamethodforoptimalDGallocationandsizingindistributionsystemsinordertoreducenetworklossandimprovesystemreliabilityatthelowestcost.Forthispurpose,amulti-objectivecostfunctionconsideringactivepowerloss,reliabilityindexandDGcostisusedtofindtheoptimalsizeandlocationofDGunits.Also,aloaddurationcurveincludingfourloadlevelswithdifferentweightingfactorisconsidered.Moreover,theoptimizationtechniquethatisbasedonGeneticAlgorithm(GA)isimplemented.Inthispaper,ECOSTindexisconsideredforreliabilityevaluationinthecostfunctionandalso,theeffectssystemreconfiguration,isalsoconsideredforreliabilityassessment.Toevaluatetheproposedalgorithm,theIEEE33-busand69-bustestsystemsareemployedandtheresultsobtainedrevealtheeffectivenessofproposedmethod.IndexTerms—DistributedGeneration,GeneticAlgorithm,Reliability,LossReduction,MultilevelLoadsI.IntroductionNowadays,theimplementationofdistributedgeneration(DG)hasbeenincreasedindistributionsystems.DGsaresmallgeneratingunitsthatareusuallyembeddedintheelectricpowersystemneartheloadcenters.ManystudieshavebeendonetoevaluatetheimpactofDGsontheoperationofdistributionnetworks.InstallingDGcanbemuchbeneficialfortheconsumersandutilitiesindistributionsystems,especiallywhenthecentralgenerationisnotapplicableorwhenthereareshortagesinthetransmissionsystem.SoinstallingDGmayhavesignificantinfluenceonpowerflow,lossandreliabilityindicesindistributionsystems,whichcouldbepositiveornegative.Itwouldbepositiveiftheyareproperlycoordinatedwiththerestofthenetwork.Moreover,DGunitscanincreaseshortcircuitcurrent,causeinstabilityoffrequencyandvoltageanddecreasesensitivitytofaults.Thepowerdemandgrowthisacriticalconcernforthepowerutilitiesastheymustalwayssupplythecustomerswiththeleastinterruptionsandcost.IntegrationofDGunitstodistributionnetworkscanbeabettersolutionthatdefersinvestmentsofupgradingexistentpowersystems.Ifthesystemtopologyisassumedtobeconstantduringtheplanningperiod,theappearanceofnewloadsorthepeakloaddemandgrowthtothenetworkcouldshowusthelackofamoreupgradednetwork.Inthiscase,DGcanbeavaluablechoicefortheplanningengineerstoreduceinvestmentsforupgradingthedistributionsystembecauseitislocatedneartheloadanddoesn‟tneedasmuchtransmissionanddistributioninfrastructurestoservedloads.Inadditiontothisadvantage,themainadvantagesofDGcanbeexpressedasfollows:improvingthesystemreliability,improvingvoltageprofile,powerlossreduction,lesspollutingemissions(incomparisontotraditionalmachines)[1],feasibilitytouseCHP(CombineHeatandPower)generation.Inpowersystems,lossandreliabilityaretwosignificantpointsamongseveralfactorsthatcanbeconsidered,especiallyindistributionsystems.ActuallytwoofthemostimportantDGprofitsarelossreductionandreliabilityimprovement[2].Although,usingDGscanlowerthelossandhigherthereliabilityetc,indistributionnetwork,itcanapplyahighcapitalcosttothesystem,too.ItisobviousthatthesizeofDGshasasignificantroleinbothreliabilityimprovementandlossreduction.Thus,thesizeofDGsshouldbeoptimizedwhentheyareallocatedinthesystem.Theplanner‟smainaimisfindingthebestsolutionthatallowsminimizingtheoverallcostwithinthetechnicalconstraints,becausecostisanimportantfactorinpowerplanning.InsomecasesDGcansignificantlyreducecost(andimprovereliability)morethanthemainnetworkforcustomerswhentheybeplacedintherightpositionofthedistributionsystem.TheproblemofDGsizingandallocationhasgreatimportance.TheinstallationofDGsattheplacesthatisnon-optimal,cancauseanincreaseinsystemlosses,resultinganincreaseincostsand,therefore,havinganegativeimpact.Although,minimizingthepowerlossandimprovingthereliabilityatthesametimewillhaveverybetterresultsthanoptimizingonebyone,onlya56GABasedOptimalPlacementofDGsforLossReductionandReliabilityImprovementinDistributionNetworkswithTimeVaryingLoadsCopyright©2013MECSI.J.IntelligentSystemsandApplications,2013,04,55-63fewpapershaveconsideredthecombinationoftheseelements[3-6].LossminimizationisstudiedinalmostallpapersstudyingDGs[7-11]andsomepapershavestudiedthereliabilityimprovementofDGs[12].AlsotherearemanystudiesfocusingontheoptimalsizeandlocationofDGsindistributionsystems.In[6],theauthorsconsideredthereliabilityofthesystemandlinelossasaconstraintintheDGplanningproblemforreducinglinelossandimprovingreliabilityofthesystemandvoltageprofilebyusinggeneticalgorithm(GA)asanoptimizationtechnique.In[4]GAisusedtofindtheoptimallocation,type,andsizeofDGsindistributionsystemsinordertomaximizethereliability.In[13]combinationofgeneticalgorithm(GA)andtabusearchi