A GIS Application for Power Transmission Line.docx

A GIS Application for Power Transmission Line.docx

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AGISApplicationforPowerTransmissionLine

M.Murata

AGISApplicationforPowerTransmissionLineSiting

Inthelastfewdecades,theelectricpowerindustriesinJapanhavebeendevelopingpowertransmissionsystemstofollowupwiththerapidgrowthofthepowerdemand.Ontheotherhand,thesuitablesitefornewtransmissionlineshasbeengettingrestricted,becauseofdevelopmentofruralareasandthegrowingconcernoverenvironmentalissues.AGISapplicationsystemwasdevelopedtosupportplannersandengineersintheenvironmentalandengineeringanalysesfortransmissionlinesiting.ArcInfo,GRID,TINandNETWORKwereimplementedtoperformvariousanalysessuchastheselectionofsuitableareas,theoptimumpathfinding,theprofileanalyses,theengineeringdesignoftowersandwires,andthecostestimation.Thepurposeofthispaperistodescribetheoutlineofthissystemandthemethodologyofanalysesperformed.

1.Introduction

Atransmissionlineisoneofessentialinfrastructuresofthepowersupplysystem.Inthesiteevaluationprocessforthosefacilities,itisnecessarytocarefullyconsidernotonlytechnicalissues,butalsotheimpactonnaturalenvironment,theinfluenceonlocalcommunities,andvariousregulations.

However,itisgettingdifficulttofindthepreferablesiteforatransmissionline,becauseoftheincreasingcostofconstructions,theincreasingconcernonenvironmentalissuesandthegrowingconsciousnessoflandowners.Inaddition,thenumberofexperiencedplannersandengineersengagedinthesitingprocessisdecreasingwithgenerationalchanges.

Tosolvethoseproblems,acomputersystemhasbeendevelopedemployingGIStechnology.Thesystemintegrationprojectstartedin1988.ThefeasibilitystudieshadbeenmadeforthreeyearstoevaluatethemeritofGISsinthetransmissionlinesiting.Developmentofapplicationsstartedin1992andwillbecompletedin1995.

ArcInfo,TIN,GRID,NETWORKareusedtoperformvariousanalysesongeographicdatabasewhichisnecessaryforthesiteevaluation.Thispaperdescribestheoutlineofthesystem,andmentionstechnicaltopicsonmethodologies.

2.ApplicationSystem

Ingeneral,theprocessoftheplanninganddesignoftransmissionlinesconsistsofthefollowing5phases.

∙Planning:

Inthisphase,themasterguidelineofrouteconstructionsaresettledon,basedonthelongrangepowersupplyplan.Theoutlineisdeterminedforeachtransmissionlineplanned,whichincludesvoltage,thenumberoflines,startingandendingsubstations.

∙Survey:

Variousinformationaboutnaturalenvironment,geologicalfeatures,localcommunitiesandregulationsintheareaofinterestiscollectedinthisphase.Also,fieldsurveysareperformedastheoccasiondemands.Basedoncollectedinformation,severalalternativeroutesarecomparedintermsofenvironmentalimpact,technicalissuesandcostofconstruction.

∙BasicRoute:

Thepositionofeachtowerisdeterminedalongtheproposedroutes,referencingtopographicalmapsinthescaleof1:

50,000.Thisiscalledthe"basicroute".Inthisphase,interferenceofradiowavecausedbythetransmissionlineisestimated.Oncethefinalrouteplanisdetermined,theapplicationforpermissionismadetothegovernment.

∙DetailedRoute:

Thephotogrammetricsurveyingisperformedalongthebasicroute.Basedontheresults,thedetailedpositionofeachtowerisdeterminedinthescaleof1:

2,000.Andengineeringdesignprocessfollows,whichincludesthedeterminationoftowertype,towerheightandsupportingdevices,andthecostestimation.

∙RouteforImplementation:

Inthisphase,thedetailedfieldsurveyingisperformedalongthedeterminedroute.Thetowers,wiresandbasementoftowersaredesigned.

Thecomputersystemdevelopedheresupportsphase1to4,andconsistsof5subsystems.FIGURE2.1showstheoutlineofthesystem.

Thefunctionofeachsubsystemisdescribedasfollows.

（1）DataEntrySystem

Thissubsystemistoinstall,checkandeditthegeographicaldatabaseusedinallsubsystems.Thedatabaseincludesthefollowing.

∙TopographicalMapsin1:

50,000（rasterimages）

∙EnvironmentalInformation（Coverages）

∙LandInformationDatabase

GovernmentalBoundaries,Roads,Railroads,Rivers,Lakes（Coverages）

Altitude（GRID）

∙PhotogrammetricMapsin1:

2,000（rasterimages）

∙DTM（GRID）

（2）RouteZoneEvaluationSupportingSystem

Thepurposeofthissubsystemistoselectthezone,calledthe"routezone",whichisconsideredsuitableforatransmissionlineintermsofenvironmentalimpactandregulations.Theroutezoneisdeterminedinthescaleof1:

50,000.ThefunctionsofthissystemaredescribedinFIGURE2.2.

（3）BasicRouteEvaluationSupportingSystem

Thepositionofeachtowerisdeterminedinteractivelyreferencingthetopographicalmaps,thesuitabilitymapsandtheoptimumroutecomputedabove.Thesystemhasthefollowingfunctions.（FIGURE2.3）

（4）DetailedRouteEvaluationSupportingSystem

Oncethebasicrouteisdetermined,thephotogrammetricsurveyingisperformedalongtheroutetomakeplanimetricandtopographicmaps,andDTMsinthescaleof1:

2,000.Basedonthedatabase,thedetailedpositionofeachtowerisdeterminedinthescaleof1:

2,000.Furthermore,thesystemhasvariousfunctionstoperformtheengineeringanalyses.FIGURE2.4showsthefunctionsofthissubsystem.

（5）WaveInterferenceEvaluationSupportingSystem

Atransmissionlinemaycausetheinterferenceintelevisionandmicrowavecommunication.Thepurposeofthissubsystemistopredictthewaveinterferencecausedbythedeterminedtransmissionline.ThesystemhasfunctionsasshowninFIGURE2.5.

3.SystemComponents

ThehardwarerequirementofthesystemisdescribedinFIGURE3.1.

ArcInfo,TIN,GRIDandNETWORKareimplementedinthissystem.Inaddition,aspreadsheetpackageisemployedtoperformthecostestimation.Forengineeringcomputations,originalprogramsarecodedusingClanguage.

4Methodologies

（1）SuitabilityMapandOptimumRoute

Theexistingprocessofthesiteevaluationwasreviewedforthisproject.Astheresult,theenvironmentalinformationwasclassifiedintothreecategories,natural,socialandtechnicalenvironment.Eachofthosecategoriescontainssuchlayersasfollows.

∙NaturalEnvironment

Habitatsofendangeredspecies,Nationalparks,etc

∙SocialEnvironment

Viewpoints,Scenicareas

Culturalassets,Temples,Shrines

Agriculturalpromotionarea,Forestarea,Cities

Districtforurbanplanning,Airports,etc.

∙TechnicalEnvironment

Faults,Dangerousdistrictforcollapse

Snowfall,Thunderstorm,Saltybreeze,Windpressure,etc.

Anindexisintroducedtorepresenttherelativedifficultyoftherouteconstruction,whichhadbeendeterminedbyexperiencedengineersbefore.Theindexisdefinedasdescribedbelow.

∙Index=NCP（NegativeControlPoint）

Theroutemustnotpassthrough.

∙Index=5

Routeconstructionisstrictlyregulated,orhasagreatimpact.

∙Index=3

Routeconstructionmaybepermitted,orhasamoderateinfluence.

∙Index=1

Routeconstructionhasaslightinfluence.

∙Index=0

Noproblemforrouteconstruction.

Theindexnumberisassignedtoeachpolygonfeatureoftheenvironmentaldatabase,accordingtothedifficultyofrouteconstruction.Forpointorlinefeatures,asortofbufferprocedureisperformedusingGRIDfunction,andtheindexnumberisassignedaccordingtothedistancefromthecenter.

Thesuitabilitymapiscreatedbyoverlayingandsummingupallindexedlayers.ThisprocedurealsoutilizesGRIDfunctions,andisshowninFIGURE4.1.

Theresultedsuitabilitymapisconsideredtorepresentasortofimpedanceforrouteconstruction.UsingGRIDCOSTDISTANCEfunctions,theoptimumrouteiscomputedbasedonthesuitabilitymapasshowninFIGURE4.2.

（2）DetermineTowerHeight

Inthedetailedroute,heightofeachtowerisdeterminedtominimizethecostofconstructionofthewholeroute.ItisaccomplishedasshowninFIGURE4.3.

First,thepossiblecombinationoftowerheightiscomputedforeachspan.Therequiredclearanceofwireshouldbeensuredoverthegroundandstructures.

Then,thecombinationsoftowerheightarejoinedalongthewholeroute.Theresultisconstructedasanetworkmodelwithaturntable.Thecostofeachturniscomputed,whichdependsonthetowerheightandthetowertype.

Finally,theoptimumpathisderivedusingNETWORKPATHcommand,basedonthecostateachturn.Theresultedpathcorrespondstothemostcost-effectivetowerheightcombination.

（3）ProfilealongtheDetailedRoute

Oncethedetailedrouteisdetermined,theprofilealongtherouteisplottedasoneofthefinalresults.Thisplotincludestheprofilealongtheroute,thestructuresunderwires,therequiredclearance,thedipofwires,andthetowers.FIGURE4.4showsanexampleoftheprofileplot.ThosefeaturesareplottedusingGRAPHcommandsinARCPLOT.Thecurvesofstructures,clearanceandwirediparecomputedbyoriginalprogramscodedwithClanguage.

（4）EstimatetheConstructionCost

Thecostestimationisaccomplishedusingaspreadsheetpackage.Thespecificationsoftowersandwires,whicharestoredinINFOfiles,areconvertedtotextfilestobereadbythespreadsheet,asshowninFIGURE4.5.Useofexistingpackagesmakesiteasytocreatealedgeroftherouteortoestimatetheconstructioncost.

5.Conclusion

AGIS-basedapplicationhasbeendevelopedfortransmissionlinesiting.Thissystemsupportsfromtheplanningphasetotheengineeringdesignphaseandprovidestotalsolutionforthesitingprocess.

ArcInfoisemployedasapowerfultoolboxinthissystemtoperform