同塔双回输电线路雷击同跳保护分析

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1、浙江大学硕士学位论文ABSTRACTWiththerapidlygrowthofconstruction—landprice，double—circuittransmissionlinesonthesametowerarewidelyusedtOincreasethetransmissioncapacityinthesamewidthofthetransmissioncorridoratpresent．Comparedwithregularsingle—circuittransmissionli

2、nes，thedouble-circuittransmissionlinesfacemoreseriouslightning-protectionproblems，inwhichsimultaneoustrip—outcausedbylightningstrokeistheworst．Howtoavoidthesimultaneoustrip—outaccidentsindouble-circuittransmissionlinesbecomesthekeyissuethatseriouslya

3、ffectsthestabilityofthepowergridandneedtobesolvedassoonaspossible．Inthispaper,electromagnetictransientprogram(EMTP)isusedtorecurtheaccidentswhichhappenedin220kVdouble—circuitlinesinpractice，andthesimultaneoustrip·-outmechanismindouble-·circuittransmi

4、ssionlinesonthesametowerisrevealed．Thestudyshowsthat：althoughthepowerfrequencyvoltageisnottheprimarycauseoflightningflashover，ithasasignificantimpactontheflashoversequenceoftheconductors；groundingresistancehasagreatimpactonthelightningwithstandlevel，

5、itissuggestedthatthegroundingresistanceofthedouble—circuittransmissionlinesonthesametowerisnotlargerthan10Qinheavylightningarea．Thispaperalsoanalysestheapplicationeffectoftheunbalancedinsulationondouble—circuittransmissionlines．Theresultsshowthatbyme

6、ansofensuringenoughdifferencebetweeninsulationlevelsforthetwocircuits．itcanmakesurethatwhendoublecircuittransmissionlinesonthesametowerislightning—strickenthephase·to—phaseflashoveronlyhappensatthecircuitwiththelowerinsulationlevel，thereforetheseriou

7、sfaultofsimultaneoustrip—outoftwocircuitscanbeavoidedatthecostoftrip—outofonecircuit．Calculationresultsshowthatwhenthedegreeofinsulationunbalancednessfordouble220kVor1l0kVcircuittransmissionlinesonthesametowerreachesto30％，orinotherword，thedifferencei

8、ninsulatorpiecesofastringbetweentwo220kVcircuitsortwo10kVcircuitsis4or3pieces浙江大学硕士学位论文respectively,theunbalancedinsulationcanrestrictthecircuit，wherephase．to．phaseflashoverhappens．Besides，theeffectofsuchameasureisreliableandsuitablefordoublecircuitt