电力英文翻译.docx

电力英文翻译.docx

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电力英文翻译

PowerTechnologyandEngineeringVol.38,No.5,2004

ENERGYSYSTEMSANDELECTRICALNETWORKS

TECHNICALSTATEOFBASICEQUIPMENT

OFSUBSTATIONSANDOVERHEADTRANSMISSIONLINES

ANDMEASURESFORRAISINGTHEIRRELIABILITY

D.S.Savvaitov1andL.V.Timashova1

TranslatedfromÉlektricheskieStantsii,No.8,August2004

Abriefdescriptionofthestateofbasicequipmentemployedin110–750-kVpowernetworksispresented.Problemsarisinginoperationofthisequipmentareoutlinedandrecommendationsonimprovingitsreliabilityaremade.Transformerequipment,high-voltagecircuitbreakers,disconnectors,measuringtransformers,nonlinearovervoltagesuppressors,andtransmissionlinesareconsidered.

Keywords:

transformerequipment,high-voltagecircuitbreakers,disconnectors,measuringtransformers,overvoltagesuppressors,transmissionlines,servicelife.

Theexisting110–750-kVpowernetworkshavebeencreatedintheSovietUnionandarenowexperiencingthefollowingproblems:

—alargevolumeoftime-wornelectricequipmentatsubstations;

—poorcontrollabilityofthenetworkandinadequatevolumeofdevicesforvoltagecontrol;

—lowdesignreliabilityoftheactivetransmissionlines;

—outdateddesignofoverheadlines;

—useofsomeoutdatedtechnologiesandkindsofnetworkequipmentandcontrolsystems;

—lowlevelofautomationofnetworkobjectsandabsenceoffullyautomatedsubstations;

—inadequateperformancespecificationandmaintenanceofnetworkfacilities;

—highoperatingcosts.

Agreatpartoftheinstalledequipmenthasexhaustedstandardizedminimumservicelife.Itshouldbenotedthatdifferentkindsofequipmenthavedifferentload-lives.Ontheaverage,thesubstationequipmenthasbeenwornoutbyabout40%.RequirementsonreliabilityofthebasefacilitiesarestandardizedonlyinGOST687–78foraccircuitbreakersratedforover1000V.TheGOST687–78StateStandardalsoincludesrequirementsonthemechanicallifeevaluatedintermsofparameterNspecifiedforeverykindofcircuitbreaker.ForoverheadtransmissionlinesNisusuallyequalto1000on-offcycles.However,intheactualpracticeoverheadcircuitbreakersratedfor330–500kVfailafter240–380cycles.Wecanseethatthereliabilityofthebasepowerequipmentcanbeevaluatedonlywiththehelpofoperationaldata.Russiantransmissionlinesarechieflyequippedwithaircircuitbreakers.SF6circuitbreakersconstituteonly4%ofthetotalnumberofemployedbreakers.Theefficiencyofoperationofthesefourpercentcannotbeanalyzedatpresentduetotheabsenceofenoughdataintheirfailures.Thereliabilityofnonlinearovervoltagesuppressors（OVS）fabricatedbyvariousdomesticproducersisdeclaredinperformancespecifications,wheretheirservicelifeislimitedto25（or30）yearswithaprobabilityof0.98.Thismeansthat0.8（or0.67）outof1000OVScanfaileveryyear.Thesedeclareddatahavenotbeenconfirmedyetbyoperationalexperience.

Transformerequipment.

Transformers,autotransformers（AT）,andshuntingreactorsarereliablefacilitiesatsubstations.TherelativelyhighlevelofqualityoflargetransformershasbeenensuredintheUSSRbystrictspecializationofproducers.AlllargetransformershavebeenproducedbytheZaporozh’yeTransformerPlant（ZTZ）.TransformersfortheRussianpowerindustryareproducedbytheMoscowElectricPlant（MÉZ）.OperationalexperienceshowsthatpowertransformersproducedintheUSSRandintheRussianFederationhavereliabilitycomparabletothelevelofforeignproducers.However,themassandsizeparametersspecifiedbyGOST12965–85andGOST17544–85（USSR）andthelosses,especiallytheno-loadones,arelowerthanintheworldpractice.Atthepresenttime,thefleetofpowertransformersratedto110–750kVamountstoabout30,000pieceswithatotalpowerof570GV⎽Aincludingabout25,000piecesratedto120MV⎽A.

About30%ofthetransformerequipmenthaveservedforover25years,andin2005abouthalfofthetransformerswillserveformorethat25years.Withoutallowanceforthedamageofterminals,harddamageoftransformersproducedpriorto1970amountsto1%;fortransformersproducedlateritamountstoabout0.2%.Ananalysismadeinthelastfiveyearsshowsthatthespecificannualdamageabilityoftransformersis0.45%.Thiskindofdamageisforthemostpartsevereandisaccompaniedbyexplosionandfireduetosparkoverthroughyellowscurfontheinternalsurfaceofthebottomcoverofbushings.About23.5%offailuresoccurwithloadtapchangedevices（LTC）.IntheworldpracticeautotransformersalsofailfrequentlyduetothedamageofbushingsandLTC.5.36%failuresoccurduetoinappropriatestabilityofwindingsduringfaults,whichisthemostfrequentfor330-and500-kVautotransformers.Everyyearone-twofailuresoccurduetodefectsofmajorinsulation（includingburrsonwindingwires）.

Modernautotransformershaveanefficiencyexceeding99.5%（in500-and750-kVATtheefficiencyexceeds99.7%）andverylowdamageability.Thefollowingmeasuresaretakeninordertoraisethereliabilityoftransformerequipment:

—useofmorereliablebushings,bushingswithsolidinsulationproducedbytheKhotkovoPlantincooperationwiththeABBCompany,bushingsproducedbythe“Izolyator”Plant,andimportedMicafilbushings,nowusedseldombecauseofthehighcost;—useofmorereliableLTC.TraditionalsupplierofLTCistheMaschinenfabrikReinhausenCompany（Germany）.LessreliablebutcheaperdevicesareproducedbytheZaporozh’yeTransformerPlant;—useofdevicesformeasuringtheoiltemperaturefordeterminingtheheatloadontheATwithautomaticcontrolofcoolingdevicesinsteadofthenowusedpressure-filledthermometersthatgiveanerrorexceeding10°C;—useofforeignpracticeofmeasuringthetemperatureofwindings.Thismakesitpossibletocontroloverloadsifnecessaryandalsoindirectlycontrolthethermalwearoftheinsulation（ZTZandMÉZequipdomesticautotransformersandimportedtransformerswithsuchdevices）.

High-voltage110–750-kVcircuitbreakers.

Thenational（all-Russian）powernetworkemploysover30,000circuitbreakersratedforfrom110to750kVofwhich80.5%are110-kVbreakers,15.2%are220-kVbreakers,1.2%are330-kVbreakers,3%are500-kVbreakers,and0.1%are750-kVbreakers.Over50%oftheinstalledcircuitbreakersaretank-typeoilswitchesratedforthevoltageof110and220kV（58%areratedfor110kVand45%areratedfor220kV）.

Fromthe1930stothe1980stank-typeoilswitches（MKPandU）havebeenproducedbytheUralélektroapparatPlantandthenbytheUralélektrotyazhmashProductionAssociation.Live-tankcircuitbreakersfor110and220kVconstitute24.3%ofthetotalnumberofinstalledbreakers（27%110-Kvand17%220-kV）.TheseareVMT-110andVMT-220circuitbreakersproducedbyUralélektrotyazhmash（UÉTM）,MMO-110Bulgariancircuitbreakers,andasmallnumbercircuitbreakersimportedfromASEAandotherforeigncompanies.VMT-110andVMT-220breakersarebeingproduceduntilnow.In2000theywereshippedinanamountof285pieces,in2001theywereshippedinanamountof320pieces.TherespectivenumbersofVMT-220breakersare15and30pieces.Theamountofaircircuitbreakersisequalto18.6%ofthetotalnumberofinstalledbreakers（12%110-kV,35%220-kV,and97%330-and500-kV）.AirbreakersoftheVVN,VV,VVB,VVD,andVNVserieshavebeenproducedbytheÉlektroapparatandUralélektrotyazhmashPlants.

Until1996RussianpowersystemshadsingleSF6circuitbreakersinpilotoperation.In1997itwasdecidedtoequipnewlyerectedandreconditioned330-and750-kVsubstationsoftheRAO“EÉSRossii”Co.withSF6circuitbreakers.Thenumberofsuchbreakersincreasedprogressivelyandnowamountsto4%.SF6column-typeandtank-typecircuitbreakersaresuppliedbyUÉTM（primarily110-kVbreakerswithbreakingcurrentofupto40kA）,bythePowerMechanicalPlant（110-and220-kVtank-typebreakers）,andbyforeignproducers（ABB,Alstom,Siemens）.Aconsiderablepartoftheoilandaircircuitbreakersoperatingintheunitednational（all-Russian）electricnetworkareratedfor110and220kVandhaveexhaustedthespecifiedservicelife.Thisis35%ofthetotalnumberofbreakersinoperation.NinetypercentoftheMKP-110andVVN-110breakers,40%oftheU-110breakers,and50%oftheVVN-220breakershaveexhaustedtheirspecifiedservicelife.Thedamageabilityofcircuitbreakersisdeterminedintermsofthefailureflowcalculatedastheratioofthetotalnumberofallkindsoffailuretothetotalservicelifeofthebreakerscountedinbreaker-years.Fordomestichigh-voltagecircuitbreakersoftheVVseriesratedfor110–220kVthefailureflowparameteris0.07–0.08peryear;forthe500–750-kVswitchesitis0.13–0.15peryear.AccordingtothedataofCIGREthemeanfailureflowfor110-kVandhigher-voltagebreakersis0.01peryear.

Theworstreliabilityisreportedforthefollowingkindsofcircuitbreakers:

0.100peryearforMMO-110（Bulgaria）,0.111peryearforVVB-110,0.134peryearforVVN-220,0.129peryearforVVN-330,0.242peryearforVVBK-500,and0.065peryearforVV（M）-500.Theseswitchesdonotmeettherequirementsofmodernstandards,includingtheparametersofreliability,switchingandmechanicallives,repairvolume,mass,andsize.Domesticcircuitbreakersareknowntobedamagedforthefollowingreasons:

—designdrawbacks;

—defectsduetolowqualityofmaterials;

—productiondefects;

—performanceandmaintenancefailures;

—presenceofshuntingreactorsandcapacitorbanksincircuitsforwhichthebreakersareunsuitable;

—operationunderconditionsofshort-circuitcurrents