外文翻译-变电站与电力系统继电保护

-1-附录1：外文资料翻译A1.1SubstationandPowerSystemProtectionWiththedevelopmentofundertakingoftheelectricwirenetting,thepatternofnationalnetworkhasalreadytakenshapebasically.Scientificandtechnologicallevelraise,electricenvironmentalprotectioncanstrengthen,makescientificandtechnologicalcompetenceandadvancedinternationalstandards,Chineseofpowerindustryclosedaybyday.Electricmanagementlevelandservicelevelarebeingimprovedconstantly,strategicplanningmanagementofelectricpowerdevelopment,productionoperatemanage,electricmarketadministrationandelectricinformationmanagementlevel,high-qualityservicelevel,etc.generaltoraiseenterprise.Thepurposeofasubstationistotransformthecharacteristicsoftheelectricalenergysuppliedtosomeformsuitableforuse,asforexample,aconversionfromalternationcurrenttodirectcurrentfortheuseofcityrailwayservice,orachangefromonevoltagetoanother,oronefrequencytoanother.Theirfunctionsinclude:Tap.─TObeeconomical,transmissionoflargeramountsofpoweroverlongdistancesmustbedoneatvoltagesabove110,000volts.Substationsforsupplyingsmallamountsofpowerfromsuchhigh-voltagelinesarenotsatisfactoryfromthestandpointofoperationandarealsouneconomical.Itis,therefore,commonpracticetoinstallafewsubstationsatadvantageouspointsalongthehigh-tensionlinesandstepdownthehigh-transmissionvoltagetoalowersecondary-transmissionvoltagefromwhichnumeroussmallloadsmaybesupplied.Distribution.─Anysubstationthatisusedtotransformelectricalenergytoapotentialthatislowenoughforgeneraldistributionandutilizationisadistributingsubstation.Suchasubstationwillgenerallyreceiveitsenergyoverafewcomparativelyhigh-tensionlinesanddistributeitoveralargenumberoflow-voltagelines.Industrial.─Whenfairlylargeblocksofpowerarerequiredbyindustrialplants,itoftenbecomesnecessaryandadvisabletoinstallanindividualsubstationtosupplysuchaloaddirectlyfromthemainhigh-voltagelineorsecondarylineoflowervoltage.Itssimplestformwouldcompriseonlyswitchingequipment,therebeingnovoltagetransformation.Inmostcasesavoltagetransformationisprobablyneeded;hencetransformerequipmentisincluded.Sectionalizing.─Inverylonghigh-voltagelargecapacitylines,particularlywhenseveralcircuitsareruninparallel,itisoftennecessarytosplitthelinesintosections,inorderthatproperprotectiontothelineandservicecanbeobtained.Suchasubstationis,therefore,helpfulinsectionalizingdamagedsectionsofaline,providingcontinuityofservice.Suchasubstationwillgenerallycompriseonlyswitchingequipment.Inlonglinesitmayalsoservetosupplypower-factor-correctingequipment.Transmission-lineSupply.─Itisbecomingmoreandmorecommontoinstallthehigh-tensionequipmentofapowerplantoutdoors,theinstallationbecomingnothingmorethanastep-upsubstationreceivingitspoweratgeneratorvoltage,thensteppingupitsvoltageandfinallysendingitoutoverhigh-voltagetransmissionlines.Sucha-2-substationisnothingmorethananoutdoordistributingsubstationturnedaround,thevoltagebeingsteppedupinsteadofsteppeddown.Power-factorCorrection.─Thevoltageattheendoflonglinestendstoincreaseastheloadsuppliedisdecreased,whileontheotherhandittendstodecreaseastheloadisincreased.Owingtotheinductanceandcapacityeffects,thisvariationinvoltageisaccompaniedbyawidevariationinpowerfactorofaline,itisnecessarytousesynchronouscondensersattheendoftheline.Tosupplysuchamachinethetransmission-linevoltagemustbesteppeddown,henceapower-factor-correctingsubstationwillincludeswitchingequipment,transformers,andallequipmentnecessaryfortheoperationofsynchronouscondensers.Railway.─Substationssupplyingrailwaysmaybegenerallyclassifiedundertwoheads,namely,asalternatingcurrentandasdirectcurrent.Inthecasesofalternating-currentsubstationstheproblemisgenerallyoneofvoltagetransformationandofsupplyingsingle-phasepowertothetrains.Itis,however,possibletosupplysingle-phasetothree-phaseinsidethelocomotivebytheuseofaphaseconverter.Inthecaseofdirect-currentrailways,thesubstationsaregenerallysuppliedwhitthree-phasepowerandconvertedtodirectcurrentbymeansofrotaryconverters,motor-generatorsets,orrectifiers.DirectcurrentforLightandPower.─Therearestillafewsectionsinsomeofoutlargecities,whicharesuppliedwithdirect-currentthree-wiresystems.Suchasupplyisinvariablyobtainedfromsynchronousconverters.Therearealsocertaintypesofmotorloadsinindustrialplants,whichrequiredirectcurrent.Becausemanycitieshaveexperiencerapidgrowth,theirsubstationshaveoftenreachedthelimitsoftheircapacity.Asaresult,downtowndistributionsystemsareoftenoverworkedandmanyneedamajor,overhaul,overhaul,orexpansion.However,spaceisscarce.Downtownbusinessownersdonotwant“ugly”newsubstationmarringthearea’sappearance,butnordobusinessesandresidentsgridtheprospectofgriddisturbances.OneexampleofasystemcapableofintegratingequipmentmonitoringwithsubstationautomationistheGEHarrisintegratedSubstationControlSystem(ISCS).Thesystemcanintegratedatafrombothsubstationsystemandequipmentonlinemonitoringdevicesintoacommondatabase.Thedatacanthenbeprocessedbyanexpertsystemintoinformationonthestatusandhealthofmonitoredequipmentusingself-diagnosticprograms.ThisinformationisthensenttoaCMMSforautomaticgenerationandtrackingofma