电力系统基础知识Basic knowledge of power systemWord文档格式.docx
《电力系统基础知识Basic knowledge of power systemWord文档格式.docx》由会员分享,可在线阅读,更多相关《电力系统基础知识Basic knowledge of power systemWord文档格式.docx(6页珍藏版)》请在冰豆网上搜索。
Powersystem:
powergenerationequipmentonthebasisofthepowergrid.
Basedonthepowersystem,thepowerplantparts(suchasthermalpowerplantboiler,steamturbineandhydropowerplantreservoir,hydraulicturbineandnuclearpowerplantreactoretc.)areincludedinthesystem.
Three.Characteristicsofpowersystemoperation
First,thetotalamountofeconomyisbig.Atpresent,China'
spowerindustryassetsizehasmorethan2trillion,accountedforatotalof1/4ofthestate-ownedassets,electricityproductiondirectlyaffectsthehealthydevelopmentofthenationaleconomy.
Thetwoisatthesametime,alargenumberofelectricitycannotbestored,unitycomposedofallsectorscannotbeseparated,thetransitionprocessisveryrapid,instantproductionpowermustbeequaltothemomentforeveryaspectofpower,sothepowerproductionofthepowergeneration,transmissionanddistributionareveryimportanttotheuser.
Thethreeisconcentrated,electricityproductionishighlycentralizedandunified,nomatterhowmanypowerplants,powercompanies,powergridmustbeunified,unifiedmanagement,unifiedmanagement;
safetyproduction,organizationanddiscipline,occupationmoralityhasstrictrequirements.
Thefourisapplicability,theserviceobjectofpowerindustryisall-round,involvingallthepeopleinthewholesociety,powerquality,electricitypricelevelandtheinterestsofthevastnumberofpowerusersarecloselyrelated.
Fiveisadvance,thedevelopmentofthenationaleconomy,electricitymustfirst.
Four.Ratedvoltageofpowersystem
Thereisalevelofpowergridvoltage,ratedvoltageisreasonableaccordingtotheneedsofnationaleconomicdevelopment,technologyeconomyandelectricalequipmentmanufacturinglevel,throughthecomprehensiveanalysisanddemonstration,enactedbythenationalunity.
Five、neutraloperationmodeofpowersystem
Inthepowersystem,neutralgroundingorneutralsmallimpedance(lowresistance)groundingsystemiscalledgroundingsystem,neutralorneutralPetersencoilgroundedsystemiscalledsmallcurrentgroundingsystem.Theoperationmodeofneutralpointmainlydependsontheinsulationrequirementofelectricalequipmentandthereliabilityofpowersupplyinsinglephasegrounding.
Comparisonofadvantagesanddisadvantagesofdifferentoperationmodes
Neutralpointdirectgroundingmode:
whenarelativeinsulationfailureoccurs,thesingle-phaseshort-circuitisformed,thepowersupplyisinterrupted,andthereliabilityisreduced.However,underthismode,thenonfaultrelativevoltageisconstant,andtheinsulationleveloftheelectricalequipmentcanbeconsideredintermsofphasevoltage.The220V/380Vand110KVinourcountryuseneutralpointdirectgroundingtohighersystem,andoperateinlargecurrentgroundingmode.
Ungroundedorgroundedbyarcsuppressioncoil:
whensingle-phasegroundingfaultoccurs,thelinevoltageisconstant,andthenonfaultphasevoltagetophasevoltageoftheoriginaltick3times,uninterruptedpowersupply,highreliability.The10KVand35KVsystemsinourcountryuseneutralungroundedorarcsuppressioncoilstooperateinsmallcurrentneutralgroundingmode.
Six、powersupplyquality
Voltage,frequency,andreliabilityaretheindicatorsthatdeterminethequalityoftheuser'
spowersupply.
1.voltage
Theidealsupplyvoltageshouldbeathree-phasesymmetricalsinusoidalvoltagewhoseamplitudeisconstant.Duetothepresenceofimpedance,powersupplysystemwiththechangeofpowerloadandelectricityloadpropertiesandotherfactors,theactualsupplyvoltageregardlessoftheamplitude,waveformandphasesymmetryandidealvoltageexistsbetweenthedeviation.
(1)voltagedeviation:
voltagedeviationisthedifferencebetweentheactualvoltageandtheratedvoltageofthepowergrid.Theactualvoltageistoohighorlow,whichhasanimpactonthegoodoperationofthepowerequipment.
Thenationalstandardprovidesthattheallowablevalueofvoltagedeviationis:
Aand35thousandvoltsandabovevoltagesupply,thesumoftheabsolutevalueofvoltagepositiveandnegativedeviationshallnotexceed10%oftheratedvoltage;
B,10thousandvoltsandbelowthree-phasepowersupply,voltagedeviationisratedvoltageof+7%.Inthe
C,220voltssingle-phasepowersupply,voltagedeviationisratedvoltageof+7%,-10%.
Theallowablevalueofvoltagefluctuationisstipulatedbythenationalstandard:
10KVandbeloware2.5%
35to110KVis2%
220KVandaboveis1.6%
(3)harmonicgeneration:
thegenerationofhigherharmonicsisnonlinearelectricalequipment,whichisputintooperationinthepowergrid,whichmakesthevoltageandcurrentwaveformsofthenetworkdistortedindifferentdegreesanddeviatedfromthesinewave.
Inadditiontothebackgroundharmonicsofthepowersystem,
Itismainlycausedbynonlinearpowerequipment,suchaslargepowerconverterandelectricarcfurnace.Theexistenceofhigherharmonicsleadstotheincreaseofenergyconsumption,theagingofelectricalequipmentinsulation,andinterferencewiththenormaloperationofautomationdevicesandcommunicationfacilities.
(4)three-phaseasymmetry:
three-phasevoltageasymmetryreferstotheamplitudeandphaserelationofthethreephasevoltages.Thethree-phaseasymmetryismainlycausedbytheasymmetryofthesystemoperatingparametersandtheunbalancedthree-phaseload.Theasymmetricoperationofpowersupplysystemisharmfultothepowersupplyequipmentandpowersupplyanddistributionsystem.Theasymmetricaloperationofthelow-voltagesystemwillleadtodeviationoftheneutralpoint,thusendangeringthesafetyofthepeopleandequipment.
Underthenormalmodeofoperationofthecommonconnectionpointofthepowersystem,theallowablevalueoftheimbalancebytheStateshallbe2%,notexceeding4%forashortperiodoftime,andnomorethan1.3%oftheindividualusers
2.permissibledeviationofsupplyfrequency
Thesinusoidalalternatingcurrentgeneratedbyageneratorinagridiscalledfrequencypersecond,andthestandardfrequency50HZ.isspecifiedinChina
China'
snationalstandardstipulatesthattheallowablevalueofthenormalfrequencydeviationofthepowersystemis+0.1Hz,andinactualimplementation,whenthesystemcapacityislessthan300Mv,thedeviationvaluecanberelaxedto+0.5Hz.
3.reliabilityofpowersupply
Thereliabilityofpowersupplyreferstothetimeandfrequencyofthepowerfailureofapowersupplyenterpriseduringacertainstatisticalperiod,whichdirectlyreflectsthecontinuouspowersupplycapabilityofthepowersupplyenterprise.
Powersupplyreliabilityratereflectsthenationaleconomycanmeetthepowerneedsoftheelectricpowerindustry,hasbecomeoneofthestandardmeasureofacountry'
slevelofeconomicdevelopment;
thepowersupplyreliabilitycanbemeasuredwiththefollowingyearaseriesofindicators:
powersupplyreliabilityrate,theaverageuseroutagetime,useraveragepowerfrequency,theaverageuserfaultoutagetimes.
Thereliabilityrateofurbanpowersupplyprescribedbythestateis99.96/100.Thatis,theaverageannualoutagetimeisnotmorethan3.5hours;
Electricalload:
thesumoftheactualpowerusedbyauser'
selectricalequipmentatagivenpoint.
Therearemanymethodstoclassifypowerload,andthemostsignificantistoclassifytheloadclassificationaccordingtothetimethattheloadoccurredinthepowersystemandthedegreeoflosscausedbythesuddeninterruptionofpowersupply.
Loadclassificationbytime
1,peakload:
referstothepowergridortheuserinaday'
stimethemaximumloadvalue.Theaveragedailyloadis24hoursaday.Theaverageloadisthemaximumload,usuallywith1monthpeakloadandonemonthpeakload.
2,minimumload:
referstothepowergridortheuserin24hoursaday,theminimumelectricityconsumptionload.Usually,thereare1monthsdailyminimumload,onemonthminimumloadandsoon.
3.Averageload:
theaveragehourlypowerconsumptionofagridorauseratacertainperiodoftime.
Classificationofdegreeofdamagecausedbyinterruptionofpowersupply
1,aload:
asuddenpoweroutagewillcausecasualtiesorcauseseriouspollutiontothesurroundingenvironment,causinghugeeconomiclosses,suchaslargeimportantequipmentdamage,importantproductsorrawmaterialsfortheproductionofalargenumberofscrapproducts,continuousproductionprocessisdisrupted,ittakesalongtimetoresumeproduction;
andasuddenpoweroutagewillcauseseriouspublicdisorderorinpoliticshavesignificantadverseeffects,suchastheelectricityloadimportanttransportationandcommunicationhub,internationalsocialplacesetc..
2,twoload:
asuddenpoweroutageintheeconomywillcausemorelosses,suchastheproductionofmajorequipmentdamage,largenumberofscrappedproductsorproduction,continuousproductionprocesstakesalongtimetorecover;
andasuddenpowerfailurecancausesocialdisorderorinpoliticscausedgreatinfluence,suchastransportationandcommunicationshub,thecity'
smainwatersourceel