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1、电气工程专业英语课件lecture4XX 1各位老师上午好！各位老师上午好！Lecture4Specialized Englishfor ElectricalEngineering2Lecture4Reading andTranslationDistribution Systemsand LoadsPart1Introduction ofDistribution SystemsSomeindustrial customermay besupplied atsuch voltage levels in a range of34.5kV to138kV whichbelong transmissi
2、onlevels,but mostelectric customers are supplied by feedersin thedistribution system.The primarydistribution voltageranges from4kV to34.5kV andis monlybetween11kV and15kV.Small industrialcustomers aresupplied byprimary feedersat thisvoltage levelfrom theprimary system,which alsosupplies thedistribut
3、ion transformersproviding secondaryvoltagesover single-phase three-wire circuitsfor residentialand mercialcustomers at120V/240V.Other secondarycircuits arethree-phase four-wire systems.3Lecture4As illustratedin Fig.6.1,the aggregatedload represented at atransmission substation(bus A)usually includes
4、,in additionto theconnected loaddevices,the effectsof substationstep-down transformers,subtransmission feeders,distribution feeders,distribution transformers,voltage regulators,and reactivepower pensationdevices.4Lecture41.Small industrialcustomersaresupplied byprimary feedersat thisvoltagelevelfrom
5、 theprimary system,which alsosupplies thedistribution transformersproviding secondaryvoltages oversingle-phase three-wire circuitsfor residentialand mercialcustomers at120V/240V.小型工业用户由一次系统中此电压等级的一次馈线供电。 一次系统也给经过单相三线电路为居民用电和商业用户提供小型工业用户由一次系统中此电压等级的一次馈线供电。 一次系统也给经过单相三线电路为居民用电和商业用户提供120V/240V二次电压的配电变压
6、器供电。 2.As illustratedin Fig.6.1,the aggregatedload representedat atransmission substation(bus A)usually includes,in additionto theconnected loaddevices,the effectsof substationstep-down transformers如图6.1所示，在输电变电站（母线A）所给出的集合负荷，除了所连接的负荷设备以外，通常还包括变电站降压变压器的影响）所给出的集合负荷，除了所连接的负荷设备以外，通常还包括变电站降压变压器的影响。 5Lec
7、ture4Part2Familiar Loadsand TheirClassificationRoughly,loads aredevices thoseconsume electricenergy orelectric powerconsumed bycustomers mainlyin distributionsystem.The loadsabsorb electricenergy fromthe power system andconverts itinto energyof otherforms,which maybe heatenergy toheat wateror tomelt
8、 irons,or mechanicalenergy todrive amachine,etc.They canbe dividedinto variousclasses aording to differentconditions.For instance,the threefundamental loadclasses,aordingtothe situationswhere theyare used,are industrial,mercial andresidential loads.6Lecture4The classificationby servicerequirements i
9、salso usedsometimes.From thisviewpoint,some loadsrequire simplyenough electricenergy,in otherwords,the quantityis theprimary desire.This kindof loads,especially thoseconsume energycalculated bystandard coalsmore over10thousands oftons peryear,has aname ofhigh energy consuming loads.A metallurgicalpl
10、ant withone ormore largecapacity EAFs(Electric ArcFurnace)for meltingmetal is the typicalinstance.For someother industries,high power supply qualityistheprimary desire.For example,banks andsettlement centersrequirestrictly continuouslyservice,which isof extremeimportance for them tokeep thedata inta
11、ctand consistent.As topowersupplyfor agricultural irrigation,almost nospecial requirementexists.7Lecture4The loadstatus isvery importantfor a power system.The powersystem iscalled ina largemode ofoperationunder heavyload conditions,and similarly,the termsmall modefor lightloads.Tab.6.1lists somefami
12、liar loads.8Lecture41.Roughly,loads aredevices thoseconsume electricenergy orelectric powerconsumed bycustomers mainlyin distributionsystem.粗略的讲，负荷是主要在配电网中消耗电能的设备或者由用户消耗的功率。 粗略的讲，负荷是主要在配电网中消耗电能的设备或者由用户消耗的功率。 2.The loadsabsorb electricenergy fromthe powersystem andconverts itinto energyof otherforms,
13、which maybe heatenergy toheat wateror tomelt irons,or mechanicalenergy todrive amachine,etc.负荷从电力系统中吸收电能，并将其转换为其他形式的能量，可能是烧水或溶化钢铁的热能，或者是驱动机器的机械能等。 负荷从电力系统中吸收电能，并将其转换为其他形式的能量，可能是烧水或溶化钢铁的热能，或者是驱动机器的机械能等。 9Lecture43.This kindof loads,especially thoseconsume energycalculated bystandard coalsmore over10t
14、housands oftons peryear,has aname ofhigh energyconsuming loads.这种负荷，尤其是那些年耗能万吨标准煤以上的负荷，被称为高耗能负荷。 这种负荷，尤其是那些年耗能万吨标准煤以上的负荷，被称为高耗能负荷。 New Wordsand Expressionshighenergyconsuming的高耗能的metallurgical冶金的settlement center结算中心intact完整无缺的agriculturalirrigation农业灌溉pressor压缩机refrigerator电冰箱oven烤箱，烤炉deep fryer煎锅i
15、ncandescent light白炽灯fluorescent light荧光灯converter转炉；变流器10Lecture4Part3Loads Modelsfor PowerSystem StudyAtypical loadbus is posed ofa largenumber ofdevices such as fluorescentand incandescentlamps,refrigerators,heaters,pressors,motors,furnaces,and soon.The exactposition ofload isdifficult toestimate.
16、Also,the positionchanges dependingon manyfactors includingtime(hour,day,and season),weather conditions,and stateof theeconomy.Even ifthe loadposition wereknown exactly,it wouldbe impracticalto representeach individualponent as there are usually millionsof suchponents in the totalload suppliedby apowersystem.Therefore,load representationin systemstudies isusually basedon aconsiderable amountof simplification.The loadmodels aretraditionally
