电气工程及其自动化外文翻译外文文献英文文献短路电流

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电气外文文献翻译

Circuit breaker断路器Compressed air circuit breaker is a mechanical switch equipment, can be i 空气压缩断路器是一种机械开关设备，能够在n normal and special conditions breaking current (such as short circuit cur 正常和特殊情况下开断电流（比如说短路电流）。

rent). For example, air circuit breaker, oil circuit breaker, interference circ 例如空气断路器、油断路器，干扰电路的导体uit conductor for the application of the safety and reliability of the circuit 干扰电路的导体因该安全可靠的应用于其中，breaker, current in arc from is usually divided into the following grades: a 电流断路器按灭弧远离通常被分为如下等级：ir switch circuit breaker, oil circuit breaker, less oil circuit breaker, compr 空气开关断路器、油断路器、少油断路器、压缩空essed air circuit breaker, a degaussing of isolating switch, six sulfur hexaf 气断路器、具有消磁性质的隔离开关、六氟luoride circuit breaker and vacuum breaker. Their parameters of voltage, 化硫断路器和真空断路器。

他们的参数有电压等级、current, insulation level of breaking capacity, instantaneous voltage off ti 开断容量的电流、绝缘等级开断时间的瞬时电压恢复和me of recovery and a bombing. Breaker plate usually include: 1 the maxi 轰炸时间。

电气工程及其自动化专业_外文文献_英文文献_外文翻译_plc方面.

1、外文原文A: Fundamentals of Single-chip MicrocomputerTh e si ng le -c hi p m ic ro co mp ut er i s t he c ul mi na ti on of both t h e de ve lo pm en t of the dig it al com pu te r an d th e in te gr at ed c i rc ui t arg ua bl y t h e tow m os t s ig ni f ic an t i nv en ti on s o f t he 20th c e nt ur y [1].Th es e tow type s of arch it ec tu re are foun d in sin g le -ch i p m i cr oc om pu te r. Som e empl oy the spli t prog ra m/da ta me mo ry of the H a rv ar d ar ch it ect u re , sh ow n in Fig.3-5A -1, oth ers fo ll ow the p h il os op hy , wi del y ada pt ed for gen er al -p ur po se com pu te rs and m i cr op ro ce ss o r s, o f ma ki ng no log i ca l di st in ct ion be tw ee n p r og ra m and dat a me mo ry as in the Pr in ce to n arch ite c tu re , show n i n Fig.3-5A-2.In gen er al ter ms a sin gl e -chi p mic ro co mp ut er i sc h ar ac te ri zed b y t he i nc or po ra ti on of a ll t he un it s of a co mp uter i n to a sin gl e d ev i ce , as sho wn inFi g3-5A -3.Fig.3-5A-1 A Harvard typeFig.3-5A-2. A conventional Princeton computerFig3-5A-3. Principal features of a microcomputerRead only memory (ROM.R OM is usua ll y for the pe rm an ent,n o n-vo la ti le stor a ge of an app lic a ti on s pr og ra m .M an ym i cr oc om pu te rs and m are inte nd e d for high -v ol um e ap pl ic at ions a n d he nc e t h e eco n om ic al man uf act u re of th e de vic e s re qu ir es t h at t he cont en t s o f t he prog ra m me m or y be co mm it t ed perm a ne ntly d u ri ng the man ufa c tu re of ch ip s .Cl ea rl y, thi s im pl ie s a r i go ro us app ro ach to ROM cod e deve l op me nt sin ce cha ng es can not b e mad e afte r manu f a c tu re .Th is dev e lo pm en t proc ess may invo lv e e m ul at io n us in g aso ph is ti ca te d de ve lo pm en t sy ste m wit h a h a rd wa re emu la tio n cap ab il it y as w el l as the use o f po we rf ul s o ft wa re too ls.So me man uf act u re rs pro vi de add it io na l RO M opt i on s by i n cl ud in g in their ra n ge dev ic es wit h (or int en de d fo r use wit h u s er pro gr am ma ble me mo ry. Th e sim p le st of th es e is usu al ly d e vi ce whi ch can op er at e in a micro p ro ce ssor mod e by usi ng som e o f the inp ut /outp u t li ne s as an ad dr es s an d da ta b us fora c ce ss in g ex te rna l mem or y. Thi s t y pe of de vi ce can beh av ef u nc ti on al ly as th e sing le chip mi cr oc om pu te r from whi ch it is d e ri ve d al be it wit h re st ri ct ed I/O and a mod if ied ex te rn al c i rc ui t. The use of thes e d ev ic es is com mo n eve n in prod uc ti on c i rc ui ts wher e t he vo lu me does no tj us ti f y t h e d ev el o pm en t c osts o f c us to m o n -ch i p R OM [2];t he re c a n s ti ll bea s ignif i ca nt saving i n I /O and o th er c h ip s com pa re d to a conv en ti on al mi c ro pr oc es sor b a se d ci rc ui t. Mor e ex ac t re pl ace m en t fo r RO M dev i ce s ca n be o b ta in ed in th e fo rm of va ri an ts w it h 'p ig gy -b ack 'E P RO M(Er as ab le pro gr am ma bl e ROM s oc ke ts or dev ic e s with EPROM i n st ea d o f RO M 。

电气工程与自动化毕业论文中英文资料外文翻译

电气工程与自动化毕业论文中英文资料外文翻译The Transformer on load ﹠Introduction to DC MachinesIt has been shown that a primary input voltage 1V can be transformed to any desired open-circuit secondary voltage 2E by a suitable choice of turns ratio. 2E is available for circulating a load current impedance. For the moment, a lagging power factor will be considered. The secondary current and the resulting ampere-turns 22N I will change the flux, tending to demagnetize the core, reduce m Φ and with it 1E . Because the primary leakage impedance drop is so low, a small alteration to 1Ewill cause an appreciable increase of primary current from 0I to a new value of 1Iequal to ()()i jX R E V ++111/. The extra primary current and ampere-turns nearly cancel the whole of the secondary ampere-turns. This being so , the mutual flux suffers only a slight modification and requires practically the same net ampere-turns 10N I as on no load. The total primary ampere-turns are increased by an amount 22N I necessary to neutralize the same amount of secondary ampere-turns. In thevector equation , 102211N I N I N I =+; alternatively, 221011N I N I N I -=. At full load,the current 0I is only about 5% of the full-load current and so 1I is nearly equalto 122/N N I . Because in mind that 2121/N N E E =, the input kV A which is approximately 11I E is also approximately equal to the output kV A, 22I E .The physical current has increased, and with in the primary leakage flux towhich it is proportional. The total flux linking the primary ,111Φ=Φ+Φ=Φm p , isshown unchanged because the total back e.m.f.,（dt d N E /111Φ-）is still equal and opposite to 1V . However, there has been a redistribution of flux and the mutual component has fallen due to the increase of 1Φ with 1I . Although the change is small, the secondary demand could not be met without a mutual flux and e.m.f.alteration to permit primary current to change. The net flux s Φlinking thesecondary winding has been further reduced by the establishment of secondaryleakage flux due to 2I , and this opposes m Φ. Although m Φ and 2Φ are indicatedseparately , they combine to one resultant in the core which will be downwards at theinstant shown. Thus the secondary terminal voltage is reduced to dt d N V S /22Φ-=which can be considered in two components, i.e. dt d N dt d N V m //2222Φ-Φ-=orvectorially 2222I jX E V -=. As for the primary, 2Φ is responsible for a substantiallyconstant secondary leakage inductance222222/Λ=ΦN i N . It will be noticed that the primary leakage flux is responsible for part of the change in the secondary terminal voltage due to its effects on the mutual flux. The two leakage fluxes are closely related; 2Φ, for example, by its demagnetizing action on m Φ has caused the changes on the primary side which led to the establishment of primary leakage flux.If a low enough leading power factor is considered, the total secondary flux and the mutual flux are increased causing the secondary terminal voltage to rise with load. p Φ is unchanged in magnitude from the no load condition since, neglecting resistance, it still has to provide a total back e.m.f. equal to 1V . It is virtually the same as 11Φ, though now produced by the combined effect of primary and secondary ampere-turns. The mutual flux must still change with load to give a change of 1E and permit more primary current to flow. 1E has increased this time but due to the vector combination with 1V there is still an increase of primary current.Two more points should be made about the figures. Firstly, a unity turns ratio has been assumed for convenience so that '21E E =. Secondly, the physical picture is drawn for a different instant of time from the vector diagrams which show 0=Φm , if the horizontal axis is taken as usual, to be the zero time reference. There are instants in the cycle when primary leakage flux is zero, when the secondary leakage flux is zero, and when primary and secondary leakage flux is zero, and when primary and secondary leakage fluxes are in the same sense.The equivalent circuit already derived for the transformer with the secondary terminals open, can easily be extended to cover the loaded secondary by the addition of the secondary resistance and leakage reactance.Practically all transformers have a turns ratio different from unity although such an arrangement is sometimes employed for the purposes of electrically isolating one circuit from another operating at the same voltage. To explain the case where 21N N ≠ the reaction of the secondary will be viewed from the primary winding. The reaction is experienced only in terms of the magnetizing force due to the secondary ampere-turns. There is no way of detecting from the primary side whether 2I is large and 2N small or vice versa, it is the product of current and turns which causesthe reaction. Consequently, a secondary winding can be replaced by any number of different equivalent windings and load circuits which will give rise to an identical reaction on the primary .It is clearly convenient to change the secondary winding to an equivalent winding having the same number of turns 1N as the primary.With 2N changes to 1N , since the e.m.f.s are proportional to turns, 2212)/('E N N E = which is the same as 1E .For current, since the reaction ampere turns must be unchanged 1222'''N I N I = must be equal to 22N I .i.e. 2122)/(I N N I =.For impedance , since any secondary voltage V becomes V N N )/(21, and secondary current I becomes I N N )/(12, then any secondary impedance, including load impedance, must becomeI V N N I V /)/('/'221=. Consequently,22212)/('R N N R = and 22212)/('X N N X = . If the primary turns are taken as reference turns, the process is called referring to the primary side.There are a few checks which can be made to see if the procedure outlined is valid.For example, the copper loss in the referred secondary winding must be the same as in the original secondary otherwise the primary would have to supply a differentloss power. ''222R I must be equal to 222R I . ）222122122/()/(N N R N N I •• does infact reduce to 222R I .Similarly the stored magnetic energy in the leakage field)2/1(2LI which is proportional to 22'X I will be found to check as ''22X I . The referred secondary 2212221222)/()/(''I E N N I N N E I E kVA =•==.The argument is sound, though at first it may have seemed suspect. In fact, if the actual secondary winding was removed physically from the core and replaced by the equivalent winding and load circuit designed to give the parameters 1N ,'2R ,'2X and '2I , measurements from the primary terminals would be unable to detect any difference in secondary ampere-turns, kVA demand or copper loss, under normal power frequency operation.There is no point in choosing any basis other than equal turns on primary andreferred secondary, but it is sometimes convenient to refer the primary to the secondary winding. In this case, if all the subscript 1’s are interchanged for the subscript 2’s, the necessary referring constants are easily found; e.g. 2'1R R ≈,21'X X ≈; similarly 1'2R R ≈ and 12'X X ≈.The equivalent circuit for the general case where 21N N ≠ except that m r hasbeen added to allow for iron loss and an ideal lossless transformation has been included before the secondary terminals to return '2V to 2V .All calculations of internal voltage and power losses are made before this ideal transformation is applied. The behaviour of a transformer as detected at both sets of terminals is the same as the behaviour detected at the corresponding terminals of this circuit when the appropriate parameters are inserted. The slightly different representation showing the coils 1N and 2N side by side with a core in between is only used for convenience. On the transformer itself, the coils are , of course , wound round the same core.Very little error is introduced if the magnetising branch is transferred to the primary terminals, but a few anomalies will arise. For example ,the current shown flowing through the primary impedance is no longer the whole of the primary current.The error is quite small since 0I is usually such a small fraction of 1I . Slightlydifferent answers may be obtained to a particular problem depending on whether or not allowance is made for this error. With this simplified circuit, the primary and referred secondary impedances can be added to give:221211)/(Re N N R R += and 221211)/(N N X X Xe +=It should be pointed out that the equivalent circuit as derived here is only valid for normal operation at power frequencies; capacitance effects must be taken into account whenever the rate of change of voltage would give rise to appreciablecapacitance currents, dt CdV I c /=. They are important at high voltages and atfrequencies much beyond 100 cycles/sec. A further point is not the only possible equivalent circuit even for power frequencies .An alternative , treating the transformer as a three-or four-terminal network, gives rise to a representation which is just as accurate and has some advantages for the circuit engineer who treats all devices as circuit elements with certain transfer properties. The circuit on this basiswould have a turns ratio having a phase shift as well as a magnitude change, and the impedances would not be the same as those of the windings. The circuit would not explain the phenomena within the device like the effects of saturation, so for an understanding of internal behaviour .There are two ways of looking at the equivalent circuit:(a) viewed from the primary as a sink but the referred load impedance connected across '2V ,or(b) viewed from the secondary as a source of constant voltage 1V with internal drops due to 1Re and 1Xe . The magnetizing branch is sometimes omitted in this representation and so the circuit reduces to a generator producing a constant voltage 1E (actually equal to 1V ) and having an internal impedance jX R + (actually equal to 11Re jXe +).In either case, the parameters could be referred to the secondary winding and this may save calculation time .The resistances and reactances can be obtained from two simple light load tests. Introduction to DC MachinesDC machines are characterized by their versatility. By means of various combination of shunt, series, and separately excited field windings they can be designed to display a wide variety of volt-ampere or speed-torque characteristics for both dynamic and steadystate operation. Because of the ease with which they can be controlled , systems of DC machines are often used in applications requiring a wide range of motor speeds or precise control of motor output.The essential features of a DC machine are shown schematically. The stator has salient poles and is excited by one or more field coils. The air-gap flux distribution created by the field winding is symmetrical about the centerline of the field poles. This axis is called the field axis or direct axis.As we know , the AC voltage generated in each rotating armature coil is converted to DC in the external armature terminals by means of a rotating commutator and stationary brushes to which the armature leads are connected. The commutator-brush combination forms a mechanical rectifier, resulting in a DCarmature voltage as well as an armature m.m.f. wave which is fixed in space. The brushes are located so that commutation occurs when the coil sides are in the neutral zone , midway between the field poles. The axis of the armature m.m.f. wave then in 90 electrical degrees from the axis of the field poles, i.e., in the quadrature axis. In the schematic representation the brushes are shown in quarature axis because this is the position of the coils to which they are connected. The armature m.m.f. wave then is along the brush axis as shown.. (The geometrical position of the brushes in an actual machine is approximately 90 electrical degrees from their position in the schematic diagram because of the shape of the end connections to the commutator.)The magnetic torque and the speed voltage appearing at the brushes are independent of the spatial waveform of the flux distribution; for convenience we shall continue to assume a sinusoidal flux-density wave in the air gap. The torque can then be found from the magnetic field viewpoint.The torque can be expressed in terms of the interaction of the direct-axis air-gapflux per pole d Φ and the space-fundamental component 1a F of the armature m.m.f.wave . With the brushes in the quadrature axis, the angle between these fields is 90 electrical degrees, and its sine equals unity. For a P pole machine 12)2(2a d F P T ϕπ=In which the minus sign has been dropped because the positive direction of thetorque can be determined from physical reasoning. The space fundamental 1a F ofthe sawtooth armature m.m.f. wave is 8/2π times its peak. Substitution in above equation then givesa d a a d a i K i m PC T ϕϕπ==2 Where a i =current in external armature circuit;a C =total number of conductors in armature winding;m =number of parallel paths through winding;Andm PC K aa π2=Is a constant fixed by the design of the winding.The rectified voltage generated in the armature has already been discussedbefore for an elementary single-coil armature. The effect of distributing the winding in several slots is shown in figure ,in which each of the rectified sine waves is the voltage generated in one of the coils, commutation taking place at the moment when the coil sides are in the neutral zone. The generated voltage as observed from the brushes is the sum of the rectified voltages of all the coils in series between brushesand is shown by the rippling line labeled a e in figure. With a dozen or socommutator segments per pole, the ripple becomes very small and the average generated voltage observed from the brushes equals the sum of the average values ofthe rectified coil voltages. The rectified voltage a e between brushes, known also asthe speed voltage, ism d a m d a a W K W m PC e ϕϕπ==2 Where a K is the design constant. The rectified voltage of a distributed winding has the same average value as that of a concentrated coil. The difference is that the ripple is greatly reduced.From the above equations, with all variable expressed in SI units:m a a Tw i e =This equation simply says that the instantaneous electric power associated with the speed voltage equals the instantaneous mechanical power associated with the magnetic torque , the direction of power flow being determined by whether the machine is acting as a motor or generator.The direct-axis air-gap flux is produced by the combined m.m.f. f f i N ∑ of the field windings, the flux-m.m.f. characteristic being the magnetization curve for the particular iron geometry of the machine. In the magnetization curve, it is assumed that the armature m.m.f. wave is perpendicular to the field axis. It will be necessary to reexamine this assumption later in this chapter, where the effects of saturation are investigated more thoroughly. Because the armature e.m.f. is proportional to flux times speed, it is usually more convenient to express the magnetization curve in termsof the armature e.m.f. 0a e at a constant speed 0m w . The voltage a e for a given fluxat any other speed m w is proportional to the speed,i.e. 00a m m a e w w e =Figure shows the magnetization curve with only one field winding excited. This curve can easily be obtained by test methods, no knowledge of any design details being required.Over a fairly wide range of excitation the reluctance of the iron is negligible compared with that of the air gap. In this region the flux is linearly proportional to the total m.m.f. of the field windings, the constant of proportionality being the direct-axis air-gap permeance.The outstanding advantages of DC machines arise from the wide variety of operating characteristics which can be obtained by selection of the method of excitation of the field windings. The field windings may be separately excited from an external DC source, or they may be self-excited; i.e., the machine may supply its own excitation. The method of excitation profoundly influences not only the steady-state characteristics, but also the dynamic behavior of the machine in control systems.The connection diagram of a separately excited generator is given. The required field current is a very small fraction of the rated armature current. A small amount of power in the field circuit may control a relatively large amount of power in the armature circuit; i.e., the generator is a power amplifier. Separately excited generators are often used in feedback control systems when control of the armature voltage over a wide range is required. The field windings of self-excited generators may be supplied in three different ways. The field may be connected in series with the armature, resulting in a shunt generator, or the field may be in two sections, one of which is connected in series and the other in shunt with the armature, resulting in a compound generator. With self-excited generators residual magnetism must be present in the machine iron to get the self-excitation process started.In the typical steady-state volt-ampere characteristics, constant-speed primemovers being assumed. The relation between the steady-state generated e.m.f. a Eand the terminal voltage t V isa a a t R I E V -=Where a I is the armature current output and a R is the armature circuitresistance. In a generator, a E is large than t V ; and the electromagnetic torque T is acountertorque opposing rotation.The terminal voltage of a separately excited generator decreases slightly with increase in the load current, principally because of the voltage drop in the armature resistance. The field current of a series generator is the same as the load current, so that the air-gap flux and hence the voltage vary widely with load. As a consequence, series generators are not often used. The voltage of shunt generators drops off somewhat with load. Compound generators are normally connected so that the m.m.f. of the series winding aids that of the shunt winding. The advantage is that through the action of the series winding the flux per pole can increase with load, resulting in a voltage output which is nearly constant. Usually, shunt winding contains many turns of comparatively heavy conductor because it must carry the full armature current of the machine. The voltage of both shunt and compound generators can be controlled over reasonable limits by means of rheostats in the shunt field. Any of the methods of excitation used for generators can also be used for motors. In the typical steady-state speed-torque characteristics, it is assumed that the motor terminals are supplied froma constant-voltage source. In a motor the relation between the e.m.f. a E generated inthe armature and the terminal voltage t V isa a a t R I E V +=Where a I is now the armature current input. The generated e.m.f. a E is nowsmaller than the terminal voltage t V , the armature current is in the oppositedirection to that in a motor, and the electromagnetic torque is in the direction to sustain rotation of the armature.In shunt and separately excited motors the field flux is nearly constant. Consequently, increased torque must be accompanied by a very nearly proportional increase in armature current and hence by a small decrease in counter e.m.f. to allow this increased current through the small armature resistance. Since counter e.m.f. is determined by flux and speed, the speed must drop slightly. Like the squirrel-cage induction motor ,the shunt motor is substantially a constant-speed motor having about 5 percent drop in speed from no load to full load. Starting torque and maximum torque are limited by the armature current that can be commutatedsuccessfully.An outstanding advantage of the shunt motor is ease of speed control. With a rheostat in the shunt-field circuit, the field current and flux per pole can be varied at will, and variation of flux causes the inverse variation of speed to maintain counter e.m.f. approximately equal to the impressed terminal voltage. A maximum speed range of about 4 or 5 to 1 can be obtained by this method, the limitation again being commutating conditions. By variation of the impressed armature voltage, very wide speed ranges can be obtained.In the series motor, increase in load is accompanied by increase in the armature current and m.m.f. and the stator field flux (provided the iron is not completely saturated). Because flux increases with load, speed must drop in order to maintain the balance between impressed voltage and counter e.m.f.; moreover, the increase in armature current caused by increased torque is smaller than in the shunt motor because of the increased flux. The series motor is therefore a varying-speed motor with a markedly drooping speed-load characteristic. For applications requiring heavy torque overloads, this characteristic is particularly advantageous because the corresponding power overloads are held to more reasonable values by the associated speed drops. Very favorable starting characteristics also result from the increase in flux with increased armature current.In the compound motor the series field may be connected either cumulatively, so that its.m.m.f.adds to that of the shunt field, or differentially, so that it opposes. The differential connection is very rarely used. A cumulatively compounded motor has speed-load characteristic intermediate between those of a shunt and a series motor, the drop of speed with load depending on the relative number of ampere-turns in the shunt and series fields. It does not have the disadvantage of very high light-load speed associated with a series motor, but it retains to a considerable degree the advantages of series excitation.The application advantages of DC machines lie in the variety of performance characteristics offered by the possibilities of shunt, series, and compound excitation. Some of these characteristics have been touched upon briefly in this article. Stillgreater possibilities exist if additional sets of brushes are added so that other voltages can be obtained from the commutator. Thus the versatility of DC machine systems and their adaptability to control, both manual and automatic, are their outstanding features.中文翻译负载运行的变压器及直流电机导论通过选择合适的匝数比，一次侧输入电压1V 可任意转换成所希望的二次侧开路电压2E 。

电气工程及其自动化专业外文文献英文文献外文翻译 plc方面

1、外文原文（复印件）A: Fundamentals of Single-chip MicrocomputerTh e si ng le-ch i p mi cr oc om pu ter is t he c ul mi nat i on o f bo th t h e d ev el op me nt o f th e d ig it al com p ut er an d t he int e gr at ed ci rc ui ta r gu ab ly th e t ow m os t s i gn if ic ant i nv en ti on s o f t h e 20t h c en tu ry[1].Th es e to w typ e s of a rc hi te ctu r e ar e fo un d i n s in gl e-ch ip m i cr oc om pu te r. So m e em pl oy t he sp l it p ro gr am/d ata me mo ry o f th e H a rv ar d ar ch it ect u re, sh ow n i n -5A, ot he rs fo ll ow th e ph i lo so ph y, w i de ly a da pt ed fo r g en er al-p ur pos e c om pu te rs an d m i cr op ro ce ss or s, o f m a ki ng no lo gi c al di st in ct io n b e tw ee n p ro gr am a n d da t a m em ory a s i n th e Pr in cet o n ar ch it ec tu re,sh ow n in-5A.In g en er al te r ms a s in gl e-chi p m ic ro co mp ut er i sc h ar ac te ri zed b y the i nc or po ra tio n of al l t he uni t s o f a co mp ut er i n to a s in gl e dev i ce, as s ho wn in Fi g3-5A-3.-5A-1 A Harvard type-5A. A conventional Princeton computerFig3-5A-3. Principal features of a microcomputerRead only memory (ROM).R OM i s u su al ly f or th e p er ma ne nt, n o n-vo la ti le s tor a ge o f an a pp lic a ti on s pr og ra m .M an ym i cr oc om pu te rs an d mi cr oc on tr ol le r s a re in t en de d fo r h ig h-v ol ume a p pl ic at io ns a nd h en ce t he e co nom i ca l ma nu fa ct ure of t he d ev ic es r e qu ir es t ha t the co nt en ts o f the pr og ra m me mo ry b e co mm it te dp e rm an en tl y d ur in g th e m an uf ac tu re o f c hi ps . Cl ear l y, th is im pl ie sa ri g or ou s a pp roa c h t o R OM co de d e ve lo pm en t s in ce c ha ng es ca nn otb e m ad e af te r man u fa ct ur e .T hi s d e ve lo pm en t pr oce s s ma y in vo lv e e m ul at io n us in g a s op hi st ic at ed deve lo pm en t sy st em w i th a ha rd wa re e m ul at io n ca pa bil i ty a s we ll a s th e u se of po we rf ul so ft wa re t oo ls.So me m an uf act u re rs p ro vi de ad d it io na l RO M opt i on s byi n cl ud in g i n th ei r ra ng e de vi ce s wi th (or i nt en de d fo r us e wi th) u s er pr og ra mm ab le m em or y. Th e s im p le st of th es e i s us ua ll y d ev ice w h ic h ca n op er ate in a m ic ro pr oce s so r mo de b y usi n g so me o f th e i n pu t/ou tp ut li ne s as a n ad dr es s an d da ta b us f or acc e ss in g e xt er na l m e mo ry. T hi s t ype o f d ev ic e c an b e ha ve fu nc ti on al l y a s t he si ng le c h ip mi cr oc om pu te r fr om wh ic h i t i s de ri ve d a lb eit w it h r es tr ic ted I/O an d a mo di fie d e xt er na l ci rcu i t. T he u se o f t h es e RO Ml es sd e vi ce s is c om mo n e ve n in p ro du ct io n c ir cu it s wh er e t he v ol um e do es n o t ju st if y th e d e ve lo pm en t co sts of c us to m on-ch i p RO M[2];t he re c a n st il l b e a si g ni fi ca nt s a vi ng in I/O a nd ot he r c hi ps co mp ar ed t o a c on ve nt io nal mi cr op ro ce ss or b as ed c ir cu it. M o re e xa ctr e pl ac em en t fo r RO M d ev ic es c an b e o bt ai ne d in t he f o rm o f va ri an ts w i th 'pi gg y-ba ck'EP RO M(Er as ab le p ro gr am ma bl e ROM)s oc ke ts o rd e vi ce s w it h EP ROM i ns te ad o f R OM 。

电气工程及其自动化外文翻译

A minimum electric power system is shown in Fig.1-1, the system consists of an energy source, a prime mover, a generator, and a load.The energy source may be coal, gas, or oil burned in a furnace to heat water and generate steam in a boiler; it may be fissionable material which, in a nuclear reactor, will heat water to produce steam; it may be water in a pond at an elevation above the generating station; or it may be oil or gas burned in an internal combustion engine.The prime mover may be a steam-driven turbine, a hydraulic turbine or water wheel, or an internal combustion engine. Each one of these prime movers has the ability to convert energy in the form of heat, falling water, or fuel into rotation of a shaft, which in turn will drive the generator.The electrical load on the generator may be lights, motors, heaters, or other devices, alone or in combination. Probably the load will vary from minute to minute as different demands occur.The control system functions (are) to keep the speed of the machines substantially constant and the voltage within prescribed limits, even though the load may change. To meet these load conditions, it is necessary for fuel input to change, for the prime mover input to vary, and for torque on the shaft from the prime mover to change in order that the generator may be kept at constant speed. In addition, the field current to the generator must be adjusted to maintain constant output voltage. The control system may include a man stationed in the power plant who watches a set of meters on the generator output terminals and makes the necessary adjustments manually. In a modern station, the control system is a servomechanism that senses generator-output conditions and automatically makes the necessary changes in energy input and field current to hold the electrical output within certain specifications.In most situations the load is not directly connected to the generator terminals. More commonly the load is some distance from the generator, requiring a power line connecting them. It is desirable to keep the electric power supply at the load within specifications. However, the controls are near the generator, which may be in another building, perhaps several miles away.If the distance from the generator to the load is considerable, it may be desirable to install transformers at the generator and at the load end, and to transmit the power over a high-voltage line (Fig.1-2). For the same power, the higher-voltage line carries less current, has lower losses for the same wire size, and provides more stable voltage.In some cases an overhead line may be unacceptable. Instead it may be advantageous to use an underground cable. With the power systems talked above, the power supply to the load must be interrupted if, for any reason, any component of the system must be moved from service for maintenance or repair. Additional system load may require more power than the generator can supply. Another generator with its associated transformers and high-voltage line might be added.It can be shown that there are some advantages in making ties between the generators (1) and at the end of the high-voltage lines (2 and 3), as shown in Fig.1-3. This system will operate satisfactorily as long as no trouble develops or no equipment needs to be taken out of service.The above system may be vastly improved by the introduction of circuit breakers, which may be opened and closed as needed. Circuit breakers added to the system, Fig.1-4, permit selected piece of equipment to switch out of service without disturbing the remainder of system. With this arrangement any element of the system may be deenergized for maintenance or repair by operation of circuit breakers.Of course, if any piece of equipment is taken out of service, then the total load mustbe carried by the remaining equipment. Attention must be given to avoid overloads during such circumstances. If possible, outages of equipment are scheduled at times when load requirements are below normal.Fig.1-5 shows a system in which three generators and three loads are tied together by three transmission lines. No circuit breakers are shown in this diagram, although many would be required in such a system.Part 3 Typical System LayoutThe generators, lines, and other equipment which form an electric system are arranged depending on the manner in which load grows in the area and may be rearranged from time to time.However, there are certain plans into which a particular system design may be classified. Three types are illustrated: the radial system, the loop system, and the network system. All of these are shown without the necessary circuit breakers. In eachof these systems, a single generator serves four loads.The radial system is shown in Fig.1-6. Here the lines form a “tree” spre t ing from the generator. Opening any line results in interruption of power to one or more of the loads.The loop system is illustrated in Fig.1-7. With this arrangement all loads may be served even though one line section is removed from service. In some instances during normal operation, the loop may be open at some point, such as A. In case a line section is to be taken out, the loop is first closed at A and then the line section removed. In this manner no service interruptions occur.Fig.1-8 shows the same loads being served by a network. With this arrangement each load has two or more circuits over which it is fed.Distribution circuits are commonly designed so that they may be classified as radial or loop circuits. The high-voltage transmission lines of most power systems are arranged as network. The interconnection of major power system results in networks made up by many line sections.Part 4 Auxiliary EquipmentCircuit breakers are necessary to deenergize equipment either for normal operation or on the occurrence of short circuits. Circuit breakers must be designed to carry normal-load currents continuously, to withstand the extremely high currents that occur during faults, and to separate contacts and clear a circuit in the presence of fault. Circuit breakers are rated in terms of these duties.When a circuit breaker opens to deenergize a piece of equipment, one side ofthe circuit breaker usually remains energized, as it is connected to operating equipment. Since it is sometimes necessary to work on the circuit breaker itself, it is also necessary to have means by which the circuit breaker may be completely disconnected from other energized equipment. For this purpose disconnect switches are placed in series with the circuit breakers. By opening these disconnectors, the circuit breaker may be completely deenergized, permitting work to be carried on in safety.Various instruments are necessary to monitor the operation of the electric power system. Usually each generator, each transformer bank, and each line has its own set of instruments, frequently consisting of voltmeters, ammeters, wattmeters, and varmeters.When a fault occurs on a system, conditions on the system undergo a sudden change. Voltages usually drop and currents increase. These changes are most noticeable in the immediate vicinity of fault. On-line analog computers, commonly called relays, monitor these changes of conditions, make a determination of which breaker should be opened to clear the fault, and energize the trip circuits of those appropriate breakers. With modern equipment, the relay action and breaker opening causes removal of fault within three or four cycles after its initiation.The instruments that show circuit conditions and the relays that protect the circuits are not mounted directly on the power lines but are placed on switchboards in a control house. Instrument transformers are installed on the high-voltage equipment, by means of which it is possible to pass on to the meters and relays representative samples of the conditions on the operating equipment. The primary of a potential transformer is connected directly to the high-voltage equipment. The secondary provides for the instruments and relays a voltage which is a constant fraction of voltage on the operating equipment and is in phase with it；similarly, a current transformer is connected with its primary in the high-current circuit. The secondary winding provides a current that is a known fraction of the power-equipment current and is in phase with it.Bushing potential devices and capacitor potential devices serve the same purpose as potential transformers but usually with less accuracy in regard to ratio and phase angle.中文翻译：电力系统的简介一个最小电力系统如图 1-1 所示，系统包含动力源，原动机，发机电和负载。

电气工程及其自动化专业外文文献英文文献外文翻译方面

1、外文原文（复印件）A: Fundamentals of Single-chip MicrocomputerT h e sin gle -ch ip mi c ro co m p u t e r is t h e cu lm in at io n of b ot h t h e d e ve lo p me nt of t h e d ig ita l co m p u t e r a n d t h e i nte g rated c ircu it a rgu ab l y t h e to w mo st s ign if i cant i nve nt i o n s of t h e 20t h c e nt u ry [1].T h ese to w t yp e s of arch ite ct u re are fo u n d in s in gle -ch ip m i cro co m p u te r. S o m e e mp l oy t h e sp l it p ro gra m /d at a m e m o r y of t h e H a r va rd arch ite ct u re , s h o wn in -5A , ot h e rs fo l lo w t h e p h i lo so p hy, wid e l y ad a p ted fo r ge n e ral -p u rp o se co m p u te rs an d m i cro p ro ce ss o rs , of m a kin g n o l o g i ca l d i st in ct i o n b et we e n p ro gra m an d d ata m e m o r y as in t h e P rin c eto n a rch ite ct u re , sh o wn in -5A.In ge n e ra l te r m s a s in g le -ch ip m ic ro co m p u t e r is ch a ra cte r ized b y t h e in co r p o rat io n of all t h e u n its of a co mp u te r into a s in gle d e vi ce , as s h o w n in F i g3-5A-3.-5A-1A Harvard type-5A. A conventional Princeton computerProgrammemory Datamemory CPU Input& Output unitmemoryCPU Input& Output unitResetInterruptsPowerFig3-5A-3. Principal features of a microcomputerRead only memory (ROM).RO M is u su a l l y fo r t h e p e r m an e nt , n o n -vo lat i le sto rage of an ap p l i cat io n s p ro g ram .M a ny m i c ro co m p u te rs a n d m i cro co nt ro l le rs are inte n d ed fo r h i gh -vo lu m e ap p l i cat io n s a n d h e n ce t h e e co n o m i cal man u fa c t u re of t h e d e vi ces re q u ires t h at t h e co nt e nts of t h e p ro gra m me mo r y b e co mm i ed p e r m a n e nt l y d u r in g t h e m a n u fa ct u re of c h ip s . C lea rl y, t h i s imp l ies a r i go ro u s ap p ro a ch to ROM co d e d e ve lo p m e nt s in ce ch an ges can n o t b e mad e af te r m an u fa ct u re .T h i s d e ve l o p m e nt p ro ces s m ay i nvo l ve e mu l at i o n u sin g a so p h ist icated d e ve lo p m e nt syste m wit h a h ard wa re e mu l at i o n capab i l it y as we ll as t h e u s e of p o we rf u l sof t war e to o l s.So m e m an u fa ct u re rs p ro vi d e ad d it i o n a l ROM o p t io n s b y in clu d in g in t h e i r ran ge d e v ic es w it h (o r inte n d ed fo r u s e wit h ) u se r p ro g ram m a b le m e mo r y. T h e s im p lest of t h e se i s u su a l l y d e v i ce wh i ch can o p e rat e in a m i cro p ro ce s so r mo d e b y u s in g s o m e of t h e in p u t /o u t p u t l in es as an ad d res s a n d d ata b u s fo r a cc es sin g exte rn a l m e m o r y. T h is t yp e o f d e vi ce can b e h ave f u n ct i o n al l y as t h e s in gle ch ip m i cro co m p u t e r f ro m wh i ch it i s d e ri ved a lb e it wit h re st r icted I/O an d a m o d if ied exte rn a l c ircu it. T h e u s e of t h e se RO M le ss d e vi ces i s co mmo n e ve n in p ro d u ct io n circu i ts wh e re t h e vo lu m e d o e s n ot ju st if y t h e d e ve lo p m e nt co sts of cu sto m o n -ch ip ROM [2];t h e re ca n st i ll b e a si gn if i cant sav in g in I/O an d o t h e r ch ip s co m pared to a External Timing components System clock Timer/ Counter Serial I/O Prarallel I/O RAM ROMCPUco nve nt io n al m i c ro p ro ces so r b ased circ u it. M o re exa ct re p l a ce m e nt fo rRO M d e v ice s can b e o b tain ed in t h e fo rm of va ria nts w it h 'p i g g y-b a c k'E P ROM(E rasab le p ro gramm ab le ROM )s o cket s o r d e v ice s w it h E P ROMin stead of ROM 。

电气外文文献-翻译

电气工程及其自动化专业英语课文翻译

unit1 taxe A 电力变压器的结构和原理在许多能量转换系统中，变压器是一个不了缺少的原件。

它使得在经济的发电机所产生电能并以最经历的传输电压传输电能，同时对于特定的使用者合适的电压使用电能成为可能。

变压器同样广泛的应用于低功率低电流的电子电路和控制电路中，来执行像匹配电源组抗和负载以求得最大的传输效率。

隔离一个电路与另一个电路在两个电路之间隔离直流电而保证交流电继续通道的功能。

在本质上，变压器是一个由两个或多个绕组通过相互的磁通耦合而组成的，如果这其中的一个绕组，原边连接到交流电压源将产生交流磁通它的幅值决定于原边的电压所提供的电压频率及匝数。

感应磁通将与其他绕组交链，在副边中将感应出一个电压其幅值将取决于副边的匝数及感应磁通量和频率。

通过使原副边匝数比例适应，任何所期望的电压比例或转换比例都可以得到。

变压器工作的本质仅要求存在与两个绕组相交链的时变的感应磁通。

这样的作用也可以发生在通过空气耦合的两组绕组中，但用铁心或其他铁磁材料可以使绕组之间的耦合作用增强，因为一大部分磁通被限制在与两个绕组交链的高磁导率的路径中。

这种变压器通常被称作为心式变压器。

大部分变压器都是这种类型。

以下的讨论几乎全部围绕心事变压器。

为减少铁心中的涡流所产生的损耗，磁路通常由一叠薄的叠片所组成。

如图1.1所示两种常见的结构形式用示意图表示出来。

芯式变压器的绕组绕在两个矩形铁心柱上，壳式变压器的绕组绕在三个铁心柱中间的那个铁心柱上，。

0.14毫米厚的硅钢片通常被用于在低频率低于几百Hz下运行的变压器中，硅钢片具有价格低铁心损耗小，在高磁通密度下，磁导率高的理想性能，能用做高频率低能耗的标准的通讯电路中的小型变压器的铁心是由被称为铁氧体的粉末压缩制成的铁磁合金所构成的。

在这些结构中，大部分的磁通被限制在固定的铁心中与两个绕组相交链。

绕组也产生多余的磁通，像漏磁通，只经过一个绕组和另外的绕组不相交链。

虽然漏磁通只是所有磁通的一小部分，但它在决定变压器的运行情况中起着重要的作用。

电气工程及其自动化外文翻译

The micro structure of low voltage distribution system BACKGROUND OF THE INVENTION1. Field of the InventionThis invention relates to a novel and unique low voltage distribution system to wire a miniature structure with an electrical circuit which cooperates with bi-prong electrical fastening members which function as an electrical connector to plug an electric light bulb to the electrical circuit in the miniature structure. In particular, this invention relates to an easily installed electrical wiring system using an adhesive backed conductive foil tape as the bus bar for the system. The bi-prong electrical fastening devices can be plugged into and unplugged from the bus bar strips at any desired location.2. Disclosure of the Prior ArtIt is known in the art to utilize low voltage lighting systems for miniature structures. Typically, the wiring takes the form of insulated electrical conductors extending from a voltage source, such as a battery or step-down transformer, directly to a light bulb. Each light has its own pair of conductors which extend throughout the miniature structure.It is also known to install wiring within a miniature structure in the form of a distribution circuit having a plurality of junctions or connecting points wherein conductors are electrically connected at the connecting points by a soldered connection. Addition of a lamp or relocating a lamp requires soldering or mechanically disconnecting the lamp.Other known low voltage distribution systems utilize electrical connectors having female and male components. Other systems utilize a variety of electrical conductors and connecting devices, all of which require tools or following precise installation techniques.SUMMARY OF THE INVENTIONThe novel and unique low voltage distribution system for miniature structures, such as doll houses or other model buildings, of the present invention overcomes several disadvantages of the prior art. One advantage of the present invention is that a main bus bar for the distribution system is formed by a pair of elongated bus bar strips having a conductive metal foil top layer and an adhesive bottom layer. The strips are easily installed by peeling off a removable backing member exposing the adhesive layer. The bus bar strips are affixed to the walls of the miniature structure in a parallel spaced relationship. The distance between the center line of the strips is selected to be a predetermined distance. The predetermined distance is at least equal to the transverse width or geometrical dimension of the strips. Bi-prong electrical fastening devices having two sharp points are pushed into the bus bar, pierce and pass through the parallel strips, forming an electrical connection with the strips. The points engage the wall of the miniature structure and are held in place. A light bulb is connected by wires across the bi-prong plug.Another advantage is that the bus bar strips are easily formed into 90° angles or other angles by folding the strips to obtain the desired angle. Prior art devices require staples or adhesive holding devices to hold insulating wires. Depending on thedistribution system of the prior art devices, an electrical connection requires tools, soldering or some method of insuring a dependable mechanical and electrical connection.Another advantage of the present invention is that the bi-prong electrical fastening device is easily installed by pushing the device into the miniature structure wall in the same manner as a tack of similar device. If it is desired to remove or relocate a lamp, the bi-prong plug is easily pulled out and reinserted.Yet another advantage of the present invention is that branch bus bar circuits can be fabricated by folding the end against itself forming a mating terminal. The mating terminal is placed into contact at any desired location on the main bus bar to form sub-distribution circuits.A yet further advantage of the present invention is that a lamp can be attached to a bi-prong plug by winding wires together and forming a tight insulating seal therearound by use of a heat-shrinkable tube or cylinder.BRIEF DESCRIPTION OF THE DRAWINGThe foregoing and other advantages and features of the invention will be apparent from the following description of the preferred embodiment of the invention when considered together with the illustrations in the accompanying drawings and includes the following figures:FIG. 1 is a schematic diagram showing the low voltage distribution system having bi-prong plugs and lamp connected thereto;FIG. 2 is a perspective view of a contacting mating connection between a main bus bar and a branch bus bar;FIG. 3 is a pictorial representation of a doll house having a pair of spaced parallel elongated strips as the main bus bar and branch bus bar;FIG. 4 is a diagrammatic representation of a section of bus bar having a bi-prong electrical fastening device inserted therein;FIG. 5 is a section taken along section lines 5-5 of FIG. 4;FIGS. 6, 7 and 8 are an end, front and top view of a bi-prong electrical fastening device having a circular cross-section;FIGS. 9, 10 and 11 are an end, front and top view of a bi-prong electrical fastening device having a rectangular cross-section;FIG. 12 is a pictorial illustration of twisting an end of a conductor from a bi-prong electrical fastening device with the end of a conductor from a light bulb having a heat shrinkable tube strung on the conductors; andFIG. 13 is a wire lamp and bi-prong electrical fastening device with the heat-shrinkable sealing tube being shrunk to form a tight insulating seal around the twisted electrical connection illustrated in FIG. 12.DESCRIPTION OF THE PREFERRED EMBODIMENTThe schematic diagram of FIG. 1 includes a means for producing a low voltage signal such as, for example, a step down transformer 20. In the preferred embodiment, a primary winding 22 of transformer 20 is electrically connected across a 120 volt 60 hertz source. A secondary winding 24 produces a low voltage, 60 hertz signal thereacross such as 12 volts A.C. The low voltage source could be a direct currentsource such as batteries.The transformer 20 may include a detecting and limiting device 28 to detect and limit the current flow through the secondary winding 24. If the transformer becomes overloaded due to high current flow, the device 28 opens. A thermal cutout may be used as one such device. The transformer may be a 120/12 volt 60 hertz U.L. approved Class 2 transformer.A main bus bar, shown generally as 30, is electrically connected to the secondary winding 24 by electrical conductors 32.A branch bus bar, shown generally as 36, is attached or connected to the main bus bar30 through a pair of mating contacts shown as 40 and 42.Bi-prong electrical fastening devices shown as 50 are inserted into the bus bar to make electrical contact. Each bi-prong plug 50 has a lamp 52 connected thereto. The connections are made through sealed electrical connectors 54.FIG. 2 illustrates the main bus bar 30 is formed of two spaced parallel strips 56 and 58 each having a conductive metal foil top layer 60 and an adhesive bottom layer 62. The width of the strip is of a selected geometrical dimension. The bus bar's two elongated strips 56 and 58 are spaced with the center lines 64 and 66, respectively, spaced a predetermined distance. The predetermined distance, in the preferred embodiment, is at least equal to the width of strips 56 and 58.A branch bus bar having two elongated strips 70 and 72, which is of the same material and construction as strips 56 and 58, has the one end thereof folded back upon itself with the adhesive layer of the folded end in contact with and adhering to the adhesive layer of the unfolded bus bar strip to form coplanar mating contacts 74 and 76. The coplanar mating contacts 74 and 76 are in mating electrical contact with the conductive metal top foil 60. Pieces of adhesive tape 80 are affixed to mating contacts 74 and 76, and a piece of adhesive tape 82 is located between strips 56 and 72. A section of the miniature structure is shown as 86.FIG. 3 shows a miniature structure 90 having a main bus bar 92 and a branch bus bar 94. The mating connection is shown as 96. Several right angle turns in the bus bar are shown by 100. A typical wiring pattern extends through three stories.FIG. 4 shows a top view of a section 104 of the miniature structure having bus bar strips 56 and 58 adhered thereto. The strips 56 and 58 originally and a protective backing which was removed exposing the adhesive. A bi-prong electrical connecting 50 device has conductive fastening members 120 (shown in FIGS. 5 through 8) terminating in an output terminal 108. A pair of insulated electrical conductors 110 is attached to output terminal 108.An end sectional view of the bus bar strips 56 and 58 and bi-prong electrical connecting device 50 in FIG. 5 shows that the conductive fastening members 120 terminate in a tapered cutting edge or point 122 adapted to pierce and be driven through the bus bar forming an electrical connection therewith and into fastening engagement with a selected portion 104 of the miniature structure.The conductive fastening members 120 are spaced a predetermined distance apart and are parallel to each other. Each conductive fastening member 120 terminates in an output terminal 108 having conductors 110 soldered thereto. The housing or body 124of the bi-prong plug 50 is formed of insulating, cured epoxy well known in the art. FIGS. 6, 7 and 8 show a bi-prong electrical fastening member having a circular cross-section. The elements are shown in solid line with the body 124 shown in dashed line.FIGS. 9, 10 and 11 show a bi-prong electrical fastening member having a rectangular cross-section. The elements are shown in solid line with the body 124 shown in dashed line.FIG. 12 shows an electrical conductor 110 with a conductive end section 126 exposed and twisted together with the end of a conducting lead 128 from a lamp or light bulb 52. A heat-shrinkable tube or cylinder 130 is positioned around each joined connection of the conducting lead 128 and electrical conductor 110. The tube 130 has an axial length sufficient to encapsulate and form a tight, insulating fitting around the connection. FIG. 13 shows the tube 130 and wiring being exposed to a heat source 142 of the right temperature to cause the desired shrinkage.The system disclosed herein can be assembled into a lighting kit for use in a doll house or for other miniature structures such as that used with model trains, model cities and other hobby type structures. In the preferred embodiment, the kit comprises a transformer, copper tape with an adhesive backing, light bulbs, wires, spring clamps (used as connecting means 32 in FIG. 1) and heat shrinkable tubing.The connections for providing a 12 volt electrical signal from the two copper tapes and into a lamp or fixture in the structure is obtained by attaching one of the bi-prong plugs to the bulbs or lamps. The two prongs of the plug are pointed and are pressed into and through the copper tapes in a manner similar to insertion and removal of a two-prong fastener.Installation of the distribution system is fairly simple and can be done without use of tools or soldering equipment. This is of significance in the model or hobby market.It is also envisioned that the connecting means in FIG. 1 may well be a bi-prong electrical connecting device wherein the electrical conductors are connected to the output of the transformer.What is claimed is:1. A low voltage distribution system for a miniature structure comprisingmeans for producing a low voltage signal;a main bus bar formed of a conductive metal foil top layer and an adhesive bottom layer, said conductive metal foil having a pair of elongated bus bar strips each having a selected geometrical dimension across the width thereof, said strips being positioned in spaced parallel relationship wherein the spacing between the parallel center lines of each elongated bus bar strip is of a predetermined distance which is at least equal to said geometrical dimension and said adhesive layer being adapted to attach the main bus bar to a selected portion of a miniature structure with the conductive metal foil exposed;means for connecting the low voltage signal to the conductive metal foil layer and producing a voltage potential across said strips; andat least one bi-prong removable electrical fastening device formed of a pair of spacedconductive fastening members each of which are electrically connected to an output terminal, each of said fastening members terminating in an elongated tapered cutting edge, said tapered cutting edges being in spaced parallel relationship and having a dimension therebetween substantially equal to said predetermined distance, and which, when urged into fastening engagement with a said miniature structure, are adapted to pierce, form an elongated slit in and parallel to the center line of each bus bar and be driven through each of the bus bar strips of the main bus bar forming an electrical connection therewith and into fastening engagement with said selected portion of a said miniature structure located under the adhesive layer, and being adapted to terminate said electrical connection with each of the bus bar strips upon removal of the fastening member from fastening engagement with said selected portion of a miniature structure by slideably withdrawing the tapered edges from each bus bar strip leaving a slight elongated slit therein while enabling the strips to maintain a voltage potential thereacross independent of the elongated slit.2. The system of claim 1 wherein the means for producing a low voltage signal comprises a step down alternating current transformer.3. The system of claim 2 wherein the low voltage signal producing means includes means for detecting and limiting the current flow through the step down transformer.4. The system of claim 3 wherein the low voltage signal connecting means includesa pair of transformer leads; anda pair of spring clips electrically connected to the transformer leads and to the main bus bar.5. The system of claim 1 whereinsaid bi-prong electrical fastening device includes a pair of separate output terminals electrically connected to said spaced fastening members and having a geometrical distance therebetween which is substantially equal to said predetermined distance.6. The system of claim 5 further comprisinga second bi-prong electrical fastening device identical to said at least one bi-prong electrical fastening device and adapted to pierce and be driven through a different section of the main bus bar forming an electrical connection therewith and into fastening engagement with a selected section of a miniature structure.7. The system of claim 5 further comprisinga branch bus bar having a pair of elongated bus bar strips having a geometrical dimension across the width thereof which is substantially equal to said selected geometrical dimension, a conductive metal foil top layer and an adhesive bottom layer, said branch bus bar strips being positioned in a spaced parallel relationship wherein the spacing between the parallel center lines thereof is substantially equal to said predetermined distance, said branch bus bar strips each having one end thereof folded back upon itself with the adhesive layer of the folded end in contact with and adhering to the adhesive layer of the unfolded bus bar strip to form a coplanar mating contact with the conductive metal foil layer being located on the outer surface of the folded end, one of said mating contacts at the end of each bus bar strip being positioned in mating electrical contact with the conductive metal foil top layer of the main bus bar; anda second removable bi-prong electrical fastening device formed of a pair of spaced conductive fastening members electrically connected to an output terminal, each of said spaced conductive fastening members being electrically connected to a separate output terminal and each of which terminate in an elongated tapered cutting edge, said tapered cutting edges being in spaced parallel relationship and having a dimension therebetween substantially equal to said predetermined distance and which, when urged into fastening engagement with a said miniature structure, are adapted to pierce, form an elongated slit in and parallel to the center line of each branch bus bar strip and be driven through the elongated strips of the branch bus bar forming an electrical connection therewith and into fastening engagement with a section of a said miniature structure located under the adhesive layer, and being adapted to terminate said electrical connection from each of the branch bus bar strips upon removal of the second fastening device conductive fastening member from fastening engagement with said selected portion of a miniature structure by slideably withdrawing the tapered edges from each branch bus bar strip leaving a slight elongated slit therein while enabling the strip to maintain a voltage potential thereacross independent of the elongated slit.8. The system of claim 7 further comprisinga third bi-prong electrical fastening device identical to said second bi-prong electrical fastening device and adapted to pierce and be driven through the branch bus bar forming an electrical connection therewith and into fastening engagement with a selected section of a said miniature structure.9. The system of claim 3 further comprisinga pair of insulated electrical conductors wherein each conductor has one end thereof electrically attached to an output terminal and the other end of the conductor terminating with the conductive end section thereof exposed; anda light bulb capable of being illuminated by the low voltage signal, said light bulb having a pair of conducting leads extending therefrom with each end thereof electrically connected to one of the exposed conductor end sections forming an electrical circuit therewith.10. The system of claim 9 further comprisinga heat-shrinkable cylinder positioned around each joined connection of the conducting lead and electrical conductor, said cylinder having an axial length sufficient to encapsulate and form a tight insulating fitting around said electrical connection.11. A low voltage distribution system for wiring a miniature structure for electricity comprisinga step down voltage transformer adapted to be electrically connected to an alternating current voltage source having a voltage level higher than the desired distribution voltage level for producing a low voltage signal at the level desired for the distribution voltage;a first and second elongated bus bar strip, each having a selected geometrical dimension across the width thereof and formed of a conductive metal foil top layer and a bottom adhesive layer, said bus bar strips being affixed to a selected section of a said miniature structure and positioned in a spaced parallel relationship with apredetermined distance between the center lines of each strip being at least equal to said selected geometrical dimension;a pair of electrical connectors extending from the transformer to the bus bar strips for applying the low voltage signal across said bus bar strips having a plurality of bi-prong removable electrical fastening members terminating in a pair of spaced parallel elongated tapered cutting edges having a dimension therebetween substantially equal to said predetermined distance and which, when urged into fastening engagement with said miniature structure, is adapted to pierce, form an elongated slit in and parallel to the center line of each bus bar and be driven into and through the bus bar strips forming a plurality of parallel electrical connections therewith and into fastening engagement with a different selected section of a said miniature structure, each of which are located opposite the fastening member and under the bus bar strips and which is adapted to terminate said electrical connection with each of the bus bar strips upon removal of the fastening member from fastening engagement with said selected portion of a miniature structure by slideably withdrawing from each bus bar strip leaving a slight elongated slit therein while enabling the strips to maintain a voltage potential thereacross independent of the elongated slit; anda plurality of light bulbs each of which has a pair of conducting leads which are electrically connected across one of said bi-prong electrical fastening members, said light bulbs each being in parallel circuit connection to each other and being responsive to the low voltage signal applied across the bus bar to become illuminated.12. The system of claim 11 wherein the bi-prong electrical fastening member has a round cross-section.13. The system of claim 12 wherein the bi-prong electrical fastening member has a rectangular cross-section.14. A miniature structure low voltage distribution system having a main bus bar formed of a conductive metal foil layer which is affixed to the miniature structure by an adhesive bottom layer, said main bus bar having a pair of spaced parallel elongated bus bar strips each having a selected geometrical dimension across the width thereof and with the spacing between the center lines of the parallel strips being a predetermined distance, said distribution system comprisingat least one bi-prong removable electrical fastening device formed of a pair of spaced conductive fastening members each of which are electrically connected to an output terminal, each of said fastening members terminating in an elongated tapered cutting edge, said tapered cutting edges being in spaced parallel relationship and having a dimension therebetween substantially equal to said predetermined distance, and which, when urged into fastening engagement with a said miniature structure, are adapted to pierce, form an elongated slit in and parallel to the center line of each bus bar and be driven through each of the bus bar strips of the main bus bar forming an electrical connection therewith and into fastening engagement with said selected portion of a said miniature structure located under the adhesive layer, and being adapted to terminate said electrical connection with each of the bus bar strips upon removal of the fastening member from fastening engagement with said selected portion of aminiature structure by slideably withdrawing the tapered edges from each bus bar strip leaving a slight elongated slit therein while enabling the strips to maintain a voltage potential thereacross independent of the elongated slit.微型结构低压分配系统1.发明背景此项发明涉及到一项独特的低压分配系统，此系统为一个有着电子线路的微型结构，它包含着电力加速构件，其中的电子连接器使一个电灯泡安插在这个微型结构中。

电气自动化外文翻译外文文献英文文献

外文出处：Farhadi, A. (2008). Modeling, simulation, and reduction of conducted electromagnetic interference due to a pwm buck type switching power supply. Harmonics and Quality of Power, 2008. ICHQP 2008. 13th International Conference on, 1 - 6.Modeling, Simulation, and Reduction of Conducted Electromagnetic Interference Due to a PWM Buck Type Switching Power Supply IA. FarhadiAbstract:Undesired generation of radiated or conducted energy in electrical systems is called Electromagnetic Interference (EMI). High speed switching frequency in power electronics converters especially in switching power supplies improves efficiency but leads to EMI. Different kind of conducted interference, EMI regulations and conducted EMI measurement are introduced in this paper. Compliancy with national or international regulation is called Electromagnetic Compatibility (EMC). Power electronic systems producers must regard EMC. Modeling and simulation is the first step of EMC evaluation. EMI simulation results due to a PWM Buck type switching power supply are presented in this paper. To improve EMC, some techniques are introduced and their effectiveness proved by simulation.Index Terms:Conducted, EMC, EMI, LISN, Switching SupplyI. INTRODUCTIONFAST semiconductors make it possible to have high speed and high frequency switching in power electronics []1. High speed switching causes weight and volume reduction of equipment, but some unwanted effects such as radio frequency interference appeared []2. Compliance with electromagnetic compatibility (EMC) regulations is necessary for producers to present their products to the markets. It is important to take EMC aspects already in design phase []3. Modeling and simulation is the most effective tool to analyze EMC consideration before developing the products. A lot of the previous studies concerned the low frequency analysis of power electronics components []4[]5. Different types of power electronics converters are capable to be considered as source of EMI. They could propagate the EMI in both radiated and conducted forms. Line Impedance Stabilization Network (LISN) is required for measurement and calculation of conducted interference level []6. Interference spectrum at the output of LISN is introduced as the EMC evaluation criterion []7[]8. National or international regulations are the references forthe evaluation of equipment in point of view of EMC []7[]8.II. SOURCE, PATH AND VICTIM OF EMIUndesired voltage or current is called interference and their cause is called interference source. In this paper a high-speed switching power supply is the source of interference.Interference propagated by radiation in area around of an interference source or by conduction through common cabling or wiring connections. In this study conducted emission is considered only. Equipment such as computers, receivers, amplifiers, industrial controllers, etc that are exposed to interference corruption are called victims. The common connections of elements, source lines and cabling provide paths for conducted noise or interference. Electromagnetic conducted interference has two components as differential mode and common mode []9.A. Differential mode conducted interferenceThis mode is related to the noise that is imposed between different lines of a test circuit by a noise source. Related current path is shown in Fig. 1 []9. The interference source, path impedances, differential mode current and load impedance are also shown in Fig. 1.B. Common mode conducted interferenceCommon mode noise or interference could appear and impose between the lines, cables or connections and common ground. Any leakage current between load and common ground couldbe modeled by interference voltage source.Fig. 2 demonstrates the common mode interference source, common mode currents Iandcm1 and the related current paths[]9.The power electronics converters perform as noise source Icm2between lines of the supply network. In this study differential mode of conducted interference is particularly important and discussion will be continued considering this mode only.III. ELECTROMAGNETIC COMPATIBILITY REGULATIONS Application of electrical equipment especially static power electronic converters in different equipment is increasing more and more. As mentioned before, power electronics converters are considered as an important source of electromagnetic interference and have corrupting effects on the electric networks []2. High level of pollution resulting from various disturbances reduces the quality of power in electric networks. On the other side some residential, commercial and especially medical consumers are so sensitive to power system disturbances including voltage and frequency variations. The best solution to reduce corruption and improve power quality is complying national or international EMC regulations. CISPR, IEC, FCC and VDE are among the most famous organizations from Europe, USA and Germany who are responsible for determining and publishing the most important EMC regulations. IEC and VDE requirement and limitations on conducted emission are shown in Fig. 3 and Fig. 4 []7[]9.For different groups of consumers different classes of regulations could be complied. Class Afor common consumers and class B with more hard limitations for special consumers are separated in Fig. 3 and Fig. 4. Frequency range of limitation is different for IEC and VDE that are 150 kHz up to 30 MHz and 10 kHz up to 30 MHz respectively. Compliance of regulations is evaluated by comparison of measured or calculated conducted interference level in the mentioned frequency range with the stated requirements in regulations. In united European community compliance of regulation is mandatory and products must have certified label to show covering of requirements []8.IV. ELECTROMAGNETIC CONDUCTED INTERFERENCE MEASUREMENTA. Line Impedance Stabilization Network (LISN)1-Providing a low impedance path to transfer power from source to power electronics converter and load.2-Providing a low impedance path from interference source, here power electronics converter, to measurement port.Variation of LISN impedance versus frequency with the mentioned topology is presented inFig. 7. LISN has stabilized impedance in the range of conducted EMI measurement []7.Variation of level of signal at the output of LISN versus frequency is the spectrum of interference. The electromagnetic compatibility of a system can be evaluated by comparison of its interference spectrum with the standard limitations. The level of signal at the output of LISN in frequency range 10 kHz up to 30 MHz or 150 kHz up to 30 MHz is criterion of compatibility and should be under the standard limitations. In practical situations, the LISN output is connected to a spectrum analyzer and interference measurement is carried out. But for modeling and simulation purposes, the LISN output spectrum is calculated using appropriate software.基于压降型PWM开关电源的建模、仿真和减少传导性电磁干扰摘要：电子设备之中杂乱的辐射或者能量叫做电磁干扰(EMI)。

电气工程的外文文献(及翻译)

电气工程的外文文献(及翻译)文献一：Electric power consumption prediction model based on grey theory optimized by genetic algorithms本文介绍了一种基于混合灰色理论与遗传算法优化的电力消耗预测模型。

该模型使用时间序列数据来建立模型，并使用灰色理论来解决数据的不确定性问题。

通过遗传算法的优化，模型能够更好地预测电力消耗，并取得了优异的预测结果。

此模型可以在大规模电力网络中使用，并具有较高的可行性和可靠性。

文献二：Intelligent control for energy-efficient operation of electric motors本文研究了一种智能控制方法，用于电动机的节能运行。

该方法提供了一种更高效的控制策略，使电动机能够在不同负载条件下以较低的功率运行。

该智能控制使用模糊逻辑方法来确定最佳的控制参数，并使用遗传算法来优化参数。

实验结果表明，该智能控制方法可以显著降低电动机的能耗，节省电能。

文献三：Fault diagnosis system for power transformers based on dissolved gas analysis本文介绍了一种基于溶解气体分析的电力变压器故障诊断系统。

通过对变压器油中的气体样品进行分析，可以检测和诊断变压器内部存在的故障类型。

该系统使用人工神经网络模型来对气体分析数据进行处理和分类。

实验结果表明，该系统可以准确地检测和诊断变压器的故障，并有助于实现有效的维护和管理。

文献四：Power quality improvement using series active filter based on iterative learning control technique本文研究了一种基于迭代研究控制技术的串联有源滤波器用于电能质量改善的方法。

电气工程及其自动化专业英语翻译

翻译翻译Electric Power Systems.The modern society depends on the electricity supply more heavily than ever before. It can not be imagined what the world should be if the electricity supply were interrupted all over the world. Electric power systems (or electric energy systems), providing electricity to the modern society, have become indispensable components of the industrial world. The first complete electric power system (comprising a generator, cable, fuse, meter, and loads) was built by Thomas Edison – the historic Pearl Street Station in New York City which began operation in September 1882. This was a DC system consisting of a steam-engine-driven DC generator supplying power to 59 customers within an area roughly 1.5 km in radius. The load, which consisted entirely of incandescent lamps, was supplied at 110 V through an underground cable system.. Within a few years similar systems were in operation in most large cities throughout the world. With the development of motors by Frank Sprague in 1884, motor loads were added to such systems. This was the beginning of what would develop into one of the largest industries in the world. In spite of the initial widespread use of DC systems, they were almost completely superseded by AC systems. By 1886, the limitations of DC systems were becoming increasingly apparent. They could deliver power only a short distance from generators. To keep transmission power losses ( I 2 R ) and voltage drops to acceptable levels, voltage levels had to be high for long-distance power transmission. Such high voltages were not acceptable for generation and consumption of power; therefore, a convenient means for voltage transformation became a necessity.The development of the transformer and AC transmission by L. Gaulard and JD Gibbs of Paris, France, led to AC electric power systems. In 1889, the first AC transmission line in North America was put into operation in Oregon between Willamette Falls and Portland. It was a single-phase line transmitting power at 4,000 V over a distance of 21 km. With the development of polyphase systems by Nikola Tesla, the AC system became even more attractive. By 1888, Tesla held several patents on AC motors, generators, transformers, and transmission systems. Westinghouse bought the patents to these early inventions, and they formed the basis of the present-day AC systems. In the 1890s, there was considerable controversy over whether the electric utility industry should be standardized on DC or AC. By the turn of the century, the AC system had won out over the DC system for the following reasons: （1）Voltage levels can be easily transformed in AC systems, thus providing the flexibility for use of different voltages for generation, transmission, and consumption.（2）AC generators are much simpler than DC generators.（3）AC motors are much simpler and cheaper than DC motors.The first three-phase line in North America went into operation in 1893——a 2,300 V, 12 km line in southern California. In the early period of AC power transmission, frequency was not standardized. This poses a problem for interconnection. Eventually 60 Hz was adopted as standard in North America, although 50 Hz was used in many other countries. The increasing need for transmitting large amounts of power over longer distance created an incentive to use progressively high voltage levels. To avoid the proliferation of an unlimited number of voltages, the industry has standardized voltage levels. In USA, the standards are 115, 138, 161, and 230 kV for the high voltage (HV) class, and 345, 500 and 765 kV for the extra-high voltage (EHV) class. In China, the voltage levels in use are 10, 35, 110 for HV class, and 220, 330 (only in Northwest China) and 500 kV for EHV class . The first 750 kVtransmission line will be built in the near future in Northwest China. With the development of the AC/DC converting equipment, high voltage DC (HVDC) transmission systems have become more attractive and economical in special situations. The HVDC transmission can be used for transmission of large blocks of power over long distance, and providing an asynchronous link between systems where AC interconnection would be impractical because of system stability consideration or because nominal frequencies of the systems are different. The basic requirement to a power system is to provide an uninterrupted energy supply to customers with acceptable voltages and frequency. Because electricity can not be massively stored under a simple and economic way, the production and consumption of electricity must be done simultaneously. A fault or misoperation in any stages of a power system may possibly result in interruption of electricity supply to the customers. Therefore, a normal continuous operation of the power system to provide a reliable power supply to the customers is of paramount importance. Power system stability may be broadly defined as the property of a power system that enables it to remain in a state of operating equilibrium under normal operating conditions and to regain an acceptable state of equilibrium after being subjected to a disturbance.. Instability in a power system may be manifested in many different ways depending on the system configuration and operating mode. Traditionally, the stability problem has been one of maintaining synchronous operation. Since power systems rely on synchronous machines for generation of electrical power, a necessary condition for satisfactory system operation is that all synchronous machines remain in synchronism or, colloquially "in step". This aspect of stability is influenced by the dynamics of generator rotor angles and power-angle relationships, and then referred to " rotor angle stability "译文：电力系统现代社会比以往任何时候更多地依赖于电力供应。

电气工程及其自动化专业毕业论文外文翻译

本科毕业设计(论文)中英文对照翻译院(系部）工程学院专业名称电气工程及其自动化年级班级 11级2班学生姓名蔡李良指导老师赵波Infrared Remote Control SystemAbstractRed outside data correspondence the technique be currently within the scope of world drive extensive usage of a kind of wireless conjunction technique, drive numerous hardware and software platform support。

Red outside the transceiver product have cost low，small scaled turn, the baud rate be quick，point to point SSL, be free from electromagnetism thousand Raos etc. characteristics，can realization information at dissimilarity of the product fast，convenience，safely exchange and transmission, at short distance wireless deliver aspect to own very obvious of advantage。

Along with red outside the data deliver a technique more and more mature, the cost descend, red outside the transceiver necessarily will get at the short distance communication realm more extensive of application.The purpose that design this s ystem is transmit customer’s operation information with infrared rays for transmit media, then demodulate original signal with receive circuit。

毕业设计毕业论文电气工程及其自动化外文翻译中英文对照

毕业设计毕业论文电气工程及其自动化外文翻译中英文对照电气工程及其自动化外文翻译中英文对照一、引言电气工程及其自动化是一门涉及电力系统、电子技术、自动控制和信息技术等领域的综合学科。

本文将翻译一篇关于电气工程及其自动化的外文文献，并提供中英文对照。

二、文献翻译原文标题：Electric Engineering and Its Automation作者：John Smith出版日期：2020年摘要：本文介绍了电气工程及其自动化的基本概念和发展趋势。

首先，介绍了电气工程的定义和范围。

其次，探讨了电气工程在能源领域的应用，包括电力系统的设计和运行。

然后，介绍了电气工程在电子技术领域的重要性，包括电子设备的设计和制造。

最后，讨论了电气工程与自动控制和信息技术的结合，以及其在工业自动化和智能化领域的应用。

1. 介绍电气工程是一门研究电力系统和电子技术的学科，涉及发电、输电、配电和用电等方面。

电气工程的发展与电力工业的发展密切相关。

随着电力需求的增长和电子技术的进步，电气工程的重要性日益凸显。

2. 电气工程在能源领域的应用电气工程在能源领域的应用主要包括电力系统的设计和运行。

电力系统是由发电厂、输电线路、变电站和配电网络等组成的。

电气工程师负责设计和维护这些设施，以确保电力的可靠供应。

3. 电气工程在电子技术领域的重要性电气工程在电子技术领域的重要性体现在电子设备的设计和制造上。

电子设备包括电脑、手机、电视等消费电子产品，以及工业自动化设备等。

电气工程师需要掌握电子电路设计和数字信号处理等技术，以开发出高性能的电子设备。

4. 电气工程与自动控制和信息技术的结合电气工程与自动控制和信息技术的结合是电气工程及其自动化的核心内容。

自动控制技术可以应用于电力系统的运行和电子设备的控制，以提高系统的稳定性和效率。

信息技术则可以用于数据采集、处理和传输，实现对电力系统和电子设备的远程监控和管理。

5. 电气工程在工业自动化和智能化领域的应用电气工程在工业自动化和智能化领域的应用越来越广泛。

3-电气工程及其自动化专业外文文献英文文献外文翻译

3-电气工程及其自动化专业外文文献英文文献外文翻译1、外文原文(复印件)A: Fundamentals of Single-chip MicrocomputerThe single-chip microcomputer is the culmination of both the development of the digital computer and the integrated circuit arguably the tow most significant inventions of the 20th century [1].These tow types of architecture are found in single-chip microcomputer. Some employ the split program/data memory of the Harvard architecture, shown in Fig.3-5A-1, others follow the philosophy, widely adapted for general-purpose computers and microprocessors, of making no logical distinction between program and data memory as in the Princeton architecture, shown in Fig.3-5A-2.In general terms a single-chip microcomputer is characterized by the incorporation of all the units of a computer into a single device, as shown in Fig3-5A-3.ProgramInput& memoryOutputCPU unitDatamemoryFig.3-5A-1 A Harvard typeInput&Output CPU memoryunitFig.3-5A-2. A conventional Princeton computerExternal Timer/ System Timing Counter clock componentsSerial I/OReset ROMPrarallelI/OInterrupts RAMCPUPowerFig3-5A-3. Principal features of a microcomputerRead only memory (ROM).ROM is usually for the permanent,non-volatile storage of an applications program .Many microcomputers and microcontrollers are intended for high-volume applications and hence the economical manufacture of the devices requires that the contents of the program memory be committed permanently during the manufacture of chips . Clearly, this implies a rigorous approach to ROM code development since changes cannot be made after manufacture .This development process may involve emulation using a sophisticated development system with a hardware emulation capability as well as the use of powerful software tools.Some manufacturers provide additional ROM options by including in their range devices with (or intended for use with) user programmablememory. The simplest of these is usually device which can operate in a microprocessor mode by using some of the input/output lines as an address and data bus for accessing external memory. This type of device can behave functionally as the single chip microcomputer from which itis derived albeit with restricted I/O and a modified external circuit. The use of these ROMlessdevices is common even in production circuits where the volume does not justify the development costs of custom on-chip ROM[2];there canstill be a significant saving in I/O and other chips compared to a conventional microprocessor based circuit. More exact replacement for ROM devices can be obtained in the form of variants with 'piggy-back' EPROM(Erasable programmable ROM )sockets or devices with EPROM instead of ROM 。

电气工程及其自动化外文翻译外文文献英文文献短路电流

电气工程及其自动化外文翻译外文文献英文文献短路电流Short-circuit current1 Terms and DefinitionsThe following terms and definitions correspond largely to those defined in IEC 60909. Refer to this standard for all terms not used in this book.The terms short circuit and ground fault describe faults in the isolation ofoperational equipment which occur when live parts are shunted out asa result. , Causes:1. Overtemperatures due to excessively high overcurrents.2. Disruptive discharges due to overvoltages.3. Arcing due to moisture together with impure air, especially on insulators. , Effects:1. Interruption of power supply.2. Destruction of system components.3. Development of unacceptable mechanical and thermal stresses in electrical operational equipment., Short circuit:According to IEC 60 909, a short circuit is the accidental or intentional conductive connection through a relatively low resistance orimpedance between two or more points of a circuit which are normally at different potentials., Short circuit current:According to IEC 60 909, a short circuit current results from a short circuit in an electrical network.It is necessary to differentiate here between the short circuit current at the position of the short circuit and the transferred short circuit currents in the network branches., Initial symmetrical short circuit current:This is the effective value of the symmetrical short circuit current at the moment at which the short circuit arises, when the short circuit impedance has its value from the time zero., Initial symmetrical short circuit apparent power:The short circuit power represents a fictitious parameter. During the planning of networks, the short circuit power is a suitable characteristic number. , Peak short circuit current:The largest possible momentary value of the short circuit occurring. , Steady state short circuit current:Effective value of the initial symmetrical short circuit current remaining after the decay of all transient phenomena., DC aperiodic component:Average value of the upper and lower envelope curve of the short circuit current, which slowly decays to zero., Symmetrical breaking current:Effective value of the short circuit current which flows through the contact switch at the time of the first contact separation., Equivalent voltage source:The voltage at the position of the short circuit, which is transferred to the positive-sequence system as the only effective voltage and is used for the calculation of the short circuit currents., Superposition method:The superposition method considers the previous load of the network before the occurrence of the short circuit. It is necessary to know the load flow and the setting of the transformer step switch., Voltage factor:Ratio between the equivalent voltage source and the network voltage Un,divided by 3., Equivalent electrical circuit:Model for the description of the network by an equivalent circuit. , Far-from-generator short circuit:The value of the symmetrical AC periodic component remains essentially constant., Near-to-generator short circuit:The value of the symmetrical AC periodic component does not remain constant. The synchronous machine first delivers an initial symmetrical short circuit current which is larger than twice the rated current of the synchronous machine. , Positive-sequence short circuit impedance:The impedance of the positive-sequence system as seen from the position of theshort circuit., Negative-sequence short circuit impedance:The impedance of the negative-sequence system as seen from the position ofthe short circuit., Zero-sequence short circuit impedanceThe impedance of the zero-sequence system as seen from the position of theshort circuit. Three times the value of the neutral point to ground impedanceoccurs here., Short circuit impedance:Impedance required for calculation of the short circuit currents at the positionof the short circuit. p•••1.2 Short circuit path in the positive-sequence systemFor the same external conductor voltages, a three-pole short circuit allows three currents of the same magnitude to develop between the three conductors. It is therefor only necessary to consider one conductor in further calculations. Depending on the distance from the position of the short circuit from the generator, here it is necessary to consider near-to-generator andfar-from-generator short circuits separately. For far-from-generator and near-to-generator short circuits, the short circuit path can be represented by a mesh diagram with AC voltage source, reactances X and resistances R (Figure 1.2). Here, X and R replace all components such as cables,conductors, transformers, generators and motors.Fig. 1.2: Equivalent circuit of the short circuit current path in the positive-sequence systemThe following differential equation can be used to describe theshort circuit processwhere w is the phase angle at the point in time of the short circuit. This assume that the current before S closes (short circuit) is zero. The inhomogeneous first order differential equation can be solved by determining the homogeneous solution ik and a particular solution i?k.The homogeneous solution, with the time constant g = L/R, solution yields:For the particular solution, we obtain:The total short circuit current is composed of both components:The phase angle of the short circuit current (short circuit angle)is then, in accordance with the above equation,For the far-from-generator short circuit, the short circuit current is therefore made up of a constant AC periodic component and the decaying DC aperiodic component. From the simplified calculations, we can now reach the following conclusions:, The short circuit current always has a decaying DC aperiodic component inaddition to the stationary AC periodic component., The magnitude of the short circuit current depends on theoperating angle ofthe current. It reaches a maximum at c = 90 (purely inductive load). Thiscase serves as the basis for further calculations., .The short circuit current is always inductive.1.4 Methods of short circuit calculationThe equivalent voltage source will be introduced here as the only effective voltage of the generators or network inputs for thecalculation of short circuit currents. The internal voltages of generators or network inputs are short circuited, and at the position ofthe short circuit (fault position) the value ( is used as the only effective voltage (Figure 1.4)., The voltage factor c [5] considers (Table 1.1):, The different voltage values, depending on time and position, The step changes of the transformer switch, That the loads and capacitances in the calculation of the equivalentvoltage source can be neglected, The subtransient behavior of generators and motors, This method assumes the following conditions:, The passive loads and conductor capacitances can be neglected , The step setting of the transformers do not have to be considered , The excitation of the generators do not have to be considered , The time and position dependence of the previous load (loading state) ofthe network does not have to be consideredFig. 1.4: Network circuit with equivalent voltage sourcea) three-phase network, b) equivalent circuit in positive sequencesystem1.4.2 Superposition methodThe superposition method is an exact method for the calculation of the short circuit currents. The method consists of three steps. The voltage ratios and the loading condition of the network must be known before the occurrence of the short circuit. In the first step the currents, voltages and the internal voltages for steady-state operation before onset of the short circuit are calculated (Figure 1.5b). The calculation considers the impedances, power supply feeders and node loads of the active elements. In the second step the voltage applied to the fault location before the occurrence of the short circuit and the current distribution at the fault location are determined with a negative sign (Figure 1.5c). This voltage source is the only voltage source in the network. The internal voltages are short-circuited. In the third step both conditions are superimposed. We then obtain zero voltage at the fault location. The superposition of the currents also leads to the value zero. The disadvantage of this method is that the steady-state condition must be specified. The data for the network (effective andreactive power, node voltages and the step settings of the transformers) are often difficult to determine. The question also arises, which operating state leads to the greatest short circuit current. Figure 1.5 illustrates the procedure for the superposition method.Fig. 1.5: Principle of the superposition methoda) undisturbed operation, b) operating voltage at the faultlocation, c) superposition of a) and b)1.4.3 Transient calculationWith the transient method the individual operating equipment and, as a result, the entire network are represented by a system of differential equations. The calculation is very tedious. The method with the equivalent voltage source is a simplification relative to the other methods. Since 1988, it has been standardized internationally in IEC 60 909. The calculation is independent of a current operational state. Inthisbook, we will therefore deal with and discuss the method with the equivalent voltage source.1.5 Calculating with reference variablesThere are several methods for performing short circuit calculations with absolute and reference impedance values. A few are summarized here and examples are calculated for comparison. To define the relative values, there are two possible reference variables.For the characterization of electrotechnical relationships we require the four parameters:, Voltage U in V, Current I in A, Impedance Z in W, Apparent power S in VA.Three methods can be used to calculate the short circuit current:1. The Ohm system: Units: kV, kA, V, MVA2.The pu system:This method is used predominantly for electrical machines; allfour parameters u, i, z and s are given as per unit (unit = 1). The reference valueis 100 MVA. The two reference variables for this system are UB and SB.Example: The reactances of a synchronous machine Xd, X?d, X?d are givenin pu or in % pu, multiplied by 100 %.3.The %/MVA system:This system is especially well suited for thefastdetermination of short circuit impedances. As formal unit only the % symbol isadd.短路电流1 术语和定义以下术语和定义对应IEC 标准60 909。

毕业设计毕业论文电气工程及其自动化外文翻译中英文对照

理工大学毕业设计（外文翻译材料）学院：专业：学生姓名：指导教师：电气与电子工程学院电气工程及其自动化- .专业文档.Relay protection development present situationAbstract: Reviewed our country electrical power system relay protection technological development process, has outlined the microcomputer relay protection technology achievement, propose the future relay protection technological development tendency will be: Computerizes, networked, protects, the control, the survey, the data communication integration and the artificial intellectualization.Key word: relay protection, present situation development, future development1 relay protection development present situationThe electrical power system rapid development to the relay protection propose unceasingly the new request, the electronic technology, computer technology and the communication rapid development unceasingly has poured into the new vigor for the relay protection technology development, therefore, the relay protection technology is advantageous, has completed the development 4 historical stage in more than 40 years time.After the founding of the nation, our country relay protection discipline, the relay protection design, the relay manufacture industry and the relay protection technical team grows out of nothing, has passed through the path in about 10 years which advanced countries half century passes through. The 50's, our country engineers and technicians creatively absorption, the digestion, have grasped the overseas advanced relay protection equipment performance and the movement technology , completed to have the deep relay protection theory attainments and the rich movement experience relay protection technical team, and grew the instruction function to the national relay protection technical team's establishment. The relay factory introduction has digested at that time the overseas advanced relay manufacture technology, has established our country relay manufacturing- .专业文档.industry. Thus our country has completed the relay protection research, the design, the manufacture, the movement and the teaching complete system in the 60's. This is a time which the mechanical and electrical relay protection prospers, was our countries relay protection technology development has laid the solid foundation.From the end of the 50's, the transistor relay protection was starting to study. In the 60's to the 80's，it is the times which the transistor relay protection vigorous development and widely used. Tianjin University and the Nanjing electric power automation plant cooperation research 500kV transistor direction high frequency protection the transistor high frequency block system which develops with the Nanjing electric power automation research institute is away from the protection, moves on the Gezhou Dam 500kV line , finished the 500kV line protection to depend upon completely from the overseas import time.From the 70's, start based on the integration operational amplifier integrated circuit protection to study. Has formed the completely series to at the end of 80's integrated circuit protection, substitutes for the transistor protection gradually. The development, the production, the application the integrated circuit protects which to the beginning of the 90's still were in the dominant position, this was the integrated circuit protection time. The integrated electricity road work frequency conversion quantity direction develops which in this aspect Nanjing electric power automation research institute high frequency protected the vital role, the Tianjin University and the Nanjing electric power automation plant cooperation development integrated circuit phase voltage compensated the type direction high frequency protection also moves in multi- strip 220kV and on the 500kV line.Our country namely started the computer relay protection research from the end of the 70's, the institutions of higher learning and the scientific research courtyard institute forerunner's function. Huazhong University of- .专业文档.Science and Technology, southeast the university, the North China electric power institute, the Xian Jiao tong University, the Tianjin University, Shanghai Jiao tong University, the Chongqing University and the Nanjing electric power automation research institute one after another has all developed the different principle, the different pattern microcomputer protective device. In 1984 the original North China electric power institute developed the transmission line microcomputer protective device first through the evaluation and in the system the find application, had opened in our country relay protection history the new page, protect the promotion for the microcomputer to pave the way. In the host equipment protection aspect, the generator which southeast the university and Huazhong University of Science and Technology develop loses magnetism protection, the generator protection and the generator? Bank of transformers protection also one after another in 1989、1994 through appraisal and investment movement. The Nanjing electric power automation research institute develops microcomputer line protective device also in 1991 through appraisal. The Tianjin University and the Nanjing electric power automation plant cooperation development microcomputer phase voltage compensated the type direction high frequency protection, the Xian Jiao tong University and the Xuchang Relay Factory cooperation development positive sequence breakdown component direction high frequency protection also one after another in 1993, in 1996 through the appraisal. Here, the different principle, the different type microcomputer line and the host equipment protect unique, provided one batch of new generation of performance for the electrical power system fine, the function has been complete, the work reliable relay protection installment. Along with the microcomputer protective device research, in microcomputer aspect and so on protection software, algorithm has also yielded the very many theories result. May say- .专业文档.started our country relay protection technology from the 90's to enter the time which the microcomputer protected.2 relay protections future developmentThe relay protection technology future the tendency will be to computerizes, networked, the intellectualization, will protect, the control, the survey and the data communication integration development.2.1 computerizesAlong with the computer hardware swift and violent development, the microcomputer protection hardware also unceasingly is developing. The original North China electric power institute develops the microcomputer line protection hardware has experienced 3 development phases: Is published from 8 lists CPU structure microcomputer protection, does not develop to 5 years time to the multi- CPU structure, latter developed to the main line does not leave the module the big modular structure, the performance enhances greatly, obtained the widespread application. Huazhong University of Science and Technology develops the microcomputer protection also is from 8 CPU, develops to take the labor controlling machine core partially as the foundation 32 microcomputers protection.The Nanjing electric power automation research institute from the very beginning has developed 16 CPU is the foundation microcomputer line protection, obtained the big area promotion, at present also is studying 32 protections hardware system. Southeast the university develops the microcomputer host equipment protects the hardware also passed through improved and the enhancement many times. The Tianjin University from the very beginning is the development take more than 16 CPU as the foundation microcomputer line protection, in 1988 namely started to study take 32 digital signals processor (DSP) as the foundation protection, the control, the survey integration microcomputer installment, at present cooperated with- .专业文档.the Zhuhai automatic equipment company develops one kind of function complete 32 big modules, a module was a minicomputer. Uses 32 microcomputers chips only to focus by no means on the precision, because of the precision the a/d switch resolution limit, is surpassed time 16 all is accepts with difficulty in the conversion rate and the cost aspect; 32 microcomputers chips have the very high integration rate more importantly, very high operating frequency and computation speed, very big addressing space, rich command system and many inputs outlet. The CPU register, the data bus, the address bus all are 32, has the memory management function, the memory protection function and the duty transformation function, and (cache) and the floating number part all integrates the high speed buffer in CPU.The electrical power system the request which protects to the microcomputer enhances unceasingly, besides protection basic function, but also should have the large capacity breakdown information and the data long-term storage space, the fast data processing function, the formidable traffic capacity, with other protections, the control device and dispatches the networking by to share the entire system data, the information and the network resources ability, the higher order language programming and so on. This requests the microcomputer protective device to have is equal to a pc machine function. In the computer protection development initial period, once conceived has made the relay protection installment with a minicomputer. At that time because the small machine volume big, the cost high, the reliability was bad, this tentative plan was not realistic. Now, with the microcomputer protective device size similar labor controlling machine function, the speed, the storage capacity greatly has surpassed the same year small machine, therefore, made the relay protection with complete set labor controlling machine the opportunity already to be mature, this will be one of development directions which the microcomputer protected. The- .专业文档.Tianjin University has developed the relay protection installment which Cheng Yong tong microcomputer protective device structure quite same not less than one kind of labor controlling machine performs to change artificially becomes. This kind of equipment merit includes: has the 486pc machine complete function, can satisfy each kind of function request which will protect to current and the future microcomputer. size and structure and present microcomputer protective device similar, the craft excellent, quakeproof, guards against has been hot, guards against electromagnetic interference ability, may move in the very severe working conditions, the cost may accept. Uses the STD main line or the pc main line, the hardware modulation, may select the different module willfully regarding the different protection, the disposition nimble, and is easy to expand.Relay protection installment, computerizes is the irreversible development tendency. How but to satisfies the electrical power system request well, how further enhances the relay protection the reliability, how obtains the bigger economic efficiency and the social efficiency, still must conduct specifically the thorough research.2.2 networkedThe computer network has become the information age as the information and the data communication tool the technical prop, caused the human production and the social life appearance has had the radical change. It profoundly is affecting each industry domain, also has provided the powerful means of communication for each industry domain. So far, besides the differential motion protection and the vertical association protection, all relay protections installment all only can respond the protection installment place electricity spirit. The relay protection function also only is restricted in the excision breakdown part, reduces the accident to affect the scope. This mainly is because lacks the powerful data communication method. Overseas already had proposed the system protection concept, this in mainly referred- .专业文档.to the safe automatic device at that time. Because the relay protection function not only is restricted in the excision breakdown part and the limit accident affects the scope (this is most important task), but also must guarantee the entire system the security stable movement. This requests each protection unit all to be able to share the entire system the movement and the breakdown information data, each protection unit and the superposition brake gear in analyze this information and in the data foundation the synchronized action, guarantees the system the security stable movement. Obviously, realizes this kind of system protection basic condition is joins the entire system each main equipment protective device with the computer network, that is realization microcomputer protective device networked. This under the current engineering factor is completely possible.Regarding the general non- system protection, the realization protective device computer networking also has the very big advantage. The relay protection equipment can obtain system failure information more, then to the breakdown nature, the breakdown position judgment and the breakdown distance examination is more accurate. Passed through the very long time to the auto-adapted protection principle research, also has yielded the certain result, but must realize truly protects to the system movement way and the malfunction auto-adapted, must obtain the more systems movement and the breakdown information, only then realization protection computer networked, can achieve this point.Regarding certain protective device realization computer networking also can enhance the protection the reliability. The Tianjin University in 1993 proposed in view of the future Three Gorges hydroelectric power station 500kv ultrahigh voltage multi-return routes generatrix one kind of distributional generatrix protection principle, developed successfully this kind of equipment initially. Its principle is disperses the traditional central- .专业文档.generatrix protection certain (with to protect generatrix to return way to be same) the generatrix protection unit, the dispersible attire is located in on various return routes protection screen, each protection unit joins with the computer network, each protection unit only inputs this return route the amperage, after transforms it the digital quantity, transmits through the computer network for other all return routes protection unit, each protection unit acts according to this return route the amperage and other all return routes amperage which obtains from the computer network, carries on the generatrix differential motion protection the computation, if the computed result proof is the generatrix interior breakdown then only jumps the book size return route circuit breaker, Breakdown generatrix isolation. When generatrix area breakdown, each protection unit all calculates for exterior breakdown does not act. This kind the distributional generatrix protection principle which realizes with the computer network has the high reliability compared to the traditional central generatrix protection principle. Because if a protection unit receives the disturbance or the miscalculation when moves by mistake, only can wrongly jump the book size return route, cannot create causes the generatrix entire the malignant accident which excises, this regarding looks like the Three Gorges power plant to have the ultrahigh voltage generatrix the system key position to be extremely important.By above may know, microcomputer protective device may enhance the protection performance and the reliability greatly, this is the microcomputer protection development inevitable trend.2.3 protections, control, survey, data communication integrationsIn realization relay protection computerizing with under the condition, the protective device is in fact a high performance, the multi-purpose computer, is in an entire electrical power system computer network intelligent terminal. It may gain the electrical power system movement and- .专业文档.breakdown any information and the data from the net, also may protect the part which obtains it any information and the data transfer for the network control center or no matter what a terminal. Therefore, each microcomputer protective device not only may complete the relay protection function, moreover in does not have in the breakdown normal operation situation also to be possible to complete the survey, the control, the data communication function that is realization protection, control, survey, data communication integration.At present, in order to survey, the protection and the control need, outdoor transformer substation all equipment, like the transformer, the line and so on the secondary voltage, the electric current all must use the control cable to direct to . Lays the massive control cable not only must massively invest, moreover makes the secondary circuit to be extremely complex. But if the above protection, the control, the survey, the data communication integration computer installation, will install in outdoor transformer substation by the protection device nearby, by the protection device voltage, the amperage is changed into after this installment internal circulation the digital quantity, will deliver through the computer network, then might avoid the massive control cable. If takes the network with the optical fiber the transmission medium, but also may avoid the electromagnetic interference. Now the optical current transformer (OTA) and the optical voltage transformer (OTV) in the research trial stage, future inevitably obtained the application in the electrical power system. In uses OTA and in the OTV situation, the protective device should place is apart from OTA and the OTV recent place, that is should place by the protection device nearby. OTA and the OTV light signal inputs after this integration installment in and transforms the electrical signal, on the one hand serves as the protection the computation judgment; On the other hand took the survey quantity, delivers through the network. May to deliver from through the network by the- .专业文档.protection device operation control command this integrated installment, carries out the circuit breaker operation from this the integrated installment. In 1992 the Tianjin University proposed the protection, the control, the survey, the correspondence integration question, and has developed take the tms320c25 digital signal processor (DSP) as a foundation protection, the control, the survey, the data communication integration installment.2.4 intellectualizationsIn recent years, the artificial intelligence technology like nerve network, the genetic algorithms, the evolution plan, the fuzzy logic and so on all obtained the application in electrical power system each domain, also started in the relay protection domain application research. The nerve network is one non-linear mapping method, very many lists the complex non-linear problem with difficulty which the equation or solves with difficulty, the application nerve network side principle may be easily solved. For example exhibits in the situation in the transmission line two sides systems electric potential angle to occur after the transition resistance short-circuits is a non-linear problem, very difficult correctly to make the breakdown position from the protection the distinction, thus creates moves by mistake or resists to move; If thinks after the network method, passes through the massive breakdowns sample training, so long as the sample centralism has fully considered each kind of situation, then in breaks down time any all may correctly distinguish. Other likes genetic algorithms, the evolution plan and so on also all has its unique solution complex question the ability. May cause the solution speed these artificial intelligence method suitable unions to be quicker? The Tianjin University carries on the nerve network type relay protection from 1996 the research, has yielded the preliminary result. May foresee, the artificial intelligence technology must be able to obtain the application in the relay protection domain, by solves the problem which solves with difficulty with the conventional method.- .专业文档.3 conclusionsSince the founding of China's electric power system protection technology has undergone four times. With the rapid development of power systems and computer technology, communications technology, relay technology faces the further development of the trend. Domestic and international trends in the development of protection technologies: computerization, networking, protection, control, measurement, data communications integration and artificial intelligence, which made protection workers difficult task, but also opened up the activities of vast.- .专业文档.继电保护发展现状摘要：回顾我国电力系统继电保护技术的发展过程，概述了微机继电保护技术成果，提出了未来继电保护技术的发展趋势将是：计算机化，网络化，保护，控制，调查，数据通信一体化和人工智能化。

电气工程及其自动化电压波动论文中英文资料外文翻译文献

中英文资料外文翻译文献原文:A SPECIAL PROTECTION SCHEME FOR VOLTAGESTABILITY PREVENTIONAbstractVoltage instability is closely related to the maximum load-ability of a transmission network. The energy flows on the transmission system depend on the network topology, generation and loads, and on the availability of sources that can generate reactive power. One of the methods used for this purpose is the Voltage Instability Predictor (VIP). This relay measures voltages at a substation bus and currents in the circuit connected to the bus. From these measurements, it estimates the Thévenin’s equivalent of the network feeding the substation and the impedance of the load being supplied from the substation. This paper describes an extension to the VIP technique in which measurements from adjoining system buses and anticipated change of load are taken into consideration as well.Keywords: Maximum load ability; Voltage instability; VIP algorithm.1.IntroductionDeregulation has forced electric utilities to make better use of the available transmission facilities of their power system. This has resulted in increased power transfers, reduced transmission margins and diminished voltage security margins.To operate a power system with an adequate security margin, it is essential to estimate the maximum permissible loading of the system using information about the current operation point. The maximum loading of a system is not a fixed quantity but depends on various factors, such as network topology, availability of reactive power reserves and their location etc. Determining the maximum permissible loading, within the voltage stability limit, has become a very important issue in power system operation and planning studies. The conventional P-V or V- Q curves are usually used as a tool for assessing voltage stability and hence for finding the maximum loading at the verge of voltage collapse [1]. These curves are generated by running a large number of load flow cases using, conventional methods. While such procedures can be automated, they are time-consuming and do not readily provide information useful in gaining insight into the cause of stability problems [2].To overcome the above disadvantages several techniques have been proposed in the literature, such as bifurication theory [3], energy method [4], eigen value method [5],multiple load flow solutions method [6] etc.Reference [7] proposed a simple method, which does not require off-line simulation and training. The Voltage Indicator Predictor (VIP) method in [7] is based on local measurements (voltage and current) and produces an estimate of the strength / weakness of the transmission system connected to the bus, and compares it with the local demand. The closer the local demand is to the estimated transmission capacity, the more imminent is the voltage instability. The main disadvantage of this method is in the estimation of the Thévenin’s equivalent, which is obtained from two measurements at different times. For a more exact estimation, one requires two different load measurements.This paper proposes an algorithm to improve the robustness of the VIP algorithm by including additional measurements from surrounding load buses and also taking into consideration local load changes at neighboring buses.2. Proposed MethodologyThe VIP algorithm proposed in this paper uses voltage and current measurements on the load buses and assumes that the impedance of interconnecting lines (12Z ,13Z ) are known, as shown in (Figure 1). The current flowing from the generator bus to the load bus is used to estimate Thévenin’s equivalent for the system in that direction. Similarly the current flowing from other load bus (Figure 2) is used to estimate Thévenin’s equivalent from other direction. This results in following equations (Figure 3). Note that the current coming from the second load bus over the transmission line was kept out of estimation in original (VIP) algorithm.)()()(111112211111----=-+th th th L Z E Z V Z Z V [1] )()()(122112112122----=-+th th th L Z E Z V Z Z V [2] 1111111)()(E th th th I Z V Z E =--- [3] 2122122)()(E th th th I Z V Z E =--- [4] Where 1E I and 2E I are currents coming from Th évenin buses no.1 and 2. Equation (1)-(4) can be combined into a matrix form:⎥⎥⎥⎥⎥⎦⎤⎢⎢⎢⎢⎢⎣⎡---++---++-------------121211111212112121-12111121111211000000th th th th th th L th th L Z Z Z Z Z Z Z Z Z Z Z Z Z Z *=⎥⎥⎥⎥⎦⎤⎢⎢⎢⎢⎣⎡2121th th E E V V ⎥⎥⎥⎥⎦⎤⎢⎢⎢⎢⎣⎡2100E E I I [5] Using the first 2 rows in the system Equations (1)-(4), the voltage on buses number 1 and 2 can be found as shown in Equation (6) below. From Equation (6) wecan see that the voltage is a function of impedances. Note that the method assumes that all Thévenin’s parameters are constant at the time of estimation.⎥⎥⎦⎤⎢⎢⎣⎡⎥⎥⎦⎤⎢⎢⎣⎡++--++=⎥⎦⎤⎢⎣⎡-----------12211111121212112112112111121*th th th th th L th L Z E Z E Z Z Z Z Z Z Z Z V V [6] Where, 111-=L Z y 11212-=Z y and 122-=L Z yThe system equivalent seen from bus no.1 is shown in Figure 3. Figure 4(a) shows the relationship between load admittances (1y and 2y ) and voltage at bus no.1. Power delivered to bus no.1 is (1S ) and it is a function of (1L Z ,2L Z ).1211*L y V S = [7]Equation 7 is plotted in figure 4 (b) as a ‘landscape’ and the maximum loading point depends on where the system trajectory ‘goes over the hill’.Fig. 1. 3-Bus system connections Fig. 2. 1-Bus modelFig. 3. System equivalent as seen by the proposed VIP relay on bus #1 (2-bus model)(a)Voltage Profile (b) Power ProfileFig. 4. Voltage and power profiles for bus #12.1. On-Line Tracking of Thévenin’s ParametersThévenin’s parameters are the main factors that decide the maximum loading of the load bus and hence we can detect the voltage collapse. In Figure3, th E can be expressed by the following equation:I Z V E th load th += [8]V and I are directly available from measurements at the local bus. Equation (8) can be expressed in the matrix form as shown below.⎥⎥⎥⎥⎦⎤⎢⎢⎢⎢⎣⎡--⎥⎥⎥⎥⎦⎤⎢⎢⎢⎢⎣⎡=⎥⎥⎥⎥⎦⎤⎢⎢⎢⎢⎣⎡000010000001)()(00..r i i r th th th th i r I I I I X R i E r E V V [9] B= A X [10] The unknown parameters can be estimated from the following equation:B A AX A T T = [11] Note that all of the above quantities are functions of time and are calculated on a sliding window of discrete data samples of finite, preferably short length. There are additional requirements to make the estimation feasible:• There must be a significant change in load impedance in the data window of at least two set of Measurements.• For small changes in Thévenin’s parameters within a particular data window, the algorithm can estimate properly but if a sudden large change occurs then the process of estimation is postponed until the next data window comes in.• The monitoring device based on the above principle can be used to impose a limit on the loading at each bus, and sheds load when the limit is exceeded. It can also be used to enhance existing voltage controllers. Coordinated control canalso be obtained if communication is available.Once we have the time sequence of voltage and current we can estimate unknowns by using parameter estimation algorithms, such as Ka lm an Filtering approach described [6].stability margin (VSM) due to impedances can be expressed as (Z VSM ); where subscript z denotes the impedance.Therefore we have: Load thev Load Z Z Z Z VSM -= [12] The above equation assumes that both load impedances (1Z , 2Z ) are decreasing at a steady rate, so the power delivered to bus 1 will increase according to Equation(7). However once it reaches the point of collapse power starts to decrease again.Now assume that both loads are functions of time. The maximum critical loading point is then given by Equation(13):011==dtds S Critical [13] Expressing voltage stability margin due to load apparent power as ( S VSM ), we have:Critical Load Critical S SS S VSM -= [14] Note that both Z VSM and S VSM are normalized quantities and their values decrease as the load increases.At the voltage collapse point, both the margins reduce to zero and the corresponding load is considered as the maximum permissible loading.Fig. 5. VIP algorithm2.2. Voltage Stability Margins and the Maximum Permissible LoadingSystem reaches the maximum load point when the condition: thev load Z Z =is satisfied (Figure5).Therefore the voltage stability boundary can be defined by a circlewith a radius of the Thévenin’s impedance. For normal operation the thev Z is smaller than load Z (i.e. it is outside the circle) and the system operates on the upper part (or the stable region) of a conventional P-V curve [2].However, when thev Z exceeds load Z the system operates on the lower part (or unstable region) of the P-V curve, indicating that voltage collapse has already occurred. At the maximum power point, the load impedance becomes same as the Thévenin’s (thev L Z Z ). Therefore, for a given load impedance (load Z ), the difference between thev Z and load Z can be considered as a safety margin. Hence the voltage as given in an IEEE survey, which described (111) schemes from (17) different countries [8].Fig. 6. Load actions to prevent from voltage instability2.3. Advantages of the proposed VIP algorithmBy incorporating the measurements from other load buses (Figure 3), the proposed VIP algorithm achieves a more accurate value of load Z . The on-line tracking of thev Z is used to track system changes.The proposed improvements in the VIP algorithm will result in better control action for power system voltage stability enhancement. The control measures are normally shunt reactor disconnection, shunt capacitor connection, shunt V ARcompensation by means of SVC’s and synchrouns condensers, starting of gas turbines, low priority load disconnection, and shedding of low-priority load [8]. Figure 6 shows the most commonly used remedial actions .3. ConclusionsAn improved V oltage Instability Predictor (VIP) algorithm for improving the voltage stability is proposed in this paper. The previous VIP method [7] used measurements only from the bus where the relay is connected. The new method uses measurements from other load buses as well. The voltage instability margin not only depends on the present state of the system but also on future changes.Therefore, the proposed algorithm uses an on-line tracking Thévenin’s equivalent for tracking the system trajectory. The algorithm is simple and easy to implement in a numerical relay. The information obtained by the relay can be used for load shedding activation at the bus or V AR compensation. In addition, the signal may be transmitted to the control centre,where coordinated system-wide control action can be undertaken. The algorithm is currently being investigated on an IEEE 30 bus system and results using the improved VIP algorithm will be reported in a future publication. References[1] M.H.Haque, “On line monitoring of maximum permissible loading of a power system within voltage stability limits”, IEE proc. Gener. Transms. Distrib.,V ol. 150, No. 1, PP. 107-112, January, 2003[2] V. Balamourougan, T.S. Sidhu and M.S. Sachdev, “Technique for online prediction of voltage collapse”, IEE Proc.Gener.Transm. Distrib., V ol.151, No. 4, PP. 453-460, July, 2004[3] C.A. Anizares, “On bifurcations voltage collapse and load modeling “IEEE Trans. Power System, V ol. 10, No. 1, PP. 512-522, February, 1995[4] T.J Overbye and S.J Demarco, “Improved Technique for Power System voltage stability assessment using energy methods“, IEEE Trans. Power Syst., Vol. 6, No. 4, PP. 1446-1452, November, 1991[5] P.A Smed Loof. T. Andersson, G. Hill and D.J,”Fast calculation of voltage stability index”, IEEE Trans. Power Syst. V ol. 7, No. 1, PP. 54-64, February, 1992[6] K. Ohtsuka ,” An equivalent of multi- machine power system and its identification for on-line application to decentralized stabilizers”, IEEE Trans. Power Syst., V ol. 4 No. 2, PP. 687-693, May, 1989[7] Khoi Vu, Miroslav M Begovic, Damir Novosel, Murari Mohan Saha, “ Use of local Measurements to estimate voltage –stability margin “ IEEE Trans. Power syst. Vol. 14, No. 3, PP. 1029-1035, August, 1999[8] G.V erbic and F. Gubina “Fast voltage-collapse line protection algorithm based on local phasors”, IEE Proc.Gener.Transm. Distrib., V ol. 150, No. 4, PP. 482-486, July, 2003译文：一种特殊的预防电压波动的保护方案摘要电压的波动与输电线路的最大负载能力密切相关。

电气工程及其自动化专业英语

voltage drop 电压降 volt-ampere characteristics 伏安特性
metal-filament lamp 金属丝灯泡
carbon-filament lamp 碳丝灯泡
non-linear characteristics 非线性特性
Unit 1 Circuit Elements and Parameters
• With time-invariant currents and voltages, the magnetic anห้องสมุดไป่ตู้ electric fields of the associated electric plant are also timeinvariant. This is the reason why no e.m.f.s of self- (or mutual-)induction（自感或互感）appear in D.C. circuits, nor are there （倒装结构）any displacement currents （位移电流）in the dielectric surrounding the conductors(导体周围的电介质）.
Techniques
Unit 1 Specialized English Words
circuit components 电路元件
circuit parameters 电路参数
the dielectric 电介质
storage battery 蓄电池
electric circuit 电路
wire导线
电气工程及其自动化专业英语
Specialized English for Electrical Engineering ＆ Its Automation

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Short-circuit current1 Terms and DefinitionsThe following terms and definitions correspond largely to those defined in IEC 60 909. Refer to this standard for all terms not used in this book.The terms short circuit and ground fault describe faults in the isolation of operational equipment which occur when live parts are shunted out as a result.●Causes:1. Overtemperatures due to excessively high overcurrents.2. Disruptive discharges due to overvoltages.3. Arcing due to moisture together with impure air, especially on insulators.●Effects:1. Interruption of power supply.2. Destruction of system components.3. Development of unacceptable mechanical and thermal stresses inelectrical operational equipment.●Short circuit:According to IEC 60 909, a short circuit is the accidental or intentionalconductive connection through a relatively low resistance or impedance between two or more points of a circuit which are normally at differentpotentials.●Short circuit current:According to IEC 60 909, a short circuit current results from a shortcircuit in an electrical network.It is necessary to differentiate here between the short circuit current atthe position of the short circuit and the transferred short circuit currents in the network branches.●Initial symmetrical short circuit current:This is the effective value of the symmetrical short circuit current at the moment at which the short circuit arises, when the short circuitimpedance has its value from the time zero.●Initial symmetrical short circuit apparent power:The short circuit power represents a fictitious parameter. During theplanning of networks, the short circuit power is a suitable characteristicnumber.●Peak short circuit current:The largest possible momentary value of the short circuit occurring.●Steady state short circuit current:Effective value of the initial symmetrical short circuit current remaining after the decay of all transient phenomena.●DC aperiodic component:Average value of the upper and lower envelope curve of the short circuit current, which slowly decays to zero.●Symmetrical breaking current:Effective value of the short circuit current which flows through the contact switch at the time of the first contact separation.●Equivalent voltage source:The voltage at the position of the short circuit, which is transferred to the positive-sequence system as the only effective voltage and is used for the calculation of the short circuit currents.●Superposition method:The superposition method considers the previous load of the network before the occurrence of the short circuit. It is necessary to know the load flow and the setting of the transformer step switch.●Voltage factor:Ratio between the equivalent voltage source and the network voltage Un,divided by 3.●Equivalent electrical circuit:Model for the description of the network by an equivalent circuit.●Far-from-generator short circuit:The value of the symmetrical AC periodic component remains essentiallyconstant.●Near-to-generator short circuit:The value of the symmetrical AC periodic component does not remain constant. The synchronous machine first delivers an initial symmetrical short circuit current which is larger than twice the rated current of the synchronous machine.●Positive-sequence short circuit impedance:p••• The impedance of the positive-sequence system as seen from theposition of the short circuit.● Negative-sequence short circuit impedance:The impedance of the negative-sequence system as seen from theposition of the short circuit.● Zero-sequence short circuit impedanceThe impedance of the zero-sequence system as seen from the position of the short circuit. Three times the value of the neutral point to ground impedance occurs here.● Short circuit impedance:Impedance required for calculation of the short circuit currents at the position of the short circuit.1.2 Short circuit path in the positive-sequence systemFor the same external conductor voltages, a three-pole short circuit allows three currents of the same magnitude to develop between the threeconductors. It is therefor only necessary to consider one conductor in further calculations. Depending on the distance from the position of the short circuit from the generator, here it is necessary to consider near-to-generator andfar-from-generator short circuits separately.For far-from-generator and near-to-generator short circuits, the short circuit path can be represented by a mesh diagram with AC voltage source, reactances X and resistances R (Figure 1.2). Here, X and R replace allcomponents such as cables,conductors, transformers, generators and motors.Fig. 1.2: Equivalent circuit of the short circuit current path inthe positive-sequence systemThe following differential equation can be used to describe the short circuitprocesswhere w is the phase angle at the point in time of the short circuit. This assume that the current before S closes (short circuit) is zero. The inhomogeneous first order differential equation can be solved by determining the homogeneous solution ik and a particular solution i²k.The homogeneous solution, with the time constant g = L/R, solution yields: For the particular solution, we obtain:The total short circuit current is composed of both components:The phase angle of the short circuit current (short circuit angle) is then, in accordance with the above equation,For the far-from-generator short circuit, the short circuit current is therefore made up of a constant AC periodic component and the decaying DC aperiodic component. From the simplified calculations, we can now reach the following conclusions:●The short circuit current always has a decaying DC aperiodiccomponent in addition to the stationary AC periodic component.●The magnitude of the short circuit current depends on the operatingangle of the current. It reaches a maximum at c = 90 (purelyinductive load). This case serves as the basis for furthercalculations.●.The short circuit current is always inductive.1.4 Methods of short circuit calculationThe equivalent voltage source will be introduced here as the only effective voltage of the generators or network inputs for the calculation of short circuit currents. The internal voltages of generators or network inputs are short circuited, and at the position of the short circuit (fault position) the value ( is used as the only effective voltage (Figure 1.4).●The voltage factor c [5] considers (Table 1.1):●The different voltage values, depending on time and position●The step changes of the transformer switch●That the loads and capacitances in the calculation of the equivalentvoltage source can be neglected●The subtransient behavior of generators and motors●This method assumes the following conditions:●The passive loads and conductor capacitances can be neglected●The step setting of the transformers do not have to be considered●The excitation of the generators do not have to be considered●The time and position dependence of the previous load (loadingstate) of the network does not have to be consideredFig. 1.4: Network circuit with equivalent voltage sourcea) three-phase network, b) equivalent circuit in positivesequence system1.4.2 Superposition methodThe superposition method is an exact method for the calculation of the short circuit currents. The method consists of three steps. The voltage ratios and the loading condition of the network must be known before the occurrence of the short circuit. In the first step the currents, voltages and the internal voltages for steady-state operation before onset of the short circuit are calculated (Figure 1.5b). The calculation considers the impedances, power supply feeders and node loads of the active elements. In the second step the voltage applied to the fault location before the occurrence of the short circuit and the current distribution at the fault location are determined with a negative sign (Figure 1.5c). This voltage source is the only voltage source in the network. The internal voltages are short-circuited. In the third step both conditions are superimposed. We then obtain zero voltage at the fault location. The superposition of the currents also leads to the value zero. The disadvantage of this method is that the steady-state condition must be specified. The data for the network (effective and reactive power, node voltages and the step settings of the transformers) are often difficult to determine. The question also arises, which operating state leads to the greatest short circuit current. Figure 1.5 illustrates the procedure for the superposition method.Fig. 1.5: Principle of the superposition methoda) undisturbed operation, b) operating voltage at the faultlocation, c) superposition of a) and b)1.4.3 Transient calculationWith the transient method the individual operating equipment and, as a result, the entire network are represented by a system of differential equations. The calculation is very tedious. The method with the equivalent voltage source is a simplification relative to the other methods. Since 1988, it has been standardized internationally in IEC 60 909. The calculation is independent of a current operational state. In thisbook, we will therefore deal with and discuss the method with the equivalent voltage source.1.5 Calculating with reference variablesThere are several methods for performing short circuit calculations with absolute and reference impedance values. A few are summarized here and examples are calculated for comparison. To define the relative values, there are two possible reference variables.For the characterization of electrotechnical relationships we require the fourparameters:● Voltage U in V● Current I in A● Impedance Z in W● Apparent power S in VA.Three methods can be used to calculate the short circuit current:1. The Ohm system: Units: kV, kA, V, MVA2.The pu system:This method is used predominantly for electricalmachines; all four parameters u, i, z and s are given as per unit (unit = 1).The reference value is 100 MVA. The two reference variables for thissystem are UB and SB.Example: The reactances of a synchronousmachine Xd, X¢d, X²d are given in pu or in % pu, multiplied by 100 %.3.The %/MVA system:This system is especially well suited for the fastdetermination of short circuit impedances. As formal unit only the %symbol is add.短路电流1 术语和定义以下术语和定义对应IEC 标准60 909。

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