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电力散文篇一:电力文章翻译

The cause of harmonic and the harmonic flow calculation in electric

power system

First, introduction an ideal electrical power system is by the sole constant frequency and the stipulation peak-to-peak value regulated voltage power supply. But in fact, as a result of the recent years along with science's and technology's unceasing development, the high efficiency traded the class equipment and the modulator use, high in the electrical power

system presses the nonlinear element which the direct current transmission the application, the massive misalignment load's appearance as well as the power supply system itself existed and so on to cause in the system's voltage waveform distortion to be getting more and more

serious, has caused the very big harm to the electrical power system, for example: Causes in the power supply system the part to lose increases, reduces current collector's service life, to disturb the communication system and so on. Serious when even can also cause equipment the damage, automatic control malfunction, relay protection misoperation, thus creates the power cut accident and so on and other questions. So-called " the friend knows other, is undefeated in many battles ", therefore, must realize to the electrical network overtone comprehensive program of public order, must make clear the overtone origin and the

electrical network in under the each different movement way the overtone tidal current

distributed situation, adopts the corresponding measure limit and the harmonic cancellation, thus changes the friendly power supply system power supply quality and guarantees system's security economy movement.

Second, electrical power system overtone's origin in the electrical power system the

overtone source is many and varied. Mainly has the following several kinds:in

1, system's each kind of misalignment current collector for example: Trades the class

equipment, the modulator, the electrification railroad, the arc furnace, fluorescence the lamp, the domestic electric appliances as well as each kind of electronic energy conservation control device and so on is the electrical power system overtone important source. Even if these equipment supplies its ideal sine wave voltage, it uses the electric current is also non-linear, namely has the harmonic current existence. And these the equipment produces the harmonic current will also pour into the electrical power system, will cause system each place voltage to have the harmonic component. These equipment's harmony the wave content decided that in its characteristic and the working condition, basically has nothing to do with the electrical power system parameter, may regard as overtone constant flow the source.

2, the power supply system itself exists the nonlinear element is overtone another origin.

These nonlinear element mainly has the transformer to stir up the capacitor which, the reactor group the magnetism leg, the alternating and direct convertor station's silicon-controlled rectifier controlling element, the silicon-controlled rectifier control and so on.

3rd, like the fluorescent lamp, the domestic electric appliances and so on single capacity is not big, but quantity and spreads very greatly in each place, electric power department with difficulty management current collector. If these equipment's current harmonics content is oversized, will then have the serious influence to the electrical power system, to this kind of equipment's current harmonics content, when manufacture namely should limit in certain quantity scope.

4, the generator send out overtone electric potential. The generator will send out the overtone electric potential at the same time also to have the overtone electric potential production, its overtone electricity the potential will be decided by generator's structure and the working condition, basically will have nothing to do with the external connection impedance.

Therefore may regard as overtone constant pressure source , but its value is very small. the three, electrical power system overtone tidal current calculates the so-called electrical power system overtone tidal current computation, is through solution network equation In=YnUn (n=3,5,7 ...... n: Agrees wave number the number. In is the overtone source load pours into electrical network's n subharmonic electric current row vector. Yn is electrical

network's n subharmonic conductance. Un is in the electrical network a various nodes bus bar n subharmonic voltage row vector). Obtains in the electrical network various nodes (bus bar) the harmonic voltage, enters to obtain in various legs' harmonic current.

When in the electrical power system the existence has the overtone source, this time in the system the contact voltage and the branch current will have the higher harmonic. For the determination harmonic voltage and harmonic current's in power supply system distribution, needed to carry on to the overtone impedance constitution equivalent circuit the tidal current computation, when simultaneously in the rectifier unit power supply system possessed

forbearance the part existed, but must act according to various legs overtone impedance the nature and the size, whether there is examined the resonant situation. carries on the overtone tidal current computation, must first determine the electrical network part's overtone

impedance. (3.1), electrical network each kind of part's overtone impedance: (1), synchronous generator's overtone impedance the qualified generator's electric potential is the pure sine, does not include the higher harmonic, its generator electric potential only exists in the fundamental wave network. in higher harmonic network, because the generator overtone electric potential is very small, this time the visible generator overtone electric potential is zero. Therefore its and so on the value electric circuit is the junctor end and neutral point overtone reactance .

And XGn=nXG1-------------(1) in the formula XG1 is when a fundamental wave generator's zero foreword, the positive sequence or the negative sequence reactance, has this subharmonic foreword characteristic to decide , if needs to take into account the network to lose, regarding the generator, may its impedance angle according to 85 degrees estimates, regarding the transmission line, part's and so on transformer and load equivalent generators, may its

impedance angle according to 75 degrees estimates. . (2), transformer's overtone impedance the electrical power system overtone's peak-to-peak value often is elevates along with the

frequency weakens, therefore in the fundamental wave tidal current computation high tension line , often neglects transformer's initiation leg and the capacitance between turns particularly. When calculates the harmonic current, only considers transformer's leakage reactance, and thought that recognizes the frequency with the harmonic order to be proportional. Generally, as soon as transformer's equivalent circuit simplifies for links to meet the original

vice-mid-side node overtone reactance **** *** is the transformer fundamental wave leakage reactance. under higher harmonic's function, the winding internal kelvin effect and

approaches the effect to increase, by now transformer's resistance harmonic order's square was proportional approximately with the , this time's transformer overtone impedance is: Zn=sqrt(n)RT1+jnXT1-------------------------------(3) And RT1 is the fundamental wave

time-variable depressor's resistance. regarding the three-phase winding transformer, may use the star equivalent circuit, on its overtone impedance computation side Fathom. when the overtone source pours into when higher harmonic current three-phase not symmetry, then must figures out the three-phase overtone impedance according to transformer's wiring way and various forewords impedance meter . 3) reactor's overtone impedance , when only takes into account the reactor induction reactance, to the n subharmonic frequency is:

XLn=Nxl*UN/sqrt(3)IN 4), transmission line's overtone impedance the transmission line has the uniform distribution parameter electric circuit, passes through the transmission line which change positionss completely to be possible to regard as is three-phase symmetrical. in tidal current computation, usually by lumped parameter PI equivalent circuit expression. Following chart: in takes into account in the distribution characteristic situation, then: ZLn=Znsh(rnl) Yln/2=(chrnl-1)/(Znshrnl) ZN and RN respectively be regarding in thi(出自:WwW.HNNscy.Com 博 文学习 网:电力散文)s subharmonic when line's wave impedance and propagation constant. Zn=sqrt(Z0n/Y0n) Rn=sqrt(Z0nYon) Z0N and Y0N respectively be this subharmonic when transmission line unit length impedance and conductance five), load overtone impedance .When overtone tidal current computation, the fundamental wave part may pour into power regarding according to the node, but regards as in the overtone network it is the constant impedance, may think that approximately the synthesis load is an equivalent electric motor. Its synthesis load's overtone equivalent

resistance value is: ZN=SQRT (N) R1+JNX1 R1, X1 is the fundamental wave equivalent electric motor's negative sequence resistance, the reactance, its value may by this node fundamental wave voltage, power the value obtain after the conversion. the zero foreword electric current will not enter the load generally, thus in zero foreword's higher harmonic network, may neglect shoulders the leg. when after has determined in the electric circuit various electrical element's overtone impedance, may constitute an overtone function

equivalent circuit, with the aim of carrying on the computation, under when plan overtone function equivalent circuit should pay attention to the following several characteristics: (1), the overtone function's equivalent circuit, should take the rectifier unit as a center, according to actual wiring constitution, therefore the rectification installs to set regards as the overtone

source, but electrical power system's generator is not appears by the energy, but as overtone source loaded impedance part. (2), the circuit element impedance may use the famous value to carry on the computation, may also use the sign Yao value to carry on the computation. When uses famous value carries on the computation, the complete electric circuit should convert to some voltage reference, is advantageous for the analysis and the application. (3) in the general computation, part's all resistances may neglect, but when system some part occurs either close parallel or strings together the joint resonance, this time's resistance influence actually cannot neglect. (4), in harmonic current approximate calculation, what determined is the rectifier unit side total harmonic current, according to and so on overtone function the effect electric circuit, can determine various legs harmonic current and the voltage distribution. the 3.2nd, overtone tidal current calculates (3.2.1), not to allow the part network overtone tidal current to calculate

(1), symmetrical system's overtone tidal current to calculate in the symmetrical system the three-phase situation to be the same, therefore may calculate according to a situation. when has determined the rectifier unit, no matter what after one side total harmonic current, the union overtone equivalent circuit, may determine in the system network, no matter what a leg's harmonic current distribution. Then again pours into the harmonic current according to the node harmonic voltage and the node relational I=YU (in its , Y is overtone conductance), might determine each place node harmonic voltage. Then may extract the tidal current power. It counts to calculate that the step is as follows: , the basis give the operating condition, by usual tidal current computational method solution fundamental wave tidal current. , according to the overtone source working condition, determined other related parameters and need to calculate harmonic order. , calculates various parts overtone parameter, forms various

subharmonics node admittance matrix, and calculates the corresponding overtone net to pour into the electric current. , by type IN=YNUN determined that various nodes the harmonic voltage, and calculates various legs harmonic power. in which, should pay attention has the overtone injection current which the overtone instrumental measurement leaves, its phase angle is opposite in the fundamental current phase angle. Therefore after extracting the

fundamental current, must carry on the overtone injection current phase angle the revision. Similarly, the system node's power is the fundamental wave power with agrees sum of the wave power, therefore the fundamental wave pours into the power also to carry on the revision. But the linear load's place fundamental wave pours into the power not to need to

revise. (2), the symmetrical system overtone tidal current calculates in the symmetrical system, the three-phase situation is various, moreover mutual influence, must therefore

simultaneously carry on three-phase system's idea to calculate. the symmetrical net tidal

current's computation may divide into the network various subharmonics network, calculates the fundamental wave network first, after obtaining various nodes fundamental wave the

voltage, calculates various overtones tidal current according to it each injection current, then presses this overtone injection current to resolve various subharmonics net to wind the

equation, extracts various nodes various subharmonics voltage. (3.2.2), in the rectifier unit power supply system possesses forbearance the part has when the overtone tidal current to

calculate , when in the rectifier unit power supply system possesses forbearance the part exists, the capacitor to rectifier unit's phase change process and voltage current wave the shape is influential. Generally under the base frequency, the induction reactance and the capacitance leg's parameter differs really in a big way in the value, does not send produces the resonance effect, but a rectifier unit's non-sinusoidal return route, may regard as is several different frequencies and oscillation amplitude sine electric potential the comprehensive result which affects separately in the return route, because the induction reactance frequency characteristic and the capacitance frequency characteristic are just opposite, have the possibility

subharmonic both value to be close in some under the , have the resonance effect. When besides carries on the normal overtone tidal current computation, but also wants to act according to various legs overtone impedance the nature and the size, whether there is examines the resonance.

Four, summarize in the electrical power system's overtone appearance, regarding the

electrical power system movement is one kind " the pollution ". They reduced systemic voltage the ueliable profile quality, not only has affected electrical power system oneself seriously, moreover also harms the user and the periphery communications system. therefore to the electrical power system overtone's research regarding the improvement electrical energy quality, suppresses with the harmonic cancellation has vital significance .

电力散文篇二:赞美电力工人

劳动者的赞歌。

——献给长期奋战在一线的电工维修女工

无需要华丽的辞藻来赞美你

因为你既不美丽,也不伟大

维修工具却在你们粗糙灵巧的手里描绘出一幅幅绚丽的画

没有掌声,没有喝彩,没有鲜花弹指一挥间

却在工作岗位上奋战了二十多个年华其实你很美丽,也很伟大

从来就以厂为家

设备前摸爬滚打

一次次挥汗如雨

轮班抢修星光下

一个紧急的抢修电话

留下的是你匆匆的步伐

在高空也能爬上爬下

不曾说一句怨言道一声怕

走过春秋,度过冬夏

谁说你们比男爷们差

说句心里话

谁不愿穿名牌、讲品位、烫头发在花花世界里装扮潇洒

可既然来维修,既然选择他

就无畏风吹雨打,汗油交加

工具包穿过工服而挎

扳手,钳子,螺丝刀

才是你生命的牵挂

在我看来

你的装束不再那名牌之下你们在成长,你们在壮大安全与工作两手抓

创标兵,规范化

女职工也能建功立业争创神话巾帼不让须眉

英姿甲天下

电力散文篇三:经典散文诗

乡愁

作者:余光中

(中文)

小时候 ,

乡愁是一枚小小的邮票 ,

我在这头 ,

母亲在那头。

长大后 ,

乡愁是一张窄窄的船票

我在这头 ,

新娘在那头 。

后来啊,

乡愁是一方矮矮的坟墓

我在外头,

母亲在里头 。

而现在 ,

乡愁是一湾浅浅的海峡

我在这头 ,

大陆在那头。

(英文)

When I was young,, , ,

my homesickness was a small stamp,

I was here,

my mother was there.

After growing up,

my homesickness was a narrow ticket,

I was here,

my bride was there.

Later,

my homesickness was a little tomb,

I was outside,

my mother was inside.

And now,

my homesickness is a shallow strait,

I am here,

the mainland is there.

主题思想

这首诗借邮票、船票、坟墓、海峡这些具体的实物,把抽象的乡愁具体化了,变成具体可感的东西,表达作者渴望与亲人团聚,渴望祖国统一的强烈愿望。

南方的夜

我们静静地坐在湖滨,

听燕子给我们讲讲南方的静夜。

南方的静夜已经被它们带来, 夜的芦苇蒸发着浓郁的热情── 我已经感到了南方的夜间的陶醉, 请你也嗅一嗅吧这芦苇丛中的浓味。

你说大熊星总像是寒带的白熊, 望去使你的全身都觉得凄冷。 这时的燕子轻轻地掠过水面, 零乱了满湖的星影──

请你看一看吧这湖中的星象, 南方的星夜便是这样的景象。

你说,你疑心那边的白果松, 总仿佛树上的积雪还没有消融。 这时燕子飞上了一棵棕榈,

唱出来一种热烈的歌声──

请你听一听吧燕子的歌唱,

南方的林中便是这样的景象。

总觉得我们不像是热带的人, 我们的胸中总是秋冬般的平寂。 燕子说,南方有一种珍奇的花朵,

经过二十年的寂寞才开一次──

这时我胸中忽觉得有一朵花儿隐藏, 它要在这静夜里火一样地开放!

教我如何不想她

天上飘着些微云,

地上吹着些微风。

啊!

微风吹动了我头发,

教我如何不想她?

月光恋爱着海洋,

海洋恋爱着月光。

啊!

这般蜜也似的银夜,

教我如何不想她?

水面落花慢慢流,

水底鱼儿慢慢游。

啊!

燕子你说些什么话?

教我如何不想她?

枯树在冷风里摇,

野火在暮色中烧。

啊!

西天还有些儿残霞,

教我如何不想她?

刘半农 一九二〇年八月六日 伦敦

预言

作者:何其芳

这一个心跳的日子终于来临! 你夜的叹息似的渐近的足音

我听得清不是林叶和夜风的私语, 麋鹿驰过苔径的细碎的蹄声!

告诉我,用你银铃的歌声告诉我, 你是不是预言中的年轻的神? 你一定来自那温郁的南方,

告诉我那儿的月色,那儿的日光, 告诉我春风是怎样吹开百花, 燕子是怎样痴恋着绿杨。

我将合眼睡在你如梦的歌声里, 那温暖我似乎记得,又似乎遗忘。 请停下,停下你长途的奔波, 进来,这儿有虎皮的褥你坐!

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