變壓器勵磁涌流抑制外文翻譯

1、<p>　　變壓器勵磁涌流的抑制</p><p>　　變壓器勵磁涌流不僅導致繼電保護誤動，由其衍生的電網(wǎng)電壓驟降、諧波污染、和應(yīng)涌流、鐵磁諧振過電壓等都給電力系統(tǒng)運行帶來不可低估的負面影響。數(shù)十年來人們通過識別勵磁涌流特征的方法來減少繼電保護的誤動率，但并未獲得良好的回報，誤動率仍居高不下。至于對電壓驟降、諧波污染、和應(yīng)涌流等的消除更一籌莫展。究其原因是人們認為勵磁涌流的出現(xiàn)不可抗拒，只能采用“識別”的

2、對策，即“躲”的對策。其實，換個思路——“抑制”，是完全可以實現(xiàn)的，而且已經(jīng)實現(xiàn)了。 引言　　變壓器勵磁涌流與電容器的充電涌流抑制原理完全相似，電感及電容都是儲能元件，前者不容許電流突變，后者不容許電壓突變，空投電源時都將誘發(fā)一個暫態(tài)過程。在電力變壓器空載接入電源時及變壓器出線發(fā)生故障被繼電保護裝置切除時，因變壓器某側(cè)繞組感受到外施電壓的驟增而產(chǎn)生有時數(shù)值極大的勵磁涌流。勵磁涌流不僅峰值大，且含有極多的諧波及直流分量。由此對電網(wǎng)

3、及電器設(shè)備造成極為不利的影響。 1、勵磁涌流的危害性1.1 引發(fā)變壓器的繼電保護裝置誤動，使變壓器的投運頻頻失??；1.2 變壓器出線短路故障切除時所產(chǎn)生的電壓突增，誘發(fā)變壓器保護誤動，使變壓器各側(cè)</p><p>　　圖2-1為一單相變壓器結(jié)構(gòu)圖，可寫出空載時初級繞組的電壓方程</p><p>　　式中N1、R1分別為初級繞組的匝數(shù)及電阻 </p><p&g

4、t;<b>　?。?.1）可改寫為</b></p><p>　　式中α為 t=0時U1的初相角如忽略電阻R1，即 設(shè)R1=0，則得求解（2.3）式微分方程得磁通Φ的表達式為</p><p>　　依據(jù)磁鏈守恒定理，合閘瞬間磁路中磁鏈不能突變，即可求出積分常數(shù)C。式中</p><p><b>　　可寫出磁通Φ表達式</b

5、></p><p>　　式中為總磁通的幅值從式(2.6)中不難看出變壓器外施電壓u1在不同初相角α合閘時所產(chǎn)生的磁通Φ都不相同，將式(2.6)改寫為</p><p>　　式(2.7)中為暫態(tài)磁通，即偏磁，在合閘瞬間Φp的值與α有關(guān)，在90°或270°空投時Φp=0，在0°或180°空投時Φp可達峰值Φm。式(2.7)中 為穩(wěn)態(tài)磁通，為一周期函數(shù)

6、。圖2-2為空投合閘角α=0時的磁通變化曲線，圖中Φs為穩(wěn)態(tài)磁通，Φ為Φs和Φp合成的總磁通（未計及剩磁Φres），Φsat為變壓器飽和磁通。對于無損變壓器（R1=0）偏磁Φp不會衰減，如實線所示，對于有損變壓器（R1>0） </p><p>　　Φp按時間常數(shù)衰減，如虛線所示。從圖2-2中可看出在電壓相位角在θ1至θ2區(qū)間總磁通Φ大于飽和磁通Φsat，磁路飽和，因而產(chǎn)生勵磁涌流iy，iy具有間斷性。對

7、于無損變壓器Φ和iy是關(guān)于的偶對稱波形，而在iy=0的間斷角區(qū)間Φ則是關(guān)于的偶對稱波形。對于有損變壓器則Φ與iy將不再有對稱關(guān)系。當計及剩磁時，總磁通將由剩磁、偏磁（暫態(tài)磁通）及穩(wěn)態(tài)磁通三者組成。不難看出在圖2-2偏磁的情況下，如剩磁為正，則總磁通曲線向上平移，即磁路更易飽和，勵磁涌流</p><p>　　幅值會更大。如剩磁為負，則勵磁涌流將被抑制。 </p><p>　　圖2-3是鐵磁

8、材料的磁滯回線，它描述在磁路的勵磁線圈上施加交流電壓時，磁勢H也相應(yīng)的從-Hc到Hc之間變化，由H產(chǎn)生的磁通Φ（或磁通密度B=Φ/S）將在磁滯回線上作相應(yīng)的變化。如果H在回線上的某點突然減到零，則B將隨即落到對應(yīng)B軸的某點上，該點所對應(yīng)的B值即為剩磁Br。可以看出剩磁的數(shù)值和極性與切除勵磁電壓的相位角有關(guān)，如果在第Ⅰ、Ⅱ象限切斷勵磁電源（即H=0）則剩磁為正或零，在Ⅲ、Ⅳ象限切斷勵磁電源，則剩磁為負。3、勵磁涌流的抑制方法　　變壓器

9、在正常帶電工作時，磁路中的主磁通波形與外施電源電壓的波形基本相同，即是正弦波。磁路中的磁通滯后電源電壓90°，通過監(jiān)測電源電壓波形實現(xiàn)對磁通波形的監(jiān)測，進而獲取在電源電壓斷電時剩磁的極性。變壓器空投上電時產(chǎn)生的偏磁Φp也一樣，因偏磁 ，電源電壓上電時的初相角α在Ⅰ、Ⅳ象限區(qū)間內(nèi)產(chǎn)生的偏磁極性為正，而初相角α在Ⅱ、Ⅲ象限區(qū)間內(nèi)產(chǎn)生的偏磁極性為負。顯然，剩磁極性可知，偏磁極性可控，只要空投電源時使偏磁與剩磁極性相反，涌流即被抑制。

10、 　　變壓器初級電壓u、主磁通Φ、剩磁ΦRes及偏磁Φp與分閘角和合閘角的關(guān)系曲線圖,以及電源電壓u分閘初相角α’</p><p>　　性正好相反，也就是說通過分閘時測量電源電壓分閘角α’，并將α’保存下來，在下次空投變壓器時選擇在合閘角α等于α’時加上電源，偏磁就可與剩磁反向，它們的合成磁通將小于飽和磁通Φsat(曲線④)，（因飽和磁通一般選擇大于穩(wěn)態(tài)磁通峰值），磁路不會飽和，從而實現(xiàn)對勵磁涌流的抑制。由于三

11、相電源電壓在斷路器三相聯(lián)動切除時所得到的三相分閘相角各相差120°，剩磁極性也是三相各相差120°，而在三相聯(lián)動合閘時三相的合閘初相角也是相差120°，三相偏磁極性也各相差120°，這樣就自然實現(xiàn)了變壓器三相磁路中的偏磁和剩磁都是抵消的，從而避免了一定要斷路器分相分時操作才能抑制勵磁涌流的苛求，也就是說三相聯(lián)動斷路器支持對三相涌流的抑制。 由于抑制勵磁涌流只要偏磁和剩磁極性相反即可，并不要

12、求完全抵消，因而當合閘角相對前次分閘角有較大偏差時，只要偏磁不與剩磁相加，磁路就不會飽和，這就大大降低了對斷路器操作機構(gòu)動作時間的精度要求，為這一技術(shù)的實用化奠定了基礎(chǔ)。將這種抑制器與快切裝置和備自投裝置聯(lián)動即可實現(xiàn)備用變壓器按冷備用方式運行，這將大大節(jié)約變壓器熱備用方式的空載能耗。 圖3-1選錄了四條勵磁涌流I</p><p>　　分閘角α’與合閘角α對勵磁涌流的影響曲線圖3-1</p>

13、<p>　　應(yīng)該指出，變壓器斷電后留在三相磁路中的剩磁在正常情況下是不會衰減消失的，不會改變極性。只有在變壓器鐵心受到高于材料居里點的高溫作用后剩磁才會衰減或消失，但一般的電站現(xiàn)場不會出現(xiàn)這種情況。退一步講，剩磁消失是件好事，只要沒有剩磁，僅靠偏磁是不會引起磁路飽和的。</p><p>　　4、結(jié)束語　　電力變壓器空投充電相位角與前次切除電源相位角匹配原則，從理論及實踐上都證明了在使用三相聯(lián)動操作斷路

14、器時能徹底抑制勵磁涌流。同樣，電力電容器空投充電相位角與前次切除電源相位角匹配原則，也能實現(xiàn)抑制三相聯(lián)動斷路器合閘時的電容器充電涌流。這一技術(shù)對根除保護誤動、改善電能質(zhì)量、提高運行可靠性有重要意義。同樣對各種電壓等級電力系統(tǒng)的無功補償、遠距離輸電線路的串聯(lián)補償控制等也有重要意義。</p><p>　　Transformer inrush current suppression </p><p&

15、gt;　　Transformer inrush current leads not only to the protective relaying misoperation, derived from the power grid voltage sags, harmonic pollution, and the inrush current, ferromagnetic resonance overvoltage in power s

16、ystem operation, to bring the negative effect that cannot underestimate. For decades the people through the identification of inrush current feature method to reduce the relay misoperation rate, but did not gain a good r

17、eturn, malfunction rate is still high. As for the voltage sag, ha</p><p>　　Introduction </p><p>　　Transformer inrush and surge suppression capacitor chargingprinciple is completely similar to th

18、e inductance and capacitance are energy storage devices, the former does not allow current mutation, which does not allow voltage surge,power drop will induce a transient process. Access in the power transformer no-load

19、transformer outlet power failure andprotection devices to be removed, because of a side of the transformer windings to feel the surge applied voltage values ??are sometimes generated a</p><p>　　1. the danger

20、 of inrush current </p><p>　　1.1 caused by the transformer protection devices malfunction,the frequent failure of the transformer and put into operation;</p><p>　　1.2 removal of the transformer

21、short-circuit fault outlet voltage generated when the sudden increase in the protection induced by transformermalfunction, so that each side of the transformer load all thepower;</p><p>　　1.3 A power station

22、 access to a power transformer no-load inrush current generated, inducing other B power station nearby, C power station transformers are running a "and should surge" (sympathetic inrush) and false tripping, res

23、ulting in a large area power failure; large inrush currentvalue of </p><p>　　1.4 would result in electric power transformers andcircuit breakers due to excessive damage; </p><p>　　1.5-induced ov

24、er-voltage, damaged electrical equipment; </p><p>　　1.6 inrush current of the DC component lead to over-current transformermagnetization and magnetic significantly reduce themeasurement accuracy and the corr

25、ect action rate ofprotection devices; </p><p>　　1.7 magnetizing inrush current in a large number of harmonics on power quality caused by pollution.</p><p>　　1.8 caused by voltage sags or swells,

26、 affecting the normal operation of other electrical equipment. For decades, people have taken to the inrush current approach is to "hide", but because of inrush current form and characteristics ofdiversity, thr

27、ough mathematical or physical methods toidentify its characteristics difficult to improve the accuracy ofthat inrush current in this field has been a historical problem. </p><p>　　2. the magnetizing inrush c

28、urrentcauses </p><p>　　Suppressor is an important feature of the strategy adopted bymagnetizing inrush current is not "escape", but "suppression." Inrush current theory and practice that

29、can suppress or even eliminate, because the source of inrush current is generated in the transformer windings on either side felt the applied voltage increases, based on fluxconservation theorem, the windings in the magn

30、etic circuit will produce a single polarity of the magnetic bias, such as partial pole and transformer of exactly th</p><p>　　For a long time, people found it impossible to measure thetransformer polarity an

31、d remanence values, and thus had to abandon the use of the idea of partial remanence magneticoffset. Inrush current in response to the strategy does notappear on the two smooth road, a road through the control power tran

32、sformer voltage drop closing phase angle, so that it does not produce magnetic bias, in order to avoid magnetic saturation occurs when the power drops . The other way is the use of physical or mathem</p><p>

33、　　dentification with the physical and mathematical methods of magnetizing inrush current rather difficult, because the characteristics of magnetizing inrush current and a lot of factors, such as closing phase angle, the

34、electromagnetic parameters of the transformer and so on. A large number of scholars and engineers through decades of unremitting effortsstill can not find an effective way, because of its high degree of difficulty, that

35、is to "avoid" strategy difficult, the Achilles heel ofthis str</p><p>　　Transformer diagram 2-1 </p><p>　　Figure 2-1 is a single-phase transformer structure, we can write the no-load v

36、oltage of the primary winding of the equation </p><p>　　Where N1, R1, respectively, for the primary winding turns and the resistance </p><p><b>　?。?.2)</b></p><p>　　(2.1

37、) can be rewritten as Where α t = 0, U1, such as ignoring the initial phase angleresistor R1, which </p><p>　　Let R1 = 0, we obtain the solution (2.3)-type equations have an expression for the magnetic flux

38、Φ </p><p>　　Based on flux conservation theorem, in the closing momentsmagnetic flux can not change suddenly, you can find theintegration constant C. </p><p>　　The amplitude of the total flux fro

39、m equation (2.6) is not difficult to see that the applied voltage transformer u1 in the early phase angle α different when closing the magnetic fluxgenerated by Φ is not the same, the equation (2.6) is rewritten as</p

40、><p>　　(2.7) for the transient flux, that is, magnetic bias, in the closing moments Φp value of α for the 90 ° or 270 ° drop at Φp = 0, at 0 ° or 180 ° when dropped up to the peak Φm Φp . Eq

41、uation (2.7) in for the steady-state flux, as a periodic function. Figure 2-2 for the drop-closing angle α = 0, the flux curve, the steady-state flux diagram Φs, Φ is Φs and Φp total flux synthetic (not taking into accou

42、nt the remanence Φres), Φsat for the transformer saturation flux. For the lossless transformer (R</p><p>　　Closing angle α = 0, the flux curve of Figure 2-2 </p><p>　　Dashed line. As can be seen

43、 from Figure 2-3 in the voltage phase angle range θ1 to θ2 greater than the total flux Φsaturation flux Φsat, magnetic saturation, resulting inrush current iy, iy has a discontinuity. </p><p>　　For the lo

44、ssless transformer Φ and iy is about even symmetry of the waveform, while the discontinuity in theiy = 0 is the angular range of Φ the even symmetric waveform. For Φ and iy is detrimental tothe transformer will no long

45、er symmetrical relationship. </p><p>　　When taking into account the remanence, the remanence will be the total magnetic flux, magnetic bias (transient flux) andsteady-state flux of the three components. Diff

46、icult to see inFigure 2-2 Bias in the case, such as remanence is positive, the total flux curve upward shift, that more saturated magnetic circuit, inrush current amplitude will be greater. If remanence is negative, the

47、inrush current is suppressed. </p><p>　　Core material hysteresis loop in Figure 2-3 、</p><p>　　Figure 2-2 is the hysteresis loops of ferromagnetic materials,which describes the excitation coi

48、l in the magnetic circuit on the AC voltage applied, the corresponding magnetic potential H-Hc to Hc from between the change in magnetic flux Φ generated by H (or magnetic flux density B = Φ / S) in the corresponding hys

49、teresis loop changes. If the H line at some point suddenly back to zero, then B will then fall into the B-axiscorresponds to a certain point, the point corresponding to theB value is t</p><p>　　3.the magneti

50、zing inrush current suppression method </p><p>　　Transformer energized during normal working hours, the main magnetic flux in the applied voltage waveform and the waveform is basically the same, that is a si

51、ne wave. Magnetic flux lags the supply voltage of </p><p>　　90 °, by monitoring the supply voltage waveform to achieve the flux waveform monitoring,then get off when the supply voltage polarity remanenc

52、e. Dropon the power transformer magnetic bias Φp also generatedas a result of magnetic bias, the power supply voltage when the initial phase angle α in Ⅰ, Ⅳ quadrant bias generated within the range of magnetic polarity i

53、s positive, while the initial phase angle α in Ⅱ, ⅲ quadrant bias generated within the range of magnetic polarity is negative. Clearly, th</p><p>　　Figure 3-1for the transformer primary voltage u, the main m

54、agnetic flux Φ, and the bias magnetic remanence ΦRes Φp with sub-gate the relationship between the angle and closing angle curve, and the sub-gate supply voltage u beginning ofthe phase angle α 'with the remanence ΦR

55、es curve. The main transformer in the steady state flux Φ lag the supply voltage u 90 °, tTransformer no-load power generated when the magnetic bias must correspond with the steady state voltage u at power point on

56、the curve </p><p>　　As long as the partial inhibition of inrush current and remanent magnetic polarity opposite to, are not required to fully offset,so when the closing angle relative to a greater angle of t

57、he previous sub-gate bias, as long as no magnetic bias and remanence are added together, the magnetic circuit not saturated, which greatly reduces the operating time of circuit breaker operating mechanism precision requi

58、rements for the practical application of this technology laid the foundation.Suppressor and f</p><p>　　Figure 3-3presents selected four inrush current Iy and thesub-gate angle α 'and the closing angle α

59、of the curve, you can see, in the closing angle α of 90 ° or 270 °, drop the transformer inrush current and transformer before sub-sub-gate angle has nothing to do, because the transformer primary voltage over

60、peak power does not produce magnetic bias, regardless of whether the original transformer magnetic saturation remanence will not. Of course, if you use three-phase circuit breaker is not pos</p><p>　　Trippin

61、g angle α 'and closing angle α of the inrush current of Figure 3-1 </p><p>　　It should be noted, after a stay in the three-phase power transformer magnetic circuit remanence under normal circumstances wi

62、ll not decay away, and not to change polarity.Only in the transformer core material above the Curie point bythe high temperature will decay or disappear after the remanence, but generally the power station site will not

63、happen. Say the least, remanence disappeared a good thing,as long as there is no residual magnetism, magnetic bias alone will not cause magnetic saturatio</p><p>　　4.Conclusion </p><p>　　Drop ch

64、arging power transformer phase angle phase anglewith the previous removal of the power matching principle, in theory and practice have proved that the joint operation in the use of three-phase circuit breaker can be comp

65、letely suppressed when the inrush current. Similarly, the power capacitor charging phase angle with the last drop cut powerphase angle matching principle, can be achieved when thecircuit breaker closing inhibit the inter