外文翻譯---無(wú)功功率補(bǔ)償?shù)淖钚逻M(jìn)展

1、<p><b>　　附錄</b></p><p><b>　　附錄一 英文資料</b></p><p>　　Recent advances in var compensators</p><p>　　G]~ZA JOOS . Department of Electrical and Computer Engine

2、ering, Concordia</p><p>　　University 1445, de Maisonneuve W, Montreal, Canada H3G 1M8</p><p>　　e-mail: geza@ece.concordia.ca</p><p>　　Abstract. Static var compensators have been, f

3、or many years, an essential co</p><p>　　mponent in the operation of power transmission systems. They are part of a fam-</p><p>　　ily of devices known as Flexible AC Transmission System (FACTS) d

4、evices. The advent of large capacity force-commutated semiconductor switches allows many developments in power electronic converters to be applied to the implem-</p><p>　　entation of high power compensators.

5、 This paper describes the principles of co-</p><p>　　ntrolled reactive power compensation, particularly in the context of power syst-</p><p>　　ems. It focuses on active static power converter-ba

6、sed compensators and discu-</p><p>　　sses issue related to the power circuit topology and control techniques including the impact of Pulse Width Modulation (PWM) techniques. Compensators based on current and

7、 voltage source converters and on ac controllers, both in the shunt and series configurations, are covered. Methods to enhance power capacity usin</p><p>　　-g multi-level and multi-pulse arrangements are dis

8、cussed.</p><p>　　Key words. Reactive compensation; power electronic converters; powers ystems.</p><p>　　Introduction</p><p>　　Reactive power (var) compensation has long been recogn

9、ized as an essential fun</p><p>　　ction in the operation of power systems. At the distribution level, it is used to i-</p><p>　　-mprove the power factor and support the voltage of large industri

10、al loads, such as line commutatedthyristor drives and electric arc furnaces. Reactive power co-</p><p>　　mpensation also plays a crucial role at the transmission level in supporting the l-</p><p&g

11、t;　　-ine voltage and stabilizing the system. Rotating synchronous condensers and m-</p><p>　　echanically-switched capacitor and inductor banks have been replaced in the 19</p><p>　　70s by thyris

12、tor-based technologies: in typical installations, a thyristor-contro-</p><p>　　lled reactor (TCR) provides variable lagging vars, and fixed or thyristorswitched capacitors (TSC) provide the leading vars. The

13、 combination of both devices in parallel allows continuous control of vars over a wide range of values, from lea</p><p>　　-ding to lagging vars (Gyugyi 1979). A large number of units have been succes</p&g

14、t;<p>　　-sfully installed and operated for many years. At the same time, the potential of var compensators based on static power converters have also been recognized an</p><p>　　-d a number of configu

15、rations proposed and investigated (Gyugyi 1979).</p><p>　　However, thyristor technology only allows the implementation of lagging var generators, unless complex force-commutation circuits are used. This draw

16、back has been eliminated with the introduction of Gate Turn-Off (GTO) thyristors (La</p><p>　　-rsen et al 1992). This has allowed the development of a number of configuratio</p><p>　　-ns based o

17、n the use of synchronous voltage sources (Gyugyi 1993). Prototype GTO-based var compensation units, known as STATCOMs have been installed and tested by utilities (Schauder etl 1995). The STATCOM and other static var comp

18、ensators have recently been grouped, together with other types of transmiss</p><p>　　-ion system control devices, under the heading of Flexible AC Transmission System (FACTS) devices.</p><p>　　R

19、eactive power compensators are typically connected in shunt across transmis</p><p>　　-sion and distribution systems. An alternative connection, the series connection, has recently received much attention fro

20、m utilities (Gyugyi et al 1996). Techno</p><p>　　-logical solutions have been developed to solve problems associated with insula</p><p>　　-ting the equipment from ground and the full potential o

21、f series connections can now be exploited. The latest development in var compensation technology has b</p><p>　　-een the combination of series and shunt static compensators into one unit, know</p><

22、;p>　　-n in the area of power systems under the name of Unified Power Flow Controll</p><p>　　-er, or UPFC (Gyugyi 1992).</p><p>　　Static power converters have been successfully applied to a la

23、rge number of power conversion problems at low and medium power levels. However adapting these solutionsto high power transmission and distribution levels raises special issues. Although the capacity of power semiconduct

24、or switching devices has gra</p><p>　　-dually increased, large ratings still require combining devices in series and par</p><p>　　-allel. In addition to the large power handling capacity, static

25、 compensators must have very high efficiency, since losses have a negative impact on both the initial and operating costs of the power system. Switching losses are therefore a prima</p><p>　　-ry concern and

26、switching frequencies must therefore be kept low. This may res</p><p>　　-ult in large harmonic waveform distortion, unless special power circuit configu</p><p>　　-rations are used.</p>&l

27、t;p>　　This paper reviews the various methods available for generating reactive pow</p><p>　　-er (var) by means of force-commutated static power converters, taking into acc</p><p>　　-ount the

28、above constraints. It discusses topologies suitable for use with devices such as GTOs and the more recently available high power IGBTs and addresses switch gating issues, including the use of Pulse Width Modulation (PWM)

29、 tech</p><p>　　-niques. Methods for designing high power converters suitable for transmission level compensation are presented, particularly multilevel and multi-module top</p><p><b>　　-ol

30、ogies.</b></p><p>　　2. Principles of var compensation</p><p>　　Var compensation can be viewed as the injection of reactive power, leading or lagging, into the ac system. In its simplest fo

31、rm, reactive power injection is ach</p><p>　　-ieved by inserting fixed capacitors or inductors in either series or shunt into the ac system. Assuming a compensation reactance Xc is inserted in a transmission

32、 system, the generated var Qc is derived as follows.</p><p>　　Figure 1. Principles of vat compensation in transmissi6n systems. (a) Shunt compensation. (b) Series compensation. </p><p>　　(a) For

33、 the shunt connection, figure la,</p><p>　　a reactive current Icq is generated, allowing in particular line voltage support at the point of connection, Vc:</p><p>　　(b) For the series connection

34、, figure lb the reactive impedance Xc partially com</p><p>　　-pensates the line reactance, and a reactive voltage Vcq is inserted in series, the current Ic being the line current:</p><p>　　In ad

35、dition to the lack of controllability of the reactive power injection, fixed capacitive compensation can lead to ac system instability, such as in the pheno</p><p>　　-menon known as subsynchronous resonance,

36、 or SSR, associated with series c-</p><p>　　ompensation (Ooi & Dai 1993; Gyugyi et al 1996). In order to control the amo</p><p>　　-unt of reactive power injected, the reactive impedance must

37、 be varied. Equiva-</p><p>　　lently, a variable current or variable voltage is injected into the system, emulat-</p><p>　　ing a variable reactance, figure 1 b.</p><p>　　The apparent

38、 reactive impedance of a fixed element can be varied using ac s-</p><p>　　witches, or ac controllers. On the other hand, the current or voltage required to e</p><p>　　-mulate a variable reactanc

39、e can be injected into the ac system by means of syn</p><p>　　-thetic sources, which can be realized using static power converters (Agaki et al 1984; Campos e t a l 1994). In addition to providing reactive p

40、ower, these active compensators can also supply real power, either transiently or for a number of periods of the ac supply. This real power can be used to dampen power system oscillations or temporarily support the power

41、 system voltage under fault condi</p><p>　　-tions. Furthermore, since the compensator is fully controllable, resonant freq</p><p>　　-uencies associated with the use of capacitors are eliminated

42、and the potential for instability suppressed.</p><p>　　Figure 2. Thyristor-controlledv ariable reactance compensators.</p><p>　　(a) Thyristor-controlled reactor (TCR) and thyristor-switched capa

43、citor (TSC) shunt compensator? (b) Transfer characteristics of a TCR with fixed capacitor. (c) Thyristor-controlled series capacitor compensator (TCSC).</p><p>　　3. AC controller-based structures</p>

44、<p>　　3.1 Conventional thyristor-controlled reactor</p><p>　　The basic scheme, figure 2a, consists of an ac controller which varies the appa-</p><p>　　rent inductance of the inductor as ref

45、lected onto the ac line (Gyugyi 1979). The thyristor-controlled reactor (TCR) provides continuously controllable lagging vars and is biased using fixed, or more often, thyristor-switched capacitors(TSC). The injected var

46、s can therefore be continuously adjusted from leading to lagging, figure 2b. However, the var injection or voltage regulation capability of the com</p><p>　　-pensator is limited by the value of the reactance

47、 and is therefore line voltage de</p><p>　　-pendent, figure 2b. Advantages of the system however include ruggedness, high efficiency, good dynamic performance and competitive cost. The disadvantages include

48、injection into the line of large low frequency harmonic currents, domin-</p><p>　　ant being the 5th and 7th components (300 and 420 Hz for a 60 Hz system) for the basic ac controller. Harmonics can be moved

49、to higher frequencies by para-</p><p>　　lleling units and using special transformer configurations. Harmonic currents ca</p><p>　　-n be reduced by means of tuned LC filters. These however are co

50、stly and can c</p><p>　　-ause voltage oscillations resulting from the added system resonant frequencies.</p><p>　　3.2 Force-commutated ac controller structures</p><p>　　An alternati

51、ve to the thyristor-based ac controllers is the force-commutated ac controller, figure 3a (Jin et a11994; Venkataramanan & Johnson 1997). The use of force-commutated switching devices removes the requirement for oper

52、ating the converter in synchronism with the ac supply and allows gating the switches more than once per cycle. Arbitrary gating patterns can be implemented, partic</p><p>　　-ularly PWM patterns (Jin et a1199

53、4). The principles of PWM pattern generat-</p><p>　　ion are explained in § 6.2. Assuming the inductor current is sinusoidal, a pattern with constant duty cycle yields ac line side currents that only con

54、tain harmonics around the switching frequency and its multiples. This pattern is simple to impl</p><p>　　-ement and allows control of the equivalent inductance; therefore, the amount of vars absorbed can be

55、varied from 0 to a maximum value. Since losses associated with switching large currents at high voltages increase significantly with switch</p><p>　　-ing frequency, this frequency must be kept low, typically

56、 a few hundred hertz for GTOs. In order to reduce the distortion of injected currents, while keeping the switching frequency low, elementary modules are connected in parallel, figure 3b, and gated so that harmonics are m

57、inimized . This also allows the realization of var compensators of large ratings (Lopes et al 1996).</p><p>　　Figure 3. Variable reactance scheme based on force-commutated ac controllers (Bias capacitorsart

58、not shown). (a) Basic ac controller structure. (b)Multi-module converter</p><p><b>　　附錄二 中文翻譯</b></p><p>　　無(wú)功功率補(bǔ)償?shù)淖钚逻M(jìn)展</p><p>　　作者：G]~ZA JOOS ，電氣與計(jì)算機(jī)工程系， 肯考迪婭大學(xué)， 1455年納芙

59、鎢，加拿大蒙特利爾H3G 1M8 ，電子郵箱： geza@ece.concordia.ca </p><p><b>　　摘要</b></p><p>　　靜止無(wú)功補(bǔ)償器已有多年的發(fā)展歷史，是電力傳輸系統(tǒng)中一個(gè)必不可少的環(huán)節(jié)。他們是被稱作柔性交流輸電系統(tǒng)（FACTS）設(shè)備中的一種。 大容量半導(dǎo)體開關(guān)轉(zhuǎn)換器的出現(xiàn)給電力電子轉(zhuǎn)換器帶來(lái)多方面的發(fā)展，并用于實(shí)施大功率補(bǔ)償器。

60、本文介紹控制無(wú)功補(bǔ)償?shù)脑瓌t，特別是在電力系統(tǒng)中。它的重點(diǎn)是積極的靜態(tài)功率轉(zhuǎn)換器為基礎(chǔ)的補(bǔ)償， 并討論電源電路拓?fù)浣Y(jié)構(gòu)和控制技術(shù)有關(guān)的問題， 包括脈沖寬度調(diào)制（PWM）技術(shù)的影響。 基于電流和電壓源轉(zhuǎn)換器和交流控制器的補(bǔ)償器， 其分流和一系列的配置都包括在內(nèi)。討論了提高發(fā)電能力利用多層次，多級(jí)脈沖調(diào)制的方法。</p><p>　　關(guān)鍵詞：無(wú)功補(bǔ)償，電力電子變換器，電力系統(tǒng)。</p><p>

61、<b>　　1.導(dǎo)言</b></p><p>　　無(wú)功功率（var）補(bǔ)償長(zhǎng)期以來(lái)被確認(rèn)為電力系統(tǒng)運(yùn)轉(zhuǎn)中的一項(xiàng)基本職能。在分配方面，它是用來(lái)改善功率因數(shù)和支持大型工業(yè)電壓負(fù)荷，如線路晶閘管驅(qū)動(dòng)器和電弧爐。無(wú)功補(bǔ)償在傳輸級(jí)別的作用關(guān)鍵在支持線路電壓和穩(wěn)定系統(tǒng)。 旋轉(zhuǎn)同步冷凝器和機(jī)械開關(guān)電容和電感已被上世紀(jì)70年代的以可控硅整流器的基礎(chǔ)的技術(shù)所取代：在典型安裝， 晶閘管可控電抗器（TCR）提供了變

62、量滯后無(wú)功，以及固定或晶閘管投切電容器（TSC）提供了超前的無(wú)功。在兩者并聯(lián)的結(jié)合設(shè)備，使無(wú)功功率在一個(gè)廣泛的范圍內(nèi)可連續(xù)控制，從無(wú)功功率超前到滯后（Gyugyi，1979年） 。許多單位已成功安裝這些設(shè)備，并運(yùn)行多年。與此同時(shí)，潛在的基于靜態(tài)功率轉(zhuǎn)換器的無(wú)功補(bǔ)償器也已經(jīng)被認(rèn)識(shí)，并且提出了一些配置建議并調(diào)查（Gyugyi，1979年）。</p><p>　　然而，可控硅整流技術(shù)，只允許執(zhí)行滯后無(wú)功發(fā)生器，除非使用

63、復(fù)雜的電力變換電路。隨著可關(guān)斷晶閘管（GTO）的引進(jìn)這一缺陷已經(jīng)消除了（拉爾森等，1992年 ） 。這允許發(fā)展一些配置的基礎(chǔ)上利用同步電壓源（ Gyugyi，1993年）。以原型可關(guān)斷晶閘管為基礎(chǔ)的無(wú)功補(bǔ)償單元，被稱為為靜止同步補(bǔ)償器STATCOMS，現(xiàn)已安裝和并通過(guò)了公用測(cè)試（Schauder等，1995）。STATCOMS和其他靜止無(wú)功補(bǔ)償器最近已經(jīng)歸類，連同其他類型的傳輸系統(tǒng)控制裝置，統(tǒng)稱為柔性交流傳輸系統(tǒng)（FACTS）設(shè)備。&l

64、t;/p><p>　　無(wú)功補(bǔ)償器并聯(lián)連接在輸電和配電系統(tǒng)中非常典型。一種供選擇的連接，串聯(lián)連接，最近受到了公共事業(yè)的重視（Gyugyi等，1996年）。技術(shù)上的方法已經(jīng)足夠成熟去以解決設(shè)備從地面的絕緣問題，并且可以充分開發(fā)串聯(lián)潛能。無(wú)功補(bǔ)償技術(shù)的最新發(fā)展是由串聯(lián)和并聯(lián)靜止補(bǔ)償器組合成的單元，在電力系統(tǒng)中被稱作統(tǒng)一潮流控制器或UPFC(Gyugyi，1992年)。</p><p>　　靜態(tài)功率轉(zhuǎn)

65、換器已成功地用于解決大量的在低壓和中壓水平無(wú)功功率補(bǔ)償問題。但是這些解決方案，以適應(yīng)高功率傳輸和分配水平提出了特別的問題。雖然大功率半導(dǎo)體開關(guān)設(shè)備的容量逐漸增加，仍然需要大級(jí)別的聯(lián)合裝置應(yīng)用于串聯(lián)和并聯(lián)設(shè)備。除了大功率處理能力之外，靜態(tài)補(bǔ)償器必須有非常高的效率，因?yàn)楣β蕮p會(huì)失產(chǎn)對(duì)電力系統(tǒng)的初級(jí)和生產(chǎn)成本產(chǎn)生負(fù)面影響。因此，開關(guān)損耗成為首要關(guān)注的問題并且開關(guān)頻率必須保持在較低水平。這可能導(dǎo)致大量諧波波形失真，除非使用特殊的電源電路的配置。

66、</p><p>　　本文綜述了各種可用于產(chǎn)生無(wú)功功率（var）的方法，通過(guò)使用強(qiáng)制換向靜態(tài)功率轉(zhuǎn)換器，同時(shí)考慮到上述限制。它討論了拓?fù)溥m合用設(shè)備，如GTOs以及最近提供的大功率IGBT并且論及門控開關(guān)的問題，包括使用脈沖寬度調(diào)制（PWM）技術(shù)。適于傳輸水平的大功率轉(zhuǎn)換器的設(shè)計(jì)方法的介紹，特別是多層次，多模塊拓?fù)浣Y(jié)構(gòu)。</p><p><b>　　2.無(wú)功補(bǔ)償原理</b&g

67、t;</p><p>　　無(wú)功補(bǔ)償可以視為向交流系統(tǒng)注入超前或滯后的無(wú)功功率。無(wú)功功率注入實(shí)現(xiàn)的最簡(jiǎn)單的方式就是插入固定電容器或電感器，串聯(lián)或并聯(lián)在交流系統(tǒng)中。假設(shè)補(bǔ)償電抗XC插入傳輸系統(tǒng)，所產(chǎn)生的無(wú)功QC推導(dǎo)如下。</p><p>　?。╝）并聯(lián)補(bǔ)償 （b）串聯(lián)補(bǔ)償</p><p>　　圖1 輸電系統(tǒng)無(wú)功補(bǔ)償原則</p><p>　

68、?。?）在并聯(lián)連接中，圖如1（a）所示，產(chǎn)生一個(gè)無(wú)功電流Icq，從而在連接點(diǎn)補(bǔ)償一定的線電壓，VC ：</p><p>　　（2）在串聯(lián)連接中，如圖1（b）所示，無(wú)功阻抗XC 補(bǔ)償部分線路電抗，且在串聯(lián)處獲得補(bǔ)償電壓Vcq ，電流IC為線電流：</p><p>　　除了缺乏可控的無(wú)功功率注入，固定電容補(bǔ)償可能會(huì)導(dǎo)致交流系統(tǒng)的不穩(wěn)定，例如與串聯(lián)補(bǔ)償相關(guān)的被稱為次同步諧振或SSR的現(xiàn)象（Ooi

69、＆Dai，1993年；Gyugyi等1996年）。為了控制注入的無(wú)功功率值，無(wú)功電抗必須是多種多樣的。等效的可變電流或可變電壓注入系統(tǒng)，模擬一個(gè)可變電抗，如圖1b。</p><p>　　使用交流開關(guān)或交流控制器可以使一個(gè)有固定元素的的無(wú)功電抗可變。另一方面，電流或電壓必須要仿真一個(gè)可變電抗，通過(guò)綜合性來(lái)源可注入交流系統(tǒng)，它可以用靜態(tài)功率轉(zhuǎn)換器來(lái)實(shí)現(xiàn)（Agaki等，1984 ;Ca1994年）。除了提供無(wú)功功率，這

70、些超前的補(bǔ)償器也可以提供有功功率，無(wú)論是瞬時(shí)的或一定時(shí)期的。提供的有功功率可以用來(lái)抑制電力系統(tǒng)振蕩或暫時(shí)支持電力系統(tǒng)電壓故障。此外，由于補(bǔ)償器是完全可控的，使用電容器消除了共振頻率并消除潛在的不穩(wěn)定隱患。</p><p>　　(a)TCR+TSC (b)TCR+FC的電壓-電流特性</p><p>　　(c)晶閘管控制串聯(lián)電容器TCSC</p><p

71、>　　圖2 晶閘管控制可變電抗補(bǔ)償器</p><p>　　3.交流控制器為基礎(chǔ)的結(jié)構(gòu)</p><p>　　3.1常規(guī)晶閘管可控電抗器</p><p>　　常規(guī)晶閘管可控電抗器的基本結(jié)構(gòu)如圖2（a）所示，包含一個(gè)交流控制器，它能夠調(diào)整互感器的自感系數(shù)，并將變化反應(yīng)到交流線路（Gyugyi，1979年） 。晶閘管可控電抗器器（TCR）提了連續(xù)可控的滯后的無(wú)功功率

72、，并偏重于或更頻繁的與固定的晶閘管投切電容器（TSC）并聯(lián)使用 。因此，注入的無(wú)功功率可以連續(xù)不斷調(diào)整，從無(wú)功功率超前到滯后，如圖2（b）所示。然而，由于電抗值得影響，電容器補(bǔ)償?shù)臒o(wú)功或電壓調(diào)節(jié)能力是有限的，因此，線路電壓隨之確定，如圖2（b）。可是，該系統(tǒng)有耐用，效率高，良好的動(dòng)態(tài)性能和具有成本競(jìng)爭(zhēng)力等優(yōu)點(diǎn)。缺點(diǎn)包括交流控制器注入線路大量低頻諧波電流，主要是5次和7次諧波（300和420赫茲若為60赫茲系統(tǒng)）。諧波可以轉(zhuǎn)變到更高的頻率

73、，通過(guò)并聯(lián)設(shè)備和使用特殊的變壓器配置。諧波電流可以通過(guò)LC濾波器消除。不過(guò)這是昂貴的，附加給系統(tǒng)的共振頻率可能導(dǎo)致電壓波動(dòng)。</p><p>　　3.2強(qiáng)制換向交流控制器結(jié)構(gòu)</p><p>　　這種可替代晶閘管的交流控制器就是強(qiáng)制換向交流控制器，如圖3（a）所示（Jin等,1994 ; Venkataramanan and Johnson,1997年）。使用強(qiáng)制換向開關(guān)設(shè)備滿足了在操縱轉(zhuǎn)

74、換器的時(shí)刻同時(shí)進(jìn)行交流補(bǔ)償?shù)囊螅⑶以试S在每次循環(huán)中多次使用門控開關(guān)。任意門控模式都能夠得到執(zhí)行，特別是脈寬調(diào)制PWM模式（Jin等，1994）。PWM控制模式將在后面給予介紹。假設(shè)電感電流是正弦的，一種連續(xù)占空比產(chǎn)生AC線側(cè)電流諧波的模式，只包含開關(guān)頻率及其倍數(shù)。這種模式執(zhí)行簡(jiǎn)單并允許對(duì)等效電感進(jìn)行控制，因此，無(wú)功功率吸收地范圍可從零到最大值之間變化。由于大型開關(guān)高壓電流的損失伴隨著開關(guān)頻率顯著增加，該頻率必須保持很低，對(duì)GTOs來(lái)

75、說(shuō)通常只有幾百赫茲。為了少注入的失真電流，同時(shí)保持開關(guān)頻率較低，最簡(jiǎn)單的方法就是小模塊并聯(lián)，如圖3（b）所示，并且采用門控方式，以便盡量減少諧波。這也使大容量等級(jí)的無(wú)功補(bǔ)償器得以實(shí)現(xiàn)（洛佩斯等人，1996年）。</p><p>　　圖3 基于強(qiáng)制換向交流控制器的各種電抗方案（偏置電容未顯示）</p><p>　?。╝）基本的AC控制器結(jié)構(gòu) （b）多模轉(zhuǎn)換器。</p>