岑華蒙畢業(yè)設(shè)計(jì)外文翻譯SVC與STATCOM在電力系統(tǒng)中應(yīng)用的效益

1、廣西科技大學(xué)畢業(yè)設(shè)計(jì)外文翻譯 院 別 電氣與信息工程學(xué)院 專 業(yè) 電氣工程與自動化 班 級 電氣101班 學(xué) 號 201000307027 姓 名 岑華蒙 指導(dǎo)教師 周曉華 2013年12月28日Benefits of SVC and STATCOM for ElectricUtility Application Abstract- Examination of the behavior of SVCs and STATCOMs in electric power systems is presented. The paper is based on analytical and simula

2、tion analysis, and conclusions can be used as power industry guidelines. We explain the principle structures of SVCs and STATCOMs, the models for dynamic studies, and the impact of these devices on steady state voltage and transient voltage stability. Sensitivity analysis is provided which shows the

3、 impact of SVCs and STATCOMs with regard to network strength. Harmonic issues, space requirements, and price discussions are also briefly addressed. Index Terms Dynamic Compensators, SVC, STATCOM, Short Circuit Capacity, Gain Sensitivity, Short Term Voltage Stability, HarmonicsI. INTRODUCTIONSHUNT-c

4、onnected static var compensators (SVCs) are used extensively to control the AC voltage in transmission networks. Power electronic equipment, such as the thyristor controlled reactor (TCR) and the thyristor switched capacitor (TSC) have gained a significant market, primarily because of well-proven ro

5、bustness to supply dynamic reactive power with fast response time and with low maintenance.With the advent of high power gate turn-off thyristors and transistor devices (GTO, IGBT, ) a new generation of power electronic equipment, STATCOM, shows great promise for application in power systems 3,4.Thi

6、s paper aims to explain the benefits of SVCs and STATCOMs for application in utility power systems. Installation of a large number of SVCs and experience gained from recent STATCOM projects throughout the world motivates us to clarify certain aspects of these devices.II. BASIC DESCRIPTIONThis sectio

7、n explains briefly the basic configuration of SVCs and STATCOMs:A. SVCThe compensator normally includes a thyristor-controlled reactor (TCR), thyristor-switched capacitors (TSCs) and harmonic filters. It might also include mechanically switched shunt capacitors (MSCs), and then the term static var s

8、ystem is used. The harmonic filters (for the TCR-produced harmonics) are capacitive at fundamental frequency. The TCR is typically larger than the TSC blocks so that continuous control is realized. Other possibilities are fixed capacitors (FCs), and thyristor switched reactors (TSRs). Usually a dedi

9、cated transformer is used, with the compensator equipment at medium voltage. The transmission side voltage is controlled, and the Mvar ratings are referred to the transmission side.The rating of an SVC can be optimized to meet the required demand. The rating can be symmetric or asymmetric with respe

10、ct to inductive and capacitive reactive power. As an example, the rating can be 200 Mvar inductive and 200 Mvar capacitive, or 100 Mvar inductive and 200 Mvar capacitive.B. STATCOM The voltage-sourced converter (VSC) is the basic electronic part of a STATCOM, which converts the dc voltage into a thr

11、ee-phase set of output voltages with desired amplitude, frequency, and phase. There are different methods to realize a voltage-sourced converter for power utility application. Based on harmonics and loss considerations, pulse width modulation (PWM) or multiple converters are used.Inherently, STATCOM

12、s have a symmetrical rating with respect to inductive and capacitive reactive power. For example, the rating can be 100 Mvar inductive and 100 Mvar capacitive. For asymmetric rating, STATCOMs need a complementary reactive power source. This can be realized for example with MSCs.VII. THE FUNCTIONAL R

13、ATING CONCEPTTraditionally, SVCs of a common design have been used to handle different types of network problems. The trend today, however, is to tailor SVCs for their intended use. This is important in order to make SVCs cost efficient.For steady state voltage support, i.e., to follow the daily loa

14、d pattern, bulk reactive power combined with stepless smooth voltage control is desired. Vernier voltage regulation can be provided by a TCR running in parallel with harmonic filters. The bulk reactive power is provided by mechanically switched capacitor banks (MSCs) or reactors (MSRs) governed by t

15、he SVC controller. Thus SVCs serve the purpose of continuously maintaining a smooth voltage, piloting the MSC switching.If the task is to support a system limited by post contingency voltage instability or unacceptable voltage levels, a large amount of quickly controllable reactive power is needed f

16、or a short time duration. An SVC with additional TSCs is an excellent choice. Post recovery voltage support may also be necessarythis is then preferably provided by MSCs governed by the SVC.For temporary over voltages, large inductive reactive power is needed for a short period of time. The standard

17、 TCR has some short-time over current capability. This capacity can easily be extended by lowering its steady state operating temperature and by “under sizing” the reactors.A. Enhanced SVCsThe SVC characteristic at depressed voltage can be efficiently improved by adding an extra TSC. This branch is

18、intended to operate only during undervoltage conditions. It can be added without introducing additional cost in other parts of the SVC. Most important is that the current rating or the voltage capability of the power transformer does not need to be increased. Power transformers allow large overcurre

19、nt during limited time (IEEE C57-115 can be used as a guide for available capacity). In many cases three times overload in current for 10 seconds is available. The additional TSC rating is typically in the range of 50 to 100% of the SVC rating.B. SVC Short Term OverloadThe maximum power from an SVC

20、at a given voltage is determined by its reactance. No overload capacity is available unless the reactance is lowered, e.g., by adding a TSC. For overvoltages, however, the SVC reactance is no longer the limiting factor; instead the current in components defines the limit. In most cases the thyristor

21、s set the limit. The design is made so that the thyristors are running at a maximum allowed temperature at maximum steady state system voltage. A margin to destructive temperatures is reserved in order to handle fault cases. The Forbes 500 kV static var system near Duluth Minnestoa USA is an interes

22、ting example of an Enhanced SVC 5. VIII. HARMONICSBoth SVCs and STATCOMs generate harmonics. The TCR of an SVC is a harmonic current source. Network harmonic voltages distortion occurs as a result of the currents entering the power system. The STATCOM is a harmonic voltage source. Network voltage ha

23、rmonic distortion occurs as a result of voltage division between the STATCOM phase impedance and the network impedance.The major harmonic generation in SVCs is at low frequencies; above the 15th harmonic the contribution is normally small. At lower frequencies the generation is large and filters are

24、 needed. SVCs normally have at least 5th and 7th harmonic filters. The filter rating is in the range of 2550% of the TCR size.STATCOMs with PWM operation have their major harmonic generation at higher frequencies. The major contributions are at odd multiples of the PWM switch frequency; at even mult

25、iples the levels are lower. The harmonic generation decays with increasing frequency. STATCOMs might also generate harmonics in the same spectra as the conventional SVCs. The magnitudes depend on converter topology and the modulation and switching frequency used. In most cases STATCOMs as well as SV

26、Cs require harmonic filters.IX. FOOTPRINTMore and more frequently the footprint available for prospective STATCOMs or SVCs is restricted. The trend is, as in many other fields, more capacity on less space. Requirements for extremely tight designs, however, result in higher costs. In general the foot

27、print issue seems not to hinder the utilization of STATCOMs or SVCs, but occasionally, STATCOM has been preferred based on anticipated smaller footprint.When comparing SVCs with STATCOMs, it is tempting to assume that the latter will fit within a much smaller footprint, as the passive reactive eleme

28、nts (air core reactors and high voltage capacitor banks) are “replaced” with semiconductor assemblies. In the authors opinion, this assumption however remains to be practically proved. The main reason for this is that the voltage sourced converter concepts applied in STATCOMs to date have been built

29、 with several (even as many as eight) inverter bridges in parallel. This design philosophy implies many current paths, high fault currents and complex magnetic interfaces between the converters and the grid. All in all, not all STATCOMs come out as downsized compared to SVCs. Also the higher losses

30、in the STATCOM will require substantially larger cooling equipment. However, as the STATCOM technology evolves, including the use of very compact inverter assemblies with series connected semiconductor devices, and with pulse width modulation, there is a definite potential for downsizing.In the case

31、 of SVCs, the industry has a long product development where, when necessary, measures have been taken to downsize the installation. Such measures include elevated design of apparatuses, stacking of components (reactors and capacitors), vertical orientation of busbars and use of non-magnetic material

32、 in nearby structures. In a few extreme cases iron core reactors have been utilized in order to allow installation in very tight premises. In addition the development of much higher power density in high power thyristors and capacitors contributes to physically smaller SVCs.X. LIFE CYCLE OR EVALUATE

33、D COSTSIt is the authors experience that the investment cost of SVCs is today substantially lower than of comparable STATCOMs. As STATCOMs provides improved performance, it will be the choice in the cases where this can be justified, such as flicker compensation at large electrical arc furnaces or i

34、n combination with active power transfer (back-to-back DC schemes). The two different concepts cannot be compared on a subsystem basis but it is clear that the cost of the turn-off semiconductor devices used in VSC schemes must come down significantly for the overall cost to favor the STATCOM. In ot

35、her industries using high power semiconductors, like electrical traction and drives, the mainstream transition to VSC technology is since long completed and it is reasonable to believe that transmission applications, benefiting from traction and drive developments, will follow. Although the semicond

36、uctor volumes in these fields are relatively small, there is potential for the cost of STATCOMs to come down.Apart from the losses, the life cycle cost for STATCOM and SVCs will be driven by the efforts required for operation and maintenance. Both technologies can be considered maintenance freeonly

37、12 man-days of maintenance with a minimum of equipment is expected as an annual average. The maintenance is primarily needed for auxiliary systems such as the converter cooling and building systems. In all, the difference in the cost for these efforts, when comparing STATCOM and SVC, will be negligi

38、ble.XI. LOSSESThe primary losses in SVCs are in the “step-down” transformers, the thyristor controlled air core reactors and the thyristor valves. For STATCOMs the losses in the converter bridges dominate. For both technologies the long-term losses will depend on the specific operation of each insta

39、llation. The evaluation of investments in transmission has also increasingly included the costs during the entire life cycle, not only the initial investment. Losses will then be increasingly important. With a typical evaluation at $3000/kW (based on 30 years), and additional average evaluated losse

40、s of say 300 kW (compared to an SVC), the additional burden on the STATCOM is significant. The evaluated losses at full output will contribute significantly to this, but with less weight on these the difference will be much smaller. Here the evolution does not help the STATCOM as its adequate perfor

41、mance is assumed to be achieved with high frequency PWM, implying that the losses will be quite high even at small reactive power output.We expect most utilities to operate their facilities close to zero Mvar output, in order to have SVCs or STATCOMs available for dynamic voltage support. In these c

42、ases both technologies will operate with well below 0.5% losses (based on “step-down” transformer rating). However the losses will typically increase quite rapidly should the operating point be offset from zero. This is valid for both SVCs and STATCOMs. SVCs will frequently operate with both switche

43、d capacitors and controlled reactors at the same time, while converter losses of STATCOMs will increase rapidly with output current. The losses of STATCOMs at rated output will be higher than for comparable SVCs.XII. CONCLUSIONSWe have examined the performance of SVCs and STATCOMs in electric power

44、systems. Based on the analytical and simulation studies, the impact of SVCs and STATCOMs on the studied power system is presented. It was shown that both devices significantly improve the transient voltage behavior of power systems. Though SVCs and STATCOMs work on different principles, their impact

45、 on increasing power system transmission capacity can be comparable. Specifically, we describe “ enhanced” SVCs with voltage recovery performance similar to STATCOMs. Other issues such as losses, footprint, harmonics, etc., must be examined for each scenario for an optimum investment.SVC與STATCOM在電力系

46、統(tǒng)中應(yīng)用的效益摘要：提出了對電力系統(tǒng)中SVC和STATCOM的性能檢測。本文是基于分析和仿真分析的結(jié)論可以作為電力行業(yè)指導(dǎo)方針。我們解釋了SVC和STATCOM的原理結(jié)構(gòu)，動態(tài)研究模型，以及這些設(shè)備的穩(wěn)態(tài)電壓和暫態(tài)電壓穩(wěn)定性的影響。靈敏度分析顯示了SVC和STATCOM對網(wǎng)絡(luò)性能的影響。諧波問題，空間需求和成本的討論也作了簡要介紹。關(guān)鍵詞：動態(tài)補(bǔ)償器，SVC，STATCOM，短路容量，增益靈敏度，短期電壓穩(wěn)定，諧波1 引言并聯(lián)連接的靜止無功補(bǔ)償器（SVC時(shí)）被廣泛用于控制交流電壓的傳輸網(wǎng)絡(luò)。電力電子設(shè)備，如晶閘管控制電抗器（TCR）與晶閘管投切電容器（TSC）已經(jīng)獲得了很大的市場，主要是因?yàn)榱?/p>

47、好的魯棒性提供動態(tài)無功功率具有快速響應(yīng)時(shí)間和較低的維護(hù)。隨著大功率門可關(guān)斷晶閘管和晶體管器件（GTO，IGBT，.）的問世新一代電力電子設(shè)備，STATCOM在電力系統(tǒng)中，顯示出巨大的應(yīng)用前景3,4。本文的目的是解釋SVC和STATCOM在電力系統(tǒng)中的應(yīng)用的好處。從近期安裝大量SVC和STATCOM的項(xiàng)目在世界各地取得的經(jīng)驗(yàn)促使我們澄清這些設(shè)備的某些方面。2 基本介紹本節(jié)簡要解釋了SVC和STATCOM的基本配置：2.1 SVC補(bǔ)償器一般包括一個(gè)晶閘管控制電抗器（TCR），晶閘管投切電容器（TSC）和諧波濾波器。這還包括機(jī)械開關(guān)并聯(lián)電容器（MSC），然后使用長期靜態(tài)VAR系統(tǒng)。諧波濾波器（用于T

48、CR生產(chǎn)的諧波）是電容的基本頻率。該TCR通常比TSC塊較大，使得連續(xù)的控制得以實(shí)現(xiàn)。其他可選擇是固定電容器（FCs），與投切電感（TSR）。通常在中壓補(bǔ)償器設(shè)備使用一個(gè)專用變壓器。發(fā)送側(cè)的電壓被控制，且兆伏評級是指傳輸方。SVC的評級可以優(yōu)化,以滿足所需的需求。評級可以是對稱的或不對稱的相對于電感和電容的無功功率，作為一個(gè)例子,評級可以是200Mvar電感和200Mvar電容，或100Mvar電感和200Mvar電容。2.2 STATCOM電壓源變換器（VSC）是一種靜止同步補(bǔ)償器，其將直流電壓轉(zhuǎn)換成輸出電壓與期望的振幅，頻率和相位的三相組的基本電子部件。有不同的方法來實(shí)現(xiàn)電壓源轉(zhuǎn)換器，省電

49、實(shí)用的應(yīng)用程序。基于諧波和損失的考慮，脈沖寬度調(diào)制（PWM）或多個(gè)轉(zhuǎn)換器的使用。本質(zhì)上，STATCOM具有相對于電感和電容的無功功率對稱的評級。例如，評級可以是100無功電感和100無功電容。對于不對稱的評級，STATCOM需要一個(gè)互補(bǔ)的無功功率源。這可以實(shí)現(xiàn)，例如用MSC。7 功能等級的概念傳統(tǒng)上,SVC的常見的設(shè)計(jì)已被用于處理不同類型的網(wǎng)絡(luò)問題。今天的趨勢，然而，是定制的SVC作擬定用途。這是很重要的,為了使SVC成本效率更高。對于穩(wěn)態(tài)電壓支持，即要遵循日常負(fù)載模式，散裝無功功率加上無級平滑的電壓控制是需要的。游標(biāo)電壓調(diào)節(jié)可通過TCR的運(yùn)行與諧波濾波器并聯(lián)設(shè)置。大部分無功功率是通過由SVC

50、控制器管轄機(jī)械開關(guān)電容器組（MSC）或反應(yīng)器（MSR）提供的。因此SVC提供持續(xù)保持平穩(wěn)電壓的目的，試行MSC切換。如果任務(wù)是支持系統(tǒng)故障后的電壓不穩(wěn)或不可接受的電壓水平的有限，大量快速可控的無功功率是需要一個(gè)短的持續(xù)時(shí)間。一個(gè)SVC附加TSC是個(gè)不錯(cuò)的選擇?；謴?fù)后的電壓支持也可能是必要的，這然后優(yōu)選通過由SVC控制的MSC提供。對于暫時(shí)過電壓，大型感應(yīng)所需無功功率是一個(gè)很短的時(shí)間周期。標(biāo)準(zhǔn)的TCR具有一定的短時(shí)過載電流能力。這種能力可以很容易地?cái)U(kuò)展，通過降低其穩(wěn)態(tài)操作溫度和“上漿”反應(yīng)堆。7.1 增強(qiáng)的SVCSVC的特性在低電壓可以通過增加一個(gè)額外的TSC有效地改進(jìn)。這個(gè)分支的目的只有在欠壓

51、條件下進(jìn)行操作。它可以在SVC的其他部分沒有引入額外的成本增加。最重要的是，目前電源變壓器的額定電流或電壓能力并不需要增加。電源變壓器在有限的時(shí)間內(nèi)允許大過電流(IEEE c57 - 115可以用作有效容量指南)。在許多情況下，3倍過載電流為10秒是可用的。額外的TSC的評級通常被設(shè)定在50100的SVC等級的范圍內(nèi)。7.2 SVC短時(shí)過載從SVC的給定電壓的最大功率是由它的電抗決定的。無過載容量可用，除非電抗降低，例如，通過添加一個(gè)TSC。對于過電壓，然而，SVC電抗不再是限制因素；相反，由元件的電流極限定義的。在大多數(shù)情況下，各晶閘管設(shè)置的限制。該設(shè)計(jì)是由使晶閘管的電壓在一個(gè)允許的最大溫度

52、，最大穩(wěn)定狀態(tài)系統(tǒng)運(yùn)行。一個(gè)邊緣破壞性的溫度以在處理故障情況下被保留。美國福布斯附近的德盧斯的500 kV靜態(tài)VAR系統(tǒng)是一個(gè)有趣的增強(qiáng)型SVC  5 的例子。8 諧波SVC和STATCOM兩個(gè)產(chǎn)生諧波。SVC的TCR是一個(gè)諧波電流源。網(wǎng)絡(luò)諧波電壓失真的發(fā)生是由于電流輸入電力系統(tǒng)的結(jié)果。該STATCOM是一個(gè)諧波電壓源。電網(wǎng)電壓諧波失真的發(fā)生是STATCOM相阻抗與網(wǎng)絡(luò)之間的阻抗分壓的結(jié)果。諧波主要是SVC在低頻產(chǎn)生的，第十五以上的諧波貢獻(xiàn)通常是很小的。在較低的頻率所需要產(chǎn)生的較大過濾器。SVC通常至少有5次和7次的諧波濾波器。該過濾器的評級是在的TCR大小的25-50的范圍內(nèi)。STATCOM的PWM操作其主要的諧波產(chǎn)生在更高的頻率。主要貢獻(xiàn)是在PWM開關(guān)頻率的奇數(shù)倍;在偶數(shù)倍的水平較低。該諧波隨頻率的增加產(chǎn)生衰減。STATCOM還可能在相同的光譜與常規(guī)的SVC產(chǎn)生諧波。幅值依賴于轉(zhuǎn)換器的拓?fù)浣Y(jié)構(gòu)和所使用的調(diào)制和開關(guān)頻率。在大多數(shù)情況下STATCOM以及SVC需要諧波濾波器。9 安裝越來越頻繁地