電氣工程及其自動化電壓波動中英文對照外文翻譯文獻(xiàn)

1、中英文資料翻譯原文：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 sour

2、ces 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 Th e venin?s equivalent of the netwo

3、rk 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; Vol

4、tage instability; VIP algorithm.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

5、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

6、 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

7、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 i

8、n gaining insight into the cause of stability problems0.To overcome the above disadvantages several techniques have been proposed in the literature, such as bifurication theory3, energy method, eigen value method5,multiple load flow solutions method 6 etc.Reference 7 proposed a simple method, which

9、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 cl

10、oser 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 Th e venin?sequivalent, which is obtained from two measurementsat different times. For a more exact estimation, one requires

11、 two different load measurements.This paper proposes an algorithm to improve the robustness of the VIP algorithm by including additional measurementsfrom surrounding load busesand also taking into consideration local load changes at neighboring buses.Proposed MethodologyThe VIP algorithm proposed in

12、 this paper uses voltage and current measurements on the load buses and assumes that the impedance of interconnecting linesZ12 ,Z13) are known, as shown in (Figure 1). The current flowing from the generator bus to the load bus is used to estimate Th e venin?equivalent for the system in that directio

13、n. Similarly the current flowing from other load bus (Figure 2) is used to estimateequationsover theTh e venin?aequivalent from other direction. This results in following (Figure 3). Note that the current coming from the second load bus transmission line was kept out of estimation in original (VIP)

14、algorithm._1Vi(ZliZth1 ) -V2(Zi2 )=Eth1(Zth1 )1一二一_1 一一V2(Zl2Zth2 )-Vi(Zi2 )=Eth2(Zth2 )2(-71Eth1 (Zth1 )V1 (Zth1) I E1342億由2)2億由2) =Where IE1 and IE2 are currents coming fromEquation (1)-(4) can be combined into a matrix form:4Th &enin buses no.1 and 2.ZlJ+乙2+ Zth1-Zi2- Zth10Y 1一乙214.4Z +7+7ZL2Z12Z

15、th20-Z 1Zth2* M2一乙h1-40乙h0Eth10-Z JZth20Z iZth2上由2 一-0 10I E1J E2 15the voltage on busesUsing the first 2 rows in the system Equations (1)-(4), 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 a

16、ssumes that all Th e venin?s parameters are constant at the time of estimation.MZJ+zJ+zJV2j-l- Z12，6Where, y1 =Zli y12 =Z12and y2 =ZL2The system equivalent seen from bus no.1 is shown in Figure 3. Figure 4(a) shows the relationship between load admittances (y1 and y2) and voltage at bus no.1. Power

17、delivered to bus no.1 is ( ) and it is a function of(Zli,Zl2).Si =V：* 丫口7Equation 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 connectionsFig. 2. 1-Bus modelFig. 3. System equivalent as se

18、en by the proposed VIP relay on bus #1 (2-bus model)(a)Voltage Profile(b) Power ProfileFig. 4. Voltage and power profiles for bus #1On-Line Tracking of Th e venin s ParametersTh e venin?s parameters are the main factors that decide the maximum loading of the load bus and hence we can detect the volt

19、age collapse. In Figure3, Eth can be expressed by the following equation:8Eth =Vload. ZthIV and I are directly available from measurements at the local bus. Equation (8) can be expressed in the matrix form as shown below.Vrl 0Vi 0 1B=Eth (r ) I 10 - I rEth(i)Rth ILXth0 000 1 -I-0 00Ij0Ir0910The unkn

20、own parameters can be estimated from the following equation:AtAX =AtB11Note 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:? T

21、here must be a significant change in load impedance in the data window of at least two set of Measurements.? For small changes in Th e venin?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

22、 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 commu

23、nication 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 described6.stability margin (VSM) due to impedances can be expressed as (VSMZ); where subscript z denotes the impedance.T

24、herefore we have:VSMzZLoadLoadev12The above equation assumes that both load impedance%, Z2) 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 load

25、s are functions of time. The maximum critical loading point is then given by Equation(13): TOC o 1-5 h z 嚴(yán)心=013dtExpressing voltage stability margin due to load apparent power as ( VSMS), wehave:U Critical-VSMs 二 S WSL0ad14SNote that both VSMZ and VSMS are normalized quantities and their values decr

26、ease 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 algorithmVoltage Stability Margins and the Maximum Permissible LoadingSystem reaches the maximum load point when the condi

27、tion:Z10adi = Zthev is satisfied (Figure5).Therefore the voltage stability boundary can be defined by a circlewith a radius of the The venin?s impedance. For normal operatievniShsmallerthan Zload (i.e. it is outside the circle) and the system operates on the upper part (or thestable region) of a con

28、ventional P-V curve2.However, when Zthev exceedsZ10ad the system operates on the lower part (orunstable 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 The venin?s(ZL =Zthev). Therefore, for a given lo

29、ad impedance Z10ad ), the difference betweenFig. 6. Load actions to prevent from voltage instabilityZthevand Z10ad can be considered as a safety margin. Hence the voltage as given in an IEEE survey, which described (111) schemes from (17) different countrie8.Advantages of the proposed VIP algorithmB

30、y incorporating the measurements from other load buses (Figure 3), the proposed VIP algorithm achieves a more accurate value ofZ10ad . The on-line tracking of Zthev is used to track system changes.The proposed improvements in the VIP algorithm will result in better control action for power system vo

31、ltage stability enhancement. The control measures are normally shunt reactor disconnection, shunt capacitor connection, shuntAR compensation by means of SVC?s ansynchrouns condensers, starting of gas turbines, low priority load disconnection, and shedding of low-priority load 8. Figure 6 shows the m

32、ost commonly used remedial actions .ConclusionsAn improved Voltage Instability Predictor (VIP) algorithm for improving the voltage stability is proposed in this paper. The previous VIP method used measurements only from the bus where the relay is connected. The new method uses measurements from othe

33、r 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 ohne tracking Th e venin?s equivalent for tracking the system trajectory. The algorithm is simple and easy to implement in a n

34、umerical relay. The information obtained by the relay can be used for load shedding activation at the bus or 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

35、 on an IEEE 30 bus system and results using the improved VIP algorithm will be reported in a future publication.ReferencesM.H.Haque, “On line monitoring of maximum permissible loading of a power system within voltage stability limits IEE proc. Gener. Transms. Distrib .,Vol. 150, No. 1, PP. 107-112,

36、January, 2003V. Balamourougan, T.S. Sidhu and M.S. Sachdev,a Technique for online prediction of voltagecollapse IEE Proc.Gener.Transm. Distrib. , Vol.151, No. 4, PP. 453-460, July, 2004C.A. Anizares,“ On bifurcations voltage collapse and load modEEiE Trans. Power ”System, Vol. 10, No. 1, PP. 512-522

37、, February, 1995T.J Overbye and S.J Demarco,“ Improved Technique for Power System voltage stabilityassessment using energy methods ”, IEEE Trans. Pwer Syst., Vol. 6, No. 4, PP. 1446-1452, November, 1991P.A Smed Loof. T. Andersson, G. Hill and D.J, Fast calculation of voltage stability irtdeXE Trans.

38、 Power Syst. Vol. 7, No. 1, PP. 54-64, February, 1992K. Ohtsuka ,“ An equivalentlof machine power system and its identification for on-lineapplication to decentralized stabilizers IEEE Trans. Power Syst., Vol. 4 No. 2, PP. 687-693, May,Use of local1989Khoi Vu, Miroslav M Begovic, Damir Novosel, Mura

39、ri Mohan Saha,Measurements to estimate voltage -stability margin IEEE Trans. Power syst. Vol. 14, No. 3, PP.Fas-tcvoollatapgsee line protection algorithm based on local phasors1029-1035, August, 1999G .Verbic and F. GubinaIEE Proc.Gener.Transm. Distrib ., Vol. 150, No. 4, PP. 482-486, July, 2003譯文：一

40、種特殊的預(yù)防電壓波動的保護(hù)方案摘要電壓的波動與輸電線路的最大負(fù)載能力密切相關(guān)。輸電系統(tǒng)中電能的傳輸依 賴于輸電線路的拓?fù)浣Y(jié)構(gòu)，發(fā)電和負(fù)載，以及無功電源的出處。一種用于分析電壓 波動的方法是電壓波動的預(yù)測（VIP）。由繼電器測量變電所連接到線路上的電路 的電流和電壓。根據(jù)測量結(jié)果，借助戴維南定理估算出輸送到變電所線路和從變 電所提供的負(fù)載的阻抗。本文描述了一個測量相鄰系統(tǒng)母線并考慮到的負(fù)荷預(yù)期 變化的擴(kuò)展的VIP技術(shù)。關(guān)鍵詞：最大負(fù)載能力；電壓波動；VIP算法。.簡介寬松的政策迫使發(fā)電企業(yè)要更好地利用電力系統(tǒng)中的輸電。這導(dǎo)致了輸電量的增加，降低了輸電利潤和減小了電壓安全裕度。操作一個有足夠安全裕

41、度的電力系統(tǒng)，在系統(tǒng)的使用信息中估算當(dāng)前操作點(diǎn) 的最大允許負(fù)載是必要的。一個電力系統(tǒng)的最大負(fù)載不是一個固定的值而是取決 于各種各樣的因素，比如輸電線路的拓?fù)?、無功電源的出處和他們的位置等等。 決定最大允許負(fù)載，在電壓穩(wěn)定極限內(nèi)，在電力系統(tǒng)運(yùn)行和規(guī)劃研究中已成為一 個非常重要的問題。常見的P-V或V-Q曲線通常當(dāng)作一個評彳S電壓穩(wěn)定的依據(jù)，進(jìn) 而為在電力系統(tǒng)電壓崩潰端尋找最大負(fù)載提供依據(jù)。這些曲線常規(guī)的方法是在 大量負(fù)載流運(yùn)行使用的情況下產(chǎn)生的。雖然這樣的過程已經(jīng)可以自動化，但它們是耗時的，在發(fā)現(xiàn)穩(wěn)定性問題的起因時不易提供一些有用的信息2 o為了克服上述缺點(diǎn)的多個方法已經(jīng)在文獻(xiàn)上提到，比如分叉理

42、論網(wǎng)，能量法4、本征值法5,多個負(fù)載流解法6等。參考口提出了一個簡單的方法，它不需要離線的模擬和訓(xùn)練。電壓指標(biāo)預(yù)測 方法（VIP） 7是在本地測量值（電壓和電流）的基礎(chǔ)上，產(chǎn)生一個連接到母線上估 算優(yōu)點(diǎn)和缺點(diǎn)的輸電系統(tǒng)，并將它與當(dāng)?shù)氐男枨髮Ρ?。估算出最接近本地需求?輸電量，更為緊迫的是電壓波動。該方法的主要缺點(diǎn)是在戴維南定理的估算，它在不同時刻獲得兩個測量值。對于一個更精確的估值,一般需要兩個不同的負(fù)荷測量值。本文提出了一種提高穩(wěn)定性算法的算法，包括周圍負(fù)載母線的額外的測量值 外也考慮到相鄰總線之間局部的負(fù)載變化。.提出的方法VIP算法在本文中提到在負(fù)載母線和互連線（乙2 ,乙3）的假設(shè)阻抗

43、在已知的情況下使用電壓和電流測量，如下所示（圖1）。發(fā)電機(jī)負(fù)載母線的電流被用來估計戴維南等效的輸電方向。類似于用從其他負(fù)載母線（圖2）的電流來估計戴維南 等效的其他方向。這個結(jié)果在以下方程式（圖3）。注意在輸電線路上來自第二負(fù) 載母線的電流被排除在最初的估算（VIP）算法一1_1、 .一1、_. 1、V2&242 )-乙2廣5億3)V(Zl1Zth1 ) -V2(Z12 )=Eth1(Zth1 )1 1Eth1(Zth1)V1(Zth1) - 1 E1一 一 二 一 Eth2(Zth2 ) -V2(Zth2 )=由戴維南定理得來自第一和第二母線的電流IE1和IE2。方程（1）-（4）可以組合為

44、一個矩陣形式r .11111Zl1+Z12+Zth1-Z12-Zth1-1.X n1z Z12Z L2 *Z2Zth2 011-Zth10Zth1_4_-Zth2001V11-Zth2 * V20Eth1Zth2，fth2 一一0 10I E1E2 1使用第一行系統(tǒng)方程（1）-（4）中的2,在母線1和2上的電壓可以發(fā)現(xiàn)如以下方 程式（6）所示。從方程式（6）中我們可以看到，電壓是一個阻抗的函數(shù)。請注意這 個方法是假定所有戴維南的參數(shù)是常數(shù)時的估算。Vjz4_4_4_ L1 41 Z12-Z121- Zi2Zl2 Zth2 Z12*%jEth2 Zth261在y1 =ZL144y12 =Zi2

45、和y2 =Zl2 中系統(tǒng)等效理解為母線1如圖3所示。圖4（a）顯示了負(fù)載通道（y1和y2）和母線1 電壓之間的關(guān)系。電力輸送到母線1是（S）,它是一個（ZL1, ZL2）. Si=V12*yL1的函數(shù)7占“。圖1.3母線系統(tǒng)連接圖2.1母線模型圖3.系統(tǒng)等效為被提議的VIP轉(zhuǎn)接到母線#1(母線#2模型)方程式7如圖4(b) “形象化”繪制并且最大負(fù)載點(diǎn)取決于系統(tǒng)軌跡”超過頂(a)電壓分布圖(b)功率分布圖圖4.母線#1的電壓和功率分布圖即時跟蹤戴維南的參數(shù)戴維南的參數(shù)是決定負(fù)載母線最大負(fù)載的的主要因素，因此我們可以檢測輸 電系統(tǒng)電壓崩潰。在圖3,日可以用以下的方程式表示：8Eth oad. 2

46、由 I電壓和電流可以從測量本地母線直接得到o方程式(8)可以用矩陣形式表達(dá)，如下所示V 0Vi gEh(r)1Eth(i)Rth1 00 00 10 0- I r0- I i.0IJ0Ir09B= A X10未知參數(shù)可以從以下方程式的估算11AT AX = AtB注意，上述所有數(shù)量的計算是函數(shù)的時間和在滑動窗口的有限的離散數(shù)據(jù)樣 本之內(nèi)計算，最好長度是短的。在額外的需求下做出可行的估算：?必須有一個顯著的變化，負(fù)載阻抗數(shù)據(jù)窗口至少兩組測量值。?對于戴維南參數(shù)在一個特殊的數(shù)據(jù)窗口小的變化，該算法可以正確地估算除一個突然大的變化以外，估算的過程推遲到下一個數(shù)據(jù)窗口的到來。?這種監(jiān)視裝置基于上述原理

47、可以用來強(qiáng)加限制裝載在每個母線 ，和流負(fù)載 超過限制時。它也可以用來加強(qiáng)現(xiàn)有的電壓控制器。 協(xié)調(diào)控制同樣可以得到在交 流是否空閑的情況下。一旦我們有了時間序列的電壓和電流，我們可以通過使用參數(shù)估算算法估算未知參數(shù)，如卡爾曼濾波方法描述6 0穩(wěn)定裕度（VSM）由于阻抗可以表示為（VSMz）;在下標(biāo)z表示阻抗。因此我們有：VSMZZLoadevZLoad12上述方程式假設(shè)兩個負(fù)載阻抗（Zi, Z2）是在一個穩(wěn)定的速度下減少，所以電力送到母線1將根據(jù)方程 增加。然而一旦它達(dá)到飽和點(diǎn)的時候電力再一次 開始減少?，F(xiàn)在，假設(shè)兩個負(fù)載是時間的函數(shù)。最大的臨界負(fù)載點(diǎn)方程式（13）給出：SCritical ;至=013dt電壓穩(wěn)定裕度表示由于負(fù)載視在功率為（VSMs）,我們有：U Critical -14VSMs S0adS注意，VSMZ和VSM s兩個都是標(biāo)準(zhǔn)化的定量和隨著負(fù)載的增加它們的價值減少。在電力系統(tǒng)電壓崩潰點(diǎn)，同時兩個裕度減少到零和相應(yīng)的負(fù)載被視為最大允許負(fù)載。電壓穩(wěn)定裕度和最大允許加載系統(tǒng)達(dá)到最大負(fù)載點(diǎn)當(dāng)滿足條件：