外文翻譯----基于LabVIEW的電流互感器校驗(yàn)儀

1、附錄a labview based instrument current transformer calibratorxin ai hal bao y.h. song 1) north china electric power university, beijing, china 107206 2) brunel university. ukabstractthe virtual instrument (vi) mainly refers to build all kinds of instruments by software such as labview, which likes a r

2、eal instrument build in a computer. its main characteristics are flexibility, multi-functions, multiple uses for one pc computer, giving high performance, and is less costly. in this paper, the vi technology is applied to the test and measurement of instrument current transformer (ta). by using the

3、labview, the ta accuracy calibrator was developed. this virtual t.4 calibrator can automatically measure the accuracy of t.4 and can indicate the ratio error and phase error curves. the tests and calibration for the ta show that the virtual ta calibrator can be used in place of the traditional calib

4、rator and is much better than the traditional one.keywords：instrument current transformer (ta), ta calibrator, virtual instruments, labview.i. introductionsince 1992 the vxibus rev.1.4 standard was established by the united states and labview was presented by the national instruments co.(nl), the vi

5、rtual instrument (vi) have lain the foundation for its commercial use. the main characteristic of virtual instrument is that it makes instruments by software. most of the traditional instrument can be developed by vi. the vi is a real instrument made by the personal computer.the instrument current t

6、ransformer (ta) is widely used in all kinds of current measurement and it has the functions of protection, isolation and extending the measuring range. with the rapid development of computer measurement and control technology, and with the sequent emergence of current transformer and transducer, the

7、re is an increasing number of current transformers with high accuracy and low secondary current. the standard ta secondary current is usually 1a or 5a: some non-standard ta secondary current may be 0 1a or lower. although we have the technique to make this kind of calibrator by means of hardware suc

8、h as single chip computer and electronic circuit, dsp and so on, it will cost too much money for these no-standard calibrator and will take too much time and the calibrator made by these hardware mill not be satisfactory in both function and practicality for designing all kinds of new ta.the calibra

9、tor that adopts vi technology not only can meet the requirements of the traditional one but also can satisfy customers with such advantages as multi-functions, convenience, and high ratio between performance and cost. the experiment results indicate that the virtual calibrator can provide excellent

10、condition for ta measurement and design. the vi technology and personal computer must be widely used in the area of calibration on instrument transformer. the working principle of ta calibratorthe error of ta includes ratio error and phase error. the measuring of the error of ta or the calibration o

11、f the accuracy of ta usually applies differential measuring method. the method needs a standard ta except the measured ta and a ta calibrator. there is the same turn ratio between the standard and measured t4 and the standard tas accuracy should be 2 levels higher than the measured one. the calibrat

12、or function lies in forming comparison circuits, measuring, and showing the error at all range. the comparison circuit, also referred to the difference measuring principle circuit, is showed in fig. 1. by measuring the voltage on i, and rd, calculate the corresponding current. then the calibrator ca

13、n indicate the error.when a ta has the same turn ratio between the primary and secondary winding, the self-comparison circuit could be used and is shown in fig.2. in the figures, ta0 and tax are standard and ta being measured respectively. np and ns are primary and secondary winding turns. ip and io

14、, id, i, are primary current secondary standard current, secondary error current, secondary current of ta being measured respectively. ro and r,r, are secondary windings resistance of standard ta, error current detecting resistance, burden resistance of ta being measured respectively. to and k, tb.

15、t, are voltage sampling points which can calculate the current in this paper, only voltage between k and t, voltage between tb and t, are being measured and they represent the voltage on r, and r, respectively.in general, the ta calibrators principle of the sample resistance should be: 1） it can not

16、 affect the accuracy of the comparison circuit. in the ideal condition r, and rd should be 0, but it can not be sampled. so there must be sample resistance, in this paper, r, as shown in fig, is used; 1） the magnitude of the sample resistance should make the sampled standard current and error curren

17、t in pro rata and should not have too much difference. the sampled resistance is set by experiment: r, is the secondary standard current sampling resistance and can be 0.1-0.50, r, is the error current sampling resistance and can be, r, is the burden resistance and it depends on the ta being measure

18、d. e$ sampling the voltage uo and u, on r, and r, respectively, the ratio error and phase error are showed on the led through some process and calculations.according to the ta errors phase diagram, when io is maximum, the value of id is the ratio error; when io changes from negative to positive and

19、equals to 0, the value of id is the phase error. for the same principle, the relationship is equal to the voltage signal u, and ud. showed in fig.3. a and b is represent the ratio error and phase error separately. the tas real ratio error c and phase error 6 can be found out through proper calculati

20、on,where u, is the amplitude of uo the t.4 calibrator doesnt need very high accuracy. 1% to 3% error for the calibrator is enough. because of the difference measuring principle, the error is the read error of calibrator, that is, the tas errors error being measured. but the calibrator needs to have

21、a suitable enlargement factor. the calibrator maximum enlargement factor through all channels should be 1000 times.iii. the principle of virtual ca libratorthe virtual instrument consists of three parts: the external comparison circuit (showed in fig.1 or fig.2), data acquisition card (pci-6023) ins

22、talled in the pc and the vi program by labview then, after the two channels signal u, and ud come into the pc through the adc, the rest of the work is done by the software. in this paper we use voltage u, on r, substitute for u, approximatively. the virtual calibrators work flow chart is shown as fo

23、llow: 1) set the essential initial values of the virtual calibrator; 2) press the start button to start to work, adjusting the voltage regulator and changing the primary current, let the ratio between primary current and the rated current change from 10% to 120%; 3) the vi program will group the vol

24、tage signal u, and ud , then use the digital filter to eliminate the harmonic:4) calculate the root-mean-square (rms) value of tlx and 14, find out the amplitude of 21; 5) calculate the rms valve of io (substitute for f, ), i, and the ratio between io and its rated current and show the results. 6) f

25、ind out the a and b showed in fig. 3, calculate the ratio error and phase error and show the results. 7) set the l times loop, record and show the errors acquired by every time, 8) show and print all the results of calibration. 9）stop. the front panel of the virtual calibrator has the controls, indi

26、ctor and switch. the function of controls is to set the initial value before it works, the function of the indictor is to show at1 kinds of needed values, including digital, curve and diagram etc. the switch decides the start and stop of the virtual calibrator. of course, to change the measuring ran

27、ge, the operator needs to adjust the voltage regulator and change the primary current. this operation is necessary like that of the traditional calibration, but the recording for the error in any range is done by the virtual calibration. this confirms the accuracy of recording and relieves the opera

28、tors work. the use of virtual calibrator is most interesting. the controls of virtual calibrator include:1) setting the two sampling (analogue input) channels; 2) setting the magnitude of sampling resistance in the comparison circuit; 3) setting the secondary rated current of measured ta; 4) setting

29、 the number of sampling of error curve; the indictor of virtual calibrator has:1) showing ratio and phase error, ratio between the primary current and the rated ones in digital; 2) showing ratio and phase error, ratio between the primary) current and the rated ones in curves and diagram, where the c

30、urve include the active sampling points and function fitting curves; 3) showing the error for the ratio between the primary current and the rated current from 10% to 1 20%;4) showing the waveform of standard and error current, digital value of amplitude; 5) showing of digita1 rms value the standard

31、and error current;6) showing the pole of ta in the comparison circuit;the above shows that the function of virtual calibrator is greatly expended that of the traditional ones. 7111s kind of calibrator is not only convenient to use, but also makes the performance of the calibrator much better. from t

32、he function that shows the waveform, we can find out if there are some harmonics in the current, and confirm the accuracy for the calibrator.iv. experimentthe virtual calibrator is mainly characterized by the flexibility compared with the traditional ones. although the front panel has many functions

33、, they can be easily extended by the user. so the virtual calibrator is of important value for the non-standard ta calibration.in the experiment, the primary current produce by a step-up current transformer and its current controlled by a voltage regulator. through fitting the comparison circuit, th

34、e measuring range of the virtual calibrator can be set in any value. this paper gives sa and 0.1a two kinds of tas calibration experiment. the parameter and method, results are presented below.a. 5a ta experiment the parameter of ta being measured is:because of the 1:1 ratio of turn, the calibration

35、 for it doesnt need standard ta. the calibration circuit show in fig2 we can apply self calibration method to measure its accuracy. the results are presented in the ftg.4 and fig5 and show that this tas accuracy can be defined as 0.5 degree.b. 0.1a ta experiment the parameter of standard ta: from th

36、e fig4 and 5, the accuracy of the ta being measured can be defined as 0.5 degree. in the experiment, the input signal of virtual calibrator should be properly grounded to avoid the disturbance. the sampling resistance in the comparison circuit should use precise ones and with no induction.v. conclus

37、ionsthe vi technique is one of the new scientific and technique productions. the appearance of vi is called“revolution of measuring and control technology”. according to the development of the software and hardware for computers, the vi thn01ogy will have more developing space. the vis will replace

38、most of the traditional ones in the 21th century. with its flexibility, the virtual calibrator can measure any kind of t.4 including standard and non-standard ones. but the traditional calibrator can not measure most of the non-standard ta. it can record and save, display the data automatically. the

39、 method presented in this paper gives a new way to make he ta calibration. the main characteristics of the virtual calibrator are: 1) flexibility, virtual calibrator is mainly made of labview software and can be easily modified by rewrite some software; 2.) multi function, vi is designed on pc. it h

40、as waveform indictor, parameter controls and so on. at the time we calibrating a tks accuracy, these functions can indicate many information such as waveform quality and so on; 3) convenience to carry and use; 4) high efficiency and accuracy.; 5) high ratio between performance and cost;6) for multip

41、le use in one pc. 7) it can record and save, display the calibration data automatically.基于labview的電流互感器校驗(yàn)儀xin ai hai bao t. h. song-布魯塞爾大學(xué)摘要虛擬儀器（vi），指的是利用軟件在計(jì)算機(jī)上建立各種各樣的儀器，比如說labview，就象是真的建立在計(jì)算機(jī)上的儀器一樣。其主要特點(diǎn)是多功能的，可以集成多種功能于一臺(tái)pc上，從而使其性能高，成本底。在我所講的這一章中，labview虛擬儀器技術(shù)應(yīng)用于測(cè)試與測(cè)量儀器電流互感器（at）。利用labview測(cè)量儀器電流互感器精

42、度校準(zhǔn)精度是相當(dāng)高的。這個(gè)虛擬的電流互感器校驗(yàn)儀不僅能夠自動(dòng)的進(jìn)行尺寸計(jì)算，而且還能夠指出錯(cuò)誤的狀態(tài)曲線。關(guān)于基于labview的電流互感器校驗(yàn)儀的測(cè)試表明，它不僅能夠用于替代傳統(tǒng)的校驗(yàn)儀，而且還能夠比傳統(tǒng)的檢驗(yàn)儀做的更好。關(guān)鍵字：電流互感器（at） at校驗(yàn)儀 虛擬儀器 labview i. 簡介 自從1992年美國建立vxibus rw.1.1標(biāo)準(zhǔn)以及national instruments公司出品labview軟件以后，虛擬儀器已經(jīng)為他們商業(yè)上奠定了基礎(chǔ)，虛擬儀器扮演的主要角色就是利用軟件來構(gòu)建各種儀器。大多數(shù)的傳統(tǒng)的儀器都能夠通過虛擬儀器來實(shí)現(xiàn)，虛擬儀器的通過pc來實(shí)現(xiàn)的真實(shí)可用的儀器

43、。 虛擬的電流互感器被廣泛的應(yīng)用于各種各樣的電流測(cè)量，并且它還具有保護(hù)功能，能隔離和擴(kuò)大測(cè)量范圍。隨著業(yè)務(wù)的快速發(fā)展計(jì)算機(jī)測(cè)量與控制技術(shù)， 與相繼出現(xiàn)的電流互感器和transduczr ，有越來越多的高accuracv和低secondarly 電流的電流變壓器。電流變壓器的標(biāo)準(zhǔn)電流通常是1a或者5a，而一些不標(biāo)準(zhǔn)的電流變壓器有可能是0.1a或者更底。雖然我們有技術(shù)，使這種校驗(yàn)方式硬件如單片計(jì)算機(jī)和電子電路，dsp等集成電路，但是這將耗資太大錢，為這些不符合標(biāo)準(zhǔn)的校準(zhǔn)器，并會(huì)采取過多的時(shí)間來校準(zhǔn)所作出的這些硬件，這樣不理想，所以無論從功能性和實(shí)用性都要求設(shè)計(jì)各種新的電流變壓器（at）。 該校驗(yàn)儀

44、表示，采用虛擬儀器技術(shù)，不僅能符合傳統(tǒng)要求的之一，而且還能滿足客戶要求的多功能，方便等優(yōu)點(diǎn)，并且還具有很高比例性能和成本。實(shí)驗(yàn)結(jié)果指出，虛擬的校準(zhǔn)儀可以為電流互感器提供比較好的測(cè)量和設(shè)計(jì)條件。虛擬儀器技術(shù)和個(gè)人計(jì)算機(jī)將被廣泛的應(yīng)用于電流互感器的校準(zhǔn)儀領(lǐng)域。.電流互感器校準(zhǔn)儀的工作原理 電流互感器的錯(cuò)誤包括比率誤差和相位誤差。電流互感器的測(cè)量誤差和校準(zhǔn)準(zhǔn)確性通常適用于微分測(cè)量方法。該測(cè)量方法除了實(shí)測(cè)ta和校驗(yàn)ta之外，還需要一個(gè)標(biāo)準(zhǔn)的ta。標(biāo)準(zhǔn)的ta和實(shí)測(cè)的ta之間必須有一個(gè)相同的空白比例，并且標(biāo)準(zhǔn)ta的的準(zhǔn)確性應(yīng)該比實(shí)測(cè)的ta高兩個(gè)等級(jí)。該校驗(yàn)功能應(yīng)該是形成比較電路，量度及顯示誤差在所有范圍內(nèi)

45、。比較電路，提及了不同的測(cè)量原理電路，如圖（1）所示。通過測(cè)量流過r0和rd的電流,并且計(jì)算出其他的相應(yīng)電流，那么校準(zhǔn)儀就可以顯示誤差了。 當(dāng)ta的主繞阻和次繞組之間有一個(gè)相同的變換比例的時(shí)候，自我對(duì)比電路將開始工作，如圖（2）所示。ta0和tax是標(biāo)準(zhǔn)的并且ta是分開測(cè)量的。np和ns分別是主次繞組的匝數(shù)。 ip,io,id,ix分別是初級(jí)電流，二級(jí)標(biāo)準(zhǔn)電流，二次誤差電流以及ta的二次被測(cè)電流。r0,rd,rb分別是ta的標(biāo)準(zhǔn)二次繞組電阻，誤差電流檢測(cè)電阻，被獨(dú)立測(cè)量的工作電阻。t0，k，tx,tb 是數(shù)據(jù)采樣點(diǎn)的計(jì)算電流。在我將的這一章中，只有k和tx之間的電壓，tb和tx之間的測(cè)量電壓，

46、以及它們分別回饋到rd和rb 上的電壓。 圖（2）ta反饋帶電路示意圖總體來說，ta的工作原理以及其采樣電阻應(yīng)該是：1）它不能夠影響比較電路的準(zhǔn)確性，在理想的情況下，r0和rd應(yīng)該為0，并且他們都不能夠被采樣，因此，必須確定采樣電阻，在本文中rd被用于采樣電阻；2）規(guī)模樣本阻力應(yīng)使采樣標(biāo)準(zhǔn)電流與誤差電流分配，不應(yīng)該相差太大，采樣電阻是有實(shí)驗(yàn)來確定的：r0是次要標(biāo)準(zhǔn)電流采樣阻，電阻可0.1-0.5 ，rd是誤差采樣電阻，電阻可在10-100，rb是負(fù)載電阻，他由ta來決定的。同理，r0和rd上的電壓u0和ud，就會(huì)通過一些計(jì)算方法和過程在顯示器上顯示出比例誤差和相位誤差。 根據(jù)ta的誤差相位圖9

47、，當(dāng)i0最大時(shí)，相應(yīng)的id就是比例誤差，當(dāng)i0從負(fù)到正變化并逐漸接近0的時(shí)候，id的值就是相位誤差。同理，u0和ud的關(guān)系是對(duì)等的，如圖（3）所示，a和b是代表比誤差和相位誤差分別。則ta的真實(shí)的比例誤差f和相位誤差就可以通過計(jì)算得出。其中u0m是u0的振幅。ta校準(zhǔn)儀的精度不需要很高，0.1%到3%已經(jīng)足夠了。由于測(cè)量原理的不同，誤差在于讀數(shù)的誤差，也就是說，ta的誤差的誤差測(cè)量。但是校驗(yàn)需要一個(gè)合適的擴(kuò)張系數(shù)，該校準(zhǔn)器最多擴(kuò)張系數(shù)必須各個(gè)通路應(yīng)為1000 倍。iii.虛擬校準(zhǔn)儀的原則 虛擬儀器包括三部分：外圍電路比較（如圖1圖2），數(shù)據(jù)采集卡（pci-6023）以及通過labview安裝的

48、個(gè)人計(jì)算機(jī)上的程序。然后，在兩個(gè)頻道的信號(hào)u0和ud來進(jìn)入計(jì)算機(jī)，通過轉(zhuǎn)換器，其余的工作是由軟件.在這篇文章中，我們使用rb上的電壓ux來代替u0。那么虛擬校驗(yàn)儀的工作流程如下：1）設(shè)置虛擬校驗(yàn)儀的必要的初始值。2）按下啟動(dòng)按鈕，開始工作，調(diào)整電壓調(diào)節(jié)和改變初級(jí)電流， 讓初級(jí)電流及額定電流的比率由10 至120 變化。3）虛擬校準(zhǔn)儀將連接獨(dú)立的電壓ux和ud然后使用數(shù)字濾波器，以消除諧波。4）計(jì)算ux和ud的均方值，找出u0的振幅。5）計(jì)算出i0的均方值，id和i0的額定電流以及比例關(guān)系，并顯示結(jié)果。6）找出如圖3中a和b，計(jì)算比誤差和相位誤差，并顯示結(jié)果。7）設(shè)定k倍環(huán)路，記錄并顯示每次錯(cuò)誤。8）顯示和打印所有的校準(zhǔn)結(jié)果。9）停止。 虛擬校準(zhǔn)的前面板上有管制，指標(biāo)和開關(guān)三個(gè)按紐