基于LabVIEW的電流互感器校驗儀翻譯

1、畢業(yè)設(shè)計外文翻譯 題目： 交通燈控制系統(tǒng) 學 院： 信 息 與 電 子 工 程 學 院 專 業(yè)： 測 控 技 術(shù) 與 儀 器 班 級： 測 儀 0 6 0 1 學 號： 0611400133 學生姓名: 蔡碎斌 指導教師： 余金華 二O一O年四月外文翻譯之一A LabVIEW Based Instrument Current Transformer CalibratorXin Ai Hai Bao Y.H Song(1) North China Electric Power University, Beijing, China 102206 (2) Brunel University. UKA

2、BSTRACTThe Virtual Instrument (VI) mainly refers to build all kinds of instruments by software such as LabVIEW, which likes a real instrument build in a computer. Its' main characteristics are flexibility, multi-functions, multiple uses for one PC computer, giving high performance, and is less c

3、ostly. In this paper, the VI technology is applied to the test and measurement of instrument current transformer (TA). By using the LabVIEW, the TA accuracy calibrator was developed. This virtual TA calibrator can automatically measure the accuracy of TA and can indicate the ratio error and phase er

4、ror curves. The tests and calibration for the TA show that the virtual TA calibrator can be used in place of the traditional calibrator and is much better than the traditional one. Keywords:Instrumentcurrenttransformer(TA),TAcalibrator,VirtualInstruments,LabVIEW. INTRODUCTIONSince 1992 the VXIbus Re

5、w.1.4 standard wasestablished by the United States and LabVIEW was presented by the National Instruments co.(NI), the Virtual 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 traditiona

6、l instrument can be developed by VI. The VI is a real instrument made by the personal computer. 1 The Instrument current transformer (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

7、 of computer measurement and control technology, and with the sequent emergence of current transformer and transduczr, there is an increasing number of current transformers with high accuracv and low secondarly current. The standard TA secondary current is usually 1A or 5A，some non-standard TA secon

8、dary current may be 0.1A or lower 2 3 . Although we have the technique to make this kind of calibrator by means of hardware such as single chip computer and electronic circuit, DSP and so on4-8, it will cost too much money for these no-standard calibrator and will take too much time and the calibrat

9、or made by these hardware mill not be satisfactory in both function and practicality for designing all kinds of new TA.The calibrator 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, convenienc

10、e, and high ratio between performance and cost. The experiment results indicate that the virtual calibrator can provide excelIent condition for TA measurement and design. The VI technolog and personal computer must be widely used in the area of calibration on instrument transformer. THE WORNNG PRINC

11、IPLE OF TA CALIBRATORThe error of TA includes ratio error and phase error.The measuring of the error of TA or the calibration of 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 tum ratio be

12、tween the standard and measured TA and the standard TA's accuracy should be 2 levels higher than the measured one. The calibrator function lies in forming comparison circuits, measuring, and showing the error at all range. The comparison circuit,also referred to the difi-erence measuring princip

13、le circuit, is showed in Fig. 1. By measuring the voltage on R0 and Rd , calculate the corresponding current.Then the calibrator can indicate the errors.Fig.1 Schematic of TA comparison circuitWhen a TA has the same turn ratio between the primary and secondary winding, the self-comparison circuit co

14、uld 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, id , ix, are primary current.secondary standard current, secondary error current,secondary current of TA being measured respec

15、tively.Ro and Rd, Rb, are secondary winding's resistance of standard TA. error current detecting resistance,burden resistance of TA being measured respectively.To and K, Tb. Tx, are voltage sampling points which can calculate the current In this paper, only voltage between K and Tx, voltage betw

16、een Tb and Tx, are being measured and they represent the voltage on Rd, and Rb, respectively.Fig.2 Schematic of TA self-comparison circuitIn general, the TA calibrator's principle of the sample resistance should be: 1) it can not affect the accuracy of the comparison circuit. In the ideal condit

17、ion Ro, and Rd should be 0, but it can not be sampled. So there must be sample resistance, in this paper, Rd, as shown in Fig.2, is used; 2) the magnitude of the sample resistance should make the sampled standard current and error current in prorata and should not have too much difference. The sampl

18、ed resistance is set by experiment: Ro, is the secondary standard current sampling resistance and can be 0.1-0.5, R4, is the error current sampling resistance and can be lO-lOOQ,R, is the burden resistance and it depends on the TA being measured. By sampllng the voltage Uo and Ud, on R0 and Rd, resp

19、ectively, the ratio error and phase error are showed on the LED through some process and calculations.According to the TA error's phase diagram 9, when io is maximum, the value of id is the ratio error,when io changes from negative to positive and equals to 0, the value of id is the phase error.

20、 For the same principle, the relationship is equal to the voltage signal U0, and Ud . showed in Fig.3. a and b is represent the ratio error and phase error separately. the TA's real ratio error f and phase error can be found out through proper calculation,where Uom is the amplitude of Uo.The TA

21、calibrator doesn't 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 TA's error's error being measured. But the calibrator needs to have a suitable enlargement facto

22、r. The calibrator maximum enlargement factor through all channels should be 1000 times l0ll.Fig3 The Sketch map or ratio and phase error.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 acquisitio

23、n card (PCI-6023) installed in the PC and the VI program by LabVIEU! Then, after the two channels' signal U0, 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 Ur, on Rb,substitute for U0, approxhatively. The virtual calibrator

24、9;s work flow chart is shown as follow: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

25、VI program will group the voltage signal U,and ud , then use the digital filter to eliminate the harmonic:4) Calculate the root-mean-square (RMS) value of uand Ud, find out the amplitude of u0, ;5) Calculate the RMS valve of io (substitute for i, ),id, and the ratio between io and it's rated cur

26、rentand show the results.6) Find out the a and b showed in Fig. 3, calculate the ratio error and phase error and show the resuits.7) Set the k 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 calibr

27、ator has the Conrrols,hdictor and Switch. The function of Controls is to set the initial value before it works, Tne 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 oithe virtual calibrator.Of cours

28、e, to change the measuring range, the operator needs to adjust the voltage regulator and change the primary current. This operation is necessary lke 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 reco

29、rding and relieves the operator's work. The use of virtual calibrator is most interesting. The controIs of virtuaf 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 cur

30、rent of measured TA;4) Setting the number of sampling of error curve;The Indictor of virtual calibrator has:1) Showing ratio and phase error, ratio between theprmary current and the rated ones in digital;2 ) Showing ratio and phase error, rdtio between the prmary current and the rated ones In curves

31、 and diagram. where the curve include the active sampling points and function fitting curves.3) Showing the error for the ratio between the primary currcnf and the rated current from 1 O?G to 120°%.4) Showing the waveform of standard and error current,digital value of amplitude;5 )Showing of di

32、gita1 RMS value the standard 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. This kind of calibrator is not only convenient to use, but also makes the performance of the ca

33、librator much better.From the 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 fro

34、nt panel has many functions. 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 voltagc regulator. Through fi

35、tting the comparison circuit, the measuring range of the virtual calibrator can be set in any value. This paper gives SA and 0.1A two kinds of TXs calibration experiment. The parameter and method. results are presented below.A. 5A TA experimentThe parameter of TA being measured is:Ratio of turn: Np

36、： Ns=100：100;Ratio of current:Ip ：Is=5A：5AWindlng resistance 0.1Core size: 70x1 1Ox4O(mm).Core material: silicon-steel sheet;Burden: Rb =1 , cos =l.Because of the 1:1 ratio of turn, the calibration for it doesn't need standard TA. The calibration circuit show in Fig2 We can apply self calibratio

37、n method to measure it's accuracy. The results are presented in the Ftg.4 and Fig.5 and show that this TA's accuracy can be defined as 0.5 degree.B. 0.1 A TA experimentThe parameter of standard TA: Ratio of turns: 1:1000;Ratio of currant: Ip ：Is = 100A: 100mA:Secondary winding resistance 8 .

38、5;Core size 29 x 46 x 25(mm);Core material: permalloy;Accuracy 0.01 degree;The parameter of TA being measured is:Ratio of turn Np ： Ns =1 :1OO0;Ratio of current: Ip ：Is =100A:100mA;Secondary winding resistance. 3O;Core size: 2Ox40x15(mm):Core material: silicon-steel sheet;Burden: Rb =35, cos =l From

39、 the 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 hsturbance. The sampling resistance in the comparison circuit should use precise ones and with no induction.Fig.4 ra

40、tio error curvesFig.5 phase error curvesV. CONCLUSIONSThe 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 h

41、ave more developing space. The VIS will replace 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 recor

42、d and save,display the data automatically. The 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)

43、Multi function, VI is designed on PC. It has 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 betwe

44、en performance and cost;6 )For multiple use in one PC.7)It can record and save, display the calibration data automatically.VI. REFERENCE1 LabVlEW Data Acquisition Basics Manual, Nabonal Instruments Co. of USA., 19982 Xm XI, Hai Bao, Yonghua Song, Novel method of Eror Current Compensation for Hall Ef

45、fect Based HighAccuracy Current Transformer, IEEE Transactions on Instrument and Measurement, 2003 (adopted)3 AI Xin, Hao Yushan. Yang Yihan et al, CT Calibrator Based on virtual Instruments, Beijing: Clunese Joumal of Scientific Instrument,V 01.2 1I No.4, Aug.2000,p p331 -3344 Carney, A.C.; Simple

46、absolute method for current transformer calibration, IEEE Transactions onInstrumentation and Measurement, Vo1.50 Issue: 2, April 2001, pp278 -2815 Lap& R.; Svetik, Z.; Current transformet calibration using synchronous sampling, Digest of Conference on Precision Electromagnebc Measlrrements, 16-2

47、 I June 2002, pp548-5496 Comey: A.C.; A simple traceable current transformer calibration method,Digest of Conference on Precision Electromagnetic Measurements, 14-19 May 2000, pp6607 Waltrip, B.C; Nelson T.L.; A system to measure current transducer performance. Digest of Conference on Precision Elec

48、nomagnetic Measurements, 6-1 0 July 1998, pp272-2738 Zoltan, I.; A new self-calibrating standard instrument for current transformer calibration, Digest of Conference on Precision Electromagnetx Measurements. 27 June- 1998 ;pp238 -2399 HES-IS type dgital transformer calibrator rhrection, Jiang Su Jin

49、g Jiang Measuring instrument factmy, 199710 Zhao Xiumin Current Transformer, Tai yuan: San Xi Scientific and Education Press, l990(In Chnese)11 Zhao Xiumin, Transformer Calibrator, Tai yuan: San Xi Scientific and Education Press, 1996 (In Chnese)中文譯文一基于LabVIEW的電流互感器校驗儀Xin Ai Hai Bao Y.H.Song(1)華北電力大

50、學學報,北京,中國107206 (2)布魯內(nèi)爾大學。英國(3)摘自互聯(lián)網(wǎng)，網(wǎng)址： /iel5/9986/32068/01492139.pdf?tp=&arnumber=1492139&isnumber=32068摘要：虛擬儀器（VI），指的是利用軟件在計算機上建立各種各樣的儀器，比如說Labview，就象是真的建立在計算機上的儀器一樣。其主要特點是靈活多功能的，可以集成多種功能于一臺PC上，從而使其性能高，成本卻底。在我所講的這一章中，Labview虛擬儀器技術(shù)應用于測試與測量儀器電流互感器（TA）。利用Labview測

51、量儀器，電流互感器精度校準的精度是相當高的。這個虛擬的電流互感器校驗儀不僅能夠自動的進行尺寸計算，而且還能夠指出錯誤的狀態(tài)曲線?；贚abview的電流互感器校驗儀的測試表明，它不僅能夠用于替代傳統(tǒng)的校驗儀，而且還能夠比傳統(tǒng)的檢驗儀做的更好。關(guān)鍵字：電流互感器（TA）,TA校驗儀,虛擬儀器 Labview I.簡介自從1992年美國建立VXIbus Rew.1.4標準以及National Instruments公司出品Labview軟件以后，虛擬儀器就已經(jīng)為他們商業(yè)上奠定了基礎(chǔ)，它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現(xiàn)。虛擬儀器是通過PC來實現(xiàn)的真

52、實可用的儀器。虛擬的電流互感器被廣泛的應用于各種各樣的電流測量，并且它還具有保護功能，能隔離和擴大測量范圍。隨著業(yè)務(wù)的快速發(fā)展計算機測量、控制技術(shù)和相繼出現(xiàn)的電流互感器和傳感器，有越來越多的高準確性和低二次電流的電流變壓器。電流變壓器的標準電流通常是1A或者5A，而一些不標準的電流變壓器有可能是0.1A或者更底。雖然我們有技術(shù)，使這種校驗方式硬件如單片計算機和電子電路，DSP等集成電路，但是這將耗資太大錢，為這些不符合標準的校準器，并會采取過多的時間來校準所作出的這些硬件，這樣不理想，所以無論從功能性和實用性都要求設(shè)計各種新的電流變壓器（TA）。 該校驗儀表示，采用虛擬儀器技術(shù)，不僅有符合傳統(tǒng)

53、要求，而且具有滿足客戶多功能要求、方便等優(yōu)點，并且還具有很高比例性能和成本。實驗結(jié)果指出，虛擬的校準儀可以為電流互感器提供比較好的測量和設(shè)計條件。虛擬儀器技術(shù)和個人計算機將被廣泛的應用于電流互感器的校準儀領(lǐng)域。.電流互感器校準儀的工作原理電流互感器的錯誤包括比率誤差和相位誤差。電流互感器的測量誤差和校準準確性通常適用于微分測量方法。該測量方法除了實測TA和校驗TA之外，還需要一個標準的TA。標準的TA和實測的TA之間必須有一個相同的空白比例，并且標準TA的的準確性應該比實測的TA高兩個等級。該校驗功能應該是形成比較電路，量度及顯示誤差在所有范圍內(nèi)。比較電路， 圖（1）比較原理路 提及了不同的測

54、量原理電路，如圖（1）所示。通過測量流過R0和Rd的電流,并且計算出其他的相應電流，那么校準儀就可以顯示誤差了。當TA的主繞阻和次繞組之間有一個相同的變換比例的時候，自我對比電路將開始工作，如圖（2）所示。TA0和Tax是標準的并且TA是分開測量的。Np和Ns分別是主次繞組的匝數(shù)。 ip,io,id,ix分別是初級電流，二級標準電流，二次誤差電流以及TA的二次被測電流。R0,Rd,Rb分別是TA的標準二次繞組電阻，誤差電流檢測電阻，被獨立測量的工作電阻。T0，K，Tx,Tb 是數(shù)據(jù)采樣點的計算電流。在我將的這一章中，只有K和Tx之間的電壓，Tb和Tx之間的測量電壓，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該是：（1）：它不能夠影響比較電路的準確性，在理想的情況下，R0和Rd應該為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)模樣本阻力應使采樣標準電流與誤差電流分配，不應該相差太大，采樣電阻是有實驗來確定的：R0是次要標準電流采樣阻，電阻可0.1-0.5 ，Rd是誤差采樣電阻，電阻可在10-100，Rb是負載電阻，他由TA來決定的。同理，R0和Rd上的電壓u0和ud，就會通過一些計算方法和過程在顯示