畢業(yè)設(shè)計(jì)英文翻譯使用電超聲波技術(shù)檢測(cè)變壓器局部放電

1、 譯 文原文題目：transformer partial discharg detection using electrical-ultrasonic technology 譯文題目: 使用電超聲波技術(shù) 檢測(cè)變壓器局部放電 學(xué) 院: 電子信息學(xué)院 專業(yè)班級(jí): 電氣工程及其自動(dòng)化2009級(jí)7班 學(xué)生姓名: 李龍龍 學(xué) 號(hào): 20903040702 transformer partial discharge detection usingelectrical-ultrasonic technologywei jiang, fan liu, zhiyuan wangsichuan electric

2、power research institutechengdu, chinaabstractpartial discharge (pd) is usually happened caused by flaw and deterioration of transformer insulation. it is the main reason of the accident of transformer and power system. therefore, it's necessary and important to detect the partial discharge of t

3、ransformer while operating and manufacturing. when pd of transformer internal insulation occurs, electromagnetic waves, sound waves and other signals are produced. according to supersonic signal, we can detect the location of pd. but this method can not test the number of charge. with electrical-ult

4、rasonic detection method, it is easy to locate pd and test the number of charge. in this paper, a method of electrical-ultrasonic detection is presented, which is based three-dimensional scatter point and ultrasonic hit to time. the method is effective to locate fault of transformer insulation. to v

5、alidate the approach, a case is introduced.keywordspartial discharge; electrical-supersonic detection method; pulse current method; power transformer. introductionpartial discharge is common on account of flaw and deterioration of insulation, especially in power transformer, and is the main reason o

6、f the accident of transformer and power system. therefore, it's necessary and important to detect the partial discharge of transformer while operating and manufacturing. when pd of transformer internal insulation happen, electromagnetic waves, sound waves and other signals are produced at the sa

7、me time. though detect the ultrasonic signal, we can locate the pd1-3. pd detection using ultrasonic signal can locate the discharge, but this method can not test the number of the discharge. partial discharge test can effectively test the discharge, but can not accurate locate 4-6. if we use pd ult

8、rasonic location and partial discharge test at the same time, the number and location of discharge can be tested. we call this method is electical-ultrasonic technology 7-10. a method of electical-ultrasonic detection is presented in this paper, which is based three-dimensional scatter point and sup

9、ersonic hit to time. with a case, the accuracy of pd electical-ultrasonic detection method is demonstrated. transformer pd electical-ultrasonic detection principlewhen partial discharge of transformer internal isolation occurs, the ultrasonic signal will form spherical wave and spread to the surroun

10、ding with 1400m / s speed in the transformer oil. as long as placed ultrasonic sensors on the outside of transformer tank wall, ultrasound produced by pd can receive. we can locate the discharge of by detecting ultrasonic signal. but it hard to test the number of the discharge only by ultrasonic sig

11、nal. partial discharge test based on pulse current method can not accurate locate discharge source, though it can effectively test the discharge. so, electrical-ultrasonic, that detect both ultrasonic signal and pulse current discharge, can realize to test the number and location of discharge. the d

12、etection principle in figure 1.fig.1 transformer pd electical-ultrasonic detection principlea. partial discharge ultrasonic locationpd ultrasound location method is that placing ultrasonic sensors on a few points of the transformer tank shell, composed of acoustic array to measure the spread time or

13、 relative time of each sensor, then according to the time to solve equations of pd source location.fig.2 transformer pd ultrasonic detection principlewe can see from fig.2. set the coordinate of discharge source location is p（x,y,z）, the transformer length, width and height are m, n and h. there are

14、 six sensors on the transformer tank shell. their coordinates are （0,）, （,n,）, （,0,）, （m,）, （,0）, （,0）. so, the straight-line distance from the six sensors to pd source are:（1）（2）（3）（4）（5）（6）set， are the time difference between pd source to 、 and pd source to. set v is the ultrasonic speed. therefor

15、e（7）（8）（9）（10）（11）we can determine the locations of，.when we set the sensors on transformer tank shell. the time difference of can be between ，and can be measure by multi-channel oscilloscope. so, the location of pd source can be get by solve formula（1）（11）. because transformer internal structure is

16、 complex, which is compound of different materials, such as oil, copper, silicon steel and so on. ultrasound propagation path is not complete linear, but it is include some refraction. because the frequency of ultrasound is very high, refraction is very small. therefore, by ultrasound signal, we can

17、 accurately detect the location of partial discharge. more sensors we use, more accurate location we get.b. transformer partical didcharge test(1) test methodpartial discharge test using power supply of five times the frequency,250hz, apply test voltage in the transformer lowvoltage winding. a detec

18、tion impedance are connected to the final layer of tested casing insulating paper, then link to the pd test apparatus by data cable.to supplement the transformer capacitive current, some reactors are paralleled to the transformer low voltage side, where is applied test voltage. before the test, a sq

19、uare wave, with 500pc charge, are injected into the high (medium) voltage final layer of tested casing insulating paper to calibrated the number of discharge. setting pd test apparatus to adjust pd 100 meter gauge shows full-scale grid, which indicated 500pc discharge. transformer pd test principle

20、using pulse current method is shown in fig 3.fig.3 transformer pd test principle using pulse current method(2) test voltageset is the maximum operating voltage, is equal to and is equal to . turn on power supply in less than . up voltage to , maintained this voltage for 5 min, maintained it for 5 mi

21、n, and voltage to to and maintained 24 min. then down voltage to , maintained it at less for half hours and test the number of transformer pd. further reduced this voltage to , and maintained it for 5min.turn off power supply when it less than . in the entire period of test, partial discharge should

22、 be monitored.(3) test compensationtaking into account that the capacity of the frequency power supply unit and possible resonance, discharge-free reactors are used in the test to compensate capacitive current. according to the actual power capacity, the required reactive power compensation can be e

23、stimated by the following formula:（12）using the reactors to compensate for capacitive currents. during the voltage up to 20% and 50% , monitor compensation reactor and transformer current, and determine to increase or decrease the capacity of compensation reactor. example of electical-ultrasonic pd

24、detectionacetylene in oil of a 220kv substation #1 power transformer is excessive. follow-up examination found that acetylene is still excessive, and there is a trend to further increase. inner insulation of the transformer is likely to exist the phenomenon of partial discharge. to prevent transform

25、er failure，the power companion stop the transformer, evaluate its insulating state by the method of electical-ultrasonic detection and detect possible partial discharge location.a. ultrasonic partial discharge field testingduring partial discharge test, ultrasonic pd field testing is carry out with

26、disp 24-channel ultrasound pd detection system.(1) transformer modeling and sensor placementsetting the origin of coordinates is the bottom right corner along the tank of transformer high voltage side. we can see from fig.4. x-axis positive direction along the tank wall, the phase c direction toward

27、 the phase b. y-axis direction is up and perpendicular to the tank bottom. z axis is perpendicular to the tank wall from outside to inside. the length of tested transformer is 8.86m, its width is 2.75m and its high is 3.56m. set up the transformer geometric model as x = 8.86m, y =3.56m and z = 2.75m

28、.fig.4 transformer pd location coordinatesthe sensor r15i is used that have 18 channels, built-in ultrasonic pulse 40 db and preamplifier resonant frequency 150khz. there are six sensors placed on the positive and negative surface of the transformer, four sensors placed on the two sides transformer,

29、 and two sensors placed on the transformer bottom. after finishing sensor placement, the threedimensional model of the transformer is shown in figure 5.fig.5 the three-dimensional model of the transformer with sensors(2) parameter settingparameters setting of ultrasonic detection for transformer ins

30、ulation fault are threshold value, sound speed, sample rate, filter range and so on. set the amplitude of ultrasonic signal is 45db, and the float threshold value is 4db. as magnetic noise energy of transformer core concentrated in the 1065khz frequency range and transformer noise is focused on belo

31、w 15khz frequency band, the strongest frequency band in the vicinity of 1.5khz. the filter frequency analog filters lower limit is set to 1khz, upper limit is 400khz, and sampling rate is 1msps. set the velocity of ultrasonic signal is 1400m/s, the minimum impact is 4 and maximum impact is 8.accordi

32、ng to desired output, we can set hit to time, energy to time, amplitude to time, and three-dimensional scatter plot, etc. this test use multi-channel to show the plot of hit to time which facilitated analysis and comparison to locate the transformer insulation fault.(3) result of pd detectionit took

33、 6 hours to locate the transformer insulation fault. there are obvious sudden and high amplitude acoustic emission signal during the testing. the distribution of ultrasonic signal amplitude is a large range, and the most amplitude is 2810db. signals triggered frequently. some channels can always cap

34、ture the signal. ch1, ch2, ch7, ch8, ch13, ch14 signal have pd characteristics. these six-channel signal meet the ultrasonic signal characteristics. the ultrasonic signal amplitudes of ch7 and ch14 are greater, respectively 1892db and 2810db. therefore, we think that these six channels may be receiv

35、ed partial discharge signal and the corresponding discharge points concentrated in the near block comic high of transformer phase a.fig.7 scatter plot of transformer insulation fault locationfigure.7 shows that: discharge points focus on the channel 1,2,7,8,13,14 which is in accord with the results

36、of the sensor receiving. so, if there is partial discharge of transformer insulation, it should concentrate in the vicinity of comic high seat of transformer phase a. the number of partial discharge can be tested by partial discharge test carried out at the same time.b. transformer partial discharge

37、 testingwhen we have transformer insulation ultrasonic detect, carry out partial discharge testing at the same time to test the number of partial discharge. transformer main parameters: type: sfpsz7-120000/220rated voltage:（220±8×1.25%）/121/10.5 kvrated capacity: 120/120/60mvaconnection: d

38、11(1) test voltage calculationhv winding: power system maximum operating voltage: =252 kvtest voltage: =218 kvmv vinding: power system maximum operating voltage: =126 kvtest voltage: =109 kvhv winding: =139.4 kvmv vinding: =69.8 kvtest voltage times: k=1.56the test voltage of lv winding:=60.06 kvthe

39、 test voltage of mv winding:=（）×1.56=108.9 kv(2) compensation estimatesconsider the capacity of doubling frequency power and possible resonance, no-discharge reactor is use to compensate reactive power during the test. the capacitance is 16000pf to estimate the capacity compensating for the rea

40、ctive power.using the reactor to compensate. when the voltage is 20% and 50% of the , we monitor the currents of the compensating reactor and transformer. according to the size of these two currents to increase or decrease the compensation reactor capacity.(3) results of partial discharge testpartia

41、l discharge test of transformer phase a show that: when test voltage increased to 116kv (about ), the partial discharge reached 618pc and exceeded 500pc that is the amount of partial discharge limits provided by gb50150-2006 "installation of electrical installations-electrical equipment transfe

42、r testing standard".fig.8 the number of partial discharge at the number of partial discharge reached 5010pc, when test voltage increased to . discharge pulses were in the first and third quadrant and they were symmetric, which is the typical pd pattern, shown in fig.8. therefore, we can determi

43、ne that there is transformer insulation failure in phase a. combined with ultrasonic location, the location of partial discharge can be detected.c. rrsult of electical-ultrasonic detectionwith ultrasonic signals of transformer insulation fault received by each sensors, and three-dimensional scatter

44、plot of partial discharge point, we can see that there is partial discharge in the vicinity of comic high seat of transformer phase. according to partial discharge test done at the same time, we knew the number of transformer partial discharge is far exceeds the partial discharge limits in the natio

45、nal standard. electrical-ultrasonic can test the number and location of discharge. it good to prevent accidents caused by transformer insulation failure and to carry out repair work. conclusiona method of electical-ultrasonic detection is presented in this paper, which is effective to locate transfo

46、rmer insulation fault. a case is introduced to validate the accuracy of electical-ultrasonic detection. detecting ultrasonic signal produced by pd can locate the discharge, but this method can not test the number of discharge. partial discharge test can effectively test the discharge, but can not ac

47、curate locate. with electical-ultrasonic detection method, it is easy to locate pd and test the number of charge, which can effectively assess the status of transformer insulation.references1 xiaorong wang, bei wei, guanjun wang. a new partial discharge electrical location method of transformer wind

48、ing. high voltage technology. 1999,25(3): 27-292 bengtsson c. status and trends in transformer monitoring. ieee transaction on power delivery. 1996,11(3):1379-13843 tatsuo takada, acoustic and optical method for measuring electric charge distributions in dielectrics. ieee transactions on dielectrics

49、 and electrical insulation, 1999, 6(5):519-5474 caixin sun, wenqi zhao. electrical-acoustic and acoustic-acoustic locating method of transformer pd source and its evaluation study. transactions of china electrotechnical society. 1997,12(5): 49-52,605 h. g. kranz, a pd measuring and evaluation system

50、 based on digital signal processing. ieee transactions on dielectrics and electrical insulation, 2000, 7(1): 21-296 yang xu, ming yu, xiaolong cao, et al. partial discharge pulse measurements and comparison with the electrical measuring method. high voltage technology. 2001，27(4):3-47 t.boczar, iden

51、tification of specific type of pd from acoustic emission frequency spectra. ieee transactions on dielectrics and electrical insulation, 2001, 8(4):598-6068 barry h. ward a survey of new techniques in insulation monitoring of power transformers. ieee electrical insulation magazine, 2001，17(3):16-239

52、yanpeng hao, guoli wang, hengkun xie, et al. study on aging properties of stator insulation based on partial discharge and ultrasonic method. transactions of china electrotechnical society. 2002, 17,( 2):1-610 caixin sun, bing luo, wenlin zhao. study on ultrasonic high sensitivity sensor for transfo

53、rmer partial discharge source location. chinese journal of scientific instrument. 1997,18(5): 453-458使用電超聲波技術(shù)檢測(cè)變壓器局部放電wei jiang, fan liu, zhiyuan wangsichuan electric power research institutechengdu, china摘要：局部放電（pd）是通常由變壓器絕緣的缺陷和惡化引起。它是變壓器和電力系統(tǒng)事故的主要原因。因此，當(dāng)變壓器在運(yùn)行時(shí)，檢測(cè)變壓器局部放電是非常必要的和重要的。 當(dāng)變壓器內(nèi)部絕緣發(fā)生局部放電時(shí)

54、，會(huì)產(chǎn)生電磁波、聲波等信號(hào)。用電超聲波方法，很容易找到局部放電位置和電量。本文提出了一種基于三維散射點(diǎn)和超聲波沖擊時(shí)間的電超聲波檢測(cè)方法。下面用一個(gè)例子來驗(yàn)證這種方法。關(guān)鍵詞：局部放電 ，電超聲波檢測(cè)方法;脈沖電流法;電力變壓器1.引言由于絕緣缺陷和惡化，局部放電是常見現(xiàn)象,尤其是在電力變壓器中,是變壓器和電力系統(tǒng)事故發(fā)生的主要原因。因此，在操作和制造變壓器時(shí)，檢測(cè)局部放電是很有必要和重要的。當(dāng)變壓器內(nèi)部絕緣局部放電發(fā)生，電磁波，同時(shí)產(chǎn)生的聲波和其他信號(hào)。雖然超聲波檢測(cè)信號(hào)，我們可以找到局部放電。利用超聲波信號(hào)的局部放電檢測(cè)可以定位放電位置，但這種方法不能測(cè)試放電量。局部放電試驗(yàn)可以有效地檢測(cè)

55、放電量，但不能準(zhǔn)確定位局部放電。如果我們使用局部放電超聲定位的同時(shí)，使用局部放電試驗(yàn)，放電的位置和量數(shù)都可以測(cè)試。我們稱這種方法為電超聲波技術(shù)。本文提出了一種基于三維散射點(diǎn)和超聲波沖擊時(shí)間的電超聲波檢測(cè)方法，并用一個(gè)例子來證電超聲波技術(shù)檢測(cè)局部放電。2.變壓器局部放電超聲波檢測(cè)原理當(dāng)變壓器內(nèi)部絕緣局部放電發(fā)生時(shí)，超聲波信號(hào)將形成球面波，并以1400m/s的速度在變壓器油箱中傳播。只要把超聲波傳感器放在變壓器油箱壁外，就可以接受由局部放電產(chǎn)生的超聲波。我們可以通過檢測(cè)超聲波信號(hào)定位局部放電，但是僅用超聲波信號(hào)很難測(cè)試放電量，基于脈沖電流局部放電檢測(cè)方法不能準(zhǔn)確定位放電來源，但它能有效測(cè)試放電量。

56、所以，同時(shí)檢測(cè)超聲波信號(hào)和脈沖電流放電的電超聲波檢測(cè)技術(shù)，能夠檢測(cè)出放電位置和放電量。檢測(cè)原理如圖1所示。圖1變壓器局部放電的電超聲波檢測(cè)原理（1）超聲波定位局部放電局部放電超聲波定位法是在變壓器箱殼的幾個(gè)點(diǎn)上放置傳感器，組成聲陣列來測(cè)量每個(gè)傳感器的傳播時(shí)間和相對(duì)時(shí)間，然后根據(jù)時(shí)間來解方程中局部放電的位置。圖2變壓器局部放電超聲波檢測(cè)原理從圖2知，設(shè)放電源的坐標(biāo)位置為p（x,y,z）, 變壓器的長(zhǎng)、寬、高分別為m、n、h，變壓器箱殼上有六個(gè)傳感器，它們的坐標(biāo)分別為（0,）, （,n,）, （,0,）, （m,）, （,0）, （,0），因此它們距放電源的位置分別為：（1）（2）（3）（4）（5

57、）（6）設(shè)放電源傳播到、的時(shí)間分別為，v為超聲波速度。則（7）（8）（9） （10） （11）當(dāng)在變壓器箱殼上放置傳感器時(shí)，可決定、的位置，用多通道示波器測(cè)量和、的時(shí)間，因此，放電源的位置可由公式（1）（11）解出。因?yàn)樽儔浩鲀?nèi)部結(jié)構(gòu)很復(fù)雜,這是復(fù)合不同的材料,如石油、銅、硅鋼等等。超聲波傳播路徑不是完整的線性,但它是包括一些折射。因?yàn)槌暡ǖ念l率非常高,折射是非常小的。因此,通過超聲波信號(hào),我們可以精確地檢測(cè)到局部放電的位置。我們使用多個(gè)傳感器,更多我們得到準(zhǔn)確的位置。（2）變壓器局部放電測(cè)試測(cè)試方法局部放電測(cè)試用電源的五倍頻率250hz,施加試驗(yàn)電壓在變壓器的低壓繞組。檢測(cè)阻抗連接到測(cè)試的最后一層套管絕緣紙，然后鏈接到通過數(shù)據(jù)電纜測(cè)試儀。為了補(bǔ)充變壓器的容性電流，將一些電抗器并聯(lián)到變壓器低壓側(cè)，當(dāng)作測(cè)試電壓。在測(cè)試之前，將方波與500pc電荷充電，注入高（中）電壓最后一層殼體絕緣紙校準(zhǔn)放電的數(shù)目。設(shè)置局部放電測(cè)試儀器，調(diào)整局部放電1