毕业设计英文翻译使用电超声波技术检测变压器局部放电

1、西安工程大学毕业设计（译文） 译 文原文题目：transformer partial discharg detection using electrical-ultrasonic technology 译文题目: 使用电超声波技术 检测变压器局部放电 学 院: 电子信息学院 专业班级: 电气工程及其自动化2009级7班 学生姓名: 李龙龙 学 号: 20903040702 15transformer partial discharge detection usingelectrical-ultrasonic technologywei jiang, fan liu, zhiyuan wangs

2、ichuan electric 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 partia

3、l discharge of transformer 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. wit

4、h electrical-ultrasonic 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

5、insulation. to validate 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 t

6、he main reason of 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 pr

7、oduced at the same 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.

8、if we use pd ultrasonic 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 scatt

9、er point and supersonic 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 sprea

10、d to the surrounding 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 b

11、y ultrasonic signal. 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

12、discharge. the detection 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 th

13、e spread time or 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

14、and h. there are 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

15、 speed. therefore（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 inter

16、nal structure is 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 ultrasoun

17、d signal, we can 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

18、winding. a detection 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. befor

19、e the test, a square 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

20、 test principle 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, mainta

21、ined it for 5 min, 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

22、discharge should 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 compe

23、nsation can be estimated 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 electica

24、l-ultrasonic pd 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 p

25、revent transformer 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

26、 carry out with 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

27、direction toward 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 =3.5

28、6m and z = 2.75m.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 si

29、des transformer, 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

30、 transformer insulation 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

31、 focused on below 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 imp

32、act is 8.according 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

33、detectionit took 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 channel

34、s can always capture 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 channe

35、ls may be received 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 w

36、ith the results 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 p

37、artial discharge 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: 120/120/60

38、mvaconnection: d11(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 wind

39、ing:=60.06 kvthe 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 compensa

40、ting for the reactive 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 disc

41、harge testpartial 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 e

42、quipment transfer 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

43、, we can determine 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-dime

44、nsional scatter 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 lim

45、its in the national 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 t

46、o locate transformer 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

47、, but can not accurate 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

48、transformer winding. 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 transaction

49、s on dielectrics 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 e

50、valuation system 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):3-4

51、7 t.boczar, identification 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, 20

52、01，17(3):16-239 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 se

53、nsor for transformer partial discharge source location. chinese journal of scientific instrument. 1997,18(5): 453-458使用电超声波技术检测变压器局部放电wei jiang, fan liu, zhiyuan wangsichuan electric power research institutechengdu, china摘要：局部放电（pd）是通常由变压器绝缘的缺陷和恶化引起。它是变压器和电力系统事故的主要原因。因此，当变压器在运行时，检测变压器局部放电是非常必要的和重要的。

54、 当变压器内部绝缘发生局部放电时，会产生电磁波、声波等信号。用电超声波方法，很容易找到局部放电位置和电量。本文提出了一种基于三维散射点和超声波冲击时间的电超声波检测方法。下面用一个例子来验证这种方法。关键词：局部放电 ，电超声波检测方法;脉冲电流法;电力变压器1.引言由于绝缘缺陷和恶化，局部放电是常见现象,尤其是在电力变压器中,是变压器和电力系统事故发生的主要原因。因此，在操作和制造变压器时，检测局部放电是很有必要和重要的。当变压器内部绝缘局部放电发生，电磁波，同时产生的声波和其他信号。虽然超声波检测信号，我们可以找到局部放电。利用超声波信号的局部放电检测可以定位放电位置，但这种方法不能测试放

55、电量。局部放电试验可以有效地检测放电量，但不能准确定位局部放电。如果我们使用局部放电超声定位的同时，使用局部放电试验，放电的位置和量数都可以测试。我们称这种方法为电超声波技术。本文提出了一种基于三维散射点和超声波冲击时间的电超声波检测方法，并用一个例子来证电超声波技术检测局部放电。2.变压器局部放电超声波检测原理当变压器内部绝缘局部放电发生时，超声波信号将形成球面波，并以1400m/s的速度在变压器油箱中传播。只要把超声波传感器放在变压器油箱壁外，就可以接受由局部放电产生的超声波。我们可以通过检测超声波信号定位局部放电，但是仅用超声波信号很难测试放电量，基于脉冲电流局部放电检测方法不能准确定位

56、放电来源，但它能有效测试放电量。所以，同时检测超声波信号和脉冲电流放电的电超声波检测技术，能够检测出放电位置和放电量。检测原理如图1所示。图1变压器局部放电的电超声波检测原理（1）超声波定位局部放电局部放电超声波定位法是在变压器箱壳的几个点上放置传感器，组成声阵列来测量每个传感器的传播时间和相对时间，然后根据时间来解方程中局部放电的位置。图2变压器局部放电超声波检测原理从图2知，设放电源的坐标位置为p（x,y,z）, 变压器的长、宽、高分别为m、n、h，变压器箱壳上有六个传感器，它们的坐标分别为（0,）, （,n,）, （,0,）, （m,）, （,0）, （,0），因此它们距放电源的位置分别

57、为：（1）（2）（3）（4）（5）（6）设放电源传播到、的时间分别为，v为超声波速度。则（7）（8）（9） （10） （11）当在变压器箱壳上放置传感器时，可决定、的位置，用多通道示波器测量和、的时间，因此，放电源的位置可由公式（1）（11）解出。因为变压器内部结构很复杂,这是复合不同的材料,如石油、铜、硅钢等等。超声波传播路径不是完整的线性,但它是包括一些折射。因为超声波的频率非常高,折射是非常小的。因此,通过超声波信号,我们可以精确地检测到局部放电的位置。我们使用多个传感器,更多我们得到准确的位置。（2）变压器局部放电测试测试方法局部放电测试用电源的五倍频率250hz,施加试验电压在变压器的低压绕组。检测阻抗连接到测试的最后一层套管绝缘纸，然后链接到通过数据电缆测试仪。为了补充变压器的容性电流，将一些电抗器并联到变压器低压侧，当作测试电压。在测试之前，将方波与500pc电荷充电，注入高（中）电压最后一层壳体绝缘纸校准放电