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 WangSichuan 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, its necessary and important to detect the partial 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. With 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 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 the main reason of the accident of transformer and power system. Therefore, its 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 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. 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 scatter 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 spread 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 by 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 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 the 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 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 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 internal structure is complex, which is compound of different materials, such as oil, copper, si