Research On The Tehnology Of Winding Frequency Response Character And Diagnosis For Power Transformer

Frequency response analysis is an important method to detect the transformer winding deformation. It has important significance to ensure the safe and stable operation of power transformer to raise accuracy of the frequency response analysis.Frequency response analysis includes two sections, which are data testing and data analysis. Data testing gets frequency response data through testing. Data analysis judges transformer winding deformation through analyzing frequency response data. At present, the data testing technology is becoming mature, but the data analysis technology has problems. Two methods are usually used in data analysis, one is correlation coefficient method, which has been written in DL/T911, the other is judging according to the experience of professionals and the basic laws of frequency response data. Practice shows that the first method is seldom used because its misjudgments rate is high. The accuracy of the second method is higher when the method is used by experienced professionals, but this kind of experience method is also obviously insufficient. One hand, rich experience is needed in second method, the professionals with less experience could not use it well; on the other hand, because of the dispersion and uncertainty of the experience, the standardization of the method is hard, different professionals could get different conclusions, and it brings about difficulties to maintenance decision.For the problems in data analysis, the main contents of this paper are shown as follows: some successful experiences were summarized, the characteristics of the data were analyzed, 'Graphics Method' and 'Extreme Points Method' were studied for processing data, new characteristic quantities were obtained, the experience of professionals was expressed in mathematical ways by using of 'Graphics Method' and 'Extreme Points Method', 'Block Frequency Point Method' and its criterion were proposed for judging transformer winding deformation by frequency response data analysis, a software based on the new method was developed. The new data analysis technology need not depend on the experience of professionals and could get a better result the same as judging by experienced professionals, also the new technology is satisfied with the requirements of data analysis on standardization, uniqueness of result, and carrying out easily.