Study On Characteristics Of Partial Discharge And The Gas Generation Law For The Typical Defects In Transformer Internal Insulation

Power transformer is one of the crucial equipment of power system , partial discharge would affected seriously transformer safe operation. This paper establishes a simulation experiment system of transformer partial discharge in the laboratory, through analyzing the common fault characteristics of transformer internal insulation and gas production mechanism, selects three kinds of typical defect models as the main research objects, makes use of boost and constant pressure methods to research the typical defect partial discharge characteristic of the transformer internal insulation, emphases on the analyses of the variable law of the dissolved gases in oil during the development process of the partial discharge, and explores the correspondence between the gas produced in oil and the partial discharge.â‘ The paper establishes a simulation experiment system of power transformer partial discharge in the laboratory. According to the three kinds typical defect model existed in the internal insulation of power transformer, this paper designs three kinds partial discharge models, that is air-gap discharge of solid insulate in oil, corona discharge in oil, and oil-paper insulation surface discharge model, carried out partial discharge test.study based on the modelâ‘¡In the process of discharge development to insulation breakdown, the maximum amplitude of three kinds discharge model is the increase as the voltage tends to rise. With the time increasing, the maximum amplitude variation law of each discharge model presents their special characteristics. The maximum amplitude variation law of each discharge model is as follows: air-gap discharge showed a U-type curve; corona discharge was L-curve; surface discharge is similar to V-type curve.â‘¢By the boost and constant pressure method, this paper applies the dissolved gas composition, content and gas production rate to analyze three kinds of typical partial discharge along with voltage and time variation trait.In the boost pressure method, the gas content of different type discharge have different trend in different voltage levels;in the constant pressure method, with the increase of time, different type discharge have different development trends. Trough a large number of experimental data is compared and analysed, different type partial discharge carries out identification by these differences.â‘£In the constant pressure method, the absolute gas production rate which the national standard recommended is introduced to characterize the gas differences of the different type discharge. Fitting results on the gas production rate is as follow: air-gap discharge showed a U- type curve; corona discharge was L-type curve; surface discharge showed a V-type curve. Combined with the basic characteristics parameter analysis of partial discharge, this paper found that the variable trend of characteristics gas production rate is similar to the maximum amplitude of partial discharge, absolute gas production rate can be used to reflect the development status of partial discharge.