Diagnosis Of Transformer Insulation Using Frequency Study Of Aging

Electric power system in the operation of large power transformers in the electrical, thermal, chemical, electric power under the effect of insulation aging. According to incomplete statistics, the accident caused by aging of transformer insulation accounts for about half of the total incidents. Transformer is the power core of the system devices in the system is extremely important position. The event of failure, will likely result in a large area of the power outages, giving the power systems and cause incalculable damage to the national economy.This paper mainly introduces the transformer insulation aging mechanism, the impact of the main factors of transformer insulation, transformer insulation aging detection methods and the status of the advantages and disadvantages of each. As a supplement, increasingly importance has been attached to medium frequency domain (frequency) analysis.The thesis presents the measurement principle and its disturbance factor, as well as the method to obtain the complex permittivity of pressboard with a lumped circuit model.Aim at the relations of the complex permittivity of pressboard and moisture as well as temperature according to the experiment data and master dielectric frequency spectra, new functional forms of moisture content for oil free pressboard versus complex permittivity temperature and frequency are fited, which are easier to use and more objective. With three models, the efective dielectric constant of pressboard can be calculated.Finally,through laboratory accelerated aging test method to verify the frequency transformer insulation effectiveness and feasibility of the situation. According to field 220kV and 800kVA transformer tests results, frequency domain (frequency) analysis of transformer insulation aging is accuracy and reliability of certain.