DETERMINATION OF THE VALUES OF THE BOUNDARY CONCENTRATIONS OF GASES TAKING INTO ACCOUNT THE TYPE OF PROTECTION OF OIL OF HIGH VOLTAGE TRANSFORMERS

• Main Author: O. V. Shutenko
• Format: Article
• Language: English
• Published: Zaporozhye National Technical University 2018-12-01
• Series: Elektrotehnìka ta Elektroenergetika
• Subjects: dissolved gas analysis; gas content of transformers with different types of oil protection, concen-tration levels, gas with maximum content, boundary values of gas concentrations; Weibull distribu-tion; density functions, minimum risk method, Nelder-Mid method
• Online Access: http://ee.zntu.edu.ua/article/view/153824

Purpose. Development of a method for determining the boundary values of gas concentrations, taking into account the characteristics of the gas content of equipment with different types of oil protection. Methodology. Statistical analysis, testing the hypothesis of the proposed distribution of experimental values, methods of statistical solutions, the method of minimal risk, the Nelder-Mead method. Findings. The results of a comparative analysis of the gas content in sealed and unsealed transformers are presented. It has been established that the concentrations of gases dissolved in oil of serviceable autotransformers 330 kV of hermetic construction can be described by the Weibull distribution. A method for determining the boundary values of gas concentrations, based on minimizing the mean risk function, is proposed. The analysis of the mean risk values, using the boundary values obtained by the author and typical gas concentrations regulated by known standards, showed high reliability of the proposed method. Originality. A method is proposed for determining the boundary concentrations of gases dissolved in oil, which provide the minimum value of the average risk in diagnosing the state of transformers from the concentrations of gases dissolved in oil. This method differs in that the boundary values of gas concentrations are obtained by minimizing the mean risk function for multidimensional distributions by the Nelder – Mead method. Practical value. The proposed method allows determining the boundary values of gas concentrations, taking into account the characteristics of the gas content of the equipment, its design, operating conditions, the sort of transformer oil and a number of other factors. The resulting values of boundary concentrations provide minimal risk values, compared with the risk values that are accompanied by the use of typical gas concentrations, which are regulated by the applicable standards.