Hryshchuk M. Methods and Means for the Diagnostics of Power Transformers of Electrical Distribution Systems with Photovoltaic Power Stations

Hryshchuk M. Methods and tools for diagnosing power transformers of electrical distribution networks with photovoltaic stations. - Qualifying scientific work on the rights of the manuscript. The dissertation on competition of a scientific degree of the doctor of philosophy in the direction of preparation 141 - "Electric power, electric engineering and electromechanics" on a specialty 14 - "Electrical engineering" - Vinnytsia national technical university, Vinnytsia, 2020. This dissertation is devoted to the study of frequency response analysis in order to improve existing methods for diagnosing power transformers. In the dissertation the actual problem on definition of a technical condition of the power transformers operated in distributive electric networks with photovoltaic stations is set and solved. The scientific novelty of the obtained results submitted for defense is that: - further developed a method of optimizing the technical condition of power transformers, which by taking into account the errors of measuring instruments allows to determine the number of repeated experiments, which reduces the errors of the first and second kind; - further developed a method of determining the optimal sequence of tests of power transformers depending on changes in the results of inspection of power transformers, operational staff, which by taking into account the result of external manifestations of the defect, allows to choose the optimal sequence of control and reduce ; - further developed a method for determining the defects of power transformers by comparing the amplitude - frequency characteristics, which by controlling additional diagnostic parameters, proposed by the results of the detected deviations of the amplitude - frequency characteristics allows to confirm or refute the defect predicted by the control of amplitude - frequency characteristics; - further development of the method of determining the optimal number of tests, which by using D-optimal plans, reduces the error in determining the technical condition of power transformers. The practical significance of the obtained results is defined as: - algorithms for determining the technical condition of power transformers have been developed during a specific inspection of 6-35 kV power transformers; - the software of the device of complex diagnosing is developed; - developed a software tool for determining the optimal number of measurements during complex diagnosis. In general, the conclusions from this dissertation can be used by both operating companies and those who serve such companies. The use of the proposed methods will reduce the cost of technical diagnostics of the power transformer, and improve the quality of the results.