Bolotnyi M. Improvement of mathematical models for rating power transformer technical condition to increase the reliability of emergency risk assessment on subsystems of electric power system

The thesis is devoted to the decision of the actual scientific and applied task of increasing the efficiency for subsystems functionality of electric power system by estimating the emergency risk under power transformers failures in conditions of incompleteness and uncertainty of information. The conducted researches allow to make the following conclusions: 1. Improved mathematical model of technical condition assessment for power transformer, unlike the existing ones, is based on the processing of diagnostic information by using fuzzy set theory and allows to identify defects without out of service by the results of chromatographic analysis of dissolved gases in transformer oil. 2. Improved mathematical model for failure risk assessment of power transformer, unlike the existing ones, on the basis of technical condition, allows to increase the reliability of determining the emergency risk in the subsystems of electric power systems under disturbances in the external power grid. 3. The complex approach for emergency risk assessment in subsystems of electric power systems under emergency or planned out of service of power transformers is developed, which, unlike the existing ones, is based on the failure risk assessment of power transformer and probabilistic-statistical simulation of the modes for electric power systems in conditions of incompleteness and uncertainty of information allows to increase the accuracy of emergency risk assessment violation in the subsystems of electric power systems. 4. The method of determining the priority of power transformers out of service is proposed, which, unlike the existing ones, takes into account technical condition, reliability level of power transformer for electric power systems, allows to form preventive solutions to reduce the emergency risk in case of emergency or planned out of service for power transformers. The using of developed methods, mathematical models and software can significantly increase the subsystems reliability of electric power system and auxiliary systems of the power plant due to: - to increase the reliability of the determination for technical condition of the power transformer and the its failure risk, which makes it possible to make well-informed decisions in a timely manner regarding the further operation strategy on given time interval; - to perform a reliable assessment the failure probability of power transformers in electric power system and its ranking on reliability; - to identify the most "weak" ones in the reliability of unit and the electrical equipment group; - to make informed decisions about operation strategy of power transformers taking into account individual characteristics; - to reduce an emergency risk situation in the subsystems of electric power system and the power supply systems of the auxiliary systems for the power plant. The obtained results of complex simulation of the electric power system state and technical condition of the electrical equipment give grounds to assert the possibility of software implementation of operation risk analysis of the electric power system for power supply companies.