Elektrotehnìka ta Elektroenergetika (Oct 2018)
FUZZY MODELING OF FAILURE PROBABILITY OF APARATES FOR PROTECTION FROM OVERVOLTAGE
Abstract
Purpose. The aim of the article is to develop a mathematical model for a comprehensive assessment of the probability of failure of an overvoltage protection device using a fuzzy set device, which is based on expert knowledge and diagnostic data obtained during the operational period. Methodology. The study was carried out using the expert survey method, weight coefficients method, Saati pair comparison matrix method, fuzzy logic methods, fuzzy sets theory, high voltage technology theory, thermal radiation theory. Findings. The authors developed a fuzzy model for determining the probability of failure of a gate arrester and a voltage limiter, taking into account the influence of a combination of such factors as the state of insulation, the state of current-carrying nonlinear elements, the temperature state of the object under study, and the number of operations of the apparatus. On the basis of the model, an automated software system was developed, using which the state of the voltage limiter type 3ER2 276-2PF32-1NA1 of the «SIEMENS» company was diagnosed. It is operated at Dneprovskaya HPP-1, 330 kV for cell ОПН AT-331, and arresters of type РВМК -750M for cell PB 750 2 AT. Originality. The theory of technical diagnostics of high voltage overvoltage protection devices without disconnecting devices from the network (online) on the basis of a fuzzy model for determining the probability of failure of the device has been further developed. The known model differs from the known ones in that it takes into account the state of insulation, the state of the conductive parts, the number of operations of the apparatus, the thermal state of the apparatus and the contact connections, and allows calculating the probability of failure of the apparatus during its operation. Practical value. The developed mathematical model can be used in automated software and hardware-software systems for: diagnosis, maintenance and repair planning, and distribution of financial assets of electric power enterprises. The results of diagnosing different protection apparatus confirmed the adequacy of the developed model. The developed model can be used for all types of protection devices for high voltage switchgears. The model makes it possible to comprehensively evaluate the technical state of the investigated object by integrating the input parameters (current, resistance, temperature, etc.) that are inherently different in nature and which affect the technical state and the probability of its failure. The constructed model allows the machine to be put out of repair after the current state of the object, and not according to the schedule of repairs, which will save the material and human resource, and taking into account the state course for estimating the equipment resource according to the actual state and creating switchgears without a permanent maintenance staff is very relevant.
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