Study On Load Capacity Online Assessment And Cooling Control Strategy Of Oil-immersed Power Transformer

Load capacity of oil-immersed power transformer is an important safety and performance indicators. Transformer outage due to load capacity limitation or overload may probably cause power blackouts, which will result in economic damage and social impacts. This paper has mainly studied the oil-immersed power transformer heat balance calculation method, load capacity evaluation model and the cooling system control strategy in order to fully exploit the potential of transformer load and enhance the economic and intelligent level of transformer operation. The paper research contents and the main achievements include:The calculation method of temperature field of oil-immersed transformer based on the finite element method and the finite volume method was proposed.The mathematical model of temperature field and flow field of oil-immersed transformer were established. The heat transfer process in oil-immersed transformer and appropriate method were studied, and then the calculation method of temperature field, which combines the finite element method and the finite volume method was proposed. Effects of transformer design parameters, load rate and ambient temperature, cooler fan running state and other parameters on temperature field distribution and the hot-spot temperature were analyzed.Key parameter of hot-spot temperature calculation of oil-immersed power transformer was optimized.Types and structure parameters of transformer greatly influence the stability precision and dynamic features of calculation results. Through simulation and verification optimum especially for key technical parameters of typical structure of transformer, this paper proposed advice of advised selection principles of hot-spot temperature calculation parameters, which can increase calculation accuracy and dynamic tracking features of the calculation precision.The calculation method of oil-immersed power transformer load capacity calculation based on the load prediction was proposed. Effects of load rate and ambient temperature on temperature field distribution were simulated. The prediction model of top oil temperature was proposed through construction of the state equation and measurement equation by Kalman filter and optimum estimation model. The load capacity assessment of transformer was proposed based on the load prediction to achieve dynamic assessment of overload capacity and sustained time.The intelligent control strategy of oil-immersed power transformer cooling system based on bayesian decision was proposed.Effects of cooling control strategies on temperature field distribution of transformer were stimulated at different load and ambient temperature. The intelligent cooling control strategies based on bayesian decision were studied to establish intelligent cooling control model with comprehensive factors analysis, such as top oil temperature, hot-spot temperature, load current, grounding current of iron core, isolation oil chromatograph data, and so on. The intelligent control strategy of oil-immersed power transformer cooling system based on bayesian decision was proposed and applied to actual control system, the application effect was good.On-line assessment system of oil-immersed power transformer load capacity was developed. Based on calculation method of temperature field and research result of load capacity, the models of on-line assessment were established which used multi-source information as input, such as design parameters, temperature rise test data, and operating data. Through this, the paper proposed the solution of load capacity online assessment and the cooling system intelligent control based on multi-source information, and achieved engineering application, the application effect was proved to be good.