Temperziature Field Modelling And Cooling Evaluation Method Of The Discrete Transformer

As urbanization continue to accelerate,population density surge,construction of high rise building,centralization of electrical load and other features have started to emerge in large cities,causing lack of available ground space within the cites.Thus,the application of discrete transformers in large cities has taken place as a result of the above phenomenon due to its combination of advantages of both dissipation efficiency and space saving.The fundamental difference between the discrete transformer and the conventional transformer is that the cooling system is designed to separate from the transformer body.This structural feature has diversified the characteristics of system cooling between the aforementioned two types of transformers.As the insulation is of crucial importance to the life of transformers and the insulation is mainly affected by the temperature of transformers,the research of investigation of the temperature distribution inside transformer is of significant meaning to both the stable operation and the service period of the transformer.Other than this,besides the online guidance provide by the manufacturer of the transformer,there is so far,not been a mature method in evaluating the cooling performance and efficiency of the transformer cooling system.Therefore,the content of this thesis contains mainly the following content.This thesis presents calculation of the temperature field and flow field of the discrete transformer using finite element method.To ensure the accuracy as well as the computing speed,the transformer model provided in this thesis has converted from its original 3-dimensional model into a 2-dimensional model.This model has been used to compute the temperature distribution field and the oil flow distribution,the results have been compared with experiment results acquired from actual site.The result has shown that the simulation results are mostly reliable.Then,this thesis provided comparison of the temperature field of the conventional transformer and compared the results with the discrete transformer to analyze the differences due to the transformers' structural difference.To further investigate correlations between the cooler relative position and temperature distribution,this thesis provided investigation results based on both horizontal and vertical relative position.Further discussions on top layer oil temperature,entry and exit oil temperature and oil flow speed are also given.Besides providing temperature field distribution,this thesis also provided a different way of solving for cooling evaluation.By selecting reasonable evaluation criteria for discussion and establishing discrete transformer cooling efficiency evaluation system,the cooling evaluation system for discrete transformer using ADC Method is constructed.In this process,this these has practiced Analytic Hierarchy Process by considered a number of factors that affect the cooling efficiency and intricately formed them into a multi-layered and weighted evaluation system.To quantify specialists,qualitative evaluation,this thesis used fuzzy calculated algorithm to converter their opinions into actual measuring points,and represents quality using the converted points.By using the ADC method provided by this thesis,the quantitative evaluation of the cooling efficiency of discrete transformer is realized.