Finite Element Analysis On The Vibration Characteristics Of Oil-Immersed Transformer Core And Windings

As capacity of the transformer is increasing, the importance of safety and operation steadily of the transformer has become more and more apparent, which needs more effective and accurate diagnosis of faults. According to the historical statistics, the number of faults on the winding is the most accounting for 1/3, while faults of the core ranked the second, following by 1/7. Therefore effective monitoring and accurate diagnosis to parts of the transformer is one of the effective measures to reduce the number of faults and improve the economy.This article focuses on a three-dimensional model of the oil-immersed transformer of S11-800/10, which combines finite element calculation with analysis of vibration signal. Through using Pro/E software for solid modeling of this oil-immersed transformer, and then choosing modal analysis module, harmonic response analysis module and instantaneous dynamics module in ANSYS to analyze this oil-immersed transformer.This article works as follows:Firstly, this article briefly introduces the main structure of oil-immersed transformer and a detailed description of the approach to vibration transmission. Theoretic analysis about vibration source of core and windings in addition to factors of vibration signal, and then establish mathematical model of axial vibration of core and windings.Secondly, brief introduction of convenience, interaction and other advantages about the three-dimensional model in Pro/E. On the other hand this chapter introduces diverse and comprehensive modules of ANSYS to analysis structure. Depending on the perfect connection between two software, this paper establishes finite element model of grid about core, windings, body and the fuel tank of the S11 oil-immersed transformerThirdly, call the modal analysis module to solve out the inherent frequencies of each part; call harmonic response analysis module to solve the amplitude-frequency responses of the core and windings in order to determine the frequency range in the respectively largest contribution to the vibration of the core and windings in the normal condition. Through comparison, we can effectively improve and optimize the structure of the core and windings. Assume the exciting force and the possible fault in different positions of core and windings to find out the curve features through amplitude-frequency responses in order to provide a basis for guiding practice of fault diagnosis.Fourthly, call the modal analysis module and harmonic response analysis module to the body and its internal component model, so as to understand the dynamic body features of oil-immersed transformer. During the analysis of the tank, consider the influence of oil to frequency and vibration mode of the tank and find out the position of the largest stress to optimize design.