Study On Miniaturization Of Power Transformer Based On Electric Field Optimization

With the rapid development of state grid, the amount of generation and electrical power supply increases greatly year by year. The demand of voltage level of power transformer has been higher and higher. To improve voltage level of power transformer, the volume of power transformer is enlarged to meet the requirement of the product specification and engineering. However, the price of transformer raw materials has achieved the unprecedented increase because of the shortage of global energy resources, so energy saving and cost control become the development trend of transformer industry.In this thesis, according to the technical requirement, voltage level and the initial design structure, for satisfying the manufacturing technical condition and engineering requirement, the numerical simulation of the electric field and analysis of insulation performance for 110kV power transformer has been studied. Aiming at the structure characteristic, the mathematical model of electric field of main insulation has been established. The distribution of electric potential and electric field intensity are derived for several structures. Moreover, the simulation results of different structures have been obtained and analyzed. Besides, the effect of angle ring, electrostatic ring, the main insulation distance and the distance between windings end and iron yoke on electric field distribution is also discussed. Then the relation between influencing factors and the maximum electric field intensity is obtained.Using the optimization design module of FEM analysis software, finite element analysis and optimization design are made to the main insulation of 110kV power transformer. The optimal size of the insulation and most reasonable structure of the main insulation are obtained. Compared with traditional main insulation structure, the main insulation distance, the distance from windings end to iron yoke and the arrangement and shape of angle rings of improved main insulation structure are improved significantly. It reduces horizontal and vertical size of power transformer, and save manufacturing cost.The improved main insulation structure is verified by simulating winding wave process and calculating temperature rise. The results indicate that the improved main insulation structure can meet the requirements of reliability. The method of analyzing and calculating electrical field is suitable for different voltage level of power transformer main insulation design and having extensive applicability.