高速电力机车主变压器三维油箱损耗分析及温度场计算

【作者】 李建州；

【导师】 罗隆福；

【作者基本信息】 湖南大学 ， 电机与电器， 2002， 硕士

【摘要】 虽然电力机车主变压器在原理上与普通电力变压器没有太大的差别，但是电力机车主变压器是高漏抗、多绕组变压器，当采用饼式、分裂式绕组时，由于横向漏磁场大，因此油箱的损耗也高。若不采取措施，较大的损耗会使金属构件局部过热，因此，精确的计算油箱损耗非常必要，但传统的计算方法是根据普通变压器的经验公式进行估算，对高漏抗变压器来说，误差较大，且无法准确估算局部过热点，因此需要采用更为准确的有限元数值计算方法。本文引入大型通用有限元软件-ANSYS软件，较系统分析了与研究内容相关的似稳电磁场的基本理论，以及有限元法的基本原理，其中重点介绍了边单元的概念与特点。采用ANSYS软件的边单元法，建立了高速电力机车主变压器油箱三维漏磁场模型，在此基础上较准确地计算出油箱损耗，并与二维计算结果进行了比较，结果表明：三维分析的结果更加准确，而涡流密度分布图为变压器油箱采取更好的屏蔽措施提供了直观的参考；建立了变压器油箱屏蔽的优化模型并采用子问题近似优化算法对油箱屏蔽尺寸进行了优化，在限制最大涡流密度的条件下，使油箱屏蔽体积最小，重量最轻。结果表明：优化后变压器油箱涡流密度分布更加均匀，总损耗降低了4％，但是体积却增加不多，能够为工程实际所接受；最后，建立了变压器油箱三维温度场的有限元模型，按照磁-热弱耦合方法，获得了优化前后油箱稳态温度场的分布，找到了油箱最热点的温升，证明了油箱屏蔽结构是合理的。更多还原

【Abstract】 Although there is no much difference in theory between electric locomotive main transformer and normal power transformer, electric locomotive main transformer is high leakage reactance and multi-winding one. The transverse leakage magnetic field is intensive when adopting cake and interleave windings, so the losses in tank is high. If no measurements have been taken, the tank wall may have local hot-spot which can deteriorate the transformer performance. It is necessary to calculate accurately the loss in the tank and estimate temperature rise of the hot-spot. The conventional calculating method is to estimate the loss in the tank according to empirical formula of normal transformer. It may have relatively large error for transformer made of high leakage reactance and cannot estimate the local hot-spot accurately, so more accurate finite element method (FEM) is needed. The large universal finite element software -ANSYS is introduced in this paper. The principal theory of quasi-static magnetic filed and rationale of FEM relative to the research is presented systematically, in which edge element method is emphatically discussed. 3-D leakage magnetic field model of high-speed electric locomotive main transformer tank is built using edge element method and accurate tank loss is calculated compared with 2-D analysis model. Result shows 3-D model is more accurate and eddy density distribution pattern provides intuitionistic help for taking better shielding measures. The tank shielding optimization model is presented by limiting maximum eddy density in tank and minimizing shielding volume. Optimization result through subproblem approximation optimization technique indicates eddy current density more uniformly distributed in tank and total losses decrease 4%, but shielding volume adds little, which can be accepted by practical engineering. 3-D steady state temperature field model of transformer tank is built and the local hot-spots and temperature rises before and after optimization are obtained using magneto-thermal weak coupling method. Results verify the rationality of tank shielding structure.更多还原