基于多物理场仿真的低频变压器温度特性分析及导向结构优化

Temperature Characteristics Analysis and Guide Structure Optimization of Low-frequency Transformer Based on Multi-physics Field Simulation

为了降低低频工况下油浸式电力变压器的热点温度与内部温升,基于电磁-热-流体场多物理场耦合对低频变压器绕组区域导向结构开展优化分析。通过对变压器电磁部分的有限元数值计算,确定低频变压器与同工况下的工频变压器在铁芯和绕组区域的磁密分布与损耗特性区别。然后在此基础上将铁芯和绕组的损耗作为热源代入流体场和温度场进行仿真分析,得到变压器整体和绕组区域局部的温度及油流分布。最后通过构建20 Hz低频变压器绕组区域的油流传热模型,结合有限元仿真研究导油挡板数量与分布对绕组区域油流量、平均温度和热点温度的影响,并获得导向结构的最佳分配方案。研究结果表明,20 Hz低频变压器绕组区域的热点温度较无挡油板的模型下降了14.44%,该结果可为低频变压器紧凑化设计提供优化方案。

In order to reduce the hot-spot temperature and internal temperature rise of oil-immersed power transformers under low-frequency operating conditions,an optimization analysis is carried out for the winding-area oriented structure of low-frequency transformers based on the multi-physical field coupling of electromagnetic-thermal-fluid fields.Through the finite element numerical analysis of the electromagnetic part of the transformer,the difference between the magnetic density distribution and loss characteristics of the low-frequency transformer and the power-frequency transformer under the same working condition in the core and winding area is determined.And on this basis,the loss of the core and winding as a heat source is substituted into the fluid field and temperature field for simulation analysis to obtain the temperature and oil flow distribution of the transformer as a whole and the winding region locally.Finally,by constructing the oil flow and heat transfer model in the winding region of 20 Hz low-frequency transformer and combining it with finite element simulation,the influences of the number and distribution of oil guiding baffles on the oil flow,average temperature and hot-spot temperature in the winding region are investigated,and the optimal distribution scheme of the guiding structure is obtained.The results show that the hot-spot temperature in the winding region of the 20 Hz low-frequency transformer decreases by 14.44%compared with the model without oil baffles,which provides an optimization scheme for the compact design of the low-frequency transformer.