基于多孔介质理论的35kV油浸式变压器热点简化计算

Simplified Calculation of Hot Spots of 35 kV Oil Immersed Transformer Based on Porous Medium Theory

低电压等级的油浸式变压器绕组往往由漆包圆线绕制而成,其温升及热点的准确计算需要考虑漆包圆线间的缝隙对油流及温升的影响,而精细建模时建模工作量和数值计算量都非常大。针对这一问题,提出将多孔介质理论应用于油浸式变压器简化建模的思路。首先验证了多孔介质理论应用于油浸式变压器热点计算的有效性。其次,基于多孔介质理论建立35 kV油浸式变压器绕组的简化模型,采用Fluent软件计算出其温升热点分布。最后将变压器的多孔介质理论简化模型所得的仿真结果与光纤测量结果进行对比。结果表明仿真与实验的热点温度误差在4℃以内,热点位置与实验结果保持一致,验证了多孔介质理论简化模型计算方法的准确性。多孔介质理论的应用为大规模变压器3维流-热耦合提供了新的计算思路,有助于工程实际中变压器热点温度的简化计算。

The windings of low voltage oil-immersed transformers are often wound by enamelled round wires.In the process of the accurate calculation of temperature rise and hot spot,the influences of the gap between enamelled round wires on oil flow and temperature rise need to be taken into consideration,while the workload of fine modeling and nu-merical calculation is very large.Aiming at this problem,we propose the idea of applying porous medium theory to the simplified modeling of oil-immersed transformers.Firstly,the validity of porous medium theory applied to the hotspot calculation of oil-immersed transformers is verified.Secondly,based on the porous medium theory,a simplified model of 35 kV oil-immersed transformer winding is established,and the distribution of its temperature rise hotspots is calculated with the Fluent software.Finally,the simulation results of the simplified porous medium model of the transformer are compared with the optical fiber measurement results.The results show that the error between the hot spot temperature of the simulation results and the experimental results is within 4℃,and the hot spot position is consistent with the experi-mental results,which verifies the accuracy of the calculation method of the simplified model of porous media theory.The application of porous medium theory provides a new calculation idea for the 3D fluid thermal coupling of large-scale transformers,which is helpful to simplify the calculation of transformer hotspot temperature in engineering practice.