油浸式变压器热点温升计算中绕组结构简化的误差分析

Error Analysis of Winding Structure Simplification in Hot Spot Temperature Rise Calculation of Oil Immersed Transformer

变压器温度流体场三维仿真是准确计算变压器绕组热点温度的重要方法,然而变压器绕组结构复杂,精确三维建模和网格剖分困难,计算效率低,难以满足实际工程需求。文中针对变压器温度流体场计算过程中绕组结构类型以及撑条、垫块、外包绝缘纸对绕组热点温度的影响进行了讨论,在一定的容许偏差内对绕组结构进行简化分析,得到以下结论:网格控制方法及剖分精度对计算结果有较大影响,采用扫描剖分方法能够在绕组附近区域获得高质量的六面体网格,具有较高剖分效率;对温度、流速等变化较快的区域进行局部加密,通过逐级局部加密的方式完成流体计算中的网格独立性验证,可在保证计算精度的情况下提高计算效率;稳态条件下撑条、垫块及绕组外包绝缘纸对绕组热点温度计算的影响较小,误差控制在1℃以内,建模时可以选择简化。文中的研究成果为今后具有类似结构的油浸式变压器热点温度三维仿真计算提供了参考。

The three-dimensional simulation of temperature fluid field of transformer is an important method to accurately calculate the hot spot temperature of winding of transformer.However,the structure of the winding of transformer is complicated,the accurate three-dimensional modeling and meshing are difficult,the calculation efficiency is low and difficult to meet the actual engineering requirements.In this paper,the influence of structural type of the winding,strut,spacers and the outer insulation paper on the hotpot temperature of the winding during the calculation of temperature fluid field of transformer is discussed.The winding structure is simplified and analyzed within a definite allowable deviation and the following conclusion is obtained:Both grid control method and division precision have great influence on the calculation result.The use of scanning division method can obtain high quality hexahe-dral grid near the area of winding and can get higher division efficiency.The local encryption is carried out in the area with rapid variation of temperature and velocity.The independent verification of the grid in the fluid calculation can be finished through the step-by-step encryption which,on the condition of assuring calculation accuracy,improves the calculation efficiency.The influence of structural type of the winding strut,spacers and the outer insula-tion paper on the hotpot temperature of the winding is less and the error is controlled within 1℃and the simplification ca be selected in the modeling.The research results in this paper provide a reference for the three-dimensional simulation calculation of hot spot of oil immersed transformer with similar structure in the future.