油浸式变压器绝缘纸热阻的温度特性

建立并优化变压器温度场分析的热路模型,是研究变压器绕组热点温度的重要途径,在完善油浸式变压器热路模型和提高其模型精度过程中,绝缘纸热阻参数的确定尤为关键。针对绝缘纸与紫铜接触界面填充变压器油的情况,通过原子力显微镜观测绝缘纸与紫铜表面微观结构,结合观测数据改进接触热阻模型,计算出了不同温度下油浸绝缘纸与紫铜间的接触热阻。改进了双热流计法,并测试了不同温度下紫铜与油浸绝缘纸的接触热阻。结果表明,在70℃时紫铜与油浸绝缘纸接触热阻计算值为0.000 541 m^2·K/W、实验值为0.000575m^2·K/W,并且随温度升高油浸绝缘纸导热系数减小,紫铜与油浸绝缘纸接触热阻变大,研究中5个温度点的接触热阻实验值与理论值平均误差为6.49%。该研究结果为建立并优化变压器热路模型的等效回路提供数据支持,具有较好的应用价值。

Temperature Characteristics of Thermal Resistance of Insulating Paper for Oil Immersed Transformer

Establishing and optimizing the thermal path model of transformer temperature field is an important way to analyze the hot spot temperature of transformer windings.In the process of improving the thermal path model of oil-immersed transformers and improving the accuracy of their models,the determination of thermal resistance parameters of insulating paper is particularly critical.In order to analyze the case that the insulating paper and the copper contact interface are filled with the transformer oil,we observed the microstructures of insulating paper and copper surface by atomic force microscopy.According to the observation data,the contact thermal resistance model was improved,and the contact thermal resistance between the oil-impregnated insulation paper and the copper at different temperatures was calculated.Therefore,we improved the dual heat flow meter method and tested the contact thermal resistance of copper and oil-impregnated insulation paper at different temperatures.The results show that the thermal resistance of copper and oil-impregnated insulation paper at 70℃is calculated to be 0.000 541 m^2·K/W and is tested to be 0.000 575 m^2·K/W.As the temperature increases,the thermal conductivity of the oil-impregnated insulating paper decreases,and the thermal resistance of the contact between the copper and the oil-impregnated insulating paper becomes large.The average error between the experimental and theoretical values of the contact thermal resistance at five temperature points in the study is 6.49%.The research results provide a data support for establishing and optimizing the equivalent loop of the transformer thermal circuit model,and have good application value.