混合绝缘液浸电力变压器的热-流耦合场分析及绝缘和散热器结构的改进

Analysis of Thermal-fluid Coupled Field for Fluid-immersed Power Transformer with Hybrid Insulation System and Improvement of Its Insulation and Radiator Structures

由于传统的变压器温升计算公式不再适用于混合绝缘结构的液浸式新型电力变压器设计,为此笔者采用传热学和流体动力学原理建立了变压器热流耦合场的有限元模型,模型中考虑了变压器油热力学参数的非线性和绕组结构中垫快、纸筒对散热的影响,并根据不同的绕组形式进行单元离散。通过对混合绝缘结构的液浸式变压器热-流耦合问题的求解,得到了变压器内部各点的温度和流场分布状况,高低压绕组平均温升与试验结果吻合。结合计算和试验结果对变压器的绝缘材料进行了改进,充分发挥了材料的耐温特性和经济性。最后,提出了通过升高散热器进出口的高度差来达到降低变压器热点温升的有效方法。

Because the traditional calculation method of transformer temperature rise is not suitable for the design of fluid-immersed power transformer with hybrid insulation system, this paper built a finite element model of thermal-fluid coupled field for power transformer based on the heat transfer theory and fluid dynamics. The thermodynamic parameter nonlinearity of transformer oil and the effects of bearings and fiber containers in winding construction on heat radiation were considered in this model. Moreover, unit discretization was conducted according to different winding forms. The temperature and flow distributions at different spots in transformer were achieved by the thermal-fluid coupled method, and the results show excellent agreement with experimental ones. The insulation material of transformer was also improved according to computation and measurement results. At last, a method to reduce temperature rise of thermal wallis proposed by expanding the height difference between exit and inlet of radiator