变压器套管传热性能的数值模拟和试验验证

Numerical Simulation and Experimental Study of Heat Transfer Characteristics in Transformer Bushing

为获得较为准确的变压器套管温度分布情况,以某油纸绝缘套管为研究对象进行了数值计算分析和温升试验测量。首先通过有限体积法和热–流耦合分析得到了套管在长期稳定工作下的温升分布。计算中使用Bossinesq来近似处理空心导电杆内和芯子–伞裙间隙中的变压器油在传热过程中的对流作用。计算表明变压器套管在3 150A电流载荷下长期工作时温升最高点位于靠近法兰部位的导电杆上,为77.261℃。套管导电杆内部的油和芯子部位的油与壁面的对流换热系数约为100 W/(m·K),表明了油的缓慢流动对于套管内部传热起到了较为明显的作用。通过温升试验测量套管导电杆和外表面温度值,测量结果表明在导电杆的21个点上温度计算值与测量值误差<6%。证明使用的套管温度计算方法可靠,可以在工程中指导变压器套管的结构设计和校核。

To achieve an accurate temperature distribution of transformer bushing, we numerically and experimentally studied an oil-paper bushing. Firstly, the finite volumes method （FVM） and coupled thermal-fluid field were utilized to obtain the temperature distribution after a long time work. The effect of free convection heat transfer effect of oil, which fills the gaps inside the conductor and between the core and umbrellas, was taken into consideration among simulation through the Bossinesq approximation. Simulation results show that the peak value of temperature rise on bushing, which has been operating under 3 150 A current load, reaches to 77.261 ~C. The peak value turns up on the center pilot. The convection coefficient between oil and surfaces, located in the conductor and near the core, is about 100 W/（m.K）, which just proves its significant influence on heat transfer in bushing. After simulation, a temperature test was carried out to detect temperature on both the conductor and outer surface. Experimental results show that the computing error for 21 detecting points on the conductor is less than 6%. It can be concluded that the method is proper and can improve the de- sign and analysis of transformer bushing.