开关柜温度-流体场优化计算研究

Optimum simulation of thermal field for switchgear

针对开关柜温度-流体场计算量大、精度低等问题,从网格控制、边界条件及热源计算3个方面对其进行优化计算。首先提出了基于后验误差估计的网格修正方法,实现网格高效加密并减少冗余,在相同计算精度的条件下,所得网格的单元量仅为传统整体加密法的32.3%;通过建立开关柜外流场模型确定开关柜外壳截断边界,代替依赖经验的人工取值方法,得到无通风自然对流环境下外壳的对流换热系数为0.4~1.4 W/(m^2•℃);进一步建立了开关柜电磁-温度-流体耦合计算模型,利用涡流场求解开关柜内热源分布,充分考虑交流热源、接触热源、涡流损耗对温度场的影响。将上述方法应用到KYN28A-12kV/630A开关柜的温升计算中,并与试验结果进行了对比,仿真与试验最大相对误差3.43%,证明了方法的有效性。

Regarding to the problems of huge calculation and low accuracy in thermal-fluid coupled field for switchgear,optimum simulation was carried out from the aspects of grid controlling,boundary conditions and heat source calculation.Firstly,the grid adaption method based on posterior error estimation was proposed to achieve efficient mesh refinement with less redundancy.The adapted mesh size is only 32.3%of that obtained with the traditional global-refining method.Then,an external flow model was built to obtain the truncated boundary condition of the shell,replacing the determination process dependent on empiric values.Results show that the convective heat transfer coefficient under natural convection environment is 0.4 W/(m^2·℃)~1.4 W/(m^2·℃).Afterwards,the eddy current field was used to obtain the heat generation in switchgear and the electromagnetic-thermal-fluid coupled simulation was built so that the influence of current non-uniformity,contact heat and eddy loss were considered.At last,the methods were applied to the temperature rise simulation of KYN28A-12kV/630A switchgear and the results were compared with the test data.The maxi-mum relative error between simulation and experimental results is 3.43%,which proves validity of the mentioned methods.