排管敷设电缆群温度场和载流量数值计算

Numerical Calculation of Temperature Field and Ampacity of Cables in Ducts

为充分利用电力电缆线路的传输容量,提高电缆的利用率,准确计算电缆线路的温度场分布,建立了地下排管敷设电缆群的热传导、热对流、热辐射微分方程,给出了2维共轭温度场的求解域和边界条件,利用涡量-流函数和伽略金法给出了自然对流的变分方程,利用迭代和耦合算法对方程进行了有限元分析和计算。给出了给定电缆负荷的温度场分布图,迭代计算了单回路和多回路交联聚乙烯电缆系统的载流量。排管内带绝缘发热管的试验和计算的对比,验证了计算模型的有效性。

The differential equations of heat conduction,heat convection,and heat radiation,which were in different heat media of groups of cable in ducts,were established.The solution domain and boundary conditions of two-dimensional conjugation temperature field were defined.The variation equations of natural convection were established by the vorticity-stream function and Galerkin method and calculated by the iteration method and coupled algorithm based on finite element method（FEM）.The temperature distribution of cables with given load was calculated.The ampacity of single loop and multi-loop XLPE power cable systems were calculated by iteration method.The results of test and calculation show that FEM is effective to calculate the temperature field and ampacity of underground cable systems in ducts in engineering.