排管内部强制水冷对地下电缆载流温度场的影响

Influence of Forced Water Cooling in Duct on Temperature Field of Underground Power Cables

为了提高地下电缆输电载流量,提出在排管内通入冷却空气或铺设冷却水管2种强制冷却方法,以提高地下电力电缆载流量。建立了在3×3阵列的排管内部直接通入冷却空气和铺设水管(铜管或PPR管)条件下的计算模型,根据IEC 60287标准计算了铜芯绞线损耗、铝护套损耗和绝缘介损,采用有限元方法计算了不同冷却条件下冷却空气和冷却水的雷诺数、努塞尔参数及对流换热系数,模拟了排管内部强制气冷和强制水冷条件下的电缆温度场和最大载流量。计算表明,采用排管内强制冷却可以显著提高电缆载流量,且随着管内空气速度或冷却水流速增大,冷却效果更明显。通过排管内强制冷却,可使电缆最大载流量由1560 A提高至2000 A,输电效率提升28%。

In order to improve the ampacity of underground cables,the paper proposes two methods for forced cooling including air cooling and water cooling in duct.The calculation model is established of 3×3 arrayed ducts with the air cooling and copper/PPR pipe laying with the water cooling.According to IEC 60287,the loss calculation of copper stranded wire,aluminum sheath and insulated dielectric is made,the Reynolds number,Nu and convective heat transfer coefficient of cooling air and cooling water under different cooling conditions is computed with finite element method,and the temperature field and the maximum ampacity of the cables in the duct with the forced air cooling and water cooling is simulated.The results show that the ampacity of the cables is increased significantly to 2000 A from 1560 A by using the forced cooling in the duct,meaning the transmission efficiency can be improved by 28%,and the cooling effect actually improves as increasing the air and water flow velocity.