The temperature of power cables in an underground cable conduit,which depends on ambient environment and operational current,can reach levds in excess of the maximum allowed values in summer.Over temperature due to accumulation of heat accelerates the aging of power cable insulation materials,and increases risk of fire accident.In order to limit the operating temperature of cables in an underground cable conduit,an optimization method is proposed in this paper to reallocate the current ratings of the multiple cable circuits in a cable conduit.Based on the finite element method,the temperature field in an underground conduit which houses a group of cables is calculated.An optimization model of reallocating the current in the cable group is established.On the basis that the temperature of the highest temperature cable in the cable group should never be allowed to exceed 90 ℃,and achieves a minimum and that the total current of all the cables in the conduit should remain unchanged,the cable with the highest temperature in the cable group is optimized by distributing its current.It is found from results of simulation by Comsol Multiphysics that,compared with before the results of not adopting the proposed optimization method,the conductor core temperature of cable with the highest temperature in the conduit is reduced by almost 11％ and the maximum temperature difference of among the cables in the conduit is reduced by 3.6 degrees,meaning that the uniformity of temperature field distribution of the cable group is increased after using the optimization method.%夏季地下排管电缆聚集运行温度异常,电缆温度过高会加速电缆绝缘材料的老化,热量累积到一定程度,还可能引起起火事故.为降低地下排管中电缆运行温度,提出了电缆群排管敷设形式的优化方法.基于有限元法计算地下排管中电缆群运行温度场,建立了电缆群敷设形式优化计算模型.以电缆群中最高温电缆的温度降到最低为目标函数,电缆群中总载流量不变为约束条件,对电缆群中温度较高的电缆进行分流优化计算.通过Comsol Multiphysics软件仿真计算的结果可见,与未优化之前相比,采用优化方法后排管中最高温电缆的导体芯温度降低了约11％,电缆群最大温差降低了3.6℃,增加了电缆群温度场分布的均匀度,优化效果显著.
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