Simulation Of Current-carrying Lifting Scheme For Casing High-voltage Cables

Power cable is one of the important devices for power transmission.Because buried underground,they have a high reliability of transmission and do not affect the beauty of the city.At present,the demand for electricity in the society is increasing rapidly,and the underground power transmission corridors can not solve the problem.For this reason,the cable pipe has become an important laying method for urban power cables.However,when the cable is laid using a cable group,the heat dissipation conditions are poor,and that can result in a high internal temperature of the cable,which severely limits the ampacity of the cable line.Based on the IEC-60287,this paper calculated the thermal resistance conductor loss,dielectric loss,and metal sleeve power dissipation factor of conductors of 64/110 k V1x1000mm2 and 127/220 k V 1x800mm2 power cables.In addition,after learning the relevant knowledge of temperature field,the governing equation and boundary conditions of the temperature field of underground cable,the finite element method was used to study the temperature field of underground cable.Then,the Finite element method was used to establish the temperature field simulation model of the underground cable laid in 3×3 rows of pipes.The chord method is used to iterate the ampacities quickly and accurately under different operating modes.The temperature field and current carrying capacity of underground cable were analyzed under different operating modes.At the same time,the current-carrying capacity of the material filled with different thermal conductivity coefficients in the row tubes was calculated,and the influence of the thermal conductivity of the packed tube material on the current carrying capacity was investigated.It was found that when a concrete having a thermal conductivity of 1.51 W/(m·K)is filled between the cable and the grommet,the current carrying capacity is increased by19.05% compared to the case without filling.When the thermal conductivity of the filler increases under 10 W/(m·K),the current carrying capacity increases rapidly,and after 10W/(m·K),the current carrying capacity increases slowly.When the thermal conductivity of the filler is 10 W/(m·K),the cable current carrying capacity is increased by 21.29% compared to the case without filling,and this can provide a reasonable reference for finding and applying suitable filler materials.In addition,the condition of the current-carrying capacity of A and C phase-filled with soils and only B phase filled high thermal conductivity materials was considered in this paper.While the thermal conductivity of the filler material is 1.51W/(m·K),the current carrying capacity is increased by 15.79%.It can reduce the constructioncost while improving the current carrying capacity,and provide a new idea for improving the underground cable current carrying capacity.