When alternating current（AC） cable distribution lines are transformed into direct current（DC） lines

studying the operating parameters of cables under different DC topological structures is of great importance for the effective utilization of the power supply capacity of the existing lines. By using the finite element analysis software ANSYS for the typical XLPE cable widely used in 35 kV and 66 kV AC grid

we developed a simulation model for temperature and the electric field coupling. The temperature field and the electric field were simulated for the cables in different DC operation modes.To avoid the effect of the space charge

the DC voltage ranges of the selected 35 kV and 66 kV cables are ±25～±40 kV and ±40～±65 kV in the two DC operation modes

respectively. For the AC cables in DC operation

as the AC voltage level increases

the ratio of maximum transmission power after and before reconstruction gradually decreases. The conclusions in this paper can provide some references for the related engineering.