Submarine cables are an important component of power grid construction

and the size of metal sheath circulation and armor circulation is an important reference for the design and operation of submarine cable engineering. In the existing literature

the overall line circulation size is not considered in the calculation of the temperature-field current-carrying capacity of submarine cables

thus the accuracy is affected. Therefore

we established a field circuit coupling calculation model that considers the overall laying conditions of the metal sheath

armor circulation

and cable temperature distribution. The circulation of the three-phase circuit of the double circuit heterogeneous submarine cable is calculated by the MATLAB

and the electromagnetic thermal current multi-physical-field coupling simulation model of the double-circuit heterogeneous submarine cable temperature distribution is established by finite element simulation software with current as the coupling term. The current-carrying capacity and temperature changes of the double-circuit heterogeneous landing section submarine cable considering the effect of circulation are studied

and an optimization scheme for the landing section current-carrying capacity considering both environmental heat dissipation conditions and internal circulation losses is proposed. The research results indicate that the simulation model considering the overall line circulation has higher computational accuracy compared to traditional simulation

and the maximum error can be reduced from 9.47% to 0.63%. When the air velocity is greater than 0.5 m/s

the convective heat flux in the cable trench of the landing section tends to saturate

causing the overall trend of the cable's current-carrying capacity and insulation temperature difference to first increase sharply and then stabilize. When adopting the optimization scheme of reducing circulation by adding seawater

the current-carrying capacity of oil filled submarine cables and XLPE submarine cables can be increased by 49.9% and 49.6%

respectively. This study can provide reference and ideas for the calculation of current-carrying capacity and engineering laying of landing section submarine cables.