Dynamic thermal rating of thermal risk sections in submarine cables transmission lines under the diurnal variation of solar radiation

To solve the problem that the current carrying capacity of submarine cable is underestimated due to ignoring the daily variation of solar radiation and the thermal inertia of cable in the existing steady-state thermal assessment model, a dynamic thermal assessment method of J-tube section cable with periodic solar radiation characteristics is proposed in this paper. Based on the lumped element method, the real-time thermal network model of J-tube section cable is constructed, and the solar radiation diurnal variation model is introduced to dynamically analyze the influence of time-varying heat flow boundary conditions on the cable temperature field. The periodic heat flux of solar radiation is used as the boundary condition to realize the dynamic prediction of cable conductor temperature. The comparative calculation results show that compared with the traditional steady-state method, the dynamic model proposed in this paper can effectively characterize the conductor hot spot temperature lag effect caused by thermal inertia; especially under typical adverse conditions such as high temperature and low wind, the predicted value of cable ampacity increased by >10%. This work establishes a theoretical framework for optimizing submarine cable cross-sections and ensuring operational safety, and has significant engineering application value for improving the efficiency and economy of renewable energy transmission.