考虑扭绞的三芯海底电缆温度稳态分布数值求解方法

Numerical Solution Method for Temperature Steady-state Distribution in Three-core Subma-rine Cables with Twisted Structure

三芯海底电缆是连接近海风电场与陆地电网的重要装置,其正常运行对于经济发展具有重要意义。导体温度与光纤温度的关系模型是温度分布式传感的理论基础,过去的研究未考虑光纤及电缆的扭绞对导体与光纤温度关系的影响。基于有限元法构建了考虑扭绞的三芯复合光纤海底电缆的电热流耦合模型,得到了导体温度与光纤温度的关系式,并分析了在埋设和铺设两种敷设环境下节距、海水温度、海水表面换热系数及不同电缆尺寸对导体及光纤温度的影响,以及对光纤与导体温度关系式的影响。仿真结果表明:在埋设的条件下,不考虑扭绞时,导体每上升1.03℃,光纤上升1.00℃;考虑扭绞时,导体温度及光纤温度均高于不考虑扭绞,随着节距的增大即扭绞角度变小,温度均下降,相同导体温度时,节距越大,光纤温度越低;铺设时海水的流动对于电缆的散热效果显著强于埋设时;对流换热系数越大,导体及光纤的温度越低;相同导体温度时,导体截面积越大,光纤温度越高。

The three-core submarine cable is an important device connecting offshore wind farms with land power grids,and its normal operation is of great significance to economic development.The relationship model between conductor temperature and fiber temperature is the theoretical basis of temperature distributed sensing,and the influence of twisting of optical fiber and cable on the relationship between conductor and optical fiber temperature is rarely taken into account in previous studies.Based on the finite element method,the electrothermal flow coupling model of three-core composite optical fiber submarine cable considering twisting is constructed,the relationship between conductor temperature and optical fiber temperature is obtained,and the effects of pitch,seawater temperature,seawater surface heat transfer coefficient and different cable sizes on the conductor and fiber temperatures under the buried and laying environment are analyzed.The simulation results show that,under the buried conditions,when the twisting is not considered,the conductor rises by 1.03℃,and the fiber rises by 1.00℃;moreover,when the twisting is considered,the conductor temperature and the fiber temperature are higher than those without considering the twisting;meanwhile,with the increase of the pitch,the twisting angle becomes smaller,and the temperature decreases;under the same conductor temperature,the larger the pitch is,the lower the fiber temperature will be.The flow of seawater during laying has a significantly stronger heat dissipation effect on the cable than that when buried.The larger the convective heat transfer coefficient is,the lower the temperature of the conductor and optical fiber will be.Under the same conductor temperature,a larger conductor cross-sectional area leads to higher fiber optic temperatures.