高压直流海底电缆电–热–流多物理场耦合仿真

Coupled Simulation on Electro-thermal-fluid Multiple Physical Fields of HVDC Submarine Cable

高压直流电缆运行时径向温度和电场分布是反映其运行状态的重要参数,考虑流场的海底电缆电热耦合规律研究具有重要意义。依据南澳直流工程±160 kV高压直流海底电缆,利用COMSOL Multiphysics有限元分析软件,建立了海缆本体及其敷设环境的3维电–热–流耦合模型,以控制变量法研究了铺设和埋设2种敷设方式下海缆载流量、海水温度和海水流速对海缆径向温度和电场分布的影响。结果表明:载流量是海缆径向温度和电场分布的主要影响因素;在该模型下海缆导体温度和绝缘层温差与海水温度存在线性关系;很小的海水流速能显著降低海缆温度,因此提出静止海水散热的流速修正系数;海水流动有利于海缆散热,导致海缆温度分布发生变化,同时影响海缆绝缘材料电导率而导致电场分布发生改变。

Distribution of radial temperature and electric field is an important parameter to reflect the operation state of high-voltage direct-current（HVDC） submarine cables, and it is of great significance to study the electro-thermal coupling law of submarine cable considering fluid field. According to the ：t：160 kV HVDC submarine cable of Nan＇ao project, a three-dimensional （3D） electro-thermal-fluid coupling model of the submarine cable and its laying environment were set up by using the COMSOL Multiphysics finite element analysis software. By using the control variable method, the im- pacts of ampacity, seawater temperature, and seawater velocity on the radial temperature and electric field distribution of the submarine cable were analyzed by two kinds of laying methods including laying and burying. The results indicate that the ampacity is the main influencing factor of radial temperature and electric field distribution. Based on the model, it is found that the submarine cable conductor temperature and insulation temperature difference both have linear relationship with seawater temperature. Tiny seawater velocity can significantly reduce the temperature of the submarine cable, thus a seawater velocity correction factor of static seawater heat dissipation is proposed. The flow of seawater is beneficial to the heat dissipation of the submarine cable, which results in the change of the temperature distribution of the submarine cable. Furthermore, the flow of seawater will affect the electrical conductivity of the submarine cable insulation material to change the electric field distribution.