摘要
随着全球对环境保护和可再生能源的重视，清洁能源发电得到了前所未有的发展，其中一个重要的方面便是海上风力发电，我国风力发展‘十三五’规划提出要积极稳妥推进国内海上风电建设。同时，为了增强离岸岛屿的供电可靠性，近年来我国兴建了多项海底电缆输电工程。在这些跨海输电工程中，海底电缆作为连接两端变电站或换流站的重要设备，起到了关键作用。海底电缆结构复杂、制作工艺要求高，其使用环境特殊，深入海底，监测与检修也极为不方便，国内外均没有海底电缆载流量计算的规范或标准。因此，为确保海底电缆安全可靠运行，有必要开展海底电缆载流量分析计算。
论文构建了海底电缆软、硬接头物理模型，建立了电缆电磁-热耦合场数学模型，采用有限元法进行了海缆软、硬接头的温度特性分析和不同敷设方式下海缆的载流量计算。具体研究内容主要包括：
①分析了海底电缆的不同敷设方式。以电磁场理论和温度场传热学基本定律和方程为基础，研究了电缆电磁-热耦合场数学模型，分析了海底电缆运行过程中的电磁场和温度场之间的相互作用耦合机理和求解步骤；通过理论计算和试验测试结果与仿真结果的对比，导体损耗密度的误差、海缆缆芯温度的误差均小于5%，验证了建立模型和仿真方法的有效性；
②利用COMSOL-Multiphysics软件建立了三维海底电缆接头的电磁-热耦合模型，对110kV海底电缆的软、硬接头分别进行了温度场分析与计算；研究了负荷电流对海缆软接头温度特性的影响规律；考虑了
海缆硬接头压缩金属连接头接触电阻的影响，分析了海缆硬接头不同接触系数对其温度的影响；
③进行了110 kV交流海缆直埋敷设、海水中敷设和登陆段排管敷设三种情况下的温度场及载流量的计算，分析了埋设深度、土壤热阻率和海水温度对海缆载流量大小的影响；分析计算了±500kV直流海底电缆常规直埋敷设和紧凑型敷设的温度场及载流量，对外部强制冷却对紧凑型敷设高压直流海缆载流量的提升进行了验证。
关键词：海底电缆，软接头，硬接头，有限元法，温度分布
ABSTRACT
With the global emphasis on environmental protection and renewable energy, clean energy generation gets an unprecedented development, one of the important aspects is the offshore wind power. China's wind development 'thirteen five' plan to actively and steadily promote the domestic offshore wind power construction, the development of offshore wind power will also lead to more submarine cable engineering applications, because the grid integration of offshore wind power will rely on submarine cable. At the same time, in order to enhance the reliability of offshore island power supply, China has carried out a number of large-scale submarine power cable transmission projects in recent years, such as Hainan 500kV AC submarine cable grid integration project, Zhejiang Zhoush
an, Fujian Xiamen and Guangdong Shantou HVDC transmission technology projects etc. In these cross-sea power transmission projects, submarine power cables work as the main device connecting at both ends of substations or multi-terminal converter stations, played an extremely important role. Submarine power cable has complex structure, extremely high production process requirements and comprehensive electrical and mechanical performance requirements. And its operating environment is much worse than the terrestrial cable, inconvenient for monitoring and maintenance. Besides, there are no specifications or standards for submarine cable ampacity calculations worldwide. In order to ensure the safe and reliable operation of the submarine power cable, it is necessary to carry out submarine power cable ampacity analysis and calculation.
The purpose of this thesis is to analyze and calculate the temperature field distribution and submarine cable ampacity under different flexible and rigid joint connections. Power cable flexible and rigid joint - respectively, refers to the connector at the cable conductor connection using welding and crimp connection. Most of the existing power cable ampacity calculation is based on IEC-60287 standard using thermal analysis or temperature field numerical calculation. Most of the temperature field is calculated on the cable body cable core, without considering the impact of cable joints. And due to poor production process or production operation is not standardized of cable intermediate join
t, joint conductor's contact resistance can be unusually high which cause uneven heating to the insulation will lead harm to the power cable.
In this thesis, the structure model of flexible and rigid joints of submarine power
cable is constructed, and the mathematical coupling model of the electromagnetic field and temperature field of the submarine power cable joint is established. The finite element method is used to analyze the temperature distribution of the submarine power cable joints and the calculation of the ampacity of the submarine cable. It is of great practical significance to make the load plan of the cable operation department and ensure the safe and reliable operation of the submarine power cable. The main research contents of this thesis include:
①The different laying methods of submarine cables are analyzed. And based on the theory of cable electromagnetic field and the basic law and equation of temperature field and heat transfer, the mathematical model, control equation and boundary condition of electromagnetic - thermal coupling field are studied. The coupling mechanism and solving steps of the interaction between the electromagnetic field and the temperature field during the operation of the submarine cable are analy
zed. The validity of the model is verified by comparing the theoretical and experimental results with the simulation results.
②The COMSOL-Multiphysics software was used to establish the 3-Dimensional electromagnetic-thermal coupling model of the flexible joint and rigid joint of the 110kV submarine cable, respectively. The temperature field analysis and calculation of two joints are also carried out respectively. Based on these models, the influence of load current on the temperature characteristics of submarine cable joints are studied. And the influence of the contact resistance of crimp connector on the temperature field of the cable rigid joint is analyzed. All these work will contribute to the approving of the submarine cable ampacity.
③Calculated the temperature field and ampacity of 110 kV AC submarine cable, which was laying in 3 methods-underwater soil buried laying, laying in seawater and laying in the pipeline in landing section of the cable. The effects of embedding depth, soil thermal resistivity and seawater temperature on the ampacity of the submarine cable were analyzed, respectively. Finally, Calculated the temperature field and ampacity of±500kV DC submarine cable in soil buried laying and compact laying method, verificated the ampacity enhancement of external forced cooling.
Keywords:Submarine Power Cable, Flexible Joint, Rigid Joint, Finite Element Method,Temperature Distribution
目录
目录
中文摘要.......................................................................................................................................... I 英文摘要....................................................................................................................................... III 1 绪论.. (1)
1.1 论文的背景及研究意义 (1)
1.2 国内外研究现状 (3)
1.3 本文主要研究内容 (5)
2 海底电缆电磁-热耦合模型 (7)
2.1 海底电力电缆结构与敷设方式 (7)
2.1.1 海底电缆结构 (7)submarine
2.1.2 海底电缆敷设方式 (8)
2.2 电缆电磁-热耦合场数学模型 (10)
2.2.1 电缆电磁场数学模型 (10)
2.2.2 电缆温度场数学模型 (12)
2.3 电缆电磁-热耦合作用与求解 (12)
2.4 计算实例与模型有效性验证 (14)
2.5 本章小结 (17)
3 海底电缆软、硬接头温度场分析与计算 (19)
3.1 高压交流海底电缆接头结构 (19)
3.1.1 海底电缆软接头 (19)
3.1.2 海底电缆硬接头 (20)
3.2 高压交流110kV海底电缆软接头的温度场计算模型 (21)
3.2.1 边界条件确定 (23)
3.2.2 网格剖分 (24)
3.2.3 计算结果与分析 (24)
3.3 高压交流110kV海底电缆硬接头的温度场计算模型 (27)
3.3.1 海缆硬接头接触电阻分析 (28)
3.3.2 计算结果与分析 (30)
3.4 本章小结 (34)
4 交流海缆温度场分析与载流量计算 (35)
4.1 高压交流海底电缆直埋敷设温度场及载流量计算 (35)
4.1.1 高压交流110kV海底电缆物理几何模型 (35)
4.1.2 边界条件确定 (36)
4.1.3 网格剖分 (37)
4.1.4 计算结果与分析 (38)
4.2 高压交流海底电缆海水中敷设温度场及载流量计算 (43)
4.2.1 海水中敷设及物性参数 (43)
4.2.2 计算结果与分析 (43)
4.3 高压交流海底电缆登陆段排管敷设温度场及载流量计算 (45)
4.3.1 登陆段排管敷设及物性参数 (45)
4.3.2 计算结果与分析 (46)
4.4 本章小结 (47)
5 高压直流海底电缆温度场及载流量计算 (49)
5.1 ±500kV高压直流海缆温度场及载流量计算 (49)
5.1.1 ±500kV高压直流海底电缆物理几何模型 (49)
5.1.2 ±500kV高压直流海底电缆敷设情况及建模 (50)
5.1.3 计算结果与分析 (51)
5.2 外部强制冷却对紧凑型敷设高压直流海缆载流量的提升 (54)
5.3 本章小结 (55)
6 结论和展望 (57)
6.1 研究工作结论 (57)
6.2 后续工作展望 (58)
致谢 (59)
参考文献 (61)
附录 (65)
A 作者在攻读硕士学位期间科研成果 (65)
B 作者在攻读学位期间参加的科研项目 (65)

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