Effect of Mechanical Strain on Water Treeing Mechanism of Dynamic Cable for Floating Offshore Wind Applications

海上风能是英国向可持续未来电网过渡的雄心的核心。来自浮动风力涡轮机的发电的增长越来越远离海岸并且利用浮动风力涡轮机支撑结构。这增加了电缆所承受的机械应变，而潮汐和波浪运动引起的使用中振荡运动进一步增强了机械应变。电缆结构中的低频物理振荡是否会造成固有的可靠性风险尚不清楚，因为传统的陆地电缆通常安装在相对良性的环境中。通常，电缆资产占海上风电场总投资成本的5-10%。然而，电缆故障导致大多数海上停电，占该行业保险索赔的约80%。本项目将研究动态电缆中不同机械应变对水树机制的影响，并在代表性测试条件下模拟此类设计的老化。一个定制的水树试验台与不同的机械应变将开发和测试下不同的参数。首先将进行一系列小规模实验，以研究稳态和低频机械振荡对水树生长特征变化的影响。这是为了确定机械应变的循环是否加速水树的引发和生长过程。因此，潜在地增加了动态电缆的故障风险。

Offshore wind energy is central to UK's ambition of transitioning to a sustainable future electricity grid. The growth in power generation from floating wind turbines are increasingly further away from shore and utilising the floating wind turbine support structures. This increases the mechanical strain the cable is subjected to, which is enhanced further by in-service oscillatory movement caused by tidal and wave motion. It is unknown whether low frequency physical oscillations in cable structures pose an intrinsic reliability risk since conventional land cables are typically installed in relatively benign environments. Typically, cable assets contribute to 5-10% of the total investment costs for an offshore wind farm. However, cable failures cause the majority of the offshore power outages and account for approximately 80% of insurance claims in this industry. This project will investigate the effect of varying mechanical strain on the water treeing mechanism in dynamic cable and model the ageing of such design under representative test conditions. A bespoke water treeing test rig with varying mechanical strain will be developed and to be tested under different parameters. A series of small-scale experiments will be initially carried out to investigate the impact of steady state and low frequency mechanical oscillations on the characteristic change in water tree growth. This is to determine whether cycling of mechanical strain accelerates water tree initiation and growth processes. Thereby, potentially increasing the risk of failure for dynamic cables.