ABSTRACT

A reliable simulation model to calculate the motion and force responses of wave energy converters (WECs) is imperative to ensure the reliability and long-term performance of WEC systems; these aspects are fundamental to achieving full commercialisation of wave energy. A simulation model was developed and validated concerning the simulated WEC buoy motions in a previous study; this study validated the mooring force calculations for the same model. The example WEC system comprises a buoy, a power take-off (PTO) system, and a three-leg mooring system wherein each leg is divided into two taut segments joined by a submerged float. A 1:20 physical model was built and tested in the Deepwater Offshore Basin at Shanghai Jiao Tong University. Numerical models were developed to simulate the coupled hydrodynamic and structural responses of the WEC system, primarily using potential flow theory, the boundary element method, the finite element method, and the Morison equation. The simulated and measured axial force results at the top ends of the six mooring segments were compared; the results agreed best in the lower segments of each mooring leg and in the moorings on the downwind side because of the PTO system uncertainties and the uncalibrated damping in the numerical model. Nonetheless, the numerical model reasonably predicted the moorings’ accumulated fatigue damage, demonstrating that the model can be reliably used for mooring structural analyses. The study also used the validated numerical model to simulate a full-scale WEC system installed in Runde, Norway. A comparison of the results from the full-scale measurements and simulations shows that the numerical simulation model exhibited a good predictive capability for the mooring forces of the full-scale WEC system.

摘要

必须有一个可靠的仿真模型来计算波能转换器（WEC）的运动和力响应，以确保WEC系统的可靠性和长期性能。这些方面是实现波浪能完全商业化的基础。在先前的研究中，针对仿真的WEC浮标运动开发了仿真模型并进行了验证；这项研究验证了相同模型的系泊力计算。示例WEC系统包括浮标，取力器（PTO）系统和三腿系泊系统，其中每条腿被分成两个由水下浮标连接的拉紧段。在上海交通大学深水近海盆地建立了1:20物理模型并进行了测试。开发了数值模型来模拟WEC系统的水动力和结构响应耦合，主要使用势流理论，边界元法，有限元法和莫里森方程。比较了六个系泊段顶端的模拟和测量的轴向力结果。由于PTO系统的不确定性和数值模型中未校准的阻尼，结果在每个系泊腿的下段和顺风侧的系泊中的结果最佳。但是，该数值模型可以合理地预测系泊的累积疲劳损伤，表明该模型可以可靠地用于系泊结构分析。这项研究还使用经过验证的数值模型来模拟安装在挪威Runde的全尺寸WEC系统。