Integrating detailed power take-off system models in wave energy converter simulations using an FMI-based co-simulation approach

Journal article, 2025

The power take-off (PTO) system is a core component of a wave energy converter (WEC) that significantly in-fluences its power performance. Careful design and testing of PTO systems are essential in WEC development. Numerical simulations have largely replaced physical testing, accelerating the PTO system design process. How-ever, one major obstacle still prevents numerical modelling of the PTO system from achieving its full capability: integrating the PTO system model into the global simulation of the WEC system to include the effects of all sub-systems. This paper uses a co-simulation approach based on the Functional Mock-Up Interface (FMI) standard to integrate a detailed PTO system model into a global WEC model that includes hydrodynamic, mechanical, and mooring subsystems. The approach is compared against a model incorporating a simplified linear-damper PTO system. The results indicate that a higher-fidelity PTO system model can have a significant impact on predictions of WEC motion, mooring fatigue damage accumulation, and power performance. For example, it is observed that a simplified PTO model can lead to a tenfold underestimation of mooring fatigue damage under some environ-mental conditions.