HYDRODYNAMIC MODELLING OF MEMBRANE FLOATS FLOATING PV SYSTEM IN OFFSHORE ENVIRONMENTS

In this study, the hydrodynamic responses of Membrane Floats Floating PV System in offshore environments were studied. The structure is modelled based on previous experiment of multi-tori structure by Jonathan Winsvold in 2018. The experiment significantly simplifies a complex membrane structure into sets of tori and truss structures, which were much easier to handle in both experiment and in numerical settings. Just like the Winsvold (2018) experiment, the continuous membrane is modelled as five discrete elastic tori that are connected by elastic trusses in the radial direction. The elastic truss elements have negligible inertia properties and their tension are configured to mimic the actual membrane stiffness. The experimental scale numerical model is validated against the experiment and theoretical results from literatures. Then, the full-scale structural diameter of 50 metres and torus cross-sectional diameter of 1.6 metres is modelled in the numerical setup. In this study, the load from Solar PV Modules were inserted as additional mass per length on the tori to better represent the real-world condition. To obtain better understanding of the hydrodynamic behavior of the membrane floats, two configurations of wire rope mooring systems and various membrane pre-tensions were simulated in the time domain. The mooring response and elastic behavior of the structure under various environmental load such as current and wave were also investigated. The wind loading is neglected in the present study, considering that the FPV has almost zero elevation. The sensitivity study results were then presented in the frequency domain. The simulation results suggested that mooring configuration significantly affected the structural response of the outermost part of the membrane, while has little to no effect on the innermost part of the membrane. The membrane's sensitivity to the change in elongation (i.e., pre-tension) shows that the model were also able to capture the increase of the membrane's apparent bending stiffness. Based on the results, the model may be used to provide further insight to improve future design of the membrane floats floating PV systems. The approach also opens up the possibilities of using a typical, more accessible, off-the-shelf rod or beam element-based FEM software to be used for simulating membrane type FPVs.