Hydrodynamic Modeling of Tension Leg Platform Wind Turbines

In order to compute the system response of tension leg platform wind turbines (TLPWTs), it is important to accurately capture the hydrodynamic loading not only at the wave frequency, but also in the low (difference) and high (sum) frequency ranges. The current work compares the dynamic response of several single column TLPWT designs in different wind and wave conditions using three hydrodynamic models: first order potential flow with viscous drag, first and second order potential flow with viscous drag, and a Morison’s equation model. Second order wave forces were found to have a relatively small effect on the structural load predictions: increased tendon tension variation of approximately 2–10% was observed in storm conditions, while negligible effects were observed in operational conditions. The Morison model, however, gave significantly larger pitch forcing near the natural period, leading to larger structural load predictions in all sea states.