WP3 constitutes the main effort towards achieving SO2. The main objective is to develop novel load analysis techniques, to allow characterizing and reducing the uncertainties which are constituents of the reliability computations for ultimate and fatigue designs in WP4 and WP5. In contrast to WP2 where the focus is purely on the environment on kilometre scales down to wind farm scales, WP3 introduces the wind farm in the landscape and focuses on the phenomena taking place within a wind farm and down to turbine level due to their interactions with the environment. This includes realistic modelling of wake interactions, structural response of wind turbines to aerodynamic and hydrodynamic loading under stationary conditions, and the effect of transient events on wind turbine loads.
In the design practice, the effect of wake interactions on wind turbine loads is typically assessed using engineering models for simulating wake disturbances. HIPERWIND quantifies the uncertainty of commonly used engineering models (FLORIS2 , TOPFARM, DWM, FarmShadow) by comparing them with coupled high fidelity aeroelastic and LES simulations. To enable efficient uncertainty propagation, the effect of wakes needs to be parameterized with a few variables which can serve as input to surrogate models (Dimitrov, N.(2019) Surrogate models for parameterized representation of wake-induced loads in wind farms, Wind Energy 22 (10), pp.1371-1389).
HIPERWIND will test different wake parameterizations and quantify the uncertainty associated with them. The modelling of wake effects for floating wind turbines presents an additional challenge due to the motion of the platform, however this also presents opportunities for reduction of wake disturbances as the platform mean pitch will result in upward wake deflection4,5 . In HIPERWIND, the effect of static deflection and low frequency motion of the floating platform on the wake interactions is considered by means of coupling a wake simulation model with a hydrostatic solver.
Proper modelling of the wind field describing transient events is of critical importance for design load evaluation as the shape and magnitude of the transient can significantly affect the peak loads. This is tackled in WP3 by directly introducing measured time series of transient events in the turbulence fields through the constrained simulation approach6 .
Finally, the model uncertainty in representing the aerodynamic and the hydrodynamic interactions at the turbine scale are estimated. The resulting model uncertainty and loading conditions are transferred to WP4 and WP5 for reliability estimate of the turbine components.