The key part of the technology validation was a 1:10 scaled demonstrator which was tested in two project phases in different environments. A fully functional 1:10 scale model based on Froude was designed, manufactured and assembled for this purpose. The challenge was to implement the components in the scaled weight, otherwise the measurement results would not have been usable. At the same time, original materials such as concrete, steel and carbon ropes were used and the planned assembly process was implemented. The nezzy² foundation was assembled onshore with the help of a lifting tower.
In the first phase of the project in a quarry lake in northern Germany, the focus was on aerodynamic validation, buoyancy, electronics and the calibration of the individual sensors. Due to the lack of waves and lack of current, the demonstrator was actually only exposed to the wind, which was quite turbulent and constantly changed direction. Two-blade rotors and three-blade rotors were tested, the wind tracking was measured, the load flow from the turbine thrust to the anchor line was tracked and generated in different operating situations. The global behavior of the structure coincided with the previous tests and the design assumptions, and the structural loading due to the dynamic behavior showed lower loads than assumed.
All power electronics were calibrated and various control algorithms, in particular the yaw control, could be tested using the in-house developed system controller.
The demonstrator was equipped with over 180 sensors and measurement channels, so that both the environmental conditions and the behavior of nezzy² were measured. The collected data was evaluated and compared to the design assumptions and simulations. For the first project phase validation, the measurement data matched the simulation data very well.