Wake steering experiments in onshore and offshore wind farms

Over the past years, wake steering has been the subject of much research in the wind industry. Multiple academic publications have shown results from high fidelity simulations (such as SOWFA), engineering simulations (such as FLORIS) or from field tests. Most of this research is focused on the power increase as it is the main goal of wake steering. However, other key topics need to be covered upfront. Wake Adapt is the product developed by Siemens Gamesa Renewable Energy that applies wake steering at commercial level. As presented in this paper, some prerequisites are needed before Wake Adapt installation to ensure the wind turbines are calibrated to apply the optimum yaw offsets. The increase in energy is not without costs: yaw activity is increasing which impacts the maintenance costs. Wake Adapt loads must be assessed, and it has been shown that Wake Adapt loads cases are covered by design loads of the turbines. On the modelling side, the Wake Adapt yaw offsets are generated using some engineering models well known by the scientific community. Some robustness is added to the Yaw Offset Lookup Table to ensure that the optimum yaw offsets calculated in steady-state conditions are still optimum with unsteady conditions. Finally, in order to measure the Wake Adapt benefit, a Swap Test can be conducted where wind farm power output with and without Wake Adapt are compared following a certain procedure, especially if the predicted and measured power benefit needs to be compared. The last section of this paper shows some first tests in an onshore wind farm, as well as the results of a full Swap Test in an offshore wind farm, where the measured gain and the predicted gain shows very similar values.