| 08 Dec 2025
Scaled testing of maximum-reserve active power control
Abstract. We present the scaled experimental validation of an active power control (APC) algorithm designed to optimize the tracking accuracy of a wind farm in the presence of turbulent wind lulls. This is obtained by maximizing the minimum local power availability (called reserve) across the farm. This method combines an offline-computed open-loop setpoint scheduler aimed at the power reserves, with a fast closed-loop corrector tasked with enhancing tracking accuracy. The open-loop component is synthesized using an augmented version of FLORIS, which models the combined effects of yaw misalignment and power curtailment, wind tunnel-specific inflow characteristics, and the influence of the chord-based Reynolds number (caused by the small size of the models) on the performance of the rotors.
A preliminary simulation-based steady-state analysis indicates that the approach effectively enhances local power availability across the wind farm by leveraging both induction and wake steering control. The methodology is then experimentally demonstrated in a large boundary-layer wind tunnel with minimal blockage, in different scenarios, including dynamically varying wind direction conditions. Its performance is benchmarked against three alternative APC strategies sourced from the literature. During the experiments, the APC algorithms run in real time on a dedicated cabinet and communicate with the turbine controllers via a dedicated network. Dynamic wind direction changes are generated using a large turntable driven by a field-recorded wind direction time series, scaled to match the temporal dynamics of the wind tunnel.
Results show that in both static and dynamic scenarios, the proposed control strategy outperforms the reference methods in power tracking accuracy, particularly under high power demand conditions, while maintaining a limited impact on structural fatigue. Notably, the algorithm effectively manages wake interactions and redistributes local power demands to increase local power reserves, thereby mitigating saturation effects and improving overall tracking performance.
Competing interests: Carlo L. Bottasso is the Editor in Chief of WES.
Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this paper. While Copernicus Publications makes every effort to include appropriate place names, the final responsibility lies with the authors. Views expressed in the text are those of the authors and do not necessarily reflect the views of the publisher.
The manuscript entitled “Scaled testing of maximum-reserve active power control” presents significant findings in the field of wind farm control. The paper is well written, with the objective and outcomes of the study clearly explained. However, there are some critical points that require further discussion:
- A deeper discussion of the timescale is needed: we know that time in the wind tunnel is accelerated and that the TI is 6%. Please discuss which real-world wind farm conditions this can represent.
- Explain how the real-time wind direction histories have been rescaled and adjusted for the experiment.
- The different controllers use bandpass frequency filters. Please explain how these frequency bands can be adjusted in real applications involving large multi-MW turbines.
- When discussing fatigue loads for single wind turbines in different scenarios, you should also analyse how these loads could affect the residual useful life of the entire wind farm and its maintenance programme.
- Figure 21 is crucial for understanding the various control strategies. Please improve it by adding more zoomed slices to make all the parameters clearer especially for highlighting saturation.