Field experiment for open-loop yaw-based wake steering at a commercial onshore wind farm in Italy

Bart M Doekemeijer,Jan-Willem Van Wingerden,Filippo Campagnolo,Stoyan Kanev,Federico Fioretti,Friedrich Wilts,Giancarlo Potenza,Bastian Salbert,Thomas Neumann,Simone Schuler,Fabio Calabretta,Johannes Schreiber,Sivateja Maturu,Carlo L Bottasso,Stefan Kern

doi:10.5194/wes-6-159-2021

Abstract

Abstract. The concept of wake steering on wind farms for power maximization has gained significant popularity over the last decade. Recent field trials described in the literature not only demonstrate the real potential of wake steering on commercial wind farms but also show that wake steering does not yet consistently lead to an increase in energy production for all inflow conditions. Moreover, a recent survey among experts shows that validation of the concept currently remains the largest barrier to adoption. In response, this article presents the results of a field experiment investigating wake steering in three-turbine arrays at an onshore wind farm in Italy. This experiment was performed as part of the European CL-Windcon project. While important, this experiment excludes an analysis of the structural loads and focuses solely on the effects of wake steering on power production. The measurements show increases in power production of up to 35 % for two-turbine interactions and up to 16 % for three-turbine interactions. However, losses in power production are seen for various regions of wind directions too. In addition to the gains achieved through wake steering at downstream turbines, more interesting to note is that a significant share in gains is from the upstream turbines, showing an increased power production of the yawed turbine itself compared to baseline operation for some wind directions. Furthermore, the surrogate model, while capturing the general trends of wake interaction, lacks the details necessary to accurately represent the measurements. This article supports the notion that further research is necessary, notably on the topics of wind farm modeling and experiment design, before wake steering will lead to consistent energy gains on commercial wind farms.

Highlights

Over the last few years, the concept of wake steering on wind farms has gained significant popularity in the literature (Boersma et al, 2017; Kheirabadi and Nagamune, 2019)
Since WTG 26 is not misaligned for wind directions lower than 230◦ and higher than 290◦, the normalized power production should equal 1.0, as reflected in the FLOw Redirection and Induction in Steady State (FLORIS) predictions
Around wind directions of 255 and 265◦, yaw misalignments are assigned to the turbine, expected to lead to a loss in its power production

Summary

Introduction

Over the last few years, the concept of wake steering on wind farms has gained significant popularity in the literature (Boersma et al, 2017; Kheirabadi and Nagamune, 2019). By choosing the right yaw misalignment, the wake formed by an upstream turbine can be directed away from a downstream turbine at the cost of a small reduction in its own power production and a change in mechanical loads on the turbine structure. This concept enables a net increase in the power production of downstream turbines and, generally, of wind farms. The scope of this article is limited to the effects of wake steering on power production

Methods

Results

Conclusion