Posters

Abstract

Assessing Annual Energy Production (AEP) changes due to aerodynamic upgrades on wind turbines is challenging due to the inherent variation in wind conditions and uncertainties in nacelle anemometer measurements. Due to these reasons, the AEP change calculated directly by analysing the shift in the nacelle-windspeed-derived binned power curve before and after the upgrade often leads to incorrect performance assessments. The Side-by-Side (SbS) method, widely used in the wind energy industry, addresses these challenges by comparing the performance of an upgraded turbine with a reference turbine located nearby that remains unchanged. Since the turbines are located close to each other, the wind conditions seen by the turbines are similar, and further, most implementations of the SbS method have a minimal reliance on the nacelle windspeed measurements to assess the AEP changes. Thus, the effect of windspeed variation and uncertainties in the windspeed measurements is largely minimized when the SbS method is used.  One critical yet often overlooked factor affecting SbS assessments is data sampling frequency. Ideally, AEP uplift calculations should be consistent across sampling rates, reflecting the actual AEP change. However, a preliminary SbS analysis of aerodynamic upgrades in a wind farm revealed that datasets with shorter sampling intervals (e.g., 10 seconds) produced larger uplift estimates compared to coarser intervals (e.g., 10 minutes). For a particular reference - upgrade turbine pair, calculated AEP uplift varied from 1.43% to 0.14% as the sampling interval increased. The SbS method used in the analysis is inspired from the original SbS algorithm proposed in [1]. This variability suggests that some SbS implementations may exhibit sensitivity to sampling frequency, which has only been sparsely addressed in the existing literature. These findings highlight the importance of understanding and accounting for sampling rate effects to improve the reliability of SbS assessments. In this study, the results of uplift assessments obtained with datasets of different frequencies are presented for the case of aerodynamic upgrades in a wind farm. The presentation will discuss detailed results from the case study involving multiple upgrade – reference turbine pairs from the wind farm, and additionally, results obtained with another SbS tool – wind-up, a publicly available tool developed to calculate AEP assessments [2]. Additionally, it will explore potential causes for the observed discrepancies and propose mitigation strategies to enhance the accuracy and reliability of SbS analyses. By highlighting the importance of data resolution and performance evaluation, this work aims to contribute to refining best practices in the industry for power performance assessments of turbine upgrades. Keywords: Side by Side method, AEP uplift assessments, real-world case studies References [1] A. Albers; Relative and Integral Wind Turbine Power Performance Evaluation, Proceedings of EWEC 2004, London [2] https://github.com/resgroup/wind-up