Posters

Abstract

Turbine siteability assessments using current standards and best practices, is observed to be the biggest gap that needs bridging when deploying Stand-alone LiDARs, simply because Wind LiDARs and anemometers on Met. Masts measure turbulence differently, and the today's best practices rely heavily on the latter. To bridge the gap, a novel method to arrive on a Met. Mast Equivalent was proposed and discussed, Bandpass Adjusted Turbulence method (BAT) [1]. The method in simple terms is a controlled frequency-based damper, which works on the systemic variations observed in 10-min measurement data scale across many sites across the world where a LiDAR and Met. Mast is measuring concurrently and is collocated. It was observed through the above validatory process that, on broader strokes, LiDAR measures a higher turbulence and turbulence spread as compared to a Met. Mast and a Large-scale validation of the method showed that the BAT method estimates turbine siteability closer to a Met. Mast and bridges the discrepancy with LiDAR measurements [2]. However, it was also observed [2] that though largely it is true that LiDAR over-estimates turbulence and its spread on most of the terrain characteristics, but in Flat terrain LiDAR under-estimates turbulence, which also aligns with previous research and literature [3]. It can be conjectured whether this is being observed in the Flat terrains as most of LiDAR vs Met. Mast or LiDAR vs flow model research has been done on Flat terrains where the control environment for models is easier implemented. Nevertheless, this maybe a serious concern, looking from the turbine siteability aspect, as with a stand-alone LiDAR, the turbines may stand to be under-conservative when evaluated with LiDAR measurements only. Thus, there is a clear need for a Flat terrain specific BAT model, i.e. a BAT model trained with LiDAR and collocated, concurrent Met. Mast only on Flat terrain - hereon referred to as Flat BAT. This research article focuses on the Flat BAT and its validations on several flat sites. It is observed that through Flat BAT the turbine siteability becomes conservative, getting much closer to the siteability assessment from Met. Mast measurements. Alongside presenting the validations, the research also dives deeper to highlight the BAT transformation from the respect of turbulence spread, which is necessary to bridge the observed under-estimation of turbulence through LiDAR, and as a process also to give confidence to the turbine siteability assessments that stand-alone LiDAR in Flat terrain, which is perceived as one of the lesser challenges, does not yield under-conservativeness to the turbine selection and loads evaluation. This methodology in general and also its different parts are being actively researched and discussed in several different forums, including Site Suitability Sub-group of the Consortium For Advancing Remote Sensing (CFARS). 1. WindEurope Tech Workshop, 2022. https://windeurope.org/tech2022/proceedings/posters/PO067/ 2. WindEurope Annual Event 2023. https://windeurope.org/annual2023/conference/posters/PO166/ 3. Sathe, A., Mann, J., Vasiljevic, N., & Lea, G. (2014). A six-beam method to measure turbulence statistics using ground-based wind lidars. Atmospheric Measurement Techniques Discussions, 7, 10327-10359. https://doi.org/10.5194/amtd-7-10327-2014