Wind farm sites within complex terrain are subject to local wind phenomena, which are difficult to quantify but have a huge impact on a wind turbine's annual energy production. Therefore, a wind sensor was applied on an unmanned aerial vehicle and validated against stationary wind sensors with good agreement. A measurement over complex terrain showed local deviations from mean wind speed of approx. ± 30 %, indicating the importance of an extensive site evaluation to reduce investment risk.
Wind farm sites within complex terrain are subject to local wind phenomena, which are difficult...
Review status: a revised version of this preprint was accepted for the journal WES and is expected to appear here in due course.
Wind speed deviations in complex terrain
Christian Ingenhorst1,3,Georg Jacobs1,Laura Stößel2,Ralf Schelenz2,and Björn Juretzki3Christian Ingenhorst et al.Christian Ingenhorst1,3,Georg Jacobs1,Laura Stößel2,Ralf Schelenz2,and Björn Juretzki3
Received: 31 Jan 2020 – Accepted for review: 09 Mar 2020 – Discussion started: 17 Mar 2020
Abstract. Wind farm sites within complex terrain are subject to local wind phenomena, which have a huge impact on a wind turbine's annual energy production. To reduce investment risk, an extensive site evaluation is therefore mandatory. Stationary long-term measurements are supplemented by CFD simulations, which are a commonly used tool to analyse and understand the three-dimensional wind flows above complex terrain. Though being under heavy research, such simulations still show a huge sensitivity for various input parameters like terrain, atmosphere and numerical setup. Within this paper, a different approach aims to measure instead of simulate wind speed deviations above complex terrain by using a flexible, airborne measurement system. An unmanned aerial vehicle is equipped with a standard ultrasonic anemometer. The uncertainty of the system is evaluated against stationary anemometer at different heights and shows very good agreement, especially in mean wind speed (< 0.12 ms−1) and mean direction (< 2.4°) estimation. A test measurement was conducted above a forested and hilly site to analyse the spatial and temporal variability of the wind situation. A position dependent difference in wind speed increase up to 30 % compared to a stationary anemometer is detected.
Wind farm sites within complex terrain are subject to local wind phenomena, which are difficult to quantify but have a huge impact on a wind turbine's annual energy production. Therefore, a wind sensor was applied on an unmanned aerial vehicle and validated against stationary wind sensors with good agreement. A measurement over complex terrain showed local deviations from mean wind speed of approx. ± 30 %, indicating the importance of an extensive site evaluation to reduce investment risk.
Wind farm sites within complex terrain are subject to local wind phenomena, which are difficult...