Analysis and Verification of Wind Data from Ground-based LiDAR

Abstract

A study on the verification of reliability of measurements by the LiDAR (Light Detection and Ranging) system was conducted in Kimnyeong, on Jeju Island, South Korea. Also, the accuracy of the LiDAR measurements taken from the relatively flat-terrained Kimnyeong site was determined after factoring in the wind disturbance caused by the wake behind wind turbines. The 2.5-month wind data collected by the LiDAR were compared with concurrent wind data collected by the conventional anemometry on a nearby 120 m-high met mast for the verification. The measurement sectors (the area around the wind turbine where undisturbed wind speeds were measured) and the disturbed sectors (the areas around the wind turbine prone to wind disturbance) were estimated in accordance with the International Electrotechnical commission, IEC 61400-12-1. Data filtering was performed based on the criteria suggested by previous research. As a result, at 116 m above ground level, comparatively high LiDAR error rates of 0.50∼12.69 % were found in the disturbed sector, while relatively low LiDAR error rates of -0.93∼4.26 % were shown in the measurement sector. In the measurement sector, the absolute values of LiDAR error rates were about 5 % with the standard deviations of about 5 % at the heights of 100 and 116 m above ground level. The power law exponents calculated by using the met mast and the LiDAR data collected from the measurement sector were very similar to each other, whereas met mast and LiDAR data collected from the disturbed sector showed major discrepancies.