December 2013 - Recently Ecofys WTTS completed a - first of its kind – LiDAR & SoDAR cross verification measurements for Nuon/Vattenfall. Ecofys WTTS designed three tailored-made tests that consist of the investigation of the performance of their wind remote sensing fleet, used to execute wind resource assessments for wind farm developments in all kinds of terrains. The tests are centered on the IEC methodology (currently drafted in the IEC 61400-12-1 ed 2) and MEASNET standards, and are increasingly important for the traceability of the data, gaining terrain as a tool to decrease the uncertainties and gain confidence before and after every commercial wind measurement campaign. The tests consist of deploying remote sensing equipment to acquire wind data under carefully controlled conditions, and verifying its performance by means of comparing its wind speeds and wind directions measurements with the ones measured at an IEC-compliant reference Meteorological Mast. Ecofys WTTS’ Test Site is the largest onshore facility of its kind in Europe and its located in Lelystad, The Netherlands. The 120 meters high Met Mast was carefully designed to serve the needs of these tests and commissioned last June 2013. It includes over a dozen sensors distributed in four measurement levels between 40 and up to 120 meters, and the local winds are characterised by two large open valid sectors, one ranging from the north-west to south-west, and the second one towards the east.
Two different types of remote sensing instruments have been tested for Nuon/Vattenfall: one LiDAR and one SoDAR. Besides the individual verification analysis of each sensor against the reference, a third test called cross-check verification has been defined in order to compare the performance between the technologies themselves. The crosscheck test includes the verification of the shear, vertical wind speeds, turbulence levels, temperature, relative humidity and uncertainty differences between the technologies, which will help Vattenfall in its’ strategy for future technological investments and commercial decisions. The final test reports offer Vattenfall a set of characteristics raising their value: the tests’ intrinsic traceability to international standards, a full uncertainty assessment according to CD IEC61400-12-1, Ed.2 and a proof of the equipment’s readiness to serve as a stand – alone sensor for wind resource assessments.