Posters

Abstract

Procurement processes for wind turbines following site assessment and micorsiting are commonplace. Indeed, so are the installation methods which culminate in trial-runs of roughly 180 hours/WTG. Still, customers are not particularly concerned with designs and materials, they are however especially interested in real power curves. They are after all acquiring the relationship between wind resource and generated MWh. Given the huge capacities of new platforms this is becoming ever so urgent, and interestingly, there is no widespread practice for verifying every single turbine's power curve during commissioning, prior to takeover and final payment to OEMs. This is not due to lack of demand, but rather due to the limitations of contemporary wind measurement instruments, namely wind masts and LiDARs. The commissioning period for an average-sized wind farm takes up to 3 months at which point the last turbine completes its trial runs. If we were to run power curve verifications for each turbine we would ideally, and according to IEC standards (1) collect three or more 10-minute samples for each wind bin until the wind speed at which the generator is producing at full capacity and (2) measure within distances of 2-4 diameters, upwind, and in unwaked sectors. Given the sizes of new wind farms and the stationary nature of wind masts, these do not even remotely qualify, and neither do LiDARs. Even if the latter are nacelle-based, transporting them from turbine to turbine via crane and then calibrating them on each nacelle is logistically and economically unviable: Within the said period LiDARs could practically performance-test a single turbine, possibly two. The critical variable is seamless mobility which in turn enables tailored, direct measurement for all WTGs within a relatively short period of time. Enter drone-based wind measurements: case in hand - Windborne, a globally patented, validated, aircraft-deployed wind measurement instrument. The drone's mobility and positioning enables it to collect sufficient data and immediately move on to test the next turbine. Requirement #1 is entirely met with respect to measurement positions, and during commissioning, unlike during operations, turbines creating wake can be stopped. With Respect to requirement #2, experience shows that each turbine requires 2 to 3 days of measurement to sufficiently enable the construction of individual power curves. Eventually, with accepted uncertainties currently calculated at 1-2%, stakeholders receive the specific power curve for each installed turbine towards warrantee and operational considerations. Further notes on wind resource assessment applications: Drone based performance monitoring via the Windborne sensor has been introduced in recent years in large operating wind farms in Europe. This is mainly due to unprecedented wind farm coverage, resulting in attractive returns from rapid income recovery. This abstract now suggests the introduction of such a system prior to commercial operation, and indeed in the future also for pure site assessment: one such example is the perfection of flow models, micrositing, and energy assessments via direct measurement at planned WTG locations, then correlated to a single stationary wind mast or LiDAR.