Abstract
A comparative exercise for estimating the uncertainty associated with new methods for power performance measurements was coordinated by the International Energy Agency (IEA) Wind Task 32. Both IEA Task 32 and the Power Curve Working Group (PCWG) have identified the application of the new uncertainty guidelines as a problem area. One time series dataset from a wind turbine, hub height mast and vertical profiling lidar was provided to calculate the power curve using three different wind speed definitions. For each wind speed definition, participants had to estimate the wind speed measurement uncertainty based on the guidance provided by the June 2016 Final Draft International Standard (FDIS) of IEC 6140012-1 Edition 2. The comparative exercise included three iterations over the course of one year to incrementally harmonize the calculations and assumptions. The exercise showed significant variability among participants reflecting difficulty with the interpretation and application of the informative guidance. It also demonstrated that when using current technology and the available calibration techniques the use of a standalone lidar with a short met mast resulted in a significantly higher uncertainty compared to only using a hub height mast (with some measurements of wind shear and wind veer in the lower rotor).
Highlights
The method for calculating a wind turbine’s power curve using a Rotor Equivalent Wind Speed (REWS) was previously evaluated in a comparative exercise [1] coordinated within International Energy Agency (IEA) Wind Task 32
For the purpose of this exercise, there was a limited focus applied to differences in the power curve and Annual Energy Production (AEP) as a result of the different wind speed definitions
The low standard deviations values for Wind Speed 1 (WS1) and Wind Speed 2 (WS2) suggest that a good consensus was found among participants
Summary
The method for calculating a wind turbine’s power curve using a Rotor Equivalent Wind Speed (REWS) was previously evaluated in a comparative exercise [1] coordinated within International Energy Agency (IEA) Wind Task 32. The focus of the exercise was the application and impact of using a REWS versus a Hub-Height Wind Speed (HHWS) under various inflow conditions using existing datasets. The scope of the exercise did not require an estimate of the measurement uncertainty but it did show variation in the application or interpretation of applying a REWS. In March of 2017, IEC 61400-12-1 Edition 2 [6] was released which included the option to apply REWS for power performance measurements and guidance for how to estimate the REWS uncertainty. For the purpose of this exercise, there was a limited focus applied to differences in the power curve and Annual Energy Production (AEP) as a result of the different wind speed definitions. The focus was comparing the measurement uncertainty both in the binned power curve and for the estimated AEP values. It should be considered that some variation in the uncertainty was expected
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