Estimates of Maximum Design Loads for a Whisper H40 Using Extrapolation Methods

摘要

The latest version of IEC61400-1 (Wind Turbine Generator Systems – Part 1: SafetyRequirements, 3rd Ed. Draft) now requires load extrapolation (from simulation results) be used topredict the overall maximum-lifetime loads. This approach has not yet been adopted for theIEC61400-2 standard (Safety of Small Wind Turbines). To date, there is minimal experiencewith this type of analysis on a small furling wind turbine. It is the goal of this study to betterunderstand the benefits and problems associated with extrapolation of either measured data orsimulated data as it pertains to small furling wind turbines. This will be accomplished using bothmeasured and simulated load and performance data from a Southwest Windpower Whisper H40wind turbine.Windward Engineering L.L.C., as part of a contract with DOE under the Field VerificationProgram for Small Wind Turbines, has installed two small furling wind turbines. One is locatedat the National Wind Technology Center (NWTC) near Boulder Colorado and the other at a testsite in Spanish Fork, Utah. The turbine located in Spanish Fork, UT has been operating almostcontinuously since February 2000. Originally only performance parameters were beingmonitored and logged. In the spring of 2002 load measurement capabilities were added formonitoring the blade root bending moment, as well as two tower bending moments. Since theload sensors were installed, a significant amount of data have been collected in normal winds,high winds, and extreme winds. Extrapolation techniques were applied to this data to estimatethe maximum expected loads during the turbines lifetime.This study will evaluate the sensitivity of the results to various parameters, including how thedata were sorted and processed. It will also evaluate how the predicted maximum expectedvalues compare to the highest loads measured during extreme wind events. Comparisons willalso be made between extrapolations from ADAMS model results and those from measured data.