Simulation of Operational Extreme Wind Conditions for Horizontal Axis Wind Turbines Based on IEC Standard
Abstract
The possibility of simulating deterministic extreme operational conditions for horizontal axis wind turbines based on the IEC 61400-1 standard in the WindEEE Dome at Western University was investigated. WindEEE has 60 fans (a matrix of 4 by 15 with 0.8m diameter each) on one of the walls to generate straight and sheared flows. These fans were controlled by their power set-points and by their adjustable Inlet Guiding Vanes (IGV) to generate the Extreme Operational Gust (EOG), positive and negative Extreme Vertical Shear (EVS), and Extreme Horizontal Shear (EHS) cases as per IEC 61400-1 standard to be further applied for testing a scaled 2.2 m Horizontal Axis Wind Turbine (HAWT). First, Computational Fluid Dynamics (CFD) simulations of the WindEEE test chamber were carried out in order to predict the fans setups for each of these extreme conditions. The experiments were then carried out using these settings and a comparison was performed between the resulting flow field time histories and the prescribed conditions from the standard. The results showed a successful simulation of these extreme conditions. The extreme conditions were then applied to investigate the power and load performance of the scaled HAWT. The results revealed that the unsteady shears had no significant impact on the overall power generation. EHS induced a significant twisting moment on the structure. The EOG has the most noticeable effect which highly depends on the operational tip speed ratio (TSR) of the wind turbine and the time duration of the event.