Field Test, Dynamic Simulation and Fatigue Analysis of a Small Wind Turbine Operating in a Highly Turbulent Environment

Abstract

A performance test, aero-structural simulation and fatigue analysis was done on a 135 W SWT (small wind turbine) in a turbulent environment. The results showed an increase in average power output with increasing turbulence intensity (TI), and this was more pronounced at TI values above 25%. The increase in power was more pronounced at higher wind speeds (>7 m/s). A FAST model was used for simulation. There was a good correlation between the FAST model and field test, and the error was never more than 20% for lower wind speeds and 8% for higher wind speeds. NREL Turbosim, FAST and Crunch were used to run the dynamic simulations and rainflow counting for the GFRP (glass fibre-reinforced polymer) blade fatigue DEL (damage equivalent load) evaluation. It was found that the fatigue root MOOP (moment out-of-plane) DEL for this particular site was more than double that of IEC NTM (normal turbulence model) Class C wind for most of the wind speeds. The root MIP (moment in plane) did not change regardless of the turbulence intensity; however near higher wind speeds, the frequent cut-out of the machine caused an increase in root MIP DEL.