Active Power Control on wind turbines: impact on mechanical loads

Abstract

This work focuses on the evaluation of how ActivePower Control (APC) impacts the mechanical loads of a utility-size Wind Turbine (WT). Two APC strategies, each with four levels of power reserve, are considered and compared. The assessment is numerically performed over the 5 MW WT benchmark model. Fatigue analysis is carried out under realistic wind profiles and following IEC 61400-1 standard. Extreme load analysis is performed as well, with extreme wind conditions as defined in the standard, and with a statistical load extrapolation from normal wind conditions. The assessment is repeated with both a Linear Parameter-Varying controller and a gain scheduling Proportional Integral controller comprising 3225 simulations. Interesting results are obtained about how APC affects mechanical loads, and how this impact changes according to the control strategy applied. For instance, for some combination of controller scheme and APC strategy, fatigue loading is reduced with respect to maximum power tracking without increasing extreme loads.These results lead to the conclusion that fatigue load can be improved by unevenly distributing power reserve among wind turbines across the wind farm.