Investigation of the effects of individual pitch control of a wind turbine on loads, power and acoustic emission

Wind turbines have grown larger, causing their rotor blades to sweep across more extensive areas. As wind speed varies with height, the blades experience different loads during each rotation. Most modern turbines are equipped with individual pitch control (IPC) actuators to reduce loads. The acceptance of wind turbines by local communities is increasingly important, as are their acoustic emissions. Previous research found higher noise emissions when a modern turbine operates in IPC mode. This study analyzes the effects of IPC operation on power production, loads, and noise emissions. A modern multiMegawatt wind turbine is equipped with a measurement system to quantify loads, power and acoustic emission. A direct comparison between IPC and non-IPC mode is not straight forward as the turbine is operated during higher power production more frequently in IPC mode, than during lower power production. However, results show, that the effect of IPC on mechanical loads depend on each individual component of the turbine. Damage equivalent loads (DELs) are either increased or decreased by the use of IPC depending on the component. The acoustic measurements show that the sound pressure level (SPL) is increased in certain ranges of the rotational speed and decreased in others. For the electric power we find higher production during times, when the turbine is operated in IPC mode.