Pitch control for wind turbine load mitigation and enhanced wake mixing

Abstract

The dissertation discusses different wind turbine control strategies that use pitch actuation to decrease the Levelized Cost of Energy (LCoE) of wind farms. This is achieved by either mitigating the loads experienced by individual turbines, or by enhancing wake mixing in turbines located within a wind farm. The latter strategy exploits the fact that wake mixing results in a lower wake deficit, such that turbines located in a wake can generate more power. Wind tunnel experiments are conducted to provide the next step in the development of two control strategies: Subspace Predictive Repetitive Control (SPRC) for load mitigation, and Dynamic Induction Control (DIC) for enhanced wake mixing. These strategies are compared with state-of-the-art technologies to assess their viability as wind turbine control approach. Both technologies prove to be effective in this environment, and achieve results that are similar to or better than state-of-the-art technologies. Finally, this dissertation introduces a novel pitch control technology as an alternative to the DIC approach. This technology, called the Helix approach, uses Individual Pitch Control (IPC) to enhance wake mixing and increase wind farm power generation. A proof of concept of the Helix approach is given through high-fidelity flow simulations.