Individual Pitch Control for Wind Turbine Load Reduction Including Wake Modeling

This paper presents an investigation on improving individual pitch control (IPC) for wind turbine load reduction for Region 3 operation with the wake interaction included under the context of wind farm operation. The Larsen wake model is applied for composing the rotor wind profile for downstream turbines under wake interaction, and the simple Jensen model is also described for comparison. The switched controllers were then designed based on the composite wind profile. The wind profile of the turbine wake was generated by modifying the NREL's TurbSim codes. The state-space models of wind turbine were obtained via linearization of wind turbine model available in the NREL's FAST. In particular, in order to obtain more accurate state-space models for IPC design, equivalent circular wind profile was generated so as to better determine the local pitch reference. Based on such models, IPC controllers were designed following the disturbance accommodating control (DAC) and periodic control framework for load reduction when wake interaction was considered. The simulation results showed that the turbine loads can be further reduced using the switching control scheme based on wake modeling, as compared with the generic DAC without wake consideration.