Dual pitch revisited: Overspeed avoidance by independent control of two blade sections

摘要

Fast, coherent changes of wind speed during normal operation typically challenge the wind turbine's control system and can lead to ultimate loads and overspeed trips. In this work we demonstrate that independently controlling the aerodynamic forces along the blades' span can significantly reduce the risk of overspeeds in such situations. Specifically, we take up the concept of "dual pitch" where the blade is split up in an inner and an outer part with two independent pitch systems. We demonstrate that pitching the outer part towards feather and the inner part in the opposite direction (active stall) enables significant overspeed reduction without thrust force amplification. Simulations with a model of the IWT-7.5-164 reference turbine show that reductions of the maximum rotor speed of more than 10% of rated speed are feasible.