Published: 27 July 2020 27 July 2020
Pitch Health Indicator for Static Pitch Misalignment of Rotor Blades
Rotor blades pitch above nominal wind speed to limit the loads on the turbine. Below nominal power, there is no pitch control. As much as possible power is extracted from wind by optimising rotor speed. However, a design angle of attack must be respected, supposing a correct reference pitch angle. Misalignment can result in aerodynamic imbalance with increased fatigue loading and potential reduced performance.
Pitch misalignment can be absolute (blade vs design position) or relative (blade vs another blade). The GL 2010 Guideline provides acceptable values for absolute and relative (0.6°) misalignment. Around 25% of turbines suffer from misalignment above 0.6°. Field campaigns can be time-consuming and the risk of targeting healthy blades is significant. Therefore, a Pitch Health Indicator (PHI) has been developed by scrutinising SCADA data. The PHI helps to prioritise the turbines to be investigated/corrected in a cost-efficient way in the field.
By Nicolas Quiévy, Julien Masson, Fiona Buckley, Olivier Van Oost, Stephane Bronckers, Belgium
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