Online calibration of accelerometers for monitoring of wind turbine blade movement

Measuring acceleration at the blade tips of wind turbines is a promising approach in structural health monitoring for tracking blade movement and consequently reducing blade loads. Online calibration of accelerometers is crucial in identifying any changes in sensor properties introduced during mounting or by sensor aging. Acceleration due to gravity during steady states of the sensor can be used as a reference level for calibration.In our approach, steady states during standstills of the turbine were identified and static offset and cross-axis sensitivity were calibrated for an exemplary accelerometer. A simulation of sensor orientations during steady states demonstrated that diversely distributed orientations result in smaller calibration errors.Algorithms were tested with real data of sensors mounted on wind turbine blades. Results showed that identification of steady states is challenging due to low frequency vibrations of the blade. Nevertheless, calibration significantly reduced the error in measurements, thereby increasing accuracy in monitoring applications. Finally, the benefit of calibration was demonstrated by means of two applications in wind turbine engineering.