| CPC F03D 17/00 (2016.05) [F03D 80/50 (2016.05)] | 12 Claims |

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1. A method for monitoring at least one rotor blade of a wind turbine, the method comprising:
implementing, via a controller, a control scheme for monitoring blade damage of the at least one rotor blade, the control scheme comprising:
monitoring pitch motor current of a pitch system of the wind turbine;
converting the pitch motor current of the pitch system into a frequency domain;
monitoring one or more blade natural frequency-related components in the frequency domain of the pitch motor current for a local peak, the one or more blade natural frequency-related components comprising an armature current for a DC motor and a torque-related current component for an AC motor;
determining a natural frequency deviation by determining a difference between the local peak and a given natural frequency of the rotor blade, wherein a natural frequency deviation outside of a predetermined frequency range is indicative of a rotor blade anomaly; and
implementing a control action when the natural frequency deviation is outside of the predetermined frequency range.
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