Simulation studies on imbalance faults of wind turbines

This paper presents the use of simulations to study imbalance faults of wind turbines. The dynamics of a model wind turbine are simulated in three different scenarios, i.e., normal operating conditions, blade imbalance, and aerodynamic asymmetry, using TurbSim and FAST. Blade imbalance is simulated by scaling the mass density of one blade which created an uneven distribution of mass with respect to the rotor. Aerodynamic asymmetry is simulated by adjusting the pitch of one blade which creates uneven torque across the rotor. The time-domain simulation results of the overall shaft torque of the wind turbine are transformed into the frequency domain using a Fast Fourier Transform (FFT). Power spectrum density (PSD) plots are then constructed to compare two imbalance fault scenarios with the normal operating conditions in the frequency domain. Results clearly show that both the blade imbalance and the aerodynamic asymmetry generate an excitation in the shaft torque at 1P, i.e., the rotating frequency of the wind turbine. This work provides preliminary results that are useful for detection of imbalance faults of wind turbines.