Simulation investigation of wind turbine imbalance faults

This paper investigates the use of simulations to study wind turbine imbalance faults. The dynamics of a model wind turbine generator (WTG) are simulated in a combined environment of TurbSim, FAST (Fatigue, Aerodynamics, Structures, Turbulence), and Simulink in three different scenarios, i.e., normal operating conditions, blade imbalance, and aerodynamic asymmetry. The blade imbalance is simulated by scaling the mass density of one blade, which creates an uneven distribution of mass with respect to the rotor. The aerodynamic asymmetry is simulated by adjusting the pitch of one blade, which creates an uneven torque across the rotor. The time-domain simulation results of the WTG output electric power are transformed into the frequency domain using the Fast Fourier Transform (FFT). A power spectrum density (PSD)-based method is then developed 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 output electric power with the characteristic frequencies the same as the rotating frequencies of the wind turbine. This work provides preliminary results that are useful for online detection of imbalance faults for wind turbines.