Investigation of Imbalance Faults in Horizontal Axis WTGS through Analysis of Generator Current Signal

This paper presents imbalance faults investigation of wind turbine system through generator’s current signal. A simulation model of wind turbine generator is developed in MATLAB and FAST (Fatigue, Aerodynamics, Structure and Turbulence) to carry out simulations. Various imbalance faults are introduced in wind turbine’s mechanical system using FAST. Simulink is further used to feed turbine data in permanent magnet synchronous machine and capture current signal. It has been observed that any changes appearing in rotating frequency of wind turbine can be measured by utilization of appropriate sensors i.e. torque sensor. This observation has been taken to next stage by analyzing generator’s current signal at ground station for fault detection. This is because the mechanical link of turbine’s shaft to that of generator, associates variations appearing in fundamental shaft frequency of turbine with current or voltage output of generator. Using simple FFT, current signal is analyzed for imbalance fault excitations. Through all simulations it has been strongly observed that when aerodynamic asymmetry or blade imbalance fault is introduced in system, excitations in current signal of generator appear at turbine’s fundamental rotating frequency. Multiple scenarios like altering mass or pitch of one or multiple blades of three-bladed turbine are simulated. All of which have shown same pattern of excitations as stated earlier. This method of fault investigation does not need any additional sensors or climbing up of turbine. Moreover, current signal analysis results can be compared with previous normal results to seize any other abnormalities in WTGs behavior.