Improving power measurement using FFT techniques on electrical machines fed by a photovoltaic system

Active power measurement of an inverter-fed induction motor in a photovoltaic water pumping system is considered. An improved digital method based on FFT (fast Fourier transform) techniques is used. Measurement results show the advantages of this method over currently available power measurement apparatus. This technique is applied at the intermediate AC stage for inverter output power measurement corresponding to the power consumed by the motor. Thus, both motor and power converter behavior can be analyzed from the resulting power estimation according to efficiency or the electromechanical criterion. It is shown that the digital techniques used for the power measurement make it possible to obtain reliable results