The measurement method of power capacitor tanδ based on Kaiser-window

The dielectric loss factor (tanδ is an important parameter to assess the running state of power capacitor. Aiming at solving the question that spectrum leak and picket fence effect of traditional harmonic analysis method which are caused by asynchronous sampling and non-integer-period truncation, the modified harmonic analysis method based on Kaiser-window function phase correction is put forward in this paper to measure the dielectric loss factor of power capacitor, according to the Kaiser window function´s characteristic that attenuation proportion can be chosen freely, which is between main lobe and side lobe. Under three conditions of the grid frequency fluctuation, the change on the true value of tanδ, and the white noise interference, the measurement errors of this algorithm and the other interpolation algorithms which are based on Hanning Window and Blackman Window are emulated and analyzed. The results show that this method can overcome the impacts of grid frequency fluctuation and white noise more effectively, compared with Hanning and Blackman windows interpolation algorithms, the effect of the modified harmonic analysis method based on Kaiser window is good on restraining frequency spectrum leakage, and the accuracy of this method is high, so that it can meet the requirements of on-line detection of tanδ in power capacitor.