A Frequency Domain Method for Instantaneous Determination of Reference Current in Shunt Active Filter

This paper presents a novel method in frequency domain to determine the reference current of a shunt active power filter. In this method the enormous amount of calculations to be carried out in discrete Fourier transform (DFT) is reduced to those required only for determination of the fundamental component. Moreover, a small section of the calculations is repeated, following each data sampling, to compute the new instantaneous value of the reference current. Output current of the filter is controlled by the hysteresis method. Using the proposed method, the main problem of the frequency domain methods, i.e., time delay for sampling and calculating, is solved. Steady state and dynamic performance of the proposed filter with non-ideal voltage source and converter are studied by computer simulations. The simulation results show the effectiveness of the proposed method