Three-phase harmonic compensation using the sliding DFT algorithm

This paper describes the sliding discrete Fourier transform (DFT) algorithm as an alternative for typical DFT used for spectrum analysis and synthesis. As an example a control circuit for three-phase 75 kVA parallel active power filter (APF) is used. Such filters have been built and tested. Some illustrative, experimental results are also presented in the paper. The control algorithms of the proposed APF are implemented in the floating-point digital signal processor ADSP-21061. The presented control APF algorithm is a good alternative to classical APF control algorithms, because it allows easy selection of control parameters in mains currents: imbalance, reactive power or harmonics contents.