Techniques of active load´s current or/and power computing for dynamic compensation of three-phase symmetrical system

The paper deals with computing techniques of both active current and power, and their DSP implementation for dynamic compensation of three-phase symmetrical system. The dynamic power active filter using this techniques is determinated for the VAr and higher harmonics compensation of symmetrical nonharmonic/nonlinear loads. The new original concept, which has been used, is the creation of a complex vector of investigated quantities and its hardware decomposition into real- and imaginary components using Clarke orthogonal transform. The analysis can be completed within one sixth of the period for three-phase system (from acquired data of previous sixth), due to six-side symmetry of complex vector. The compensator response to the actual state of the load is then very fast. Discrete Fourier transform and/or numeric solution of active power computation are used for generating new reference data for each successive sixth of the period. The computation-mainly integration can be done by either fast digital signal processor or mixed (analog) signal unit. Simulation experiments in DesignLab environment are presented at the end of the paper