Improvement of the controller algorithms for active power filters operating under distorted and unbalanced grid voltages

The most common reference current detection methods for shunt active power filters are optimized and compared in this article, theoretically and through experimental tests. One used discrete Fourier transform (DFT), d-q axes theory, p-q Instantaneous Reactive Power (IRP) theory and Sinusoidal Signal Integrators (SSI). MATLAB/Simulink software is used because it provides specialized tools in order to design, implement and simulate these algorithms. Afterward they are implemented in a real-time setup using a digital signal processor (DSP) based solution with dSPACE controller board. For the performance comparison one used criteria like total harmonic distortion (THD) and unbalance of detected fundamental current, run time for the DSP, settling time, transient performance and overshoot. This study contributes to the existing comparisons in specialized literature by testing the algorithms under distorted and non-symmetrical PCC voltages and may be useful for hardware implementations.