A Filtering Perspective to SAPF Control for Current Harmonic Mitigation

Shunt active power filters (SAPF) are a tool for suppressing the harmonic content present in the electrical grid, caused by nonlinear loads. An important part of this system is the SAPF control, where the filter is controlled in order to supply the harmonic currents required by the loads. In this paper, we show that this control system, usually performed by pre-estabilished controllers tuned in the relevant frequencies, works as a measurement of the harmonic content in the electric power system (EPS) by means of band-pass filtering, in order to reinject it in the right amount. This new perspective indicates that the choice of quality factor of the band-pass filter may impact the result of the harmonic compensation in several ways, and can thus be used as a parameter for control design, as shown by simulation results.