Comparison analysis on selectivity of resonant controllers for parallel active power filters

To reduce the computation burden, the current reference of the parallel active power filter could be obtained by subtracting the fundamental component from distorted load currents. However, this kind of mixed reference contains kinds of harmonic components. In this condition, the demand of selectivity should be fulfilled by the current controller, if the function of selective harmonic compensation is still required. In this paper, with regarding that the selectivity is a significant property, the proportional resonant controller and the vector resonant controller were compared. The comparison analysis includes their derivation, performances in the current control loop, and the influence to the system stability. Through the analysis, the features of each resonant controller were concluded: the proportional resonant controller shows poorer selectivity than vector resonant controller, and it should be used in conditions whose reference is accurately generated, while vector resonant controller has good selectivity and is more suitable for the aforementioned selective active power filter with mixed reference. Finally, all conclusions in this paper were validated through a 10 kVA laboratory prototype.