Transient response evaluation of stationary-frame resonant current controllers for grid-connected applications

This study deepens on the transient response analysis of the so-called vector proportional-integral (VPI) controllers and compares them with the popular proportional-resonant (PR) controllers for grid-connected applications. The employed methodology is based on the study of the error signal roots: both reference tracking and disturbance rejection abilities are considered for proper gain tuning. This study proves that PR controllers lead to shorter settling times than VPI controllers. A three-phase voltage source converter prototype has been implemented. Experimental results comparing the transient behaviour of VPI and PR controllers in different conditions are provided: a + 90° phase-angle jump in the current reference and a `type C´ voltage sag at the point of common coupling.