Proportional Resonant (PR) controller for distribution power system. A proportional-resonant (PR) controller is used for replacing the conventional proportional-integral (PI) controller in this system. By comparison with the conventional PI control method, the PR control can introduce an infinite gain at the fundamental frequency and hence can achieve zero steady-state error. A theoretical analysis of the PR controller is presented and verified by experiment. Furthermore, a pseudo synchronous d-q transformation is employed in current control scheme and an all-pass filter based three-phase digital phase-locked loop (PLL) is introduced to detect the phase of grid voltage.