Control of grid-connected DC-AC converters in distributed generation: Experimental comparison of different schemes

In this paper, different control schemes for grid-connected DC-AC power converters are discussed and compared with experimental results. The voltage controller based on H∞ and repetitive control techniques is compared with a traditional proportional-integral (PI) controller implemented in synchronously rotating reference frame and a proportional resonant (PR) controller implemented in stationary reference frame, with main focus on harmonics distortion and DC current injection to the utility grid. The result shows that the H∞ repetitive controller offers significant improvement in waveform quality and current harmonic distortion over conventional PI and PR controllers.