Harmonic power sharing and PCC voltage harmonics compensation in islanded microgrids by adopting virtual harmonic impedance method

摘要

This paper proposes a new control scheme for harmonic power sharing and PCC voltage harmonics compensation in islanded microgrids by adopting virtual harmonic impedance method. Firstly, a droop relationship between the equivalent harmonic impedance of distributed generation (DG) units and their remaining power capacities (ZDG_h_eq-SDG_remaining droop relationship) is put forward. Then, a virtual harmonic impedance method based on detecting the output harmonic current of DGs is introduced and it is combined with the ZDG_h_eq-SDG_remaining droop relationship to form a control scheme for DGs in islanded microgrids. With this control scheme, harmonic power is shared among DGs according to their remaining power capacities without communication systems and PCC voltage harmonics can be effectively compensated. A harmonic distortion limit module is added to the proposed control scheme so that the THD of PCC voltage can be kept less than 5% even under relatively severe load conditions. Finally, the effectiveness of the proposed control scheme is verified by simulation results.