A Unified Voltage Harmonic Control Strategy for Coordinated Compensation With VCM and CCM Converters

Harmonics have been considered as one of the major issues in modern power grids. Considering the high penetration level of power electronic converter interfaced distributed generation (DG) units, it is of interest to provide ancillary services through DG interfacing converters, such as harmonic compensation. In that case, multiple DG interfacing converters are utilized to compensate harmonics, and the compensation effort should be properly shared among these converters. However, it is rarely considered in existing literatures that converters operating in different modes, such as voltage-controlled mode (VCM) and current-controlled mode (CCM), need to cooperatively provide the compensation function. Aiming at this objective, this paper proposes a unified voltage harmonic mitigation strategy for VCM and CCM converters with high harmonic current sharing accuracy. Another advantage of the proposal is that the grid-side and load-side current measurements are avoided, which reduces the implementation cost. Experimental results are presented to demonstrate the effectiveness of the method.