Secondary Voltage Control for Harmonics Suppression in Islanded Microgrids

This paper proposes a secondary voltage waveform control approach to suppress harmonics in islanded microgrids. Compared with the secondary control for traditional large power systems, the proposed control scheme can regulate the voltage waveform instead of voltage magnitude of sensitive buses in islanded microgrids. In addition to the centralized controller for fundamental frequency voltage component, a selective harmonic compensator is implemented in the secondary voltage control system. With the help of Park transformation, the cyclic references generated by the selective harmonic compensator passed through a low-bandwidth communication system to each primary control system for distributed generation units. Thus, combined with the high-bandwidth local voltage controllers in the primary control systems, harmonic voltage distortions in islanded microgrids are redistributed and reduced. Simulations are performed to validate the effectiveness of the proposed control approach.