A harmonic current suppression strategy for voltage source grid-connected inverters based on output voltage hybrid control in islanded microgrids

The principle of injected fundamental and harmonic current of grid-connected inverter with droop controller is analyzed firstly in this paper, and a compound harmonic current suppression strategy of GC-VCI with distorted grid voltage is proposed. A notch filter is firstly designed for the separation of different frequency components of the PCC voltage. Then the fundamental component of the inverter's output is controlled by the droop controller solely. A PIR complex controller is adopted for enhancing the tracking ability for harmonic component. As a result, the difference of harmonic voltage between PCC and the output point of inverter is reduced, and the injected harmonic current is decreased. These theoretical findings are verified through simulations and experiments on the laboratory platform.