Direct Control of the Inverter Impedance to Achieve Controllable Harmonic Sharing in the Islanded Microgrid

Harmonic current sharing is an important aspect of islanded microgrid due to the presence of nonlinear loads. The existing harmonic current sharing strategies suggest a tradeoff between voltage quality and harmonic sharing effectiveness. In this paper, a novel control strategy is proposed to achieve current harmonic sharing by directly controlling the inherent impedance of the inverter. The proposed technique achieves harmonic sharing, in a distributed generation (DG)-based islanded microgrid, without using any communication infrastructure. This paper also proposes a droop technique to distribute the harmonics generated by the nonlinear load as per the kVA ratings of different DG units in the system. The proposed concept of variable inverter impedance and its application in an islanded microgrid is validated using experimental studies.