Hybrid Voltage and Current Control of Distributed Energy Resources for Harmonic Compensation of Single-Phase AC Loads in DC Microgrids

In DC microgrids, AC loads are supplied through inverters. Single-phase AC loads create oscillatory instantaneous power, which results in a harmonic current on the DC side with twice the fundamental component's frequency. The flow of these harmonic currents in DC lines leads to increased losses and reduced voltage quality. This paper addresses the compensation of the harmonic current generated by local single-phase AC loads in DERs within DC microgrids. To achieve this, a novel control method for DERs is proposed, which simultaneously regulates the DC component of their output voltage and the harmonic component of their output current. This hybrid voltage and current control method (HCM) combines two decoupled outer loops for DC voltage and harmonic current regulation, along with an inner current loop. The operation of the proposed control is discussed in detail, and its effectiveness is validated through simulation results.