Analysis and Mitigation of Harmonic Resonances in Multi–Parallel Grid–Connected Inverters: A Review

Abstract

With the move towards decarbonization of the energy system and increased use of renewable generation, the number of power electronics converter interfaced resources connecting to the grid is growing. These power electronics converters have fast dynamics determined by control algorithms, which leads to significant changes in the dynamics and impedance characteristics of the power system. Based on practical experience, concerns have grown about interactions between converters and between converters and the grid which can give rise to instability in a system with multiple grid–connected inverters operating in parallel. This paper reviews the recent work related to the understanding, modeling and mitigation of such interactions. The basic concepts which underpin the interactions are explained and discussed from an impedance stability perspective. The concepts are illustrated by means of an example case of multiple inverters operating in a low voltage distribution system. In recent years, several approaches have been proposed to prevent or mitigate the effects of these interactions. The mitigation approaches proposed in the most recent works are categorized and comprehensively reviewed.

Keywords

• multi–paralleled <i>LCL</i> grid–connected inverters
• admittance model
• resonance analysis
• harmonic resonances mitigation