Flexible control of grid-connected renewable energy systems inverters under unbalanced grid faults

Abstract

The sustainable energy opportunity of the future lies in the renewable energy-based distributed Power Generation systems (DPGSs). However, there are different concerns and integration issues that surround them. To increase the rate at which renewable energy can be used, this paper focuses on an integrated utility grid system. A novel strategy to control the grid side inverter is developed for a DPGS when considering an unbalanced grid. First, an analysis of the consequences of the occurrence of a fault on the grid is performed. Secondly, a control strategy is proposed to ensure the operation of the DPGS connected to the grid even if the latter is unbalanced. The proposed approach consists in developing control loops for each of the three symmetrical sequences in a specific reference frame to ensure the operation of the grid-connected DPGS even during asymmetrical grid voltage fault. The found results are promising in terms of the guarantee of service continuity during faulty conditions.