Stability Analysis and Capacity Distribution of Multi-paralleled Current-Controlled Inverters and Voltage-Controlled VSGs Grid-Connected System

The large-scale access of current-controlled inverters (CCIs) has caused weak grids and a series of instability issues. On the contrary, because of can actively support the weak grid, voltage-controlled VSGs (VC-VSGs) have become a potential choice for high-penetration renewable energy power generation. Multi-paralleled CCI and VC-VSG grid-connected systems (MCVGSs) are account for an increasing proportion of the distributed generation systems. This paper focused on the influence of short-circuit capacity ratio (SCR) and VC-VSG capacity ratio (VSGCR) on the MCVGS small-signal stability. Then, this paper proposes an SCR-based VC-VSG capacity distribution method, which can determine the VC-VSG capacity required to maintain a certain MCVGS stability margin in a weak grid. Finally, simulation results validate the analysis and the proposed method.