A Full Comparison between Droop Control and Virtual Synchronous Generator Control Considering Reactive Power Dynamics in Grid-Forming Inverters

With the growing penetration ratio of renewable energy sources in the power grid, the grid-forming inverters arrest great attention owing to improved stability and frequency supporting ability. Usually, the droop control and the virtual synchronous generator control are two commonly utilized power distribution strategies among paralleled grid-forming inverters. This paper gives a full comparison between these two control strategies considering both active and reactive power dynamics. Meanwhile, the small-signal dynamics on both grid-connected operation and stand-alone operation are also compared. Moreover, the unity between these two control strategies is explored, considering the detailed implementation of virtual synchronous generator control. The implicit droop characteristics of virtual impedance are also derived. The theoretical results are verified by software simulations and hardware experiments.