A comprehensive comparison of Virtual Synchronous Generators with focus on virtual inertia and frequency regulation

The concept of Virtual Synchronous Generator (VSG) may be used to make grid-connected power electronic converters behave as synchronous generators. VSGs can provide the ancillary services requested by the latest grid codes in a straightforward way, compatible with the already existing structure of power systems and with the advantage of being a digital model with tunable parameters (e.g., inertia constant). This represents a promising solution to mitigate the future reduction of the total power system inertia and the grid stability issues related to both the decommissioning of synchronous generation and the widespread penetration of electronically interfaced renewable power generators (especially solar and wind). Since the literature is rich of VSG models, it is important to have a clear overview of them. Therefore, this paper aims at performing a review and comparison of the active power control and inertial capabilities of ten VSG solutions available in the literature. First, each model is briefly described and a common tuning procedure is proposed to obtain a fair performance comparison. Then, experimental tests are presented to show the behavior of the VSGs.