Grid-Following Virtual Synchronous Machines: a valid solution fulfilling the newest grid codes regarding the reactive grid support during faults

The shift from conventional thermoelectric plants to renewable energy sources (RESs) will pose challenges in maintaining grid stability. Focusing on the Virtual Synchronous Machine (VSM) concept, this paper distinguishes between Grid-Following (GFL) VSMs and Grid-Forming (GFM) VSMs, showing their differences and limitations. As a first contribution, this paper clarifies the distinction between GFM and VSM and emphasizes that GFL VSMs can support the grid during faults similarly to GFM VSMs. Next, experimental tests on both GFM and GFL VSM typologies confirm their compliance with National Grid grid codes requirements, demonstrating the VSMs’ ability to provide reactive current during faults independently on the GFM or GFL operation. Moreover, the findings demonstrate the superior performance of VSMs compared to conventional grid-following controls. The paper results surpass the limitations imposed by the Great Britain grid codes, which mandate operation as a GFM to ensure rapid reactive support during faults.