The Virtual Power Feedback: Enhancing the Transient Stability of Virtual Synchronous Generators Under Current Limitation

The Virtual Synchronous Generator (VSG) concept is a well-established control solution that facilitates the integration of power electronics-interfaced renewable sources into the electric grid. The VSG algorithm enables power converters to support the grid in case of voltage dips by injecting a large short-circuit current. However, a current limitation strategy must be implemented to address the hardware limitation of power converters. As demonstrated in the literature, the current constraint affects the VSG's dynamics by limiting the output power, thus causing a substantial acceleration of the virtual rotor and potentially leading to a loss of synchronism. Several available solutions utilize the measured actual active power as feedback, thereby modifying the VSG with complex control algorithms. On the other hand, this paper proposes a different approach, highlighting the benefits of using the virtual power instead of the measured power feedback for the most adopted limitation strategies available in the literature. This paradigm shift leads to a significant improvement in stability without requiring fault detection capability or switching the control structure, as demonstrated both theoretically and experimentally in this paper.