Transient Stability Improvement of Virtual Synchronous Generators under Current Limitation: The Benefits of Virtual Power Feedback

The Virtual Synchronous Generator (VSG) concept is a well-known control solution to facilitate 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 large short-circuit current. However, to cope with the hardware limitation of power converters, a current limitation strategy must be included. This current constraint affects the VSG’s dynamic by limiting the output power, causing a substantial acceleration of the virtual rotor and possible loss of synchronism. The literature reports different solutions to address this issue for models using the measured actual active power as feedback in the mechanical emulation. Nevertheless, the available solutions modify the VSG by adding complex control algorithms, often requiring fault detection capability. Therefore, this paper proposes a different approach, analyzing the benefits of using the virtual power feedback instead of the measured one. This paradigm shift leads to a significant stability improvement, as it is proven theoretically and experimentally in this paper.