Analysis and simulation of small signal stability of parallel connection of virtual synchronous generators in a microgrid system

The penetration of renewable energy sources into electrical networks using power electronic converters, due to their low inertia, causes electrical networks to respond negatively to load changes and the periodic nature of generation, which leads to increased frequency fluctuations and reduced power system stability. Synchronization of the inverter with the main grid is of great importance in inverter-based units, so that even in times of disruption or changes this synchronization with the grid must be maintained. Virtual synchronous generator (VSG) technology is used to simulate the characteristics of a synchronous generator to create damping and virtual inertia in a renewable energy-based power system in order to reduce frequency fluctuations and improve stability. Small-signal stability analysis using a small-signal model of parallel connection of two virtual synchronous generators is presented in this paper. For modeling, the second-order model of the virtual synchronous generator was used. The results of the dynamic behavior simulation are reviewed and analyzed by calculating the modes of the system matrix. Also, the participation coefficients are calculated to show the relationship between the system modes and state variables.