Small signal modeling and frequency oscillation analysis of multi-VSGs in microgrids

Abstract With the widespread integration of renewable energy into the power grid to reduce carbon emissions, the inertia of the power system is degraded, significantly weakening its anti-interference ability. Virtual synchronous generators provide inertial support to power systems by imitating the mechatronic characteristics of synchronous generators, which improve dynamic performance while leading to frequency oscillation after disturbances. A simplified small-signal model for multiple virtual synchronous generators in microgrids is developed using state-space equations, enabling direct assessment of microgrid stability via the system matrix eigenvalues. Then, the influence mechanism of virtual inertia, damping coefficient, active droop coefficient and line impedance parameter changes on system frequency stability is further discussed and the impact of introducing virtual inertia on active power and frequency oscillation characteristics is analyzed. Finally, the active power and frequency oscillation simulation is performed to validate the model and analysis on the MATLAB/Simulink platform. The proposed model and analysis results contribute to the stability reinforcement of microgrids and promote the utilization of distributed renewable energy generation.