D-VI strategy for enhancing the low-voltage ride-through capability of virtual synchronous generators

Virtual synchronous generator (VSG) control, as a grid-connected inverter control strategy, provides inertia and damping characteristics to the power grid by incorporating rotational inertia and damping coefficients similar to those of synchronous machines. This is crucial for maintaining the safe and stable operation of renewable energy grid-connected systems. However, traditional VSG control exhibits weak low-voltage ride-through (LVRT) capability during voltage sags caused by grid faults, leading to increased output current and threatening grid operational safety. To enhance low-voltage ride-through capability, this paper proposes D-VI control based on analysing VSG fundamentals and fault characteristics. This approach incorporates dynamic power compensation, improved reactive voltage commands, and virtual impedance, effectively reducing both transient and steady-state values of VSG output current. Compared to strategies like direct power angle compensation, the proposed control significantly reduces computational complexity by directly extracting fault voltage for dynamic power compensation, enabling rapid response. Simulation results in MATLAB/Simulink validate the effectiveness of the proposed method in enabling VSG low-voltage ride-through capability.