Study on VSG Control-based NPC-type Three-level Grid-forming Inverter
The large-scale integration of new energy generations will make the grid exhibit low inertia and underdamping,and hence vulnerable and unstable to impacts owing to the connection of a large proportion of inverter devices and the lack of inertia and damping of synchronous generators.Virtual synchronous generator (VSG)control can solve this problem. rad This work designed a VSG-based control strategy for NPC-type three-level grid-forming inverters which can signifi-cantly improve the quality of power output compared with the conventional two-level inverter VSG control.First a small signal model of VSG was established and the effects of moment of inertia J and damping coefficient D on the output active power characteristics and frequency were analyzed.Second the stability analysis was conducted by utilizing the active power closed-loop transfer function,the Bode plots,and root trajectories.Finally simulative verification was carried out via the MATLAB/Simulink,demonstrating the feasibility and effectiveness of the proposed control strategy.
virtual synchronous generatorNPC-type three-level inverternew energy generationmoment of inertia
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