Pre-Synchronization Method of Virtual Synchronous Generator Applied to Microgrid

Virtual Synchronous Generator (VSG) can effectively mitigate the inertia drop caused by grid connection of renewable energy, but VSG is prone to generate transient current at the moment of grid connection, resulting in switchover failure. This paper presents a pre-synchronization method for VSG off-grid switching. First, the control principle of VSG is analyzed. Secondly, an improved PLL-free pre-synchronization control strategy is proposed, which eliminates the PLL and simplifies the control structure. Finally, the correctness of the proposed strategy is verified by the simulation results.