Design and parameter analysis of an improved pre-synchronization method for multiple inverters based on virtual synchronization generator control in microgrid

The microgrid is increasingly important because of the rapid development of renewable energy. Meanwhile, power converter is an important interface, where the stable operation of microgrid need effective inverter control strategy. The virtual synchronous generator technology emulates the synchronous generator's electromechanical transient characteristics, which has been used in the inverter of microgrid in both the grid-connected and islanded mode. While switching from islanded mode to grid-connected mode, the virtual synchronous generator based microgrid need a pre-synchronization method to avoid voltage distortion and current surge. The previous pre-synchronization methods usually focus on the synchronization of single inverter, which may lead to the dynamic power distribution problem in mode switch. This paper presents an improved pre-synchronization method for virtual synchronous generator based multi-inverter microgrids, which can realize the seamless switching and rational power distribution. In addition, to optimize the performance in mode switch, the influence of pre-synchronization parameters on the pre-synchronization microgrid is analyzed, which provides useful advice to the parameter design. Finally, the experimental platform of microgrid based on dSPACE is built to verify the effectiveness of the proposed control strategy.