A Pre-synchronization Scheme for Grid Connection of Multiple Virtual Synchronous Generators Based on Current Limiting Link

For distributed renewable energy devices that can operate in both grid connected and island mode, and can switch between the two according to demand, The key issue in the switching process is the pre-synchronization of voltage amplitude, frequency and phase. In recent years, the emergence of decentralized microgrid structures which has relatively independent power sources rendered traditional pre-synchronization technology obsolete. An independent pre-synchronization scheme was proposed that completes parallel pre-synchronization functions of multiple machines without the need for intercommunication. Based on the MATLAB/Simulink platform, a power simulation model containing multiple distributed photovoltaic virtual synchronous machines was constructed, and a pre-synchronization control unit and control parameters were designed. The influence of pre-synchronization control parameters on the dynamic power circulation during the pre-synchronization process was analyzed, and control performance under different conditions were obtained, verifying the excellent performance of the proposed pre-synchronization grid connection strategy, and suggestions were proposed accordingly.