Abstract: [Objectives] Virtual synchronous generators (VSG) are extensively utilized for their capability in regulating damping and inertia in the grid-connection of inverters. However, during the actual operation of the inverter, common impedance as well as voltage and current distortion occur during off-grid/grid-connected pre-synchronization. [Method] This paper uses photovoltaic power generation system and hybrid energy storage instead of traditional DC source to simulate the actual situation. Additionally, virtual active power and virtual current are incorporated into the conventional VSG model to compensate for phase difference and amplitude difference during the grid-connection process, thereby achieving frequency and voltage regulation. To solve the problem of proportional plus derivative control (PD) control parameters selection in traditional linear active disturbance rejection control system, fuzzy linear active disturbance rejection control is adaptive to adjust PD control parameters, and fuzzy linear active disturbance rejection control is introduced into active loop for secondary frequency modulation to increase the robustness of the system. [Results] The feasibility of this method was verified by Matlab/Simulink simulation, and the pre-synchronization control system could run perfectly. [Conclusions] Fuzzy active disturbance rejection control can quickly realize smooth grid-connection, restrain the current shock and reduce the frequency oscillation, so as to improve the stability of grid-connected inverter-grid interaction system.

Key words: virtual synchronous generator (VSG), distributed energy resource, pre-synchronization, impedance, fuzzy linear active disturbance rejection control