Abstract:Aiming at the problems of current shock, voltage distortion and power shock during microgrid connection, a switching control strategy of virtual synchronous generator (VSG) without phase-locked loop (PLL) is proposed. The control model of VSG is established. In the switching process, a pre-synchronization control unit without PLL is designed. The influence of PLL on system control precision and response speed is avoided. In addition, the control algorithm is simplified, the time of pre-synchronization is shortened, and the process of switching is accelerated. At the same time, to avoid the influence of the jump of Δθ during the control process, the angular frequency difference is directly fed back to the power loop. The integral anti-saturation link is also introduced to accelerate the adjustment and recovery process. Finally, the feasibility of the proposed control strategy is verified by simulation.