针对微电网并网时的电流冲击、电压畸变、功率振荡的问题，提出了一种基于无锁相环(PLL)的虚拟同步发电机（VSG）离并网切换控制策略。建立了VSG的控制模型。然后，在离并网切换的过程中，设计了一种无PLL的预同步控制单元，省去了PLL环节，避免了PLL对系统控制精度以及响应速度的影响，简化了控制算法，缩短了预同步的时间，加速了离并网切换过程。同时直接将角频率差值反馈回功率环，避免了Δθ符号跳变对控制过程产生的影响，并引入了积分抗饱和环节以加速调节恢复过程。最后进行了仿真验证，验证了该控制策略的可行性。

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.

国家重点研发计划项目(2016YFC0305001)