Similar to synchronous generators (SGs), the phenomenon of low-frequency oscillation (LFO) may occur when virtual synchronous generator (VSG) is involved in power grid, thereby negatively affecting the stability of the power system. In this paper, the oscillation mechanism of the power system composed of a VSG and infinite grid (single-VSG infinite-bus system) is analyzed, the conditions for the occurrence of LFO are unveiled, and a simplified damping selection method to suppress the LFO is provided, considering the adjustable damping of VSG. First, a small-signal model of the single-VSG infinite-bus system is established. The order of this system model is reduced using the damping torque analysis. Then, the mechanism of LFO under various dampings is analyzed. On this basis, a reasonable selection method of damping is drawn. The range of damping, where LFO converges, can be determined and the appropriate damping coefficient can be selected using this method. Finally, the effectiveness of the proposed method is verified by simulations and experiments.

与同步发电机（SG）类似，虚拟同步发电机（VSG）接入电网时可能会出现低频振荡（LFO）现象，从而对电力系统的稳定性产生负面影响。本文分析了由VSG和无限电网（单VSG无限母线系统）组成的电力系统的振荡机理，揭示了LFO发生的条件，并提出了一种抑制LFO的简化阻尼选择方法提供，考虑到 VSG 的可调阻尼。首先，建立了单VSG无限总线系统的小信号模型。该系统模型的阶数使用阻尼扭矩分析进行了降低。然后，分析了不同阻尼下LFO的机理。在此基础上，得出了合理的阻尼选择方法。阻尼范围，可以确定 LFO 收敛的位置，并可以使用此方法选择适当的阻尼系数。最后，通过仿真和实验验证了所提出方法的有效性。