新能源电源通过逆变器实现并网，其并网系统的电压幅值、相位、频率等物理量在电磁、机电等多时间尺度均存在强交互耦合，准确把握并网逆变器的同步稳定主导行为特征是目前的热点问题。为此，提出了一种多次密度空间聚类（density-based spatial clustering of applications with noise，DBSCAN）算法来分析多逆变器并网系统同步稳定的物理表征。首先建立了跟网型和构网型逆变器并网模型，分析了其同步控制单元的同步特性；其次利用所提算法实现对并网逆变器与公共连接点的相位差、逆变器功角、系统频率等仿真数据的聚类和分类；最后通过仿真分析表明，逆变器并网系统同步稳定特征表现为功角逐步恢复原来运行状态和新稳态，此外，系统同步稳定与频率稳定具有一致性。区别在于跟网型同步控制单元成功锁相可以表征其系统的同步稳定，而构网型同步控制单元无法表征。

The new energy source is connected to the grid through the inverter, and the voltage amplitude, phase, frequency and other physical quantities of the grid-connected inverter system have strong interactive coupling in electromagnetic, electromechanical and other time scales. It is a hot issue to accurately grasp the dominant behavior characteristics of synchronous stability of grid-connected inverters. Therefore, a multiple density-based spatial clustering of applications with noise (DBSCAN) algorithm is proposed to analyze the physical characterization of the synchronous stability of grid-connected multi-inverter systems. Firstly, the grid-connected models of grid-following inverters and grid-forming inverters are established, and the synchronization characteristics of their synchronous control units are analyzed. Secondly, the proposed algorithm is used to cluster and classify simulation data of the phase difference between the grid-connected inverter and the common connection point, the inverter power angle, the system frequency and so on. Finally, the simulation analysis shows that the power angle of the grid-connected inverter system is gradually restored to the original operating state and the new steady state. In addition, the system synchronization stability is consistent with the frequency stability. The successful phase locking of the grid-following inverters synchronous control unit can characterize the synchronization stability of the system, while the grid-forming inverters synchronous control unit cannot.