Grid-Connected Characteristics Analysis of GFL PCS and GFM PCS under Dynamics Perspective

With the increasing penetration of new energy power generation, the contradiction of power imbalance in the power system is increasingly intensifying, leading to new energy storage receiving increasing attention. Although there are grid following (GFL) control and gridforming (GFM) control of power conversion system (PCS), they essentially realize the regulation of power exchange dynamics by adjusting the internal voltage amplitude/frequency dynamics of PCS when feeling the power dynamics of the grid. To analyze the grid-connected characteristics in the perspective of system dynamic behavior, in this paper, the causal cycle regulation mechanism between power and internal voltage of the power system dynamic process is firstly clarified. Then, take the current control timescale for example, the dynamics models of GFL and GFM PCS are established under active/reactive current excitation and internal voltage amplitude/frequency response. Based on the unified model, the rotational motion dynamics mechanism of internal voltage vector is clarified, and the impact of different synchronization control strategies on grid-connected characteristics is analyzed and verified.