Key Factors Affecting the Oscillation Stability of GFL and GFM Energy Storage Cluster Grid-connected Systems

Energy storage systems are being extensively integrated into the power grid in the Xinjiang region of China due to their bidirectional power characteristics and flexible adjustment capabilities, which effectively enhance the damping levels of the new energy grid. However, a key issue that has not been addressed in relevant studies is whether the large-scale grid connection of grid-following (GFL) and grid-forming (GFM) energy storage clusters will lead to new oscillation instability risks and what the key influencing factors on oscillation stability are. The article conducts equivalent modeling of GFL energy storage and GFM energy storage clusters, revealing the collective impact of energy storage clusters and specifying the influence of the number of units and transmission line length on the system's oscillation stability. The conclusion drawn is as follows: 1) Under weak grid conditions, the oscillation stability of GFL energy storage is affected by the number of units (N) and transmission line length (XL). As N and XL increase, the risk of instability also increases; 2) The small-disturbance stability of GFM energy storage is not influenced by factors. Finally, taking the energy storage cluster with 15 GFLs or 15 GFMs connected to the grid as an example, the theoretical analysis and conclusions of this paper were verified.