Transient Stability Analysis of Parallel Grid-Following and Grid-Forming Inverters With the Current Limiting Mode

With the integration of renewable energy into power grids, hybrid parallel systems comprising both grid-following and grid-forming (GFM) inverters have become increasingly common. However, the transient stability and control strategies of such systems under current limiting mode remain unclear. To address this issue, this article investigates the transient stability of both types of inverters operating under current limiting conditions during faults. First, a new modeling and analysis method is proposed and used to delineate the angle stability region. Second, the instability mechanisms of the two inverters are analyzed under different grid voltage sags and system parameters. Furthermore, the impact of the current control angles of both inverters on system stability is examined, leading to the proposal of a transient current limiting strategy that balances system transient stability with the desaturation capability of the GFM inverter. Finally, the effectiveness of the proposed control strategy is validated through comparative simulations and experiments against existing current limiting methods.