Improving Post-Fault Transient Stability of GFM Inverters Using Fault Current Injection

The current limiters play an important role in converter control to guarantee that the power electronics converter safely operates during fault conditions, especially in grid-forming converters where they operate as a voltage source. Among several types of current limiter techniques, the current saturation algorithm (CSA) is commonly used in the grid-forming inverter (GFM) and is known to cause poor post-fault transient stability. This study develops a fault current injection (FCI) for GFM to improve the post-fault transient stability of synchronverter-based GFM. The FCI methods are developed and validated via electromagnetic transient (EMT) simulations. The results have shown that the proposed method has improved the active and reactive power recovery in the post-fault period and also enhanced the post-fault transient stability by reducing the voltage angle deviation.