| Title |
Overcurrent-Limiting Control Method for Grid-Forming Inverters Based on Seamless Transition to GFL Mode |
| Authors |
Hojun Lee ; Hyunjun Kim ; Myeonghwan Min ; Eun-Soo Lee |
| DOI |
https://doi.org/10.6113/TKPE.2026.31.3.230 |
| ISSN |
1229-2214(pISSN), 2288-6281(eISSN) |
| Keywords |
Overcurrent limit control; Grid-connected inverter; GFM (Grid-Forming) inverter; GFL (Grid-Following) inverter; Re-entry strategy |
| Abstract |
This paper proposes a seamless transition-based overcurrent limiting control strategy for GFM(Grid-Forming) inverters to ensure stable operation during grid fault conditions. Under voltage sags, GFM inverters are inherently exposed to severe overcurrent, while conventional limiting methods may result in output distortion, phase discontinuity, and controller windup. To address output distortion, phase discontinuity, and controller windup, the proposed method uses a seamless transition from GFM to GFL mode under overcurrent conditions. Preloading the internal phase and current controller states at the transition instant ensures that phase continuity and current reference continuity are preserved, effectively suppressing transient overcurrent and eliminating control discontinuities. The dynamic performance of the proposed method is analyzed through PSCAD/EMTDC simulations. Experimental results obtained from a 20-kW three-level T-type inverter validate the effectiveness and practical feasibility of the proposed control strategy. |