Fault Ride-through Control of Grid-Forming Converters under Different Fault States

Grid-forming (GFM) converters are one of the main components of the power electronic equipment with high permeability, and their fault-ride through (FRT) capability is an important basis to ensure the stable operation of highly electronic power system. Based on this, this paper proposes an FRT strategy for GFM converters, which not only considers the hardware constraints (i.e., current constraints) of the converters, but also can keep GFM converters running in the protected mode under symmetric and asymmetric faults. Firstly, the FRT of GFM converter is analyzed in detail. Then, an appropriate FRT model and control method are established. Finally, the effectiveness of the proposed method is verified by power-hardware-in-the-loop (PHIL) simulation and experiment. The results show that compared with GFL, the proposed control method can guarantee the instantaneous injection of reactive current when the GFM converter fails to prevent the overcurrent problem. Finally, the GFM converter can still operate fault-tolerantly under severe fault conditions.