An Adaptive Fault Ride-Through Scheme for Grid-Forming Inverters Under Asymmetrical Grid Faults

Three-phase four-wire grid-forming (GFM) inverters are promising to interface distributed energy resources into low-voltage networks. However, these prone overcurrent under grid faults. Physically increasing the inverter current capacity is not cost-effective cope with complicated fault conditions. In this article, an adaptive ride-through (FRT) scheme based on instantaneous saturators and virtual negative- zero-sequence resistances proposed. It features only limitation by modifying voltage references, but also seamless transition between normal The proposed FRT first analyzed from different aspects, including sequence resistances, short-circuit ratio, types, levels. then designed be ensure high quality at healthy phase. verified MATLAB/Simulink simulations asymmetrical A laboratory platform a grid-connected 3kW GFM further constructed demonstrate its effectiveness (a video of experimental results three faults attached).