Fault Ride Through Control of Grid-Forming Converter Based on Inverse Time-Gradient Current Limiting

With the continuous increase of the penetration rate of new energy in the power system, the importance of grid-forming converters is increasingly prominent. However, grid-forming converters have obvious overcurrent problems under large disturbance conditions, and their current tolerance ability is generally weak, so current limiting control is required. The traditional current limiting strategy uses a fixed virtual impedance value and cannot take into account both the equipment overload capacity and the transient voltage support requirements. For this reason, this paper proposes a fault ride-through control technology for grid-forming converters based on inverse time-gradient current limiting. This technology realizes fault ride-through by making full use of the equipment overload capacity through establishing an equipment overload capacity characterization model, analyzing the transient voltage and current characteristics, and setting up a power reference value gradient adjustment module. The simulation results demonstrate the effectiveness of the theoretical analysis.