Large-Signal Stability of Grid-Forming Inverters via Adaptive Fault Ride-Through Enhanced Droop Control

Grid-forming inverters (GFIs) play a vital role in renewable energy integration, particularly in weak or islanded grids where voltage and frequency must be maintained without external support. This paper proposes an adaptive droop control strategy with integrated dynamic fault ride-through (FRT) logic for GFIs using LCL filters. Unlike conventional droop methods, the approach introduces feedback correction terms into frequency and voltage droop equations, allowing self-regulation under transients such as faults and sudden load changes. Reference values are dynamically adjusted based on system deviations, improving transient stability and fault resilience. The control framework incorporates cascaded inner voltage and current loops to ensure accurate tracking and fast dynamic response. Performance is validated in a five-inverter parallel system connected to a weak grid with a 30 kVA short-circuit level and an X/R ratio of 1, under severe conditions including three-phase faults, generation loss, and islanding. Simulation results confirm that voltage remains within ±5%, frequency within [49.99–50.01 Hz], and Rate of Change of Frequency (RoCoF) below 0.05 Hz/s, demonstrating robustness and compliance with IEEE 1547 and IEC 61727 standards.