Stability enhancement and parameter optimization of grid-forming converter control strategy considering overcurrent protection

• A transient stability enhancement strategy using negative asymmetric virtual impedance is proposed to raise power‑angle curve and increase power transfer margin. • An improved overcurrent protection strategy based on virtual power‑angle limiting is introduced, requiring no additional fault detection and working under both frequency and voltage transients. • The effectiveness and superiority of the proposed control strategies and parameter optimization are verified through theoretical analysis and MATLAB/Simulink simulations. With the rapid development of renewable energy, the scale of traditional grid-following renewable energy installations continues to increase. Due to the lack of active support voltage sources like traditional synchronous generators, power grid stability issues are becoming increasingly prominent. Grid-forming converters are inherently voltage sources, capable of actively establishing voltage and frequency, providing inertia support for the system, which is beneficial for improving system stability. Developing grid-forming renewable energy with active support capabilities has become a primary solution. Therefore, starting from the perspective of enhancing the transient stability of grid-forming converters, this paper proposes a transient stability enhancement strategy based on negative asymmetric virtual impedance and a virtual power angle current limiting method considering overcurrent protection strategy. It reveals the transient stability characteristics of grid-forming converters and further verifies the effectiveness of the proposed method under large grid conditions, providing a reference for further research and application of grid-forming converters.