Transient Stability Analysis of Grid-Forming Converter Based on DC Voltage Synchronization Control with Current Limiting Effects

In addressing the issue of angle stability in grid-forming converters under current limiting constraints, this paper establishes an angle-switching model for a single grid-forming converter connected system based on Direct Current Voltage Synchronization Control (DVSC) that considers current limiting. Unlike traditional grid-forming converters that operate in a single mode after fault clearance, grid-forming converters with current limiting constraints may operate in different control modes. Therefore, this study employs the Segmental Equal Area Criteria (SEAC) to investigate the transient stability of the proposed model and derives an analytical expression for the critical clearing angle (CCA) of the system. It reveals the mechanism of the impact of the saturation current angle on system stability. Additionally, this paper presents a method to enhance the transient stability margin of the system by setting the current saturation angle. This not only prevents the system from getting locked into the current limiting mode after fault clearance but also allows for achieving the maximum critical clearing angle and reduced deceleration area. Finally, the correctness of the critical clearing angle expression and current saturation angle setting method is verified through simulations using MATLAB/Simulink.