A Power Angle Limiting Method for Improving Stability of Grid-Forming Inverter Under Overcurrent Condition

For conventional grid-following inverters, the overcurrent protection can be fulfilled easily by using the current reference limiting method. However, when this method is used for grid-forming (GFM) inverters, it may jeopardize the stability, because the power synchronization control law is destroyed when the current limit is triggered. To address this problem, this paper proposes a power angle limiting method used for the virtual-admittance-based GFM inverters, which can properly limit the output power and current of the inverters. Since limiting the power angle is more reasonable than directly limiting the current, the stability can be improved by using the proposed method. Detailed implementation of the proposed method is illustrated in this paper. Besides, the effectiveness of the proposed method is verified by the time-domain simulation.