Grid-Forming Controller With Enhanced Disturbance Rejection

Grid-forming (GFM) inverters, like synchronous generators (SGs), form voltage at their terminals and are crucial for enabling high renewable energy integration. Most GFM controllers mimic the power-synchronization characteristics of the SG rotor’s swing dynamics to synchronize with the system. However, GFM inverters differ significantly from SGs in both dynamics and control. This paper systematically explores these differences. The analysis reveals that the coupling between steady-state and transient performance in traditional GFM controllers, influenced by the active power-frequency droop gain, along with the absence of features like large stator inductance, damper windings, and power system stabilizers, may result in SGs having superior disturbance rejection in the small-signal domain. Building on these insights, a novel GFM control scheme, Angle Restoration Control (ARC), with improved disturbance rejection performance, is proposed. A comparative stability analysis is performed to evaluate the robustness of the proposed scheme against conventional droop GFM controls under various grid conditions. Finally, the effectiveness of the proposed control method is further validated through simulations and real-time hardware-in-the-loop testing in diverse power system scenarios.