Enhancing Robustness and Interoperability of Grid-Forming Inverters via State Feedback Control

This paper evaluates, through simulations, the performance and robustness of grid-forming (GFM) inverter-based resources (IBRs) using state feedback and conventional proportional-integral (PI) controllers, both in the dq reference frame. The objective is to investigate whether a standardized control strategy among paralleled IBRs can improve system stability and contribute to the ongoing energy transition, where the penetration of renewable energy sources (RES) enabled by power electronics is steadily increasing. A linear quadratic regulator (LQR)-based state feedback control model is derived and implemented, and its performance under parallel operation is compared with the most commonly used control strategy for GFM inverters. The state feedback approach exhibits better performance under the studied conditions, demonstrating robustness under variations in grid parameters. Moreover, the IBRs show to be interoperable, capable of operating in parallel without interfering with each other. Notably, this stability is achieved without the need for auxiliary techniques such as virtual impedance.