Experimental Benchmarking of Voltage Controllers for Grid-Forming Inverters

With the wide-scale adoption of renewable energy sources in power systems, leading to more inverter-based systems, grid-forming (GFM) control is of importance to the grid stability. For the GFM control, the inner control loop in a dual-loop control scheme is critical for impedance-reshaping and current-limiting. Nevertheless, the voltage controller (VC) is also a limiting factor that makes the GFM inverter prone to instability in the stiff grid. To ensure the stability of the GFM inverter, robust and reliable VCs are in demand. Therefore, in this paper, a unified power transfer model is proposed to evaluate the influence of the VCs. Meanwhile, the main VCs are experimentally benchmarked in terms of dynamics. Different grid conditions are considered to explore the performance of the VCs.