Design and sensitivity analysis of grid-forming converter control based on a disturbance observer

A control method is proposed for grid-forming converters equipped with an LCL filter. Input-output feedback linearization is used for the design of the proposed control method, where active power and voltage magnitude are directly controlled. The proposed control method has a disturbance observer that provides integral action. Transparent current control is included for fault ride-through purposes. The proposed control method allows the closed-loop poles to be freely placed in a simple manner. Sensitivity is analyzed to study the impact of parameter errors on the proposed control method. The analysis results are experimentally verified with a 12.5-kVA converter, demonstrating the excellent dynamic performance of the proposed method for both strong and weak grids in the presence of grid inductance estimation error.