Robust Stability of Grid-Connected Voltage Source Converter With Phase-Locked Loop

The robust stability of one single voltage source converter (VSC) connected to a bus via the line is studied in this letter. Considering arbitrary bounded perturbations from uncertainties, the perturbed system model is firstly proposed. Then, one switched system is constructed to investigate the stability of the perturbed system, and it is proved that the stability region of the switched system is the subset of that of the perturbed system. Finally, the stability region of the switched system is obtained by the inverse-time (backwards) integration starting from the unstable equilibrium point, which is also the conservative stability region of the perturbed system.