Grid conductance and susceptance estimation for power control in grid-tied inverters

摘要

A method for operating a voltage source inverter (VSI) connected to a power grid having a grid voltage. The method comprises controlling a magnitude of a VSI voltage and a phase between the VSI voltage and the grid voltage, determining active and reactive powers exchanged between the VSI and the grid, estimating one or more values indicative of the ratio of a grid conductance and of a grid susceptance based on the active and reactive powers. The method further comprises determining an active power deviation between the determined active power and an active power setpoint as well as a reactive power deviation between the determined reactive power and a reactive power setpoint, mapping the active and reactive power deviations to a phase deviation and to a magnitude deviation, the mapping being dependent on the estimated one or more values indicative of the ratio of the grid conductance and the grid susceptance, and correcting the magnitude of the VSI voltage and the phase between the VSI voltage and the grid voltage, based on the phase and magnitude deviations. (Fig. 2)