Grid Impedance Identification Based on Active Power Variations and Grid Voltage Control

This paper presents a novel method for identification of grid impedance which can be applied to grid connected power converters. Active power variations together with grid voltage control are used to obtain two operating points necessary for the algorithm proposed. Grid currents and voltages in the two operating points are then reported to an arbitrary synchronous reference frame, resulting the equations for identification of inductive and resistive parts of grid impedance. Simulation and experimental results are used to validate the proposed algorithm in case of inductive and resistive grids. The accuracy of impedance identification is comparable to that of commercial products designed for grid impedance measurement.