Structure and Parameters Estimation of Complex Grid Impedance

This paper presents a novel frequency-based method to estimate the structure and parameters of a grid equivalent model by measuring currents and voltages at the terminals of the point of common coupling. This model is instrumental in calibrating the controller of grid connected power converters. The proposed approach is demonstrated on the two most common equivalent grid structures of second and forth order respectively, and can be generalized to arbitrary grid order. Additionally, the method provides a measure to assess the quality of available data for estimation purposes, and therefore to determine the estimation feasibility with the given data-set.