Implementation of the frequency-partitioning fitting method for linear equivalent identification from frequency response data

It is often the case that the frequency response data of a network or a system is available and one wants to identify a linear equivalent from the frequency response data for time-domain simulations and other purposes. To this end, a variety of methods have been proposed, and the vector fitting (VF) method and the frequency-partitioning fitting (FpF) method are often used for electromagnetic transient (EMT) simulations of power systems. The main applications are frequency-dependent transmission-line modeling and frequency-dependent network modeling. This paper presents illustrative MATLAB code of the FpF method. Although the mathematical descriptions of the algorithms used in the FpF method have been fully presented in the literature, the illustrative code is still useful and necessary to understand the details of their implementation. It is verified that the code shown in this paper is fully functional and it can be used as a functioning software package.