The Simulink model calculates the elements impedance composing the AC network equivalent represented by two inductors and one resistor. This type of configuration (LLR) is often used in HVDC links studies where it is relevant to correctly represent the damping angle (phase angle) at fundamental and a low harmonic (corresponding to a possible resonance frequency). Other configurations may also be suitable. Information about the network impedance variation with frequency will be necessary to choose the best configuration.
The parameters defined in the subsystem mask are: The fundamental frequency (50 or 60 Hz), the network impedance at the fundamental frequency, the harmonic number N (2,3,4,or 5), the (positive) phase angle (deg) at the fundamental and Nth harmonic.
The model solves a set of three nonlinear equations. You can trace the impedance vs. frequency of the resulting circuit using the Powergui.