Multi-Port Networks Modeling in Power System Using Vector Fitting Method to Analysis of Electromagnetic Transients

Modeling of frequency-dependent components of power system is often based on a terminal description by an admittance matrix in the frequency domain. One challenge in the extraction of state-space models from such data is to prevent possible error magnification when the model is to be applied in time-domain simulations. The error magnification is a consequence of inaccurate representation of small eigenvalues of the admittance matrix. In the case of multiterminal problems, the output response is sometimes strongly dependent on the distribution of the applied input on the terminals. Such behavior is often observed in the low-frequency range, due to large differences between short-circuit and open- circuit modal characteristics .Direct application of standard modeling techniques to such cases gives a model with inaccurate representation of the small modes. So this paper represents a novel method to model multi-port networks using vector fitting approach. In the suggested method, the modeling error is avoidable.