Representation of multiport rational models in the ATP — Lumped network results

The use of dynamic equivalents is of fundamental importance to carry out electromagnetic transient studies in large-scale power systems, regarding high precision and acceptable computation time. There are several approaches for building these equivalents, being the most utilized the one based on rational models of transfer functions. Currently, due to its efficiency and robustness, the Vector Fitting has been the most used method to obtain these rational models. Thereby, the problem turns out to be how to include these rational functions of the complex frequency s in an electromagnetic transient program, particularly, in the ATP. Therefore, this paper proposes a method to represent multiport rational models (rational models of MIMO — multi-input multi-output transfer functions) in the ATP. The proposed method is a generalization of the method presented in [1], for interfacing rational models of SISO — single-input single-output transfer functions with the ATP.