A Multi-Function AAA Algorithm Applied to Frequency Dependent Line Modeling

Lucas Monzón, William Johns, Spatika Iyengar, Matthew Reynolds, Jonathan Maack, Kumaraguru Prabakar

Research output: Contribution to conferencePaperpeer-review

3 Scopus Citations


Modeling of power distribution system components that are valid for a wide range of frequencies are crucial for highly accurate modeling of electromagnetic transient (EMT) events. This has recently become of interest due to the improvements needed for the resilient operation of distribution systems. Vector fitting (VF) is a very popular and commonly used algorithm for wide band representations of power system components in EMT simulations. In this research, we present a new multi-input rational approximation algorithm (MIAAA) and illustrate its advantages with respect to VF using examples of approximations of admittance matrices discussed in the literature. We show that MIAAA not only outperforms VF in terms of achieving better accuracy using lesser number of poles, but also has no numerical issues achieving convergence. In contrast to VF, MIAAA is not sensitive to the location of input sample points and it does not require good estimates for the location of the desired approximation poles. The novelty of this research work is the use of recent mathematical results to solve existing challenges in distribution system modeling and to develop rational approximations for power system models that intend to be optimal in terms of accuracy and performance.

Original languageAmerican English
Number of pages5
StatePublished - 2 Aug 2020
Event2020 IEEE Power and Energy Society General Meeting, PESGM 2020 - Montreal, Canada
Duration: 2 Aug 20206 Aug 2020


Conference2020 IEEE Power and Energy Society General Meeting, PESGM 2020

Bibliographical note

See NREL/CP-5D00-75381 for preprint

NREL Publication Number

  • NREL/CP-5D00-79033


  • AAA algorithm
  • Barycentric formula
  • Computational modeling
  • Function approximation
  • Power system modeling
  • Rational approximations
  • Vector fitting


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