Test Methodology for Validation of Multi-frequency Models of Renewable Energy Generators Using Small-Signal Perturbations

Behnam Nouri, Lukasz Kocewiak, Shahil Shah, Przemyslaw Koralewicz, Vahan Gevorgian, Poul Sorensen

Research output: Contribution to journalArticlepeer-review

6 Scopus Citations


Providing trustworthy and accurate multi-frequency (or harmonic) models for renewable energy generators (REG) is an ongoing challenge for harmonic studies. There have been effective attempts to propose and design a test device to validate the harmonic models, mainly based on shunt current perturbations. However, using additional devices for perturbations is costly for converter-based test sites. This paper provides the test specifications to extend the application of the grid emulators for voltage perturbations and appropriate harmonic model validation. Besides, the effects of the sequence couplings, initial emissions, and power set-points on the test results have been overlooked in the literature. Considering these effects, this paper proposes a generic test methodology to obtain more accurate models in the sequence domain. The experimental verification of the proposed methodology is demonstrated using a 7 MVA grid emulator for testing of a 2 MVA photo-voltaic converter and a 2 MVA Type 3 wind turbine. This way, the test challenges, specifications, and recommendations are presented using the MW-scale experiments on different REGs. Furthermore, the effects of sequence couplings and initial emissions on the calculation results are investigated and compared. The proposed methodology is applicable for harmonic model validation as well as empirical modelling.

Original languageAmerican English
Pages (from-to)3564-3576
Number of pages13
JournalIET Renewable Power Generation
Issue number15
StatePublished - Nov 2021

Bibliographical note

Publisher Copyright:
© 2021 The Authors. IET Renewable Power Generation published by John Wiley & Sons Ltd on behalf of The Institution of Engineering and Technology

NREL Publication Number

  • NREL/JA-5D00-80405


  • impedance measurement
  • multi-frequency models
  • stability
  • wind turbines


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