Sensitivity Analysis of Modal Parameters of a Jacket Offshore Wind Turbine to Operational Conditions

Nasim Partovi-Mehr, Emmanuel Branlard, Mingming Song, Babak Moaveni, Eric Hines, Amy Robertson

Research output: Contribution to journalArticlepeer-review

4 Scopus Citations


Accurate estimation of offshore wind turbine (OWT) modal parameters has a prominent effect on the design loads, lifetime prediction, and dynamic response of the system. Modal parameters can vary during the operation of OWTs. This paper studies the variation and sensitivity analysis of an OWT’s modal parameters with respect to operational and environmental conditions. Three finite element models of a jacket-supported OWT at the Block Island Wind Farm are created within the OpenSees, SAP2000, and OpenFAST platforms and validated using experimental measurements. The OpenFAST model is used to simulate the modal parameters of the turbine under various wind speed, rotor speed, power, yaw angle, mean sea level, blade pitch angle, and soil spring values. The model-predicted modal parameters of the first fore–aft (FA) and side–side (SS) modes are compared to those identified from experimental measurements. Results from the simulations show that the first FA natural frequency and damping ratio mostly depend on the rotor speed and wind speed, respectively, while yaw angle and mean sea level do not have a visible effect. It is observed that there is about 8% stiffening in the first FA frequency and an aerodynamic damping of 7.5% during the operation of the OWT.

Original languageAmerican English
Article number1524
Number of pages24
JournalJournal of Marine Science and Engineering
Issue number8
StatePublished - 2023

Bibliographical note

Publisher Copyright:
© 2023 by the authors.

NREL Publication Number

  • NREL/JA-5000-86979


  • Block Island Wind Farm
  • Campbell diagram
  • continuous vibration monitoring
  • fixed-bottom offshore wind turbine
  • jacket substructure
  • modal identification
  • modal parameters
  • operational conditions
  • sensitivity analysis


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