Dynamic analysis of monopile supported offshore wind turbines

K. A. Abhinav, Nilanjan Saha

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)
10 Downloads (Pure)

Abstract

This paper describes the stochastic dynamic response of National Renewable Energy Laboratory 5 MW offshore fixedbased wind turbine (OWT) under various soil conditions – medium dense sand, stiff clay and layered profiles in 20 m depth of water. The aerodynamic and hydrodynamic OWT loads are derived using the force-controlled approach. Usually the OWT generates power in an operational regime and survives at extreme wind speeds. Therefore, two met-ocean conditions adhering to the irregular Joint North Sea Wave Project spectrum are considered – one in an operational regime (average wind speed Vw = 12 m/s, significant wave height Hs = 4 m and peak spectral period Tp= 10 s) and another in a near cut-out regime (Vw = 22 m/s, Hs = 10 m, Tp = 14 s). The soil is modelled by way of a non-linear ground-to-spring model. For each sea state, time domain stochastic responses are calculated and the ensemble average response is calculated from 50 Monte-Carlo simulations. The change in ensemble average response due to changes in pile penetration depth and diameter of the piles for the three soil configurations is described. Results indicate that the dynamic response mainly depends on the stiffness of the soil and reiterate the need for detailed site-specific geotechnical investigations before designing OWT foundations.
Original languageEnglish
Pages (from-to)428-444
Number of pages17
JournalProceedings of the Institution of Civil Engineers: Geotechnical Engineering
Volume170
Issue number5
Early online date6 Sep 2017
DOIs
Publication statusPublished - 31 Oct 2017

Keywords

  • energy
  • offshore engineering
  • wind turbines

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