Abstract

In 2019, DNV started a Joint Industry Project called "ACE -Alleviating Cyclone and Earthquake challenges for wind farms".

The project was completed in early 2021 and based on the project results, a Recommended Practice (RP) for seismic design of wind turbines and their support structures will be developed and expected to be published in the same year. Working title is DNV-RP-0585 "Seismic design for wind power plants". It will supplement existing standards for wind turbine design like DNVGL-ST-0126, DNVGL-ST-0437 and the IEC 61400 series. The main topics of the upcoming RP will be addressed in this paper. This will include geotechnical aspects like determination of the seismic loading, damping and liquefaction. Another focus area will be the seismic load calculation and the details of combining the earthquake impact with wind and wave loads acting on the wind turbine and the structure.

Here, different options of analysis, particularly time-domain simulations with integrated models or submodelling techniques using superelements will be presented as well as compared against more simplified approaches in the frequency domain using response spectrum methods.

Last not least, overall safety level and acceptance criteria will be addressed as well.

Introduction

In the past, most of the offshore wind farms have been installed in European countries. In contrast to offshore wind projects in European waters, it became clear that impact from earthquakes is expected to be one of the major design drivers for the wind turbines and their support structures in other areas of the world. This topic is of high importance in offshore markets in the Asian Pacific region like China, Taiwan, Japan, Korea as well as parts of the United States where offshore wind projects are currently developed. So far, seismic design for wind turbines is not described in large details in existing wind energy standards while local standards from the civil industry as well as international offshore oil & gas standards do not consider the particular demands of modern wind turbines.

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