How do wind turbines respond to winds, ground motion during earthquakes?
Wind simultaneously exerts dynamic loading, damping effect on seismic
response of wind turbines.

Date:
August 24, 2021
Source:
American Institute of Physics
Summary:
Wind power has experienced fast growth within China during the
past decade, but many wind farms are being built within regions of
high seismic activity. Researchers are now exploring the dynamic
behaviors of wind turbines subjected to combined wind-earthquake
loading. The group discovered that changes in the wind increase
and decrease the response amplitude of the wind turbine under weak
and strong earthquakes, respectively.



FULL STORY ==========================================================================
As China's economic development continues, energy demand is rising
along with it. Meeting this energy demand via fossil fuels is becoming increasingly undesirable, because it poses environmental and climate
risks.


==========================================================================
One solution is to embrace renewable energy sources, such as wind
power, and it has experienced fast growth within China during the past
decade. But many wind farms are being built within regions of high
seismic activity.

In Journal of Renewable and Sustainable Energy, by AIP Publishing,
researchers from Changzhou University and Beijing University of Technology present their work exploring the dynamic behaviors of wind turbines
subjected to combined wind-earthquake loading.

The group discovered that changes in the wind increase and decrease the response amplitude of the wind turbine under weak and strong earthquakes, respectively.

"The input angle of earthquakes influences the seismic response of
wind turbines, because of the asymmetry of aerodynamic damping and
blade stiffness," said Xiuli Du, a co-author from Beijing University
of Technology. "The wind and earthquake ground motion both induce the
vibration of wind turbines, especially the blades, which changes the aerodynamic load acting on the blades." Modern large-scale wind turbines
use variable speed and variable pitch control technology, which means
their dynamic behavior is affected by the controller.

"Consequently, the dynamic response of wind turbines under wind-earthquake excitation shows the coupling effect of aeroservoelasticity -- the
interactions between the inertial, elastic, and aerodynamic forces that
occur when an elastic body is subjected to a fluid flow," said Du. "Wind
and ground motion are also random vector fields, with complex time-domain
and spatial uncertainties involved when combined." Surprisingly, the researchers found the wind simultaneously exerts a dynamic loading and
damping effect on the seismic response of wind turbines. So, they caution
that considering only one of these two effects could lead to inaccurate
or even erroneous conclusions.

"Our work can guide the determination of wind-earthquake combinations
for the seismic design of wind turbines and directly help design wind
turbine structures," said Du.

Wind turbine support towers located within seismically active areas
of China do not typically include redundant supports, so if one fails,
it may result in a collapse of the turbines.

"While converting wind energy into electricity, wind turbines are in the operational state for most of their service life, which makes it important
to study the dynamic behavior of wind turbines under wind-earthquake
loading," said Du.

========================================================================== Story Source: Materials provided by American_Institute_of_Physics. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Renqiang Xi, Piguang Wang, Xiuli Du, Chengshun Xu. Dynamic
behaviors of
wind turbines under wind and earthquake excitations. Journal
of Renewable and Sustainable Energy, 2021; 13 (4): 043306 DOI:
10.1063/5.0054746 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/08/210824121028.htm

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