This is the final report of a Danish research project “Grid fault
and design-basis for wind turbines”. The objective of this project
has been to assess and analyze the consequences of the new grid
connection requirements for the fatigue and ultimate structural
loads of wind turbines.
The fulfillment of the grid connection requirements poses
challenges for the design of both the electrical system and the
mechanical structure of wind turbines. The development of wind
turbine models and novel control strategies to fulfill the TSO’s
requirements are of vital importance in this design. Dynamic
models and different fault ride-through control strategies have been
developed and assessed in this project for three different wind
turbine concepts (active stall wind turbine, variable speed doublyfed
induction generator wind turbine, variable speed multipole
permanent magnet wind turbine).
A computer approach for the quantification of the wind turbines
structural loads caused by the fault ride-through grid requirement,
has been proposed and exemplified for the case of an active stall
wind turbine. This approach relies on the combination of
knowledge from complimentary simulation tools, which have
expertise in different specialized design areas for wind turbines.
In order to quantify the impact of the grid faults and grid
requirements fulfillment on wind turbines structural loads and thus
on their lifetime, a rainflow and a statistical analysis for fatigue and
ultimate structural loads, respectively, have been performed and
compared for two cases, i.e. one when the turbine is immediately
disconnected from the grid when a grid fault occurs and one when
the turbine is equipped with a fault ride-through controller and
therefore it is able to remain connected to the grid during the grid
Different storm control strategies, that enable variable speed
wind turbines to produce power at wind speeds higher than 25m/s
and up to 50m/s without substantially increasing the structural
loads, have also been proposed and investigated during the project.
Statistics in terms of mean value and standard deviation have been
analysed and rainflow calculations have been performed to estimate
the impact over the lifetime of a variable speed wind turbine.
|Series||Denmark. Forskningscenter Risoe. Risoe-R|
- Wind power control and integration
- Wind energy