Environmental Engineering Reference
In-Depth Information
15.2.1 FAST (Wind Turbine Simulator)
The NREL's National Wind Technology Center (NWTC) develops advanced
computer-aided engineering (CAE) tools to support the wind industry with state-
of-the-art design and analysis capabilities. The NWTC has developed many
software tools that produce realistic models that simulate the behavior of a wind
turbine in complex environments and model the effects of turbulent inflow,
unsteady aerodynamic forces, structural dynamics, drivetrain response, control
systems, and hydrodynamic loading for offshore applications. NREL has also
developed preprocessors to build the models, post-processors to analyze the
results, and utilities to run and manage the processing tasks.
The NWTC CAE tools have become the industry standard for analysis and
development and are used by thousands of American and international wind tur-
bine designers, manufacturers, consultants, certifiers, researchers, and educators.
These tools are developed as free, publicly available, open-source, professional-
grade products as a resource for the wind industry. The open-source approach
facilitates the credibility and adaptability of the tool within the industry. The tools
are modular, well documented, and are supported by NREL through workshops
and an on-line forum (
http://wind.nrel.gov/forum/wind/viewforum.php?f=4
). They
have been verified through model-to-model comparisons, validated with test
measurements, and certified by Germanischer Lloyd. As a technical supervisory
organization, Germanischer Lloyd services include the mitigation of risks and
assurance of technical compliance for oil, gas, and industrial installations as well
as wind energy parks.
The FAST code [
8
] is a comprehensive aeroelastic simulator capable of pre-
dicting the extreme and fatigue loads of two- and three-bladed HAWTs. This sim-
ulator was chosen for validation because, in 2005, it was evaluated by Germanischer
Lloyd WindEnergie and found suitable for the calculation of onshore WT loads for
design and certification [
13
]. An interface between FAST and Simulink was also
developed with MATLAB
, enabling users to implement advanced turbine controls
in Simulink
convenient block diagram form. The FAST subroutines are linked
with a Matlab standard gateway subroutine so the FAST motion equations (in an
S-function) can be incorporated in a Simulink model. This introduces tremendous
flexibility for WT control implementation during simulation. Generator torque,
nacelle yaw, and pitch control modules can be designed in the Simulink environment
and simulated while using the complete nonlinear aeroelastic WT equations of
motion, which are available in FAST. The WT block contains the S-function block
with the FAST motion equations and blocks that integrate the degree-of-freedom
accelerations to obtain velocities and displacements. Thus, the equations of motion
are formulated in the FAST S-function and solved using one of the Simulink solvers.
FAST main features can be summarized as follows:
• Computes structural-dynamic and control-system responses as part of the aero-
hydro-servo-elastic solution.
• Uses a combined 24-DOF modal and multi-body representation.
