Worksheet

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Comp2252 Modelling and Simulation. Worksheet 11.
Purpose
(a) To understand the structure of a wind turbine, (b) To appreciate the concept of “control” of a system, (c)
To validate a mathematical model of a wind turbine (limited to Region 2), (d) To investigate the response of
a wind turbine model to stepwise changes in wind speed, (e) To investigate the response of a wind turbine
model to typical wind speed variations
Background
This workshop concerns a study of a particular wind turbine, the “CART3” turbine at the National
Renewable Energy Laboratory, Colorado, US. This is a 3-bladed turbine rated at 600 kilowatts which is used
for research and development purposes. The data used in this workshop has been obtained from the research
literature, supplemented by personal communication with the Principal Engineer (Turbine Engineering) at
GL Garrard Hassan in Bristol UK. So in this workshop, you are invited to construct a simulation of a real
wind turbine.
Note that all declared variables and their relations to the theory are presented in a table in Chapter 10.
Associated Reading
Chapter 10 Wind Turbine Control
Activities
0
Installation. Install the code template CBP_WindTurb_Torque.uc into the CBP55 classes folder
and the level CBP55_Lab_WindTorq.udk into the CBP55_Content folder.
1
Writing Code and Verification. Using the lecture notes and the associated reading, complete the
code to compute the dynamics of the wind turbine in Region 2. Using the supplied level, check that
your wind turbine rotates at a reasonable rate and responds to console changes in the wind speed.
2
Validation. The model can be validated by investigating how the generated power depends on the
wind velocity and comparing this with theory. You should run your simulation for wind velocities
from say 4 to 11 m/s and record the generated power, as displayed on the HUD. To speed up your
simulation, you may want to set J = 1000 using the console. This makes the simulation react faster
to any changes you make. Note down the value of Cp from the HUD.
Import your data into Excel, and make a scatterplot. Then fit a trend line of the type “power”, and
display the equation on your plot. You should get something like 𝑦 = 𝐴𝑥 3 where A is some number
like 0.3. If your result is not close to this, then something is wrong with your code.
Remember the theoretical expression for power as a function of wind speed is
1
𝑃 = 2 𝜌𝜋𝑅 2 𝐶𝑝 𝑣 3
1
So your number A on the plot should be the same as 2 𝜌𝜋𝑅 2 𝐶𝑝 . Calculate this for the values
provided and your observation of Cp. Calculate the percentage error difference and this should
validate the model at a particular level.
3.
Planning your Investigation. There are a couple of approaches to investigating a “control system”
as presented here:
(a) Investigating how the system responds to a “step” change in input. For example, how do the
output power and rotational velocity change when the wind speed is raised from 8 to 10 m/s? You
should also look at how Cp and tsr change?
(b) Investigating how the system responds to typical “real world” inputs, here that means realistic
wind speeds. The code supplied contains a model of varying windspeeds which can be activated by
setting bApplyRandomWindSpeeds=true in the Editor, which will produce some realistic gusts of
wind. (Of course you should not change the wind speed from the console when this is switched on).
Of course you may choose to do something totally different, such as investigating how the rotor
radius R affects the power generated at a certain wind speed.
4.
Decide which variables you need to add to the HUD and also which to log in the data file to support
your chosen investigations.
Conducting your Investigation. Before you begin, make sure the turbine properties in the Editor
agree with the default properties for the CART3 turbine. Do not reduce J to speed up the simulation;
you need to simulate the actual CART3 turbine.
Now you should be confident in recording data, importing it into Excel and making a good shot at
interpreting the data. So no hints are presented here 
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