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N° 43 -  October 2003 - CEDRAT - CEDRAT TECHNOLOGIES - MAGSOFT Corp.

SOFTWARE

>>

E

lectrical distributed 
generation produced with 
renewable energy (wind, 

solar, biomass, fuel-cells,etc.) 
takes more and more importance 
in the global electrical production.
The power which can be produced 
with a windmill (2.5 MVA), as well 
as the committed sums (1000€ for 
1 KW installed) imply to carry out 
simulations in order to make the 
good technological choices and 
analyze the network connection 
consequences as well as study 
economic profi tability.
PSCAD integrates all tools 
necessary to simulate a windmill 
and its connection to the network. 
Such a study has been performed 
in CEDRAT and is presented in the 
technical paper «Wind Turbine 
and Grid Connection Modelling 
with PSCAD».

The tools

These 3 components (fi g.1), 
designed according to IEEE 
models, are available in the PSCAD 
Master library and make it possible 
to simulate all the parameters 
involved in a wind mill study : 
● 

Wind sources: possibility 

to simulate different wind 
distributions (gusts, random,etc.),
●  Pitch regulation : the «passive 
pitch control» and the «dynamic 
pitch control» which play on 
incidence angle of the blades 
(Beta),
●  The choice of the number of 
blades from which depends the 
power coeffi cient characteristics of 
the turbine (Cp),
●  The blade length (R) and the 
air density (

ρ) which make it 

possible to calculate the output 
power of the turbine (P = ½ Cp 

ρ 

π R

2

 Vvent

3

) and the corresponding 

torque,
●  The step-up ratio and the ef-
fi ciency of the gear box located 

between the turbine 
hub and the genera-
tor hub.

The model

Many recent wind 
mills use synchro-
nous brushless ma-
chines like annular 
or discoidal multipo-
lar generators with 
permanent magnets. 
They are weaker 
than traditional ge-
nerators at identical 
torque and speed 
(the mass reduction 
according to techno-
logy can reach from 
20 to 40%). Another 
advantage is that 
these machines can 
have a great num-
ber of poles (200) 
and thus rotate at 
low speed without 
mechanical multi-
plier. A conversion 
stage AC/DC/AC is 
necessary in order to 
be connected to the 
network at the con-
venient frequency. 
The PSCAD models 
make it possible to 
simulate this type of 
generator with all the 
required power elec-
tronic devices. 
The complete simu-
lation scheme is pro-
posed on fi g. 2.

Simulations

The simulations performed with 
PSCAD allowed us to study 
the dimensionning of the wind 
turbine and the generator, the 
DC bus voltage regulation and 
the connection to the distribution 
network.
In fi gure 3, you can observe the 
difference in the power produced 
by a wind generator in static pitch 
control (blue curve) or dynamic 
pitch control (green curve) with a 
variable wind speed.

Faults analysis have been made 
with PSCAD allowing to know the 
infl uence of the wind mill on the 
network in such confi gurations 
and to defi ne the protections to 
choose. 

Finally, an entire wind farm 
(300 MVA) has been modelled in 
PSCAD. Voltage and frequency 
stability investigations at the 
connection point have been 
performed, de to the high power 
level of the windfarm compared 
with the connected grid.

Conclusion

PSCAD tools and capabilities 
allowed to see a large part of the 
technical aspects of a wind-mill 
dimensionning and its connection 
to the network. You will fi nd  all 
the details of this study in the 
technical paper: «Wind Turbine 
and Grid Connection Modelling 
with PSCAD», available on 
software@cedrat.com.

Wind Turbine and Grid Connection Modelling with 
PSCAD. 

Eric Flammier - EDF; Augstin M'Panda - ESIEE; Fabrice Foucher - CEDRAT.

Figure1: PSCAD model 

deicated at wind turbine.

Figure 2: PSCAD model.

Figure 3: Power received on the network 

in static and pitch control.