Page 254 - Renewable Energy Devices and System with Simulations in MATLAB and ANSYS

Electric Generators and their Control for Large Wind Turbines 241

Note: The multiobjective optimal design of PMSG or DCE-SG could be attempted by multiob-
jective evolutionary, differential evolutionary, and optimization methodology where FEM machine
modeling is exclusively used but only in 10–12 points per electrical period to reduce the computa-
tional time. The computational time is higher (at least 50 h on a strong multi-desk computer crew),
but much more information on the design and its robustness may be collected [18, 19].
More data on the optimized 7.6 MW, 11 rpm DCE-SG design are summarized in Table 9.6 and
in Figures 9.27 through 9.30.

V characteristics
1.2

1

Load current (pu) 0.8

0.6

0.4 P =0
P =0.25
P =0.5
0.2 P =0.75
P =1
lex limit
0 ls limit
0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2
Excitation current (pu)

FIGURE 9.28 V curves DCE-SG.

P/Q diagram
12
Stator-rated current
Rated power
10 8 Excit. limit
Ideal stab.
Active power P (MW) 6 4 i =0
Practic. stab.
e
i =0.1
e

2

0
–12 –10 –8 –6 –4 –2 0 2 4 6 8
Reactive power Q (MVAr)

FIGURE 9.29 Active–reactive power capabilities of DCE-SG.