Direct drive superconducting wind generators - Wind Power Generation and Wind Turbine Design - page 322

HTS Generator output

16000 16

14000 14

12000 12

10000 10

kW
kNM
RPM

8000 8

6000 6

4000 4

2000 2

0 0

0 100 200 300 400 500 600

s

Figure 14 : Generator output in simulated wind conditions.

Rotor Loss with Wind Turbulence

1000 100

800 90

600 80

400 70

Shield Loss

200 60

0 50

-200

40

-400 30

-600 20

Cold Support Loss

-800 10

-1000 0

0 100 200 300 400 500 600

time (s)

Figure 15 : Rotor loss in simulated wind conditions.

shear giving different wind velocity between a blade at the top and bottom of its
rotation and also of the effect of blades passing the tower. The resulting genera-
tor speed (top trace), output kW (middle trace) and torque (bottom trace) is
shown in Fig. 14. The resulting eddy current losses in the rotor cold parts and the
warm electromagnetic shield surrounding the rotor are shown in Fig. 15.
Although there is high instantaneous loss at the instant of sudden changes, the
average loss is low, requiring negligible additional cooling power. The fl uctuations
in fl ux density in the HTS were also found to be small. AC components of current
and magnetic fl ux density are known to induce losses in the HTS wire (known as
AC loss), which was not included in the analysis. AC loss in superconductors is