Direct drive superconducting wind generators - Wind Power Generation and Wind Turbine Design - page 327

Figure 18: Large cryostat with a prototype HTS coil in a magnetic circuit at
Converteam Ltd., Rugby.
simulated magnetic circuit in a small cryostat. These coils were successfully tested
up to an operating current of 230 A, compared to the 140 A operating current in the
model generator.
Following on from these tests Converteam opened a cryogenics laboratory in
their Rugby facility to support all HTS projects, with a large cryostat (8 m 3 vacuum
space) capable of accommodating the coils for the full size wind generator, shown
in Fig. 18 during the setting up of a test.
6.8 The full scale detailed design
Following discussions with a wind turbine manufacturer, the rating of the full size
generator was changed to 10 MW at 11.5 rpm, to suit their planned turbine devel-
opment. The 10 MW design was scaled from the 8 MW concept design, resulting
in a slight increase in diameter to 5.4 m, an increase in length to 2.6 m, and a mass
of less than 140 tonnes.
The design is based on the expected performance of the best HTS wire in 2010,
the earliest time when wire will need to be ordered for the full size prototype gen-
erator. This is expected to require an operating temperature of 40 K. The helium gas
cooling system used in the design permits the operating temperature to be easily
changed when future improvements in HTS wire performance permit.
7 T he way forward
The next logical step will be the manufacture and test of a full size prototype, fol-
lowed by its demonstration on the 10 MW turbine. In parallel with this the supply
chain development and engineering of the manufacturing process for production
manufacturing will take place before the start of commercial volume production,
which could begin by 2015.