Development of Gearless Variable Speed Wind Turbine |
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Wind Turbine Generator Systems (WTGSs) are coming rapidly into wide use in electricity
generation because they use wind renewable energy and do not emit pollutants.
Improvements up to now have mainly been in cost saving and reliability. Changes
in power due to changes in wind speed adversely affect such electrical grid-line
properties as frequency and voltage, which is why variable-speeds wind turbines
that reduce adverse effects have attracted attention.
MHI has developed the MWT-300S gearless variable-speed wind turbine with a permanent
magnet synchronous generator in collaboration with Mitsubishi Electric Co. The
first unit was installed at Tappi Wind Park, operated by Tohoku Electric Power
Co. Inc. (TEPCI) in Aomori Prefecture, for demonstrative operation to study power
performance, durability and reliability in July 2000 under a joint operational
project between TEPCI and MHI.
 The new wind turbine features
a Permanent Magnet Generator (PMGWTGS) for (1) reduced power fluctuation and inrush
current, (2) reduced noise, and (3) improved maintenance. The first two features
have been demonstrated since July in test operation, with more detailed operating
characteristics to be measured in future.
The table on the right shows
the main specifications of the PMGWTGS, while the photo shows an overall view
of the unit. The PMG consists of stator windings and multi-pole permanent magnet
rotor. The magnetic substance used in the rotor is neodymium, a kind of rare-earth
magnet.
Main Specifications
| Step-up gear |
|
No-gear (direct-drive) |
| Generator |
|
Permanent magnet synchronous generator |
| Rated power |
|
300 kW |
| Rotor diameter |
|
30 m |
| Rotor rotational speed |
|
16-49 rpm
Full-range variable speed |
| Power regulation |
|
Blade pitch control |
| Cut-in wind speed |
|
2.5 m/s |
| Rated wind speed |
|
14.0 m/s |
| Cut-out wind speed |
|
25.0 m/s |
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