  The cost of wind energy can be reduced by controlling the power reference of
a turbine to increase energy capture, while maintaining load and generator
speed constraints. We apply standard torque and pitch controllers to the direct
inputs of the turbine and use their set points to change the power output and
reduce generator speed and blade load transients. A power reference controller
increases the power output when conditions are safe and decreases it when
problematic transient events are expected. Transient generator speeds and blade
loads are estimated using a gust measure derived from a wind speed estimate. A
hybrid controller decreases the power rating from a maximum allowable power.
Compared to a baseline controller, with a constant power reference, the
proposed controller results in generator speeds and blade loads that do not
exceed the original limits, increases tower fore-aft damage equivalent loads by
1%, and increases the annual energy production by 5%.
