A control structure ?feed forward of estimated wind speed? is described,as it were: ?the wind turbine rotor will be used as a wind meter?.
The control structure is based on ?estimation? of wind speed as well
as a non-linear compensation of a wind speed dependent pitch speed setpoint,
which is optimised to maintain (stationary) rated electric power. It
is required to know the rotor properties with moderate accuracy.
In time domain simulations, inclusion of a feed forward of estimated
wind speed control action has shown to be a powerful extension to current
ECN wind turbine control structures:
- reduction of rotor speed variations: 0.2 rpm
decreased standard deviation;
- improved turbine behaviour to large wind gusts;
- increase of energy yield of
0.9%;
For reasons of simplicity and robustness, a tabular implementation approach
is preferred above polynomial implementation. The resulting brief algorithm
uses small sized tables, requires low hardware requirements and needs
a minimum of easy interpretable parameters for design and tuning.
Both stability, robustness and parametric uncertainties were observed.
The addition control loop has a slightly positive effect on overall
stability and robustness. Appeared offsets in the estimated wind speed
value due to parameter uncertainties do not have impact on the effectuation
of the wind speed feed forward loop.