Abstract
The paper proposes a method for measuring torque coefficient (CT) of a wind turbine as a function of tip speed ratio (λ). In the method, time series data representing wind and turbine speed of a wind power system are used for the measurement. The system may be operating either under constant or time varying wind of nature.. Time integrated values of the wind turbine torque of each time interval are supposed to be calculated from the turbine speed and given system parameters. Equations are derived to calculate corresponding values of λ and CT at each time portion of the input data. Experiments ware carried out to test the validity of the method both under constant and natural wind. The test result show the method will be quite applicable to practical use under constant wind speed. The results also show that, though it is promising, more improvement is necessary in measuring wind speed in the case of natural wind. Especially, a method should be established which would enable the estimation of wind speed at a turbine blade. It would utilize time series wind speed and direction data collected at some points near the turbine blade.
