Experimental study on aerodynamic control of horizontal axis wind turbine using inflow observation

For the further introduction of wind power generation, it is necessary to solve the problems with output power fluctuation and early failure of wind turbine components. These problems are caused by the fluctuation of wind which is the energy source of wind power generation. In this paper, to solve these problems, the wind turbine controls that suppress the fluctuations of wind turbine power and the rotor thrust by using the inflow wind observed by LiDAR and ultrasonic anemometer are developed. The feedforward control for the pitch system is demonstrated with a 100 kW test wind turbine. For the feedforward control, the blade pitch angle is set to suppress the fluctuation of power or the rotor thrust according to the inflow wind velocity. The target pitch angle is determined by referring to the inflow wind velocity, wind turbine conditions, and the database constructed by using numerical analysis. The time series of the pitch angle command is fitted to the timing of inflow wind arrival to the rotor plane. A LiDAR installed downstream of the wind turbine rotor on the ground and an ultrasonic anemometer on a reference mast installed upstream of the rotor are used as observation devices for the inflow wind velocity. The suppression effect for the power or the rotor thrust fluctuation by feedforward control with pitch control was verified for either LiDAR or ultrasonic anemometer. Then, the demonstration results are compared with the LiDAR's control system and the ultrasonic anemometer's control system and evaluated. The feedforward controls assisted by LiDAR or ultrasonic anemometer are able to suppress the power and the rotor thrust exceeding the target value. Ultrasonic-anemometer-assisted feedforward control is able to suppress the fluctuation of power and load with high accuracy because the ultrasonic anemometer can accurately observe the inflow wind velocity.