Design of Variable Pitch Control Method for Floating Wind Turbine

Abstract

Because of the randomness of wind speed and the nonlinearity of the dynamic equation of variable pitch control, it is difficult to establish an accurate dynamic equation of variable pitch of floating fan. In view of this situation, this paper takes the 5 MW floating wind turbine of the NREL (National Renewable Energy Laboratory) as the research object, establishes the dynamic equation under the basic control of FAST, uses the L-M (nonlinear least square method) to identify the dynamic parameters of the system and obtains the dynamic model of the floating fan under variable pitch stability control. Compared with the output of FAST in the same case, the accuracy of the control model is verified; the FAST base pitch control adopts PI control, but the effect of FAST base control is relatively poor. This paper proposes a disturbance-adaptive pitch control method based on fractional PID feedback; the results show that compared with the FAST base pitch control, the control method is more suitable for variable pitch control of a floating wind turbine. The generating power is more stable, the overshoot of generating power is smaller and the fluctuation of wind speed is smaller. Except for surge and heave, the fluctuation of the other four degrees of the freedom of the floating wind turbine platform is reduced, making it more suitable for the variable pitch control of the floating wind turbine.

Keywords

• floating wind turbine
• variable pitch control
• fractional order PID
• stability control