Vibration Control Of Wind Turbine Blades Based On Robust Control

With the large-scale trend of modern wind turbines,the expand in blade leads to a large radius of the rotor,which increases the flexibility of the blade.Under the action of the wind load,vibration will be generated.This not only affects the safe operation and service life of the wind turbine but also causes the generator torque to fluctuate,which affects the safety and stability of the power grid.In this context,it is of great theoretical and practical significance to establish the overall dynamics model of wind turbines,and analyze its dynamic characteristics.Based on this,it is significant to select suitable damping devices,and design controllers to reduce the vibration of wind turbines.Wind turbines are complex multi-body system with the coupling of rigid and flexible.The blades and towers are flexible,while the nacelle is a rigid body.Subject to the aerodynamic load,it will generate flapwise,edgewise and torsion in the rotating blades;meantime the tower is vibration in for-aft,side-to-side and torsional direction.The coupling is existing of each subsystem,such as the coupling of the blade flapwise vibration with the tower for-aft vibration,and the coupling of the blade edgewise to the lateral vibration of the tower.Because the coupling between the mechanical component and the generator via drive train,the generator dynamics also affect the blade vibration.Due to the unmodeled dynamics of the system,parameters uncertain and structural uncertainties,the real engineering system will be affected by the uncertainty.A model error may lead to the degradation of system performance.It is crucial to consider the influence of uncertainty on the system in system modeling and controller design.Therefore,it is necessary to consider a variety of system uncertainties including parameter uncertainty and dynamic uncertainty in the procedure of robust control design.This paper focuses on the key technical issues of blade vibration control,including dynamics modeling of blade vibration and robust control issues.The main research contents are as follows:1.The control-oriented coupled multi-body dynamics model of wind turbine is established,including the coupling of mechanical model and electrical model.A full coupling model of the blade-tower-drivetrain-grid is obtained,which is used to analyze the influence of grid dynamics on the mechanical vibration.Through modeling and simulation analysis,it is concluded that the fluctuate of generator torque will aggravate the in-plane vibration of the blade.2.Structural control of the blade via robust control is studied.Because the wind load has stochastic characteristics,we consider the robust control of stochastic uncertainty system.For the stochastic uncertainty system,the minimax robust linear quadratic Gaussian(LQG)control is designed according to the equivalent of the stochastic integral quadratic constraint(IQC)and the relative entropy constraint to guarantee the closed-loop system absolutely stability.For the problem of blade vibration control,a variety of system uncertainties,including parameter uncertainty and dynamic uncertainty,are considered.The simulation results show that the blade vibration can be effectively suppressed.3 The decentralized control of stochastic uncertain system is investigated.In view of the dynamic coupling of the blade and the tower,the coupled model should be considered in the control design.The large-scale trend of modern wind turbines leads to the control strategy requires a large number of sensors and communication networks.For the large structure,decentralized control is a more practical approach.Robust decentralized minimax LQG control is proposed based on minimax LQG control theory.The simulation results show that the decentralized control can achieve similar control effects as centralized control.4 For the deterministic system,the robust control of the uncertain system satisfying the integral quadratic constraint is studied.The control design is proposed via static output feedback control approach,which guarantees the H? performance of the closed-loop system under the structural information constraint.5.For the structure control of the blade using TMD,the dynamic model of the system under the variable speed of the rotor is established.In this paper,the structural model including dynamic of TMD is developed to design a robust decentralized H? control that satisfies the integral quadratic constraint.The simulation results show that the decentralized control based on the decentralized multiple TMDs in the blade can effectively suppress the blade vibration.