Research On Independent Pitch Control Of Offshore Floating Wind Turbine Based On Adaptive Fault-tolerant Control

Wind power generation is considered as one of the most promising renewable energy sources in modern power system.As the offshore wind energy resources are rich,the visual impact and noise impact are less,so it has become the current research hotspot of scholars.With the commercial scale of offshore wind farms,the physical size of wind turbines increases gradually,so it is necessary to reconsider the effect of wind turbine load reduction.And the floating offshore wind turbine has no fixed base,its floating platform has six degrees of freedom,and its motion characteristics are more complex.In this complex operating environment,system parameters are difficult to determine.It is also difficult to calculate the coupling effect of wind and wave on the structure.Advanced control methods are urgently needed to maintain output power stability and reduce unit load.The independent pitch control method can effectively reduce the load of the unit,solve the problem of uneven load distribution,and maintain the stability of output power.The small fault of the control system of wind turbine will have an unexpected impact on the system performance.So the designed controller has a certain fault-tolerant ability,which is of great theoretical significance and application value for the variable pitch system of the floating wind turbine.The following is the main research work of this paper:(1)The structure,aerodynamics,hydrodynamics and mooring system of offshore floating wind turbine are studied.Aiming at the problem of load reduction of spar wind turbine,this paper analyzes the main load of floating wind turbine,and expounds the importance of load control to ensure the reliable and stable operation of the unit.Considering the six degrees of freedom of the floating platform,including surge,sway,heave,roll,pitch and yaw,and the first-order motion mode of the tower,the high fidelity modeling of the system is realized.(2)Aiming at the non-linearity of variable pitch system and the uncertainty of parameters of floating wind turbine,the dynamic load reduction problem of axial unbalanced aerodynamic load of blade is integrated.Firstly,the force of blade is analyzed.Then,a more accurate nonlinear dynamic system model is established.(3)In this paper,the dynamic load reduction problem of blade under axial unbalanced aerodynamic load is studied,and the system is a multi input and multi output nonlinear dynamic system.Therefore,the neural adaptive tracking control method is designed.This method can realize reliable independent pitch tracking control under normal conditions.Considering the influence of actuator fault and external disturbance,the system fault model is established.The neural adaptive fault-tolerant tracking control method is designed,so that the actual output pitch angle can still effectively track the desired pitch angle in the case of actuator failure.Finally,uniform bounded stable tracking control is realized.(4)Based on the joint simulation platform of FAST and MATLAB,a 5 MW spar type floating wind turbine is simulated and analyzed.Finally,it is verified that the proposed control method has good control effect and fault tolerance,and can stabilize power and reduce load.