Research On Power And Load Optimization Control Of Floating Offshore Wind Turbines

While offshore wind power has the characteristics of adequate wind energy and no waste of soil resources compared to onshore wind power,it has been highly popular.Yet with the gradual saturation of resources in inshore areas,making offshore wind power to the deep sea has become inevitable.Floating platforms offer the possibility for offshore wind power in deep ocean.The external loads and system modeling for floating offshore wind turbine systems,by contrast,are far more challenging than for onshore and offshore wind turbines.More movement of the floating platform under the influence of external load.Thus,under the complex external environment and system model uncertainty,it is necessary to design a control strategy for floating wind turbines to achieve the purpose of suppressing platform motion,stabilizing output power and reducing fatigue load on the turbine.In this paper,we design variable pitch control methods such as sliding mode and advanced PID for 5 MW barge-type floating wind turbine.FAST and MATLAB/Simulink form a joint simulation platform.The proposed control scheme is compared with the conventional PI control for verification.Analysis from three aspects of power,platform dynamic response and dynamic load.Details of the work are as follows:(1)For strongly nonlinear,strongly coupled floating wind power systems,the uncertain affine nonlinear model of floating wind turbine is constructed.The rotor reference speed depending on the platform speed is used to design the sliding mode surface.The super-twisting algorithm is used as a second-order sliding mode collective pitch control law to reduce chattering and solve the wind turbine performance problem.(2)If the upper bound of the system uncertainty term is unknown,large pitch controller switching gain will cause sliding mode control chatter.Therefore,the application of adaptive sliding mode control to wind turbine systems.An adaptive highorder sliding mode control strategy based on Barrier function is proposed for collective pitch control of floating wind turbines.Design adaptive law for control parameters to solve the unknown upper bound of system uncertainty and realize adaptive adjustment according to random disturbance of waves and wind speed.(3)The coupling of the collective pitch motion with the platform motion leads to a negative damping effect,which intensifies the platform motion.Therefore,individual pitch control strategy is proposed to deal with the blade torque problem and improve the platform motion.Design a control strategy combining fuzzy PID collective pitch control and radial basis function neural network(RBFNN)adjusted PID individual pitch control.To solve the problems of unstable dynamic performance of the unit under traditional PID control,difficult adjustment of controller parameters and poor adaptability.Achieve the purpose of reducing the platform motion and suppressing the dynamic load and power fluctuation of the wind turbine.