Wind Turbine Controller Design Based On Quasi-continuous High-order Sliding Mode

As a result of population expansion,rapid development of economy,and severe changes of global climate,worldwide countries and regions have begun to develop renewable energy power.Wind turbine becomes the fastest growing power.The characteristics of wind turbine such as nonlinear,uncertain,strong coupling and more interference present great challenges for designing controllers.Quasi-continuous high order sliding mode method is used to design controllers due to its strong robustness to external disturbances,unmodeled dynamics and parameters uncertainties,as well as the chattering phenomena can be effectively suppressed,and the relative degree limit of traditional sliding mode control method can be broken.Firstly,wind turbine models including wind speed model,wind turbine model,generator model,transmission model,and pitch actuator mode are established.On basis of these models,the simulation platforms are established then.With rated wind speed as the boundary,the control strategies of wind turbine are divided into variable speed and variable pitch.Meanwhile,the specific control objectives and strategies for variable speed and variable pitch are analyzed.Secondly,when wind speed is lower than rated wind speed,variable speed control is used based on quasi-continuous high order sliding mode control method.First,a second order torque controller is designed for two-mass transmission model.Afterwards,a third order dynamic torque controller is designed in order to further reduce chattering.Then stability proofs of these two torque controllers are deduced by theoretical analysis.At last,simulation results demonstrate that in role of the designed controllers,rotor speed can be quickly regulated through controlling generator torque,output power maximization is achieved,and system have well robustness.Finally,when wind speed is higher than rated wind speed,the strategy of designing pitch controller based on quasi-continuous high order sliding mode method is proposed in order to protect wind turbine.First,the plant model of variable pitch control system is linearized by exact feedback linearization method,and a third order pitch controller is designed for the linearized model,then its stability is proved.At last,the simulation results show that based on the designed third order pitch controller,pitch angle can be rapidly adjusted according to wind speed changes.Thereby the output power is maintained at the rated value.The robustness of system is ensured.Meanwhile,the chattering phenomena can be effectively suppressed.