Research On LPV Fault-tolerant Control Method For Wind Energy Conversion System

With the rapid development of society,non-renewable energy consumption is faster and faster.For this to find renewable energy supply has become a hot topic for the majority of researchers.Wind energy because of its sustainability,environmental protection and high efficiency was recognized by people.However,the wind turbine is often located in remote mountains,tidal seaside and other harsh environments,At high wind speeds,the wind turbine pitch angle system working to regulate wind energy capture,so the possibility of a pitch angle component failure is large,that making the wind turbine running is not stable enough,its service life is also greatly reduced.For the fault problem of the wind turbine pitch angle system,the LPV(linear variable parameter)fault-tolerant control method will be referred to the wind turbine system.Based on the construction of double convex polyhedron,Fault tolerance control is using for fault problems in pitch angle systems.This paper has made the following research:In order to solve the deviation in the process of linearized modeling,this method which is based on the double-layer convex polyhedron structure is proposed to design the linear varying parameter controller.Firstly,the traditional model with scheduling variables is converted into the model with double-layer convex polyhedron structure.Then Combined with the gain scheduling technique and the linear matrix inequality method,the vertex controllers are constructed at the outer sphere convex polyhedron.Finally,the inner sphere convex polyhedron controllers are figure out according to the vertices controllers.The method is aimed to weakened the linear deviation,enhance the control effect of controller.The simulation results show that the wind turbine operate with more stable output power and more lower mechanical stress compare to the performance of traditional controller.In view of the time-varying bias faults of wind turbine pitch Angle system,The observer of adaptive convex polyhedron and improved fault estimation algorithm are proposed on the basis of the traditional fault observer.The LPV fault tolerant controller of double convex polyhedron is designed on the premise of obtaining the estimated fault signal,combining scheduling variables of real-time measurable and linear matrix inequality technique.This method not only eliminates the linearization error of the traditional model of single layer structure,but also improve the linearization degree of the system,and guarantee the inhibiting effect of the controller to faults.Meanwhile,the fault diagnosis observer and output feedback fault tolerant controller are designed separately and their performances are considered simultaneously to simplify design procedures.Finally,simulation results are presented to show the effectiveness of the proposed method.To address failures of wind turbine pitch-angle sensors,traditional wind turbine linear parameter varying(LPV)model is transformed into a double-layer convex polyhedron LPV model.In order to meet the demand,the original model is expand from 6 to 10 order.On the basis of this model,when a plurality of the sensor undergoes failure and details of the failure are inconvenient to obtain,each sub-controller is designed using distributed method and Zero processing method.The final controller is obtained using all of the sub-controllers by a convex combination.The design method corrects errors of the linear model,improves the linear degree of the system,and solves the problem of multiple pitch angle fault to ensure stable operation of the wind turbine.