Research On Fault Diagnosis And Fault Tolerant Control Strategy Of Wind Turbine System

Wind energy is one of the most mature renewable energy resources in the world with large-scale development and application conditions and commercial development prospects.Vigorously developing wind power generation technology will promote the reform of energy structure.Wind turbine has complex structures and is susceptible to harsh operating environments.Thus,wind turbine is prone to failure or even shutdown,which brings huge economic losses.In the actual wind turbine system,fault diagnosis technology and fault-tolerant control can ensure the efficiency of power conversion and reduce the accident rate of equipment and maintenance costs.Thus,fault diagnosis and fault-tolerant control are indispensable solutions to ensure the reliable operation of modern wind turbines,which have good theoretical research and engineering application value.This paper deeply analyzes the research status of fault diagnosis and fault-tolerant control of wind turbine at home and abroad,and introduces the reference model of wind turbine system in detail,including wind speed model,pitch system,aerodynamic system,driven system and other independent and interrelated subsystems,which lays a theoretical foundation for the follow-up research.Considering that wind turbines are susceptible to external uncertainties,noise and unknown input,fault models for single and multiple sensor faults in the driven system is determined for the problem of multi-sensor faults in the driven system of wind turbines.Based on the theory of unknown input observers,the observers with single-sensor failure and the observers with multiple-sensor failure are designed respectively,which weakens the influence of unknown external factors on the residual error of the fault.By comparing the residual results generated by the unknown input observers,the single or multiple sensor fault diagnosis of the wind turbine drive system is realized.Considering the problem that the unknown input cannot be completely decoupled in the actual wind turbine system,the unknown input is decomposed into decoupable part and the non-decoupable part by using the equality condition of the unknown input observer,and the decoupable part is estimated from the estimation error.Then,H_-/H_?unknown input observer is designed by introducing theH_-/H_?performance indicators,which are used to enhance the sensitivity of residual to fault signal and the robustness to uncoupled disturbance.According to the principle of mathematical statistics,the appropriate residual threshld is set for the effective diagnosis of sensor additive fault and multiplicative fault in the driven system of wind turbine,which provides fault diagnosis results for fault-tolerant control.For different working points of wind turbine without fault,the corresponding fault-tolerant controllers are designed based on model predictive control.The problem of transient response caused by switching between multiple controllers is solved by introducing the strategy of switching control.After obtaining the fault diagnosis information of the unknown input observer,the model predictive fault-tolerant controllers compensate the sensor output to ensure that it is consistent with the fault-free output,to achieve the fault-tolerant control of driven system in time and effectively.Simulation analysis of the proposed fault diagnosis and fault tolerance control strategy is performed based on the Simulink platform of MATLAB.The simulation results show that the proposed control strategy can carry out fault diagnosis and fault-tolerant control in time in case of system failure,and the output power of the system can be consistent with that of the fault-free system,which has important practical application significance.